Search

The increasing discoveries of new species of the family Lucinidae in the last two decades indicated a surprising diversity of chemosynthetic lucinids in the deep sea, especially in the Indo-West Pacific. However, only a few records have been reported from the South China Sea. A new lucinid species Elliptiolucina subovalissp. nov. is here reported from a deep-sea cold seep site of the South China Sea. The new species is distinct from its congeners by possessing a strong anterior lateral tooth on the right valve and anterior tapering, subrectangular-oval shells. Sequences of three genes (18S rRNA, 28S rRNA, and CytB) were used to analyze its relationships with other species in the subfamily Myrteinae and confirm its taxonomic placement. The result supports the monophyly of Myrteinae but also demonstrates the polyphyly of Elliptiolucina. The new species has a close relationship with E. williamsae and Rostrilucina garuda, but is not closely related to congener E. ingens. By comparing morphological characters, we suggest that E. ingens should not belong to the genus Elliptiolucina. The basal two of three deep-sea clades recognized in Myrteinae may indicate the deep-sea origin of this subfamily. Our results add to the known diversity of deep-sea lucinids and molecular information for poorly studied Myrteinae and highlight the necessity of further investigation on deep-sea lucinids of the South China Sea.

Parathyasira coani sp. nov. urn:lsid:zoobank.org:act: B88594C5-63A1-4111-909B-D2359BB41965 Figs 2–6, Table 1 Parathyasira sp. 2 – Kamenev 2015: 191. Parathyasira sp. – Kamenev 2019: 6. Diagnosis Shell medium in size (to 7.5 mm in length), obliquely-rhomboidal, slightly drawn out anteriorly. Sculpture of closely spaced commarginal riblets and weak undulations. Second posterior fold weak. Posterior sulcus weak. Escutcheon long, deep. Lunule long, flat, weakly defined. Ligament well visible externally, long. Prodissoconch large (to 250 µm) with 5 lamellated folds. Lateral body pouches large, extensively lobed. Foot distally bulbous; bulbous portion not divided into two distinct parts; heel absent. Etymology The species epithet honors Dr Eugene V. Coan, a well-known researcher of eastern Pacific bivalves who made an enormous contribution to the study of the bivalve fauna of the Pacific Ocean. Material examined Holotype PACIFIC OCEAN • abyssal plain adjacent to the southern part of the Kuril-Kamchatka Trench; 39°43.80′ N, 147°10.16′ E –39°42.49′ N, 147°09.37′ E; depth 5224– 5215 m; 1 Sep. 2012; A. Brandt leg.; epibenthic sledge, RV Sonne, cruise no. 223, stn. 12-4; MIMB 43813. Paratypes PACIFIC OCEAN • 2 specs; same locality as for holotype; 40°13.26′ N, 148°06.24′ E –40°12.37′ N, 148°05.43′ E; depth 5348–5350 m; epibenthic sledge; 30 Aug. 2012; A. Brandt leg.; RV Sonne, cruise no. 223, stn. 11-9; SMF 367801 • 1 spec.; same collection data as for preceding; MIMB 43814 • 1 spec.; same locality as for holotype; 40°13.10′ N, 148°06.45′ E –40°12.10′ N, 148°06.45′ E; depth 5351– 5348 m; 31 Aug. 2012; A. Brandt leg.; epibenthic sledge, RV Sonne, cruise no. 223, stn. 11-12; MIMB 43815. Other material RUSSIA – oceanic slope of the Kamchatka Peninsula • 2 specs; 53°05.4′ N, 161°55.2′ E –53°07′ N, 161°56.1′ E; depth 4890–4984 m; 10 Aug. 1990; L.I. Moskalev and S.V. Galkin leg.; Sigsbee trawl; RV Akademik Mstislav Keldysh, cruise no. 22, stn. 2323; IORAS OBF collection Cat. BIV00044. PACIFIC OCEAN – abyssal plain adjacent to the Kuril-Kamchatka Trench • 7 specs; 41°16′ N, 147°27.7′ E; depth 5210 m; 20 Aug. 1954; P.L. Bezrukov leg.; Okean grab (0.25 m 2); RV Vityaz, cruise no. 19, stn. 3102; IORAS OBF collection Cat. BIV00043 • 6 specs; same locality as for preceding; 40°13.26′ N, 148°06.24′E –40°12.37′ N, 148°05.43′ E; depth 5348–5350 m; 30 Aug. 2012; A. Brandt leg.; epibenthic sledge, RV Sonne, cruise no. 223, stn. 11-9; MIMB 43816 • 2 specs; same locality as for preceding; 40°13.33′ N, 148°06.48′ E –40°12.53′ N, 148°05.76′ E; depth 5348– 5347 m; 30 Aug. 2012; K.V. Minin leg.;Agassiz trawl, RV Sonne, cruise no. 223, stn. 11-10; MIMB 43817 • 5 specs; same locality as for preceding; 40°13.10′ N, 148°06.45′ E –40°12.10′ N, 148°05.53′ E; depth 5351– 5348 m; epibenthic sledge, RV Sonne, cruise no. 223, stn. 11-12; 31 Aug. 2012; A. Brandt leg.; MIMB 43818 • 13 specs; same locality as for preceding; 39°43.80′ N, 147°10.16′ E –39°42.49′ N, 147°09.37′ E; depth 5224– 5215 m; A. Brandt leg.; epibenthic sledge, RV Sonne, cruise no. 223, stn. 12-4; 1 Sep. 2012; MIMB 43819 • 1 spec.; same locality as for preceding; 39°43.47′ N, 147°10.11′ E –39°42.54′ N, 147°09.51′ E; depth 5229– 5217 m; 1 Sep. 2012; K.V. Minin leg.; Agassiz trawl, RV Sonne, cruise no. 223, stn. 12-5; MIMB 43820. – Kuril-Kamchatka Trench • 1 spec.; 45°56.587′ N, 152°54.251′ E –45°56.570′ N, 152°54.499′ E; depth 6204– 6202 m; 26 Aug. 2016; K.V. Minin leg.; Agassiz trawl, RV Sonne, cruise no. 250, stn. 29; MIMB 43821 • 1 spec.; same locality as for preceding; 45°56.821′ N, 152°51.185′ E –45°56.834′ N, 152°50.943′ E; depth 6168– 6164 m; 27 Aug. 2016; A. Brandt leg.; epibenthic sledge, RV Sonne, cruise no. 250, stn. 30; MIMB 43822. Description SHELL. Medium in size (to 7.5 mm in length and 7.3 mm in height). Obliquely-rhomboidal, equivalve, subequilateral, white, thick, inflated (W/L= 0.56 ±0.06), almost as long as high (H/L=1.01 ± 0.03), slightly drawn out anteriorly; patches of silty and ferruginous deposit adhering to anterodorsal and posterodorsal shell margins (Fig.2, Table1). Periostracum thin, colorless, adherent.Dissoconch sculptured with closely spaced, thin, smoothed, commarginal riblets and weak, wide, irregular undulations. Microsculpture of small, densely spaced, wrinkles (Fig. 3C–D). Beaks small, raised, pointed, prosogyrate, anterior to midline (A/L= 0.40 ±0.02) (Table 1). Anterodorsal shell margin long, slightly concave, sometimes straight, gently sloping from beaks, forming a rounded angle at transition to anterior margin. Anterior margin strongly curved, smoothly transitioning to ventral margin. Ventral margin strongly curved, sometimes slightly angulate. Posterodorsal margin long, convex, steeply sloping from beaks, forming distinct angle at transition to posterior margin. Posterior margin straight, sometimes slightly concave, smoothly transitioning to ventral margin. First posterior fold absent. Second posterior fold weak. Posterior sulcus weak and shallow. Escutcheon long (EL/L=0.62 ± 0.03), narrow, deep (Figs 2C– D, 4A–D, Table 1). Auricle absent. Lunule long (LL/L= 0.39 ±0.04), wide, flat, demarcated by weak, rounded ridges (Figs 2C–D, 4A–B, E, Table 1). Ligament opisthodetic, visible externally for more than a half of its total length, thick, evenly curved, long, three-fourths the length of escutcheon, lying in shallow, slightly curved, wide groove at surface of hinge plate (Figs 2C, 3F, J, 4A, C–D). Prodissoconch large (length 235–250 µm), ovate in outline, with 5 thin, lamellated folds, extending from high and sharp apex, located in midline of prodissoconch (Figs 3H, 4F). Hinge plate thick, edentulous, with numerous, shallow pits (to 20 µm) under beaks (Fig. 3F–G, J–K). Muscle scars indistinct. GROSS ANATOMY. Mantle edge thick, no obvious proliferation of glandular tissue on its anterior inner edge. Mantle fused posteriorly forming small exhalant aperture below posterior adductor muscle (Fig. 5A–C). Anterior adductor muscle elongate (Fig. 5J). Posterior adductor muscle small, ovate, 2 × as short and as narrow as anterior adductor muscle. Ctenidium wide, consisting of two demibranchs with fully reflected filaments (up to 80 filaments in specimen 7.5 mm in length); outer demibranch approximately half the size of inner demibranch. Demibranchs covering greater part of lateral body pouches (Fig. 5A–B). Labial palps relatively large (to 0.9 mm length) (Fig. 5F). Lateral body pouches large, extensively lobed; each lobe is a short and thick process; each pouch connecting to body by a rounded neck (Fig. 5B, E). Kidneys large, dorsoventrally elongated along posterodorsal shell margin, with numerous, red-brown or yellow, small (to 30 µm in diameter), different-size granules (Fig. 5G). Alimentary system with short oesophagus leading to a relatively large, elongate stomach; combined style sac and midgut strongly curved; hind gut forming anterior, deep, narrow loop producing rounded distinct angle, passing through heart and running posteriorly dorsal to kidney and posterior adductor muscle, opening at ventral side of posterior adductor muscle (Fig. 5H–J). Foot long, vermiform, distally bulbous, with muscular ring at junction with visceral mass. Bulbous portion not divided into two distinct parts; surface with numerous wrinkles; heel absent (Fig. 5B, D). Anterior and posterior pedal retractors wide, short, well developed. Variability In small specimens (up to 3 mm in shell length) the shell is relatively low, angular, with a strongly curved and anteriorly drawn-out ventral margin; the anterodorsal and posterodorsal margins gently sloping from beaks; the anterodorsal margin is concave (Fig. 2J). The shell shape and proportions, the length of the lunule and escutcheon, the degree of bending of shell margins vary among larger specimens (Fig. 2A–I, Table 1). Some of large specimens have a shell rather elongated dorsoventrally (Fig. 2I). Distribution and habitat Oceanic slope of the Kamchatka Peninsula (53°05.4′ N, 161°55.2′ E – 53°07′ N, 161°56.1′ E), 4890– 4984 m depth, abyssal plain adjacent to the southern part of the Kuril-Kamchatka Trench (39°42.49′ N, 147°09.37′ E – 41°16′ N, 147°27.7′ E), 5210–5351 m depth (bottom temperature (6–8 m above bottom) 1.5–1.6 °C, salinity 34.7‰, oxygen 7.71–7.72 ml. l−1) (Brandt et al. 2015), and in the Kuril-Kamchatka Trench (45°56.570′ N, 152°51.185′ E – 45°56.834′ N, 152°50.943′ E), 6164–6204 m depth (Fig. 6). Differential diagnosis The genus Parathyasira currently includes 14 species (WoRMS Editorial Board 2022), among which 6 species (P. resupina Iredale, 1930, P. neozelanica Iredale, 1930, P. verconis (Cotton & Godfrey, 1938), P. granulosa (Monterosato, 1874), P. subcircularis (Payne & Allen, 1991), and P. bamberi P.G. Oliver, 2015) have a shell microsculpture consisting of calcareous spines arranged in dense radial rows (Oliver 2015). The new species described herein lacks this microsculpture. Parathyasira coani sp. nov. differs from most of other species of Parathyasira by having an anteriorly drawn-out shell, a flat, a nonexcavated lunule, and a large prodissoconch with sculpture of lamellated folds (Table 2). The new species is most similar to Parathyasira biscayensis (Payne & Allen, 1991) described from two specimens found in the Bay of Biscay (Atlantic Ocean) (4720 m) (Payne & Allen 1991) (Fig. 7A– C). However, in contrast to P. biscayensis, P. coani sp. nov. has only about half as many filaments in the gills, compared to almost similar-sized specimens of the former species, up to 80 (specimen 7.5 mm in length) vs 150 (specimen 8.2 mm in length), respectively, and a longer ligament. Moreover, in P. biscayensis the lunule is medially elevated, while in P. coani the lunule is flat. Parathyasira coani is similar to Parathyasira fragilis Kamenev, 2020 from which it differs in having a thick, opaque and white shell, a long and thick ligament, the greater part of which is well visible externally, the foot with a bulbous distal portion not differentiated into two parts, and a different sculpture of the prodissoconch (Table 2). Parathyasira coani is also similar to Parathyasira dearborni (Nicol, 1965) in shell shape and ratios, as well as in the shape of the lunule and escutcheon, but differs by lacking microscopic irregular corrugations and pustules on the shell and a second siphonal opening, by having a larger (more than 2 ×) prodissoconch with a different sculpture (Table 2), and the lateral body pouches with a greater number of folds. Remarks To date, the benthic fauna of the Kuril-Kamchatka Trench is the most studied one, compared to other oceanic trenches (Belyaev 1989; Brandt et al. 2019, 2020), and the largest number of macrofaunal samples were collected with various sampling gears in its hadal zone. As a result of studying the entire material of bivalves collected in this trench (Kamenev 2019), P. coani sp. nov. was recorded only in two samples collected from the uppermost part of the trench slope at a depth of more than 6000 m. Outside of the Kuril-Kamchatka Trench, P. coani was found in many samples from the abyssal zone at depths less than 6000 m. Therefore, this species is probably a predominantly abyssal one and depths of slightly more than 6000 m are the lower limit of its vertical distribution. Apart from P. coani, seven bivalve species have a similar vertical distribution in the Kuril-Kamchatka Trench area (Kamenev 2019). As shown in the example of distribution of many macrofaunal species, depths of 6000–7000 m are a zone of transition between abyssal and hadal faunas and are the lower and upper boundaries of the vertical distribution of many abyssal and hadal macrofauna species, respectively (Belyaev 1989; Jamieson 2015; Kamenev 2019; Kamenev et al. 2022)., Published as part of Kamenev, Gennady M., 2023, Three new deep-sea species of Thyasiridae (Mollusca: Bivalvia) from the northwestern Pacific Ocean, pp. 87-119 in European Journal of Taxonomy 856 on pages 90-101, DOI: 10.5852/ejt.2023.856.2031, http://zenodo.org/record/7569595, {"references":["Kamenev G. M. 2015. Composition and distribution of bivalves of the abyssal plain adjacent to the KurilKamchatka Trench (Pacific Ocean). Deep-Sea Research Part II: Topical Studies in Oceanography 111: 188 - 197. https: // doi. org / 10.1016 / j. dsr 2.2014.08.005","Kamenev G. M. 2019. Bivalve mollusks of the Kuril-Kamchatka Trench, Northwest Pacific Ocean: species composition, distribution and taxonomic remarks. Progress in Oceanography 176: 102127. https: // doi. org / 10.1016 / j. pocean. 2019.102127","Kamenev G. M. 2020. Three new deep-sea species of Thyasiridae (Mollusca: Bivalvia) from the abyssal plain of the northwestern Pacific Ocean and hadal depths of the Kuril-Kamchatka Trench. PeerJ 8: e 10405. https: // doi. org / 10.7717 / peerj. 10405","Dall W. H. 1901. Synopsis of the lucinacea and of the American species. Proceedings of the United States National Museum 23: 779 - 833. https: // doi. org / 10.5479 / si. 00963801.23 - 1237.779","Zelaya D. G. 2009. The genera Thyasira and Parathyasira in the Magellan region and adjacent Antarctic waters (Bivalvia: Thyasiridae). Malacologia 51: 271 - 290. https: // doi. org / 10.4002 / 040.051.0204","Nicol D. 1965. A new Thyasira (Pelecypoda) from the Ross Sea, Antarctica. Nautilus 78: 79 - 80. https: // doi. org / 10.5962 / bhl. part. 24542","Lubinsky I. 1976. Thyasira dunbari n. sp. (Bivalvia: Thyasiridae) from the Canadian Arctic Archipelago. Journal of the Fisheries Research Board of Canada 33: 1667 - 1670. https: // doi. org / 10.1139 / f 76 - 212","Oliver P. G. & Killeen I. J. 2002. The Thyasiridae (Mollusca: Bivalvia) of the British Continental Shelf and North Sea oil fields: an identification manual. Studies in Marine Biodiversity and Systematics from the National Museum of Wales. BIOMOR Reports 3: 1 - 73.","Verrill A. E. & Bush K. J. 1898. Revision of the deep-water Mollusca of the Atlantic coast of North America, with descriptions of new genera and species. Part. I. Bivalvia. Proceedings of the United States National Museum 20: 775 - 901. https: // doi. org / 10.5479 / si. 00963801.20 - 1139.775","Payne C. M. & Allen J. A. 1991. The morphology of deep sea Thyasiridae (Mollusca: Bivalvia) from the Atlantic Ocean. Philosophical Transactions of the Royal Society, Series B 334 (1272): 481 - 562. https: // doi. org / 10.1098 / rstb. 1991.0128","Smith E. A., Thomson C. W. & Murray J. 1885. Report on the Lamellibranchiata collected by H. M. S. Challenger during the years 1873 - 76. In: Thomson C. W. & Murray J. (eds) Report of the Scientific Results of the Voyage of H. M. S. Challenger During the Years 18730 - 76 Under the Command of Captain George S. Nares and Captain Frank Tourle Thomson. Zoology. Neill, Edinburg / Dublin. https: // doi. org / 10.5962 / bhl. title. 109677","Brandt A. & Malyutina MV. 2015. The German-Russian deep-sea expedition KuramBio (Kurile Kamchatka biodiversity studies) on board of RV Sonne in 2012 following the footsteps of the legendary expeditions with RV Vityaz. Deep-Sea Research Part II: Topical Studies in Oceanography 111: 1 - 9. https: // doi. org / 10.1016 / j. dsr 2.2014.11.001","WoRMS Editorial Board. 2022. World Register of Marine Species. Available from https: // www. marinespecies. org [accessed 28 May 2022]. https: // doi. org / 10.14284 / 170","Oliver P. G. 2015. Deep-water Thyasiridae (Mollusca: Bivalvia) from the Oman Margin, Arabian Sea, new species and examples of endemism and cosmopolitanism. Zootaxa 3995 (1): 252 - 263. https: // doi. org / 10.11646 / zootaxa. 3995.1.21","Okutani T. 1968. Bathyal and abyssal Mollusca trawled from Sagami Bay and the south off Boso Peninsula by the R / V Soyo-Maru, 1965 - 1967. Bulletin of the Tokai Regional Fisheries Research Laboratory 56: 7 - 55.","Belyaev G. M. 1989. Deep-Sea Oceanic Trenches and their Fauna. Nauka Press, Moscow. [In Russian.]","Brandt A., Alalykina I., Brix S., Brenke N., Blazewicz M., Golovan O. A., Johannsen N., Hrinko A. M., Jazdzewska A. M., Jeskulke K., Kamenev G. M., Lavrenteva A. V., Malyutina M. V., Riehl T. & Lins L. 2019. Depth zonation of Northwest Pacific deep-sea macrofauna. Progress in Oceanography 176: 102131. https: // doi. org / 10.1016 / j. pocean. 2019.102131","Brandt A., Brix S., Riehl T. & Malyutina M. 2020. Biodiversity and biogeography of the abyssal and hadal Kuril-Kamchatka trench and adjacent NW Pacific deep-sea regions. Progress in Oceanography 181: 102232. https: // doi. org / 10.1016 / j. pocean. 2019.102232","Jamieson A. J. 2015. The Hadal Zone: Life in the Deepest Oceans. Cambridge University Press, Cambridge. https: // doi. org / 10.1017 / CBO 9781139061384","Kamenev G. M., Mordukhovich V. V., Alalykina I. L., Chernyshev A. V. & Maiorova A. S. 2022. Macrofauna and nematode abundance in the abyssal and hadal zones of interconnected deep-sea ecosystems in the Kuril Basin (Sea of Okhotsk) and the Kuril-Kamchatka Trench (Pacific Ocean). Frontiers in Marine Science 9: 812464. https: // doi. org / 10.3389 / fmars. 2022.812464"]}

Genus Parathyasira Iredale, 1930 Type species Parathyasira resupina Iredale, 1930., Published as part of Kamenev, Gennady M., 2023, Three new deep-sea species of Thyasiridae (Mollusca: Bivalvia) from the northwestern Pacific Ocean, pp. 87-119 in European Journal of Taxonomy 856 on page 90, DOI: 10.5852/ejt.2023.856.2031, http://zenodo.org/record/7569595

The Thyasiridae is one of the species-richest families in the abyssal and hadal zones of the northwestern Pacific Ocean. Many thyasirid species dominate benthic communities in terms of abundance and play an important role in the functioning of deep-sea ecosystems. Most of the thyasirid species in the region are new to science and have not been described. Based on the material collected from 1954 to 2016 by seven deep-sea expeditions, three new species of Thyasiridae (Parathyasira coani sp. nov., P. pauli sp. nov., and Thyasira kharkovensis sp. nov.) are described from the abyssal and hadal zones (3210–7540 m depth) of the Sea of Okhotsk, the Bering Sea, as well as the Kuril-Kamchatka and Japan trenches. The new species are remarkable among their congeners due to the combination of the following characters: an obliquely-rhomboidal shell with a weak and shallow posterior sulcus and a large prodissoconch with sculpture of lamellated folds. Comparisons with related species are provided.

Genus Thyasira Lamarck, 1818 Type species Tellina flexuosa Montagu, 1803., Published as part of Kamenev, Gennady M., 2023, Three new deep-sea species of Thyasiridae (Mollusca: Bivalvia) from the northwestern Pacific Ocean, pp. 87-119 in European Journal of Taxonomy 856 on page 107, DOI: 10.5852/ejt.2023.856.2031, http://zenodo.org/record/7569595

Thyasira kharkovensis sp. nov. urn:lsid:zoobank.org:act: 5E4F1FDC-5A7D-47BA-9FE5-B1F700D80C60 Figs 6, 12–16, Table 4 Parathyasira sp. 1 – Kamenev 2018a: 234. Diagnosis Shell small (to 7.4 mm in length), obliquely pyriform, transparent, flattened, drawn out anteriorly. Sculpture of thin, commarginal riblets and weak undulations. Posterior folds weak. Posterior sulcus weak, as a flattened, narrow area. Escutcheon long, shallow. Auricle low. Lunule short, flat, weakly defined. Ligament partially visible externally, long. Prodissoconch large (to 200 µm), with 7 thin, lamellated folds, radiating from short, plicate ridge. Lateral body pouches large, extensively lobed. Foot long, distally bulbous; bulbous portion not divided into two parts; heel distinct. Etymology The species epithet honors the city of Kharkov, where I was born, grew up, and was educated. Material examined Holotype RUSSIA • Sea of Okhotsk, Kuril Basin floor; 48°02.512′ N, 149°59.911′ E –48°02.353′ N, 149°59.805′ E; depth 3350 m; 21 Jul. 2015; K.V. Minin leg.; Agassiz trawl, RV Akademik M.A. Lavrentyev, cruise no. 250, stn. 6-9; MIMB 43824. Paratypes RUSSIA • 2 specs; same collection data as for holotype; MIMB 43825 • 2 specs; same collection data as for holotype; SMF 367802. Other material RUSSIA – Bering Sea • 6 specs; 55°13.2′ N, 167°29.07′ E –55°12′ N, 167°26.7′E; depth 3957 m; 31 Jul. 1990; L.I. Moskalev and S.V. Galkin leg.; Sigsbee trawl, RV Akademik Mstislav Keldysh, cruise no. 22, stn. 2309; IORAS OBF collection Cat. BIV00045 • 6 specs; same locality as for preceding; 55°36.1′ N, 167°23.04′ E –55°35′ N, 167°24.5′E; depth 4294 m; 5 Aug. 1990; L.I. Moskalev and S.V. Galkin leg.; Sigsbee trawl, RV Akademik Mstislav Keldysh, cruise no. 22, stn. 2316; IORAS OBF collection Cat. BIV00046 – Sea of Okhotsk • 1 spec.; 46°08.745′ N, 145°59.760′ E; depth 3304 m; 9 Jul. 2015; G.M. Kamenev leg.; box corer, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 1-3; MIMB 43826 • 2 specs; same locality as for preceding; 46°08.875′ N, 145°59.336′ E –46°08.839′ N, 145°59.165′ E; depth 3307 m; 10 Jul. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 1-8; MIMB 43827 • 3 specs; same locality as for preceding; 46°09.037′ N, 146°00.465′ E –46°09.020′ N, 146°00.269′ E; depth 3307 m; 10 Jul. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 1-9; MIMB 43828 • 7 specs; same locality as for preceding; 46°40.961′ N, 147°28.283′ E –46°40.877′ N, 147°28.499′ E; depth 3353– 3352 m; 13 Jul. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 2-7; MIMB 43829 • 2 specs; same locality as for preceding; 47°12.046′ N, 149°36.901′ E; depth 3366 m; 16 Jul. 2015; G.M. Kamenev leg.; box corer, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 4-4; MIMB 43830 • 5 specs; same locality as for preceding; 47°12.132′ N, 149°37.136′ E –47°11.991′ N, 149°36.990′ E; depth 3366 m; 17 Jul. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 4-9; MIMB 43831 • 4 specs; same locality as for preceding; 47°12.039′ N, 149°36.950′ E –47°12.177′ N, 149°36.726′ E; depth 3366 m; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 4–10; 17 Jul. 2015; MIMB 43832 • 1 spec.; same locality as for preceding; 48°03.258′ N, 150°00.581′ E –48°03.141′ N, 150°00.432′ E; depth 3347 m; 20 Jul. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 6-6; MIMB 43833 • 1 spec.; same locality as for preceding; 48°03.234′ N, 150°00.468′ E –48°03.078′ N, 150°00.351′ E; depth 3350–3351 m; 21 Jul. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 6-7; MIMB 43834 • 5 specs; same locality as for preceding; 48°02.512′ N, 149°59.911′ E –48°02.353′ N, 149°59.805′ E; depth 3350 m; 21 Jul. 2015; K.V. Minin leg.; Agassiz trawl, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 6-9; MIMB 43835 • 2 specs; same locality as for preceding; 46°56.952′ N, 151°04.975′ E; depth 3300 m; 21 Jul. 2015; G.M. Kamenev leg.; box corer, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 7-1; MIMB 43836 • 7 specs; same locality as for preceding; 46°56.556′ N, 151°05.013′ E –46°56.753′ N, 151°05.017′ E; depth 3299 m; 22 Jul. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 7-3; MIMB 43837 • 3 specs; same locality as for preceding; 46°57.466′ N, 151°05.068′ E –46°57.326′ N, 151°05.050′ E; depth 3300 m; 22 Jul. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 7–4; MIMB 43838 • 6 specs; same locality as for preceding; 45°36.792′ N, 146°22.589′ E –45°36.902′ N, 146°22.484′ E; depth 3210 m; 1 Aug. 2015; A. Brandt leg.; epibenthic sledge, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 11-6; MIMB 43839. PACIFIC OCEAN – oceanic slope of the Kuril Islands • 2 specs; 46°16.082′ N, 152°02.060′ E; depth 3432 m; 27 Jul. 2015; G.M. Kamenev leg.; box corer, RV Akademik Mstislav Keldysh, cruise no. 71, stn. 9-1; MIMB 43840. Description SHELL. Small (to 7.4 mm in length and 7.6 mm in height), obliquely-ovate to obliquely pyriform, equivalve, subequilateral, grayish white, very thin, fragile, translucent, flattened (W/L=0.48 ± 0.04), slightly longer than high (H/L=0.98 ± 0.03), drawn out anteriorly; small quantities of ferruginous deposit may adhere to anterodorsal shell margin (Figs 12–13, Table 4). Periostracum thin, transparent, adherent. Sculpture of thin, commarginal riblets and weak, narrow, irregular undulations (Fig. 12F). Central part of shell with microscopic (to 3 µm), irregular, densely spaced granules (Fig. 14C–D). Beaks small, raised, pointed, prosogyrate, slightly anterior to midline (A/L=0.45 ±0.03). Anterodorsal shell margin straight, sloping rather steeply from beaks, smoothly transitioning to anterior margin. Anterior shell margin slightly convex, smoothly transitioning to ventral margin. Ventral margin strongly curved. Posterodorsal shell margin slightly convex, sloping rather steeply from beaks, forming weak, rounded angle at transition to posterior margin. Posterior shell margin straight or slightly convex, smoothly transitioning to ventral margin. Posterior folds weak. Posterior sulcus weak, shallow, as flattened, narrow area. Escutcheon long (EL/L=0.54 ±0.05), narrow, shallow, demarcated by low ridges (Figs 13B–C, E, 15A–D). Auricle weak, low, only slightly projecting (Figs 14E, 15C–D). Lunule relatively short (LL/L=0.34 ± 0.05), flat (Fig. 13B–D). Ligament opisthodetic, visible externally for more than half of its length, thin, almost as long as entire length of escutcheon, lying in shallow, almost straight, narrow groove in hinge plate (Fig. 14F–I). Prodissoconch large (length 189–200 µm), distinctly separated from dissoconch, ovate in outline, with 7 thin, lamellated folds (posterior fold sometimes bifurcated, central fold sometimes indistinct), radiating from a short, higher and wider, plicate ridge, located in mid-line of prodissoconch (Fig. 15E–F). Hinge plate thin, edentulous, sometimes with numerous, shallow, elongate pits (to 50 µm) beneath beak and ligamental groove (Fig. 14J). Muscle scars indistinct. GROSS ANATOMY. Mantle thin, transparent; mantle edge free except at junction with gill axis (Fig. 16). Anterior adductor muscle large, strongly elongated, curved almost parallel to anterior shell margin. Posterior adductor muscle 3 × as short as anterior, oval. Ctenidium thin, wide, both demibranchs with fully reflected filaments (up to 60 filaments in specimen 5.2 mm in length); outer demibranch about half depth of inner demibranch (Fig. 16A, D–E). Labial palps relatively large (to 0.8 mm in length) (Fig. 16B). Lateral body pouches large, extensively lobed; numerous lobes thick, cloven or single; each pouch connecting to body by a wide neck (Fig. 16D–E). Kidneys extremely large, dorsoventrally elongated along entire posterodorsal shell margin, with numerous, pink or orange, large (to 100 µm in diameter), different-size granules well visible through transparent shell (Figs 14, 16D–H). Oesophagus short; stomach large, strongly elongated; combined style sac and midgut strongly curved, lies over stomach; hind gut forming anterior loop dorsal to style sac, running posteriorly dorsal to kidney and posterior adductor muscle. Food remains present in hindgut (Fig. 16G–H). Foot long, vermiform, distally bulbous, with muscular ring at junction with visceral mass. Bulbous tip not divided into two parts; surface with numerous, longitudinal, curved gathers; heel small (Fig. 16C, E). Anterior and posterior pedal retractors wide, long, well developed. Variability In small specimens (up to 5 mm in shell length), the shell is relatively low, angulate, with a strongly curved and anteriorly drawn-out ventral margin, and weakly defined lunule with valve margin junction raised; anterodorsal and posterodorsal margins are sloped more gently from beaks (Fig. 13G–H). In larger specimens, the shell shape and proportions do not vary. Distribution and habitat Kuril Basin floor (Sea of Okhotsk) (45°36.792′ N, 146°22.589′ E – 48°03.258′ N, 150°00.581′ E), 3210– 3366 m depth (bottom temperature (1 m above bottom) 1.85–1.88°C, salinity 34.6%, oxygen 1.73– 1.87 ml. l−1) (Kamenev 2018; Kamenev et al. 2022), Commander Basin floor (Bering Sea) (55°12′ N, 167°26.7′ E – 55°36.1′ N, 167°23.04′ E), 3957–4294 m depth, and oceanic slope of the Kuril Islands opposite the Bussol Strait (46°16.082′ N, 152°02.060′ E), 3432 m depth (Fig. 6). Differential diagnosis The new species described herein differs from the vast majority of species of Thyasira in having an obliquely-pyriform, anteriorly drawn-out, non-sulcate shell, with very narrow, indistinct posterior folds, large prodissoconch with thin, lamellated folds, strongly elongated, narrow adductor muscles, and a heel of foot. Thyasira kharkovensis sp. nov. is most similar in shell shape to Axinulus obliquus Okutani, 1968 (Fig. 7D–J) clearly differing in having a narrower escutcheon and thinner ligament, a shorter, indistinct and non-excavated lunule. Axinulus obliquus was described as Axinulus obliqua Okutani, 1968 following only examination of the morphology of the shell (Okutani 1968). The main character that distinguishes Axinulus from most genera in the family Thyasiridae is the presence of a single demibranch in the ctenidium (Oliver & Killeen 2002; Zelaya 2010; Oliver 2015; Kamenev 2020). I assumed that very probably the ctenidium of this species consists of two demibranchs, and after further anatomical investigation A. obliquus could be placed in the genus Thyasira (Kamenev 2020). Based on my assumption, A. obliquus was listed in the WoRMS Editorial Board (2022) under the name of Thyasira obliqua (Okutani, 1968). On the other hand, the WoRMS Editorial Board (2022) classifies the status of A. obliquus as a “taxon inquirendum”. Unfortunately, it is currently not possible to examine the gills of A. obliquus, because only dry material is deposited at the NSMT (Dr Hiroshi Saito, pers. comm.). Therefore, the species still falls under the category of a taxon of uncertain taxonomic validity. Thyasira kharkovensis sp. nov. resembles T. obsoleta (Verrill & Bush, 1898), T. succisa (Jeffreys, 1876), and T. debilis (Thiele, 1912), from which it differs in having a more flattened, thin and fragile shell, a longer escutcheon, a lower auricle, a longer well-visible externally ligament, and a much larger prodissoconch (the prodissoconch length of T. obsoleta, T. succisa, and T. debilis does not exceed 165µm) (Payne & Allen 1991; Oliver & Killeen 2002; Zelaya 2009) with lamellated folds. In addition, the new species described herein lacks the pseudocardinal tubercle in the right valve described for T. succisa and T. debilis (Payne & Allen 1991; Oliver & Killeen 2002; Zelaya 2009). On the whole, because of its obliquely pyriform, non-sulcate shell with narrow, indistinct posterior folds T. kharkovensis sp. nov. does not correspond to the diagnosis of the genus Thyasira. Consequently, T. kharkovensis is assigned to Thyasira sensu lato. Remarks Thyasira kharkovensis sp. nov. was recorded in the Sea of Okhotsk and on the oceanic slope of the Kuril Islands at 9 of 10 stations at depths less than 4000 m. However, this species was not found any of the 24 stations conducted in the Kuril-Kamchatka Trench area by the KuramBio (2012), SokhoBio (2015) and KuramBio II (2016) expeditions at depths greater than 5000 m (Kamenev 2015, 2018 a, 2019). Probably, T. kharkovensis sp. nov. does not occur at depths greater than 5000 m, preferring the upper abyssal zone. Previous studies showed that the deep-sea benthic fauna of the Sea of Okhotsk is closely related to the western Pacific fauna. Many species from various groups of animals that were discovered on the Kuril Basin floor (Sea of Okhotsk) were also found at the Pacific side of the Kuril Islands (e.g., Alalykina 2018, Downey et al. 2018; Fukumori et al. 2018; Kamenev 2018a; Malyutina & Brandt 2018; Mironov et al. 2018; Ostermair et al. 2018). A number of studies showed that the deep-sea Pacific fauna mainly penetrates into the Sea of Okhotsk through the deep straits of the Kuril Islands, primarily through the wide and deepest Bussol Strait (depth of 2318 m) (Ushakov 1953; Savilov 1961; Kamenev 2018a; Mironov et al. 2018). Most of deep-sea bivalve species from the Sea of Okhotsk were found in the Pacific Ocean to depths of 4000 m (Kamenev 2018a; Kamenev et al. 2022). In the Pacific Ocean, at depths greater than 5000 m, only two out of 25 species found in the abyssal zone of the Sea of Okhotsk were recorded (Kamenev 2018 a, 2019). Perhaps, T. kharkovensis lives in the upper abyssal zone on the oceanic slopes of the Kuril Islands and the Kamchatka Peninsula. It also penetrated into the Bering Sea through the wide and deep Kamchatka Strait (depths of more than 4000 m) and was found on the floor of the Commander Basin located opposite the Kamchatka Strait. The Bering Sea has three deepwater basins (Commander, Bowers, and Aleutian basins) connected to one another. It is possible that T. kharkovensis lives on the floor of all the basins of the Bering Sea and has a continuous distributional range from the Asian to American continent along the Aleutian Islands, inhabiting the slope of the islands. For example, the deep-sea propeamussiid bivalve Catillopecten squamiformis (Bernard, 1978) has a similar geographic and vertical distribution in the northern Pacific (Kamenev 2018b)., Published as part of Kamenev, Gennady M., 2023, Three new deep-sea species of Thyasiridae (Mollusca: Bivalvia) from the northwestern Pacific Ocean, pp. 87-119 in European Journal of Taxonomy 856 on pages 107-114, DOI: 10.5852/ejt.2023.856.2031, http://zenodo.org/record/7569595, {"references":["Kamenev G. M. 2018 a. Bivalve molluscs of the abyssal zone of the Sea of Okhotsk: species composition, taxonomic remarks, and comparison with the abyssal fauna of the Pacific Ocean. Deep-Sea Research Part II: Topical Studies in Oceanography 154: 230 - 248. https: // doi. org / 10.1016 / j. dsr 2.2017.10.006","Kamenev G. M., Mordukhovich V. V., Alalykina I. L., Chernyshev A. V. & Maiorova A. S. 2022. Macrofauna and nematode abundance in the abyssal and hadal zones of interconnected deep-sea ecosystems in the Kuril Basin (Sea of Okhotsk) and the Kuril-Kamchatka Trench (Pacific Ocean). Frontiers in Marine Science 9: 812464. https: // doi. org / 10.3389 / fmars. 2022.812464","Okutani T. 1968. Bathyal and abyssal Mollusca trawled from Sagami Bay and the south off Boso Peninsula by the R / V Soyo-Maru, 1965 - 1967. Bulletin of the Tokai Regional Fisheries Research Laboratory 56: 7 - 55.","Oliver P. G. & Killeen I. J. 2002. The Thyasiridae (Mollusca: Bivalvia) of the British Continental Shelf and North Sea oil fields: an identification manual. Studies in Marine Biodiversity and Systematics from the National Museum of Wales. BIOMOR Reports 3: 1 - 73.","Zelaya D. G. 2010. New species of Thyasira, Mendicula, and Axinulus (Bivalvia, Thyasiroidea) from Sub- Antarctic and Antarctic waters. Polar Biology 33: 607 - 616. https: // doi. org / 10.1007 / s 00300 - 009 - 0736 - 9","Oliver P. G. 2015. Deep-water Thyasiridae (Mollusca: Bivalvia) from the Oman Margin, Arabian Sea, new species and examples of endemism and cosmopolitanism. Zootaxa 3995 (1): 252 - 263. https: // doi. org / 10.11646 / zootaxa. 3995.1.21","Kamenev G. M. 2020. Three new deep-sea species of Thyasiridae (Mollusca: Bivalvia) from the abyssal plain of the northwestern Pacific Ocean and hadal depths of the Kuril-Kamchatka Trench. PeerJ 8: e 10405. https: // doi. org / 10.7717 / peerj. 10405","WoRMS Editorial Board. 2022. World Register of Marine Species. Available from https: // www. marinespecies. org [accessed 28 May 2022]. https: // doi. org / 10.14284 / 170","Verrill A. E. & Bush K. J. 1898. Revision of the deep-water Mollusca of the Atlantic coast of North America, with descriptions of new genera and species. Part. I. Bivalvia. Proceedings of the United States National Museum 20: 775 - 901. https: // doi. org / 10.5479 / si. 00963801.20 - 1139.775","Payne C. M. & Allen J. A. 1991. The morphology of deep sea Thyasiridae (Mollusca: Bivalvia) from the Atlantic Ocean. Philosophical Transactions of the Royal Society, Series B 334 (1272): 481 - 562. https: // doi. org / 10.1098 / rstb. 1991.0128","Zelaya D. G. 2009. The genera Thyasira and Parathyasira in the Magellan region and adjacent Antarctic waters (Bivalvia: Thyasiridae). Malacologia 51: 271 - 290. https: // doi. org / 10.4002 / 040.051.0204","Kamenev G. M. 2015. Composition and distribution of bivalves of the abyssal plain adjacent to the KurilKamchatka Trench (Pacific Ocean). Deep-Sea Research Part II: Topical Studies in Oceanography 111: 188 - 197. https: // doi. org / 10.1016 / j. dsr 2.2014.08.005","Brandt A., Alalykina I., Brix S., Brenke N., Blazewicz M., Golovan O. A., Johannsen N., Hrinko A. M., Jazdzewska A. M., Jeskulke K., Kamenev G. M., Lavrenteva A. V., Malyutina M. V., Riehl T. & Lins L. 2019. Depth zonation of Northwest Pacific deep-sea macrofauna. Progress in Oceanography 176: 102131. https: // doi. org / 10.1016 / j. pocean. 2019.102131","Downey R. V., Fuchs M. & Janussen D. 2018. Unusually diverse, abundant and endemic deep-sea sponge fauna revealed in the Sea of Okhotsk (NW Pacific Ocean). Deep Sea Research Part II: Topical Studies in Oceanography 154: 47 - 58. https: // doi. org / 10.1016 / j. dsr 2.2018.02.005","Fukumori H., Hasegawa K. & Kano Y. 2018. Abyssal gastropods in the Sea of Okhotsk (Vetigastropoda and Caenogastropoda). Deep Sea Research Part II: Topical Studies in Oceanography 154: 187 - 196. https: // doi. org / 10.1016 / j. dsr 2.2017.09.013","Malyutina M. V. & Brandt A. 2018. First records of deep-sea Munnopsidae (Isopoda: Asellota) from the Kuril Basin of the Sea of Okhotsk, with description of Gurjanopsis kurilensis sp. nov. Deep-Sea Research Part II: Topical Studies in Oceanography 154: 275 - 291. https: // doi. org / 10.1016 / j. dsr 2.2017.12.006 Malyutina M. V., Chernyshev A. V. & Brandt A. 2018. Introduction to the SokhoBio (Sea of Okhotsk Biodiversity Studies) expedition 2015. Deep-Sea Research Part II: Topical Studies in Oceanography 154: 1 - 9. https: // doi. org / 10.1016 / j. dsr 2.2018.08.012","Mironov A. N., Minin K. V., Dilman A. B. & Smirnov I. S. 2018. Deep-sea echinoderms of the Sea of Okhotsk. Deep-Sea Research Part II: Topical Studies in Oceanography 154: 342 - 357. https: // doi. org / 10.1016 / j. dsr 2.2017.10.003","Ostermair L., Brandt A., Haszprunar G., Jorger K. M. & Bergmeier F. S. 2018. First insights into the solenogaster diversity of the Sea of Okhotsk with the description of a new species of Kruppomenia (Simrothiellidae, Cavibelonia). Deep Sea Research Part II: Topical Studies in Oceanography 154: 214 - 229. https: // doi. org / 10.1016 / j. dsr 2.2017.12.008","Ushakov P. V. 1953. The Fauna of the Sea of Okhotsk and Conditions of Life in it. Academy of Sciences of USSR Press, Leningrad. [In Russian.]","Savilov A. I. 1961. Ecologic characteristics of the bottom communities of invertebrates in the Okhotsk Sea. Proceedings of P. P. Shirshov Institute of Oceanology 46: 3 - 84. [In Russian.]","Kamenev G. M. 2018 b. Four new species of the family Propeamussiidae (Mollusca: Bivalvia) from the abyssal zone of the northwestern Pacific, with notes on Catillopecten squamiformis (Bernard, 1978). Marine Biodiversity 48: 647 - 676. https: // doi. org / 10.1007 / s 12526 - 017 - 0821 - 1"]}

New data on 52 non-indigenous mollusks in the Eastern Mediterranean Sea is reported. Fossarus sp. (aff. aptus sensu Blatterer 2019), Coriophora lessepsiana Albano, Bakker & Sabelli, sp. nov., Cerithiopsis sp. aff. pulvis, Joculator problematicus Albano & Steger, sp. nov., Cerithiopsis sp., Elachisina sp., Iravadia aff. elongata, Vitrinella aff. Vitrinella sp. 1 (sensu Blatterer 2019), Melanella orientalis, Parvioris aff. dilecta, Odostomia cf. dalli, Oscilla virginiae, Parthenina cossmanni, Parthenina typica, Pyrgulina craticulata, Turbonilla funiculata, Cylichna collyra, Musculus coenobitus, Musculus aff. viridulus, Chavania erythraea, Scintilla cf. violescens, Iacra seychellarum and Corbula erythraeensis are new records for the Mediterranean. An unidentified gastropod, Skeneidae indet., Triphora sp., Hypermastus sp., Sticteulima sp., Vitreolina cf. philippi, Odostomia (s.l.) sp. 1, Henrya (?) sp., and Semelidae sp. are further potential new non-indigenous species although their status should be confirmed upon final taxonomic assessment. Additionally, the status of Dikoleps micalii, Hemiliostraca clandestina comb. nov. and H. athenamariae comb. nov. is changed to non-indigenous, range extensions for nine species and the occurrence of living individuals for species previously recorded from empty shells only are reported. Opimaphora blattereri Albano, Bakker & Sabelli, sp. nov. is described from the Red Sea for comparison with the morphologically similar C. lessepsiana Albano, Bakker & Sabelli, sp. nov. The taxonomic part is followed by a discussion on how intensive fieldwork and cooperation among institutions and individuals enabled such a massive report, and how the poor taxonomic knowledge of the Indo-Pacific fauna hampers non-indigenous species detection and identification. Finally, the hypothesis that the simultaneous analysis of quantitative benthic death assemblages can support the assignment of non-indigenous status to taxonomically undetermined species is discussed.

Species identified as Pillucina are paraphyletic in molecular analyses and a new generic name, Rugalucina , is introduced for a complex of three similar species Rugalucina angela from the northern Indian Ocean and Red Sea, R. vietnamica from South East Asia, and R. munda from northern and north eastern Australia. Lucina concinna from the Red Sea, previously synonymised with P. vietnamica / angela is recognised as a Rugalucina -like species but with a very short anterior adductor scar. Divaricella cypselis from Karachi is similarly now recognised as a distinct species, probably related to Rugalucina but with oblique commarginal sculpture and a short adductor scar. A group of minute Indo-West Pacific lucinids with highly unusual multi-cuspate lateral teeth and previously classified as Pillucina are separated under a new genus Pusillolucina gen. nov., with the description of three new species P. arabica , P. africana , and P. biritika from the Arabian Gulf, Mozambique, and Madagascar. Finally, a new genus, Notocina , is introduced for the small southern Atlantic species, Epicodakia falklandica , shown in molecular analyses to be misplaced at subfamily level and now classified in Lucininae and not Codakiinae with Epicodakia .

A new shallow water species of the lucinid bivalve Pleurolucina is described from Curaçao in the southern Caribbean Sea and compared with known species of the genus from the western Atlantic and eastern Pacific Oceans. Although confused with the Floridian species Pleurolucina leucocyma, it is most similar to the eastern Pacific Pleurolucina undata. As in all studied lucinids, the new species possesses symbiotic bacteria housed in the ctenidia. The shell microstructure is unusual with repeated and intercalated conchiolin layers that have sublayers of ‘tulip-shaped’ calcareous spherules. Predatory drillings by naticid gastropods frequently terminate at the conchiolin layers.

In order to enhance the understanding of Pacific Colombia’s deep-water marine fauna, a benthic research cruise (2012 TUM Offshore 6 and 7) was conducted off the coast of the Department of Nariño, in southern Colombia. Biological, oceanographic and sediment samples from the continental shelf and slope were collected at depths between 350 and 941 m. A new species of Malletia obtained on that cruise is described and compared with other species from the eastern Pacific. Sixteen species of bivalve mollusks (belonging to 12 families and 15 genera) were identified. Five of them were the first records for Pacific Colombia (Jupiterialobula, Limatulasaturna, Lucinomaheroica, Cuspidariapanamensis, and Dallicordiaalaskana). Four of them had geographic distributions that now extend to Tumaco at the southern end of Nariño.

Gibbolucina zelee n. sp. (Fig. 2A-S) urn:lsid:zoobank.org:act: 3994D94E-2522-4608-B837-513901FE615B TYPE MATERIAL. ��� Holotype. Whole shell, L 15.3 mm, H 14.8 mm, T single valve 4.3 mm (MNHN-IM- 2000-33710). Shell in 70% ethanol rehydrated from dried sample. Paratypes. From type locality, MNHN-IM- 2000-33711 figured 1 whole shell with body rehydrated (Fig. 2 E-G) L 12.7 mm, H 12.5 mm; 1 dry shell L 17.7 mm, H 16.2 mm; 2 whole shells, L 10.5 mm, H 10.7 mm, L 9.2 mm, H 9.3 mm; unfigured 2 whole shells with bodies reconstituted, L 16.9 mm, H 17.4 mm, (NHMUK paratype 20170401), L 13.7 mm, H 13.8 mm; unfigured 6 whole shells and 3 single valves. TYPE LOCALITY. ��� Mozambique Channel, Banc de la Z��l��e, Exp��dition BENTHEDI 1977 stn R110, 12��25���6���S, 46��16���2���E, 24 m, 10.IV.1977. Shallow, sandy bottom in the lagoon with dense seagrass beds of Thalassodendron ciliatum (Thomassin et al. 2009). ETYMOLOGY. ��� From French for zealous, named for Banc de la Z��l��e itself named after one of the ships of J. Dumont d���Urville���s Astrolabe Expedition (1837-1840). OTHER MATERIAL EXAMINED. ��� Madagascar. Campagne MIRIKY, stn DW 3255, North of Cap Saint-Andr��, 15��48.2���S, 44��43���E, 36 -39 m, 1 rv (L 15.3 mm) (MNHN). Campagne MIRIKY, stn CP3287, in front of Baie Narendry, 14��33.7���S, 47��27.9���E, 48 -54 m, 1 rv (L 14.6 mm) (MNHN). Toliara, Grand R��cif de Tul��ar, Andeteky area, outer reef slope, lower platform 24 m sand, Thomassin stn TUL 222, 2 lv (1 broken, and L 4.3 mm), 1 rv (L 10.9 mm) (MNHN). Beloza, Grand R��cif de Tul��ar lagoon, inner coral reef, coarse sand Anatomy Limited observations from a rehydrated body (Fig. 2G) show ctenidia with single thickened demibranchs occupying half of mantle cavity, a vermiform foot, simple posterior apertures lacking papillae and short ventral mantle fusion. REMARKS Gibbolucina zelee n. sp. is similar in shape and hinge characters to Gibbolucina trigonula from the Miocene of the Aquitaine Basin, France (Fig. 1O, P). The only other similar species in the Indian Ocean is Megaxinus arabicus Glover & Taylor, 1997 (holotype NMW. Z.1995.009) described from a depth of 58 m off southern Oman. Although this has the overall shape of Gibbolucina species, the hinge has no defined teeth only some irregular folds and the anterior adductor scar is longer, both features similar to Megaxinus transversus (Bronn, 1831)., Published as part of Taylor, John D. & Glover, Emily A., 2018, Hanging on - lucinid bivalve survivors from the Paleocene and Eocene in the western Indian Ocean (Bivalvia: Lucinidae), pp. 123-142 in Zoosystema 40 (7) on page 127, DOI: 10.5252/zoosystema2018v40a7, http://zenodo.org/record/3738245, {"references":["THOMASSIN B., ANDREFOUET S., BOUCHARD J-M., CHARPY L., DINHUT V., QUOD J-P., VICENTE N. & WICKEL J. 2009. - Geyser et Zelee: les sommets d'un meme volcan sous-marins. Univers Maore 12: 22 - 29.","TAYLOR J. D. & GLOVER E. A. 1997. - A chemosymbiotic lucinid bivalve (Bivalvia: Lucinoidea) with periostracal pipes; functional morphology and description of a new genus and species, in WELLS F. E. (ed.), The Marine Flora and Fauna of the Houtman Abrolhos Islands, Western Australia. Western Australian Museum: 335 - 361."]}

Genus Retrolucina n. gen. urn:lsid:zoobank.org:act: DAFC3EBA-0C19-4D63-8248-65A6F761670A TYPE SPECIES. ��� Lucina voorhoevei Deshayes, 1857. Recent, Western Indian Ocean DIAGNOSIS. ��� Shell large L to 80 mm, thin-shelled, ovoid, laterally compressed, longer than high, tapering to anterior and posterior. Umbones low. Posterior dorsal area faintly delineated by shallow sulcus. Sculpture generally smooth with growth lines, sometimes with irregular short anterior and posterior marginal folds. Lunule small, narrow, triangular. Hinge line thin, two small bifurcate cardinal teeth in both valves, lateral teeth absent. Anterior adductor muscle scar long, narrow, curved, extends ventrally to past mid-line of shell, detached and widely separated from pallial line for nearly all of length. Pallial line narrow, entire. Shell interior with fine radial ridges. Inner shell margin smooth. ETYMOLOGY. ��� Latin ���retro��� ��� backwards and lucina in reference to similarity of Eocene species to the sole living species. Feminine. DISTRIBUTION. ��� Western Indian Ocean particularly Mozambique. GEOLOGICAL RANGE. ��� Lucina defrancei Deshayes, 1857, Eocene, Lutetian, Paris Basin (Fig. 6 I-N) is very similar to R. voorhoevei n. comb. in shape, external sculpture, hinge teeth, and characters of anterior adductor muscle scar. REMARKS Previously included in Eomiltha, R. voorhoevei n. comb. differs from the type species by a number of characters. In shell outline, R. voorhoevei n. comb. tapers posteriorly compared with E. contorta that is posteriorly truncate with a shallow sinus. The shell exterior is smooth compared with the more rugose Eomiltha, the anterior adductor scar is thinner and longer and the cardinal teeth smaller. In Retrolucina n. gen. the pallial line lacks the posterior angle towards the posterior adductor scar of Eomiltha contorta. Although Retrolucina n. gen. and Eomiltha are clearly related such morphological differences within living lucinids would suggest different generic placement. This is demonstrated by the various laterally compressed lucinids (e.g. Gloverina, Taylorina, Dulcina, Elliptiolucina) described from Indonesia and Philippines by Cosel & Bouchet (2008) with several of these later corroborated by molecular analyses (Taylor et al. 2011, 2014, 2016). An Eocene (Lutetian) species usually referred to Eomiltha is Lucina defrancei Deshayes, 1857 (synonym L. cuvieri Bayan, 1870) from the Paris Basin (Figs 6 I-N; 7C, D) it is very similar to Retrolucina voorhoevei n. comb. in shell characters and we regard it as congeneric and an antecedent. Despite an extensive literature and collection search we failed to find any species resembling R. defrancei and R. voorhoevei n. comb. recorded from deposits between the Eocene and present day. Further back in geological time we previously (Taylor & Glover 2000, 2006) compared Illiona prisca (Hisinger, 1837) from the Silurian of Gotland, Sweden with R. voorhoevei n. comb., it has a similar flat-shelled, elongate-ovate shape and internally has a very long anterior adductor muscle scar that extends posteriorly to the midline of the shell. The resemblance in shape is remarkable but, in the absence of any fossil record of similar forms from the later Palaeozoic through the Mesozoic, likely results from morphological convergence rather than phylogenetic continuity., Published as part of Taylor, John D. & Glover, Emily A., 2018, Hanging on - lucinid bivalve survivors from the Paleocene and Eocene in the western Indian Ocean (Bivalvia: Lucinidae), pp. 123-142 in Zoosystema 40 (7) on pages 132-133, DOI: 10.5252/zoosystema2018v40a7, http://zenodo.org/record/3738245, {"references":["DESHAYES G. P. 1857. - Note sur une nouvelle lucine, et description de l'espece. Journal de Conchyliologie 6: 104 - 107.","COSEL R. VON & BOUCHET P. 2008. - Tropical deep-water lucinids (Mollusca: Bivalvia) from the Indo-Pacific: essentially unknown, but diverse and occasionally gigantic, in HEROS V., COWIE R. & BOUCHET P. (eds) Tropical Deep Sea Benthos, volume 25. Museum national d'Histoire naturelle, Paris, 806 p. (Memoires du Museum national d'Histoire naturelle; 196): 115 - 213.","TAYLOR J. D., GLOVER E. A., SMITH L., DYAL P. & WILLIAMS S. T. 2011. - Molecular phylogeny and classification of the chemosymbiotic bivalve family Lucinidae (Mollusca: Bivalvia). Zoological Journal of the Linnean Society 163: 15 - 49. https: // doi. org / 10.1111 / j. 1096 - 3642.2011.00700. x","TAYLOR J. D., GLOVER E. A. & WILLIAMS S. T. 2014. - Diversification of chemosymbiotic bivalves: origins and relationships of deeper water Lucinidae. Biological Journal of the Linnean Society 111: 401 - 420. https: // doi. org / 10.1111 / bij. 12208","TAYLOR J. D., GLOVER E. A., SMITH L., IKEBE C. & WILIAMS S. T. 2016. - New molecular phylogeny of Lucinidae: increased taxon base with focus on tropical Western Atlantic species (Mollusca: Bivalvia). Zootaxa 4196 (3): 381 - 398. https: // doi. org / 10.11646 / zootaxa. 4196.3.2","COSSMANN M. & PEYROT A. 1912. - Conchologie neogenique de l'Aquitaine. Actes de la Societe linneenne de Bordeaux 65 (4): 179 - 333.","VOKES H. E. 1969 b. - Notes on the fauna of the Chipola Formation - A new species of Eomiltha (Mollusca: Bivalvia). Tulane Studies in Geology and Paleontology 7: 126 - 130.","TAYLOR J. D. & GLOVER E. A. 2000. - Nomenclatural rectifications for Indo-Pacific Lucinidae. Journal of Conchology 37: 82.","TAYLOR J. D. & GLOVER E. A. 2006. - Lucinidae - the most diverse group of chemosymbiotic molluscs. Zoological Journal of the Linnean Society 148: 421 - 438."]}

Retrolucina voorhoevei (Deshayes, 1857) n. comb. (Figs 6A-H; 7A, B) Lucina voorhoevei Deshayes, 1857: 106, pl. 2, fig, 1. Holotype not located. Dance (1986: 154) lists 1872 sales catalogue of J. Voorhoeve collection where the holotype of Lucina voorhoevei was sold to H. C. R. van Lannep and then later listed in the 1876 sale catalogue of his collection (Jutting 1939) but its subsequent whereabouts is unknown. Lucina mirabilis Dunker, 1865: 77, pl. 26, figs 7-9. Gibbolucina (Eomiltha) voorhoevei ��� Chavan 1938: 93. ��� Kilburn 1974: 343, figs 6, 7. Eomiltha voorhoevei ��� Oliver 1995: 236, fig. 1029. ��� Huber 2015: 106, 458. TYPE LOCALITY. ��� Not given in original but cited as Mozambique by Heukolom 1866. MATERIAL EXAMINED. ��� Algoa Bay (unlikely) (NHMUK 20170373); Mozambique (USNM 628930); Mozambique (ANSP 234103); Mozambique: Mucoque, near Vilanculos (MNHN). DISTRIBUTION. ��� Mozambique: Mucoque (MNHN), Inhassoro, Mucoque and Bazaruto Island (Kilburn 1974); Madagascar: NW Madagascar (ANSP); Kenya: Ukunda (Huber 2015); Oman: Masirah (Oliver 1995), Muscat (NMW BV6059). HABITAT. ��� No live collected specimens are known. Most records are beach collected and the species is assumed to live subtidally but Huber (2015) records dead shells at 5 m depth in southern Kenya. DESCRIPTION Shell large, L to 80 mm, ovoid, tapering to anterior and posterior, thin shelled, relatively flat T 8.3 mm single valve. Umbones small, low. Posterior dorsal area faintly delineated by shallow sulcus. Sculpture generally smooth with irregular growth lines. Lunule small, narrow, triangular. Ligament short, set in shallow groove. Hinge line thin, RV with two cardinal teeth the posterior bifurcate, anterior tooth smaller, LV with two cardinal teeth, anteriormost bifurcate; lateral teeth absent in both valves. Anterior adductor muscle scar long, narrow, curved, extends ventrally to past mid-line of shell, detached and widely separated from pallial line for nearly all of length. Posterior adductor scar reniform. Pallial line narrow, entire. Pallial blood vessel scar visible, terminating ventrally at lower part of anterior adductor scar. Shell interior with fine radial ridges and sometimes exposed organic layers. Shell outside pallial line glossy, margin smooth. REMARKS Among living Lucinidae Retrolucina voorhoevei n. comb. has an unusual, elongate, laterally compressed shell shape that is only matched by some deep water taxa such as Gloverina and Elliptiolucina (Cosel & Bouchet, 2008) or Jorgenia (Tay - lor & Glover, 2009) but these have short anterior adductor muscle scars and molecular results show they belong in the Myrteinae (Taylor et al. 2014, 2016). By contrast, although details of habitat are lacking, the presence of dead shells on beaches suggests that R. voorhoevei n. comb. is a shallow subtidal species. The Eocene congener, R. defrancei, was also a shallow water species recorded by Courville et al. (2012) from the Paris Basin at Damery (Lutetian), in beds associated with cerithiid and potamidid gastropods., Published as part of Taylor, John D. & Glover, Emily A., 2018, Hanging on - lucinid bivalve survivors from the Paleocene and Eocene in the western Indian Ocean (Bivalvia: Lucinidae), pp. 123-142 in Zoosystema 40 (7) on pages 135-136, DOI: 10.5252/zoosystema2018v40a7, http://zenodo.org/record/3738245, {"references":["DESHAYES G. P. 1857. - Note sur une nouvelle lucine, et description de l'espece. Journal de Conchyliologie 6: 104 - 107.","DANCE S. P. 1986. - A history of shell collecting. E. J. Brill, Leiden. 265 p.","JUTTING W. S. S. VAN B. 1939. - A brief history of the conchological collections at the Zoological Museum of Amsterdam, with some reflections on 18 th century shell cabinets and their proprietors, on the occasion of the centenary of the Royal Zoological Society \" Natura Artis Magistra \". Bijdragen tot de Dierkunde 27: 167 - 246.","CHAVAN A. 1938. - Essai critique de classification des lucines. Journal de Conchyliologie 82 (1): 59 - 97; 82 (2): 105 - 130; 82 (3): 215 - 241.","KILBURN R. N. 1974. - Taxonomic notes on South African marine Mollusca (4) Bivalvia, with descriptions of new species of Lucinidae. Annals of the Natal Museum 22: 335 - 348.","OLIVER P. G. 1995. - Bivalvia, in DANCE S. P. (ed.). Seashells of Eastern Arabia. Motivate Publishing, Dubai: 194 - 281.","HUBER M. 2015. - Compendium of bivalves 2. Harxheim: ConchBooks, 907 p.","HEUKOLOM F. 1866. - Note sur l'identite des Lucina voorhoevei Desh. et L. mirabilis Dunker. Journal de Conchyliologie 14: 39 - 40.","COSEL R. VON & BOUCHET P. 2008. - Tropical deep-water lucinids (Mollusca: Bivalvia) from the Indo-Pacific: essentially unknown, but diverse and occasionally gigantic, in HEROS V., COWIE R. & BOUCHET P. (eds) Tropical Deep Sea Benthos, volume 25. Museum national d'Histoire naturelle, Paris, 806 p. (Memoires du Museum national d'Histoire naturelle; 196): 115 - 213.","TAYLOR J. D., GLOVER E. A. & WILLIAMS S. T. 2014. - Diversification of chemosymbiotic bivalves: origins and relationships of deeper water Lucinidae. Biological Journal of the Linnean Society 111: 401 - 420. https: // doi. org / 10.1111 / bij. 12208","TAYLOR J. D., GLOVER E. A., SMITH L., IKEBE C. & WILIAMS S. T. 2016. - New molecular phylogeny of Lucinidae: increased taxon base with focus on tropical Western Atlantic species (Mollusca: Bivalvia). Zootaxa 4196 (3): 381 - 398. https: // doi. org / 10.11646 / zootaxa. 4196.3.2","COURVILLE P., PACAUD J. - M., MERLE D. & LEBRUN P. 2012. - Le Lutetien de Damery (Marne, France) geologie, environnements, associations de bivalves et gasteropodes. Fossiles, hors-serie III: 57 - 71."]}

Genus Retrolucina n. gen. urn:lsid:zoobank.org:act: DAFC3EBA-0C19-4D63-8248-65A6F761670A TYPE SPECIES. — Lucina voorhoevei Deshayes, 1857. Recent, Western Indian Ocean DIAGNOSIS. — Shell large L to 80 mm, thin-shelled, ovoid, laterally compressed, longer than high, tapering to anterior and posterior. Umbones low. Posterior dorsal area faintly delineated by shallow sulcus. Sculpture generally smooth with growth lines, sometimes with irregular short anterior and posterior marginal folds. Lunule small, narrow, triangular. Hinge line thin, two small bifurcate cardinal teeth in both valves, lateral teeth absent. Anterior adductor muscle scar long, narrow, curved, extends ventrally to past mid-line of shell, detached and widely separated from pallial line for nearly all of length. Pallial line narrow, entire. Shell interior with fine radial ridges. Inner shell margin smooth. ETYMOLOGY. — Latin ‘retro’ – backwards and lucina in reference to similarity of Eocene species to the sole living species. Feminine. DISTRIBUTION. — Western Indian Ocean particularly Mozambique. GEOLOGICAL RANGE. — Lucina defrancei Deshayes, 1857, Eocene, Lutetian, Paris Basin (Fig. 6 I-N) is very similar to R. voorhoevei n. comb. in shape, external sculpture, hinge teeth, and characters of anterior adductor muscle scar. REMARKS Previously included in Eomiltha, R. voorhoevei n. comb. differs from the type species by a number of characters. In shell outline, R. voorhoevei n. comb. tapers posteriorly compared with E. contorta that is posteriorly truncate with a shallow sinus. The shell exterior is smooth compared with the more rugose Eomiltha, the anterior adductor scar is thinner and longer and the cardinal teeth smaller. In Retrolucina n. gen. the pallial line lacks the posterior angle towards the posterior adductor scar of Eomiltha contorta. Although Retrolucina n. gen. and Eomiltha are clearly related such morphological differences within living lucinids would suggest different generic placement. This is demonstrated by the various laterally compressed lucinids (e.g. Gloverina, Taylorina, Dulcina, Elliptiolucina) described from Indonesia and Philippines by Cosel & Bouchet (2008) with several of these later corroborated by molecular analyses (Taylor et al. 2011, 2014, 2016). An Eocene (Lutetian) species usually referred to Eomiltha is Lucina defrancei Deshayes, 1857 (synonym L. cuvieri Bayan, 1870) from the Paris Basin (Figs 6 I-N; 7C, D) it is very similar to Retrolucina voorhoevei n. comb. in shell characters and we regard it as congeneric and an antecedent. Despite an extensive literature and collection search we failed to find any species resembling R. defrancei and R. voorhoevei n. comb. recorded from deposits between the Eocene and present day. Further back in geological time we previously (Taylor & Glover 2000, 2006) compared Illiona prisca (Hisinger, 1837) from the Silurian of Gotland, Sweden with R. voorhoevei n. comb., it has a similar flat-shelled, elongate-ovate shape and internally has a very long anterior adductor muscle scar that extends posteriorly to the midline of the shell. The resemblance in shape is remarkable but, in the absence of any fossil record of similar forms from the later Palaeozoic through the Mesozoic, likely results from morphological convergence rather than phylogenetic continuity.

Genus Gibbolucina Cossmann, 1904 Phacoides (Gibbolucina) Cossmann in Cossmann & Peyrot, 1904: 13. TYPE SPECIES. ��� Venus callosa Lamarck, 1806: Eocene, Lutetian (original designation). DIAGNOSIS. ��� Shell small L to 15 mm, subtrigonal, ventrally round- ed, umbones prominent. Shallow sulcus defining posterior dorsal area in most species. Lunule inset, long. Sculpture of irregular low commarginal lamellae. Hinge with two cardinal teeth in left valve and single, often bifid, cardinal in right valve, lateral teeth absent. Ligament short, in shallow resilifer. Anterior adductor muscle scar short, narrow, detached for half to 2/3 of length, pallial line entire, inner shell margin smooth, interior often thickened, with pallial blood vessel scar in deep groove. GEOLOGICAL RANGE. ��� Eocene (Lutetian) to Recent. The fossil record of Gibbolucina species extends from the early Eocene to the Miocene. INCLUDED SPECIES. ��� Eocene. Lutetian: Gibbolucina callosa (Lamarck, 1806) (Fig. 1A-G) and G. gibbosula (Lamarck, 1806). Bartonian. Gibbolucina lefevrei (Cossmann, 1887) (Fig. 1J, K), G. axinoides (Dufour, 1881) (Fig. 1H, I), G. profunda (Dufour, 1881). Priabonian (Ludien). Gibbolucina incomposita (von Koenen, 1893) see Pacaud & Ledon 2007). Miocene Aquitanian. Gibbolucina avitensis (Cossmann & Peyrot, 1912) (1912: 271-273, pl. 27, figs 14-17). Saint Avit, Landes, Aquitaine (MNHN.F.06430). Burdigalian. Gibbolucina trigonula (Deshayes, 1830) Moulin de Gamachot, Aquitaine (Cossmann & Peyrot 1912: pl. 26, figs 70- 73) (Fig. 1L-P). Pliocene. A Late Pliocene-early Pleistocene species, Gibbolucina salebrosa (Woods, 1931), was described from southwestern Australia (see Ludbrook 1978: pl. 3, figs 6-9) but this lacks hinge teeth, and the deeply scooped lunule of Gibbolucina and also has widely spaced prominent commarginal lamellae. We regard this species as distinct from Gibbolucina but in a broadly related genus (undescribed). Another Pliocene species, Gibbolucina confirmans (Ludbrook, 1955), was described from two incomplete shells from a borehole near Adelaide, South Australia but the generic assignment is doubtful. Recent. Gibbolucina zelee n. sp. COMPARISON WITH OTHER GENERA Despite Chavan (1969) and others including Eomiltha as a subgenus of Gibbolucina or, alternatively, Gibbolucina as a subgenus of Eomiltha (Ludbrook 1955), there is little similarity of shell characters (see below) and any relation- ship is highly unlikely. In contrast, several described genera have similar characters to Gibbolucina and are likely broadly related. These are Megaxinus (type species Lucina transversa Bronn, 1831), Rasta Taylor & Glover, 2000 (type species Rastafaria thiophila Taylor & Glover, 1997 [Taylor & Glover 1997, 2000]), and Parvidontia Glover & Taylor, 2007 (type species P. laevis Glover & Taylor, 2007). To date, only Rasta lamyi has been included in molecular analyses (Taylor et al. 2011, 2016) where it groups in the subfamily Lucininae. Megaxinus species are often similar in shape to Gibbolucina but all lack hinge teeth, although there are sometimes irregular folds on the hinge plate. They also exhibit ontogenetic changes in shape, becoming relatively higher and thicker shelled with age (Glover & Taylor 1997; Cosel & Bouchet 2008). Furthermore, the anterior adductor muscle scar is longer and detached from pallial line for about 2/3 of length rather than about half of length in most Gibbolucina species. Rasta species also similarly lack hinge teeth but have a subtrigonal shape, higher than long, with prominent umbones and the two known species, R. thiophila and R. lamyi, possess in live or fresh shells, distinctive, long periostracal extensions (Glover & Taylor 1997; Taylor & Glover 1997; Taylor et al. 2005). An earlier Rasta- like species is Megaxinus ellipticus var. trigona Sacco, 1901 described from the early Pliocene of northern Italy (MRSN BS154.02.006) and which has a similar higher than long shape, with sharp, curved umbones. Another similar genus, Parvidontia, was introduced (Glover & Taylor 2007) based on P. laevis from New Caledonia, a small species with sub-circular, thin shells and small cardinal teeth. Subsequently, Glover & Taylor (2016) concluded that the P. laevis specimens were likely juvenile shells and described a second species, P. mutabilis Glover & Taylor, 2016, from the Philippines that, in larger individuals, has the general shell form of Megaxinus but with small cardinal teeth. Parvidontia is similar to Gibbolucina in shape but has a very thin hinge plate, a sculpture of fine commarginal lamellae and lacks a thick periostracum., Published as part of Taylor, John D. & Glover, Emily A., 2018, Hanging on - lucinid bivalve survivors from the Paleocene and Eocene in the western Indian Ocean (Bivalvia: Lucinidae), pp. 123-142 in Zoosystema 40 (7) on pages 125-127, DOI: 10.5252/zoosystema2018v40a7, http://zenodo.org/record/3738245, {"references":["COSSMANN M. 1904. - Mollusques eoceniques de la Loire-Inferieure. Tome III, fasc. 1. Bulletin de la Societe des Sciences naturelles de l'Ouest de la France, 2 e ser. 4: 149 - 213.","LAMARCK J. B. 1806. - Memoires sur les fossils des environs de Paris (suite 6). Annales du Museum d'Histoire naturelle 7: 130 - 139.","PACAUD J. - M. & LEDON D. 2007. - Sur les especes de mollusques du Ludien (Priabonien, Eocene superieur) du bassin de Paris introduites par Perier en 1941. Cossmanniana 11: 7 - 25.","COSSMANN M. & PEYROT A. 1912. - Conchologie neogenique de l'Aquitaine. Actes de la Societe linneenne de Bordeaux 65 (4): 179 - 333.","LUDBROOK N. H. 1978. - Quaternary molluscs of the western part of the Eucla Basin. Bulletin Geological Survey of Western Australia 125: 5 - 286.","LUDBROOK N. H. 1955. - The molluscan fauna of the Pliocene strata underlying the Adelaide Plains. Part II - Pelecypoda. Transactions of the Royal Society of South Australia 78: 18 - 87.","CHAVAN A. 1969. - Superfamily Lucinacea Fleming, 1828, in MOORE R. C. (ed.), Treatise on Invertebrate Paleontology, Part N, Mollusca 6, Bivalvia, volume 2., Geological Society of America and University of Kansas, Boulder, Colorado: N 491 - N 518.","TAYLOR J. D. & GLOVER E. A. 2000. - Nomenclatural rectifications for Indo-Pacific Lucinidae. Journal of Conchology 37: 82.","GLOVER E. A. & TAYLOR J. D. 1997. - New species and records of Rastafaria and Megaxinus (Bivalvia: Lucinidae) from the Western Indian Ocean and Red Sea, with a reappraisal of Megaxinus. Journal of Conchology 36: 1 - 18.","GLOVER E. A. & TAYLOR J. D. 2007. - Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou. Zoosystema 29 (1): 109 - 181.","TAYLOR J. D., GLOVER E. A., SMITH L., DYAL P. & WILLIAMS S. T. 2011. - Molecular phylogeny and classification of the chemosymbiotic bivalve family Lucinidae (Mollusca: Bivalvia). Zoological Journal of the Linnean Society 163: 15 - 49. https: // doi. org / 10.1111 / j. 1096 - 3642.2011.00700. x","TAYLOR J. D., GLOVER E. A., SMITH L., IKEBE C. & WILIAMS S. T. 2016. - New molecular phylogeny of Lucinidae: increased taxon base with focus on tropical Western Atlantic species (Mollusca: Bivalvia). Zootaxa 4196 (3): 381 - 398. https: // doi. org / 10.11646 / zootaxa. 4196.3.2","TAYLOR J. D. & GLOVER E. A. 1997. - A chemosymbiotic lucinid bivalve (Bivalvia: Lucinoidea) with periostracal pipes; functional morphology and description of a new genus and species, in WELLS F. E. (ed.), The Marine Flora and Fauna of the Houtman Abrolhos Islands, Western Australia. Western Australian Museum: 335 - 361.","COSEL R. VON & BOUCHET P. 2008. - Tropical deep-water lucinids (Mollusca: Bivalvia) from the Indo-Pacific: essentially unknown, but diverse and occasionally gigantic, in HEROS V., COWIE R. & BOUCHET P. (eds) Tropical Deep Sea Benthos, volume 25. Museum national d'Histoire naturelle, Paris, 806 p. (Memoires du Museum national d'Histoire naturelle; 196): 115 - 213.","TAYLOR J. D. & GLOVER E. A. 2005. - Cryptic diversity of chemosymbiotic bivalves: a systematic revision of worldwide Anodontia (Mollusca: Bivalvia: Lucinidae). Systematics and Biodiversity 3: 281 - 338. https: // doi. org / 10.1017 / S 1477200005001672","SACCO F. 1901. - I molluschi dei terreni terziarii del Piemonte e della Liguria. Parte 29, Clausen Torino, 216 p.","GLOVER E. A. & TAYLOR J. D. 2016. - Lucinidae of the Philippines: highest known diversity and ubiquity of chemosymbiotic bivalves from intertidal to bathyal depths (Mollusca: Bivalvia). in HEROS V., STRONG E. & BOUCHET P. (eds), Tropical Deep- Sea Benthos 29. Museum national d'Histoire naturelle, Paris, 463 p. (Memoires du Museum national d'Histoire naturelle; 208): 65 - 234."]}

Superfamily THYASIROIDEA Dall, 1900 Family THYASIRIDAE Dall, 1900

Superfamily THYASIROIDEA Dall, 1900 Family THYASIRIDAE Dall, 1900, Published as part of Oliver, P. Graham, 2015, Deep-water Thyasiridae (Mollusca: Bivalvia) from the Oman Margin, Arabian Sea, new species and examples of endemism and cosmopolitanism, pp. 252-263 in Zootaxa 3995 (1) on page 253, DOI: 10.11646/zootaxa.3995.1.21, http://zenodo.org/record/236857

Oliver, P. Graham (2015): Deep-water Thyasiridae (Mollusca: Bivalvia) from the Oman Margin, Arabian Sea, new species and examples of endemism and cosmopolitanism. Zootaxa 3995 (1): 252-263, DOI: http://dx.doi.org/10.11646/zootaxa.3995.1.21

Rare species of three long-lived lucinid genera, Gibbolucina Cossmann, 1904, Barbierella Chavan, 1938 and Retrolucina n. gen., with origins in the Paleocene and Eocene of western Tethys, are present in the Mozambique Channel area of the southwestern Indian Ocean but absent elsewhere in the Indo-West Pacific. A new species, Gibbolucina zelee n. sp., is described from the Banc de la Zélée and western Madagascar that resembles Miocene species from western France. Since their origin in the Paleocene to the present day Barbierella species have always been rare. New records and images, including syntypes, are provided for Barbierella louisensis (Viader, 1951) from Mauritius and the Mozambique Channel, with Barbierella scitula Oliver & Abou-Zeid, 1986 from the Red Sea regarded as synonym. A new genus, Retrolucina n. gen., is proposed with the living Lucina voorhoevei Deshayes, 1857 (usually called Eomiltha voorhoevei) as type species and also including Lucina defrancei Deshayes, 1857, a strikingly similar species from the Eocene of the Paris Basin. Retrolucina n. gen. differs from Eomiltha Cossmann, 1912 in shape, sculpture and hinge characters. Monitilora Iredale, 1930, another genus of Paleocene or earlier origins, includes a few living species in the Indo-West Pacific and is now identified from Mozambique with Monitilora sepes (Barnard, 1964) (formerly Phacoides sepes Barnard, 1964). It is suggested that Gibbolucina, Barbierella and Retrolucina n. gen. species became isolated in the western Indian Ocean following the closure of the Tethyan Seaway in the early Miocene while their congeners in western Tethys became extinct. The survival of these rare genera, with restricted geographical ranges and seemingly small populations, runs counter to current ideas concerning long-term extinction risk., Des espèces rares appartenant à trois genres anciens de lucines, Gibbolucina Cossmann, 1904, Barbierella Chavan, 1938 et Retrolucina n. gen., dont l'origine se situe au Paléocène et à l'Éocène en Téthys occidentale, sont présentes dans la zone du Canal du Mozambique dans le sud-ouest de l'océan Indien, et absentes ailleurs dans l'Indo-Ouest Pacifique. Une nouvelle espèce, Gibbolucina zelee n. sp., est décrite du Banc de la Zélée et de l'ouest de Madagascar; elle ressemble à une espèce du Miocène de l'ouest de la France. Depuis leur origine au Paléocène jusqu'à nos jours, les espèces de Barbierella ont toujours été rares. Des signalisations nouvelles et des illustrations, dont celles de syntypes, sont données pour Barbierella louisensis (Viader, 1951) de l'île Maurice et du Canal du Mozambique, et Barbierella scitula Oliver & Abou-Zeid, 1986 de la Mer Rouge est donnée comme synonyme. Le nouveau genre Retrolucina n. gen. est établi avec pour espèce type l'espèce actuelle Lucina voorhoevei Deshayes, 1857 (habituellement appelée Eomiltha voorhoevei), et comprenant également Lucina defrancei Deshayes, 1857, une espèce de l'Éocène du Bassin Parisien qui lui est étonnamment semblable. Retrolucina n. gen. diffère d'Eomiltha Cossmann, 1912 par sa forme, sa sculpture et les caractères de sa charnière. Monitilora sepes (Barnard, 1964), du Mozambique (auparavant Phacoides sepes Barnard, 1964), est classée dans le genre Monitilora Iredale, 1930, un autre genre dont l'origine remonte au moins au Paléocène et qui comprend un petit nombre d'espèces actuelles de l'Indo-Ouest Pacifique. Les espèces de Gibbolucina, Barbierella et Retrolucina n. gen. ont pu se retrouver isolées dans l'Ouest de l'océan Indien à la suite de la fermeture de la Téthys au début du Miocène alors que leurs congénères de la Téthys occidentale se sont éteintes. La survie de ces genres rares, avec des aires de distribution restreintes et apparemment de petites populations, va à l'encontre des idées classiques sur les risques d'extinction à long terme.

Oliver, P. Graham, Frey, Melissa A. (2014): Ascetoaxinus quatsinoensis sp. et gen. nov. (Bivalvia: Thyasiroidea) from Vancouver Island, with notes on Conchocele Gabb, 1866, and Channelaxinus Valentich-Scott & Coan, 2012. Zootaxa 3869 (4): 452-468, DOI: http://dx.doi.org/10.11646/zootaxa.3869.4.8

Ascetoaxinus gen. nov. Type species. Ascetoaxinus quatsinoensis sp. nov., this paper. Type locality. Quatsino Sound, off of Vancouver Island, British Columbia, Canada; 50��15.482���N, 128��26.400���W to 50��14.519���N, 128��26.567���W; 1086���1318m. Species included. Ascetoaxinus quatsinoensis sp. nov.; Ascetoaxinus ovoidea (Dall, 1890). Diagnosis. Medium sized shells. Equivalve. Inequilateral, prosogyrous beaks close to the anterior, outline obliquely oval. Anterior margin sloping steeply, almost straight; anterior area defined by a distinct keel, with a deeply impressed lunule encompassing the entire anterior area. Lunule edge scalloped by rounded projections. Posterior margin broadly rounded, indented by a single sinus; posterior sulcus large, deep, distinctly angulated; submarginal sulcus smaller, sharply defining escutcheon but no distinct marginal sinus. Weak angulation between umbo and posterior ventral margin resulting in flattened area adjacent to the posterior sulcus. Anterior adductor muscle scar greatly elongate. Hinge teeth lacking. Ligament partially sunken. Gill anatomy of Dufour type 3 (Dufour 2005), filaments laminar, frontal surface broad, flat with marginal arrays of cilia. Lateral body pouches large, dense arborescent, dorsal extension of digestive gland prominent with external outgrowths. Etymology. From the Greek asketos meaning curiously fashioned and pertaining to the unusual scalloped lunule and the Greek axinus meaning like an axe, but also pertaining to the thyasirid genus Axinus; gender feminine (Brown 1956)., Published as part of Oliver, P. Graham & Frey, Melissa A., 2014, Ascetoaxinus quatsinoensis sp. et gen. nov. (Bivalvia: Thyasiroidea) from Vancouver Island, with notes on Conchocele Gabb, 1866, and Channelaxinus Valentich-Scott & Coan, 2012, pp. 452-468 in Zootaxa 3869 (4) on page 455, DOI: 10.11646/zootaxa.3869.4.8, http://zenodo.org/record/4947378, {"references":["Dall, W. H. (1890) Scientific results of the explorations by the U. S. Fish Commission Steamer \" Albatross \". VII. Preliminary report on the collections of Mollusca and Brachiopoda obtained in 1887 - 1888. Proceedings of the United States National Museum, 12, 219 - 362.","Dufour, S. C. (2005) Gill anatomy and evolution of symbiosis in the bivalve family Thyasiridae. Biological Bulletin, 208, 200 - 212. http: // dx. doi. org / 10.2307 / 3593152","Brown, R. W. (1956) Composition of Scientific Words. Smithsonian Institution Press, London and Washington, 882 pp."]}

Ascetoaxinus quatsinoensis sp. nov. Figs. 2���6 Type material. Holotype, single specimen, off Quatsino Sound, Vancouver Island, British Columbia, Canada, 50��15.482��N, 128��26.400��W to 50��14.519��N, 128��26.567��W, 1086���1318m. Coll. J. Boutillier, Fisheries and Oceans Canada, 02 September 2004. RBCM 010-00221 - 005. Measurements. Description. Shell (Fig. 2). 31.3mm in length. Thin, brittle. Equivalve. Moderately tumid. Strongly inequilateral, prosogyrous beaks close to the anterior margin. Outline obliquely oval; anterior margin almost straight bounding a large excavated lunule; ventral margin long, almost straight; posterior margin broad, sulcate with a distinct posterior dorsal sinus. Posterior sulcus sharply defined, relatively narrow; submarginal sulcus sharply defining a flattened escutcheon. Posterior ventral slope anterior of the posterior sulcus a little flattened, creating a weak secondary ridge. Hinge teeth lacking, ligament partially sunken, relatively short being less than half the length of the escutcheon. Sculpture of well-defined growth lines; edge of lunule drawn out into five rounded projections. Muscle scars indistinct; anterior adductor scar elongate and parallel with ventral margin. Shell colour white. Anatomy (Figs. 3���6). Mantle is thin; unfused except for the formation of a small exhalant aperture (Fig. 3, ex). Anterior adductor scar elongate and approximately 4 times longer than posterior adductor scar; free from mantle edge for about one-fifth of its ventral edge; posterior adductor muscle oval. Foot vermiform (Fig. 3), very long, tip not noticeably expanded, heel obsolete, protractor muscles very slender. Labial palps small, narrow with a distinctly grooved dorsal zone and a long tubular portion leading to the mouth (Fig. 5A, B). Alimentary system (Fig. 4) with short oesophagus leading to a relatively small stomach; large digestive ducts leading to the lateral body pouches open into the ventral anterior face (Fig. 5D, dd, np), smaller ducts open dorsally on the left side and lead to a pair of outgrowths (Fig. 5B, dg); walls of the combined style sac and mid gut thickened (Fig. 5D, ss/mg), remainder of mid gut coiling back over style sac, passing through heart and coiling towards the posterior as the hind gut; anus opening into exhalant aperture (Fig. 4). Lateral body pouches large, arborescent, terminations cloven or single, blunt (Fig. 5C). Kidney large and packed with golden coloured granules. Ctenidium large, both demibranchs with fully reflected filaments; outer demibranch about half the depth of the inner demibranch (Fig. 3, od, id). Filaments laminar (Fig. 6A, C), frontal zone narrow, abfrontal zone extended and fused across the ascending and descending arms, creating junctions between the ascending and descending lamellae (Fig. 6A, abs). Ventrally every filament is fused. The frontal surface (Fig. 6B) is ciliated with distinct lateral cilia (lc) and laterofrontal cirri (lfc); frontal cilia not apparent, instead adjacent frontal zone appears wide and smooth (sfz). Abfrontal surfaces lined with bacteriocytes that are domed and roundly polygonal with a glycocalyx (Fig. 6C, bc). Bacilli bacteria also present in defined bundles, measuring 1.1 um in length (Fig. 6D, bct)., Published as part of Oliver, P. Graham & Frey, Melissa A., 2014, Ascetoaxinus quatsinoensis sp. et gen. nov. (Bivalvia: Thyasiroidea) from Vancouver Island, with notes on Conchocele Gabb, 1866, and Channelaxinus Valentich-Scott & Coan, 2012, pp. 452-468 in Zootaxa 3869 (4) on pages 455-456, DOI: 10.11646/zootaxa.3869.4.8, http://zenodo.org/record/4947378

Ascetoaxinus ovoidea (Dall, 1890) Fig. 7 Type material. Holotype, single specimen, 87 miles off Cape Fear, North Carolina, United States, 646m. Coll. United States Fish Commission. USNM 64226. Synonymy. Cryptodon ovoideus, Dall, 1890; Thyasira ovoidea (Dall, 1890). Measurements. Description. Shell (Fig. 7). 25mm in length. Brittle, chalky. Equivalve. Moderately tumid. Strongly inequilateral, prosogyrous beaks close to the anterior margin. Outline obliquely oval; anterior margin almost straight bounding a large excavated lunule; ventral margin long, almost straight; posterior margin broad, sulcate with a distinct posterior dorsal sinus and faint submarginal sulcus. Posterior sulcus sharply defined, relatively narrow; submarginal sulcus sharply defining a projecting escutcheon. Posterior ventral slope anterior of the posterior sulcus a little flattened, creating a weak secondary ridge. Hinge teeth lacking; ligament partially sunken, relatively short with length less than half that of escutcheon. Sculpture of well-defined growth lines; edge of lunule drawn out into two rounded projections. Muscle scars prominent; anterior adductor scar elongate, mostly separate from pallial line, and in parallel with ventral margin. Shell colour, creamy-white. Remarks. Based on putative geographic distributions coupled with obvious biogeographic barriers, it is most unlikely that Ascetoaxinus quatsinoensis is conspecific with A. ovoidea. Panamic and Caribbean geminate taxa in the Arcoidea have been shown to be distinct species (Marko and Moran, 2009) and this probably applies to most bivalves. Shell morphology differences are present; in A. quatsinoensis the scalloping of the lunule is more prominent as is the definition of the escutcheon., Published as part of Oliver, P. Graham & Frey, Melissa A., 2014, Ascetoaxinus quatsinoensis sp. et gen. nov. (Bivalvia: Thyasiroidea) from Vancouver Island, with notes on Conchocele Gabb, 1866, and Channelaxinus Valentich-Scott & Coan, 2012, pp. 452-468 in Zootaxa 3869 (4) on page 457, DOI: 10.11646/zootaxa.3869.4.8, http://zenodo.org/record/4947378, {"references":["Dall, W. H. (1890) Scientific results of the explorations by the U. S. Fish Commission Steamer \" Albatross \". VII. Preliminary report on the collections of Mollusca and Brachiopoda obtained in 1887 - 1888. Proceedings of the United States National Museum, 12, 219 - 362.","Marko, P. B. & Moran, A. L. (2009) Out of sight, out of mind: high cryptic diversity obscures the identities and histories of geminate species in the marine bivalve subgenus Acar. Journal of Biogeography, 36, 1861 - 1880. http: // dx. doi. org / 10.1111 / j. 1365 - 2699.2009.02114. x"]}

Hryniewicz, Krzysztof, Little, Crispin T.S., Nakrem, Hans Arne (2014): Bivalves from the latest Jurassic-earliest Cretaceous hydrocarbon seep carbonates from central Spitsbergen, Svalbard. Zootaxa 3859 (1): 1-66, DOI: http://dx.doi.org/10.11646/zootaxa.3859.1.1

Genus Cretaxinus gen. nov. Type species. Cretaxinus hurumi sp. nov. Etymology. Refers to the Cretaceous occurrence of the type species, and to the genus Axinus. Diagnosis. Shell inequilateral, triangular in outline, thin. Ornament of commarginal growth lines. Beaks weakly prosogyrate, not very prominent. Cardinal area edentulous, with small ligament groove. No lateral teeth. Lunule long and deep. Posterior sulcus shallow, posterior fold not very prominent. Submarginal sulcus shallow; no auricle. Ligament short, thick, external, with possible small internal portion. Anterior adductor muscle scar elongated, very weak; size difficult to estimate, but relatively small. Posterior adductor muscle scar larger than anterior one, circular, well impressed. Pallial line entire. Remarks. Comparison of Cretaxinus gen. nov. with other large, chemosymbiotic thyasirids (Dufour 2005) suggest it can be clearly differentiated from all of them (Tab. 2). The most noticeable feature is its subtriangular shape, which is very distinct from the shapes of the genera Axinus J. Sowerby, 1821, Thyasira Lamarck, 1818, Parathyasira Iredale, 1930, and Conchocele Gabb, 1866 (Tab. 2). Another feature distinguishing Cretaxinus from other thyasirids is its short, thick and external ligament set in a deep escutcheon, accompanied by a possible small internal portion. A similar feature is seen only in Axinus. However, Axinus has a totally different shape, sulci, adductor muscle proportions and external ornament (Tab. 2). The ligament of Cretaxinus is very distinct from that of Thyasira, Parathyasira and Conchocele, all of which have variably long, sunken ligaments (Tab. 2). Another major difference between Cretaxinus and Axinus, Thyasira, Parathyasira and Conchocele is the proportions of adductor muscle scars. In Cretaxinus the anterior adductor muscle scar is small and weak, and the posterior adductor muscle scar is large and well impressed; in the other genera the proportions of the muscle scars are reversed. The sulci are less distinct and somehow anteroposteriorly flattened in comparison to the sulci of the other discussed genera. The escutcheon is wider and deeper than that of Thyasira and Parathyasira. Knowledge of small thyasirid species is far less complete than of their large relatives (Payne & Allen 1991; Oliver & Killeen 2002) and therefore their direct comparison with Cretaxinus gen. nov. is more problematic. Mendicula Iredale, 1924, has a very small, oval shell (Cretaxinus gen. nov. Both sulci of Mendicula are shallow and the ligament is entirely internal (Zelaya 2010), also unlike in Cretaxinus gen. nov., which has weak sulci but largely external ligament. Adontorhina Berry, 1947, apart from small, oval shells with an internal ligament, differs from Cretaxinus by characteristic granules on the hinge plate of the former (Scott 1986; Barry & McCormick 2007). Axinulus Verrill & Bush, 1898, has a small oval shell which is higher than long (Payne & Allen 1991) and a largely internal ligament, also unlike Cretaxinus gen. nov. The current lack of taxonomically robust characters in the shells of the Thyasiridae leads to problems of generic separation within the family (e.g. Payne & Allen 1991; Oliver & Killeen 2002; Oliver & Sellanes 2005; Oliver & Holmes 2006; Rodrigues et al. 2008). Molecular data suggest that current thyasirid generic definitions might be inadequate and additional morphological studies may result in redefinition of the genera (Taylor et al. 2007). Further, the same data show only a weak separation between larger, chemosymbiotic thyasirids and small (Mendicula Iredale, 1924, Leptaxinus Verrill & Bush, 1898, Adontorhina Berry, 1947, and Axinulus Verrill & Bush, 1898 (Dufour 2005).

Cretaxinus hurumi sp. nov. (Figures 13 K–N, 15, 16 A–G) 2011 Thyasira sp. —Hammer et al., fig. 7a–c, tab. 2. Etymology. After Jørn H. Hurum, leader of 2004–2012 Svalbard expeditions of the Natural History Museum, University of Oslo. Type locality. Seep 9, Knorringfjellet, Spitsbergen, 78°18’49.9”N 16°10’58.9”E. Type mterial. Holotype: PMO 217.277; an internal mould with shell partially preserved, showing a triangular outline, external ornament, a sulcated posterior margin and a thick, short, external ligament. Paratypes: PMO 217.172; an almost complete internal mould showing outline and anterior adductor muscle scar. PMO 217.175; a fragment of an internal mould and silicone rubber cast showing posterior adductor muscle scar and posterior pedal retractor. The silicone rubber cast shows the cardinal area with an elongated resilifer. PMO 217.540; complete internal mould showing the triangular outline, well impressed rounded posterior adductor muscle scar and deep escutcheon. PMO 225.128; an almost complete internal mould showing anterior adductor muscle scar and crosssection through the external ligament and ligament nymphs. PMO 225.136; an internal mould showing very weak anterior adductor muscle scar. Material examined. 56 specimens, all articulated or semi-articulated internal moulds with variable amounts of shell preserved. See Appendix 1 for list of specimens. Dimensions. 23–56.5 mm in length, 12.6–50 mm in height, 19–39 mm in width. See Figure 17 A–D and Appendix 2K for details. Diagnosis. As for the genus. Description. Shell large, subtriangular in outline, up to 56.5 mm long, 50 mm high, and 39 mm wide. Average H/L ratio ≈ 0.85, W/L ≈ 0.75, and W/H ≈ 0.88. Shell less than 0.5 mm thick, covered with commarginal growth lines. Umbonal angle usually larger among smaller specimens, which have concave anterodorsal and posterodorsal margins. Beaks incurved, prosogyrate, not prominent, positioned closer towards the anterior, with average Pl/L ≈ 0.67. Umbonal angle slightly acute. Lunule large, deep, heart-shaped. Anterior margin tightly rounded, more angular in larger specimens. Ventral margin curved, with curvature deepest close to mid-line in smaller specimens, progressively displaced towards posterior during growth. Curvature shows some intraspecific variation, from deep and prominent, to shallow and gentle. Posterior extremity weakly pointed, posterodorsal margin sloping, with very weak sulcus. Smaller specimens usually have slightly concave posterodorsal margin, which is more straight in larger specimens. Escutcheon large and deep. Ligament external, thick, short, occupying 1/3 of escutcheon. Hinge plate narrow. Cardinal area with single, elongate groove, probably representing a ligament groove. Lateral dentition not observed. Anterior adductor muscle scar very weak and small, elongated along pallial line, with straight ventral margin and irregular dorsal margin; well impressed in anterior part, fading towards posterior so length of anterior adductor muscle scar cannot be fully ascertained. Anterior pedal retractor scar small and weak, circular, separated from the anterior adductor muscle scar by narrow margin, visible in one specimen only. Posterior adductor muscle scar larger than anterior adductor muscle scar, circular, deeply impressed, displaced towards hinge plate. Posterior pedal retractor small, circular, approximately same size as anterior pedal retractor scar; positioned close to hinge plate and separated from posterior adductor muscle scar by narrow distance. Pallial line entire, weak, marked by pallial muscle scars in some specimens. Internal shell surface covered with fine radial ornament, probably representing traces of descending pallial muscles. Remarks. Cretaxinus hurumi gen. et sp. nov. is the oldest thyasirid species known to date. The slightly younger Valanginian to Hauterivian thyasirid is Lucina ? rouyana d’Orbigny, 1844, from the shelf deposits of Europe and possible seep sites of Grodziszcze beds in the Carpathians (Ascher 1906, p. 164, pl. XIV, fig. 9a–c; Kiel et al. 2008a; Kaim et al. 2013), which has more of a typical Thyasira shape. The Albian Lucina ? sculpta Phillips, 1829, from Southern England (Woods 1907, p. 153, pl. 24, fig. 7–9) has a very distinct shape reminiscent of the genus Axinus Sowerby, 1821 (Taylor et al. 2007). Thyasira tanabei Kiel, Amano & Jenkins, 2008 (a) is known from Albian to Campanian hydrocarbon seeps of Hokkaido, Japan. Thyasira tanabei has a large anterior adductor muscle scar, unlike C. hurumi, but the lack of information about the ligament of T. tanabei makes more detailed comparison difficult. Thyasira sp. from the Cenomanian Kanajirasawa seep of Hokkaido (Kiel et al. 2008a) is known from a single, partially preserved specimen only and, therefore, is also difficult to compare to C. hurumi. Various Campanian thyasirid species from the Western Interior Seaway (Kauffman 1967) differ in shape from C. hurumi, having flattened posterior areas, narrow escutcheons, deeper sulci and more ovate shapes, reminiscent of Recent Thyasira species. Occurrence. Seep 9 (uppermost Ryazanian), Slottsmøya Member, Svalbard (Tab. 1). Known only from the type locality. Palaeoecology. We infer that Cretaxinus hurumi was a chemosymbiotic and possibly seep-restricted Mesozoic thyasirid. This is supported by the large shell size of C. hurumi. Among modern thyasirids chemosymbiosis is present mainly in species with two gill demibranchs (Dufour 2005) and these usually have large shells, up to around 10 mm for the genera Axinus, Thyasira and Parathyasira, but can reach up to 110 mm in Conchocele (e.g. Payne & Allen 1991; Kamenev et al. 2001; Oliver & Killeen 2002). Large shells provide enough space in the mantle cavity for large symbiont-bearing gills (Taylor & Glover 2010). In contrast, thyasirids with a single gill demibranch are usually asymbiotic (Dufour 2005; Taylor & Glover 2010). These asymbiotic species are much smaller, with sizes of only a few millimeters (Payne & Allen 1991; Oliver & Levin 2006). Cretaxinus hurumi shells are up to 56.5 mm long, and this is very large for the family, which strongly suggests the species had hypertrophied gills suitable for symbiosis with chemoautotrophic bacteria. Smaller chemosymbiotic thyasirids (≈ 10 mm in length) are known from seep environments (e.g. Dando et al. 2004), but also occur in non-seep settings with high redox potential, such as organic-rich sediments in fjords (Dando & Spiro 1993), pulpmill effluents (Dando & Southward 1986) and in the vicinity of offshore hydrocarbon production sites (Oliver & Killeen 2002). However, the only Recent thyasirid genus which attains sizes comparable to C. hurumi is Conchocele, and this is closely associated with seeps (Kamenev et. al 2001; Okutani 2002; cf. Weaver 1942; Coan et al. 2000). Another line of evidence indicating that C. hurumi was both chemosymbiotic and seep-restricted comes from absence of the species in contemporary ‘normal’ marine sediments on Svalbard (e.g. Sokolov & Bodylevsky 1931; Weir 1933; Birkenmajer et al. 1982), despite being relatively abundant in the hydrocarbon seeps (Hammer et al. 2011). Thyasirids are burrowers (e.g. Dando & Southward 1986; Oliver & Killeen 2002). Chemosymbiotic species dig into fine grained sediment to a depth a few times the length of the shell (Pearson 1972). In these burrows they use a vermiform foot to construct a three dimensional network of downward directed tunnels reaching up to 30 times the length of the shell, which serve as conduits for sulfide-rich pore waters from deeper interstitial levels (Dando & Southward 1986; Zuschin et al. 2001; Oliver & Killeen 2002; Dando et al. 2004; Taylor & Glover 2010). However, they are usually unable to tolerate high sulfide concentrations. Chemosymbiotic thyasirids are also capable of feeding on photosynthetic organic matter if conditions for chemosynthesis become unfavourable (Dando & Spiro 1993). Cretaxinus hurumi was probably a relatively deep burrower, based on similar lines of evidence to the lucinid Tehamatea rasmusseni. Order Venerida Gray, 1854

Genus Cretaxinus gen. nov. Type species. Cretaxinus hurumi sp. nov. Etymology. Refers to the Cretaceous occurrence of the type species, and to the genus Axinus. Diagnosis. Shell inequilateral, triangular in outline, thin. Ornament of commarginal growth lines. Beaks weakly prosogyrate, not very prominent. Cardinal area edentulous, with small ligament groove. No lateral teeth. Lunule long and deep. Posterior sulcus shallow, posterior fold not very prominent. Submarginal sulcus shallow; no auricle. Ligament short, thick, external, with possible small internal portion. Anterior adductor muscle scar elongated, very weak; size difficult to estimate, but relatively small. Posterior adductor muscle scar larger than anterior one, circular, well impressed. Pallial line entire. Remarks. Comparison of Cretaxinus gen. nov. with other large, chemosymbiotic thyasirids (Dufour 2005) suggest it can be clearly differentiated from all of them (Tab. 2). The most noticeable feature is its subtriangular shape, which is very distinct from the shapes of the genera Axinus J. Sowerby, 1821, Thyasira Lamarck, 1818, Parathyasira Iredale, 1930, and Conchocele Gabb, 1866 (Tab. 2). Another feature distinguishing Cretaxinus from other thyasirids is its short, thick and external ligament set in a deep escutcheon, accompanied by a possible small internal portion. A similar feature is seen only in Axinus. However, Axinus has a totally different shape, sulci, adductor muscle proportions and external ornament (Tab. 2). The ligament of Cretaxinus is very distinct from that of Thyasira, Parathyasira and Conchocele, all of which have variably long, sunken ligaments (Tab. 2). Another major difference between Cretaxinus and Axinus, Thyasira, Parathyasira and Conchocele is the proportions of adductor muscle scars. In Cretaxinus the anterior adductor muscle scar is small and weak, and the posterior adductor muscle scar is large and well impressed; in the other genera the proportions of the muscle scars are reversed. The sulci are less distinct and somehow anteroposteriorly flattened in comparison to the sulci of the other discussed genera. The escutcheon is wider and deeper than that of Thyasira and Parathyasira. Knowledge of small thyasirid species is far less complete than of their large relatives (Payne & Allen 1991; Oliver & Killeen 2002) and therefore their direct comparison with Cretaxinus gen. nov. is more problematic. Mendicula Iredale, 1924, has a very small, oval shell (Cretaxinus gen. nov. Both sulci of Mendicula are shallow and the ligament is entirely internal (Zelaya 2010), also unlike in Cretaxinus gen. nov., which has weak sulci but largely external ligament. Adontorhina Berry, 1947, apart from small, oval shells with an internal ligament, differs from Cretaxinus by characteristic granules on the hinge plate of the former (Scott 1986; Barry & McCormick 2007). Axinulus Verrill & Bush, 1898, has a small oval shell which is higher than long (Payne & Allen 1991) and a largely internal ligament, also unlike Cretaxinus gen. nov. The current lack of taxonomically robust characters in the shells of the Thyasiridae leads to problems of generic separation within the family (e.g. Payne & Allen 1991; Oliver & Killeen 2002; Oliver & Sellanes 2005; Oliver & Holmes 2006; Rodrigues et al. 2008). Molecular data suggest that current thyasirid generic definitions might be inadequate and additional morphological studies may result in redefinition of the genera (Taylor et al. 2007). Further, the same data show only a weak separation between larger, chemosymbiotic thyasirids and small (Mendicula Iredale, 1924, Leptaxinus Verrill & Bush, 1898, Adontorhina Berry, 1947, and Axinulus Verrill & Bush, 1898 (Dufour 2005)., Published as part of Hryniewicz, Krzysztof, Little, Crispin T. S. & Nakrem, Hans Arne, 2014, Bivalves from the latest Jurassic-earliest Cretaceous hydrocarbon seep carbonates from central Spitsbergen, Svalbard, pp. 1-66 in Zootaxa 3859 (1) on pages 35-36, DOI: 10.11646/zootaxa.3859.1.1, http://zenodo.org/record/4930112, {"references":["Dufour, S. (2005) Gill anatomy and the evolution of symbiosis in bivalve family Thyasiridae. Biological Bulletin, 208, 200 - 212. http: // dx. doi. org / 10.2307 / 3593152","Sowerby, J. (1821) The Mineral Conchology of Great Britain 4 (1), J. Sowerby, London, 1 - 16, pls. 307 - 318. http: // dx. doi. org / 10.5962 / bhl. title. 14408","Lamarck, J. B. (1818) Histoire naturelle des animaux sans vertebres. Vol. 5, Deterville, Paris, 612 pp.","Iredale, T. (1930) More notes on the marine Mollusca of New South Wales. Records of the Australian Museum, 17, 384 - 407. http: // dx. doi. org / 10.3853 / j. 0067 - 1975.17.1930.773","Gabb, W. M. (1866) Paleontology of California. Vol. 2. Cretaceous and Tertiary fossils. Sect. 1 (Tertiary Invertebrate Fossils). Geological Survey of California, 124 pp., 18 pls.","Payne, C. M. & Allen, J. A. (1991) The morphology of deep-sea Thyasiridae (Mollusca: Bivalvia) from the Atlantic Ocean. Philosophical Transactions: Biological Sciences, 334, 481 - 562. http: // dx. doi. org / 10.1098 / rstb. 1991.0128","Oliver, G. P. & Holmes, A. M. (2007) A new species of Axinus (Bivalvia: Thyasiroidea) from the Baby Bare Seamount, Cascadia Basin, NE Pacific, with a description of the anatomy. Journal of Conchology, 39, 363 - 376.","Oliver, G. P. & Killeen, I. J. (2002) The Thyasiridae (Mollusca: Bivalvia) of the British continental shelf and North Sea oilfields. Biomor Reports, 3, 1 - 73.","Oliver, G. P. & Holmes, A. M. (2006) New species of Thyasiridae (Bivalvia) from chemosynthetic communities in the Atlantic Ocean. Journal of Conchology, 39, 175 - 183.","Rodrigues, C. F., Oliver, G. P. & Cunha, M. R. (2008) Thyasiroidea (Mollusca: Bivalvia) from the mud volcanoes of the Gulf of Cadiz. Zootaxa, 1752, 41 - 56.","Zelaya, D. G. (2009) The genera Thyasira and Parathyasira in the Magellan region and adjacent Antarctic waters (Bivalvia: Thyasiridae). Malacologia, 51, 271 - 290. http: // dx. doi. org / 10.4002 / 040.051.0204","Kamenev, G. M., Nadtochy, V. A. & Kuznetsov, A. P. (2001) Conchocele bisecta (Conrad, 1849) (Bivalvia: Thyasiridae) from cold-water methane-rich areas of the Sea of Okhotsk. The Veliger, 44, 84 - 94.","Okutani, T. (2002) A new thyasirid, Conchocele novaeguinensis n. sp. from a thanatocoenosis associated with a possible cold seep activity off New Guinea. Venus, 61, 141 - 145.","Iredale, T. (1924) Results from Roy Bell's Molluscan collections. Proceedings of the Linnean Society of New South Wales, 49, 179 - 278.","Zelaya, D. G. (2010) The new species of Thyasira, Mendicula and Axinulus (Bivalvia; Thyasiroidea) from Sub-Antarctic and Antarctic waters. Polar Biology, 33, 607 - 616. http: // dx. doi. org / 10.1007 / s 00300 - 009 - 0736 - 9","Berry, S. S. (1947) New Mollusca from the Pleistocene of San Pedro, California - III. Bulletins of American Paleontology, 31, 256 - 275.","Scott, P. H. (1986) A new species of Adontorhina (Bivalvia: Thyasiridae) from the Northeast Pacific, with notes of Adotorhina cyclia Berry, 1947. The Veliger, 29, 149 - 156.","Barry, P. J. & McCormick, G. P. (2007) Two new species of Adontorhina Berry, 1947 (Bivalvia: Thyasiridae) from the Porcupine Bank, off the west coast of Ireland. Zootaxa, 1526, 37 - 49.","Verrill, A. E. & Bush, K. J. (1898) Revision of the deep water Mollusca of the Atlantic Coast of North America, with description of new genera and species, Pt. 1, Bivalvia. Proceedings of the United States National Museum, 20, 775 - 901, pls. 71 - 97.","Oliver, G. P. & Sellanes, J. (2005) New species of Thyasiridae from a methane seepage area off Concepcion, Chile. Zootaxa, 1092, 1 - 20.","Taylor, J. D., Williams, S. T. & Glover, E. A. (2007) Evolutionary relationships of the bivalve family Thyasiridae (Mollusca: Bivalvia), monophyly and superfamily status. Journal of the Marine Biological Association of the United Kingdom, 87, 565 - 574. http: // dx. doi. org / 10.1017 / s 0025315407054409"]}

Cretaxinus hurumi sp. nov. (Figures 13 K���N, 15, 16 A���G) 2011 Thyasira sp. ���Hammer et al., fig. 7a���c, tab. 2. Etymology. After J��rn H. Hurum, leader of 2004���2012 Svalbard expeditions of the Natural History Museum, University of Oslo. Type locality. Seep 9, Knorringfjellet, Spitsbergen, 78��18���49.9���N 16��10���58.9���E. Type mterial. Holotype: PMO 217.277; an internal mould with shell partially preserved, showing a triangular outline, external ornament, a sulcated posterior margin and a thick, short, external ligament. Paratypes: PMO 217.172; an almost complete internal mould showing outline and anterior adductor muscle scar. PMO 217.175; a fragment of an internal mould and silicone rubber cast showing posterior adductor muscle scar and posterior pedal retractor. The silicone rubber cast shows the cardinal area with an elongated resilifer. PMO 217.540; complete internal mould showing the triangular outline, well impressed rounded posterior adductor muscle scar and deep escutcheon. PMO 225.128; an almost complete internal mould showing anterior adductor muscle scar and crosssection through the external ligament and ligament nymphs. PMO 225.136; an internal mould showing very weak anterior adductor muscle scar. Material examined. 56 specimens, all articulated or semi-articulated internal moulds with variable amounts of shell preserved. See Appendix 1 for list of specimens. Dimensions. 23���56.5 mm in length, 12.6���50 mm in height, 19���39 mm in width. See Figure 17 A���D and Appendix 2K for details. Diagnosis. As for the genus. Description. Shell large, subtriangular in outline, up to 56.5 mm long, 50 mm high, and 39 mm wide. Average H/L ratio ��� 0.85, W/L ��� 0.75, and W/H ��� 0.88. Shell less than 0.5 mm thick, covered with commarginal growth lines. Umbonal angle usually larger among smaller specimens, which have concave anterodorsal and posterodorsal margins. Beaks incurved, prosogyrate, not prominent, positioned closer towards the anterior, with average Pl/L ��� 0.67. Umbonal angle slightly acute. Lunule large, deep, heart-shaped. Anterior margin tightly rounded, more angular in larger specimens. Ventral margin curved, with curvature deepest close to mid-line in smaller specimens, progressively displaced towards posterior during growth. Curvature shows some intraspecific variation, from deep and prominent, to shallow and gentle. Posterior extremity weakly pointed, posterodorsal margin sloping, with very weak sulcus. Smaller specimens usually have slightly concave posterodorsal margin, which is more straight in larger specimens. Escutcheon large and deep. Ligament external, thick, short, occupying 1/3 of escutcheon. Hinge plate narrow. Cardinal area with single, elongate groove, probably representing a ligament groove. Lateral dentition not observed. Anterior adductor muscle scar very weak and small, elongated along pallial line, with straight ventral margin and irregular dorsal margin; well impressed in anterior part, fading towards posterior so length of anterior adductor muscle scar cannot be fully ascertained. Anterior pedal retractor scar small and weak, circular, separated from the anterior adductor muscle scar by narrow margin, visible in one specimen only. Posterior adductor muscle scar larger than anterior adductor muscle scar, circular, deeply impressed, displaced towards hinge plate. Posterior pedal retractor small, circular, approximately same size as anterior pedal retractor scar; positioned close to hinge plate and separated from posterior adductor muscle scar by narrow distance. Pallial line entire, weak, marked by pallial muscle scars in some specimens. Internal shell surface covered with fine radial ornament, probably representing traces of descending pallial muscles. Remarks. Cretaxinus hurumi gen. et sp. nov. is the oldest thyasirid species known to date. The slightly younger Valanginian to Hauterivian thyasirid is Lucina ? rouyana d���Orbigny, 1844, from the shelf deposits of Europe and possible seep sites of Grodziszcze beds in the Carpathians (Ascher 1906, p. 164, pl. XIV, fig. 9a���c; Kiel et al. 2008a; Kaim et al. 2013), which has more of a typical Thyasira shape. The Albian Lucina ? sculpta Phillips, 1829, from Southern England (Woods 1907, p. 153, pl. 24, fig. 7���9) has a very distinct shape reminiscent of the genus Axinus Sowerby, 1821 (Taylor et al. 2007). Thyasira tanabei Kiel, Amano & Jenkins, 2008 (a) is known from Albian to Campanian hydrocarbon seeps of Hokkaido, Japan. Thyasira tanabei has a large anterior adductor muscle scar, unlike C. hurumi, but the lack of information about the ligament of T. tanabei makes more detailed comparison difficult. Thyasira sp. from the Cenomanian Kanajirasawa seep of Hokkaido (Kiel et al. 2008a) is known from a single, partially preserved specimen only and, therefore, is also difficult to compare to C. hurumi. Various Campanian thyasirid species from the Western Interior Seaway (Kauffman 1967) differ in shape from C. hurumi, having flattened posterior areas, narrow escutcheons, deeper sulci and more ovate shapes, reminiscent of Recent Thyasira species. Occurrence. Seep 9 (uppermost Ryazanian), Slottsm��ya Member, Svalbard (Tab. 1). Known only from the type locality. Palaeoecology. We infer that Cretaxinus hurumi was a chemosymbiotic and possibly seep-restricted Mesozoic thyasirid. This is supported by the large shell size of C. hurumi. Among modern thyasirids chemosymbiosis is present mainly in species with two gill demibranchs (Dufour 2005) and these usually have large shells, up to around 10 mm for the genera Axinus, Thyasira and Parathyasira, but can reach up to 110 mm in Conchocele (e.g. Payne & Allen 1991; Kamenev et al. 2001; Oliver & Killeen 2002). Large shells provide enough space in the mantle cavity for large symbiont-bearing gills (Taylor & Glover 2010). In contrast, thyasirids with a single gill demibranch are usually asymbiotic (Dufour 2005; Taylor & Glover 2010). These asymbiotic species are much smaller, with sizes of only a few millimeters (Payne & Allen 1991; Oliver & Levin 2006). Cretaxinus hurumi shells are up to 56.5 mm long, and this is very large for the family, which strongly suggests the species had hypertrophied gills suitable for symbiosis with chemoautotrophic bacteria. Smaller chemosymbiotic thyasirids (��� 10 mm in length) are known from seep environments (e.g. Dando et al. 2004), but also occur in non-seep settings with high redox potential, such as organic-rich sediments in fjords (Dando & Spiro 1993), pulpmill effluents (Dando & Southward 1986) and in the vicinity of offshore hydrocarbon production sites (Oliver & Killeen 2002). However, the only Recent thyasirid genus which attains sizes comparable to C. hurumi is Conchocele, and this is closely associated with seeps (Kamenev et. al 2001; Okutani 2002; cf. Weaver 1942; Coan et al. 2000). Another line of evidence indicating that C. hurumi was both chemosymbiotic and seep-restricted comes from absence of the species in contemporary ���normal��� marine sediments on Svalbard (e.g. Sokolov & Bodylevsky 1931; Weir 1933; Birkenmajer et al. 1982), despite being relatively abundant in the hydrocarbon seeps (Hammer et al. 2011). Thyasirids are burrowers (e.g. Dando & Southward 1986; Oliver & Killeen 2002). Chemosymbiotic species dig into fine grained sediment to a depth a few times the length of the shell (Pearson 1972). In these burrows they use a vermiform foot to construct a three dimensional network of downward directed tunnels reaching up to 30 times the length of the shell, which serve as conduits for sulfide-rich pore waters from deeper interstitial levels (Dando & Southward 1986; Zuschin et al. 2001; Oliver & Killeen 2002; Dando et al. 2004; Taylor & Glover 2010). However, they are usually unable to tolerate high sulfide concentrations. Chemosymbiotic thyasirids are also capable of feeding on photosynthetic organic matter if conditions for chemosynthesis become unfavourable (Dando & Spiro 1993). Cretaxinus hurumi was probably a relatively deep burrower, based on similar lines of evidence to the lucinid Tehamatea rasmusseni. Order Venerida Gray, 1854, Published as part of Hryniewicz, Krzysztof, Little, Crispin T. S. & Nakrem, Hans Arne, 2014, Bivalves from the latest Jurassic-earliest Cretaceous hydrocarbon seep carbonates from central Spitsbergen, Svalbard, pp. 1-66 in Zootaxa 3859 (1) on pages 37-41, DOI: 10.11646/zootaxa.3859.1.1, http://zenodo.org/record/4930112, {"references":["Ascher, E. (1906) Die Gastropoden, Bivalven und Brachiopoden der Grodischter Schichten. Beitrage zur Palaontologie und Geologie Osterreich-Ungarns und des Orients, 19, 135 - 167.","Kiel, S., Amano, K. & Jenkins, R. G. (2008 a) Bivalves from Cretaceous cold seep deposits on Hokkaido, Japan. Acta Palaeontologica Polonica, 53, 525 - 537. http: // dx. doi. org / 10.4202 / app. 2008.0310","Kaim, A., Skupien. P. & Jenkins, R. G. (2013) A new Lower Cretaceous hydrocarbon seep locality from the Czech Carpathians and its fauna. Palaeogeography, Palaeoecology, Palaeoclimatology, 390, 42 - 51. http: // dx. doi. org / 10.1016 / j. palaeo. 2013.03.010","Phillips, J. (1829) Illustrations of the geology of Yorkshire. 1 st edition. Printed for John Murray, Ablemarle Street, York, xvi + 192 pp., 24 pls.","Woods, H. (1907) A monograph of the Cretaceous Lamellibranchia. Vol. II. Palaeontographical Society Monographs, 61, 133 - 180, pls. 20 - 27.","Sowerby, J. (1821) The Mineral Conchology of Great Britain 4 (1), J. Sowerby, London, 1 - 16, pls. 307 - 318. http: // dx. doi. org / 10.5962 / bhl. title. 14408","Taylor, J. D., Williams, S. T. & Glover, E. A. (2007) Evolutionary relationships of the bivalve family Thyasiridae (Mollusca: Bivalvia), monophyly and superfamily status. Journal of the Marine Biological Association of the United Kingdom, 87, 565 - 574. http: // dx. doi. org / 10.1017 / s 0025315407054409","Kauffman, E. G. (1967) Cretaceous Thyasira from the western interior of Northern America. Smithsonian Miscellaneous Collections, 152, 1 - 159.","Dufour, S. (2005) Gill anatomy and the evolution of symbiosis in bivalve family Thyasiridae. Biological Bulletin, 208, 200 - 212. http: // dx. doi. org / 10.2307 / 3593152","Payne, C. M. & Allen, J. A. (1991) The morphology of deep-sea Thyasiridae (Mollusca: Bivalvia) from the Atlantic Ocean. Philosophical Transactions: Biological Sciences, 334, 481 - 562. http: // dx. doi. org / 10.1098 / rstb. 1991.0128","Kamenev, G. M., Nadtochy, V. A. & Kuznetsov, A. P. (2001) Conchocele bisecta (Conrad, 1849) (Bivalvia: Thyasiridae) from cold-water methane-rich areas of the Sea of Okhotsk. The Veliger, 44, 84 - 94.","Oliver, G. P. & Killeen, I. J. (2002) The Thyasiridae (Mollusca: Bivalvia) of the British continental shelf and North Sea oilfields. Biomor Reports, 3, 1 - 73.","Taylor, J. D. & Glover, E. A. (2010) Chemosymbiotic Bivalves. In: Kiel, S. (Ed.), The vent and seep biota. Aspects from microbes to ecosystems. Topics in Geobiology, Springer, Dordrecht, Heidelberg, London, New York, pp. 107 - 133.","Oliver, G. P. & Levin, L. (2006) A new species of the family Thyasiridae (Mollusca: Bivalvia) from the oxygen-minimum zone of the Pakistan margin. Journal of the Marine Biological Association of the United Kingdom, 86, 411 - 416. http: // dx. doi. org / 10.1017 / s 0025315406013270","Dando, P. R., Southward, A. J. & Southward, E. C. (2004) Rates of sediment sulphide oxidation by the bivalve mollusk Thyasira sarsi. Marine Ecology Progress Series, 280, 181 - 187. http: // dx. doi. org / 10.3354 / meps 280181","Dando, P. R. & Spiro, B. (1993) Varying nutritional dependence of the thyasirid bivalves Thyasira sarsi and T. equalis on chemoautotrophic symbiotic bacteria, demonstrated by isotope ratios of tissue carbon and shell carbonate. Marine Ecology Progress Series, 92, 151 - 158. http: // dx. doi. org / 10.3354 / meps 092151","Dando, P. R., Southward, A. J. & Southward, E. C. (1986) Chemoautotrophic symbionts in the gills of the bivalve mollusk Lucinoma borealis and the sediment chemistry of its habitat. Proceedings of the Royal Society of London B, 227, 227 - 247. http: // dx. doi. org / 10.1098 / rspb. 1986.0021","Okutani, T. (2002) A new thyasirid, Conchocele novaeguinensis n. sp. from a thanatocoenosis associated with a possible cold seep activity off New Guinea. Venus, 61, 141 - 145.","Weaver, C. E. (1942) Paleontology of the marine Tertiary formations of Oregon and Washington. University of Washington Publications in Geology, 5, 1 - 789.","Coan, E. V., Scott, P. V. & Bernard, F. R. (2000) Bivalve seashells of Western North America. Marine bivalve molluscs from Arctic Alaska to Baja California. Santa Barbara Museum of Natural History Monographs, 2, vii + 764 pp.","Sokolov, D & Bodylevsky, W. (1931) Jura- und Kreidefaunen von Spitsbergen. Skrifter om Svalbard og Ishavet, 35, 1 - 151, pls. 1 - 14.","Weir, J. (1933) Mesozoic fossils from Spitsbergen collected by Dr. G. W. Tyrrell. Transactions of the Royal Society of Edinburgh, 57, 637 - 697, pl. 1.","Birkenmajer, K., Pugaczewska, H. & Wierzbowski, A. (1982) The Janusfjellet Formation (Jurassic - Lower Cretaceous) at Myklegardfjellet, east Spitsbergen. Palaeontologia Polonica, 43, 107 - 140, pls. 37 - 46.","Hammer, O., Nakrem, H. A., Little, C. T. S., Hryniewicz, K., Sandy, M., Hurum, J. H., Druckenmiller, P., Knutsen, E. M. & Hoyberget, M. (2011) Hydrocarbon seeps from close to the Jurassic - Cretaceous boundary, Svalbard. Palaeogeography, Palaeoclimatology, Palaeoecology, 306, 15 - 26. http: // dx. doi. org / 10.1016 / j. palaeo. 2011.03.019","Pearson, T. H. (1972) The effect of industrial effluent from pulp and paper mills on the marine benthic environment. Proceedings of the Royal Society of London. Series B, Biological Sciences, 180, 469 - 485. http: // dx. doi. org / 10.1098 / rspb. 1972.0032","Zuschin, M., Mandic, O., Harzhauser, M. & Pervesler, P. (2001) Fossil evidence for chemoautotrophic bacterial symbiosis in the thyasirid bivalve Thyasira michelottii from the Middle Miocene (Badenium) of Austria. Historical Biology, 15, 223 - 234. http: // dx. doi. org / 10.1080 / 10292380109380594","Gray, J. E. (1854) A revision of the arrangement of the families of bivalve shells (Conchifera). The Annals and Magazine of Natural History, Series 2, 13, 408 - 418. http: // dx. doi. org / 10.1080 / 03745485709496364"]}

Funafutia levukana (E.A. Smith, 1885) Figures 24 E–G Lucina levukana E.A. Smith, 1885: p. 181, pl. 13, fig. 6. Funafutia levukana (E.A. Smith, 1885) — Glover & Taylor, 2001: p. 286, figs. 22 A-D; Tröndlé & Boutet, 2009: p. 8. Material examined. More than fifty single valves from EI and SyG (BK), plus specimens from the Marquesas Islands (MHU). Diagnosis. Shell small (up to 6 mm in length), suborbicular, equivalve, inequilateral, not fragile. Umbones elevated. Exterior surface of irregularly spaced prominent, rounded commarginal lamellae, microscopic radials. Interior smooth with continuous pallial line; margins finely crenulate. Hinge stout, consisting of two cardinals in the LV, and one cardinal in the RV with prominent posterior and anterior laterals. Color white. Remarks. The oblique shape, lamellate sculpture with microscopic radials, the crenulated margin and the hinge configuration closely approach the type species Funafutia levukana (E.A. Smith 1885). Species within the genus Levukana are typically known from shallow water to 40 m, with a size of 6 mm. The EI species is known from 20–100 m, also from caves in 35–40 m (Motu Tantara) with a maximum size of 5 mm. Although the EI material has a somewhat denser commarginal sculpture with weaker radials and a slightly less pronounced anterior lateral in the LV, J. Taylor, (pers. comm., 2010) confirmed the specimens to be within the normal variability of F. levukana. Sizes and depths are comparable. Most likely, this species conforms to Kay (1995: 155) Lucina species from Easter Island. Habitat. Commonly found at many locations around EI and SyG, in fine sand, from 20–100 m. Distribution. Funafutia levukana is known from eastern Africa to the Marquesas Islands, but has not been recorded from the Hawaiian Islands. The presence of this species on Easter and Salas y Gómez Islands represents a range extension— E4., Published as part of Raines, Bret & Huber, Markus, 2012, 3217, pp. 1-106 in Zootaxa 3217 on page 50, {"references":["Smith, E. A. (1885) Report on the Lamellibranchiata collected. Reports of the Scientific Results of the Exploratory Voyage of H. M. S. Challenger, Zoology, 13 (35), 1 - 341.","Glover, E. & Taylor, J. D. (2001) Systematic revision of Australian and Indo-Pacific Lucinidae (Mollusca: Bivalvia): Pillucina, Wallucina and descriptions of two new genera and four new species. Records of the Australian Museum, 53, 263 - 292.","Trondle, J. & Boutet, M. (2009) Inventory of marine molluscs of French Polynesia. Atoll Research Bulletin, 570, 1 - 87.","Kay, E. A. (1995) Pacific island marine mollusks: systematics. In: Maragos, J. E. et al. (Eds), Marine and coastal biodiversity in the tropical island Pacific region. Honolulu, 135 - 159."]}

Ctena bella (Conrad, 1837) Figures 24 A–D Lucina bella Conrad, 1837: p. 254, pl. 19, fig. 11. Ctena bella (Conrad, 1837) — Dall et al., 1938: p. 129, pl. 35, figs. 1–8; Kay, 1979: p. 543, figs. 176 A–D; Preece, 1995: p. 350; Tröndlé & Boutet, 2009: p. 7; Severns, 2011: p. 468, pl. 214, fig. 2. Codakia (Epicodakia) bella (Conrad, 1837) — Rehder, 1980: p. 110. Ctena bella (Conrad, [sic] 1834)— Brook & Marshall, 1998: p. 212; Spencer et al., 2011: p. 1. Epicodakia bella (Conrad, 1837) — Okutani, 2000: p. 929, pl. 462, fig. 5. Material examined. Several hundred articulated specimens and single valves from EI and SyG (BK), plus specimens from the Hawaiian Islands (MHU), Marquesas Islands (MHU), Australia (MHU) and Pitcairn Island (BK). Diagnosis. Shell small (up to 20 mm in length) broadly ovate to suborbicular shape, equivalve, inequilateral, not fragile. Umbones somewhat elevated; lunule moderately impressed and elongate. Exterior surface of rounded radiating ribs crossed by commarginal ridges forming low elongate nodules on the ribs. Interior muscle scars unequal, with pallial sinus running nearly continuous; margin crenulate. Hinge with two cardinals, which are bifid in the right posterior and left anterior, and opposing laterals in each valve. Color creamy white to pale yellow. Remarks. The EI specimens conform well to the Hawaiian material. Dall et al. (1938) corrected the erroneous original type locality for C. bella from San Diego to the Hawaiian Islands. The Hawaiian species was accepted by J. Taylor, (pers. comm., 2010) to represent bella. The Japanese Ctena delicatula (Pilsbry, 1904), is a similar, but a morphologically distinct species and most noticeable in adult valves by having finer radial ribs and fewer commarginal ridges. Habitat. Commonly found at many locations around EI and SyG, in sand and rubble, from 10–50 m. Distribution. Ctena bella is widely distributed throughout the Indo-Pacific, ranging from the Hawaiian Islands to the Kermadec Islands to include the Society Islands, Marquesas Islands, Tuamotu Archipelago, Gambier Islands, Austral Islands, eastern Australia, Norfolk Island, and Pitcairn Islands, as well as Easter and Salas y Gómez Islands— E5., Published as part of Raines, Bret & Huber, Markus, 2012, 3217, pp. 1-106 in Zootaxa 3217 on pages 48-49, {"references":["Conrad, T. A. (1837) Descriptions of new marine shells, from upper California. Journal of the Academy of Natural Sciences of Philadelphia, 7, 227 - 268.","Dall, W. H., Bartsch, P. & Rehder, H. A. (1938) A manual of the recent and fossil marine pelecypod mollusks of the Hawaiian Islands. Bernice P. Bishop Museum Bulletin, 153, 1 - 33.","Kay, E. A. (1979) Hawaiian Marine Shells. Reef and shore fauna of Hawaii Sec. 4: Mollusca. Oahu, Hawaii (Bishop Museum Press), 653 pp.","Preece, R. C. (1995) The composition and relationships of the marine molluscan fauna of the Pitcairn Islands. Biological Journal of the Linnean Society, 56, 339 - 358.","Trondle, J. & Boutet, M. (2009) Inventory of marine molluscs of French Polynesia. Atoll Research Bulletin, 570, 1 - 87.","Severns, M. (2011) Shells of the Hawaiian Islands. The Sea Shells. ConchBooks, Hackenheim, Germany, 564 pp.","Rehder, H. A. (1980) The marine mollusks of Easter Island (Isla de Pascua) and Sala y Gomez. Smithsonian Contributions to Zoology, Number 289, 167 pp.","Brook, F. J. & Marshall, B. A. (1998) Appendix: Checklist of benthic coastal marine chitons, bivalves, gastropods and cephalopods of the northern Kermadec Islands. In. Brook, F. J. (1998) The coastal molluscan fauna of the northern Kermadec Islands, Southwest Pacific Ocean. Journal of the Royal Society of New Zealand, 28 (2), 185 - 233.","Spencer, H. G., Willan, R. C., Marshall, B. & Murray, T. J. (2011) Checklist of the recent Mollusca recorded from the New Zealand exclusive economic zone. Available from: http: // www. molluscs. otago. ac. nz / index. html (May 2011).","Okutani, T., (Ed) (2000) Marine Mollusks in Japan. Tokai University Press, Tokyo, Japan, 1224 pp.","Pilsbry, H. A. (1904). New Japanese marine Mollusca. Pelecypoda. Proceedings of the Academy of Natural Sciences, Philadelphia, 56, 550 - 561."]}

Genus Beauvoisina gen. nov. Type species: Beauvoisina carinata sp. nov., from the late Jurassic seep deposits at Beauvoisin, southeastern France. Diagnosis: Shell very large (up to 140 mm), oval, elongate-oval, to nearly rectangular in shape; beak displaced towards posterior in more elongate specimens; sculpture of irregular commarginal ribs; lunule asymmetric, broader in right valve, bordered by ridge in each valve; escutcheon elongate-lenticular. Radial striations on interior shell surface, many of which start dorsally with a deep pit; ventral third of shell with deep commarginal grooves apparently corresponding with growth rings on shell’s exterior. Hinge with two cardinal teeth in each valve, anterior tooth smaller and vertical, posterior tooth bigger and with posteroventral orientation; nymph straight or slightly convex, slightly longer than three-fifths of length of escutcheon. Etymology: For the type locality of the type species at Beauvoisin, southeastern France.

Beauvoisina carinata sp. nov. (Fig 10) 1985 large bivalves, Gaillard et al., pl. 1, fig. 7. 1990 Lucinacea, Rolin et al., figs. 5, 6. 1992 Lucinid bivalve, Gaillard et al., fig. 7a. Diagnosis: As for the genus. Holotype: FSL 286 459, L = 42 mm, H = 34 mm, W = 22 mm; illustrated on Figs. 10A, J. Paratypes: The figured specimens FSL 286 460 – 286 463. Type locality: Seep deposits at Beauvoisin, Drôme, France, 44°18’N, 5°12’E; Late Jurassic, Oxfordian. Material: The type material and numerous additional specimens from the late Jurassic seep carbonates at Beauvoisin, southeastern France, deposited in the FSL. Etymology: For its carinate lunule. Remarks: Beauvoisina carinata is the earliest record of a lucinid from a methane seep. Shells larger than ca. 50 mm are usually crushed. The adductor muscle scars are extremely weak: although several wellpreserved internal molds were available, neither the scars nor the pallial line could be detected (see figs. 10H, I, K, L). In this respect this species resembles a similarly shaped lucinid from the Early Cretaceous (Hauterivian) Crimean methane seep site, which also has very weak muscle attachment scars (Kiel and Peckmann 2008). The Crimean species differs by lacking the elongate nymph of the Beauvoisin species. The hinge of Beauvoisina carinata differs from that of the Late Cretaceous North American Nymphalucina occidentalis Morton, 1842 by its much narrower nymph; further, N. occidentalis has a small cardinal tooth pointing posteriorly, that is lacking in Beauvoisina carinata (Speden 1970). The large, mid-Cretaceous lucinid Ezolucina inflata (Kanie and Nishida, 2000) has a much higher umbo than B. carinata and a more angular shape, resembling that of vesicomyids rather than oval shape of B. carinata (see Amano et al. 2008). Another large, seep-related lucinid with late Mesozoic members is Nipponothracia, which differs from B. carinata by its edentulous hinge (Kanie and Sakai 1997; Kiel et al. 2008). Along with the tall gastropod that we describe as Humptulipsia macsotayi herein, Thieuloy (1972) reported a large bivalve from the early Cretaceous seeps at Rottier, southeastern France. This bivalve was identified (but not figured) by Macsotay (1980) as the lucinid Pseudomiltha aff. germani. The published figures of this species are insufficient for identification and our own sampling at this site revealed only fragmentary material. However, Thieuloy’s (1972) image shows a specimen with radial sculpture, which is not seen in B. carinata., Published as part of Kiel, Steffen, Campbell, Kathleen A. & Gaillard, Christian, 2010, New and little known mollusks from ancient chemosynthetic environments, pp. 26-48 in Zootaxa 2390 (1) on pages 41-42, DOI: 10.11646/zootaxa.2390.1.2, http://zenodo.org/record/5305157, {"references":["Kiel S. & Peckmann J. (2008) Paleoecology and evolutionary significance of an Early Cretaceous Peregrinella - dominated hydrocarbon-seep deposit on the Crimean Peninsula. Palaios, 23, 751 - 759.","Morton S. G. (1842) Description of some new species of organic remains of the Cretaceous group in the United States, with a tabular view of the fossils hitherto discovered in this formation. Journal of the Academy of Natural Sciences of Philadelphia, 8, 207 - 227.","Speden I. G. (1970) The type Fox Hills Formation, Cretaceous (Maestrichtian), South Dakota. Part 2. Systematics of the Bivalvia. Peabody Museum of Natural History Yale University, Bulletin, 33, 1 - 222.","Kanie Y. & Nishida T. (2000) New species of chemosynthetic bivalves, Vesicomya and Acharax, from the Cretaceous deposits of northwestern Hokkaido. Science Report of the Yokosuka City Museum, 47, 79 - 84.","Thieuloy J. - P. (1972) Biostratigraphie des lentilles a peregrinelles (Brachiopodes) de l'Hauterivien de Rottier (Drome, France). Geobios, 5, 5 - 53.","Macsotay O. (1980) Molluscques benthiques du Cretace inferieur. Une methode de correlation entre la Tethys mesogeenne et le domaine paleocaraibe (Venezuela). PhD Thesis, Universite Claude-Bernard, Lyon."]}

Genus Beauvoisina gen. nov. Type species: Beauvoisina carinata sp. nov., from the late Jurassic seep deposits at Beauvoisin, southeastern France. Diagnosis: Shell very large (up to 140 mm), oval, elongate-oval, to nearly rectangular in shape; beak displaced towards posterior in more elongate specimens; sculpture of irregular commarginal ribs; lunule asymmetric, broader in right valve, bordered by ridge in each valve; escutcheon elongate-lenticular. Radial striations on interior shell surface, many of which start dorsally with a deep pit; ventral third of shell with deep commarginal grooves apparently corresponding with growth rings on shell’s exterior. Hinge with two cardinal teeth in each valve, anterior tooth smaller and vertical, posterior tooth bigger and with posteroventral orientation; nymph straight or slightly convex, slightly longer than three-fifths of length of escutcheon. Etymology: For the type locality of the type species at Beauvoisin, southeastern France., Published as part of Kiel, Steffen, Campbell, Kathleen A. & Gaillard, Christian, 2010, New and little known mollusks from ancient chemosynthetic environments, pp. 26-48 in Zootaxa 2390 (1) on page 41, DOI: 10.11646/zootaxa.2390.1.2, http://zenodo.org/record/5305157

Twelve mollusk species from late Jurassic to Oligocene cold seep deposits are described and illustrated. Nine of them are new, two have already been named, two new genera are introduced, and one species is described only in open nomenclature. Puncturella (sensu lato) mcleani sp. nov. and Fissurella (sensu lato) bipunctata Stanton, 1895 are the only confirmed fissurellids in fossil cold seeps. The sutilizonid Triassurella goederti sp. nov. is similar to the modern ventinhabiting Sutilizona and the Late Triassic shallow-water reef-inhabitant Triassurella carnica. A smooth, late Jurassic neritid is the oldest neritid from fossil seeps and probably represents an independent neritid radiation into the seep environment, without close phylogenetic connection to the modern Bathynerita. The four new abyssochrysoid caenogastropods Humptulipsia macsotayi, Hokkaidoconcha novacula, Paskentana anistratenkorum, and P. umbilicata significantly extend the stratigraphic and geographic ranges of these apparently seep-restricted genera. Four bivalves are described, including the new modiomorphid Caspiconcha rubani from the early Cretaceous and the new bathymodioline Bathymodiolus (s.l.) palmarensis from the Oligocene. Among the lucinids, the oldest seep-inhabiting lucinid (late Jurassic) is described as Beauvoisina carinata gen. et sp. nov.; the new genus Cubatea is introduced for an Oligocene lucinid from Cuba. It is suggested that Caspiconcha, Paskentana, and hokkaidoconchids constitute the core of a seeprestricted fauna that inhabited seeps worldwide from (at least) late Jurassic to early Cretaceous time. These taxa are, at the family level, phylogenetically unrelated to the modern vent and seep fauna.

Lam, Katherine, Morton, Brian, Leung, K.F. (2008): Shell-bearing Mollusca (Bivalvia and Gastropoda) from submarine caves in Hong Kong. Journal of Natural History 42 (9-12): 927-952, DOI: 10.1080/00222930701862674, URL: http://dx.doi.org/10.1080/00222930701862674

Genus Myrtina n.gen. TYPE SPECIES. — Myrtina porcata n. sp. (here designated). ETYMOLOGY. — Myrtina diminutive of Myrtea. DIAGNOSIS. — Shells small to medium in size, relatively flat, sub-circular, dorsal anterior margin with more or less elevated commarginal lamellae. Sculpture of fine to prominent, closely spaced, commarginal lamellae. Radial ribs absent. Lunule lanceolate to heart-shaped, asymmetric with larger part in right valve. Two cardinal teeth in left valve and single tooth in right valve; indistinct lateral teeth present in both valves. Anterior adductor scar short, detached for about 1/5 of length. Pallial line entire. Shell margin smooth. REMARKS Alucinoma Habe, 1958 is similar in outline to Myrtina n. gen. but the type species, A. soyae Habe, 1958, from Japan, lacks hinge teeth and the thin commarginal lamellae are prominent largely on the posterior and anterior dorsal margins of the shell.

Ferrocina multiradiata n. sp. (Figs 23C; 30) TYPE MATERIAL. — Holotype: 1 sh, L 11.2 mm, H 10.1 mm, T 3.3 mm (MNHN). Paratypes: from type locality, 1 LV, L 9.5 mm, H 7.7 mm, T 2.2 mm. — Vanuatu, stn DW 1000, 90- 200 m, 18°49’S, 169°00’E, 1 LV, L 18.2 mm, H 16.6 mm, T 5.0 mm (MNHN). TYPE LOCALITY. — Vanuatu, MUSORSTOM 8, stn DW 999, 18°49’S, 169°00’E, 80- 110 m. ETYMOLOGY. — Multiradiata refers to the many fine, radial ribs of this species. MATERIAL EXAMINED. — Koumac. 1 stn, 80-120 m, 1 v. Touho. 2 stn, 80-140 m, 4 v. Fiji. South of Viti Levu, MUSORSTOM 10, several stn DW 1374, CP 1384, CP 1387, CP 1386, CP 1389, CP 1390, between 229-417 m (MNHN). DISTRIBUTION. — New Caledonia, Vanuatu, Fiji, from 80-400 m DESCRIPTION Shell small, rusty red, H to 16.6 mm, L to 18.0 mm, thin shelled, subovate, longer than high H/L 0.90, posterior margin quadrate, slightly inflated (T/L 0.28). Umbones low, slightly posterior of centre. Sculpture of numerous (c. 60), closely spaced, fine, rounded, radial ribs, that occasionally divide. Ribs crossed by low, fine, irregular, commarginal threads. Ribs obsolete on anterior and posterior dorsal areas. Posterior sulcus marked by lack of ribs. Lunule lanceolate, slightly asymmetric, RV extends into LV. Hinge plate narrow, RV with single, small cardinal tooth, a single small, elongate anterior lateral, and a small posterior lateral fold. LV with two very small cardinal teeth, anterior cardinal twice size of posterior cardinal, anterior lateral indistinct, posterior lateral absent. Ligament short, inset. Anterior adductor scar medium length, detached for 1/3 of length. Posterior scar ovate. Pallial line wide, continuous. Shell inside pallial line dull with radial striations; outside pallial line, glossy, shell margin crenulate, with ribs extending deeply into shell interior. Internal coloration rusty red.

Genus Anodontia Link, 1807 Anodontia Link, 1807: 156. TYPE SPECIES. — A. alba Link, 1807 (monotypy). DIAGNOSIS. — Shells small to large, relatively thin-shelled, usually white, globose, subcircular, exterior smooth with irregular commarginal growth increments. Hinge teeth absent. Ligament internal either in a groove or laterally inset. Anterior adductor muscle scar generally long and in most species detached from pallial line for at least half of length. Pallial line entire or divided. REMARKS Full synonymies, descriptions and distribution maps for species and genera in the Anodontia group are given in Taylor & Glover (2005). Twenty-five species are recognised worldwide., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on page 112, DOI: 10.5281/zenodo.5392295, {"references":["LINK H. F. 1807. - Beschreibung der Naturalien-Sammlung der Universitat Rostock. Universitat zu Rostock, Rostock, 160 p.","TAYLOR J. D. & GLOVER E. A. 2005. - Cryptic diversity of chemosymbiotic bivalves: a systematic revision of worldwide Anodontia (Mollusca: Bivalvia: Lucinidae). Systematics and Biodiversity 3: 281 - 338."]}

Glover, Emily A., Taylor, John D. (2007): Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou. Zoosystema 29 (1): 109-181, DOI: http://doi.org/10.5281/zenodo.5392295, {"references":["ADAMS A. 1855. - Descriptions of twenty-five new species of shells from the collection of Hugh Cuming Esq. Proceedings of the Zoological Society of London 1855: 221-227.","BARNES P. A. G. & HICKMAN C. S. 1999. - Lucinid bivalves and marine angiosperms: a search for causal relationships, in WALKER D. I. & WELLS F. E. (eds), The Seagrass Flora and Fauna of Rottnest Island,Western Australia. Western Australian Museum, Perth: 215- 238.","BIELER R. & MIKKELSEN P. M. 2004. - Marine bivalves of the Florida Keys: a qualitative faunal analysis based on original collections, museum holdings and literature data. Malacologia 46: 503-544.","BOUCHET P.1994. - Atelier Biodiversite recifale, Expedition Montrouzier,Touho-Koumac, Nouvelle-Caledonie 23 aout-5 novembre 1993. ORSTOM, Centre de Noumea, Rapports de Missions, Sciences de la Mer, Biologie marine 24: 1-63.","BOUCHET P., HEROS V., LE GOFF A., LOZOUET P. & MAESTRATI P. 2001. - Atelier Biodiversite Lifou 2000, grottes et recifs coralliens. Rapport de mission, Paris, 110 p.","BOUCHET P., LOZOUET P., MAESTRATI P. & HEROS V. 2002. - Assessing the magnitude of species richness in tropical marine environments: exceptionally high numbers of molluscs at a New Caledonia site. Biological Journal of the Linnean Society 75: 421-436.","BRETSKY S. S. 1976. - Evolution and classification of the Lucinidae (Mollusca; Bivalvia). Palaeontographica Americana 8 (50): 219-337.","CALLENDER W. R. & POWELL E. N. 1997. - Autochthonous death assemblages from chemautotrophic communities at petroleum seeps: palaeoproduction, energy flow and implications from the fossil record. Historical Biology 12: 165-198.","CARY S. C., FRY B., FELBECK H. & VETTER R. D. 1989. - Habitat characterization and nutritional strategies of the endosymbiont-bearing bivalve Lucinoma aequizonata. Marine Ecology Progress Series 55: 31-45.","CHAVAN A. 1937. - Essai critique de classification des lucines. Journal de Conchyliologie 81: 133-153; 198-216; 237-282.","CHAVAN A. 1938. - Essai critique de classification des lucines. Journal de Conchyliologie 82: 59-97; 105-130; 215-241.","CHAVAN A. 1969. - Superfamily Lucinacea Fleming, 1828, in MOORE R. C. (ed.), Treatise on Invertebrate Paleontology, Part N, Mollusca 6, Bivalvia, vol. 2. Geological Society of America and University of Kansas, Boulder, Colorado: N491-N518.","COAN E.V., SCOTT P.V.&BERNARD F.R.2000. - Bivalve Seashells of Western North America. Santa Barbara Museum of Natural History, Santa Barbara, 764 p.","CONRAD T. A. 1837. - Descriptions of new marine shells, from Upper California. Collected by Thomas Nuttall Esq. Journal Academy of Natural Sciences, Philadelphia 7: 227-268.","COSEL R. VON 2006. - Taxonomy of tropical West African bivalves VI. Remarks on Lucinidae (Mollusca, Bivalvia), with descriptions of six new genera and eight new species. Zoosystema 28 (4): 805-851.","COTTON B. C. 1961. - The Molluscs of South Australia. Part I. The Pelecypoda. South Australian Branch of the British Science Guild, Adelaide, 363 p.","DALL W. H. 1901. - Synopsis of the Lucinacea and of the American species. Proceedings of the United States National Museum 23: 779-833.","DALL W. H., BARTSCH P. & REHDER H. A. 1938. - A manual of the Recent and fossil marine pelecypod mollusks of the Hawaiian Islands. Bulletin of the Bernice P. Bishop Museum 153: 1-233.","DEKKER H. & GOUD J. 1994. - Review of the living Indo-West-Pacific species of Divaricella sens auct. With descriptions of two new species and a summary of species from other regions. Vita Marina 42: 115-136.","DESHAYES M. G. P. 1832. - Encyclopedie methodique. Histoire naturelle des vers, par Bruguiere et de Lamarck. Volume 2 (2). Agasse, Paris: 145-584.","DESHAYES M. G. P. 1863. - Conchyliologie de l'Ile de la Reunion. Dentu, Paris, 144 p.","DISTEL D. L. 1998. - Evolution of chemoautotrophic endosymbioses in bivalves. Bioscience 48: 277-286.","DUNKER W.1882. - Index Molluscorum Maris Japonici. Novitates Conchologicae, Supplement 7: 1-301.","FINLAY H. J. 1927. - New specific names for Austral Mollusca. Transactions of the New Zealand Institute 57: 488-533.","FISHER C. R. 1990. - Chemoautotrophic and methanotrophic symbioses in marine invertebrates. Reviews in Aquatic Sciences 2: 399-436.","FRENKIEL L., GROS O. & MOUEZA M. 1996. - Gill structure in Lucina pectinata (Bivalvia: Lucinidae) with reference to hemoglobin in bivalves with symbiotic sulphur-oxidising bacteria. Marine Biology 125: 511-524.","GLOVER E. A. & TAYLOR J. D. 1997. - New species and records of Rastafaria and Megaxinus from the western Indian Ocean and Red Sea, with a reappraisal of Megaxinus. Journal of Conchology 36: 1-18.","GLOVER E. A. & TAYLOR J. D. 2001.- Systematic revision of Australian and Indo-Pacific Lucinidae (Mollusca: Bivalvia): Pillucina, Wallucina and descriptions of two new genera and four new species. Records of the Australian Museum 53: 263-292.","GLOVER E. A., TAYLOR J. D. & ROWDEN A. A. 2004. - Bathyaustriella thionipta, a new lucinid bivalve from a hydrothermal vent on the Kermadec Ridge, New Zealand and its relationship to shallow-water taxa (Bivalvia: Lucinidae). Journal of Molluscan Studies 70: 283-295.","GOULD A. 1850. - Shells collected by the United States Exploring Expedition under the command of Charles Wilkes. Proceedings of the Boston Society of Natural History 3: 252-256.","GOULD A. 1852. - Mollusca and shells, in United States Exploring Expedition during theYears 1839-1842 under the Command of Charles Wilkes, USN. Volume 12. Sherman, Philadelphia, 510 p.","HABE T.1977. - Systematics of Mollusca in Japan, Bivalvia and Scaphopoda. Hokuryukan, Tokyo, 372 p.","HEDLEY C. 1899. - The Mollusca of Funafuti. Part II. Pelecypoda and Brachiopoda. Memoirs of the Australian Museum 3: 491-510.","HEDLEY C. 1909. - Mollusca from the Hope Islands, North Queensland. Proceedings of the Linnean Society of New South Wales 34: 420-466.","HEDLEY C. 1913. - Studies on Australian Mollusca. Part XI. Proceedings of the Linnean Society of New South Wales 38: 258-339.","HICKMAN C. S. 1994. - The genus Parvilucina in the Eastern Pacific: making evolutionary sense of a chemosymbiotic species complex. Veliger 37: 43-61.","HICKMAN C. S. & BARNES P. A. G. 1999. - Fossil lucinid bivalves of Rottnest Island: anomalous Late Quaternary geographic distributions,in WALKER D. I. & WELLS F. E. (eds), The Seagrass Flora and Fauna of Rottnest Island,Western Australia. Western Australian Museum, Perth: 239-245.","IREDALE T. 1924. - Results from Roy Bell's molluscan collections. Proceedings of the Linnean Society of New South Wales 49: 179-278.","IREDALE T.1930. - More notes on the marine Mollusca of New South Wales. Records of the Australian Museum 17: 384-407.","IREDALE T.1936. - Australian molluscan notes: No. 2. Records of the Australian Museum 19: 267-340.","IREDALE T. 1937. - Middleton and Elizabeth Reefs, South Pacific Ocean. Mollusca. Australian Zoologist 8: 232-261.","ISSEL A. 1869. - Malacologia del Mare Rosso, richerche zoologiche e paleontologiche. Editori della Biblioteca Malacologia, Pisa, 387 p.","JOHNSON R. 1964. - The Recent Mollusca of Augustus Addison Gould. Bulletin of the United States National Museum 239: 1-182.","KAY E. A. 1979. - Hawaiian marine shells. Bernice P. Bishop Museum Special Publication 64 (4): 1-652.","KEEN A. M. 1971. - Seashells of Tropical West America; Marine Mollusks from Baja California to Peru. 2nd ed. Stanford University Press, Stanford, California, 1064 p.","KURODA T., HABE T.&OYAMA K. 1971. - The Seashells of Sagami Bay. Maruzen, Tokyo, 489 p.","LAMPRELL K. & WHITEHEAD T. 1992. - Bivalves of Australia. Crawford House Press, Bathurst, Australia, 182 p.","LAMPRELL K. & HEALY J. 1998. - Bivalves of Australia. Volume 2. Backhuys Publishers, Leiden, 288 p.","LAMY E. 1920. - Revision des Lucinacea vivants du Museum d'Histoire naturelle de Paris. Journal de Conchyliologie 65: 71-222.","LAMY E. 1921. - Revision des Lucinacea vivants du Museum d'Histoire naturelle de Paris. Journal de Conchyliologie 65: 223-388 (dated 1920, published 1921).","LEBATA J. H. L. 2000. - Elemental sulfur in the gills of the mangrove mud clam Anodontia edentula (family Lucinidae). Journal of Shellfish Research 19: 241- 245.","LINK H. F. 1807.- Beschreibung der Naturalien-Sammlung der Universitat Rostock. Universitat zu Rostock, Rostock, 160 p.","LINNAEUS C. 1758. - Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis. Tomus 1, 10th ed. L. Salvii, Stockholm, 824 p.","LYNGE H. 1909. - The Danish Expedition to Siam 1899-1900. IV. Marine Lamellibranchiata.Kongelige Danske Videnskabernes Selskabs Skrifter 5: 101-299.","LUTAENKO K. A. 2000. - Russian contributions to studies of Vietnamese bivalves. Part 2. List of species recorded by Russian authors or stored in museums. Phuket Marine Biological Center Special Publication 21: 361-390.","MAES V. O. 1967. - The littoral marine mollusks of Cocos Keeling Islands (Indian Ocean). Proceedings of the Academy of Natural Sciences of Philadelphia 119: 93-217.","MARWICK J. 1929. -Tertiary molluscan fauna of Chatton, Southland. Transactions of the New Zealand Institute 59: 903-934.","MATSUKUMA A. 2000. - Lucinidae, Ungulinidae, Thyasiridae, in OKUTANI T.(ed.), Marine Mollusks in Japan. Tokai University Press, Tokyo: 929-937.","MAY W. L. 1903. - On Tenison-Woods types in the Tasmanian Museum, Hobart.Proceedings of the Royal Society of Tasmania 1902: 106-114.","MELVILL J. C. & STANDEN R. 1895. - Notes on a collection of shells from Lifou and Uvea, Loyalty Islands, formed by the Rev. James and Mrs Hadfield, with list of species. Journal of Conchology 8: 84-132.","MELVILL J. C. & STANDEN R. 1899. - Report on the marine Mollusca obtained during the first expedition of Professor A. C. Haddon to the Torres Strait in 1888-89. Journal of the Linnean Society, Zoology 27: 150-206.","MORCH O. A. L. 1853. - Catalogus Conchyliorum,reliquit d'Alphonso d'Aguirra & Gadea Comes de Yoldi. 2. Ludovici Kleini, Hafniae, 74 p.","MORCH O. A. L. 1861. - Beitrage zur Molluskenfauna Central-Amerika's. Malacozoologische Blatter 7: 171- 213.","MUHLFELD, MERGELE VON J. K. 1811. - Entwurf eines neuen Systems der Schalthiergehause. Magazin Gesellschaft Naturforschender Freunde Berlin 5: 38-72.","NICOL D. 1950. - Recent species of the lucinoid pelecypod Fimbria. Journal of the Washington Academy of Sciences 40: 82-87.","OLIVER P. G. 1992. - Bivalved Seashells of the Red Sea. Verlag Christa Hemmen, Wiesbaden; National Museum of Wales, Cardiff, 330 p.","OLIVER P. G., HOLMES A. M., KILLEEN I. J., LIGHT J. M. & WOOD H. 2004. - Annotated checklist of the marine Bivalvia of Rodrigues. Journal of Natural History 38: 3229-3272.","PAULAY G. 2003. - Marine Bivalvia (Mollusca) of Guam. Micronesica 35-36: 218-243.","PHILIPPI R. A. 1847. - Lucina. Abbildungen und Beschreibungen neuer oder wenig gekannter Conchylien. Volume 2. T. Fischer, Casel: 205-207.","PHILIPPI R. A. 1850. - Lucina. Abbildungen und Beschreibungen neuer oder wenig gekannter Conchylien. Volume 3. T. Fischer, Casel. : 101-105.","PILSBRY H. A. 1921. - Marine Mollusks of Hawaii - XIV, XV. Proceedings of the Academy of Natural Sciences of Philadelphia 72: 360-382.","REEVE L. A. 1850. - Monograph of the genus Lucina. Conchologica Iconica vol. 6. Reeve, Benham & Reeve, London, 11 pls.","REID R. G. B. 1990. - Evolutionary implications of sulphide-oxidising symbioses in bivalves,in MORTON B. (ed.), The Bivalvia - Proceedings of a Memorial Symposium in Honour of Sir Charles Maurice Yonge, Edinburgh, 1986. Hong Kong University Press, Hong Kong: 127-140.","RICHER DE FORGES B. 1991. - Les fonds meubles des lagons de Nouvelle-Caledonie : generalites et echantillonnages par dragages,in Le benthos des fonds meubles des lagons de Nouvelle-Caledonie. Collection Etudes et Theses, ORSTOM, Paris 1: 7-148.","ROBBA E., GERONIMO I. D., CHAIMANEE N., NEGRI M. P. & SANFILIPPO R. 2002. - Holocene and Recent shallow soft-bottom mollusks from the northern Gulf of Thailand area: Bivalvia. Bolletino Malacologico 38: 49-132.","SACCO F. 1901. - I molluschi dei terreni terziarii del Piemonte e della Liguria. Parte 29. Clausen, Torino, 216 p.","SALISBURY A. E. 1934. - A new species of Lucina. Journal of Conchology 20: 58.","SALVAT B. 1972. - La faune benthique du lagon de l'atoll de Reao (Tuamotu, Polynesie). Cahiers du Pacifique 16: 31-109.","SCOPOLI G. A. 1777. - Introductio ad historiam naturalum sistens genera lapidum, plantarum, et animalium. Gerle, Prague, 506 p.","SMITH E. A. 1885. - Report on the Lamellibranchiata collected by H.M.S. Challenger during the years 1873-76. Report of the Scientific Results of the Voyage of H.M.S. Challenger 1873-76 13: 1-341.","SOTTO F.B. & COSEL R.VON 1982. - Some commercial bivalves of Cebu, Philippines. The Philippine Scientist 19: 43-101.","SPENCER H. G. & WILLAN R. C. 1996. - The marine Fauna of New Zealand: index to the fauna. Mollusca. New Zealand Oceanographic Institute Memoir 105: 1-125.","SWENNEN C., MOOLENBEEK R. G., RUTTANADAKUL N., HOBBELINK H., DEKKER H. & HAJISAMAE S. 2001. - The molluscs of the southern Gulf of Thailand. Thai Studies in Biodiversity 4: 1-210.","TAYLOR J. D. & GLOVER E. A. 1997. - The lucinid bivalve genus Cardiolucina (Mollusca, Bivalvia, Lucinidae): systematics, anatomy and relationships. Bulletin of the Natural History Museum, London (Zoology) 63: 93-122.","TAYLOR J. D. & GLOVER E. A. 2000 - Functional anatomy, chemosymbiosis and evolution of the Lucinidae, in HARPER E. M., TAYLOR J. D. & CRAME J. A. (eds), The evolutionary biology of the Bivalvia. Geological Society Special Publication 177: 207-225.","TAYLOR J. D. & GLOVER E. A. 2002. - Lamellolucina: a new genus of lucinid bivalve with four new species from the Indo-West Pacific. Journal of Conchology 37: 317-336.","TAYLOR J. D. & GLOVER E. A. 2005. - Cryptic diversity of chemosymbiotic bivalves: a systematic revision of worldwide Anodontia (Mollusca: Bivalvia: Lucinidae). Systematics and Biodiversity 3: 281-338.","TAYLOR J. D. & GLOVER E. A. 2006. - Lucinidae - the most diverse group of chemosymbiotic molluscs. Zoological Journal of the Linnean Society 148: 421-438.","TENISON- WOODS J. E. 1876. - Description of new Tasmanian shells. Papers and Proceedings of the Royal Society of Tasmania 1875: 2-30.","THIELE J. 1930. - Gastropoda und Bivalvia, in MICHAELSON W. & HARTMEYER R. (eds), Die Fauna Sudwestaustraliens. Gustav Fischer, Jena: 561-596.","TOKUNAGA S. 1906. - Fossils from the environs of Tokyo. Journal of the College of Science, Imperial University, Tokyo 21: 1-96.","WILD C., HUETTEL M., KLUETER A., KREMB S. G., RASHEED M.Y.M. & JORGENSON B. B. 2004. - Coral mucus functions as an energy carrier and particle trap in the reef system. Nature 428: 66-70.","WILLIAMS S. T., TAYLOR J. D. & GLOVER E. A. 2004. - Molecular phylogeny of the Lucinoidea","ZORINA I. P. 1978. - [New species of bivalve molluscs (Bivalvia) of the Gulf of Tonkin (South China Sea)]. Trudy Zoological Institut, Leningrad 61: 193-203 (in Russian).","ZUCHSIN M. & OLIVER P.G.2003. - Bivalves and Bivalve Habitats in the Northern Red Sea. The Northern Bay of Safaga (Red Sea, Egypt): an Actuopalaeontological Approach. VI. Bivalvia. Naturhistorisches Museum, Vienna, 304 p."]}

Genus Myrtina n.gen. TYPE SPECIES. — Myrtina porcata n. sp. (here designated). ETYMOLOGY. — Myrtina diminutive of Myrtea. DIAGNOSIS. — Shells small to medium in size, relatively flat, sub-circular, dorsal anterior margin with more or less elevated commarginal lamellae. Sculpture of fine to prominent, closely spaced, commarginal lamellae. Radial ribs absent. Lunule lanceolate to heart-shaped, asymmetric with larger part in right valve. Two cardinal teeth in left valve and single tooth in right valve; indistinct lateral teeth present in both valves. Anterior adductor scar short, detached for about 1/5 of length. Pallial line entire. Shell margin smooth. REMARKS Alucinoma Habe, 1958 is similar in outline to Myrtina n. gen. but the type species, A. soyae Habe, 1958, from Japan, lacks hinge teeth and the thin commarginal lamellae are prominent largely on the posterior and anterior dorsal margins of the shell., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on page 120, DOI: 10.5281/zenodo.5392295

Bretskya scapula n. sp. (Figs 39B; 40; 41) TYPE MATERIAL. — Holotype: 1 sh, L 6.8 mm, H 4.4 mm, T 1.4 mm (BMNH 20050579). Paratypes: from type locality, 1 sh, L 6.8 mm, H 5.5 mm, T (2v) 3.2 mm (BMNH 20050580); 1 sh, L 6.7 mm, H 6.2 mm, T(2v) 3.3 mm (Conchology Inc. Reference Collection, Philippines). — Figured paratypes: from type locality, 1 sh, L 6.3 mm, H 5.6 mm, T 1.6 mm (MNHN); 1 sh, L 5.0 mm, H 3.8 mm, T (2v) 2.2 mm (BMNH 20050580); 1 sh, L 6.8 mm, H 6.1 mm, T (2v) 3.2 mm (BMNH 20050580); 1 sh, L 6.0 mm, H 4.5 mm, T (1v) 1.3 mm (BMNH 20050580); 1 sh, L 4.0 mm, H 3.0 mm, T (2v) 1.9 mm (BMNH 20050580). TYPE LOCALITY. — Philippines, Pipe Point, Pandanan Island, Jetafe, Bohol, 10°10.34’N, 124°05.94’E, 5 m, muddy sand, 12.III.2005, col. P. Poppe. ETYMOLOGY. — Latin scapula, shoulder blade – in reference to the shape of this bivalve. MATERIAL EXAMINED. — Touho. Stn 1249, 20°49’S, 165°19’E, 80-140 m, 1 RV, L 8.5 mm, H 7.7 mm (MNHN). Philippines. MUSORSTOM 3, stn DR 140, 11°43’N, 122°34’E, 93-99 m, 8 v (MNHN). DISTRIBUTION. — Recorded only from Philippines and New Caledonia at depths from 5- 100 m. DESCRIPTION Small, thin-shelled, H to 6.9 mm, L to 8.4 mm, outline irregular elongate ovoid, truncate to sinuate posteriorly, longer than high, H/L 0.68-0.82; highly anteriorly extended, slightly inflated. Umbones prominent, usually in posterior part of shell. Protoconch 160 µm long, PI 85 µm. PII with marked growth increments. Shell sculpture of irregular, thin, low, commarginal lamellae and fine growth increments, shell surface often distorted and plicate. Anterior dorsal margin elongate. Posterior dorsal margin steeply sloping. Lunule narrow, lanceolate. Ligament large, set on elongate resilifer. Hinge with two small, cardinal teeth in left valve and one in right valve, lateral teeth absent. Anterior adductor muscle scar short, reniform, detached from pallial line for about 1/3 of length. Pallial line entire. Shell margin smooth. REMARKS The material from the Philippines, on which this new species and genus is based, consists of seven livecollected shells. The characters are highly distinctive and unlike any other known lucinid. Although we have only a single right valve of this species from New Caledonia, it matches the characters of the type specimens., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on pages 170-172, DOI: 10.5281/zenodo.5392295

Genus Pillucina Pilsbry, 1921 Pillucina Pilsbry, 1921: 382. Type species: Pillucina spaldingi Pilsbry, 1921 (junior subjective synonym of P. hawaiiensis (Smith, 1885)) (original designation). Sydlorina Iredale, 1930: 390. Type species: Sydlorina symbolica Iredale, 1930 (original designation). DIAGNOSIS. — Shells small (H to 14 mm), inflated, sculpture of fine to broad radial ribs that often bifurcate, crossed by fine, low, commarginal lamellae. Sculpture usually more prominent on anterior and posterior parts of shell. Hinge with two cardinal teeth in left valve and a single cardinal tooth in right valve. Posterior lateral tooth present in both valves, anterior lateral tooth present or absent. Ligament internal, located on elongate resilifer that widens to the posterior.Anterior adductor muscle scar short and detached from pallial line for about 1/4-1/2 of length. Inner shell margin finely to coarsely crenulate., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on page 158, DOI: 10.5281/zenodo.5392295, {"references":["PILSBRY H. A. 1921. - Marine Mollusks of Hawaii - XIV, XV. Proceedings of the Academy of Natural Sciences of Philadelphia 72: 360 - 382.","SMITH E. A. 1885. - Report on the Lamellibranchiata collected by H. M. S. Challenger during the years 1873 - 76. Report of the Scientific Results of the Voyage of H. M. S. Challenger 1873 - 76 13: 1 - 341.","IREDALE T. 1930. - More notes on the marine Mollusca of New South Wales. Records of the Australian Museum 17: 384 - 407."]}

Solelucina koumacia n. sp. (Figs 6E; 10; 11) TYPE MATERIAL. — Holotype: 1 sh, L 14 mm, H 9.9 mm, T 3.2 mm (MNHN). Paratypes: New Caledonia, Baie de St Vincent, stn 163, 22°12’S, 166°08’E, 15 m, 3 sh, L 17.1 mm, H 11.2 mm; L 21.0 mm, H 15.2 mm; L 14.4 mm, H 9.6 mm (MNHN). — New Caledonia, Touho, Grand Récif Mengalia, 20°45.2’S, 165°16.3’E, intertidal, stn 1245, 1 sh, L 17.4 mm, H 12.0 mm (MNHN). — Loyalty Islands, Lifou, Baie du Santal, stn 1463, 20°55.05’S, 167°03.35’E, 20-30 m, 5 sh, L 15.4 mm, H 10.6 mm; L 13.5 mm, H 9.0 mm; L 11.8 mm, H 8.5 mm; L 12.3 mm, H 9.3 mm; L 9.3 mm, H 6.8 mm (BMNH 20050571). TYPE LOCALITY. — New Caledonia, stn 98, Île Ouen, Baie du Prony, 22°36’S, 166°32’E, 15 m. ETYMOLOGY. — Koumacia, derived from the locality Koumac, New Caledonia. MATERIAL EXAMINED. — Koumac. 8 stn, 0-120 m, 35 v, 4 live. Touho. 1 stn, 0 m, 1 live. Lifou. 10 stn, 4-45 m, 147 v, 15 live. Chesterfield Islands. CORAIL 2, stn DW 04, 20°52’S, 161°37’E, 64 m, 1 v. — Stn DW 28, 20°28’S, 160°56’E, 78 m, 1 v. — Stn DW 32, 19°25’S, 158°49’E, 55 m, 1 sh. — Stn DW 60, 19°15’S, 158°57’E, 45 m, 3 v. — Stn DW 85, 19°12’S, 158°57’E, 32 m, 1 v. — Stn DW 87, 19°06’S, 158°60’E, 31 m, 1 sh. — Stn DW 91, 19°03’S, 158°55’E, 43 m, 2 v. — Stn DW 146, 19°47’S, 158°16’E, 44 m, 1 sh, 1 v. — Stn DW 147, 19°37’S, 158°14’E, 25 m, 2 v. — Stn DW 160, 19°46’S, 158°23’E, 35-41 m, 1 sh, 1 v. Other New Caledonia. LAGON, stn 293, Grand Récif du Sud, 22°42’S, 166°41’E, 20 m, 4 v. — Stn 341, 22°49’S, 166°46’E, 19 m, 1 v. — Stn 544, 22°51’S, 166°49’E, 25 m, 1 sh, 1 v. — Stn 98, Île Ouen, Baie du Prony, 22°36’S, 166°32’E, 15 m, 2 v. — Stn 163, Baie de St Vincent, 22°12’S, 166°08’E, 15 m, 3 sh. — Stn 218, 15 m, 21°52’S, 165°46’E, 1 sh. — Stn 49, secteur de Nouméa, 22°19’S, 166°14’E, 10 m, 1 sh. — Stn 1015, secteur de Poum, 20°10’S, 163°52’E, 25 m, 1 sh. HABITAT. — Intertidal to 50 m, sandy reef platforms and seagrass. DISTRIBUTION. — Western Pacific: Chesterfield Bank, New Caledonia, Loyalty Islands. DESCRIPTION Shell medium size H to 18.8 mm, L to 23.3 mm, elongate oval in outline, longer than high H/L 0.7, posterior margin blunt, anterior margin rounded, moderately inflated T/L 0.2. Posterior dorsal margin straight, long, sloping, with slightly extended dorsal margin. Anterior dorsal margin shorter, rounded. Posterior dorsal area demarcated by one or two low ridges. Umbones low, located anterior of centre. Periostracum, thin, fibrous, buff coloured. Juvenile shell to around 2.5 mm shell height with 11 or 12 thin, low, widely, but regularly spaced, commarginal lamellae (Fig. 11A). Protoconch flat (170 µm), PI large, PII a narrow rim. Adult shell smooth, glossy, with fine growth increments. Shell colour creamy white, often with up to 10 prominent, pink-orange, radial rays, that are solid or interrupted (Fig. 10). Lunule elongate, lanceolate, usually symmetrical. Escutcheon prominent, long, deep. Lunule and escutcheon areas glossy and often coloured dull orange. Ligament external, short. Hinge plate thin, RV with single cardinal, and a socket, anterior lateral low elongate, posterior lateral a low ridge. LV with single cardinal, lateral teeth absent. Anterior adductor muscle scar short, reniform, detached from pallial line for 1/4 of length. Anterior pedal retractor scar distinct. Posterior adductor scar short, reniform. Pallial line entire, broad. Shell outside pallial line glossy white to pale orange. Shell margin smooth. Shell interior glossy, sometimes slightly ridged and thickened, white to pale yellow. Anatomy Observations on a rehydrated body show this bivalve has typical lucinid features – ctenidia with thick single demibranchs only, highly reduced labial palps, a large foot and two posterior apertures. The exhalant aperture has a short eversible tube and there is a short length of mantle fusion ventral to inhalant aperture. REMARKS Myrtea pseudocorbis Nicklés, 1952, from West Africa, has a similar elongate shell, hinge teeth and adductor muscle but differs in the prominent concentric lamellae over all the shell.

Gonimyrtea fidelis n. sp. (Figs 12 C-F; 13B) TYPE MATERIAL. — Holotype: 1 LV, L 10.1 mm, H 10.4 mm, T 3.7 mm, (MNHN). Paratype: from type locality, 1 RV, L 8.3 mm, H 8.2 mm, T 2.5 mm (MNHN). TYPE LOCALITY. — Loyalty Islands, MUSORSTOM 60, stn DW 441, 20°54’S, 167°17’E, 80 m. ETYMOLOGY. — Latin fidelis, “to have faith in”, a reference to the type locality of Loyalty Ridge. MATERIAL EXAMINED. — Koumac. 2 stn, 10-60 m, 5 v. Lifou. 4 stn, 10-120 m, 5 v. DESCRIPTION Shells small,H to 10.4mm,L to 10.1 mm, subcircular, inflated (T/L 0.37), umbones prominent, central. Sculpture of closely spaced,low, regular,commarginal lamellae.Lunule lanceolate, slightly impressed. Ligament short, shallowly inset. Hinge: RV with two cardinal teeth, the posterior large and triangular, the anterior a small narrow ridge; anterior lateral tooth present but indistinct. LV with two cardinal teeth, the anterior larger, posterior a narrow ridge; small anterior lateral socket. Anterior adductor scar short, detached from pallial line for 1/4 of length. Traces of adductor scars marked by radial ridges on interior of shell. Posterior scar ovate. Pallial line faint, entire. Shell edge smooth but with marginal groove., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on page 130, DOI: 10.5281/zenodo.5392295

Parvidontia laevis n. sp. (Figs 38; 39A) TYPE MATERIAL. — Holotype: 1 LV, L 5.8 mm, H 5.5 mm, T 1.8 mm (MNHN). Paratypes: New Caledonia, secteur de Canala, stn 729, coarse shell sand, 21°19’S, 165°54’E, 42-45 m, 2 LV,1 RV, L 6.5 mm, H 5.7 mm, T 1.9 mm; L 5.8 mm, H 1.5 mm; L 3.2 mm, H 3.0 mm (MNHN). — New Caledonia, Secteur de Belep, stn 1196, 19°33’S, 163°21’E, 30 m, 1 LV, L 10.7 mm, H 10.9 mm, T 3.4 mm (BMNH 20050578). TYPE LOCALITY. — New Caledonia, Touho, stn 1260, 20°44’S, 165°14’E, shell sand, 49- 59 m. ETYMOLOGY. — Latin laevis, smooth. MATERIAL EXAMINED. — Touho. 1 stn, 49-59 m, 1 v. DESCRIPTION Small, H to 10.9 mm, L to 10.7 mm, thin-shelled, subcircular, umbones prominent, external surface smooth, except for fine commarginal threads. Protoconch large, 210 µm, smooth, with a few marginal growth increments. Ligament external, very short. Hinge narrow, teeth small,LV with two cardinal teeth of which anterior is larger and projecting; RV with 2 cardinals of which anterior is very small. Lateral teeth absent. Anterior adductor muscle scar narrow, detached for 1/2 length.Pallial line entire, broad, with dorsal extensions. Inner shell margin smooth. REMARKS Externally, the smooth shell, with low commarginal lamellae, of P. laevis n. sp. resembles Leucosphaera diaphana n. sp. (p. 118) but it can easily be distinguished by the presence of cardinal teeth., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on page 168, DOI: 10.5281/zenodo.5392295

Liralucina vaubani n. sp. (Figs 26D; 29) TYPE MATERIAL. — Holotype: 1 sh, L 3.2 mm, H 3.1 mm, T 1.5 mm (MNHN). Paratypes: from type locality, 3 sh and 1 v (BMNH 20050575). —Figured paratypes: from type locality, 2 v, L 2.5 mm, H 2.2 mm; L 2.6 mm, H 2.3 mm (MNHN). TYPE LOCALITY. — New Caledonia, MUSORSTOM 4, stn DW 149, 19°08’S, 163°23’E, 155 m. ETYMOLOGY. — After NO Vauban, name of the ship that collected the material. DISTRIBUTION. — Known only from New Caledonia. DESCRIPTION Shell small, white, H to 3.1 mm, L to 3.2 mm, subcircular (H/L 0.97), inflated. Umbones prominent. Sculpture of 22-24 radial ribs. Ribs rounded in profile, occasionally dividing, crossed by regularly spaced, fine commarginal lamellae, ribs are less prominent to posterior. Juvenile shell to c. 500 µm with commarginal lamellae only. Protoconch large (160 µm), rounded, PI 90 µm, smooth, PII with fine growth increments. Lunule long, wide and slightly asymmetric,right part larger.Ligament short, slightly inset. Hinge: LV with two cardinal teeth and large anterior lateral and posterior lateral teeth and sockets. RV with one cardinal tooth and prominent anterior and posterior lateral teeth. Anterior adductor scar short, rounded, slightly detached from pallial line; posterior scar oval. Pallial line continuous. Inner shell margin coarsely crenulate. REMARKS See comparison with L. sperabilis n. comb. above., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on page 152, DOI: 10.5281/zenodo.5392295

Genus Poumea n. gen. TYPE SPECIES. — Poumea coselia n. sp. (here designated). ETYMOLOGY. — Derived from Poum, the type locality of Poumea coselia n. sp. DIAGNOSIS. — Shell small, subcircular, umbones prominent. Sculpture of regularly spaced, thin, commarginal lamellae. Lunule asymmetric, larger in left valve. Two cardinal teeth in each valve. Anterior lateral teeth present, posterior laterals absent. Anterior adductor scar long, detached from pallial line for 3/4 of length. REMARKS Although superficially resembling Myrtea and Notomyrtea, this new genus differs in having two cardinal teeth in each valve and a much longer anterior adductor muscle scar. Also, it lacks the radial riblets between the commarginal lamellae of Notomyrtea species (see Fig. 5)., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on page 124, DOI: 10.5281/zenodo.5392295

Liralucina craticula n. sp. (Figs 26B; 27) TYPE MATERIAL. — Holotype:1 RV,L 3.8 mm, H 3.3 mm, T 1.1 mm (MNHN). Paratypes: from type locality, 43 v and 3 juvenile shells (largest L 4.5 mm, H 3.8 mm, T 1.3 mm) (MNHN). — Figured paratypes: from type locality, 1 LV, L 3.8 mm, H 3.2 mm, T 1.0 mm; 1 LV, L 3.5 mm, H 3.0 mm, T 1.0 mm (MNHN); 1 LV, L 3.5 mm, H 3.2 mm, T 1.1mm (BMNH 20050574); 1 RV, L 3.4 mm, H 2.9 mm, T 1.0 mm (BMNH 20050574). ETYMOLOGY. — Latin cratis, wickerwork or hurdle, reference to the form of sculpture. TYPE LOCALITY. — New Caledonia, Baie de Touho, stn 1250, 20°46.7’S, 165°13.7’E, 3- 6 m. MATERIAL EXAMINED. — Touho. 6 stn, 0-8 m, 120 v, 2 live. DISTRIBUTION. — Known only from New Caledonia. DESCRIPTION Shell white, small, H to 3.8 mm, L to 4.5 mm, subovate, anteriorly extended, longer than high (H/L 0.86), inequilateral, anterior end longer, moderately inflated (T/L 0.29) umbones elevated. Sculpture of numerous fine, radial ribs (35-38), rounded in profile, variable in thickness, occasionally dividing, crossed by fine, widely spaced commarginal threads.Radial ribs become indistinct on posterior dorsal area.In juvenile shells radial ribs absent or faint (Fig. 27G).Protoconch large (140 µm); PI flat, smooth,PII a very narrow rim. Lunule large, symmetrical. Ligament short, slightly inset. RV with a single cardinal tooth and anterior lateral and posterior lateral teeth and sockets.LV with two small cardinal teeth, long anterior lateral socket and a posterior tooth and socket. Anterior adductor scar short, detached from pallial line for about 1/5 of length. Posterior scar ovate. Pallial line continuous. Shell margin finely crenulate, indistinct near anterior and absent along posterior margin. REMARKS Liralucina craticula n. sp. is similar to L. lifouina n. sp. but has fewer radial ribs with broader interspaces, more widely spaced commarginal lamellae and a longer,more incised lunule. The protoconch of L. craticula n. sp. has a large, smooth PI and very narrow PII compared with L. lifouina n. sp. that has a convex protoconch with a broad PII with growth increments., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on pages 150-151, DOI: 10.5281/zenodo.5392295, {"references":["HEDLEY C. 1909. - Mollusca from the Hope Islands, North Queensland. Proceedings of the Linnean Society of New South Wales 34: 420 - 466."]}

Genus Solelucina n. gen. TYPE SPECIES. — Solelucina koumacia n. sp. (here designated). DIAGNOSIS. — Shells small, H to 19 mm, L to 23 mm, with elongate oval outline, blunt posterior shell margin. Exterior smooth, juvenile shell with prominent commarginal lamellae. Hinge with single cardinal tooth in each valve, RV with low, ridge-like, anterior and posterior lateral teeth, lateral teeth absent in LV. Anterior adductor muscle scar short, reniform in outline, detached from pallial line for only 1/5 of length. Inner shell margin smooth. Shell colour distinctive – cream to white, often with red to orange rays. ETYMOLOGY. — Latin sol, sun, a reference to sunray-like, red, radiating rays on the shell. REMARKS With the elongate, smooth shell and pink/orange radial colour pattern, Solelucina n. gen. is a very unusual lucinid with a superficial resemblance to some species of Tellinidae. However, it shares a number of characters with Myrtea and Notomyrtea, including the elongate outline and similar hinge dentition. Although the exterior shells of adult Solelucina n. gen. are smooth, the commarginal lamellae of the juvenile shells are similar to those of Myrtea. The short, reniform, anterior adductor muscle scar and the glossy shell interior are also similar., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on page 124, DOI: 10.5281/zenodo.5392295

Genus Liralucina n. gen. TYPE SPECIES. — Phacoides sperabilis Hedley, 1909 (here designated). INCLUDED SPECIES. — L. sperabilis n. comb., L. craticula n. sp., L. lifouina n. sp. and L. vaubani n. sp. DIAGNOSIS. — Shells small (lira, ridge, in reference to the radial ribs. REMARKS Many small species of lucinids with fine commarginal lamellae and radial ribs have been referred to Parvilucina Dall, 1901 (type species: Lucina tenuisculpta Carpenter, 1864 from the temperate northeast Pacific), but we think that several distinct taxa have been included within this concept. Parvilucina tenuisculpta differs from Liralucina n. gen. in having a much smoother shell with numerous, indistinct, fine radial ribs, a longer ligament, relatively larger teeth, a longer anterior adductor scar and a finely crenulate inner shell margin (see Hickman [1994] and Coan et al. [2000] for illustrations of Parvilucina species from NE Pacific). Liralucina sperabilis (Hedley, 1909) n. comb. (Figs 25; 26A) Phacoides sperabilis Hedley, 1909: 427, pl. 37, fig. 18. Linga (Bellucina) sperabilis – Lamprell & Healy 1998: 254, fig. 777 (not fig. 778 as given). Parvilucina cf. sperabilis – Zuschin & Oliver 2003: 108, pl. 25, figs 7-11. TYPE MATERIAL. — Holotype: 1 LV, L 3.3 mm, H 3.1 mm (AMS C.27565). Probable paratypes: from type locality, 4 v (BMNH 1910.928.72-6). TYPE LOCALITY. — Hope Islands, Queensland, Australia, 5-10 fathoms. MATERIAL EXAMINED. — Koumac. 14 stn, 0-120 m, 268 v. Touho. 12 stn, 6-60 m, 282 v, 16 live. Chesterfield Islands. CHALCAL 1, stn DC 20, 19°12’S, 158°42’E, 67 m. — Stn DC 21, 19°18’S, 158°43’E, 73 m. — Stn DC 27, 19°17’S, 158°34’E, 67 m. New Caledonia. LAGON, stn 25, secteur de Nouméa, 22°21’S, 166°27’E, 28 m, 1 v. — Stn 41, 22°19’S, 166°16’E, 28-46 m, 1 v. — Stn 42, 22°17’S, 166°17’E, 25 m, 2 v. — Stn 119, Île Ouen, Baie du Prony, 22°28’S, 166°46’E, 20 m, 1 v. — Stn 439, Atoll de Huon, 18°07’S, 162°55’E, 39 m, 28 v. — Stn 440, 18°05’S, 162°55’E, 39 m, 1 v. — Stn 503, 19°12’S, 163°29’E, 64 m, 2 v. — Stn 517, 19°09’S, 163°35’E, 42 m, 1 v. — Stn 575, Grand Récif Sud, 22°55’S, 166°59’E, 62 m, 1 v. — Stn 729, secteur de Canala, 21°19’S, 165°54’E, 42 m, 30 v. — Stn 830, secteur de Poindimie, 20°49’S, 165°19’E, 105 m, 2 v. — Stn 898, secteur de Puebo, 20°14’S, 164°27’E, 22 m, 1 v. — Stn 973, secteur de Poum, 20°24’S, 163°60’E, 27 m, 1 v. — Stn 1082, secteur des Belep, 19°55’S, 163°45’E, 34 m, 1 v. — Stn 1085, 19°50’S, 163°53’E, 33 m, 3 v. — Stn 1091, 19°48’S, 163°48’E, 38 m, 6 v. — Stn 1092, 19°50’S, 163°46’E, 37 m, 4 v. — Stn 1093, 19°53’S, 163°44’E, 37 m, 1 v. — Stn 1111, 19°42’S, 163°42’E, 38 m, 1 v. — Stn 1114, 19°38’S, 163°50’E, 43 m, 1 v. — Stn 1129, 19°29’S, 163°49’E, 40 m, 1 v. — Stn 1205, 19°42’S, 163°26’E, 38 m, 1 v. — Stn 1214, 19°50’S, 163°37’E, 29 m, 1 v. — Stn 1216, 19°50’S, 163°38’E, 30 m, 1 v. BATHUS 1, stn DW 674, East coast, 20°49’S, 165°19’E, 105 m, 10 v. DISTRIBUTION. — Red Sea (Zuchsin & Oliver 2003) to northern Australia and New Caledonia. DESCRIPTION Small, white, H to 4.5 mm, L to 4.3 mm, subcircular (H/L 1.0), inflated (T/L 0.41).Umbones prominent. Sculpture of 18-20 radial ribs with broad interspaces. Ribs rounded in profile, occasionally dividing, crossed by regularly-spaced, fine commarginal lamellae; ribs less prominent posteriorly. Juvenile shell to 500 µm with commarginal lamellae only. Protoconch large (140 µm), rounded, PI (c. 90 µm) smooth, PII with faint growth increments. Lunule long, wide, and slightly asymmetric, right part larger. Ligament short, slightly inset. Hinge: LV with two cardinal teeth and large anterior and posterior lateral teeth and sockets; RV with one cardinal tooth and anterior and posterior lateral teeth. Anterior adductor scar short, rounded, slightly detached from pallial line; posterior scar oval. Pallial line continuous. Inner shell margin coarsely crenulate. REMARKS Lucina pulchella Lynge, 1909 (p. 173, 174, pl. III, figs 13-15) (see also Robba et al. 2002: 78, fig. 5), described from the Gulf of Thailand, is similar but the figure shows clearly dividing radial ribs. Liralucina sperabilis n. comb. is most similar to L. vaubani n. sp. (see below) but differs in having fewer, more prominent and widely spaced radial ribs and the inner shell margin is much more coarsely crenulate. Liralucina craticula n. sp. and L. lifouina n. sp. (below) differ in having far more fine, closely spaced, radial ribs., Published as part of Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, pp. 109-181 in Zoosystema 29 (1) on pages 147-150, DOI: 10.5281/zenodo.5392295, {"references":["HEDLEY C. 1909. - Mollusca from the Hope Islands, North Queensland. Proceedings of the Linnean Society of New South Wales 34: 420 - 466.","DALL W. H. 1901. - Synopsis of the Lucinacea and of the American species. Proceedings of the United States National Museum 23: 779 - 833.","HICKMAN C. S. 1994. - The genus Parvilucina in the Eastern Pacific: making evolutionary sense of a chemosymbiotic species complex. Veliger 37: 43 - 61.","COAN E. V., SCOTT P. V. & BERNARD F. R. 2000. - Bivalve Seashells of Western North America. Santa Barbara Museum of Natural History, Santa Barbara, 764 p.","DESHAYES M. G. P. 1832. - Encyclopedie methodique. Histoire naturelle des vers, par Bruguiere et de Lamarck. Volume 2 (2). Agasse, Paris: 145 - 584.","REEVE L. A. 1850. - Monograph of the genus Lucina. Conchologica Iconica vol. 6. Reeve, Benham & Reeve, London, 11 pls.","LAMPRELL K. & HEALY J. 1998. - Bivalves of Australia. Volume 2. Backhuys Publishers, Leiden, 288 p.","ZUCHSIN M. & OLIVER P. G. 2003. - Bivalves and Bivalve Habitats in the Northern Red Sea. The Northern Bay of Safaga (Red Sea, Egypt): an Actuopalaeontological Approach. VI. Bivalvia. Naturhistorisches Museum, Vienna, 304 p.","LYNGE H. 1909. - The Danish Expedition to Siam 1899 - 1900. IV. Marine Lamellibranchiata. Kongelige Danske Videnskabernes Selskabs Skrifter 5: 101 - 299.","ROBBA E., GERONIMO I. D., CHAIMANEE N., NEGRI M. P. & SANFILIPPO R. 2002. - Holocene and Recent shallow soft-bottom mollusks from the northern Gulf of Thailand area: Bivalvia. Bolletino Malacologico 38: 49 - 132."]}