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The abyssal seafloor in the Clarion-Clipperton Zone (CCZ) in the NE Pacific hosts the largest abundance of polymetallic nodules in the deep sea and is being targeted as an area for potential deep-sea mining. During nodule mining, seafloor sediment will be brought into suspension by mining equipment, resulting in the formation of sediment plumes, which will affect benthic and pelagic life not naturally adapted to any major sediment transport and deposition events. To improve our understanding of sediment plume dispersion and to support the development of plume dispersion models in this specific deep-sea area, we conducted a small-scale, 12-hour disturbance experiment in the German exploration contract area in the CCZ using a chain dredge. Sediment plume dispersion and deposition was monitored using an array of optical and acoustic turbidity sensors and current meters placed on platforms on the seafloor, and by visual inspection of the seafloor before and after dredge deployment. We found that seafloor imagery could be used to qualitatively visualise the redeposited sediment up to a distance of 100 m from the source, and that sensors recording optical and acoustic backscatter are sensitive and adequate tools to monitor the horizontal and vertical dispersion of the generated sediment plume. Optical backscatter signals could be converted into absolute mass concentration of suspended sediment to provide quantitative data on sediment dispersion. Vertical profiles of acoustic backscatter recorded by current profilers provided qualitative insight into the vertical extent of the sediment plume. Our monitoring setup proved to be very useful for the monitoring of this small-scale experiment and can be seen as an exemplary strategy for monitoring studies of future, upscaled mining trials. We recommend that such larger trials include the use of AUVs for repeated seafloor imaging and water column plume mapping (optical and acoustical), as well as the use of in-situ particle size sensors and/or particle cameras to better constrain the effect of suspended particle aggregation on optical and acoustic backscatter signals.

There is a strong economic interest in commercial deep‐sea mining of polymetallic nodules and therefore a need to define suitable preservation zones in the abyssal plain of the Clarion Clipperton Fracture Zone (CCZ). However, besides ship‐based multibeam data, only sparse continuous environmental information is available over large geographic scales. We test the potential of modelling meiofauna abundance and diversity on high taxonomic level on large geographic scale using a random forest approach. Ship‐based multibeam bathymetry and backscatter signal are the only sources for 11 predictor variables, as well as the modelled abundance of polymetallic nodules on the seafloor. Continuous meiofauna predictions have been combined with all available environmental variables and classified into classes representing abyssal habitats using k‐means clustering. Results show that ship‐based, multibeam‐derived predictors can be used to calculate predictive models for meiofauna distribution on a large geographic scale. Predicted distribution varies between the different meiofauna response variables. To evaluate predictions, random forest regressions were additionally computed with 1,000 replicates, integrating varying numbers of sampling positions and parallel samples per site. Higher numbers of parallel samples are especially useful to smoothen the influence of the remarkable variability of meiofauna distribution on a small scale. However, a high number of sampling positions is even more important, integrating a greater amount of natural variability of environmental conditions into the model. Synthesis and applications. Polymetallic nodule exploration contractors are required to define potential mining and preservation zones within their licence area. The biodiversity and the environment of preservation zones should be representative of the sites that will be impacted by mining. Our predicted distributions of meiofauna and the derived habitat maps are an essential first step to enable the identification of areas with similar ecological conditions. In this way, it is possible to define preservation zones not only based on expert opinion and environmental proxies but also integrating evidence from the distribution of benthic communities.

OEDICERINA CLAUDEI JAżDżEWSKA, SP. NOV. (FIGS 19���23) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: D1CB7EA5-FC38-406F-A101-BC5EBE7E1762. Type material Holotype: Juvenile, 4.5 mm, body remnants and two slides with appendages, SMF-56781, St. AKL-71-1-9, 46��05.037��� N, 146��00.465��� E- 46��08.727��� N, 146��00.227��� E; 3307��� 3307 m, 10 July 2015, leg. Marina V. Malyutina. The registered type material is deposited in the Senckenberg Museum (Frankfurt, Germany). Type locality: Sea of Okhotsk, St. AKL-71-1-9, 46��05.037��� N, 146��00.465��� E- 46��08.727��� N, 146��00.227��� E; 3307��� 3307 m. Etymology: The species is named for Dr. Claude De Broyer, a great friend and one of the first author���s scientific mentors and renowned specialist in amphipod taxonomy, diversity and ecology. Description: Based on juvenile, 4.5 mm, St. AKL-71-1-9. Head (Fig. 19): longer than deep, longer than pereonites 1���4 combined; no eyes or ocular pigment visible; rostrum deflexed, the angle between head dorsal margin and rostrum margin almost 90 ��, rostrum reaching the end of first article of peduncle of antenna 1; interantennal lobe indistinct. Antenna 1 (Fig. 20): length ratios of peduncle articles 1���3 1:0.7:0.4, peduncle article 1 laterally acutely produced; flagellum 5-articulate, first article as long as article 3 of peduncle; accessory flagellum 1-articulate, minute, slender, length 0.2 �� first flagellum article; peduncle and flagellum sparsely setose. Antenna 2 (Fig. 20, considerably damaged): length of peduncle article 4 1.5 �� article 5. Upper lip (labrum) (Fig. 20): wider than long, rounded apically, with fine setules laterally. Mandible (Fig. 20): incisor margins with five teeth; left lacinia mobilis four-cusped; right lacinia mobilis narrower slightly cuspidate; accessory spine rows with five serrate setae; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 1.1 �� longer than article 3, with four posterodistal setae, article 3 slightly tapering distally, anterior margin with two setae, posterior margin with two setae, three setae at apex. Lower lip (Fig. 20): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 20): inner plate oval, with two distal setae; outer plate with eight acute setal-teeth (three with bifurcate tips); palp 2-articulate, longer than outer plate, slender, rounded apically, article 1 short, length 0.2 �� article 2, article 2 with five or six apical/subapical setae and one long, lateral setae. Maxilla 2 (Fig. 20): left���plates subequal in length, right���inner plate shorter than outer, inner plate width about 1.1 �� outer, with setae and spines apically and subapically, fine setules along inner margin; outer plate rounded with apical spines and setae, outer margin with fine setules. Maxilliped (Fig. 21): inner plate subrectangular, reaching about 0.3 �� basal article of palp, apical margin with six slender spines; outer plate slender and slightly curved, long, reaching 0.4 �� length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; article 1 tapering distally; article 2 triangular, widest at 0.6 �� length, setose medially; article 3 expanded mediodistally, slightly produced along article 4; article 4 strong, slightly curved; length ratios of articles 1���4 1:1.9:0.7:1.3. Pereon. Pereonite 1 (Fig. 19) twice as long as pereonite 2, pereonite 3 longer than 2, pereonites 4���5 subequal in length, longer than pereonites 1���3, pereonites 6���7 of the same length, longer than all preceding segments. Gnathopod 1 (Figs 19, 21): coxa subtriangular, anterodistal corner bluntly rounded, posterodistal corner rectangular, ventral margin naked, width to depth ratio 1:0.8; basis straight, slightly expanded distally, distal half of anterior margin with row of long setae, sparse setae on the surface; merus, posterodistal lobe subquadrate, moderately setose; carpus strongly expanded, anterior margin with five setae along distal half, posterior lobe subacute with setae along posterior and distal margins; propodus subchelate, triangular, strongly widening distally, anterior margin moderately setose, palm longer than hind margin, transverse, strongly convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, longer than palm. Gnathopod 2 (Figs 19, 21): coxa narrow, slightly tapering distally, width 0.4 �� depth, apex rounded, ventral margin naked; basis straight, 16 long setae forming circular patch anterodistally, single moderately long, delicately plumose seta at posterior margin; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with four setae (some delicately plumose), posterodistal lobe subacute, extending palmar corner of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus shorter than carpus, subchelate, triangular, strongly widening distally, anterior margin with eight long setae regularly placed, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, slightly longer than palm. Pereopod 3 (Figs 19, 22): coxa subrectangular, wider and deeper than coxa 2, ventral margin naked; basis shorter than coxa, narrow, length 3.1 �� width, anterior and posterior margins with some long, delicately plumose setae; merus expanded distally, one group of setae anterodistally and two groups of setae posteriorly; carpus broad, length 1.2 �� merus, posteriorly armed with long setae; propodus length 0.8 �� carpus, with six long setae anterodistally and seven long setae along posterior margin; dactylus stout, longer than propodus (1.2 �� propodus). Pereopod 4 (Figs 19, 22): coxa wider than deep, anterior margin strongly convex, extending distally, coxa the widest almost at 2/3 of its depth, ventral margin naked, posteroventral lobe huge, blunt, (width to depth ratio of the lobe 1:0.9), posterior margin deeply excavated; basis long and narrow, length 3.5 �� width, anterior margin with four long, delicately plumose setae, posterior margin with one long, delicately plumose setae, short seta at posterodistal corner; merus expanded, a few setae at anterior margin, one short seta at posterior margin, group of long setae at posterodistal corner; carpus expanded, length 0.8 �� merus, five setae at anterodistal corner, posterior margin armed with 11 long and moderately long setae; propodus narrow, length 0.5 �� carpus, moderately setose at anterior and posterior margins; dactylus stout, longer than propodus (1.9 �� propodus). Pereopod 5 (Fig. 22): right���coxa about as deep as coxa 4, bilobed, posterior lobe expanded ventrally, ventral margin straight, naked, anterior lobe 0.5 �� depth of posterior lobe; basis narrow, length 4.1 �� width, five long, delicately plumose setae at anterior margin; merus as long as basis, with three groups of moderately long plumose setae along anterior margin, seven setae at anterodistal corner, two setae at posterior margin and a group of four setae at posterodistal corner; carpusdactylus broken off; left���coxa about as deep as coxa 4, bilobed, posterior lobe partially damaged; basis narrow, length 2.5 �� width, two long, delicately plumose setae at anterior margin, two long setae at the surface (one delicately plumose); merus 1.1 �� basis, with three groups of moderately long setae along anterior margin, four setae at anterodistal corner, two setae at posterior margin; carpus length 0.5 �� merus, with five setae anterodistally; propodus length 1.6 �� carpus length, with three setae anterodistally; dactylus stout, longer than propodus (1.2 �� propodus length). Pereopod 6 (Fig. 22): coxa bilobed but anterior lobe very small, posterior lobe long, distal margin slightly convex; basis narrow, length 3.9 �� width, anterior margin with seven long, delicately plumose setae along distal half, posterior margin with five long, delicately plumose setae along distal half; merus length 0.7 �� basis, three rows of setae anteriorly, two rows of setae posteriorly; carpusdactylus broken off. Pereopod 7 (Fig. 22): coxa wider than deep, rounded posteriorly; basis ovate, length 1.5 �� width, widest in the mid-length, tapering distally, anterior margin strongly convex, two short spines at anterodistal corner, posterior margin slightly oblique in distal half, smooth, posterodistal lobe nearly as long as ischium; merus length 1.2 �� basis with groups of setae both anteriorly and posteriorly (some setae broken); carpus-dactylus broken off. Pleon. Pleonite 1 (Fig. 19) produced posteriorly, pleonites 2���3 with distinct mid-dorsal, posteriorly directed teeth. Epimera: 1 and 3 evenly rounded, epimeron 2 posterior margin convex, posterodistal corner subquadrate. Pleopods [pleopod 2 (Fig. 23)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 19) longest; urosomite 3 longer than 2. Uropods (Fig. 23): Uropod 1: peduncle length 1.1 �� inner ramus, margins with some short setae; inner ramus 1.4 �� length of outer ramus, rami with sparse setae. Uropod 2: shorter than uropod 1, peduncle length 0.9 �� inner ramus, with some short setae; inner ramus 1.2 �� length of outer ramus, rami with sparse setae. Uropod 3: peduncle short, peduncle length 0.4 �� inner ramus; inner ramus with short spines along distal half of lateral margins; outer ramus damaged. Telson: (Fig. 23) short, length 1.7 �� width, cleft 40%, lobes subacute, widely diverging, notched subapically, tips unequal in size (inner longer than outer), single seta placed in the notch, single dorsolateral seta on the surface. Sexual dimorphism: No sexual or size-dependent variation observed as the individual is unique. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype juvenile of O. claudei (SMF-56781, GenBank accession number MW 377945) is designed as a hologenophore of all obtained sequences. The species has received also a Barcode Index Number from BOLD: AEA4699 (dx.doi. org/10.5883/ BOLD: AEA 4699). Distribution: Sea of Okhotsk (Fig. 25), 3307 m. MOLECULAR INVESTIGATION Each of the morphologically recognized species received a unique Barcode Index Number. Across all species, the intraspecific diversity calculated on haplotypes is low, ranging from 0.002 (O. lesci) to 0.005 (O. henrici) for both K2P and p -distance. Each of the species is represented by three haplotypes (Table 2; Fig. 24B). An exception is O. claudei, as only one individual of this taxon was collected. The distances between the studied taxa varies from 0.059 to 0.238 of p -distance and from 0.061 to 0.289 of K2P (Table 3). The lowest interspecies distances are noted between O. lesci and O. ingolfi, irrespective of the measures applied. The highest values are observed for O. henrici and O. claudei for both measures and for O. henrici and O. ingolfi for p -distance only (Fig. 24A). The haplotype networks show a star-like topology (Fig. 24B). In O. lesci, the central, ancestral and dominant haplotype is present at five stations including the stations situated on both sides of the KKT. In O. henrici and O. teresae, the central, ancestral haplotypes are missing., Published as part of Ja��d��ewska, Anna M., Brandt, Angelika, Arbizu, Pedro Mart��nez & Vink, Annemiek, 2022, Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods, pp. 181-225 in Zoological Journal of the Linnean Society 194 on pages 208-213, DOI: 10.1093/zoolinnean/zlab032, http://zenodo.org/record/5799308, {"references":["Pleijel F, Jondelius U, Norlinder E, Nygren A, Oxelman B, Schander C, Sundberg P, Thollesson M. 2008. Phylogenies without roots? A plea for the use of vouchers in molecular phylogenetic studies. Molecular Phylogenetics and Evolution 48: 369 - 371."]}

Oedicerina sp. 1 Jażdżewska & Mamos, 2019 Type material Holotype: ♀, 13.6 mm, body remnants and two slides with appendages, SMF-56780, SB_10-7E_ Oedi10_2015_1, St. AKL-71-10-7, 46��06.027��� N, 152��14.439��� E- 46��05.827��� N, 152��14.576��� E; 4769���4798 m, 29 July 2015, leg. Marina V. Malyutina. Allotype: ♂, 10.0 mm, one slide with appendages, SMF-56779, 3-9S_Oedi10_2012_1, St. SO-223-3-9, 47��14.66��� N, 154��42.88��� E- 47��14.76��� N, 154��43.03��� E; 4987���4991 m, 5 August 2012, leg. Angelika Brandt. Paratypes: ♀, 9.0 mm, MIMB 40714, 3- 9 S_ Oedi10_2012_2, St. SO-223-3-9, 47��14.66��� N, 154��42.88��� E- 47��14.76��� N, 154��43.03��� E; 4987���4991 m, 5 August 2012, leg. Angelika Brandt. ♂, 9.2 mm, MIMB 40715, SB_10-7S_Oedi10_2015_2, St. AKL- 71- 10- 7, 46�� 06.027��� N, 152 �� 14.439 ��� E- 46��05.827��� N, 152��14.576��� E; 4769���4798 m, 29 July 2015, leg. Marina V. Malyutina. Additional material: One ♀, 8.0 mm, 1-11S_ Oedi_2012_1, St. SO-223-1-11, 43��58.44��� N, 157��18.29��� E- 43��58.61��� N, 157��18.13��� E; 5418���5419 m, 30 July 2012, leg. Angelika Brandt. One juvenile, 3.5 mm, 2-9S_Oedi10_2012_1, St. SO-223-2-9, 46��14.78��� N, 155��32.63��� E- 46��14.92��� N, 155��32.57��� E; 4830���4863 m, 3 August 2012, leg. Angelika Brandt. Two ♀, 8.6���12.0 mm, 15 juveniles, 2.8���7.0 mm, St. SO-223-3-9, 47��14.66��� N, 154��42.88��� E- 47��14.76��� N, 154��43.03��� E; 4987���4991 m, 5 August 2012, leg. Angelika Brandt. One juvenile, 5.1 mm, 9-9S_Oedi10_2012_1, St. SO-223-9-9, 40��34.51��� N, 150��59.92��� E- 40��34.25��� N, 150��59.91��� E; 5399��� 5421 m, 23 August 2012, leg. Angelika Brandt. One juvenile, 3.6 mm, St. SO-223-10-9, 41��12.80��� N, 150��6.162��� E- 41��13.01��� N, 150��05.652��� E; 5245���5262 m, 26 August 2012, leg. Angelika Brandt. One ♂?, 10.0 mm, SB_10-5E_Oedi10_2015_1, 46��07.410��� N, 152��11.292��� E- 46��07.310��� N, 152��11.537��� E; 4681��� 4702 m, 28 July 2015, leg. Marina V. Malyutina. Two ♂, 8.5���10.6 mm, St. AKL-71-10-7, 46��06.027��� N, 152��14.439��� E- 46��05.827��� N, 152��14.576��� E; 4769���4798 m, 29 July 2015, leg. Marina V. Malyutina. One immature ♀, 8.5 mm, 85S_Oedi10_2016_1, SO-250���85, 45��02.26��� N, 151��02.14��� E- 45��01.64��� N, 151��03.68��� E; 4903.4���5265.6 m, 15 September 2016, leg. Angelika Brandt. The registered type material is deposited in the Senckenberg Museum (SMF; Frankfurt, Germany), and in the National Scientific Center of Marine Biology (MIMB; Vladivostok, Russia). All the remaining material is kept in the scientific collection of the Department of Invertebrate Zoology and Hydrobiology, University of Lodz. Type locality: Abyssal plain adjacent to the KKT, St. AKL-71-10-7, 46��06.027��� N, 152��14.439��� E- 46��05.827��� N, 152��14.576��� E; 4769���4798 m. Etymology: The species is named for Krzysztof Leszek (Latin Lescus) Jażdżewski, the first author���s brother. Description: Based on female, 13.6 mm, St. AKL-71- 10-7. Head (Fig. 13): longer than deep, longer than pereonites 1���3 combined; no eyes or ocular pigment visible; rostrum curved but not deflexed, the angle between head dorsal margin and rostrum margin more than 90 ��, rostrum reaching 2/3 of first article of peduncle of antenna 1; interantennal lobe moderate, subtriangular, rounded. Antenna 1 (Fig. 14): shorter than antenna 2; length ratios of peduncle articles 1���3 1:1:0.6, peduncle article 1 dorsally slightly but acutely produced; flagellum 10-articulate; accessory flagellum 1-articulate, minute, slender, half of the length of first flagellum article; peduncular article 1 moderately setose, peduncular articles 2���3 and flagellar articles with sparse setae. Antenna 2 (Fig. 14): peduncle setose (especially article 4); length of article 4 1.5 �� article 5; flagellum broken at fourth article. Upper lip (labrum) (Fig. 14): wider than long, rounded apically, with fine setules laterally. Mandible (Fig. 14): incisor margins with five teeth; left lacinia mobilis five-cusped; right lacinia mobilis narrower slightly cuspidate; accessory spine rows with seven serrate setae; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 equal in length to article 3, swollen proximally, with 17���18 posterodistal setae, article 3 slightly tapering distally, anterior margin with two setae, posterior margin with eight to nine setae, apically with two or three setae. Lower lip (Fig. 14): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 14): inner plate oval, with two distal setae; outer plate with nine acute setalteeth (three with bifurcate tips); palp 2-articulate, longer than outer plate, robust, rounded apically, article 1 short, length 0.3 �� article 2, article 2 with 13 apical/subapical setae and two long, lateral setae, lateral margin with row of small spines. Maxilla 2 (Fig. 14): plates same width, but inner shorter than outer, inner plate slightly tapering distally, with setae and spines apically and subapically, fine setules along inner and outer margins; outer plate rounded with apical spines and setae, with three moderately long apicolateral setae. Maxilliped (Fig. 15) (outer plate on the left side damaged): inner plate subrectangular, reaching about 0.3 �� basal article of palp, apical margin with ten slender spines; outer plate slender and slightly curved, long, reaching 0.4 �� length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; article 1 slightly tapering distally; article 2 triangular, widest at the midpoint, with strong medial setae; article 3 expanded mediodistally, produced along article 4; article 4 strong, slightly curved; length ratios of articles 1���4 1:1.8:0.8:1.3. Pereon. Pereonites 1���6 (Fig. 13) of similar length, pereonite 7 distinctly longer. Gnathopod 1 (Fig. 15): coxa subtriangular, anterodistal corner bluntly rounded, posterodistal corner rectangular, ventral margin setose (some moderately long setae preserved and traces of several broken setae), width to depth ratio 1:0.9; basis straight, weakly expanded, distal half of anterior margin with row of long setae, posterior surface setose; merus, posterodistal lobe rounded, strongly setose; carpus strongly expanded, anterior margin setose along distal half, posterior lobe subacute with setae along posterior margin and distal margin; propodus subchelate, triangular, strongly widening distally, anterior margin with several setae, palm as long as hind margin, transverse, strongly convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with two spines; dactylus curved, as long as palm. Gnathopod 2 (Fig. 15): coxa narrow, slightly tapering distally, width 0.5 �� depth, apex rounded, ventral margin with two setae (one broken); basis straight, six thin setae at inner surface of anterior margin, 28 long setae forming circular patch anterodistally, posterior surface with some moderately long and long setae; merus, posterodistal lobe narrow and acute, setose; carpus strongly expanded, wider than propodus, anterior margin with ten setae (some delicately plumose), posterodistal lobe subacute, reaching palmar corner of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus shorter than carpus, subchelate, triangular, strongly widening distally, anterior margin with seven long setae regularly placed, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with two spines; dactylus curved, slightly longer than palm. Pereopod 3 (Fig. 16): coxa subrectangular, wider and deeper than coxa 2, ventral margin with some short setae; basis shorter than coxa, narrow, length 4.2 �� width, anterior and posterior margins with some long setae; merus expanded distally, with two groups of setae anteriorly and three groups of setae posteriorly placed; carpus broad, length 1.2 �� merus, posteriorly armed with long setae organized in 11 rows; propodus length 0.7 �� carpus, with five rows of long setae anterodistally and 13 moderately long setae along posterior margin; dactylus thin, longer than propodus (1.4 �� propodus). Pereopod 4 (Fig. 16): coxa wider than deep, anterior margin slightly convex, extending distally, coxa the widest almost at the anteroventral corner, ventral margin armed with small setules, posteroventral lobe huge, blunt, (width to depth ratio of the lobe 1:0.7), posterior margin deeply excavated; basis long and narrow, length 4.7 �� width, anterior and posterior margins with long, delicately plumose setae; merus weakly expanded, setose along anterior and posteror margins, a row of 12 long setae at anterodistal corner, a row of seven moderately long setae at posterodistal corner; carpus broad, length 0.8 �� merus, 11 setae at anterodistal corner, posterior margin armed with c. 40 setae organized in ten rows; propodus narrow, length 0.8 �� carpus, with seven rows of long setae along anterior margin and 9 moderately long setae along posterior margin (in five groups); dactylus stout, longer than propodus (1.5 �� propodus). Pereopod 5 (Fig. 17): coxa about as deep as coxa 4, bilobed, posterior lobe expanded ventrally, ventral margin straight with a few small setules, anterior lobe 0.6 �� depth of posterior lobe; basis narrow, length 3.2 �� width, long, delicately plumose setae at distal quarter of anterior margin (6), at posterior margin (5), and at the surface; merus as long as basis, with four groups of long, delicately plumose setae along anterior margin, four setae at anterodistal corner, four groups of moderately long setae posteriorly; carpus-dactylus broken off. Pereopod 6 (Fig. 17): coxa bilobed but anterior lobe partly damaged, posterior lobe long, distal margin slightly convex; basis narrow, length 3.7 �� width, posterior margin with 18 long and moderately long, delicately plumose setae, row of seven long setae at inner surface; merus length 0.7 �� basis, five rows of setae anteriorly, four rows of setae posteriorly; carpus narrow, length 0.5 �� merus, two rows of setae anteriorly and two rows of setae posteriorly; propodus narrow, length 1.9 �� carpus, 14 setae along distal half of anterior margin and eight rows of setae posteriorly; dactylus broken. Pereopod 7 (Fig. 17): coxa wider than deep, rounded posteriorly; basis ovate, length 1.5 �� width, tapering distally, anterior margin strongly convex with short setae, proximally minute, triangular scales at the surface, posterior margin slightly oblique in distal half, smooth with two setae and a few setules proximally, posterodistal lobe absent; merus length 1.4 �� basis with groups of setae both anteriorly and posteriorly (some setae broken); carpus-propodus broken off. Pleon. Pleonites 1���2 (Fig. 13) with mid-dorsal, relatively long posteriorly directed teeth; pleonite 3 with short, upright tooth. Epimera: 1 and 3 evenly rounded, epimeron 2 posterior margin convex, posterodistal corner subquadrate. Pleopods [pleopod 2 (Fig. 18)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 13) longest; urosomite 3 longer than 2, with short projection above telson. Uropods (Fig. 18): Uropod 1: peduncle length 1.2 �� inner ramus, margins with several short setae; inner ramus 1.3 �� length of outer ramus, with small setae on both margins; outer ramus with setae on lateral margin only. Uropod 2: shorter than uropod 1, peduncle length 0.9 �� inner ramus, with short setae on both margins; inner ramus 1.6 �� length of outer ramus, with short setae on both margins; outer ramus with setae on lateral margin only. Uropod 3: peduncle short, peduncle length 0.3 �� inner ramus; rami subequal, with traces of setae on lateral margins. Telson: (Fig. 18) short, length 1.5 �� width, cleft 30%, lobes subacute, widely diverging, without subapical notches, with terminal setae, with a pair of dorsolateral setae, a few stalked protists (possibly ciliates) attached to the surface. Intraspecific variation: The development of posterior teeth on pleonites 1���3 varies with size. In juveniles (3.1���7.0 mm) the teeth on pleonites 1���2 are weakly developed; however, the upright tooth on pleonite 3 is conspicuous. On the contrary, in larger individuals the teeth on pleonites 1���2 are distinct, whereas the upright tooth on pleonite 3 is weak. Urosomite 1 in some males is posteriorly slightly protruded forming a small hump (absent in females). Large individuals (both males and females) have urosomite 3 produced into a small subacute tooth over the telson. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype female of O. lesci (SMF-56780, GenBank accession number MW 377941) is designed as a hologenophore of all obtained sequences. The sequences of the paratype and additional individuals of the species are deposited in GenBank with the following accession numbers: MN 346311, MW 377926, MW 377928, MW 377929, MW 377933, MW 377936, MW377938, MW377940, MW377946. The species has received also a Barcode Index Number from BOLD: ADF5684 (dx.doi.org/10.5883/BOLD:ADF568). Distribution: KKT area (Fig. 25), 4681���5419 m., Published as part of Ja��d��ewska, Anna M., Brandt, Angelika, Arbizu, Pedro Mart��nez & Vink, Annemiek, 2022, Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods, pp. 181-225 in Zoological Journal of the Linnean Society 194 on pages 199-208, DOI: 10.1093/zoolinnean/zlab032, http://zenodo.org/record/5799308, {"references":["Jazdzewska AM, Mamos T. 2019. High species richness of northwest Pacific deep-sea amphipods revealed through DNA barcoding. Progress in Oceanography 178: 102184.","Pleijel F, Jondelius U, Norlinder E, Nygren A, Oxelman B, Schander C, Sundberg P, Thollesson M. 2008. Phylogenies without roots? A plea for the use of vouchers in molecular phylogenetic studies. Molecular Phylogenetics and Evolution 48: 369 - 371."]}

OEDICERINA TERESAE JAżDżEWSKA, SP. NOV. (FIGS 7���12) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 8B11C501-328E-4F33-AA78-F2229D4847A1. Type material Holotype: Immature ♂, 5.5 mm, body remnants and two slides with appendages, ZMH K-60661, DSB_3680, St. Ma 16���25, 11��49.143��� N, 116��58.492��� W- 11��49.975��� N, 116��57.797��� W; 4107��� 4101 m, 29 April 2016, leg. Annika Janssen. Allotype: Mature ♀ (oostegites setose, no egg), 5.8 mm, ZMH K-60662, DSB_3818, St. AB2-EB12, 12��02.72��� N, 117��25.43��� W- 12��03.03��� N, 117��24.28��� W; 4223���4299 m, 16 March 2015, leg. Inga Mohrbeck. Paratype: One juvenile, 3.4 mm, ZMH K-60663, DSB_3681, St. Ma 16���28, 11��49.654��� N, 117��00.299��� W- 11��49.902��� N, 116��59.174��� W; 4143 ��� 4133 m, 1 May 2016, leg. Annika Janssen. Additional material: One individual sex undetermined, broken in two parts, DNA extracted from anterior part, posterior part preserved but not used for taxonomic evaluation, ZMH K-60664, DSB_3683, St. Ma 16���95, 11��47.862��� N, 117��30.639��� W- 11��47.152��� N, 117��29.490��� W, 4356���4359 m, 9 May 2016, leg. Annika Janssen. The registered type material is deposited in the Zoological Museum of Hamburg, Germany. Type locality: Eastern central Pacific, CCZ, St. Ma 16���25, 11��49.143��� N, 116��58.492��� W- 11��49.975��� N, 116��57.797��� W; 4107��� 4101 m. Etymology: The species is named for Dr. Teresa Jażdżewska, the first author���s mother and a specialist in ephemeropteran and hirudinean taxonomy, diversity and ecology. Description: Based on male, 5.5 mm, St. Ma 16���25. Head (Fig. 7): longer than deep, longer than pereonites 1���2 combined; no eyes or ocular pigment visible; rostrum curved but not deflexed, the angle between head dorsal margin and rostrum margin more than 90 ��, rostrum reaching 2/3 of first article of peduncle of antenna 1; interantennal lobe moderate, subtriangular. Antenna 1 (Fig. 8): subequal in length to antenna 2; length ratios of peduncle articles 1���3 1:0.7:0.4; flagellum 12-articulate, first article longer than article 3 of peduncle; accessory flagellum 1-articulate, minute, slender, length 0.1 �� first flagellum article; peduncle sparsely setose, flagellum naked. Antenna 2 (Fig. 8): peduncle moderately setose; length of article 4 0.9 �� article 5; flagellum broken at sixth article (right antenna 2���7-articulate). Upper lip (labrum) (Fig. 8): damaged during preparation. Mandible (Fig. 8): incisor margins with five (left) or six (right) teeth; left lacinia mobilis six-cusped; right lacinia mobilis narrower with four cusps; accessory spine rows with four slender, pectinate spines; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 length 0.7 �� article 3, with seven posterodistal setae, article 3 slightly tapering distally, anterior margin with three (left) or four (right) setae, posterior margin with 11 setae, apically with two or three setae. Lower lip (Fig. 8): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 8): inner plate oval, with two distal setae; outer plate with eight acute setal-teeth (three/four with bifurcate tips); palp 2-articulate, longer than outer plate, robust, rounded apically, article 1 short, length 0.25 �� article 2, article 2 with eight apical/subapical setae and one long, lateral setae. Maxilla 2 (Fig. 8): inner plate wider than outer, right inner plate also shorter than outer (left subequal in length), inner plate with setae and spines apically and subapically, fine setules along inner and outer margins; outer plate rounded with apical spines and setae, with one moderately long apicolateral setae. Maxilliped (Fig. 9): inner plate subrectangular, reaching about 0.3 �� basal article of palp, apical margin with seven slender spines; outer plate slender and slightly curved, long, reaching 0.5 �� length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; article 1 tapering distally; article 2 triangular, widest at the midpoint, with strong medial setae; article 3 expanded mediodistally, not produced along article 4; article 4 strong, slightly curved; length ratios of articles 1���4 1:1.8:0.7:1. Pereon. Pereonite 1 (Fig. 7) longer than pereonite 2, pereonites 3���6 of similar length, longer than 2, pereonite 7 the longest, extending dorsally into a sharp posteriorly directed tooth. Gnathopod 1 (Fig. 9): coxa subtriangular, anterodistal corner subacute, posterodistal corner rectangular, ventral margin with single short seta anteriorly placed, width to depth ratio 1:1; basis straight, slightly expanded distally, distal half of anterior margin with row of long setae, posterior margin with long setae (some delicately plumose), posterodistal corner with single spine, some short setae on the inner surface; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, anterior margin with six setae along distal half (some delicately plumose), posterior lobe rounded with setae along posterior and distal margins; propodus subchelate, triangular, strongly widening distally, anterior margin moderately setose, palm almost as long as hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, distinctly longer than palm. Gnathopod 2 (Fig. 10): coxa narrow, slightly tapering distally, width 0.5 �� depth, apex rounded, ventral margin naked; basis straight, c. 15 long setae forming circular patch anterodistally, four long setae at posterior margin, three setae at posterodistal corner, some setae at the surface; merus, posterodistal lobe narrow, subacute, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with two setae, posterodistal lobe subacute, extending palmar corner of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus longer than carpus, subchelate, triangular, strongly widening distally, anterior margin with four long setae regularly placed, group of setae at anterodistal corner, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, just longer than palm. Pereopod 3 (Fig. 10): coxa subrectangular, wider and deeper than coxa 2, ventral margin naked; basis longer than coxa, narrow, length 5.4 �� width, some long setae anteriorly; merus slightly expanded distally, two groups of setae anterodistally and three groups of setae posteriorly; carpus narrow, length 1.1 �� merus, one group of setae at anterodistal corner, posteriorly armed with long setae organized in eight groups; propodus length 0.6 �� carpus, with a group of setae anterodistally and five groups of moderately long setae along posterior margin; dactylus thin, as long as propodus. Pereopod 4 (Fig. 10): coxa wider than deep, anterior margin strongly convex, extending distally, coxa the widest almost at 2/3 of its depth, ventral margin naked, posteroventral lobe huge, blunt (width to depth ratio of the lobe 1:0.7), posterior margin deeply excavated; basis long and narrow, length 5.4 �� width, sparse long setae at anterior and posterior margin as well as on the surface; merus slightly expanded, sparsely setose; carpus-dactylus broken off. Pereopod 5 (Fig. 11): coxa about as deep as coxa 4, bilobed, posterior lobe expanded ventrally, ventral margin straight, with one seta anteriorly placed, anterior lobe 0.5 �� depth of posterior lobe; basis narrow, length 2.8 �� width, five long, delicately plumose setae at anterior margin, three long setae along posterior margin; merus as long as basis, sparsely setose; carpus-dactylus broken off. Pereopod 6 (Fig. 11): coxa partly damaged; basis narrow, length 3.3 �� width, sparsely setose; merus as long as basis, sparsely setose; carpus-dactylus broken off. Pereopod 7 (Fig. 11): coxa wider than deep, rounded posteriorly; basis ovate, length 1.6 �� width, widest in the mid length, tapering distally, anterior margin strongly convex, one short spine at anterodistal corner, posterior margin slightly oblique in distal half, denticulate, posterodistal lobe absent; merus distally damaged, with groups of setae both anteriorly and posteriorly (some setae broken); carpus-dactylus broken off. Pleon. Pleonites 1���3 (Fig. 7) with distinct mid-dorsal, posteriorly directed teeth. Epimera: 1 and 3 evenly rounded, epimeron 2 posterodistal corner subquadrate, epimeron 3 delicately serrate. Pleopods [pleopod 1 (Fig. 12)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 7) longest, produced distally into a sharp, large, upright tooth; urosomite 3 longer than 2. Uropods (Fig. 12): Uropod 1 (damaged): peduncle margins with some moderately long setae; rami broken off. Uropod 2 (rami damaged): peduncle with some moderately long setae; inner ramus with sparse setae. Uropod 3: peduncle short, peduncle length 0.3 �� inner ramus; inner and outer ramus with short spines along lateral margins. Telson: (Fig. 12) short, length 1.5 �� width, cleft 35%, lobes subacute, widely diverging, notched subapically, tips unequal in size (inner slightly shorter than outer; on one side outer tip broken), single seta placed in the notch. Intraspecific variation: No distinct differences were observed between the holotype and the mature female collected. The difference between adult individuals and the juveniles is expressed by the number of articles of flagella of antenna 1 and antenna 2 which is smaller in the latter. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype male of O. teresae (ZMH K-60661, GenBank accession number MW 377944) is designed as a hologenophore of all obtained sequences. The sequences of the paratype and additional individuals of the species are deposited in GenBank with the following accession numbers: MW 377925, MW 377934, MW 377942. The species has received also a Barcode Index Number from BOLD: AEB1523 (dx.doi.org/10.5883/ BOLD: AEB1523). Distribution: Eastern central Pacific, CCZ (Fig. 25), 4101���4359 m., Published as part of Ja��d��ewska, Anna M., Brandt, Angelika, Arbizu, Pedro Mart��nez & Vink, Annemiek, 2022, Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods, pp. 181-225 in Zoological Journal of the Linnean Society 194 on pages 193-199, DOI: 10.1093/zoolinnean/zlab032, http://zenodo.org/record/5799308, {"references":["Pleijel F, Jondelius U, Norlinder E, Nygren A, Oxelman B, Schander C, Sundberg P, Thollesson M. 2008. Phylogenies without roots? A plea for the use of vouchers in molecular phylogenetic studies. Molecular Phylogenetics and Evolution 48: 369 - 371."]}

Oedicerotidae sp. 10 Jażdżewska, 2015 Oedicerina sp. Golovan et al., 2019 (excluding one individual from station 2���9 and one in dividual from station 5���10)., Published as part of Ja��d��ewska, Anna M., Brandt, Angelika, Arbizu, Pedro Mart��nez & Vink, Annemiek, 2022, Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods, pp. 181-225 in Zoological Journal of the Linnean Society 194 on page 199, DOI: 10.1093/zoolinnean/zlab032, http://zenodo.org/record/5799308, {"references":["Jazdzewska A. 2015. Kuril-Kamchatka deep sea revisited - insights into the amphipod abyssal fauna. Deep-Sea Research Part II 111: 294 - 300.","Golovan OA, Blazewicz M, Brandt A, Jazdzewska A, Jozwiak P, Lavrenteva AV, Malyutina MV, Petryashov VV, Riehl T, Sattarova VV. 2019. Diversity and distribution of peracarid crustaceans (Malacostraca) from the abyss adjacent to the Kuril-Kamchatka Trench. Marine Biodiversity 49: 1343 - 1360."]}

Jażdżewska, Anna M., Brandt, Angelika, Arbizu, Pedro Martínez, Vink, Annemiek (2022): Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods. Zoological Journal of the Linnean Society 194: 181-225, DOI: 10.1093/zoolinnean/zlab032

OEDICERINA HENRICI JAżDżEWSKA, SP. NOV. (FIGS 2–6) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 9A993D45-B781-4479-A4D6-2EC840D1BC3E. Type material Holotype: ♂, 6.5 mm, body remnants and two slides with appendages, ZMH K-60658, DSB_3762, St. AB2-EB04, 12°07.83’ N, 117°18.67’ W- 12°08.02’ N, 117°17.52’ W, 4111–4122 m, 25 February 2015, leg. Inga Mohrbeck. Paratype: Immature ♂, urosome missing, individual originally in one piece, broke into three parts during examination, one slide with appendages, ZMH K-60659, DSB_3682, St. Ma 16–95, 11°47.862’ N, 117°30.639’ W- 11°47.152’ N, 117°29.490’ W, 4356–4359 m, 9 May 2016, leg. Annika Janssen. Additional material: One ovigerous ♀ (single egg), individual found in two parts, DNA is extracted from the anterior part, posterior part preserved but not used for taxonomic evaluation, ZMH K-60660, DSB_3582, St. SO 262-156, 11°49.381’ N, 117°32.663’ W- 11°49.752’ N, 117°30.760’ W, 4340– 4340 m, 9 May 2018, leg. Pedro Martínez Arbizu. The registered type material is deposited in the Zoological Museum of Hamburg, Germany. Type locality: Eastern central Pacific, CCZ, St. AB 2-EB04, 12°07.83’ N, 117°18.67’ W- 12°08.02’ N, 117°17.52’ W, 4111–4122 m. Etymology: The species is named for Prof. Krzysztof Henryk (Latin Henricus) Jażdżewski, the first author’s father and renowned specialist in amphipod taxonomy, diversity and ecology. Description: Based on male, 6.1 mm, St. AB2-EB04. Head (Fig. 2): longer than deep, longer than pereonites 1–3 combined; no eyes or ocular pigment visible; rostrum strongly deflexed, the angle between head dorsal margin and rostrum margin 90 ° or less, rostrum as long as first article of peduncle of antenna 1; interantennal lobe weak, rounded. Antenna 1 (Fig. 3; broken in holotype at first peduncular article, description based on paratype): length ratios of peduncle articles 1–3 1:0.7:0.3; flagellum broken at 11th article; accessory flagellum 1-articulate, minute, slender, one fourth of the length of first flagellum article; sparse setae placed both on peduncle and flagellar articles. Antenna 2 (Fig. 3; broken in holotype at first peduncular article, description based on paratype): peduncle moderately setose; length of article 4 1.4 × article 5; peduncular article 5 with short setae along dorsal margin; flagellum shorter than peduncle article 5, 7-articulate (but last flagellar articles broken off), sparse setae placed distally on flagellar articles. Upper lip (labrum) (Fig. 3): wider than long, rounded apically, with fine setules laterally. Mandible (Fig. 3): incisor margins with five teeth; left lacinia mobilis five-cusped; right lacinia mobilis narrower with five cusps; accessory spine rows with five-six serrate setae; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 equal in length to article 3, with 9–10 posterodistal setae, article 3 slightly tapering distally, anterior margin with three to four setae, posterior margin with a row of 30 setae of different length. Lower lip (Fig. 3): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 3): inner plate oval, with two distal setae; outer plate with nine acute setal-teeth (three with bifurcate tips); palp 2-articulate, longer than outer plate, slender, rounded apically, article 1 short, length 0.3 × article 2, article 2 with 10–11 apical/subapical setae and two lateral setae. Maxilla 2 (Fig. 3): left— inner plate shorter than outer, right—plates subequal in length, inner plate slightly tapering distally, width about 1.1 × outer, with setae and spines apically and subapically, fine setules along inner margin; outer plate rounded with apical spines and setae, with four apicolateral setae. Maxilliped (Fig. 4) (due to very strong staining of the holotype during preparation for CLSM some setae, especially placed on the surface of maxilliped not visible): inner plate subrectangular, reaching about 0.3 × basal article of palp, apical margin with eight slender spines; outer plate slender and slightly curved, long, reaching almost 0.5 × length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; surface of article 2 with minute, triangular scales; article 1 slightly tapering distally; article 2 triangular, widest at the midpoint, with strong medial setae; article 3 expanded mediodistally, but not produced along article 4; article 4 strong, slightly curved; length ratios of articles 1–4 1:1.7:0.7:1. Pereon. Pereonite 1 (Fig. 2) longer than 2, pereonite 3 same length as 2; pereonites 4–5 successively longer; pereonite 6 shorter than pereonite 5, pereonite 7 the longest, extending dorsally into sharp posteriorly directed tooth. Gnathopod 1 (Fig. 4): coxa subtriangular, distinctly produced anteriorly, anterodistal corner narrowly rounded, posterodistal corner rectangular, ventral margin naked, width to depth ratio 1:0.7; basis straight, weakly expanded, distal half of anterior margin with four long setae and c. 10 moderately long setae, posterior margin without setae, single spine at posterodistal corner; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, anterior margin naked, posterior lobe subacute with setae along posterior margin and a few setae placed at distal margin; propodus subchelate, triangular, strongly widening distally, anterior margin with four setae in two groups, palm slightly shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with single spine; dactylus curved, longer than palm. Gnathopod 2 (Figs 4, 5) (broken in holotype at basis; described based on paratype): coxa narrow, slightly tapering distally, width 0.7 × depth, apex rounded, ventral margin naked; basis straight, six thin setae at inner surface of anterior margin, 20 long setae forming circular patch anterodistally, posterior margin with two moderately long setae, single spine at posterodistal corner; merus, posterodistal lobe narrow, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with a few sparsely placed setae, posterodistal lobe subacute, exceeding palm of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus shorter than carpus, subchelate, triangular, strongly widening distally, anterior margin with six long setae regularly placed, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with single spine; dactylus curved, longer than palm. Pereopod 3 (Fig. 5): coxa subrectangular, slightly larger than coxa 2, ventral margin naked; basis long and narrow, length 4.5 × width, posterior margin with traces of three short setae, single short spine at posterodistal corner; merus expanded distally, almost naked; carpus length 1.2 × merus, posteriorly armed with long setae organized in eight groups; propodus length 0.6 × carpus, with three groups of long setae anterodistally and c. 15 moderately long setae along posterior margin; dactylus thin, shorter than propodus (0.7 × propodus). Pereopod 4 (Fig. 6): right—coxa wider than deep, anterior margin slightly convex, posteroventral lobe huge, blunt, slightly narrowing distally (width to depth ratio of the lobe 1:0.5), posterior margin deeply excavated; basis long and narrow, length 5.8 × width, single short spine at posterodistal corner; merus weakly expanded; carpus-dactylus broken off; left—coxa partially damaged, not dissected; basis long and narrow, length 6 × width, two short setae along posterior margin, single short spine at posterodistal corner; merus weakly expanded; carpus subequal in length to merus, posteriorly armed with long setae organized in eight groups; propodus length 0.6 × carpus, with three groups of long setae anterodistally and long setae along posterior margin; dactylus slender, shorter than propodus (0.8 × propodus). Pereopod 5 (Fig. 6): coxa bilobed (partly broken); basis narrow, length 3.4 × width, traces of nine setae along distal half of anterior margin, two short setae at anterodistal corner; merus length 0.9 × basis, with traces of four setae along anterior margin; carpus 0.5 × length of merus armed with 13 setae organized in four groups along posterior margin; propodus slender, 1.1 × length of merus, with groups of setae at posterior margin and at lateral surface; dactylus slender, length 0.7 × propodus. Pereopod 6 (Fig. 6): coxa bilobed but anterior lobe very small, posterior lobe long, distal margin slightly convex; basis narrow, length 3.1 × width, traces of nine setae along distal half of anterior margin, one short seta at anterodistal corner; merus length 0.7 × basis; carpus-dactylus broken off. Pereopod 7 (Fig. 6): coxa wider than deep, rounded posteriorly; basis ovate, length 1.7 × width, tapering distally, anterior margin strongly convex with a few sparse short setae, posterior margin rather straight, crenate, posterodistal lobe absent; merus as long as basis with a few setae along anterior and posterior margins; carpus-dactylus broken off. Pleon. Pleonites 1–2 (Fig. 2) with mid-dorsal, relatively long posteriorly directed teeth; pleonite 3 with short, slender, posteriorly directed tooth. Epimera: 1–3 evenly rounded, epimeron 3 crenulated. Pleopods [pleopod 2 (Fig. 6)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 2) longest, with a small hump on dorsal surface in the mid length of the urosomite and a distinct, sharp upright tooth at the posterior margin; urosomite 3 longer than 2, depressed anteriorly, with acute mid-dorsal projection over telson. Uropods: damaged. Telson (Fig. 6): short, length 1.4 × width, cleft 45%, lobes apically damaged, widely diverging, with one seta on dorsal surface. Intraspecific variation: Due to the bad condition of the individuals not much can be said about sexual or size-dependent dimorphism within the studied species. The only observed difference is the smaller size of the posterodorsal tooth on pleonite 3 in the immature male. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype male of O. henrici (ZMH K-60658, GenBank accession number MW 377935) is designed as a hologenophore of all obtained sequences. The sequences of the paratype and an additional individual of the species are deposited in GenBank with the following accession numbers: MW 377932, MW 377937. The species has also received a Barcode Index Number from BOLD: AEB1524 (dx.doi. org/10.5883/ BOLD: AEB1524). Distribution: Eastern central Pacific, CCZ (Fig. 25), 4111–4359 m.

OEDICERINA CLAUDEI JAżDżEWSKA, SP. NOV. (FIGS 19–23) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: D1CB7EA5-FC38-406F-A101-BC5EBE7E1762. Type material Holotype: Juvenile, 4.5 mm, body remnants and two slides with appendages, SMF-56781, St. AKL-71-1-9, 46°05.037’ N, 146°00.465’ E- 46°08.727’ N, 146°00.227’ E; 3307– 3307 m, 10 July 2015, leg. Marina V. Malyutina. The registered type material is deposited in the Senckenberg Museum (Frankfurt, Germany). Type locality: Sea of Okhotsk, St. AKL-71-1-9, 46°05.037’ N, 146°00.465’ E- 46°08.727’ N, 146°00.227’ E; 3307– 3307 m. Etymology: The species is named for Dr. Claude De Broyer, a great friend and one of the first author’s scientific mentors and renowned specialist in amphipod taxonomy, diversity and ecology. Description: Based on juvenile, 4.5 mm, St. AKL-71-1-9. Head (Fig. 19): longer than deep, longer than pereonites 1–4 combined; no eyes or ocular pigment visible; rostrum deflexed, the angle between head dorsal margin and rostrum margin almost 90 °, rostrum reaching the end of first article of peduncle of antenna 1; interantennal lobe indistinct. Antenna 1 (Fig. 20): length ratios of peduncle articles 1–3 1:0.7:0.4, peduncle article 1 laterally acutely produced; flagellum 5-articulate, first article as long as article 3 of peduncle; accessory flagellum 1-articulate, minute, slender, length 0.2 × first flagellum article; peduncle and flagellum sparsely setose. Antenna 2 (Fig. 20, considerably damaged): length of peduncle article 4 1.5 × article 5. Upper lip (labrum) (Fig. 20): wider than long, rounded apically, with fine setules laterally. Mandible (Fig. 20): incisor margins with five teeth; left lacinia mobilis four-cusped; right lacinia mobilis narrower slightly cuspidate; accessory spine rows with five serrate setae; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 1.1 × longer than article 3, with four posterodistal setae, article 3 slightly tapering distally, anterior margin with two setae, posterior margin with two setae, three setae at apex. Lower lip (Fig. 20): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 20): inner plate oval, with two distal setae; outer plate with eight acute setal-teeth (three with bifurcate tips); palp 2-articulate, longer than outer plate, slender, rounded apically, article 1 short, length 0.2 × article 2, article 2 with five or six apical/subapical setae and one long, lateral setae. Maxilla 2 (Fig. 20): left—plates subequal in length, right—inner plate shorter than outer, inner plate width about 1.1 × outer, with setae and spines apically and subapically, fine setules along inner margin; outer plate rounded with apical spines and setae, outer margin with fine setules. Maxilliped (Fig. 21): inner plate subrectangular, reaching about 0.3 × basal article of palp, apical margin with six slender spines; outer plate slender and slightly curved, long, reaching 0.4 × length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; article 1 tapering distally; article 2 triangular, widest at 0.6 × length, setose medially; article 3 expanded mediodistally, slightly produced along article 4; article 4 strong, slightly curved; length ratios of articles 1–4 1:1.9:0.7:1.3. Pereon. Pereonite 1 (Fig. 19) twice as long as pereonite 2, pereonite 3 longer than 2, pereonites 4–5 subequal in length, longer than pereonites 1–3, pereonites 6–7 of the same length, longer than all preceding segments. Gnathopod 1 (Figs 19, 21): coxa subtriangular, anterodistal corner bluntly rounded, posterodistal corner rectangular, ventral margin naked, width to depth ratio 1:0.8; basis straight, slightly expanded distally, distal half of anterior margin with row of long setae, sparse setae on the surface; merus, posterodistal lobe subquadrate, moderately setose; carpus strongly expanded, anterior margin with five setae along distal half, posterior lobe subacute with setae along posterior and distal margins; propodus subchelate, triangular, strongly widening distally, anterior margin moderately setose, palm longer than hind margin, transverse, strongly convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, longer than palm. Gnathopod 2 (Figs 19, 21): coxa narrow, slightly tapering distally, width 0.4 × depth, apex rounded, ventral margin naked; basis straight, 16 long setae forming circular patch anterodistally, single moderately long, delicately plumose seta at posterior margin; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with four setae (some delicately plumose), posterodistal lobe subacute, extending palmar corner of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus shorter than carpus, subchelate, triangular, strongly widening distally, anterior margin with eight long setae regularly placed, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, slightly longer than palm. Pereopod 3 (Figs 19, 22): coxa subrectangular, wider and deeper than coxa 2, ventral margin naked; basis shorter than coxa, narrow, length 3.1 × width, anterior and posterior margins with some long, delicately plumose setae; merus expanded distally, one group of setae anterodistally and two groups of setae posteriorly; carpus broad, length 1.2 × merus, posteriorly armed with long setae; propodus length 0.8 × carpus, with six long setae anterodistally and seven long setae along posterior margin; dactylus stout, longer than propodus (1.2 × propodus). Pereopod 4 (Figs 19, 22): coxa wider than deep, anterior margin strongly convex, extending distally, coxa the widest almost at 2/3 of its depth, ventral margin naked, posteroventral lobe huge, blunt, (width to depth ratio of the lobe 1:0.9), posterior margin deeply excavated; basis long and narrow, length 3.5 × width, anterior margin with four long, delicately plumose setae, posterior margin with one long, delicately plumose setae, short seta at posterodistal corner; merus expanded, a few setae at anterior margin, one short seta at posterior margin, group of long setae at posterodistal corner; carpus expanded, length 0.8 × merus, five setae at anterodistal corner, posterior margin armed with 11 long and moderately long setae; propodus narrow, length 0.5 × carpus, moderately setose at anterior and posterior margins; dactylus stout, longer than propodus (1.9 × propodus). Pereopod 5 (Fig. 22): right—coxa about as deep as coxa 4, bilobed, posterior lobe expanded ventrally, ventral margin straight, naked, anterior lobe 0.5 × depth of posterior lobe; basis narrow, length 4.1 × width, five long, delicately plumose setae at anterior margin; merus as long as basis, with three groups of moderately long plumose setae along anterior margin, seven setae at anterodistal corner, two setae at posterior margin and a group of four setae at posterodistal corner; carpusdactylus broken off; left—coxa about as deep as coxa 4, bilobed, posterior lobe partially damaged; basis narrow, length 2.5 × width, two long, delicately plumose setae at anterior margin, two long setae at the surface (one delicately plumose); merus 1.1 × basis, with three groups of moderately long setae along anterior margin, four setae at anterodistal corner, two setae at posterior margin; carpus length 0.5 × merus, with five setae anterodistally; propodus length 1.6 × carpus length, with three setae anterodistally; dactylus stout, longer than propodus (1.2 × propodus length). Pereopod 6 (Fig. 22): coxa bilobed but anterior lobe very small, posterior lobe long, distal margin slightly convex; basis narrow, length 3.9 × width, anterior margin with seven long, delicately plumose setae along distal half, posterior margin with five long, delicately plumose setae along distal half; merus length 0.7 × basis, three rows of setae anteriorly, two rows of setae posteriorly; carpusdactylus broken off. Pereopod 7 (Fig. 22): coxa wider than deep, rounded posteriorly; basis ovate, length 1.5 × width, widest in the mid-length, tapering distally, anterior margin strongly convex, two short spines at anterodistal corner, posterior margin slightly oblique in distal half, smooth, posterodistal lobe nearly as long as ischium; merus length 1.2 × basis with groups of setae both anteriorly and posteriorly (some setae broken); carpus-dactylus broken off. Pleon. Pleonite 1 (Fig. 19) produced posteriorly, pleonites 2–3 with distinct mid-dorsal, posteriorly directed teeth. Epimera: 1 and 3 evenly rounded, epimeron 2 posterior margin convex, posterodistal corner subquadrate. Pleopods [pleopod 2 (Fig. 23)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 19) longest; urosomite 3 longer than 2. Uropods (Fig. 23): Uropod 1: peduncle length 1.1 × inner ramus, margins with some short setae; inner ramus 1.4 × length of outer ramus, rami with sparse setae. Uropod 2: shorter than uropod 1, peduncle length 0.9 × inner ramus, with some short setae; inner ramus 1.2 × length of outer ramus, rami with sparse setae. Uropod 3: peduncle short, peduncle length 0.4 × inner ramus; inner ramus with short spines along distal half of lateral margins; outer ramus damaged. Telson: (Fig. 23) short, length 1.7 × width, cleft 40%, lobes subacute, widely diverging, notched subapically, tips unequal in size (inner longer than outer), single seta placed in the notch, single dorsolateral seta on the surface. Sexual dimorphism: No sexual or size-dependent variation observed as the individual is unique. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype juvenile of O. claudei (SMF-56781, GenBank accession number MW 377945) is designed as a hologenophore of all obtained sequences. The species has received also a Barcode Index Number from BOLD: AEA4699 (dx.doi. org/10.5883/ BOLD: AEA 4699). Distribution: Sea of Okhotsk (Fig. 25), 3307 m. MOLECULAR INVESTIGATION Each of the morphologically recognized species received a unique Barcode Index Number. Across all species, the intraspecific diversity calculated on haplotypes is low, ranging from 0.002 (O. lesci) to 0.005 (O. henrici) for both K2P and p -distance. Each of the species is represented by three haplotypes (Table 2; Fig. 24B). An exception is O. claudei, as only one individual of this taxon was collected. The distances between the studied taxa varies from 0.059 to 0.238 of p -distance and from 0.061 to 0.289 of K2P (Table 3). The lowest interspecies distances are noted between O. lesci and O. ingolfi, irrespective of the measures applied. The highest values are observed for O. henrici and O. claudei for both measures and for O. henrici and O. ingolfi for p -distance only (Fig. 24A). The haplotype networks show a star-like topology (Fig. 24B). In O. lesci, the central, ancestral and dominant haplotype is present at five stations including the stations situated on both sides of the KKT. In O. henrici and O. teresae, the central, ancestral haplotypes are missing.

OEDICERINA LESCI JAżDżEWSKA, SP. NOV. (FIGS 13���18) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 8242F310-A152-4CB7-8BE3-EAAF8A848D9A., Published as part of Ja��d��ewska, Anna M., Brandt, Angelika, Arbizu, Pedro Mart��nez & Vink, Annemiek, 2022, Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods, pp. 181-225 in Zoological Journal of the Linnean Society 194 on page 199, DOI: 10.1093/zoolinnean/zlab032, http://zenodo.org/record/5799308

OEDICERINA HENRICI JAżDżEWSKA, SP. NOV. (FIGS 2���6) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 9A993D45-B781-4479-A4D6-2EC840D1BC3E. Type material Holotype: ♂, 6.5 mm, body remnants and two slides with appendages, ZMH K-60658, DSB_3762, St. AB2-EB04, 12��07.83��� N, 117��18.67��� W- 12��08.02��� N, 117��17.52��� W, 4111���4122 m, 25 February 2015, leg. Inga Mohrbeck. Paratype: Immature ♂, urosome missing, individual originally in one piece, broke into three parts during examination, one slide with appendages, ZMH K-60659, DSB_3682, St. Ma 16���95, 11��47.862��� N, 117��30.639��� W- 11��47.152��� N, 117��29.490��� W, 4356���4359 m, 9 May 2016, leg. Annika Janssen. Additional material: One ovigerous ♀ (single egg), individual found in two parts, DNA is extracted from the anterior part, posterior part preserved but not used for taxonomic evaluation, ZMH K-60660, DSB_3582, St. SO 262-156, 11��49.381��� N, 117��32.663��� W- 11��49.752��� N, 117��30.760��� W, 4340��� 4340 m, 9 May 2018, leg. Pedro Mart��nez Arbizu. The registered type material is deposited in the Zoological Museum of Hamburg, Germany. Type locality: Eastern central Pacific, CCZ, St. AB 2-EB04, 12��07.83��� N, 117��18.67��� W- 12��08.02��� N, 117��17.52��� W, 4111���4122 m. Etymology: The species is named for Prof. Krzysztof Henryk (Latin Henricus) Jażdżewski, the first author���s father and renowned specialist in amphipod taxonomy, diversity and ecology. Description: Based on male, 6.1 mm, St. AB2-EB04. Head (Fig. 2): longer than deep, longer than pereonites 1���3 combined; no eyes or ocular pigment visible; rostrum strongly deflexed, the angle between head dorsal margin and rostrum margin 90 �� or less, rostrum as long as first article of peduncle of antenna 1; interantennal lobe weak, rounded. Antenna 1 (Fig. 3; broken in holotype at first peduncular article, description based on paratype): length ratios of peduncle articles 1���3 1:0.7:0.3; flagellum broken at 11th article; accessory flagellum 1-articulate, minute, slender, one fourth of the length of first flagellum article; sparse setae placed both on peduncle and flagellar articles. Antenna 2 (Fig. 3; broken in holotype at first peduncular article, description based on paratype): peduncle moderately setose; length of article 4 1.4 �� article 5; peduncular article 5 with short setae along dorsal margin; flagellum shorter than peduncle article 5, 7-articulate (but last flagellar articles broken off), sparse setae placed distally on flagellar articles. Upper lip (labrum) (Fig. 3): wider than long, rounded apically, with fine setules laterally. Mandible (Fig. 3): incisor margins with five teeth; left lacinia mobilis five-cusped; right lacinia mobilis narrower with five cusps; accessory spine rows with five-six serrate setae; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 equal in length to article 3, with 9���10 posterodistal setae, article 3 slightly tapering distally, anterior margin with three to four setae, posterior margin with a row of 30 setae of different length. Lower lip (Fig. 3): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 3): inner plate oval, with two distal setae; outer plate with nine acute setal-teeth (three with bifurcate tips); palp 2-articulate, longer than outer plate, slender, rounded apically, article 1 short, length 0.3 �� article 2, article 2 with 10���11 apical/subapical setae and two lateral setae. Maxilla 2 (Fig. 3): left��� inner plate shorter than outer, right���plates subequal in length, inner plate slightly tapering distally, width about 1.1 �� outer, with setae and spines apically and subapically, fine setules along inner margin; outer plate rounded with apical spines and setae, with four apicolateral setae. Maxilliped (Fig. 4) (due to very strong staining of the holotype during preparation for CLSM some setae, especially placed on the surface of maxilliped not visible): inner plate subrectangular, reaching about 0.3 �� basal article of palp, apical margin with eight slender spines; outer plate slender and slightly curved, long, reaching almost 0.5 �� length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; surface of article 2 with minute, triangular scales; article 1 slightly tapering distally; article 2 triangular, widest at the midpoint, with strong medial setae; article 3 expanded mediodistally, but not produced along article 4; article 4 strong, slightly curved; length ratios of articles 1���4 1:1.7:0.7:1. Pereon. Pereonite 1 (Fig. 2) longer than 2, pereonite 3 same length as 2; pereonites 4���5 successively longer; pereonite 6 shorter than pereonite 5, pereonite 7 the longest, extending dorsally into sharp posteriorly directed tooth. Gnathopod 1 (Fig. 4): coxa subtriangular, distinctly produced anteriorly, anterodistal corner narrowly rounded, posterodistal corner rectangular, ventral margin naked, width to depth ratio 1:0.7; basis straight, weakly expanded, distal half of anterior margin with four long setae and c. 10 moderately long setae, posterior margin without setae, single spine at posterodistal corner; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, anterior margin naked, posterior lobe subacute with setae along posterior margin and a few setae placed at distal margin; propodus subchelate, triangular, strongly widening distally, anterior margin with four setae in two groups, palm slightly shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with single spine; dactylus curved, longer than palm. Gnathopod 2 (Figs 4, 5) (broken in holotype at basis; described based on paratype): coxa narrow, slightly tapering distally, width 0.7 �� depth, apex rounded, ventral margin naked; basis straight, six thin setae at inner surface of anterior margin, 20 long setae forming circular patch anterodistally, posterior margin with two moderately long setae, single spine at posterodistal corner; merus, posterodistal lobe narrow, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with a few sparsely placed setae, posterodistal lobe subacute, exceeding palm of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus shorter than carpus, subchelate, triangular, strongly widening distally, anterior margin with six long setae regularly placed, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with single spine; dactylus curved, longer than palm. Pereopod 3 (Fig. 5): coxa subrectangular, slightly larger than coxa 2, ventral margin naked; basis long and narrow, length 4.5 �� width, posterior margin with traces of three short setae, single short spine at posterodistal corner; merus expanded distally, almost naked; carpus length 1.2 �� merus, posteriorly armed with long setae organized in eight groups; propodus length 0.6 �� carpus, with three groups of long setae anterodistally and c. 15 moderately long setae along posterior margin; dactylus thin, shorter than propodus (0.7 �� propodus). Pereopod 4 (Fig. 6): right���coxa wider than deep, anterior margin slightly convex, posteroventral lobe huge, blunt, slightly narrowing distally (width to depth ratio of the lobe 1:0.5), posterior margin deeply excavated; basis long and narrow, length 5.8 �� width, single short spine at posterodistal corner; merus weakly expanded; carpus-dactylus broken off; left���coxa partially damaged, not dissected; basis long and narrow, length 6 �� width, two short setae along posterior margin, single short spine at posterodistal corner; merus weakly expanded; carpus subequal in length to merus, posteriorly armed with long setae organized in eight groups; propodus length 0.6 �� carpus, with three groups of long setae anterodistally and long setae along posterior margin; dactylus slender, shorter than propodus (0.8 �� propodus). Pereopod 5 (Fig. 6): coxa bilobed (partly broken); basis narrow, length 3.4 �� width, traces of nine setae along distal half of anterior margin, two short setae at anterodistal corner; merus length 0.9 �� basis, with traces of four setae along anterior margin; carpus 0.5 �� length of merus armed with 13 setae organized in four groups along posterior margin; propodus slender, 1.1 �� length of merus, with groups of setae at posterior margin and at lateral surface; dactylus slender, length 0.7 �� propodus. Pereopod 6 (Fig. 6): coxa bilobed but anterior lobe very small, posterior lobe long, distal margin slightly convex; basis narrow, length 3.1 �� width, traces of nine setae along distal half of anterior margin, one short seta at anterodistal corner; merus length 0.7 �� basis; carpus-dactylus broken off. Pereopod 7 (Fig. 6): coxa wider than deep, rounded posteriorly; basis ovate, length 1.7 �� width, tapering distally, anterior margin strongly convex with a few sparse short setae, posterior margin rather straight, crenate, posterodistal lobe absent; merus as long as basis with a few setae along anterior and posterior margins; carpus-dactylus broken off. Pleon. Pleonites 1���2 (Fig. 2) with mid-dorsal, relatively long posteriorly directed teeth; pleonite 3 with short, slender, posteriorly directed tooth. Epimera: 1���3 evenly rounded, epimeron 3 crenulated. Pleopods [pleopod 2 (Fig. 6)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 2) longest, with a small hump on dorsal surface in the mid length of the urosomite and a distinct, sharp upright tooth at the posterior margin; urosomite 3 longer than 2, depressed anteriorly, with acute mid-dorsal projection over telson. Uropods: damaged. Telson (Fig. 6): short, length 1.4 �� width, cleft 45%, lobes apically damaged, widely diverging, with one seta on dorsal surface. Intraspecific variation: Due to the bad condition of the individuals not much can be said about sexual or size-dependent dimorphism within the studied species. The only observed difference is the smaller size of the posterodorsal tooth on pleonite 3 in the immature male. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype male of O. henrici (ZMH K-60658, GenBank accession number MW 377935) is designed as a hologenophore of all obtained sequences. The sequences of the paratype and an additional individual of the species are deposited in GenBank with the following accession numbers: MW 377932, MW 377937. The species has also received a Barcode Index Number from BOLD: AEB1524 (dx.doi. org/10.5883/ BOLD: AEB1524). Distribution: Eastern central Pacific, CCZ (Fig. 25), 4111���4359 m., Published as part of Ja��d��ewska, Anna M., Brandt, Angelika, Arbizu, Pedro Mart��nez & Vink, Annemiek, 2022, Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods, pp. 181-225 in Zoological Journal of the Linnean Society 194 on pages 186-192, DOI: 10.1093/zoolinnean/zlab032, http://zenodo.org/record/5799308, {"references":["Pleijel F, Jondelius U, Norlinder E, Nygren A, Oxelman B, Schander C, Sundberg P, Thollesson M. 2008. Phylogenies without roots? A plea for the use of vouchers in molecular phylogenetic studies. Molecular Phylogenetics and Evolution 48: 369 - 371."]}

OEDICERINA LESCI JAżDżEWSKA, SP. NOV. (FIGS 13–18) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 8242F310-A152-4CB7-8BE3-EAAF8A848D9A.

OEDICERINA TERESAE JAżDżEWSKA, SP. NOV. (FIGS 7–12) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 8B11C501-328E-4F33-AA78-F2229D4847A1. Type material Holotype: Immature ♂, 5.5 mm, body remnants and two slides with appendages, ZMH K-60661, DSB_3680, St. Ma 16–25, 11°49.143’ N, 116°58.492’ W- 11°49.975’ N, 116°57.797’ W; 4107– 4101 m, 29 April 2016, leg. Annika Janssen. Allotype: Mature ♀ (oostegites setose, no egg), 5.8 mm, ZMH K-60662, DSB_3818, St. AB2-EB12, 12°02.72’ N, 117°25.43’ W- 12°03.03’ N, 117°24.28’ W; 4223–4299 m, 16 March 2015, leg. Inga Mohrbeck. Paratype: One juvenile, 3.4 mm, ZMH K-60663, DSB_3681, St. Ma 16–28, 11°49.654’ N, 117°00.299’ W- 11°49.902’ N, 116°59.174’ W; 4143 – 4133 m, 1 May 2016, leg. Annika Janssen. Additional material: One individual sex undetermined, broken in two parts, DNA extracted from anterior part, posterior part preserved but not used for taxonomic evaluation, ZMH K-60664, DSB_3683, St. Ma 16–95, 11°47.862’ N, 117°30.639’ W- 11°47.152’ N, 117°29.490’ W, 4356–4359 m, 9 May 2016, leg. Annika Janssen. The registered type material is deposited in the Zoological Museum of Hamburg, Germany. Type locality: Eastern central Pacific, CCZ, St. Ma 16–25, 11°49.143’ N, 116°58.492’ W- 11°49.975’ N, 116°57.797’ W; 4107– 4101 m. Etymology: The species is named for Dr. Teresa Jażdżewska, the first author’s mother and a specialist in ephemeropteran and hirudinean taxonomy, diversity and ecology. Description: Based on male, 5.5 mm, St. Ma 16–25. Head (Fig. 7): longer than deep, longer than pereonites 1–2 combined; no eyes or ocular pigment visible; rostrum curved but not deflexed, the angle between head dorsal margin and rostrum margin more than 90 °, rostrum reaching 2/3 of first article of peduncle of antenna 1; interantennal lobe moderate, subtriangular. Antenna 1 (Fig. 8): subequal in length to antenna 2; length ratios of peduncle articles 1–3 1:0.7:0.4; flagellum 12-articulate, first article longer than article 3 of peduncle; accessory flagellum 1-articulate, minute, slender, length 0.1 × first flagellum article; peduncle sparsely setose, flagellum naked. Antenna 2 (Fig. 8): peduncle moderately setose; length of article 4 0.9 × article 5; flagellum broken at sixth article (right antenna 2–7-articulate). Upper lip (labrum) (Fig. 8): damaged during preparation. Mandible (Fig. 8): incisor margins with five (left) or six (right) teeth; left lacinia mobilis six-cusped; right lacinia mobilis narrower with four cusps; accessory spine rows with four slender, pectinate spines; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 length 0.7 × article 3, with seven posterodistal setae, article 3 slightly tapering distally, anterior margin with three (left) or four (right) setae, posterior margin with 11 setae, apically with two or three setae. Lower lip (Fig. 8): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 8): inner plate oval, with two distal setae; outer plate with eight acute setal-teeth (three/four with bifurcate tips); palp 2-articulate, longer than outer plate, robust, rounded apically, article 1 short, length 0.25 × article 2, article 2 with eight apical/subapical setae and one long, lateral setae. Maxilla 2 (Fig. 8): inner plate wider than outer, right inner plate also shorter than outer (left subequal in length), inner plate with setae and spines apically and subapically, fine setules along inner and outer margins; outer plate rounded with apical spines and setae, with one moderately long apicolateral setae. Maxilliped (Fig. 9): inner plate subrectangular, reaching about 0.3 × basal article of palp, apical margin with seven slender spines; outer plate slender and slightly curved, long, reaching 0.5 × length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; article 1 tapering distally; article 2 triangular, widest at the midpoint, with strong medial setae; article 3 expanded mediodistally, not produced along article 4; article 4 strong, slightly curved; length ratios of articles 1–4 1:1.8:0.7:1. Pereon. Pereonite 1 (Fig. 7) longer than pereonite 2, pereonites 3–6 of similar length, longer than 2, pereonite 7 the longest, extending dorsally into a sharp posteriorly directed tooth. Gnathopod 1 (Fig. 9): coxa subtriangular, anterodistal corner subacute, posterodistal corner rectangular, ventral margin with single short seta anteriorly placed, width to depth ratio 1:1; basis straight, slightly expanded distally, distal half of anterior margin with row of long setae, posterior margin with long setae (some delicately plumose), posterodistal corner with single spine, some short setae on the inner surface; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, anterior margin with six setae along distal half (some delicately plumose), posterior lobe rounded with setae along posterior and distal margins; propodus subchelate, triangular, strongly widening distally, anterior margin moderately setose, palm almost as long as hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, distinctly longer than palm. Gnathopod 2 (Fig. 10): coxa narrow, slightly tapering distally, width 0.5 × depth, apex rounded, ventral margin naked; basis straight, c. 15 long setae forming circular patch anterodistally, four long setae at posterior margin, three setae at posterodistal corner, some setae at the surface; merus, posterodistal lobe narrow, subacute, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with two setae, posterodistal lobe subacute, extending palmar corner of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus longer than carpus, subchelate, triangular, strongly widening distally, anterior margin with four long setae regularly placed, group of setae at anterodistal corner, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, just longer than palm. Pereopod 3 (Fig. 10): coxa subrectangular, wider and deeper than coxa 2, ventral margin naked; basis longer than coxa, narrow, length 5.4 × width, some long setae anteriorly; merus slightly expanded distally, two groups of setae anterodistally and three groups of setae posteriorly; carpus narrow, length 1.1 × merus, one group of setae at anterodistal corner, posteriorly armed with long setae organized in eight groups; propodus length 0.6 × carpus, with a group of setae anterodistally and five groups of moderately long setae along posterior margin; dactylus thin, as long as propodus. Pereopod 4 (Fig. 10): coxa wider than deep, anterior margin strongly convex, extending distally, coxa the widest almost at 2/3 of its depth, ventral margin naked, posteroventral lobe huge, blunt (width to depth ratio of the lobe 1:0.7), posterior margin deeply excavated; basis long and narrow, length 5.4 × width, sparse long setae at anterior and posterior margin as well as on the surface; merus slightly expanded, sparsely setose; carpus-dactylus broken off. Pereopod 5 (Fig. 11): coxa about as deep as coxa 4, bilobed, posterior lobe expanded ventrally, ventral margin straight, with one seta anteriorly placed, anterior lobe 0.5 × depth of posterior lobe; basis narrow, length 2.8 × width, five long, delicately plumose setae at anterior margin, three long setae along posterior margin; merus as long as basis, sparsely setose; carpus-dactylus broken off. Pereopod 6 (Fig. 11): coxa partly damaged; basis narrow, length 3.3 × width, sparsely setose; merus as long as basis, sparsely setose; carpus-dactylus broken off. Pereopod 7 (Fig. 11): coxa wider than deep, rounded posteriorly; basis ovate, length 1.6 × width, widest in the mid length, tapering distally, anterior margin strongly convex, one short spine at anterodistal corner, posterior margin slightly oblique in distal half, denticulate, posterodistal lobe absent; merus distally damaged, with groups of setae both anteriorly and posteriorly (some setae broken); carpus-dactylus broken off. Pleon. Pleonites 1–3 (Fig. 7) with distinct mid-dorsal, posteriorly directed teeth. Epimera: 1 and 3 evenly rounded, epimeron 2 posterodistal corner subquadrate, epimeron 3 delicately serrate. Pleopods [pleopod 1 (Fig. 12)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 7) longest, produced distally into a sharp, large, upright tooth; urosomite 3 longer than 2. Uropods (Fig. 12): Uropod 1 (damaged): peduncle margins with some moderately long setae; rami broken off. Uropod 2 (rami damaged): peduncle with some moderately long setae; inner ramus with sparse setae. Uropod 3: peduncle short, peduncle length 0.3 × inner ramus; inner and outer ramus with short spines along lateral margins. Telson: (Fig. 12) short, length 1.5 × width, cleft 35%, lobes subacute, widely diverging, notched subapically, tips unequal in size (inner slightly shorter than outer; on one side outer tip broken), single seta placed in the notch. Intraspecific variation: No distinct differences were observed between the holotype and the mature female collected. The difference between adult individuals and the juveniles is expressed by the number of articles of flagella of antenna 1 and antenna 2 which is smaller in the latter. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype male of O. teresae (ZMH K-60661, GenBank accession number MW 377944) is designed as a hologenophore of all obtained sequences. The sequences of the paratype and additional individuals of the species are deposited in GenBank with the following accession numbers: MW 377925, MW 377934, MW 377942. The species has received also a Barcode Index Number from BOLD: AEB1523 (dx.doi.org/10.5883/ BOLD: AEB1523). Distribution: Eastern central Pacific, CCZ (Fig. 25), 4101–4359 m.

GENUS OEDICERINA STEPHENSEN, 1931 Known species: Oedicerina ingolfi Stephensen, 1931; O. megalopoda Ledoyer, 1986; O. denticulata Hendrycks & Conlan, 2003; O. loerzae Coleman & Thurston, 2014; O. vaderi Coleman & Thurston, 2014., Published as part of Ja��d��ewska, Anna M., Brandt, Angelika, Arbizu, Pedro Mart��nez & Vink, Annemiek, 2022, Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods, pp. 181-225 in Zoological Journal of the Linnean Society 194 on page 186, DOI: 10.1093/zoolinnean/zlab032, http://zenodo.org/record/5799308, {"references":["Stephensen K. 1931. Crustacea Malacostraca VII (Amphipoda III). The Danish Ingolf-Expedition 3: 179 - 290.","Ledoyer M. 1986. Crustaces amphipodes gammariens. Familles des Haustoriidae a Vitjazianidae. Faune de Madagascar 59 (2). Paris: ORSTOM Institut Francais de Recherche Scientifique pour le Developement en Cooperation, 599 - 1112.","Hendrycks EA, Conlan KE. 2003. New and unusual abyssal gammaridean Amphipoda from the north-east Pacific. Journal of Natural History 37: 2303 - 2368.","Coleman CO, Thurston MH. 2014. A redescription of the type species of Oedicerina Stephensen, 1931 (Crustacea, Amphipoda, Oedicerotidae) and the description of two new species. Zoosystematics and Evolution 90: 225 - 247."]}

Im Fokus der siebten Ausgabe des »World Ocean Review« stehen die Auswirkungen des Klimawandels auf die Physik des Meeres und auf seine Lebensgemeinschaften; die Folgen von Fischerei, Schifffahrt, Ressourcenabbau, Energiegewinnung und Meeresverschmutzung sowie die Fragen, wie sich Wirkstoffe aus dem Meer nutzen lassen und wie der Ozean künftig so verwaltet werden kann, dass sowohl sein Schutz als auch die Teilhabe möglichst aller Menschen an seinen Leistungen und Gütern gewährleistet sind.