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Cheliplana varicauda Brunet, 1971 Material examined. Reference material. 2 whole mounts (SMNH 82471–82472) and 1 serially sectioned specimen (SMNH Type 3034). Known distribution. Bay of Valdibora, Rovinj, Croatia (Brunet 1971). Golfe de Marseille, France (Brunet 1971). Remarks. Our observations correspond to those of Brunet (1971). Live specimens appear orange-pink. The caudal region is conspicuous and highly extensible, similar to the situation in Cheliplana sarnensis. Near the caudal body end, a single, continuous adhesive girdle is present. A pair of seminal vesicles and prostatic glands empty into the proximal end of the elongate copulatory bulb and form an elongate prostatic vesicle. A long, curved ejaculatory duct is present, which distally becomes a sclerotised cirrus, armed with fine spines. Longitudinal muscles surround the copulatory bulb. Circular muscles were not observed. The copulatory organ opens into a small male atrium, which immediately connects to a common genital atrium. The latter receives the female atrial organs and a large, globular mass of lightly coloured (eosinophilic) glands. Coarse-grained, basophilic cement glands also empty into the common genital atrium close to the gonopore. The opening of the vagina externa is located a short distance posterior to the gonopore. The vaginal walls are sinuous and muscular, clearly surrounded by longitudinal muscles. The vaginal opening can be closed with a sphincter. Proximally, the vagina leads on into a large, syncytial and poorly delineated bursa, which shows large vacuoles containing sperm. Three sclerotised spermatic ducts connect the bursa to the large ovary, situated alongside the male copulatory apparatus and the bursa., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 485, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1971) Cheliplana varicauda n. sp., nouveau turbellarie calyptorynque de la famille des Karkinorhynchidae. Annales de l'Universite ' de Provence-Sciences, 45, 25 - 28."]}

Cheliplana setosa Evdonin, 1971 Fig. 9A–D Material examined. New material. CANADA • 1 whole mount; British Columbia, Calvert Island, Foggy Cove; 51°39’07”N, 128°08’32”W; 9 Apr. 2016; medium-grained sand in between boulders in the lower intertidal; MI4193 • 1 whole mount; British Columbia, Bamfield, Brady Beach; 48°49’40”N, 125°09’12”W; 3 Jun. 2015; mediumgrained sand in lower intertidal; MI4194. Reference material. 1 whole-mounted specimen (SMNH 90403) and 1 serially sectioned specimen (SMNH 102990) from California, United States. Known distribution. Posyet, Peter the Great Gulf, Russia (Evdonin 1977). Monterey Bay, California, United States (Karling 1983). Ría de Villaviciosa, near San Martin, Spain (Noreña et al. 2007). Remarks. Live specimens are ~ 1.5 mm long. Specimens are yellowish to pinkish in colour (Fig. 9A). The proboscis bears curved proboscis hooks measuring 18–20 μm (h, Fig. 9C). Hook supports are about 12 μm long in the specimens from Canada (hs, Fig. 9C). Rod-shaped, weakly sclerotised proboscis sidepieces were observed by Karling (1983). The prepharyngeal tube is armed with spines (ppc, Fig. 9A). A single, large testis is situated alongside the pharynx (ph, t, Fig. 9A). Karling (1983) reports a lobe containing sperm at the posterior end of the testis. A pair of seminal vesicles, one of which ending blindly, the other connecting to the testis via an unpaired vas deferens, enter the proximal end of the copulatory bulb (cb, vs, Fig. 9A–B,D). The copulatory bulb is oviform (cb, Fig. 9A–B,D). In the Russian specimens, Evdonin (1971) measures a size range of 110 to 120 μm for the copulatory bulb. The Californian specimen described by Karling (1983) possesses a copulatory bulb of ~130 μm. The copulatory bulbs in the new specimens from Canada are somewhat larger still, measuring 130–160 μm. The copulatory bulb holds a cirrus of 40–60 μm (Russia and California) (Evdonin 1971; Karling 1983) or 68–85 μm (Canada) (ci, Fig. 9 A–B,D). The cirrus can be divided in three clearly defined regions: (1) a proximal tube-like region of ~48 μm (California) to 48–60 μm (Canada), armed with fine spines, (2) a ring of five or six large spines of about 10–15 μm (Canada) long, set in sclerotised pockets, and (3) a distal region of ~7 μm (California) to 15–17 μm (Canada) long, wider than the proximal region, armed with hair-like spines. A single ovary (ov, Fig. 9A) and bursa are situated near the caudal body end., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 480-482, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Evdonin, L. A. (1971) The interstitial Kalyptorhynchia (Turbellaria, Neorhabdocoela) from the bay of Peter the Great of the Sea of Japan. Akademii Nauk SSSR Issledovanija Fauna Morei, 8 (16), 55 - 71.","Karling, T. G. (1989) New taxa of Kalyptorhynchia (Platyhelminthes) from the N. American Pacific coast. Zoologica Scripta, 18 (1), 19 - 32. https: // doi. org / 10.1111 / j. 1463 - 6409.1989. tb 00120. x","Evdonin, L. A. (1977) Monograph of the Turbellaria Kalyptorhynchia in the fauna of the USSR and adjacent areas. Fauna USSR, Turbellaria, 1 (Pt. 1.), New Series, 115, 1 - 400.","Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x","Norena, C., Damborenea, C., Faubel, A. & Brusa, F. (2007) Composition of meiobenthonic Platyhelminthes from brackish environments of the Galician and Cantabrian coasts of Spain with the description of a new species of Djeziraia (Polycystididae, Kalyptorhynchia). Journal of Natural History, 41 (29 - 32), 1989 - 2005. https: // doi. org / 10.1080 / 00222930701526055."]}

Cheliplana asinaraensis n. sp. Gobert, Reygel & Artois Fig. 1A–B Etymology. The species epithet ‘asinaraensis’ refers to the National Park of Asinara (Sardinia, Italy), where the specimen was found. Material examined. Holotype. ITALY • 1 whole mount; Punta Tumbarino, Asinara National Park, Sardinia; 41°02’17”N, 08°13’13”E; 29 Sep. 2014; 29 m depth, coarse gravel with silt from a channel among rocks; KV.633. Description. The specimen is ~ 1.5 mm long, transparent and colourless. The proboscis is large, with an overall length of ~50 μm (p, Fig. 1A). The hook supports measure ~20–22 μm, and the smooth, evenly curved proboscis hooks measure ~38 μm. The mouth is situated ventrally, posterior to the proboscis, and is connected to the pharynx via a long, unarmed oral tube. The anterior edge of the pharynx is lined with papillae. A single testis is positioned alongside the pharynx (t, Fig. 1A). The common genital opening is situated in the posterior 1/5 of the body and is surrounded by glands (gp, Fig. 1A). The atrial organs of the male and female genital system surround the gonopore. The male copulatory system consists of a pair of relatively large seminal vesicles (vs, Fig. 1A), which enter the elongate copulatory bulb proximally. At the same location, a large group of prostatic glands enter the bulb and form a prostatic vesicle in the proximal half of the copulatory bulb (pg, Fig. 1A). The distal half of the ejaculatory duct forms a sclerotised cirrus with an overall length of 60 μm (ci, Fig. 1A; Fig. 1B). The cirrus consists of two clearly defined regions (Fig. 1B). The proximal part is a sclerotised, straight tube, which shows a longitudinal striation. Towards the distal end of this part, fine triangular spines are present. The distal, 18- μm-long part of the cirrus is crescent-shaped and eccentrically curved. The outer part of the crescent is armed with very fine, bristle-like spines, while in the central part, large, but thin lamellae are present. A large ovary is positioned adjacent to the male copulatory system (ov, Fig. 1A). An oviduct or ductus communis could not be observed. A vaginal opening is situated medioventrally, directly anterior to the adhesive girdle. The vagina externa is surrounded by longitudinal or diagonal muscles. Circular muscles may be present as well, but this was impossible to ascertain from the whole-mounted specimen. A constriction separates the vagina from a large, sac-like bursa (b, Fig. 1A). The proximal end of the bursa shows a small, globular part, provided with a small, funnel-shaped spermatic duct., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 457, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692

Cheliplana asica Marcus, 1952 Material examined. Reference material. 1 whole mount and 3 serially sectioned specimens from Brazil (SMNH 109332–109335) Known distribution. São Paulo, Brazil (Marcus 1952). Holguín, Cuba (Diez et al. 2019). Remarks. Based on differences in cirrus morphology and the bursa-ovary connection, Brunet (1968) divided Cheliplana asica in two subspecies, C. asica asica from Brazil and C. asica terminalis from the Mediterranean and West Indian Ocean. We now consider both subspecies to be separate species (see remarks on C. terminalis Brunet, 1968). Our observations on the Brazilian species correspond to Marcus’ description (Marcus 1952) and the notes by Brunet, 1968. Live specimens are ~ 1.8 mm long, with a single, caudal adhesive belt. The proboscis is armed with 12–15-µmlong hooks and provided with a pair of short, sclerotised sidepieces. The postrostral bulb measures 30 μm by 10 μm and is surrounded by circular muscles. The prepharyngeal tube is lined with an epithelium forming microvilli. The pharynx is characterised by papillae on its rostral edge. The single testis is positioned ventro-caudally to the pharynx. A pair of efferent ducts leads from the testis to a pair of spindle-shaped seminal vesicles, which in turn enter the proximal end of a slender copulatory bulb along with prostatic glands. The proximal end of the copulatory bulb is ~12 μm wide and is bordered by a high epithelium. The entire copulatory apparatus is ~280 μm long. The ejaculatory duct forms a long, unarmed, sclerotised cirrus., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 465, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Marcus, E. (1952) Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo, 17, 5 - 188.","Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1","Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana hawaiiensis n. sp. Gobert, Reygel, Van Steenkiste & Artois Fig. 2A–C, Fig. 3A–C, Fig. 4 Etymology. The species epithet refers to the Hawaiian archipelago, where the species was first found. Material examined. Holotype. UNITED STATES • 1 whole mount; Hawaii, Oahu, Waimanalo Beach; 21°19’36”N, 157°40’59”W; 31 May 2010; intertidal zone, fine sand with organic detritus among blocks of coral; KV.635. Other material. UNITED STATES • 6 whole mounts and two serial sections; Hawaii, Oahu, Waimanalo Beach; 21°19’36”N, 157°40’59”W; 31 May 2010; intertidal zone, fine sand with organic detritus among blocks of coral; HU X.2.26–X.2.33. CANADA • 3 whole mounts; British Columbia, Calvert Island, West Beach; 51°39’24”N, 128°08’41”W; 3 Jun. 2015; intertidal zone, medium-grained sand from the beach surface; MI4186–MI4188 • 3 whole mounts; British Columbia, Calvert Island, North Beach; 51°39’52”N, 128°08’46”W; 7 Jun. 2017; coarse sand in lower intertidal; MI4189–MI4191 • 1 whole mount; British Columbia, Calvert Island, Foggy Cove; 51°39’07”N, 128°08’32”W; 9 Apr. 2016; medium-grained sand in between boulders in the lower intertidal; MI4192. Description. Specimens are largely transparent, with a weak brown to orange colouration (Figs. 3A, 4A). A caudal haptic girdle is present (ag, Fig. 2A). The proboscis of the Hawaiian specimens is ~37 μm long with 18-μmlong muscular hook supports and a pair of smooth proboscis hooks ~20 μm long (h, hs, Fig. 3B). The proboscis of the Canadian specimens is about 28 μm long with 10-μm-long hook supports and 18 μm long hooks (h, hs, Fig. 4B; 4D). The proboscis sidepieces are straight, non-sclerotised rods, with enlarged distal ends, bearing a single bristle (sp, Figs. 3B; 4B). The mouth is situated directly posterior to the proboscis. The pharynx is positioned in the anterior part of the body (ph, Figs. 2A; 3A; 4A) and connects to the mouth via a long, slender oral cavity lined with spines (ppc, Fig. 2A; 4A). The anterior edge of the pharynx is lined with papillae. In some specimens, the body contains large numbers of diatom frustules. A single testis is present in the anterior body half, just behind and/or alongside the pharynx (t, Fig. 2A; 3A; 4A). The posterior part of the testis shows a globular accumulation of sperm, probably corresponding to the area where the testis connects to the vas deferens. The male copulatory bulb measures ~117 μm in the Hawaiian specimens (cb, Fig. 3A) and 75–100 µm in the Canadian specimens (cb, Fig. 4A,C,E). Two seminal vesicles enter the copulatory bulb proximally (vs, Figs. 2A; 4A,C). The copulatory bulb is of the conjuncta duplex type (Karling 1956) and is surrounded by a sheath of longitudinal muscles. The presence of circular muscles surrounding the copulatory bulb could not be determined. The large prostatic glands also enter the copulatory bulb proximally and form a prostatic vesicle in the proximal part of the bulb (pg, vg, Figs. 2A; 3A; 4A,C). The distal part of the bulb holds the ejaculatory duct, the distal end of which forms an armed cirrus (Figs. 2C; 3C; ci, Figs. 2A; 3A; 4A,C,E) measuring 30–40 μm (Canada) or 41–68 μm (Hawaii). The cirrus is differentiated in three distinct regions (Figs. 2C; 4E): the most proximal part is tubular, with a length of 15–31 μm (x = 21 μm, n = 6; Hawaii) or 12–18 μm (x = 15 μm, n = 7; Canada) and a diameter of 8–16 μm (x = 12 μm, n = 6; Hawaii) or 7–9 μm (x = 8 μm, n = 7; Canada). This part is armed with very fine spines with a rectangular base. This proximal tube is followed distally by a ring of six long, curved spines of ~12 μm long (measured on Canadian specimens), each set in sclerotised pockets. The most distal region is 23–34 μm (x = 27 μm, n = 6; Hawaii) or 12–17 μm (x = 15 μm, n = 7; Canada) long, with a diameter of ~17–26 μm (x = 22 μm, n = 6; Hawaii) or 12–17 μm (x = 14 μm, n = 7; Canada). This distal part is lined with densely stacked, bristle-like spines with a length of ~8 μm (Hawaii) or ~5 μm (Canada). A single, large ovary is present near the copulatory apparatus (ov, Fig. 4A). A bursa is situated posterior to the common genital opening (b, Fig. 4A,C). No spermatic duct or vagina externa were observed., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 459-461, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Karling, T. G. (1956) Morphologisch-histologische Untersuchungen an den mannlichen Atrialorganen der Kalyptorhynchia (Turbellaria). Arkiv for Zoologi, Serie 2, Band 9 (7), 187 - 279."]}

Cheliplana gibarenha Diez, Reygel & Artois, 2019 Material examined. None. Known distribution. Gibara, Cuba (Diez et al. 2019). Remarks (summarised from literature).Whole-mounted specimens are ~ 0.8 mm long.The body is transparent. The proboscis has a pair of muscular hook supports (5 µm) and 14-µm-long, curved hooks. The mouth opens just caudally from the postrostral bulb. The pharynx is slightly shorter than the spiny prepharyngeal cavity. The single testis lies next to the pharynx and is connected to a single, caudally positioned seminal vesicle (184 µm x 28 µm) through a very long vas deferens. The copulatory bulb is directed forward and comprises an elongate prostate vesicle and the cirrus (140 µm x 4 µm). The distal 13 µm of the cirrus is armed with small spines (0.5 µm). The distal part of the copulatory bulb is characterised by a strong sphincter surrounding the cirrus. The single ovary is positioned near the transition between the seminal vesicle and prostate vesicle. Oocytes lie in a row and proximally decrease in diameter. The caudally positioned bursa appears bipartite and opens caudally into the vagina., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 473, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1"]}

Cheliplana curini Gobert, Reygel & Artois, 2017 Material examined. Reference material. 9 whole-mounted specimens, including the holotype (SMNH Type 8905; VII.4.29– VII.4.36), and 8 serially sectioned specimens (HU VII.4.37– VII.4.44) from Lanzarote and Sardinia. Known distribution. Lanzarote, Canary Islands, Spain (Gobert et al. 2017). Sardinia, Italy (Gobert et al. 2017). Remarks. Live specimens are ~ 0.8–1.3 mm long, with orange to bright red pigmentation. The proboscis is ~40 μm long, with smooth hooks measuring 20–27 μm and hook supports of ~20–30 μm. A pair of soft, rod-shaped proboscis sidepieces, without bristles, is present. The horizontally oriented pharynx measures approximately 1/5 of the total body length and connects to the mouth via a long, unarmed prepharyngeal tube. A single testis is positioned near the caudal end of the pharynx. In the posterior half of the body, an elongate copulatory bulb (350–370 μm) is present. A pair of seminal vesicles enters the proximal end of the copulatory bulb, which contains a globular prostatic vesicle. A long ejaculatory duct runs axially through the copulatory bulb. Distally, it forms a sclerotised, unarmed cirrus (56–74 μm) surrounded by three blind-ending accessory cirri. The latter respectively measure 43–50 μm, 50–80 μm and 60–75 μm. Each accessory cirrus is provided with fine spines. The cirrus and accessory cirri merge into a thinly sclerotised, unarmed ‘sleeve’, which makes up a distal penis papilla. A muscular vagina externa opens caudally to the gonopore. The interior lumen of the vagina is lined with a thickened basal lamina, forming a pseudo-cuticula. The vagina connects to a large bursa that consists of two parts: a non-muscular, syncytial region, containing large vesicles adjacent to the ovary, and a distal, saclike region. No spermatic duct between the ovary and bursa is present., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 467, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Gobert, S., Reygel, P. & Artois, T. (2017) Schizorhynchia (Platyhelminthes, Rhabdocoela) of Lanzarote (Canary Islands), with the description of eight new species. Marine Biodiversity, 49 (5), 2089 - 2107. https: // doi. org / 10.1007 / s 12526 - 017 - 0736 - x."]}

Cheliplana remanei (Meixner, 1928) Karling, 1983 Fig. 8A–B Synonyms. Rhinepera remanei Meixner, 1928. Material examined. New material. GERMANY • 2 whole mounts; Sylt, beach south of List harbour; 55°00’55”N, 6°26’11”E; 28 Apr. 2015; spot with algae and somewhat coarser sediment than the surrounding silt; HU X.2.41– X.2.42. Note. No reference material was available to us at the time of this study Known distribution. Strander Bay, Germany (Meixner 1928). Kiel Bay, Germany (Meixner 1928; Schmidt 1972). Sylt, Germany (Hellwig 1987; Scherer 1985; Noldt 1989). Römö, Denmark (Schilke 1970). Eastern Scheldt, the Netherlands (Martens & Schockaert 1981). Remarks. Meixner (1928) reports an average body length of 0.72 mm, measured on multiple fixed specimens. Live specimens are colourless.A single, continuous caudal haptic girdle is present subterminally.The small proboscis is armed with a pair of smooth, curved hooks, measuring ~18 μm (Meixner 1928) (17–21 μm in our specimens). A pair of soft proboscis sidepieces has been reported, projecting from the base of the muscular hook supports and bearing a 10–12-µm-long bristle (Meixner 1928; Noldt 1989). We did not observe the sidepieces in the newly collected material. The postrostral bulb measures approximately three times the length of the proboscis. The cylindrical pharynx is situated in the anterior third of the body and connected to the mouth via a long prepharyngeal cavity. The interior surface of the prepharyngeal cavity is lined with 4–7 μm-long sclerotised spines, organised in 5 longitudinal rows according to Meixner (1928). Noldt (1989) counted 8–10 rows of spines, measuring 8–11 μm. We were unable to count the spine rows in the newly collected specimens. A single, large testis is situated alongside the posterior end of the pharynx. An unpaired seminal vesicle enters the proximal end of the copulatory bulb (cb, vs, Fig. 8B). The bulb is entirely packed with parenchymatic tissue (Noldt 1989) and surrounded by a layer of longitudinal muscles. A prostatic vesicle is present in the proximal part of the bulb (vg, Fig. 8B), surrounding the ejaculatory duct. According to Noldt (1989), the prostatic glands empty into the ejaculatory duct near the base of the cirrus. The cirrus is curved and consists of a short, proximal, unarmed, ring-like region (10–12 μm long according to Noldt (1989); 10–21 μm in our specimens, n = 2), followed by a curved, asymmetrical part, armed with bristle-like spines (85–110 μm long according to Noldt (1989); 118–142 μm in our specimens, n = 2) (ci, Fig. 8A–B). The spines are maximally 9 μm long. At the distal end, the cirrus is unarmed and partially everted to form a sclerotised penis papilla that protrudes into the male atrium (pp, Fig. 8A–B). In the newly collected specimens from Sylt, the penis papilla measures 20–34 μm (n = 2), though this length likely depends on the contraction state of the copulatory apparatus. Noldt (1989) reports a diameter of 18–25 μm for the penis papilla. Noldt (1989) presents no information on the female genital tract. In our specimens, a single large ovary is visible posterior to the male copulatory bulb. A bursa lies adjacent to the ovary. No vagina (interna or externa) or spermatic duct between the bursa and ovary was observed., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 478-479, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Meixner, J. (1928) Aberrante Kalyptorhynchia (Turbellaria Rhabdocoela) aus dem Sande der Kieler Bucht. Zoologischer Anzeiger, 77, 229 - 253.","Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x","Schmidt, P. (1972) Zonierung und jahreszeitliche Fluktuationen des Mesopsammons im Sandstrand von Schilksee (Kieler Bucht). Mikrofauna Meeresbodens, 10, 1 - 60.","Hellwig, M. (1987) Oekologie freilebender Plathelminthen im Grenzraum Watt-Salzwiese lenitischer Gezeitenkusten. Microfauna Marina, 3, 157 - 244.","Scherer, B. (1985) Annual dynamics of a meiofauna community from the \" sulfide layer \" of a North Sea sand flat. Microfauna Marina, 2, 117 - 162.","Noldt, U. (1989) Kalyptorhynchia (Plathelminthes) from sublittoral coastal areas near the island of Sylt (North Sea) I. Schizorhynchia. Microfauna Marina, 5, 7 - 85.","Schilke, K. (1970) Kalyptorhynchia (Turbellaria) aus dem Eulitoral der deutschen Nordseekuste. Helgolander wissenschaftliche Meeresuntersuchungen, 21, 143 - 265. https: // doi. org / 10.1007 / BF 01630522","Martens, P. M. & Schockaert, E. R. (1981) Sand dwelling Turbellaria from the Netherlands Delta area. Hydrobiologia, 84, 113 - 127. https: // doi. org / 10.1007 / BF 00026169","Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana targa (Marcus, 1952) Karling, 1983 Synonyms. Rhinepera targa Marcus, 1952 Known distribution. Bay of Santos, Brazil (Marcus 1952). Material examined. None. Remarks (summarised from literature). Marcus (1952) describes C. targa as a small species (0.3–0.9 mm total body length). A single testis is located ventrally, at the caudal end of the pharynx. A single efferent duct leads from the caudal end of the testis towards a seminal vesicle, which enters the proximal end of the copulatory bulb. The copulatory bulb is thick-walled, surrounded by a sheath of longitudinal muscles and contains a prostatic vesicle in its proximal part., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 483, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Marcus, E. (1952) Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo, 17, 5 - 188.","Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x"]}

Cheliplana californica Karling, 1989 Fig. 9E Material examined. New material. CANADA • British Columbia, Vancouver, Wreck Beach; 49°15’48”N, 123°15’46”W; 10 Apr. 2015; 1 whole mount; superficial sediment with coarse fraction near rocky headland in the lower intertidal; MI4181. Reference material. 2 whole mounts, including the holotype, and 1 serially sectioned specimen from California (SMNH Type 6799; SMNH 90402). Known distribution. Elkhorn Slough, Monterey Bay, California, United States (Karling 1989). Remarks. Our observations correspond to the original description by Karling (1989). Specimens are ~ 1 mm long and colourless. The caudal haptic girdle is described as consisting of approximately 40 papillae. The cylindrical pharynx is connected to the mouth through a long prepharyngeal tube lined with hair-like bristles. A pair of testes lies alongside the pharynx and the two testes are connected to each other across the oral tube. The oviform male copulatory bulb measures ~95 μm in the Canadian specimen (cb, Fig. 9E) and 118–123 μm in specimens from California (n = 2). The copulatory bulb encloses a short ejaculatory duct, which distally continues in an asymmetrically armed cirrus (ci, Fig. 9E). The cirrus in the specimen from Canada is smaller (~30 μm) compared to the cirrus in Californian specimens (43–47 μm, n = 2). The cirrus spines measure 4–10 μm, increasing in length towards the distal end on one side, while decreasing in length towards the distal end on the other side. Distally, the cirrus ends in a short, sclerotised tube, which may be everted to form a cylindrical papilla. The yolk glands are paired. A non-muscular vagina externa is present, with the opening lying directly anterior to the gonopore. The external vagina opens into a large bursa, which is connected to the single ovary through a spermatic duct., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 466, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Karling, T. G. (1989) New taxa of Kalyptorhynchia (Platyhelminthes) from the N. American Pacific coast. Zoologica Scripta, 18 (1), 19 - 32. https: // doi. org / 10.1111 / j. 1463 - 6409.1989. tb 00120. x"]}

Cheliplana terminalis Brunet, 1968 Fig. 8C–D Synonyms. Cheliplana asica terminalis Brunet, 1968 Material examined. New material. AUSTRALIA • 2 whole mounts; Port Lincoln, Coffin Bay, Kellidie Bay; 34°36’41”S, 13°31’03”E; 8 Dec. 2010; along turn-off to airstrip, coarse-grained sand and shell gravel; HU X.2.02– X.2.03. FRANCE • 1 whole mount; Cerbère, Terrimbo; 19 Jul. 2007; mixture of fine and coarse sand, fairly clean with little silt, from within the bay at a depth of 8 m; HU VIII.4.28 • 1 whole mount; Cerbère, Terrimbo, Les Aloès; 27 Jul. 2012; directly in front of the scaffold, 50 m into the sea, fine sand from a depth of 6 m; HU VIII.4.29 • 2 whole mounts; Canet-en-Rousillon, Canet-Plage; 31 Aug. 2016; pure, fine sand from beach in front of parking harbour, from a depth of 0.5 m; HU VIII.4.36 & HU VIII.4.38 • 3 whole mounts; Canet-en-Rousillon, Canet-Plage; 31 Aug. 2016; pure, fine sand from bend in beach, from a depth of 0.4 m; HU VIII.4.37 & HU VIII.4.39–HU VIII.4.40. SPAIN • 1 whole mount; Catalonia, Blanes; 20 Jul. 2012; sand patches from the north side of a rock with footpath; coarse, clean sand with vegetal debris from a depth of 3 to 4 m; HU VIII.4.34. Reference material. Two serially sectioned specimens from France, one of which the holotype (SMNH Type 2816, SMNH 82468). Known distribution. Provence-Alpes-Côte d’Azur, France (Brunet 1968). Djezira, Mogadishu, Somalia (Schockaert 1982). Mombasa, Kenya (Jouk & De Vocht 1989). Santiago de Cuba and Chivirico, Cuba (Diez et al. 2019). Remarks. According to Brunet’s (1968) description, live specimens are pink and measure ~ 1.6 mm. The proboscis hooks reach a length of 15–16 μm. The copulatory organ is highly similar to that of C. asica as described by Marcus (1952), but differs in the sclerotised distal end of the cirrus (Fig. 8C–D) and the sclerotised penis papilla that surrounds it (pp, Fig. 8C–D). The female system also exhibits a number of differences. According to Brunet (1968), the bursa in C. terminalis connects to the ovary via a well-differentiated spermatic duct provided with a small sclerotised piece, while in C. asica, the bursa connects to the female genital duct (ductus communis). While we were unable to confirm the bursa-female duct connection on material of C. asica, we would argue that the above-mentioned features of the male and female system, if correctly observed, are differential diagnostic characters. As such, we consider C. terminalis and C. asica two separate species. The specimens collected from Somalia and described by Schockaert (1982) likely belong to C. terminalis, because of the presence of a sclerotised penis papilla and the greater degree of sclerotisation of the distal end of the cirrus (compared to Marcus’ (1952) description of C. asica). However, it should be noted that without additional information on the female system, the identification of these specimens as C. terminalis is somewhat tenuous. Furthermore, the specimens from Somalia are substantially smaller than the size ranges described by Brunet (1968). The new specimens from Australia fall more or less within the size range reported by Brunet (1968) and share the long, sclerotised and largely unarmed cirrus with a distal, sclerotised penis papilla. The characters of the female system, however, were not observed., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 483-484, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440.","Schockaert, E. R. (1982) Turbellaria from Somalia. II. Kalyptorhynchia (part 2). Monitore Zoologico Italiano, 17, 81 - 96. https: // doi. org / 10.1080 / 03749444.1982.10736660","Jouk, P. E. H. & De Vocht, A. J. - P. (1989) Kalyptorhynchia (Plathelminthes Rahbdocoela) from the Kenyan Coast, with description of four new species. Tropical Zoology, 2, 145 - 157. https: // doi. org / 10.1080 / 03946975.1989.10539435.","Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1","Marcus, E. (1952) Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo, 17, 5 - 188."]}

Cheliplana verrucosa Diez, Reygel & Artois, 2019 Material examined. None. Known distribution. Bueycabón, Cuba (Diez et al. 2019). Remarks (summarised from literature). Live specimens are pinkish in colour and ~ 0.7 mm long. The epidermis is covered in wart-like glands, except for the caudal 20% of the body. Small, rounded rhabdites are present across the entire body. The proboscis hooks (15–16 μm) are bifurcate at the tip, forming a second, smaller hook of 5–6 μm. The muscular hook supports are 15–17 μm long. The pharynx measures 1/9 to 1/8 of the total body length and is connected to a spiny, elongated prepharyngeal cavity. The latter is three times longer than the pharynx. The single testis lies ventro-laterally to the pharynx and connects to a single seminal vesicle, which proximally empties into the copulatory bulb. Prostate glands enter the copulatory bulb at approximately the same place. The inverted-pear shaped copulatory bulb (49 µm) comprises the prostate vesicle and a spiny, 28-µm-long, arrow-like cirrus: proximally, the cirrus is 9 µm wide, it narrows to 4 µm at its midpoint, widens again to 12 µm subdistally and finally narrows to a distal, triangular tip. Cirrus spines are largest in the proximal end (7–9 µm) and distally decrease to 4–5 µm. The vitellarium extends from the pharynx to the copulatory bulb. A single, kidney-shaped ovary and globular bursa are positioned in the caudal body end. Oocytes are organised in a row and proximally decrease in diameter. A connection between the bursa and common atrium is visible., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 486, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1"]}

Cheliplana longissima n. sp. Gobert, Reygel & Artois Figs. 2F–H, 3D–E Etymology. The species epithet ‘longissima’ refers to the very long cirrus. Material examined. Holotype. PANAMA • 1 whole mount; Isla de Taboga, Playa de la Isla Taboga; 8°48’05”N, 79°33’16”W; 9 Dec. 2011; intertidal, medium fine to medium coarse sand from ripple marks in between Caulerpa and close to swash zone; KV.665. Other material. PANAMA • 3 whole mounts (incl. one juvenile specimen) and 3 serial sections; Isla de Taboga, Playa de la Isla Taboga; 8°48’05”N, 79°33’16”W; 9 Dec. 2011; intertidal, medium fine to medium coarse sand from ripple marks in between Caulerpa and close to swash zone; HU X.2.34–X.2.39. Description. Live specimens are transparent to slightly pink in colour.The body is 0.9–1.0 mm long, as measured on squeezed, whole-mounted specimens. A continuous haptic girdle is present at the caudal body-end (ag, Fig. 2H). The proboscis bears a pair of 15–23-μm-long (x = 19 μm, n = 4), curved hooks (h, Fig. 2G). The hook supports are relatively small, measuring 9–10 μm (hs, Fig. 2G). The mouth is situated a short distance behind the proboscis and is connected to the cylindrical pharynx through a long prepharyngeal tube (ph, ppc, Fig. 3E). The epithelium lining the inside of the tube is differentiated to form long, finger-like papillae lining the entire surface of the tube. These papillae do not appear to be sclerotised. Some diatom frustules were observed in the digestive tract. The common genital opening is situated in the posterior quarter of the body and is surrounded by glands (gl, gp, Fig. 2H). Two small, elongate seminal vesicles are provided with longitudinal muscles and enter the copulatory bulb proximally. The copulatory bulb (cb, Figs. 2H; 3D,E) is elongate and contains a prostatic vesicle in its proximal third (vg, Figs. 2H; 3D), followed distally by a long ejaculatory duct and a long, armed cirrus (ci, Figs. 2F,H; 3D,E). A thick layer of longitudinal muscles and circular muscles surrounds the copulatory bulb. The inside wall of the copulatory bulb shows a series of thin transverse crests on the dorsal side of the bulb (Fig. 2H). The interior surface is lined with a thin epithelium. The cirrus measures 235–365 μm (x = 300 μm, n = 2) and is armed with very fine spines (ci, Figs. 2F,H; 3D,E). In all available specimens, a characteristic loop was observed in the proximal part of the cirrus (ci, Figs. 2F,H; 3D). Distally, the cirrus ends in a short, sclerotised penis papilla (pp, Fig. 2F; 3D). The vaginal opening is located terminally and can be closed by a sphincter. It opens into an elongate vagina externa (ve, Fig. 2H), the distal end of which is surrounded by circular muscles. The vagina externa connects to the bursa, which is not muscular (b, Fig. 2H). The bursal lumen is lined with a pseudo-cuticular lining and surrounded by a thick, apparently syncytial parenchymatic tissue. The proximal end of the bursa is globular, nearly spherical, and lies adjacent to the single ovary, on the right-hand side of the body (ov, Fig. 2H). The quality of the sections did not allow study of any further details of the female system, such as a possible connection between the ovary and bursal complex and between the ovary and common genital atrium/gonopore. A number of conspicuous nuclei are present at the proximal end of the bursa (Fig. 2H).

Cheliplana canariensis Gobert, Reygel & Artois, 2017 Material examined. Reference material. The holotype, a whole-mounted specimen from Lanzarote (SMNH Type 8906). Known distribution. Lanzarote, Canary Islands, Spain (Gobert et al. 2017). Remarks. The specimen is rather small, with a total body length of 0.6 mm. The proboscis is ~42 μm long and carries 27–28-µm-long, curved hooks and ~18-μm-long hook supports. The paired seminal vesicles separately enter the proximal end of the copulatory apparatus. The copulatory bulb holds a proximal, prostatic bulb. Distally, the ejaculatory duct is differentiated into a 50-µm-long cirrus, armed with spines of varying length and thickness. The spines in the middle region of the cirrus are more robust and longer than those in the proximal and distal parts of the cirrus. A single ovary and large bursa are present near the caudal end of the body, but the organisation of the female system is not well known., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 466-467, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Gobert, S., Reygel, P. & Artois, T. (2017) Schizorhynchia (Platyhelminthes, Rhabdocoela) of Lanzarote (Canary Islands), with the description of eight new species. Marine Biodiversity, 49 (5), 2089 - 2107. https: // doi. org / 10.1007 / s 12526 - 017 - 0736 - x."]}

Cheliplana orthocirra Ax, 1959 Material examined. New material. ITALY • 1 whole mount; Sardinia, Asinara National Park, Cala del Bianco; 41°04’27”N, 8°20’12”E; 25 Sep. 2014; medium-grained sand between Posidonia sp., at 2.5 m deep; HU X.2.40. Note. No reference material was available to us at the time of this study. Known distribution. Florya, Sea of Marmara, Turkey (Ax 1959). Southern and Western Sweden (Atherton & Jondelius 2020). Remarks. The proboscis hooks are smooth, fairly straight and ~11 μm long in the specimen from Sardinia. Ax (1959) does not give any measurements except those pertaining to the cirrus. Cheliplana orthocirra has a pair of partially fused testes, positioned on one side of the pharynx. The copulatory bulb is positioned in the posterior half of the body and contains a proximal prostatic vesicle, which connects directly to the distal cirrus. A pair of large, globular seminal vesicles and prostatic glands enter the proximal end of the copulatory bulb. The cirrus is armed with very fine spines over its entire length. These spines decrease in size towards the distal end of the cirrus. A single gonopore and bursa are present near the caudal end of the specimen. In the specimen from Sardinia, the cirrus is 35 μm long, which is significantly shorter than the ~56 μm reported by Ax (1959). Nevertheless, given the cirrus shape and generally similar internal morphology, we feel confident in ascribing this specimen to C. orthocirra., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 475, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Ax, P. (1959) Zur Systematik, Okologie und Tiergeographie der Turbellarienfauna in den ponto-kaspischen Brackwassermeeren. Zoologische Jahrbucher Abteilung fur Systematik, Geographie und Biologie der Tiere, 87, 43 - 184.","Atherton, S. & Jondelius, U. (2020) Biodiversity between sand grains: Meiofauna composition across southern and western Sweden assessed by metabarcoding. Biodiversity Data Journal, 8, e 51813. https: // doi. org / 10.3897 / BDJ. 8. e 51813"]}

Cheliplana caeca Meixner, 1938 The name Cheliplana caeca was used by Meixner (1938) to refer to a species of Cheliplana with strongly curved proboscis hooks and a thick ‘cuticle’ lining the prepharyngeal tube. As noted by Marcus (1952), who refrained from including C. caeca in his key to Karkinorhynchidae, both the male and female genital structures are unknown, making it impossible to identify the species in the future. It is therefore considered a nomen nudum., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 486, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Meixner, J. (1938) Turbellaria (Strudelwurmer). Die Tierwelt der Nord- und Ostsee, 33, 1 - 146.","Marcus, E. (1952) Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo, 17, 5 - 188."]}

Cheliplana longissima n. sp. Gobert, Reygel & Artois Figs. 2F–H, 3D–E Etymology. The species epithet ‘longissima’ refers to the very long cirrus. Material examined. Holotype. PANAMA • 1 whole mount; Isla de Taboga, Playa de la Isla Taboga; 8°48’05”N, 79°33’16”W; 9 Dec. 2011; intertidal, medium fine to medium coarse sand from ripple marks in between Caulerpa and close to swash zone; KV.665. Other material. PANAMA • 3 whole mounts (incl. one juvenile specimen) and 3 serial sections; Isla de Taboga, Playa de la Isla Taboga; 8°48’05”N, 79°33’16”W; 9 Dec. 2011; intertidal, medium fine to medium coarse sand from ripple marks in between Caulerpa and close to swash zone; HU X.2.34–X.2.39. Description. Live specimens are transparent to slightly pink in colour.The body is 0.9–1.0 mm long, as measured on squeezed, whole-mounted specimens. A continuous haptic girdle is present at the caudal body-end (ag, Fig. 2H). The proboscis bears a pair of 15–23-μm-long (x = 19 μm, n = 4), curved hooks (h, Fig. 2G). The hook supports are relatively small, measuring 9–10 μm (hs, Fig. 2G). The mouth is situated a short distance behind the proboscis and is connected to the cylindrical pharynx through a long prepharyngeal tube (ph, ppc, Fig. 3E). The epithelium lining the inside of the tube is differentiated to form long, finger-like papillae lining the entire surface of the tube. These papillae do not appear to be sclerotised. Some diatom frustules were observed in the digestive tract. The common genital opening is situated in the posterior quarter of the body and is surrounded by glands (gl, gp, Fig. 2H). Two small, elongate seminal vesicles are provided with longitudinal muscles and enter the copulatory bulb proximally. The copulatory bulb (cb, Figs. 2H; 3D,E) is elongate and contains a prostatic vesicle in its proximal third (vg, Figs. 2H; 3D), followed distally by a long ejaculatory duct and a long, armed cirrus (ci, Figs. 2F,H; 3D,E). A thick layer of longitudinal muscles and circular muscles surrounds the copulatory bulb. The inside wall of the copulatory bulb shows a series of thin transverse crests on the dorsal side of the bulb (Fig. 2H). The interior surface is lined with a thin epithelium. The cirrus measures 235–365 μm (x = 300 μm, n = 2) and is armed with very fine spines (ci, Figs. 2F,H; 3D,E). In all available specimens, a characteristic loop was observed in the proximal part of the cirrus (ci, Figs. 2F,H; 3D). Distally, the cirrus ends in a short, sclerotised penis papilla (pp, Fig. 2F; 3D). The vaginal opening is located terminally and can be closed by a sphincter. It opens into an elongate vagina externa (ve, Fig. 2H), the distal end of which is surrounded by circular muscles. The vagina externa connects to the bursa, which is not muscular (b, Fig. 2H). The bursal lumen is lined with a pseudo-cuticular lining and surrounded by a thick, apparently syncytial parenchymatic tissue. The proximal end of the bursa is globular, nearly spherical, and lies adjacent to the single ovary, on the right-hand side of the body (ov, Fig. 2H). The quality of the sections did not allow study of any further details of the female system, such as a possible connection between the ovary and bursal complex and between the ovary and common genital atrium/gonopore. A number of conspicuous nuclei are present at the proximal end of the bursa (Fig. 2H)., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 463, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692

Cheliplana hypergyna Boaden, 1965 Material examined. New material. ITALY • observations and photographs of 1 live specimen; Sardinia, Asinara National Park, Punta Tumbarino; 41°02’17”N, 08°13’13”E; 29 Sep. 2014; coarse gravel with silt from a channel among rocks, at a depth of 29 m. FRANCE • 1 serially sectioned specimen; Banyuls-sur-Mer, Cap l’Abeille; 42°28’40”N, 3°09’19”E; 20 Jul. 2007; at the border between the coralligenous and sand zones, clean sand with some silt from a depth of 24 m; UH VIII.4.23 • 4 whole mounts, 8 serially sectioned specimens; Banyuls-sur-Mer, Le Troc, La Peleteuse; 42°28’42”N, 3°08’52”E; 31 Jul. 2007; at the transition of rocks to sandy substrate, clean sand from a depth of 15 m; UH VIII.4.11–VIII.4.22 • 4 whole mounts and 4 serially sectioned specimens; Banyuls-sur-Mer, Cap l’Abeille; 42°28’40”N, 3°09’19”E; 11 Jul. 2008; at the border between the coralligenous and sand zones, clean sand with some silt from a depth of 22 m; UH VIII.4.07–VIII.4.10 & UH VIII.4.24–VIII.4.27 • 1 whole mount; Cerbère, Les Chambres; 42°26’43”N, 3°10’09”E; 9 Jun. 2013; fine sand with a lot of silt; UH VIII.4.41. SPAIN • 4 whole mounts; Catalonia, Blanes; 41°40’04”N, 2°47’19”E; 20 Jul. 2012; sand patches on the north side of a rock with footpath, coarse, clean sand with organic debris; UH VIII.4.30–VIII.4.33. Known distribution. Porto Paone, Gulf of Naples, Italy (Boaden 1965). Archipel de Riou, Provence-Alpes-Côte d’Azur, France (Brunet 1968). Remarks. Our observations correspond to those of earlier authors (Boaden 1965; Brunet 1968). Live specimens measure up to 1.8 mm and have a slightly reddish pigmentation. The mouth is situated a short distance behind the proboscis. The proboscis is armed with a pair of slender hooks (15–16 μm) and bears a pair of thin, non-sclerotised sidepieces (12–13 μm). A single subterminal haptic girdle is present near the caudal body end. A single testis is present near the posterior end of the pharynx. From the testes, a pair of vasa deferentia leads to the paired seminal vesicles. Each seminal vesicle is 120–150 μm long. The seminal vesicles enter the proximal end of the male copulatory apparatus. The copulatory bulb contains a prostatic vesicle, 70–80 μm long, followed distally by a relatively short ejaculatory duct. The distal part of the ejaculatory duct is sclerotised to form an unarmed, tubular cirrus. Distally, the cirrus is provided with a number of fine, sclerotised ridges. According to Boaden (1965), only this part of the cirrus is eversible. A strongly muscular vagina externa is present in the posterior part of the body. It consists of a thin-walled canal, leading from the vaginal opening (shortly behind the common genital pore), to a thick-walled proximal section, which is divided into three chambers. Conspicuous radial striations are present on the vaginal wall in this part. Proximally, the vagina opens into a thin-walled bursa, which lies adjacent to the single ovary., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 473-474, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Boaden, P. J. S. (1965) A new interstitial turbellarian Cheliplana hypergyna n. sp. Pubblicazioni della Stazione Zoologica di Napoli, 34, 216 - 218.","Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana uruguayensis Van Steenkiste, Volonterio, Schockaert & Artois, 2008 Material examined. 2 whole mounts, including the holotype (HU IV.1.33; SMNH Type 7497) and 4 serially sectioned specimens (HU IV.1.34–IV.1.37) Known distribution. La Coronilla, Departamento de Rocha, Uruguay (Van Steenkiste et al. 2008). Remarks. Our observations and measurements correspond to those of Van Steenkiste et al. (2008). Van Steenkiste et al. (2008) report a maximum body length of 0.8 mm. A single testis is situated ventrally from the cylindrical pharynx. A pair of vasa deferentia connects the testis to the posterior body region, where the copulatory system is located. One vas deferens is thin-walled and widens distally to form a seminal vesicle; the other vas deferens is enlarged and surrounded by strong longitudinal muscles. The seminal vesicle and modified vas deferens enter the proximal end of the copulatory bulb together. The copulatory bulb consists of a proximal prostate vesicle, the ejaculatory duct and a very short, tubular stylet of ~11 μm long. The gonopore is situated in the caudal part of the body, at about 4/5 of the body length. The dorsally positioned ovary merges with a vitellarium, essentially forming an ovovitellarium. Bursal tissue connects the bursa to the ovary. A separate spermatic duct is absent. The bursa leads to a vagina externa with a thick, sclerotised wall. Where the vagina connects to the bursa, an elliptical seminal vesicle surrounded by circular muscles is present. The vaginal opening is situated anterior to the gonopore., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 484-485, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Van Steenkiste, N., Volonterio, O., Schockaert, E. & Artois, T. (2008) Marine Rhabdocoela (Platyhelminthes, Rhabditophora) from Uruguay, with the description of eight new species and two new genera. Zootaxa, 1914 (1), 1 - 33. https: // doi. org / 10.11646 / zootaxa. 1914.1.1"]}

Cheliplana evdonini Karling, 1983 Material examined. None. Known distribution. Tekslo Island, Hordaland Fylke, Norway (Karling 1983). Remarks (summarised from literature). The long prepharyngeal cavity is armed with spines. The proboscis bears a pair of 16-µm-long hooks.A pair of soft, terminally enlarged, rod-shaped sidepieces is present. Each sidepiece bears a single, long bristle. A single testis is situated alongside the pharynx and a single vas deferens connects the testis to an unpaired seminal vesicle, which has an elongated, winding shape. The copulatory bulb is ~60 μm long and 30 μm wide. Proximally, it contains a globular prostatic vesicle, which empties distally into the armed cirrus. Three parts can be distinguished on the cirrus: (1) a short, proximal, tubular part, ~20 μm long and armed with very small, hair-like spines; (2) a girdle with five hooks, each ~13 μm long; (3) a wider, distal, tube-like part, measuring ~23 μm and armed with fine hooks of ~4–8 μm. The bursa lies adjacent to the distal part of the cirrus. The vitellarium stretches out from the posterior end of the pharynx to the ovary. Karling (1983) mentions the excretory system, which is remarkably conspicuous compared to other schizorhynchs: he observed two lateral canals, which are interconnected through a transverse canal, located mid-body., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 471, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x"]}

Cheliplana pileola Jouk & De Vocht, 1989 Material examined. Reference material. The holotype (whole-mounted) specimen (SMNH Type 6981) and the 3 paratypes (two whole mounts and 1 serially sectioned specimen HU 145–147) from Kenya. 1 whole mount from South Africa (HU VII.4.07). Known distribution. Tudor Creek, Mombasa, Kenya (Jouk and De Vocht 1989). Sodwana Bay, Kwazulu-Natal, South Africa (Willems et al. 2017). Remarks. According to the description of Jouk and De Vocht (1989), specimens reach a total body length of 0.7–0.9 mm. Caudally, a single, continuous girdle of haptic glands is present. The pharynx is situated in the anterior third of the body. The prepharyngeal cavity is not armed with spines, though Jouk and De Vocht (1989) report cellular bodies with nuclei protruding above the epithelial surface of the prepharyngeal cavity. The proboscis is armed with a pair of smooth hooks (14–18 μm long) and has a pair of soft proboscis sidepieces, without sclerotised rods. The hook supports are 7–13 μm long. A pair of partially fused testes is present alongside and posterior to the pharynx. The male copulatory organ is present in the posterior 1/4. A pair of seminal vesicles enters the proximal end of the copulatory bulb, which contains a 25–30-µm-long prostatic vesicle, with a single type of secretion. The cirrus is 45–50 μm long and armed with sclerotised spines that somewhat increase in size towards the distal end. The distal end of the cirrus is surrounded by a sclerotic penis papilla of ~20 μm long. The copulatory bulb, as well as two glandular systems and a blind diverticulum empty into a male atrium. The single ovary is located alongside the male copulatory system. A large bursa lies alongside the ovary. The presence of a vagina externa could not be ascertained., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 477, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Jouk, P. E. H. & De Vocht, A. J. - P. (1989) Kalyptorhynchia (Plathelminthes Rahbdocoela) from the Kenyan Coast, with description of four new species. Tropical Zoology, 2, 145 - 157. https: // doi. org / 10.1080 / 03946975.1989.10539435.","Willems, W. R., Reygel, P., Van Steenkiste, N., Tessens, B. & Artois, T. J. (2017) Kalyptorhynchia (Platyhelminthes: Rhabdocoela) from KwaZulu-Natal (South Africa), with the description of six new species. Zootaxa, 4242 (3), 441 - 466. https: // doi. org / 10.11646 / zootaxa. 4242.3.2"]}

Cheliplana microcirrus Noldt, 1989 Material examined. None. Known distribution. Sylt, Germany (Noldt 1989). Remarks (summarised from literature). Live specimens are transparent and ~680 μm long. The proboscis has a pair of 12-µm-long, slender hook supports, which bear 11-µm-long proboscis hooks. Proboscis sidepieces are not present. The prepharyngeal cavity is unarmed. The pharynx is ~150 μm long and 70 μm in width. A single testis is situated adjacent to the pharynx. A pair of seminal vesicles, ~100 μm long and 25 μm wide, and a cluster of prostatic glands enter the proximal end of the copulatory bulb. Only one type of prostatic glands and secretion appears present. The entire copulatory bulb is ~68 μm long, with a diameter of 25–29 μm. The most distal end of the ejaculatory duct is widened to form a canal with folded, likely sclerotised walls. It continues into a symmetrically armed cirrus of ~12 μm, with spines measuring 1.5–2 μm. A single ovary is situated alongside the copulatory bulb. The vitellarium is unpaired and a bursa is located caudal to the gonopore. No sclerotised spermatic duct or vagina externa is present., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 475, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Noldt, U. (1989) Kalyptorhynchia (Plathelminthes) from sublittoral coastal areas near the island of Sylt (North Sea) I. Schizorhynchia. Microfauna Marina, 5, 7 - 85."]}

Cheliplana mauii n. sp. Gobert, Reygel & Artois Fig. 2D–E Etymology. The species epithet refers to the heroic trickster and demigod Mâui, who according to Polynesian mythology, hauled up the islands of the Hawaiian archipelago from the depths of the ocean. Material examined. Holotype. UNITED STATES • 1 whole mount; Hawaii, Oahu, Waimanalo Beach; 21°19’36”N, 157°40’59”W; 28 May 2010; medium coarse, very clean coral sand at a depth of ~ 2 m; KV.669. Other material. UNITED STATES • 1 whole mount; Hawaii, Oahu, Waimanalo Beach; 21°19’36”N, 157°40’59”W; 28 May 2010; medium coarse, very clean coral sand at a depth of ~ 2 m; HU X.2.05. Description. Live specimens are transparent to slightly pinkish in colour. The total body length measures ~ 0.75 mm (measured on a squeezed, whole-mounted specimen). Proboscis hook supports are 20–26 μm long (x = 23 μm, n = 2; hs, Fig. 2D) and bear a pair of robust, more or less straight proboscis hooks (h, Fig. 2D). These hooks are 28–36 μm long (x = 32 μm, n = 2). Proboscis sidepieces were not observed. The horizontal pharynx is situated in the anterior body half and connects to the mouth via a long, unarmed prepharyngeal cavity. The anterior edge of the pharynx bears a number of well-developed papillae. An unpaired testis is situated alongside and partly posterior to the pharynx. An unpaired seminal vesicle and long prostatic glands enter the proximal end of the male copulatory bulb. The proximal 2/3 of the bulb is taken up by the prostatic vesicle. Distally, the prostatic vesicle connects directly to a short cirrus (~9 μm; Fig. 2E) with a proximal diameter of ~15 μm and a distal diameter of ~7 μm. The distal edges of the cirrus fold backwards, forming a weakly sclerotised cap or papilla around the cirrus. Details of the female reproductive system could not be observed. A single ovary appears to be present adjacent to the male copulatory apparatus.

Cheliplana hiemalis Brunet, 1968 Material examined. Reference material. 1 whole mount (SMNH Type 2818) and 2 serially sectioned specimens (SMNH 82506–82507). Known distribution. Golfe de Marseille, France (Brunet 1968). Remarks. Our observations correspond to those of Brunet (1968). Live specimens are colourless and reach a total body length of ~ 1.3 mm. The proboscis is armed with a pair of 16–17-µm-long hooks. The proboscis sidepieces insert at the base of the muscular proboscis and each sidepiece bears a single 8-µm-long bristle. An unpaired testis is situated ventral to the pharynx. Vasa deferentia and seminal vesicles are paired, the latter entering the proximal part of the copulatory bulb separately. Within the copulatory bulb, the proximal prostatic vesicle is immediately followed by a weakly sclerotised ejaculatory duct, the most distal part of which widens to form a short, globular, 10–12-µmlong cirrus. According to Brunet (1968), the tubular sclerotised ejaculatory duct bears very fine sclerotised spines. While re-examining the type material, however, we did not observe such spines., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 473, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana santiaguera Diez, Reygel & Artois, 2019 Material examined. None. Known distribution. Siboney, Cuba (Diez et al. 2019). Remarks (summarised from literature). Specimens are pinkish and are 0.7–0.8mm long when whole mounted. The proboscis carries 16-µm-long, curved hooks. Hook supports are 6 to 8 µm long. The pharynx measures 124- 126 µm, corresponding to 1/8 of the total body length, and connects to the mouth through a twice as long, spiny prepharyngeal cavity. The copulatory bulb is inverted-pear shaped (50–74 µm) and comprises the prostate vesicle and spiny cirrus (22–28 µm, spines 0.5 µm). A sphincter occurs in the middle of the ejaculatory duct. The vitellarium extends from the pharynx to the copulatory bulb. A single bursa and ovary occur caudally. Oocytes lie in a row and proximally diminish in diameter. The bursa is connected to the common atrium and opens externally through a vagina, posterior to the common gonopore., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 479-480, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1"]}

Cheliplana cubana n. sp. Diez, Gobert, Reygel & Artois Fig. 1C–E Etymology. Species epithet refers to the island of Cuba, where the species was found. Material examined. Holotype. CUBA • 1 whole mount; Holguín province, Gibara municipality, Bahía de Gibara; 17 Feb. 2016; sublittoral, to a depth of up to 0.4 m, sandy bottom with many seashell fragments and organic material, salinity 32‰; KV.634. Other material. CUBA • 5 whole mounts; Holguín province, Gibara municipality, Bahía de Gibara; 17 Feb. 2016; sublittoral, to a depth of up to 0.4 m, sandy bottom with many seashell fragments and organic material, salinity 32‰; X.3.21–X.3.25 • 15 whole mounts; Holguín province, Banes municipality, Guardalavaca; 28 Feb. 2017; intertidal, superficial fine sand around roots of Avicennia germinans, salinity 35‰; HU X.2.08–X.2.22 • 3 whole mounts; Holguín province, Banes municipality, Macabi; sublittoral fine sand, 0.3 m deep, salinity 34‰; HU X.2.23–X.2.25. Description. Whole-mounted specimens are 0.6–1.6 mm (x = 0.9 mm; n = 16) long. The body is unpigmented, transparent. The proboscis (p, Fig. 1C) has a pair of small, curved hooks measuring 10–19 µm (x = 15 µm, n = 8), each with a dilated base and pointy tip. Hook supports are ~ 11 µm long. The pharynx bulb is relatively small and measures approximately 1/9 of the total body length (ph, Fig. 1C). The anterior edge of the pharynx bulb bears a number of anteriorly projecting papillae. The mouth is situated behind the proboscis and connects to the pharynx bulb via a long, unarmed, oral tube (ppc, Fig. 1C). The common genital opening, situated anterior to the haptic girdle at approximately 7/8 of the body length, is surrounded by clusters of glands that are conspicuous in live specimens. One large testis is located in the anterior half of the body, posterior to the pharynx (t, Fig. 1C). The male copulatory organ is situated in the posterior part of the body. A pair of elongated seminal vesicles enter the proximal end of the copulatory bulb separately (vs, Fig. 1C). A small prostatic vesicle occupies the proximal part of the copulatory bulb (vg, Fig. 1C). The tubular cirrus is 117–173 µm long (x = 152 μm, n = 21), with the distal part forming a U-shaped bend (ci, Fig. 1C; Fig. 1D–E). The cirrus is armed with small spines over its entire length, though only the distal end was observed to be eversible. Few details of the female system could be observed: aAsingle ovary is present near the caudal end of the body (ov, Fig. 1C). A large, vacuolated bursa is situated beside the male copulatory bulb (b, Fig. 1C)., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 458-459, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692

Cheliplana subproximalis Diez, Reygel & Artois, 2019 Material examined. None. Known distribution. Bueycabón and Las Sardinas, Cuba (Diez et al. 2019). Remarks (summarised from literature). Live specimens are pinkish, translucent and rather small: The body length is 0.4–0.7 mm, as measured on whole mounts. The proboscis is armed with 13–18-µm-long, curved hooks. The muscular hook supports measure 5–8 µm. The pharynx measures 1/7 to 1/8 of the total body length in live specimens. The spiny prepharyngeal cavity is elongated, measuring twice as long as the pharynx. The mouth opens antero-ventrally and subterminally. The single testis lies postero-laterally to the pharynx and connects to paired seminal vesicles. Distally, the two seminal vesicles fuse into a short, seminal duct, which opens into the copulatory bulb. Two proximal ducts of unknown origin enter the prostate vesicle near the entrance of the seminal duct. The 62–66-µm-long cirrus is armed with fine spines. Distally, the cirrus is slightly widened and surrounded by an asymmetric sclerotised cap (10–20 µm x 6–10 µm). Cirrus spines measure 2–3 µm in this region. The vitellarium extends from the pharynx to the copulatory bulb. A single, kidney-shaped ovary is present. Oocytes occur in a row and proximally decrease in diameter. The bursa lies caudally from the common gonopore., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 482-483, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1"]}

Cheliplana asinaraensis n. sp. Gobert, Reygel & Artois Fig. 1A–B Etymology. The species epithet ‘asinaraensis’ refers to the National Park of Asinara (Sardinia, Italy), where the specimen was found. Material examined. Holotype. ITALY • 1 whole mount; Punta Tumbarino, Asinara National Park, Sardinia; 41°02’17”N, 08°13’13”E; 29 Sep. 2014; 29 m depth, coarse gravel with silt from a channel among rocks; KV.633. Description. The specimen is ~ 1.5 mm long, transparent and colourless. The proboscis is large, with an overall length of ~50 μm (p, Fig. 1A). The hook supports measure ~20–22 μm, and the smooth, evenly curved proboscis hooks measure ~38 μm. The mouth is situated ventrally, posterior to the proboscis, and is connected to the pharynx via a long, unarmed oral tube. The anterior edge of the pharynx is lined with papillae. A single testis is positioned alongside the pharynx (t, Fig. 1A). The common genital opening is situated in the posterior 1/5 of the body and is surrounded by glands (gp, Fig. 1A). The atrial organs of the male and female genital system surround the gonopore. The male copulatory system consists of a pair of relatively large seminal vesicles (vs, Fig. 1A), which enter the elongate copulatory bulb proximally. At the same location, a large group of prostatic glands enter the bulb and form a prostatic vesicle in the proximal half of the copulatory bulb (pg, Fig. 1A). The distal half of the ejaculatory duct forms a sclerotised cirrus with an overall length of 60 μm (ci, Fig. 1A; Fig. 1B). The cirrus consists of two clearly defined regions (Fig. 1B). The proximal part is a sclerotised, straight tube, which shows a longitudinal striation. Towards the distal end of this part, fine triangular spines are present. The distal, 18- μm-long part of the cirrus is crescent-shaped and eccentrically curved. The outer part of the crescent is armed with very fine, bristle-like spines, while in the central part, large, but thin lamellae are present. A large ovary is positioned adjacent to the male copulatory system (ov, Fig. 1A). An oviduct or ductus communis could not be observed. A vaginal opening is situated medioventrally, directly anterior to the adhesive girdle. The vagina externa is surrounded by longitudinal or diagonal muscles. Circular muscles may be present as well, but this was impossible to ascertain from the whole-mounted specimen. A constriction separates the vagina from a large, sac-like bursa (b, Fig. 1A). The proximal end of the bursa shows a small, globular part, provided with a small, funnel-shaped spermatic duct.

Cheliplana deverticula Ax, 2008 Fig. 6D–F Synonyms. Cheliplana triductibus Van Steenkiste, Volonterio, Schockaert & Artois, 2008 Material examined. New material. PORTUGAL • 1 whole mount; Algarve, Olhão; 37°01’34”N, 7°50’56”W; 13 Sep. 2011; mid-eulittoral zone at low tide, fine sand and silt from an oxygen-poor sediment layer with organic detritus at about 5 cm below the surface; HU X.2.43 • 1 whole mount and 3 serial sections; Algarve, Olhão; 37°01’34”N, 7°50’56”W; 13 Sep. 2011; high eulittoral at low tide, very coarse shell gravel, mixed with coarse sand, organic detritus and silt in tidal gully; HU X.2.44–X.2.47. Reference material. 1 whole mount (holotype, SMNH Type 7496) and 4 serially sectioned specimens (HU IV.1.29–IV.1.32) from Uruguay. Known distribution. Bay of Arcachon, France (Ax 2008). Playa Ramirez, Departamento de Montevideo, Uruguay (Van Steenkiste et al. 2008). Remarks. The newly collected specimens from the Algarve are colourless. A single haptic girdle is present near the caudal body end. A cylindrical pharynx is situated in the anterior half of the body and connected to the mouth through a long, unarmed prepharyngeal cavity. The mouth is situated anteriorly, closely behind the proboscis. A single, unpaired testis is positioned alongside the pharynx. The proboscis is armed with a pair of smooth hooks. A pair of soft proboscis sidepieces is present, each bearing bristles. A pair of pear-shaped seminal vesicles (vs, Fig. 6E) connects via a pair of vasa deferentia to the distal end of the copulatory bulb (cb, Fig. 6E). The copulatory bulb contains a granular vesicle proximally (vg, Fig. 6E) and an armed cirrus distally (Fig. 6D; ci, Fig. 6E). In the Portuguese specimens, the cirrus measures 71–79 μm (n = 2). In addition to the cirrus, a small, blind-ending accessory cirrus is present at the distal end of the copulatory bulb (ac, Fig. 6D,E). The accessory cirrus measures 21–27 μm (n = 2) and is lined with spines identical to those of the cirrus (ac, Fig. 6D). The female reproductive system exhibits a number of characteristic features: a large bursa lies caudally from the ovary (b, ov, Fig. 6F). The anterior part of the bursa has three sperm-containing compartments, from each of which a slender, sclerotised spermatic duct leads to the ovary (x, Fig. 6F). The three ducts are wound tightly around each other. The bursa is connected to a long vagina externa. Ax (2008) described Cheliplana deverticula based on the cirrus morphology and proboscis hooks, without reference to the female system. Van Steenkiste et al. (2008) retrieved a number of morphologically similar specimens from Uruguay and provisionally described these as Cheliplana triductibus, pending additional information on the anatomy of the female system in C. deverticula. The new specimens from Portugal now allow investigation of the female genital system, which appears to be identical to that described for C. triductibus. Furthermore, the measurements of the male copulatory organs and proboscis hooks are also in the same size range as reported for both C. triductibus and C. deverticula. Considering the publication dates of Ax (2008) and Van Steenkiste et al. (2008) (February and October, respectively), C. triductibus is considered a junior synonym of C. deverticula (International Code on Zoological Nomenclature 2015). Some minor differences were observed between the Portuguese and Uruguayan populations. The degree of sclerotisation of the spermatic ducts appears more extensive in the Portuguese specimens compared to the specimens from Uruguay. Furthermore, in the Portuguese specimens, a single cell nucleus is visible in the widened proximal part of the funnel-shaped ducts. As these observations may be attributed to either quality variations of the preserved material or intraspecific variation, we deem these differences insufficient to consider C. deverticula and C. triductibus separate species., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 468, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Ax, P. (2008) Plathelminthes aus Brackgewassern der Nordhalbkugel. Abhandlungen der Mathematisch-naturwissenschaftlichen Klasse, Jahrgang 2008, 1. Akademie der Wissenschaften und der Literatur, Mainz, Franz Steiner Verlag, 696 pp.","Van Steenkiste, N., Volonterio, O., Schockaert, E. & Artois, T. (2008) Marine Rhabdocoela (Platyhelminthes, Rhabditophora) from Uruguay, with the description of eight new species and two new genera. Zootaxa, 1914 (1), 1 - 33. https: // doi. org / 10.11646 / zootaxa. 1914.1.1","International Commission on Zoological Nomenclature (2015) International Code of Zoological Nomenclature. 4 th Edition. International Trust for Zoological Nomenclature, London, 306 pp."]}

Cheliplana curvocirro Schilke, 1970 Material examined. New material. FRANCE • 1 whole mount; Wimereux, near the marine station of the University of Lille; 50°45’48”N, 1°36’11”E; 15 Sep. 2015; fine sand and shell gravel on rocks; HU X.3.12 • 5 whole mounts; Wimereux, 100 m in front of the marine station of the University of Lille; 50°45’48”N, 1°36’11”E; 16 Sep. 2015; upper 0.2 m of sand with organic matter and algae; HU X.3.13–X.3.17 • 1 whole mount; Wimereux, beach 70 m in front of the cliff south of Wimereux; 16 Sep. 2015; sand and shell gravel between algae; X.3.18. Note. No reference material was available to us at the time of this study. Known distribution. Amrum and Sylt, Germany (Schilke, 1970; Hellwig 1987; Wehrenberg & Reise 1985). Römö, Denmark (Wehrenberg & Reise 1985). Remarks. Our observations largely correspond to those of Schilke (1970). The most important characteristics are listed here. Live specimens are white-grey in colour and 0.6–1.0 mm (x = 0.8 mm, n = 4) long. A single caudal haptic girdle is present. The muscular proboscis hook supports (18–19 μm) carry a pair of 10–13-µm-long, curved hooks. Proboscis hooks in our specimens are slightly larger (10–16 μm, x = 13 μm, n = 7) than what was reported by Schilke (1970) (10–13 µm). The prepharyngeal lumen is not lined with spines. A single testis is present, either anterior or posterior to the pharynx. Seminal vesicles are ~40 μm long and proximally enter the copulatory bulb. The copulatory bulb measures 96–100 μm (x = 102 μm, n = 7) in our newly collected specimens, falling well within the size range of 90–110 μm reported in literature. Along with the seminal vesicles, a number of prostatic glands enter the bulb. Inside the copulatory bulb, a U-shaped bend at the midpoint of the ejaculatory duct was observed in all newly collected specimens. Distally, the ejaculatory duct forms a long cirrus (70–90 μm). In the proximal part of the cirrus, fine lines and points are visible, which may be very small, fine spines. More distally, the cirrus is armed with conspicuous spines, increasing in size towards the distal end of the cirrus. The sclerotised wall of the distal cirrus end folds over to form a penis papilla. Schilke (1970) reports a papilla of 5–7 μm, similar to the 6–8 μm range measured in the newly obtained specimens (x = 7 μm, n = 3)., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 467, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Schilke, K. (1970) Kalyptorhynchia (Turbellaria) aus dem Eulitoral der deutschen Nordseekuste. Helgolander wissenschaftliche Meeresuntersuchungen, 21, 143 - 265. https: // doi. org / 10.1007 / BF 01630522","Hellwig, M. (1987) Oekologie freilebender Plathelminthen im Grenzraum Watt-Salzwiese lenitischer Gezeitenkusten. Microfauna Marina, 3, 157 - 244.","Wehrenberg C. & Reise, K. (1985) Artenspektrum und Abundanz freilebender Plathelminthes in sublitoralen Sanden der Nordsee bei Sylt. Microfauna Marina, 2, 163 - 180."]}

Cheliplana hawaiiensis n. sp. Gobert, Reygel, Van Steenkiste & Artois Fig. 2A–C, Fig. 3A–C, Fig. 4 Etymology. The species epithet refers to the Hawaiian archipelago, where the species was first found. Material examined. Holotype. UNITED STATES • 1 whole mount; Hawaii, Oahu, Waimanalo Beach; 21°19’36”N, 157°40’59”W; 31 May 2010; intertidal zone, fine sand with organic detritus among blocks of coral; KV.635. Other material. UNITED STATES • 6 whole mounts and two serial sections; Hawaii, Oahu, Waimanalo Beach; 21°19’36”N, 157°40’59”W; 31 May 2010; intertidal zone, fine sand with organic detritus among blocks of coral; HU X.2.26–X.2.33. CANADA • 3 whole mounts; British Columbia, Calvert Island, West Beach; 51°39’24”N, 128°08’41”W; 3 Jun. 2015; intertidal zone, medium-grained sand from the beach surface; MI4186–MI4188 • 3 whole mounts; British Columbia, Calvert Island, North Beach; 51°39’52”N, 128°08’46”W; 7 Jun. 2017; coarse sand in lower intertidal; MI4189–MI4191 • 1 whole mount; British Columbia, Calvert Island, Foggy Cove; 51°39’07”N, 128°08’32”W; 9 Apr. 2016; medium-grained sand in between boulders in the lower intertidal; MI4192. Description. Specimens are largely transparent, with a weak brown to orange colouration (Figs. 3A, 4A). A caudal haptic girdle is present (ag, Fig. 2A). The proboscis of the Hawaiian specimens is ~37 μm long with 18-μmlong muscular hook supports and a pair of smooth proboscis hooks ~20 μm long (h, hs, Fig. 3B). The proboscis of the Canadian specimens is about 28 μm long with 10-μm-long hook supports and 18 μm long hooks (h, hs, Fig. 4B; 4D). The proboscis sidepieces are straight, non-sclerotised rods, with enlarged distal ends, bearing a single bristle (sp, Figs. 3B; 4B). The mouth is situated directly posterior to the proboscis. The pharynx is positioned in the anterior part of the body (ph, Figs. 2A; 3A; 4A) and connects to the mouth via a long, slender oral cavity lined with spines (ppc, Fig. 2A; 4A). The anterior edge of the pharynx is lined with papillae. In some specimens, the body contains large numbers of diatom frustules. A single testis is present in the anterior body half, just behind and/or alongside the pharynx (t, Fig. 2A; 3A; 4A). The posterior part of the testis shows a globular accumulation of sperm, probably corresponding to the area where the testis connects to the vas deferens. The male copulatory bulb measures ~117 μm in the Hawaiian specimens (cb, Fig. 3A) and 75–100 µm in the Canadian specimens (cb, Fig. 4A,C,E). Two seminal vesicles enter the copulatory bulb proximally (vs, Figs. 2A; 4A,C). The copulatory bulb is of the conjuncta duplex type (Karling 1956) and is surrounded by a sheath of longitudinal muscles. The presence of circular muscles surrounding the copulatory bulb could not be determined. The large prostatic glands also enter the copulatory bulb proximally and form a prostatic vesicle in the proximal part of the bulb (pg, vg, Figs. 2A; 3A; 4A,C). The distal part of the bulb holds the ejaculatory duct, the distal end of which forms an armed cirrus (Figs. 2C; 3C; ci, Figs. 2A; 3A; 4A,C,E) measuring 30–40 μm (Canada) or 41–68 μm (Hawaii). The cirrus is differentiated in three distinct regions (Figs. 2C; 4E): the most proximal part is tubular, with a length of 15–31 μm (x = 21 μm, n = 6; Hawaii) or 12–18 μm (x = 15 μm, n = 7; Canada) and a diameter of 8–16 μm (x = 12 μm, n = 6; Hawaii) or 7–9 μm (x = 8 μm, n = 7; Canada). This part is armed with very fine spines with a rectangular base. This proximal tube is followed distally by a ring of six long, curved spines of ~12 μm long (measured on Canadian specimens), each set in sclerotised pockets. The most distal region is 23–34 μm (x = 27 μm, n = 6; Hawaii) or 12–17 μm (x = 15 μm, n = 7; Canada) long, with a diameter of ~17–26 μm (x = 22 μm, n = 6; Hawaii) or 12–17 μm (x = 14 μm, n = 7; Canada). This distal part is lined with densely stacked, bristle-like spines with a length of ~8 μm (Hawaii) or ~5 μm (Canada). A single, large ovary is present near the copulatory apparatus (ov, Fig. 4A). A bursa is situated posterior to the common genital opening (b, Fig. 4A,C). No spermatic duct or vagina externa were observed.

Cheliplana cubana n. sp. Diez, Gobert, Reygel & Artois Fig. 1C–E Etymology. Species epithet refers to the island of Cuba, where the species was found. Material examined. Holotype. CUBA • 1 whole mount; Holguín province, Gibara municipality, Bahía de Gibara; 17 Feb. 2016; sublittoral, to a depth of up to 0.4 m, sandy bottom with many seashell fragments and organic material, salinity 32‰; KV.634. Other material. CUBA • 5 whole mounts; Holguín province, Gibara municipality, Bahía de Gibara; 17 Feb. 2016; sublittoral, to a depth of up to 0.4 m, sandy bottom with many seashell fragments and organic material, salinity 32‰; X.3.21–X.3.25 • 15 whole mounts; Holguín province, Banes municipality, Guardalavaca; 28 Feb. 2017; intertidal, superficial fine sand around roots of Avicennia germinans, salinity 35‰; HU X.2.08–X.2.22 • 3 whole mounts; Holguín province, Banes municipality, Macabi; sublittoral fine sand, 0.3 m deep, salinity 34‰; HU X.2.23–X.2.25. Description. Whole-mounted specimens are 0.6–1.6 mm (x = 0.9 mm; n = 16) long. The body is unpigmented, transparent. The proboscis (p, Fig. 1C) has a pair of small, curved hooks measuring 10–19 µm (x = 15 µm, n = 8), each with a dilated base and pointy tip. Hook supports are ~ 11 µm long. The pharynx bulb is relatively small and measures approximately 1/9 of the total body length (ph, Fig. 1C). The anterior edge of the pharynx bulb bears a number of anteriorly projecting papillae. The mouth is situated behind the proboscis and connects to the pharynx bulb via a long, unarmed, oral tube (ppc, Fig. 1C). The common genital opening, situated anterior to the haptic girdle at approximately 7/8 of the body length, is surrounded by clusters of glands that are conspicuous in live specimens. One large testis is located in the anterior half of the body, posterior to the pharynx (t, Fig. 1C). The male copulatory organ is situated in the posterior part of the body. A pair of elongated seminal vesicles enter the proximal end of the copulatory bulb separately (vs, Fig. 1C). A small prostatic vesicle occupies the proximal part of the copulatory bulb (vg, Fig. 1C). The tubular cirrus is 117–173 µm long (x = 152 μm, n = 21), with the distal part forming a U-shaped bend (ci, Fig. 1C; Fig. 1D–E). The cirrus is armed with small spines over its entire length, though only the distal end was observed to be eversible. Few details of the female system could be observed: aAsingle ovary is present near the caudal end of the body (ov, Fig. 1C). A large, vacuolated bursa is situated beside the male copulatory bulb (b, Fig. 1C).

Cheliplana pacifica Noldt & Hoxhold, 1984 Material examined. Reference material. 10 serially sectioned specimens, including the holotype (P1851– P1860). Known distribution. Galápagos archipelago, Ecuador (Noldt & Hoxhold 1984). Remarks. Our observations correspond to those of Noldt & Hoxhold (1984). Specimens are 0.6 to 1.6 mm long. The body is not pigmented. A single, continuous haptic girdle is present near the caudal body end. The overall length of the proboscis is 22–38 μm, with 9–16-µm-long hook supports and slightly curved, 13–22-µm-long sclerotised hooks. Proboscis sidepieces have fine bristles. The oral cavity is lined with a thin, eosinophilic epithelium, partially transformed into sclerotised spines.A single testis is situated ventro-laterally alongside the pharynx. Seminal vesicles are 100–140 μm long and are surrounded by longitudinal muscles. The seminal vesicles and prostatic glands enter the 220–270-µm-long copulatory bulb proximally. The prostatic bulb, situated in the proximal part of the copulatory bulb, contains two distinct types of gland secretion and is surrounded by a separate layer of longitudinal muscles. The ejaculatory duct is partially sclerotised and widens distally to form a cirrus of ~50–60 μm long, provided with fine, 1–2-µm-long spines. Distally, the sclerotised cirrus wall is folded to form a 25–40-µm-long penis papilla. A sphincter is present in front of the insertion of the sclerotised cap. Two clusters of glands surround the common genital atrium: ventrally, around the common genital opening, a cluster of coarse-grained, basophilic glands, and more proximally, a cluster of fine-grained, eosinophilic glands. The female genital canal is short and connects the single ovary to the common genital atrium. The opening to the vagina externa is situated terminally. The distalmost part of the vagina forms a small bulbous region, which was not mentioned by Noldt & Hoxhold (1984), but was easily distinguished in the holotype. The vaginal pore is provided with a strong sphincter. The vagina externa leads into a long, sinuous bursa, which is made up of a mass of syncytial, parenchymatic tissue. A short, sclerotised spermatic duct is present between the bursa and ovary. Noldt & Hoxhold (1984) mention a distinct difference in size, related to the locality where the specimens were found. The specimens from the type locality (Bahía Darwin) were consistently larger than the specimens from the Santa Cruz locality (total body length: 1.3–1.6 μm vs 0.6–0.9 μm respectively). The proboscis and copulatory organ show a similar variation in size., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 476, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Noldt, U. & Hoxhold, S. (1984) Interstitielle Fauna von Galapagos. XXXIV. Schizorhynchia (Plathelminthes, Kalyptorhynchia). Microfauna Marina, 1, 199 - 256."]}

Cheliplana boadeni Schilke, 1970 Fig. 6A–C Material examined. New material. GERMANY • 1 whole mount; Sylt, List; 55°00’56”N, 8°26’12”E; 19 Aug. 2015; coarse sediment in the upper eulittoral zone, sediment taken by digging down to the water table at low tide; HU X.3.19 • 1 whole mount; Sylt, List; 55°00’56”N, 8°26’12”E; 19 Aug. 2015; spot with algae at breakwater, with somewhat coarser sediment than the surrounding mud; HU X.3.20. Note. No reference material was available to us at the time of this study. Known distribution. Sylt, Germany (Schilke 1970; Hoxhold 1974; Scherer 1985; Noldt 1989). Traeth Bychan, Wales, United Kingdom (Boaden 1963). Remarks. Boaden (1963) collected a specimen in Wales (United Kingdom), to which he referred as Rhinepera sp. It has an unpaired ovary and testis and resembles C. remanei except for the presence of a striated, plate-like stylet instead of a cirrus. Schilke (1970) noted that this was likely a specimen of C. boadeni. Based on Boaden’s drawings and description, we are inclined to agree with Schilke’s assessment. Boaden (1963) and Schilke (1970) report a total body length of ~ 1.5 mm. The new specimens are slightly smaller, measuring 0.7 and 1.2 mm. The single caudal haptic girdle is ochre coloured and sharply delineated. The proboscis of specimens collected by Schilke (1970) are characterised by 18–21-µm-long hooks, 23-µm-long hook supports and 24-µm-long sidepieces (sp, Fig. 6C). Newly collected specimens from Sylt bear hooks of 20–27 μm long (h, Fig. 6C). The oral cavity is armed with 5 rows of spines. The paired testes are positioned in front of and alongside the pharynx. Anterior to the pharynx, a connection between the testes is present. The male copulatory apparatus measures 80–130 μm and is situated in the posterior body third. The copulatory bulb consists of a globular proximal region, which contains a globular prostatic vesicle, and a more narrow, cylindrical distal part, in which the sclerotised copulatory structures are situated (Fig. 6A–B). The prostatic vesicle measures 62 μm by 44 μm. The sclerotised parts are described as a complex, double-walled stylet by Schilke (1970), whereas Hoxhold (1989) describes them as consisting of a 45–50-µm-long stylet with a spirally folded proximal part, surrounded by a sheathlike, ridged, 56–63-µm-long cirrus. The latter is diagonally striated in its proximal part and longitudinally striated in its distal one. Following Hoxhold’s terminology, as we did in our Fig. 6A, and in the identification key (see further), the inner part is the stylet proper, more or less hourglass shaped in the new specimen, while the outer striated part is the cirrus (ci, st, Fig. 6A). The entire sclerotised system of the new specimens measures ~54 μm, which is well within the size range reported by Schilke (1970) (50–60 μm). It has a basal width of ~20 μm. The diagonal striation of the cirrus mentioned by Hoxhold (1989) was not observed in the new specimen. The single ovary is in direct contact with the vitellarium. A vagina externa is present and opens into a large, undivided bursa., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 465-466, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Schilke, K. (1970) Kalyptorhynchia (Turbellaria) aus dem Eulitoral der deutschen Nordseekuste. Helgolander wissenschaftliche Meeresuntersuchungen, 21, 143 - 265. https: // doi. org / 10.1007 / BF 01630522","Hoxhold, S. (1974) Zur Populationsstruktur undAbundanzdynamik interstitieller Kalyptorhynchia (Turbellaria, Neorhabdocoela). Mikrofauna des Meeresbodens, 41, 1 - 34.","Scherer, B. (1985) Annual dynamics of a meiofauna community from the \" sulfide layer \" of a North Sea sand flat. Microfauna Marina, 2, 117 - 162.","Noldt, U. (1989) Kalyptorhynchia (Plathelminthes) from sublittoral coastal areas near the island of Sylt (North Sea) I. Schizorhynchia. Microfauna Marina, 5, 7 - 85.","Boaden, P. J. S. (1963) The interstitial Turbellaria Kalyptorhynchia from some North Wales beaches. Proceedings of the Zoological Society, London, 141 (1), 173 - 205. https: // doi. org / 10.1111 / j. 1469 - 7998.1963. tb 01608. x"]}

Cheliplana piriformis Brunet, 1968 Material examined. Reference material. 1 whole-mounted specimen (SMNH 52821) and 2 serially sectioned specimens (SMNH Type 2819, SMNH 82508). Known distribution. Golfe de Marseille, France (Brunet 1968). Remarks. Our observations correspond to those of Brunet (1968). Live specimens are colourless and measure 1–1.2 mm. The proboscis is armed with a pair of slightly curved hooks, 13–14 μm long. A pair of soft proboscis sidepieces is present, each bearing a single, thick bristle. A single testis is situated alongside or directly posterior to the pharynx. The paired seminal vesicles are surrounded by longitudinal muscles and lead into the proximal end of the ‘club-shaped’ copulatory bulb. The copulatory bulb is surrounded by a thick layer of longitudinal muscles. The ejaculatory duct runs axially through the copulatory bulb and displays a series of widened sections. These sections appear as two to four ‘chambers’ and decrease in size towards the distal end of the bulb, where the ejaculatory duct forms an eversible, piriform cirrus, armed with small spines (~1 μm)., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 477, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana sarnensis Gobert, Reygel & Artois, 2017 Material examined. Reference material. The holotype (SMNH Type 8907) and 4 whole mounts and 4 serially sectioned specimens from Lanzarote (HU VII.4.45–VIII.1.02). Known distribution. Lanzarote, Canary Islands, Spain (Gobert et al. 2017). Remarks. The caudal region of Cheliplana sarnensis is very extensible, similar to the situation in C. varicauda. As such, the overall body length depends on the state of contraction. The proboscis is provided with a pair of curved, 13–20-µm-long proboscis hooks, without denticles. The hook supports are small, only 7 μm long. The male genital apparatus has a single functional seminal vesicle. The copulatory bulb contains a proximal prostate vesicle and, more distally, an ~84-µm-long sclerotised ejaculatory duct. The distal part of the ejaculatory duct is transformed in a ~42-µm-long cirrus armed with very fine spines of uniform length. The vagina externa and bursa are connected to the ovary through three intertwined, funnel-shaped, sclerotised spermatic ducts., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 480, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Gobert, S., Reygel, P. & Artois, T. (2017) Schizorhynchia (Platyhelminthes, Rhabdocoela) of Lanzarote (Canary Islands), with the description of eight new species. Marine Biodiversity, 49 (5), 2089 - 2107. https: // doi. org / 10.1007 / s 12526 - 017 - 0736 - x."]}

Cheliplana vaginalis Karling, 1983 Synonyms. Rhinepera vaginalis nomen nudum Meixner, 1929. Material examined. None. Known distribution. Bay of Kiel, Germany (Meixner 1938 in Karling 1983). Remarks (summarised from literature). The most important morphological characteristics of the species are described by Karling (1983). Live specimens measure 0.8 mm. The proboscis hooks are ~18 μm long. The prepharyngeal lumen is long and armed with spines, which, according to Meixner (unpublished notes quoted in Karling 1983), are strongly developed in the dorsal part and less in the ventral part. Karling (1983) describes the pharyngeal spines as ‘soft, plasmatic tufts’. A single, continuous haptic girdle is present near the caudal body end. A single testis is situated ventrally, posterior to the pharynx. The common genital opening and vaginal opening are located in front of the haptic girdle. The male copulatory bulb is tubiform, with a widened, proximal part containing the prostatic vesicle. A pair of seminal vesicles enters at the proximal end of the bulb. The cirrus is long and tubular and ornamented with longitudinal, sclerotised ridges. Distally, it ends in a small penis papilla, which protrudes into the tubiform male atrium. The male atrium connects to the common genital atrium. The vaginal opening is situated between the common genital opening and the haptic girdle. The vagina externa is a long, winding tube, lined with a thick and sclerotised basal lamina (pseudocuticula).A syncytial sheath and a single layer of circular muscles surround the vagina. A small bulb containing a number of cell nuclei is present where the tubular vagina connects to the non-muscular, syncytial bursa. A cytoplasmic bulb, which is somewhat separate from the bursa itself, connects directly to the ovary. No spermatic duct appears present., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 485, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x","Meixner, J. (1929) Morphologisch-okologische Studien an neuen Turbellarien aus dem Meeressande der Kieler Bucht. Zeitschrift fur Morphologie und Okologie der Tiere, 14, 765 - 791. https: // doi. org / 10.1007 / BF 00419332","Meixner, J. (1938) Turbellaria (Strudelwurmer). Die Tierwelt der Nord- und Ostsee, 33, 1 - 146."]}

Cheliplana euxeinos Ax, 1959 Material examined. None. Known distribution. Sile, Black Sea, Turkey (Ax 1959). Agigea, Black Sea, Romania (Mack-Fira 1970). Remarks (summarised from literature). Live specimens measure ~ 2 mm. Proboscis hooks are 14 μm long, with a funnel-shaped base. A single testis is present. A pair of seminal vesicles and several prostatic glands enter the proximal end of the elongate copulatory bulb. The bulb contains an elongate prostatic vesicle which empties into a long, weakly sclerotised ejaculatory duct. The most distal part of the ejaculatory duct is densely armed with very small spines. The vitellarium and ovary are unpaired. Ax (1959) provides no further information on the organisation of the female genital system in C. euxeinos and no type material was available for us to examine. According to Noldt & Hoxhold (1984), it is impossible to distinguish C. euxeinos from C. pacifica, C. terminalis and C. asica with certainty. However, it is clear that the cirrus in C. asica and C. terminalis is unarmed. Based on this difference, these two species can be distinguished from C. euxeinos with relative ease. The distal end of the cirrus is armed in C. euxeinos and C. pacifica and these two species could conceivably be synonymous. However, based on the drawings of Ax (1959) and Noldt & Hoxhold (1984), we consider this unlikely., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 471, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Ax, P. (1959) Zur Systematik, Okologie und Tiergeographie der Turbellarienfauna in den ponto-kaspischen Brackwassermeeren. Zoologische Jahrbucher Abteilung fur Systematik, Geographie und Biologie der Tiere, 87, 43 - 184.","Mack-Fira, V. (1970) The turbellarian fauna of the Romanian littoral waters of the Black Sea and its annexes. In: Riser, N. W. & Morse, M. P. (Eds.), Biology of Turbellaria. Libbie H. Hyman Memorial Volume. McGraw-Hill Company, New York, New York, pp. 248 - 290.","Noldt, U. & Hoxhold, S. (1984) Interstitielle Fauna von Galapagos. XXXIV. Schizorhynchia (Plathelminthes, Kalyptorhynchia). Microfauna Marina, 1, 199 - 256."]}

Cheliplana tridigitata (Armonies, 2018) Diez, Reygel & Artois, 2019 Synonyms. Dactyloplana tridigitata Armonies, 2018 Material examined. None. Known distribution. Sylt, Germany (Armonies 2018). Remarks (summarised from literature). Live specimens are reddish in colour and measure between 0.9 and 1 mm. The caudal body end is provided with an annulated tail. The proboscis has a total length of ~42 μm, with proboscis hooks measuring 22–23 μm and tongues measuring ~20 μm. The hooks consist of a straight proximal part, ~12 μm long and bearing a small denticle, followed by a branched, distal part, consisting of three finger-like spines (10–11 μm long). Proboscis sidepieces were not reported. The copulatory apparatus consists of an ovoid copulatory bulb into which a pair of seminal vesicles enter proximally. The bulb contains a 27-µm-long cirrus armed with fine spines. The cirrus is cylindrical proximally and distally ends in a spherical region., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 484, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Armonies, W. (2018) Uncharted biodiversity in the marine benthos: the void of the smallish with description of ten new Platyhelminth taxa from the well-studied North Sea. Helgoland Marine Research, 72, 18. https: // doi. org / 10.1186 / s 10152 - 018 - 0520 - 8","Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1"]}

Cheliplana barringtonensis Noldt & Hoxhold, 1984 Material examined. Reference material. 9 serially sectioned specimens from the Galápagos, including the holotype (P1841–P1849). Known distribution. Galápagos archipelago, Ecuador (Noldt & Hoxhold 1984). Remarks. Our observations and measurements correspond to the species description by Noldt & Hoxhold (1984). Specimens are up to 1.3 mm long. The proboscis has an overall length of 40–50 μm and is armed with 17–25- µm-long, curved hooks. Proboscis hooks have a 4–5-μm-wide, funnel-shaped base. Hook supports are 25 to 30 μm long. The soft proboscis sidepieces have an overall length of 24–29 μm and bear a 9-µm-long, sclerotised bristle. The epithelium lining the oral cavity is armed with 10-µm-long, sclerotised spines. A single testis is located alongside the pharynx. The prostatic glands with eosinophilic secretion and paired seminal vesicles surrounded by longitudinal muscles proximally enter the male copulatory bulb. The ejaculatory duct widens distally to form a sclerotised cirrus. The cirrus measures 20 to 25 μm and is armed with 2–3-µm-long spines. The distal part of the cirrus lacks spines and is partially everted to form a sclerotised papilla protruding into the common genital atrium. A short vagina externa opens posterior to the common genital pore and leads to a large, sac-like bursa. A tubular spermatic duct connects the bursa to the ovary., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 465, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Noldt, U. & Hoxhold, S. (1984) Interstitielle Fauna von Galapagos. XXXIV. Schizorhynchia (Plathelminthes, Kalyptorhynchia). Microfauna Marina, 1, 199 - 256."]}

Cheliplana paradoxa Noldt, 1989 Synonyms. Dactyloplana paradoxa (Noldt, 1989) Armonies, 2018 Material examined. None. Known distribution. Sylt, Germany (Noldt 1989). Remarks (summarised from literature). Noldt (1989) describes C. paradoxa as a comparatively small species of Cheliplana, with a total body length of 370–580 μm in fixed specimens. The prepharyngeal cavity is relatively short and unarmed. The pharynx is cylindrical and situated in the anterior body half. The proboscis hooks are 21–25 μm long. The 11–15-µm-long proximal part of each hook is straight and tubiform, and distally splits into a pair of slightly curved, 10–11-µm-long hooks. Noldt (1989) did not observe proboscis sidepieces. A single testis is located alongside the pharynx. Seminal vesicles are paired and enter the copulatory bulb proximally. Strongly developed longitudinal muscles surround the copulatory bulb. The distal part of the copulatory bulb is filled with parenchymatic tissue, while the proximal part is taken up by a prostatic vesicle. The ejaculatory duct distally forms a sclerotised cirrus, which is divided into three distinct regions: a proximal, ~13–15-µm-long, unarmed section; a middle section with a diameter of 4–5 μm, armed with very small spines; and a distal section with a diameter of 11–13 μm, asymmetrically provided with 4-µm-long spines. A single genital opening was observed. Noldt (1989) did not observe any female genital organs., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 476, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Noldt, U. (1989) Kalyptorhynchia (Plathelminthes) from sublittoral coastal areas near the island of Sylt (North Sea) I. Schizorhynchia. Microfauna Marina, 5, 7 - 85.","Armonies, W. (2018) Uncharted biodiversity in the marine benthos: the void of the smallish with description of ten new Platyhelminth taxa from the well-studied North Sea. Helgoland Marine Research, 72, 18. https: // doi. org / 10.1186 / s 10152 - 018 - 0520 - 8"]}

Cheliplana pusilla Brunet, 1968 Material examined. 1 serially sectioned specimen from France (the holotype) (SMNH Type 2820). Known distribution. Golfe de Marseille, France (Brunet 1968). Remarks Our observations correspond to those of Brunet (1968). Specimens are small and unpigmented, with a total body length of 0.5–0.6 mm. The proboscis hooks are 12–14 μm long.A single testis is present near the pharynx. The copulatory bulb is situated in the posterior third of the body and is ~50 μm long. A pair of seminal vesicles proximally enters the copulatory bulb. The copulatory bulb is entirely surrounded by longitudinal muscles. Circular muscles surrounding the distal half of the copulatory bulb were observed. The distal part of the ejaculatory duct forms a cirrus armed with fine spines. Proximally, the cirrus is a slightly curved tube with very fine spines. Distally, the tube is asymmetrical and provided with large spines. This distal part measures 10–12 μm. A single, large ovary lies in the posterior part of the body, partly alongside the male copulatory apparatus. A globular bursa is situated near the caudal body end and, according to Brunet (1968), connects to the ovary via a very small, sclerotised spermatic duct. Upon examination of the serially sectioned holotype, we did not observe this connection. A vagina externa was not observed., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 477-478, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana stylifera Karling, 1949 Material examined. 6 whole-mounted specimens (SMNH Lectotype 2792, SMNH 82333–82337) and 1 serially sectioned specimen (SMNH 82338) from Germany. Known distribution. Ahus, Sweden (Karling 1949). Hanko and Balget, Finland (Karling 1949). Eiderstedt Peninsula, Germany (Karling 1963). Amrum, Germany (Schilke 1970). Sylt, Germany (Noldt 1989). Römö, Denmark (Schilke 1970). Remarks. Specimens are yellow-brown in colour. Karling (1949) reports a total body length of less than 1 mm, with measurements ranging from 0.75 to 0.90 mm. A single adhesive belt is present caudally. The genital opening and atrial organs are situated in the caudal third of the body. Numerous vacuoles were observed in the epithelium. The proboscis hooks are 17–18 μm long. The copulatory bulb is ~120 μm long [120 μm according to Ax (2008); 123 μm according to Karling (1949)]. The 43–45-µm-long stylet is surrounded by a cirrus armed with very small spines., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 482, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Karling, T. G. (1949) Studien uber Kalyptorhynchien (Turbellaria) 2. Die Familien Karkinorhynchidae und Diascorhynchidae. Acta Zoologica Fennica, 58, 1 - 42.","Karling, T. G. (1963) Die Turbellarien Ostfennoskandiens. V. Neorhabdocoela. 3. Kalyptorhynchia. Fauna Fennica, 17, 5 - 59.","Schilke, K. (1970) Kalyptorhynchia (Turbellaria) aus dem Eulitoral der deutschen Nordseekuste. Helgolander wissenschaftliche Meeresuntersuchungen, 21, 143 - 265. https: // doi. org / 10.1007 / BF 01630522","Noldt, U. (1989) Kalyptorhynchia (Plathelminthes) from sublittoral coastal areas near the island of Sylt (North Sea) I. Schizorhynchia. Microfauna Marina, 5, 7 - 85.","Ax, P. (2008) Plathelminthes aus Brackgewassern der Nordhalbkugel. Abhandlungen der Mathematisch-naturwissenschaftlichen Klasse, Jahrgang 2008, 1. Akademie der Wissenschaften und der Literatur, Mainz, Franz Steiner Verlag, 696 pp."]}

Cheliplana marcusi (Karling, 1956) Karling, 1983 Synonyms Rhinepera marcusi Karling, 1956 Rhinepera divisa Schilke, 1970 Material examined. None. Known distribution. Amrum, Germany (Schilke 1970). Tylösand, Kattegat, Sweden (Karling 1983). Sylt, Germany (Noldt 1989). Remarks (summarised from literature). The species was adequately described by Karling (1956). Live specimens are slightly reddish in colour and are 0.7 mm long. The proboscis has an overall length of 31 μm and is armed with 17–19-µm-long spines (Schilke 1970; Karling 1983). Karling (1961, 1983) describes a pair of denticles on the proboscis hooks. While Schilke (1970) mentions a great degree of similarity in the basal part of the proboscis hooks between his specimens and the specimens described by Karling (1961), no denticles are reported for the specimens from Amrum Island. An oral tube without spines connects the mouth, located directly behind the proboscis, to the pharynx. The common genital opening is situated near the caudal body end. A single testis is situated posterior to the pharynx. The male copulatory apparatus is positioned at 75%. A single seminal vesicle enters the copulatory bulb proximally. The copulatory bulb contains a proximal, bulbous prostatic vesicle, which connects to an armed cirrus distally. There is a relatively large size difference between the cirrus lengths reported by Schilke (1970) (27–29 μm) and Karling (1983) (80 μm). The cirrus consists of several parts, differentiated by the organisation and shape of the spines. Proximally, the cirrus is tubular and lined with very fine spines or sclerotised warts (Schilke 1970). This part is followed distally by a ring of somewhat larger spines, described by Karling (1983) as ‘small teeth on 3.3 μm broad plates’. More distally, the cirrus is tubular and somewhat widened compared to the proximal part, but armed with similarly fine spines. The distal sclerotised rim folds over to form a penis papilla, projecting into the male atrium. A single ovary is situated alongside the male copulatory apparatus. A vitellarium extends between the ovary and testis. Based on the construction of the copulatory apparatus, Karling (1983) considered R. divisa and C. marcusi to be synonymous. However, there are some interesting differences in the descriptions of these species, most notably the size difference of the cirrus and the presence of denticles on the proboscis hooks of C. marcusi. Karling (1983) dismisses these differences as being either the result of the specimens’ state of contraction or features not observed by Schilke (1970). Re-examination of Schilke’s type material, which we were unable to obtain at this time, or newly collected material from the type localities, is imperative to ascertain whether these specimens indeed belong to the same species., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 474-475, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Karling, T. G. (1956) Morphologisch-histologische Untersuchungen an den mannlichen Atrialorganen der Kalyptorhynchia (Turbellaria). Arkiv for Zoologi, Serie 2, Band 9 (7), 187 - 279.","Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x","Schilke, K. (1970) Kalyptorhynchia (Turbellaria) aus dem Eulitoral der deutschen Nordseekuste. Helgolander wissenschaftliche Meeresuntersuchungen, 21, 143 - 265. https: // doi. org / 10.1007 / BF 01630522","Noldt, U. (1989) Kalyptorhynchia (Plathelminthes) from sublittoral coastal areas near the island of Sylt (North Sea) I. Schizorhynchia. Microfauna Marina, 5, 7 - 85.","Karling, T. G. (1961) Zur Morphologie, Entstehungsweise und Funktion des Spaltrussels der Turbellaria Schizorhynchia. Arkiv for Zoologi, 13 (11), 253 - 286."]}

Cheliplana vestibularis de Beauchamp, 1927 Material examined. None. Known distribution. Bay of Arcachon, France (de Beauchamp 1927). Étang de Canet, France (Ax 1956). Remarks (summarised from literature). According to de Beauchamp (1927), live specimens are at most 1 mm long. De Beauchamp (1927) describes the specimens’ posterior end as capable to take on a four-lobed aspect; however, we suspect this may be the result of the action of the adhesive belt in combination with compression of the specimen. Small rhabdites are reported from the middle region of the body. Adhesive cells, which appear pearl-like in live specimens, are present over the entire surface of the specimen. The split proboscis bears a pair of 16-μm-long hooks. Soft sidepieces are present, but no bristles on the sidepieces are reported. A pair of partially fused testes is present near the caudal end of the pharynx. A pair of vasa deferentia runs from the testes towards the seminal vesicles, which empty into the proximal part of the copulatory bulb. The copulatory bulb is more or less pear-shaped and has a globular prostatic vesicle in its proximal part. The distal half of the bulb contains an eversible cirrus armed with minute, sclerotised spines. The paired vitellaria run ventro-laterally on either side of the body. A single ovary is situated alongside the common genital atrium. A curved bursa is present near the caudal end of the body., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 486, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["de Beauchamp, P. (1927) Rhabdocoeles des sables a diatomees d'Arcachon I. - Coup d'oeil sur l'association Schizorhynchidae. Bulletin de la Societe Zoologique de France, 52 (5), 351 - 386."]}

Brunet (1968) provided an identification key to the species of Cheliplana. Here, we give an updated identification key that should enable the recognition of different species in the field. Hence, our key relies almost exclusively on characters that can be observed on live specimens using a simple microscope setup and it avoids characters only observable on histologically stained serial sections. 1. Each proboscis hook consisting of a long proximal part and a branched tip........................................ 2 - Each proboscis hook a simple, curved hook................................................................ 4 2. Only one seminal vesicle. Epidermis covered by glands resembling warts................................ C. verrucosa - Two seminal vesicles. Epidermis not as such................................................................ 3 3. Branched part of the proboscis hooks consisting of a pair of solid thorns................................. C. paradoxa - Branched part of the proboscis hooks consisting of three slender spines................................. C. tridigitata 4. Copulatory organ with a stylet. A cirrus, armed or unarmed, may be present....................................... 5 - Copulatory organ with an unarmed or armed cirrus, never with a stylet........................................... 8 5. Copulatory organ with a complex, broad stylet combined with a cirrus. Cirrus with a striated appearance: striation running diagonally in the proximal part of the stylet and longitudinally over the medial and distal parts of the cirrus...... C. boadeni - Copulatory organ not as such............................................................................ 6 6. Stylet a relatively long (~43 μm), simple, slightly curved needle, running centrally through the armed cirrus..... C. stylifera - Stylet very short (~ 10 µm), wide and tube-like. No armed cirrus present.......................................... 7 7. Two seminal vesicles present, one of which of normal build, the other elongate and surrounded by a thick layer of longitudinal muscle. No sclerotised spermatic ducts present.................................................. C. uruguayensis - Only one seminal vesicle present. A sclerotised spermatic duct connects ovary and bursa........................ C. targa 8. Cirrus unarmed....................................................................................... 9 - Cirrus armed with (small) spines........................................................................ 14 9. Cirrus very long (> 100 µm)............................................................................ 10 - Cirrus much shorter (C. vaginalis 11. Cirrus with a distal sclerotised cap or papilla....................................................... C. terminalis - Cirrus without a distal sclerotised cap................................................................ C. asica 12. One of the seminal vesicles atrophied, without any connection to the testis and not containing sperm, the other one functional..................................................................................... C. spuriaseminalis - Both seminal vesicles identical or not, but always functional and containing sperm................................ 13 13. Cirrus with longitudinal ridges, visible as small stripes. Cirrus slightly curved at the proximal end. Vagina externa elongated and not divided into several compartments........................................................ C. rubescens - Cirrus lacking longitudinal ridges. Cirrus curved slightly distally. Vagina externa long, with a strongly developed musculature and proximally subdivided into three compartments................................................ C. hypergyna 14. One or more accessory cirri present apart from the cirrus itself................................................ 15 - No accessory cirri present............................................................................. 17 15. One accessory cirrus, entirely armed with small spines. Three sclerotic spermatic ducts present............. C. deverticula - More than one accessory cirrus......................................................................... 16 16. Two elongate accessory cirri, each armed with small spines on one side only, the other side unarmed............ C. textilis - Three relatively large accessory cirri present. All accessory cirri armed with fine spines covering the entire inner surface................................................................................................. C. curini 17. Ejaculatory duct (including the cirrus) long to very long, with a smooth, sclerotised wall. Spiny part restricted to the distal end, often only to a small distal portion that is widened.......................................................... 18 - Ejaculatory duct shorter and/or armed with spines over its entire length......................................... 23 18. Only a single seminal vesicle present..................................................................... 19 - Two seminal vesicles present........................................................................... 20 19. Seminal vesicle completely caudal, with copulatory bulb oriented forwards.............................. C. gibarenha - Combination of traits not as described above......................................................... C. schilkei 20. Ejaculatory duct relatively long, with a simple bend......................................................... 21 - Ejaculatory duct very long, with many bends or coiled....................................................... 22 21. Spiny part of the cirrus with strong spines, restricted to the most distal tip................................. C. hiemalis - Spiny part of the cirrus longer and in two parts: a longer proximal part covered with small spines and a shorter distal part that is widened and covered by larger spines....................................................... C. subproximalis 22. Occurs around the Galápagos archipelago.......................................................... C. pacifica - Occurs in the Black Sea area.................................................................... C. euxeinos 23. Ejaculatory duct widened in some places and distally forming a wound cirrus. Proximal part of the cirrus showing small spines; distal part armed with spines that increase in size towards the distal end. Distal point of the cirrus surrounded by a sclerotised cap................................................................................................ 24 - Female system without visible cap-shaped structure. Cirrus not as described above................................ 25 24. Obvious, sperm-containing structure occurring alongside the ovary. Short sclerotised cap surrounding the cirrus.................................................................................................... C. curvocirro - Without such an obvious, sperm-containing structure. Long, urn-shaped sclerotised cap surrounding the cirrus.............................................................................................. C. curacaoensis n. sp. 25. Cirrus consisting of three distinct regions: a proximal part with very fine spines, a median region consisting of a ring of large hooks set in sclerotised ‘pockets’ and a relatively wide distal part with fine spines of up to 8 µm long.................. 26 - Cirrus not as described above........................................................................... 28 26. Proximal cirrus region very short (~ 20 µm) and shorter than the distal part....................................... 27 - Cirrus with a long proximal part, ~ 55 µm long. A pair of seminal vesicles present............................ C. setosa 27. Only a single seminal vesicle present.............................................................. C. evdonini - Two seminal vesicles present............................................................ C. hawaiiensis n. sp. 28. Only a single seminal vesicle present..................................................................... 29 - Two seminal vesicles present........................................................................... 31 29. Cirrus very short, ‘cup-shaped’. A thinly sclerotised penis papilla is present............................ C. mauii n. sp. - Cirrus not as described above........................................................................... 30 30. Cirrus consisting of three regions: a tubular part, armed with fine hooks; a distal part with larger spines; between these a girdle of spines set onto sclerotised plates with a cross-section of ~ 3 µm....................................... C. marcusi - Cirrus not with three clearly defined zones, slightly curved. The entire cirrus armed with slender, densely packed spines................................................................................................ C. remanei 31. Cirrus conspicuously wide and short, at most three times as long as it is wide..................................... 32 - Cirrus not conspicuously wide and/or short. Cirrus at least three times as long as wide.............................. 36 32. Cirrus asymmetrically armed, with a crescent-shaped curve distally...................................... C. pusilla - Cirrus not as described above........................................................................... 33 33. Cirrus pear-shaped, with its widest part proximally.................................................. C. piriformis - Cirrus not pear-shaped................................................................................ 34 34. Armed part of the cirrus with 5–7-µm-long spines distally. Distally, the cirrus transitions into an unarmed channel of roughly the same length as the cirrus, ending in a small, non-sclerotised penis papilla..................................... 35 - Cirrus not as described above, but rather barrel-shaped, with spines of 1.5–2 µm long. Ejaculatory duct slightly widened, directly proximal to the cirrus. Walls of this expansion possibly to some degree sclerotised................ C. microcirrus 35. Entire copulatory bulb measuring ~ 250 µm, with an internal seminal vesicle, consisting of a single part. Cirrus with spines of uniform length, organised in a large number of longitudinal rows..................................... C. gemmifera - Entire copulatory bulb ~ 80 µm long. Internal seminal vesicle present and consisting of two separate lobes. Hard ring-like structures are present in the ejaculatory duct. Cirrus spines organised in 7–8 longitudinal rows. Spines 10–14 µm long proximally and 5–7 µm distally.......................................................................... C. mamkaevi 36. Male atrium with a blindly ending diverticulum. Prostatic vesicle emptying virtually directly into the cirrus. Cirrus measuring 45–50 μm, with the distal end surrounded by a sclerotised papilla........................................ C. pileola - Male atrium without diverticle. Cirrus not as described above................................................. 37 37. Cirrus consisting of a rigid, tubular proximal part and a shorter distal, crescent-shaped region, armed with both fine and larger, lamellar spines....................................................................... C. asinaraensis n. sp. - Cirrus not as described above........................................................................... 38 38. Cirrus rod-shaped, ~30-µm-long and uniform in width. Proboscis with a sclerotised base proximal to the hook supports................................................................................................. C. firmata - Cirrus not as described above........................................................................... 39 39. Proximally to the armed cirrus, the ejaculatory duct is sclerotised to form a fine, sclerotised tube. Cirrus 20–25 µm long, with spines measuring 2–3 µm. Distal cirrus end consisting of a sclerotised tube of ~ 12 µm, surrounded by a cap or papilla........................................................................................... C. barringtonensis - Cirrus and ejaculatory duct not as described above.......................................................... 40 40. Cirrus curved or sinusoidal............................................................................. 41 - Cirrus straight, without curves.......................................................................... 45 41. Vagina not obvious on live specimens. Tail never elongated................................................... 42 - Posterior third of the body sometimes elongated into a long tail. Vagina clearly visible on live specimens. Bursa connected to the ovary via three sclerotised spermatic ducts............................................................. 44 42. Cirrus with a highly distinct curve or loop................................................................. 43 - Cirrus sinusoidal........................................................................... C. vestibularis 43. Cirrus slender and very long, showing a distinct loop. Copulatory bulb showing transverse ridges or stripes................................................................................................... C. longissima n. sp. - Cirrus with a characteristic U-bend in the distal half. Distalmost part of the cirrus somewhat widened...... C. cubana n. sp. 44. Two functional seminal vesicles................................................................. C. varicauda - One functional seminal vesicle, sometimes a second, smaller, blindly ending seminal vesicle present.......... C. sarnensis 45. Cirrus ~ 55 µm long and completely armed. Spines’ size decreasing towards the distal end. A pair of incompletely fused testes present alongside the pharynx................................................................. C. orthocirra - Cirrus 45–75 µm long, not as described above............................................................. 46 46. Cirrus with spines of varying thickness and length: proximal spines very short, medial spines long, distal spines short again. Extreme distal end of the cirrus thinly sclerotised and folded over to form a short penis papilla.............. C. canariensis - Cirrus not as described above, cirrus spines all equal in size................................................... 47 47. Testes clearly paired, on opposite sides of the pharynx and with a connection anterior to the pharynx. Cirrus ~ 45 µm long and asymmetrically armed: spines increasing in length toward the distal end on one side, spines decreasing in length toward the distal end on the other side.................................................................... C. californica - Only one testis present. Cirrus not as described above........................................................ 48 48. Cirrus ~ 75 µm long. Distal part of the cirrus unarmed and evertable to form a small penis papilla............ C. elkhornica - Cirrus ~ 25 µm long........................................................................ C. santiaguera, Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 490-492, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana pileola Jouk & De Vocht, 1989 Material examined. Reference material. The holotype (whole-mounted) specimen (SMNH Type 6981) and the 3 paratypes (two whole mounts and 1 serially sectioned specimen HU 145–147) from Kenya. 1 whole mount from South Africa (HU VII.4.07). Known distribution. Tudor Creek, Mombasa, Kenya (Jouk and De Vocht 1989). Sodwana Bay, Kwazulu-Natal, South Africa (Willems et al. 2017). Remarks. According to the description of Jouk and De Vocht (1989), specimens reach a total body length of 0.7–0.9 mm. Caudally, a single, continuous girdle of haptic glands is present. The pharynx is situated in the anterior third of the body. The prepharyngeal cavity is not armed with spines, though Jouk and De Vocht (1989) report cellular bodies with nuclei protruding above the epithelial surface of the prepharyngeal cavity. The proboscis is armed with a pair of smooth hooks (14–18 μm long) and has a pair of soft proboscis sidepieces, without sclerotised rods. The hook supports are 7–13 μm long. A pair of partially fused testes is present alongside and posterior to the pharynx. The male copulatory organ is present in the posterior 1/4. A pair of seminal vesicles enters the proximal end of the copulatory bulb, which contains a 25–30-µm-long prostatic vesicle, with a single type of secretion. The cirrus is 45–50 μm long and armed with sclerotised spines that somewhat increase in size towards the distal end. The distal end of the cirrus is surrounded by a sclerotic penis papilla of ~20 μm long. The copulatory bulb, as well as two glandular systems and a blind diverticulum empty into a male atrium. The single ovary is located alongside the male copulatory system. A large bursa lies alongside the ovary. The presence of a vagina externa could not be ascertained.

Cheliplana firmata Brunet, 1968 Material examined. Reference material. 2 whole mounts, including the neotype (SMNH Neotype 2817, SMNH 82469). Known distribution. Île Calseraigne, Provence-Alpes-Côte d’Azur, France (Brunet 1968). Remarks. Our observations correspond to those of Brunet (1968). The total body length comprises 0.8 to 1 mm. The proboscis is armed with a pair of 14–16-µm-long proboscis hooks and bears a pair of soft sidepieces, each carrying three small bristles. At the base of the muscular hook supports, a small, sclerotised piece forms the attachment point for the two muscular bulbs. A single, bilobed testis is positioned ventrally alongside the pharynx. Seminal vesicles are paired. The copulatory bulb measures ~55 μm in cross-section and contains a small, spherical prostatic vesicle. The tubular cirrus is 29 μm long, thinly sclerotised and armed with very fine spines. The bursa lies adjacent to the ovary., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 472, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana mamkaevi Evdonin, 1977 Material examined. None. Known distribution. Putyatin Island, Peter the Great Gulf, Russia (Evdonin 1977). Kunashir Island, Pacific Coast, Russia (Evdonin 1977). Kronocka Bay, Kamchatka Peninsula, Russia (Evdonin 1977). Anadyrsk and Olindorstvik, Bering Strait, Russia (Evdonin 1977). Remarks (summarised from literature). Specimens are up to 2.5 mm long. The proboscis is armed with a pair of sclerotised 10–28-µm-long hooks. The proboscis sidepieces are not sclerotised and of the same length as the hook supports. The post-rostral bulb measures approximately twice the length of the hook supports. The pharynx bears eight tubercles or papillae on its anterior rim. The prepharyngeal tube is armed with numerous small spines. The common genital opening lies at 75%. An unpaired testis is situated dorsal to the prepharyngeal cavity. A pair of seminal vesicles enters the proximal end of the oviform, 100-µm-long copulatory bulb to form an internal seminal vesicle. This internal seminal vesicle bears two blind-ending pockets, which envelop a small prostatic vesicle, containing coarse-grained secretion in the middle part and fine-grained secretion peripherally. Distally, the ejaculatory duct forms a sclerotised, 30–60-µm-long cirrus. The spines of the cirrus measure 10–14 μm proximally and 5–7 μm distally. A single ovary is situated caudally to the copulatory apparatus. Evdonin (1977) mentions the presence of a vagina interna, which connects to a bursa adjacent to the ovary. The copulatory apparatus resembles that of C. gemmifera in its general organisation. The short, armed cirrus and the internal seminal vesicle in the copulatory bulb as drawn by Evdonin (1977) are nearly identical to those in C. gemmifera. Noldt (1989) discusses these similarities, but raises a number of differences distinguishing the species, including the different sizes and structures of the copulatory bulb and the presence of a vagina interna in C. mamkaevi. The new specimens of C. gemmifera (see earlier) did not allow study of the female system or detailed observations of the copulatory bulb’s fine structure. Without additional study of the type material or newly collected material, we refrain from synonymizing the two species. Certainly, the similarities between the two species, in particular the properties of the lobed internal seminal vesicle and prostatic glands, are striking and the two species, if indeed distinct, are likely closely related., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 474, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Evdonin, L. A. (1977) Monograph of the Turbellaria Kalyptorhynchia in the fauna of the USSR and adjacent areas. Fauna USSR, Turbellaria, 1 (Pt. 1.), New Series, 115, 1 - 400.","Noldt, U. (1989) Kalyptorhynchia (Plathelminthes) from sublittoral coastal areas near the island of Sylt (North Sea) I. Schizorhynchia. Microfauna Marina, 5, 7 - 85."]}

Cheliplana curini Gobert, Reygel & Artois, 2017 Material examined. Reference material. 9 whole-mounted specimens, including the holotype (SMNH Type 8905; VII.4.29– VII.4.36), and 8 serially sectioned specimens (HU VII.4.37– VII.4.44) from Lanzarote and Sardinia. Known distribution. Lanzarote, Canary Islands, Spain (Gobert et al. 2017). Sardinia, Italy (Gobert et al. 2017). Remarks. Live specimens are ~ 0.8–1.3 mm long, with orange to bright red pigmentation. The proboscis is ~40 μm long, with smooth hooks measuring 20–27 μm and hook supports of ~20–30 μm. A pair of soft, rod-shaped proboscis sidepieces, without bristles, is present. The horizontally oriented pharynx measures approximately 1/5 of the total body length and connects to the mouth via a long, unarmed prepharyngeal tube. A single testis is positioned near the caudal end of the pharynx. In the posterior half of the body, an elongate copulatory bulb (350–370 μm) is present. A pair of seminal vesicles enters the proximal end of the copulatory bulb, which contains a globular prostatic vesicle. A long ejaculatory duct runs axially through the copulatory bulb. Distally, it forms a sclerotised, unarmed cirrus (56–74 μm) surrounded by three blind-ending accessory cirri. The latter respectively measure 43–50 μm, 50–80 μm and 60–75 μm. Each accessory cirrus is provided with fine spines. The cirrus and accessory cirri merge into a thinly sclerotised, unarmed ‘sleeve’, which makes up a distal penis papilla. A muscular vagina externa opens caudally to the gonopore. The interior lumen of the vagina is lined with a thickened basal lamina, forming a pseudo-cuticula. The vagina connects to a large bursa that consists of two parts: a non-muscular, syncytial region, containing large vesicles adjacent to the ovary, and a distal, saclike region. No spermatic duct between the ovary and bursa is present.