A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species Author Gobert, Stefan 0000-0003-1949-9174 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium. & stefan. gobert @ uhasselt. be; https: // orcid. org / 0000 - 0003 - 1949 - 9174 stefan.gobert@uhasselt.be Author Diez, Yander L. 0000-0001-8741-4799 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium. & University of Oriente, Departement of Biology and Geography, Avenida Patricio Lumumba s / n, CP 90500, Santiago de Cuba, Cuba. Beaty Biodiversity Research Centre, Departments of Botany and Zoology, University of British Columbia, 3529 - 6270 University Blvd, Vancouver, BC, V 6 T 1 Z 4 Canada. & yander @ uo. edu. cu; https: // orcid. org / 0000 - 0001 - 8741 - 4799 yander@uo.edu.cu Author Monnens, Marlies 0000-0002-9133-1512 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium. & marlies. monnens @ uhasselt. be; https: // orcid. org / 0000 - 0002 - 9133 - 1512 marlies.monnens@uhasselt.be Author Reygel, Patrick 0000-0001-8721-6290 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium. & patrick. reygel @ uhasselt. be; https: // orcid. org / 0000 - 0001 - 8721 - 6290 patrick.reygel@uhasselt.be Author Van Steenkiste, Niels W. L. 0000-0002-2676-7862 niels. vansteenkiste @ botany. ubc. ca; https: // orcid. org / 0000 - 0002 - 2676 - 7862 niels.vansteenkiste@botany.ubc.ca Author Leander, Brian S. 0000-0003-0798-0470 bleander @ mail. ubc. ca; https: // orcid. org / 0000 - 0003 - 0798 - 0470 bleander@mail.ubc.ca Author Artois, Tom Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium. text Zootaxa 2021 2021-05-17 4970 3 453 494 journal article 6258 10.11646/zootaxa.4970.3.2 281c9017-f55b-47bf-bea0-e511a7173605 1175-5326 4766692 FEABE248-E1EA-48F5-A1AF-0077FE40C257 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 ). FIGURE 2 . A–C . Cheliplana hawaiiensis n. sp. A . Habitus of the live specimen. B . Camera lucida drawing of the proboscis. C . Camera lucida drawing of the sclerotised cirrus. D–E . Cheliplana mauii n. sp. D . Camera lucida drawing of the proboscis. E . Camera lucida drawing of the sclerotised cirrus. F–H . Cheliplana longissima n. sp. F . Camera lucida drawing of the sclerotised cirrus and penile papilla. G . Camera lucida drawing of the proboscis. H . Reconstruction from the left-hand side of the male and female genital organs in the posterior part of the body. Scale bars: B-D, G = 20 μm; E = 10 μm; F = 50 μm. 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.