Cheliplana hawaiiensis Gobert & Diez & Monnens & Reygel & Van Steenkiste & Leander & Artois 2021, n. sp.
Creators: name: Gobert, Stefan
name: Diez, Yander L.
name: Monnens, Marlies
name: Reygel, Patrick
name: Van Steenkiste, Niels W. L.
name: Leander, Brian S.
name: Artois, Tom
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Rhabditophora
Rhabdocoela
Karkinorhynchidae
Cheliplana
Cheliplana hawaiiensis

description: 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.
description: 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