Cheliplana setosa Evdonin, 1971

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, Zootaxa 4970 (3), pp. 453-494 : 480-482

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.

Figures

FIGURE 9. A–D. Cheliplana setosa Evdonin, 1971 from British Columbia, Canada. A. Live specimen. B. Detail of the male copulatory organs in a live specimen. C. Detail of the proboscis with proboscis hooks and hook supports in a wholemounted specimen. D. Detail of the male copulatory bulb with prostate vesicle and tripartite cirrus in a whole-mounted specimen. E. Cheliplana californica Karling, 1989 from British Columbia, Canada. Detail of the male copulatory bulb with cirrus in the whole-mounted specimen. Scale bars: A = 100 μm; B = 20 μm; C = 10 μm; D–E = 20 μm.