Cheliplana elkhornica Karling, 1989

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 : 470-471

Cheliplana elkhornica Karling, 1989

Fig. 7

Material examined. New material. CANADA • 2 whole mounts; British Columbia, Calvert Island, North Beach ; 51°39’53”N, 128°08’47”W; superficial sediment with coarse fraction in run off and intertidal pool near boulders; MI4184–MI4185 .

Reference material 1 whole-mounted specimen from California (holotype, SMNH Type 6800) .

Known distribution. Monterey Bay, California, United States ( Karling 1989).

Remarks. Our observations on the holotype and the new material from Canada mostly correspond to what was reported by Karling (1989). Live specimens are ~ 1.5 mm long ( Fig. 7A ). The haptic girdle (hg, Fig. 7A ) is comprised of ~30 papillae. Proboscis hooks are smooth and are 20–25 μm (California) or 20–23 μm ( Canada) long (h, Fig. 7B ). Proboscis hook supports are ~30 μm long in the Canadian specimens. Blunt side pieces with at least two very short protrusions were observed in one Canadian specimen (sp, Fig. 7B ).

Karling (1989) describes only one testis above the pharynx. However, in one of the Canadian specimens (t, Fig. 7A , right specimen, dorsal view), paired testes could be observed. The other specimen from Canada appears to have only one testis, but it is clearly bilobed (t, Fig. 7A , left specimen, lateral view). A connection between the two lobes or testes may be present, or the orientation of the specimen may play a role in the appearance of the testes. The seminal vesicles are paired. The cylindrical copulatory bulb (cb, Fig. 7C–D ) is ~140 μm (California) or 190–250 μm ( Canada) long and is surrounded by strong longitudinal muscles. The prostatic glands contain a very coarse-grained secretion and enter the copulatory bulb proximally, where they form an elongate prostatic vesicle (pg, Fig. 7C–D ). A short ejaculatory duct is separated from the cirrus by a muscular constriction (arrowhead, Fig. 7D ). The cirrus measures ~75 μm (California) to 80–82 μm ( Canada) and is lined with spines of 4–8 μm (California) up to 10 μm ( Canada) (ci, Fig. 7A,C,D ). The spines are arranged symmetrically, except for the distal part where their orientation appears slightly twisted (Fig. 15B–C in Karling 1989). A short, slightly sclerotised penis papilla (20–27 μm in the Canadian specimens) folds back over the distal part and can be everted (pp, Fig. 7D ).

The female reproductive system was described by Karling (1989) as ‘principally like those in C. californica ’. No vagina externa was observed. Anterior to the genital pore, Karling (1989) reports a small structure, which he interpreted as a temporary vagina. A bursa is situated alongside the ovary (b, ov, Fig. 7A ). In the Canadian specimens, a slightly sclerotised tube was visible between the bursa and ovary (arrow, Fig. 7C ). However, Karling did not observe a spermatic duct. Possibly, this structure is the ‘temporary vagina’ Karling referred to. The holotype and other whole-mounted specimens did not allow for more detailed observations.

Figures

FIGURE 7. Cheliplana elkhornica Karling, 1989 from British Columbia, Canada. A. Lateral (left) and dorsal (right) view of two different live specimens. B. Detail of proboscis with proboscis hooks and hook supports in a live specimen. C. Detail of the atrial organs in a live specimen (arrow: see text proper). D. Detail of the male copulatory organ and cirrus in a live specimen. Scale bars: A = 100 μm; B = 20 μm; C = 50 μm; D = 20 μm.