Cheliplana asinaraensis, Gobert & Diez & Monnens & Reygel & Van Steenkiste & Leander & Artois, 2021

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 : 457

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.

Figures

FIGURE 1. A–B. Cheliplana asinaraensis n. sp. A. Habitus of the live specimen. B. Camera lucida drawing of the scerotised cirrus. C–E. Cheliplana cubana n. sp. C. Habitus of the live specimen. D. Camera lucida drawing of the cirrus with the distal part everted. E. Camera lucida drawing of the cirrus and prostatic vesicle of the holotype specimen. Scale bars: B = 20 μm; D, E = 50 μm.