Cheliplana curvocirro Schilke, 1970

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 : 467

Cheliplana curvocirro Schilke, 1970

Material examined. New material. FRANCE • 1 whole mount; Wimereux , near the marine station of the University of Lille ; 50°45’48”N, 1°36’11”E; 15 Sep. 2015; fine sand and shell gravel on rocks; HU X.3.12 • 5 whole mounts; Wimereux , 100 m in front of the marine station of the University of Lille; 50°45’48”N, 1°36’11”E; 16 Sep. 2015; upper 0.2 m of sand with organic matter and algae; HU X.3.13–X.3.17 • 1 whole mount; Wimereux, beach 70 m in front of the cliff south of Wimereux; 16 Sep. 2015; sand and shell gravel between algae; X.3.18 .

Note. No reference material was available to us at the time of this study.

Known distribution. Amrum and Sylt, Germany ( Schilke, 1970; Hellwig 1987; Wehrenberg & Reise 1985). Römö, Denmark ( Wehrenberg & Reise 1985).

Remarks. Our observations largely correspond to those of Schilke (1970). The most important characteristics are listed here.

Live specimens are white-grey in colour and 0.6–1.0 mm (x = 0.8 mm, n = 4) long. A single caudal haptic girdle is present. The muscular proboscis hook supports (18–19 μm) carry a pair of 10–13-µm-long, curved hooks. Proboscis hooks in our specimens are slightly larger (10–16 μm, x = 13 μm, n = 7) than what was reported by Schilke (1970) (10–13 µm). The prepharyngeal lumen is not lined with spines. A single testis is present, either anterior or posterior to the pharynx. Seminal vesicles are ~40 μm long and proximally enter the copulatory bulb. The copulatory bulb measures 96–100 μm (x = 102 μm, n = 7) in our newly collected specimens, falling well within the size range of 90–110 μm reported in literature. Along with the seminal vesicles, a number of prostatic glands enter the bulb. Inside the copulatory bulb, a U-shaped bend at the midpoint of the ejaculatory duct was observed in all newly collected specimens. Distally, the ejaculatory duct forms a long cirrus (70–90 μm). In the proximal part of the cirrus, fine lines and points are visible, which may be very small, fine spines. More distally, the cirrus is armed with conspicuous spines, increasing in size towards the distal end of the cirrus. The sclerotised wall of the distal cirrus end folds over to form a penis papilla. Schilke (1970) reports a papilla of 5–7 μm, similar to the 6–8 μm range measured in the newly obtained specimens (x = 7 μm, n = 3).