Cheliplana gemmifera Noldt, 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 : 472

Cheliplana gemmifera Noldt, 1989

Fig. 6G–H

Material examined. New material. GERMANY • observations and photographs of 1 live specimen; Sylt ; 55°01’55”N, 8°29’12”E; 28 Apr. 2015; fine to medium-grained sand with many diatoms, some flocculent organic matter and lumps of clay, taken at a depth of 11.7 m .

Known distribution. Sylt, Germany ( Noldt 1989).

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

Remarks. The newly collected specimen from Sylt was light brown when alive. Noldt (1989) reports body lengths between 1.7 and 1.9 mm. No new measurements of total body length could be taken, as the newly collected specimen was completely contracted. The proboscis has an overall length of 30–35 μm, with the sclerotised hooks reportedly measuring 11–13 μm. The proboscis hooks of the new specimen measure ~13 μm. According to Noldt (1989), proboscis sidepieces are absent. The postrostral bulb is 65–70 μm long, with a diameter of 15 μm according to Noldt (1989), but we were not able to measure these dimensions in our specimen. The prepharyngeal cavity is unarmed. The cylindrical pharynx measures 350–400 μm. A single testis is situated alongside the pharynx. The seminal vesicles are enveloped by longitudinal muscles and separately enter the copulatory bulb. Three types of prostatic glands surround the copulatory bulb and enter the proximal end of the bulb: large glands containing strongly refractive ‘pearl-like’, acidophilic granules (x in Fig. 6H ) (Noldt mentions that these large ‘pearls’ stain both acidophilic and basophilic, but that the latter is probably the result of an artefact); glands with fine, acidophilic secretions; and coarse-grained, basophilic glands. The ‘pearls’ measure 7–11 μm in diameter.

The copulatory bulb is pear-shaped, with a length of 200 to 270 μm (160 μm in the newly collected specimen) and a proximal diameter of up to 85 μm. The proximal 2/3 of the bulb is filled with an internal seminal vesicle. Within the copulatory bulb, the prostatic vesicle contains the fine-grained, acidophilic gland secretions, as well as the ‘pearl-like’ secretions. The ejaculatory duct runs from the distal end of the inner seminal vesicle through the prostatic bulb. A sclerotised cirrus is situated in the distal part of the copulatory bulb ( Fig. 6G ). It is more or less cylindrical and is ~20 μm in long in the new specimen, a bit smaller than the 28–35 μm range reported by Noldt (1989). The interior surface of the cirrus is armed with fine spines. According to Noldt (1989), the spines measure 5–7 μm. The quality of the new specimen did not allow for accurate measurements of the cirrus spines.

A uterus is present, which connects to the common genital atrium. The single ovary is connected to the atrium through a short female duct. A copulatory bursa is positioned adjacent to the ovary. A sclerotised spermatic duct is lacking according to Noldt (1989). Neither vagina interna, nor vagina externa were observed. The vitellarium is unpaired and extends throughout the specimen, from beyond the ovary to the pharynx.

Figures

FIGURE 6. A–C. Cheliplana boadeni Schilke, 1970. A. Camera lucida drawing of the cirrus and stylet. B. Photograph of the copulatory hard structures. C. Photograph of the proboscis. D–F. Cheliplana deverticula Ax, 2008. D. Camera lucida drawing of the cirrus. E. Drawing of the copulatory bulb with cirrus and seminal vesicles. F. Reconstruction of the proximal bursa end and the ovary. Only two of the three seminal ducts are shown. G–H. Cheliplana gemmifera Noldt, 1989 G. Camera lucida drawing of the cirrus. H. Photograph of the copulatory bulb in a live specimen. Scale bars: A–B, D = 50 μm; C, G = 20 μm; E = 100 μm.