Cheliplana euxeinos Ax, 1959

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 : 471

Cheliplana euxeinos Ax, 1959

Material examined. None.

Known distribution. Sile, Black Sea, Turkey ( Ax 1959). Agigea, Black Sea, Romania ( Mack-Fira 1970).

Remarks (summarised from literature). Live specimens measure ~ 2 mm. Proboscis hooks are 14 μm long, with a funnel-shaped base. A single testis is present. A pair of seminal vesicles and several prostatic glands enter the proximal end of the elongate copulatory bulb. The bulb contains an elongate prostatic vesicle which empties into a long, weakly sclerotised ejaculatory duct. The most distal part of the ejaculatory duct is densely armed with very small spines.

The vitellarium and ovary are unpaired. Ax (1959) provides no further information on the organisation of the female genital system in C. euxeinos and no type material was available for us to examine. According to Noldt & Hoxhold (1984), it is impossible to distinguish C. euxeinos from C. pacifica , C. terminalis and C. asica with certainty. However, it is clear that the cirrus in C. asica and C. terminalis is unarmed. Based on this difference, these two species can be distinguished from C. euxeinos with relative ease. The distal end of the cirrus is armed in C. euxeinos and C. pacifica and these two species could conceivably be synonymous. However, based on the drawings of Ax (1959) and Noldt & Hoxhold (1984), we consider this unlikely.