Schizochilus coninxae, Gobert & Monnens & Eerdekens & Schockaert & Reygel & Artois, 2020

Gobert, Stefan, Monnens, Marlies, Eerdekens, Lise, Schockaert, Ernest, Reygel, Patrick & Artois, Tom, 2020, Schizorhynchia Meixner, 1928 (Platyhelminthes, Rhabdocoela) of the Iberian Peninsula, with a description of four new species from Portugal, European Journal of Taxonomy 595, pp. 1-17 : 3-5

Schizochilus coninxae sp. nov.

urn:lsid:zoobank.org:act:001130A5-1784-4395-8619-0D5AD614007D

Fig. 1 A–C

Etymology

This species is named in honour of Hasselt University researcher and close friend to the first author, Laura Coninx.

Material examined

Holotype

PORTUGAL • 1 whole-mount; Algarve region , lagoon near the CCMAR Ramalhete research station; 19 Sep. 2012; E. Schockaert leg.; high eulittoral zone, medium-fine sand among Spartina von Schreber , little detritus or silt, reduced layer more than 5 cm deep; HU 614.

Other material

PORTUGAL • 3 whole-mounts (two of these of insufficient quality for taxonomic work); same collection data as for holotype; HU X.1.32 • 2 whole-mounts (photographs of live specimens available); Olhos de Água ; 37°05′20″ N, 08°11′17″ W; 15 May 2013; B. Tessens leg.; dry sand and algae mixture collected from eastern side of a rocky outcrop; HU X.1.33–X.1.34 .

Description

Specimens approximately 2 mm long, measured on whole-mounts. Eyes are absent. The anteriorlypositioned proboscis (p, Fig. 1A ) is relatively small (1⁄10–1 / 8 of the total body length).A pharynx rosulatus (ph, Fig. 1A ) is present in the caudal body half. A single, seemingly continuous haptic girdle is present at the caudal body end.

The common genital opening is situated in the posterior, at about 80%. A single row of four globular testes (t, Fig. 1A ) is present anterior to the pharynx. A pair of seminal vesicles (vs, Fig. 1A ) enter the proximal end of an elongate copulatory bulb separately. A large prostatic vesicle (vg, Fig. 1A ) occupies the proximal half of the copulatory bulb. The walls of the copulatory bulb are muscular, with several marked constrictions present along the length of the bulb. The distal part contains the stylet (st, Fig 1 A– C). The stylet consists of a straight, tubular proximal part, 17–22 μm long (x = 20 μm, n = 4) and with a diameter of 5 μm, and an irregular, folded ‘plate’- or ‘sheet’-like distal part. The sheet-like distal part is a rather flexible extension that can be positioned anywhere from perpendicular to the tubular part of the stylet, to lying in its extension. In some live specimens, this part was twisted into a corkscrewlike shape. The entire stylet measures 58–63 μm (x = 60 μm, n = 4) and lies within a thin-walled, unarmed cirrus. The distal part of the copulatory bulb forms a sclerotised penis papilla, which measures approximately 20 μm.

Remarks

The unarmed, elongate, split proboscis unambiguously places the new species in the family Schizorhynchidae . The combination of testes organisation in a single row, a pharynx occurring in the second body half and the sclerotised part of the copulatory organ consisting of (at least) a cirrus indicates that the specimens we retrieved belong to the genus Schizochilus Boaden, 1963 .

A tubular stylet is present within the cirrus, similar to the organisation of the copulatory organ in S. bruneti Noldt & Hoxhold, 1984 , S. caecus l’Hardy, 1963 , S. choriurus Boaden, 1963 , S. hoxholdi Karling, 1989 , S. tubulatus Brunet, 1970 , S. parvulus Brunet, 1970 , S. santacruzensis Noldt & Hoxhold, 1984 and S. lanzarotensis Gobert, Reygel & Artois, 2017 . Whereas in most of these species the cirrus is at least partly covered with spines, this is not the case in our specimens, nor in S. tubulatus or S. bruneti . Our specimens differ from the latter two species in the sclerotisation of the cirrus: in S. tubulatus and S. bruneti , the cirrus is thick and characterised by longitudinal grooves, while it is only lightly sclerotised in our specimens. Moreover, the distal sheet-like part we observed is unique for Schizochilus and justifies the establishment of a new species: S. coninxae sp. nov.

Figures

Fig. 1. Schizochilusconinxae sp. nov. A. Habitus of live specimen collectedat the typelocality. B–C. Distal end of the copulatory bulb, with stylet and penis papilla. B. Holotype (HU 614). C. A specimen from the reference collection of Hasselt University (HU X.1.32). Scale bars: 20 µm.