Carcharodorhynchus multidentatus Brunet, 1979

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 : 12-14

Carcharodorhynchus multidentatus Brunet, 1979

Fig. 3 I–L

Material examined

PORTUGAL • 1 whole-mount (photographs of live specimen available); Algarve region , Faro; 36°57′01″ N, 07°57′35″ W; 23 May 2013; B. Tessens leg.; coarse sand with shell debris from the exposed part of the barrier island opposite Faro at a depth of 26 m; HU X.1.50 .

SPAIN • 1 whole-mount; Andalusia, west of Tarifa ; 36°01′56″ N, 05°37′36″ W; 30 Mar. 2008; B. Tessens and N. Van Steenkiste leg.; fine sand from a long beach; HU X.2.01 .

Previously known distribution

Bay of Marseille, France ( Brunet 1979).

Remarks

Our observations on the specimens collected in Portugal and Spain largely correspond to Brunet’s (1979) original description. Live specimens are transparent and measure 1.2–2.1 mm in length. A large proboscis, consisting of a pair of broad, flattened muscular tongues, is situated at the rostral body end ( Fig. 3 I–J). The proboscis is more or less symmetrical, though the ventral tongue is more rounded than the dorsal tongue. Two fields of numerous, very fine, sclerotised denticles run continuously across the inward-facing surface of both proboscis tongues. The denticles are arranged in 7–10 rows. The size of the denticles is largest on the rows closest to the lateral sides of the proboscis tongues and smallest in the rows facing the middle of the proboscis tongues. A rosulate pharynx is situated in the caudal body half, at approximately 65% of the body length.

According to Brunet (1979), paired rows of two to three testes follicles run laterally in the rostral body half. In the specimen from Portugal, we observed only two large testes directly posterior to the proboscis. A pair of seminal vesicles empty into the proximal end of a short, ovoid-to-spherical copulatory bulb that is between 56 and 72 μm long (x = 64 μm, n = 2). The proximal half to two-thirds of the copulatory bulb contains a prostatic vesicle. The cirrus occupies the distal third of the copulatory bulb, is 15 to 21 µm long and armed with minute spines, arranged in longitudinal rows. These measurements of the copulatory bulb are somewhat larger than what has been reported by Brunet (1979) (cb: 53–57 μm, ci: 13–14 μm). A rather large size variation has also been reported in the copulatory organs of other species in the genus Carcharodorhynchus , such as C. flavidus (see above).

Brunet (1979) did not describe the female system. In one live specimen, we observed a single ovary, situated to one side near the caudal adhesive belt. We were unable to ascertain whether a second ovary was present.

The records mentioned here are the first published records of this species since its original description by Brunet (1979) and are the first records outside of the French Mediterranean. Furthermore, two specimens present in the reference collection of Hasselt University (HU VIII.1.30 and HU VIII.1.47), which were previously identified as C. flavidus ( Gobert et al. 2017) , are now correctly identified as C. multidentatus .

Family Diascorhynchidae Meixner, 1929

Genus Diascorhynchus Meixner, 1928

Figures

Fig. 3. A–D. Carcharodorhynchus tenuis Brunet, 1979 (HU X.1.46). A–B. Proboscis. C–D. Copulatory bulb. E–H. C. flavidus Brunet, 1967. E–F. Proboscis (HU X.1.49). G–H. Copulatory bulb (HU X.1.48– 49). I–L. C. multidentatus Brunet, 1979 (HU X.1.50). I–J. Proboscis. K–L. Copulatory organ. Scale bars: 20 µm.