Carcharodorhynchus

Willems, Wim R., Reygel, Patrick, Steenkiste, Niels Van, Tessens, Bart & Artois, Tom J., 2017, Kalyptorhynchia (Platyhelminthes: Rhabdocoela) from KwaZulu-Natal (South Africa), with the description of six new species, Zootaxa 4242 (3), pp. 441-466 : 461

Carcharodorhynchus spec.

( Fig. 8 D–E)

Locality. iSimangaliso Wetland Park, Sodwana Bay, Jesser Point (lighthouse) (27°32'28.4"S, 32°40'47.9"E), green algae from swirl holes on rocky plateau in mid-eulittoral from a highly-exposed, steep beach, December 10, 2009.

Material. One whole mounted individual (HU, no. VII.4.8).

Description and remarks. This single specimen was initially thought to be juvenile, but upon fixation it clearly showed some hard structures, most probably cirrus spines. Therefore, the description of this specimen is very incomplete and should be regarded as provisional.

The slender animal is 0.6 mm long (measured on the whole mount) and lacks eyes. The position of the rosulate pharynx could not be determined on the fixed material. The symmetrical proboscis is 63 µm long (measured on the whole mount) and carries two identical fields of denticles, one on each proboscis half. These fields are U-shaped, approximately 30 µm long, with one half of the field double the width of the other one, and with larger denticles. These denticles are not in rows, but rather randomly positioned. Unfortunately, very little information on the genital system is available. In the caudal third of the body, a 21-µm-long cirrus-like structure is present. Its detailed structure is hard to discern, but it consists of at least three needle-like spines, some of which have a cup-shaped proximal part.

This species can easily be recognised as belonging to the taxon Carcharodorhynchus Meixner, 1938 , based on the presence of denticles on the schizorhynch proboscis. Of the 17 described species, only five ( C. ambronensis Schilke, 1970 , C. arista Noldt & Hoxhold, 1984 C. flavidus Brunet, 1967 , C. involutus Jouk & De Vocht, 1989 and C. polyorchis L’Hardy, 1963 ) have a symmetrical proboscis, as in the South African specimen. However, they clearly differ in the distribution of the denticles on the proboscis and the detailed structure of the male copulatory organ, none of them having such long, needle-like spines as in Carcharodorhynchus spec. (see L’Hardy 1963; Brunet 1967; Schilke 1970; Noldt & Hoxhold 1984; Jouk & De Vocht 1989; Reygel et al. 2014). In addition to C. involutus from the Kenyan coast ( Jouk & De Vocht 1989), this is the second record of a specimen of Carcharodorhynchus from the African coasts. Although this specimen clearly represents a new species, we refrain from formally describing it as there is only one specimen available. This is, in our opinion, not sufficient in a taxonomically-challenging genus such as Carcharodorhynchus .

Figures

FIGURE 8. Cheliplana pileola Jouk & De Vocht, 1989. A. General organisation (from a live specimen). B. Proboscis hook. C. Distal part of ejaculatory duct with cirrus and enveloping papilla. Carcharodorhynchus spec. D. Proboscis. E. Cirrus.