Nematoplana cannoni, Curini-Galletti & Oggiano & Casu, 2002

Curini-Galletti, M., Oggiano, G. & Casu, M., 2002, The genus Nematoplana Meixner, 1938 (Platyhelminthes: Unguiphora) in eastern Australia, Journal of Natural History 36 (9), pp. 1023-1046 : 1033-1034

Nematoplana cannoni sp. nov.

(gures 2, 8D)

Material examined

HOLOTYPE: Australia, Queensland, Coolangatta, Rainbow Beach , lower intertidal in ne sand (July 1993), whole mount (lactophenol) (G21182 2).

Etymology

The species is dedicated to Lester R. G. Cannon (Brisbane Museum), in recognition of his eOEorts to promote knowledge of Australian Platyhelminthes.

Description

The holotype is an adult worm, colourless, about 2 mm long in xed condition. With two pigmented eye-spots, enclosed within the brain capsule. The pharynx, short and collar-shaped, is located in the posterior fth of the body.

Male genital organs. About 60 testes arranged in two irregular rows between vitellaria in front of the pharynx. The copulatory organ consists of two partly fused seminal vesicles, and an elongate muscular bulb (about 90 Mm long), provided with a copulatory stylet. The long seminal vesicles enter the bulb proximally. They are fused caudally for about one-third of their length. The spermiducts enter the seminal vesicles anteriorly. The stylet is a funnel-shaped structure, with a broad, oblique proximal opening and a narrow distal opening. The stylet is 38 Mm long. Its elongate base is about 25 Mm long, with a maximum width of 11 Mm. Ventrally, the stylet is provided with a narrow apophysis (about 15 Mm long). The apophysis is inserted at an angle of about 45ss with the main axis of the stylet. Both in living and xed conditions, it appeared angled in its distalmost part (gure 8D). Numerous, thick longitudinal muscles, most of which are connected basally with the musculature surrounding the bulb, are attached to the apophysis. The distal end of the stylet narrows above the apophysis into a slightly recurved tube, about one-third of the total length of the stylet. It is provided with a short tip (about 12 Mm long), where the narrow distal opening is located. The distal tip is perpendicular to the main axis of the stylet, and ends in a short, slightly curved terminal spike.

Female genital organs. With two oocytes, arranged in a median row in front of the pharynx. Vitellaria stretch from behind the brain to in front of the ovaries; and from behind the pharynx to the level of the copulatory bulb. The oviducts fuse behind the bulb into a short common female duct, which opens to the outside through a female pore, medially between the seminal vesicles.

Discussion

The stylet of the new species, distinctly claw-shaped, with a short distal tip, and a comparatively long, oblique apophysis, is similar to that of the N. coelogynoporoide s species group (which includes N. coelogynoporoide s Meixner, 1938, N. ciliovesiculae Tajika, 1979 and N. riegeri Curini-Galletti and Martens, 1992 ) (cf. Curini-Galletti and Martens, 1992). However, no other Nematoplana has an apophysis which is angled distally. Furthermore, among the N. coelogynoporoide s group, the smallest stylet (that of the Mediterranean N. riegeri , which is about 60 Mm long) is still distinctly larger, with a slender base, and a proportionally longer portion of the stylet above the apophysis than that of N. cannoni . The Indo-Paci c member of the group (the Japanese N. ciliovesiculae ) has a stylet somewhat similar in general shape to that of the new species, but markedly larger (about 130 Mm long), and with a relatively short, obtuse, straight apophysis. Members of the species group are furthermore much larger at maturity (> 10 mm), and have two rows of two to four isolated oocytes in front of the pharynx.

The stylet of N. cannoni is somewhat similar in size and overall shape to that of N. nigrocapitula Ax and Ax, 1974 , from Galapagos Is., which, however, has a shorter apophysis, not angled, a broader and straighter distal part, and a longer, straight terminal spike. Nematoplana nigrocapitula is furthermore distinct for its cephalic pigmentation, and for the presence of cnidosacs, cephalic gut and chorda intestinalis ( Ax and Ax, 1974).