Aponema Jensen 1978

Kovalyev, Shota V. & Miljutina, Maria A., 2009, A review of the genus Aponema Jensen, 1978 (Nematoda: Microlaimidae) with description of three new species, Zootaxa 2077, pp. 56-68 : 58

Aponema Jensen 1978

Emended diagnosis. Microlaimidae . Males monorchic with single outstretched anterior testis. Females didelphic-amphidelphic with outstretched ovaries. Amphidial fovea monospiral, outline rounded. Somatic setae inserted directly on body cuticle, never on a process. Cuticle with transverse striae or optically smooth, without thorns. Pharyngeal bulb varying in shape: from spherical to pyriform. Gubernaculum with or without apophyses. Tail conical or elongated.

Type species. A. torosum ( Lorenzen, 1973) Jensen, 1978

Remarks. The tendency to reduction of the posterior testis occurs among three other Microlaimidae genera. Among Microlaimus species the posterior testis in M. globiceps De Man, 1880 (see Turpeenniemi, 1997) and M. copulatus Jensen, 1988 is only half the size of the anterior testis. In the only species of genus Acanthomicrolaimus Stewart & Nicholas, 1987 —A. jenseni Stewart & Nicholas, 1987 —the posterior testis is also much shorter than the anterior one, and gubernacular apophyses are present as in several Aponema species ( Stewart & Nicholas, 1987). This genus differs from Aponema not only by the presence of a short posterior testis but also in the structure of the cuticle, which bears numerous thorns. Bathynox Bussau & Vopel, 1999 , like Aponema possesses only one anterior testis, but its amphids are located very far from the anterior tip of head and somatic setae are situated on short processes, unlike Aponema .

In Microlaimus nanus Blome, 1982 , the posterior testis is absent, and this allows us to relate this species to Aponema Jensen, 1978 and to regard it as Aponema nanum ( Blome, 1982) comb.n.

Nevertheless, Muthumbi & Vincx (1999) described two Aponema having well-developed anterior and posterior testes— A. decramerae Muthumbi & Vincx 1999 and A. mnazi Muthumbi & Vincx 1999 —without emending the diagnosis of the genus Aponema . We suppose that the main difference of Aponema from other Microlaimids is the lack of a posterior testis so it seems doubtful that A. decraemerae and A. mnazi should be considered as belonging to the genus Aponema and we propose to transfer these species to Microlaimus .