Pseudelzalia, Yu & Xu, 2014

Yu, Tingting & Xu, Kuidong, 2014, Two new nematodes, Pseudelzalia longiseta gen. nov., sp. nov. and Paramonohystera sinica sp. nov. (Monhysterida: Xyalidae), from sediment in the East China Sea, Journal of Natural History 49 (9), pp. 509-526 : 510-511

Genus Pseudelzalia gen. nov.

Diagnosis

Xyalidae with six labial papillae and 10 cephalic setae, cylindrical buccal cavity, elongate (>2 a.b.d.) spicules, and conico-cylindrical tail devoid of terminal setae.

Etymology

Composition of the Greek prefix pseudo- (false) and the generic name Elzalia , referring to the similarity of the genus to Elzalia . Feminine gender.

Type species

Pseudelzalia longiseta gen. nov., sp. nov.

Familial assignment and comparison with related genera and species

The new species Pseudelzalia longiseta sp. nov. described below is obviously a member of the family Xyalidae characterized by transversely striated cuticle, usually 10 cephalic setae, and a single anteriorly outstretched ovary to the left of the intestine. Within the family Xyalidae , Pseudelzalia longiseta sp. nov. is very similar to members of Elzalia Gerlach, 1957 in having the labial papillae, large cylindrical buccal cavity and elongate spicules. However, the new species possesses a character clearly different from all known species of Elzalia , namely, the tail devoid of terminal setae versus with three terminal setae in Elzalia ( Figure 1A, E ). The structure of the tail is a significant character at the genus level within the family Xyalidae , in which the two largest genera, Daptonema Cobb, 1920 and Theristus Bastian, 1865 , are separated only by the tail morphology (conico-cylindrical with terminal setae versus conical without terminal setae) ( Warwick et al. 1998). Pseudelzalia longiseta sp. nov. is also similar to the monotypic genus Parelzalia Tchesunov, 1990 which, however, has a conical buccal cavity with domed anterior end, shorter spicules of about 1 a.b.d. and in particular the presence of terminal setae ( Tchesunov 1990). Accordingly, we propose Pseudelzalia as a new genus. Except for the tail morphology, Pseudelzalia differs from Daptonema and Theristus also by the cylindrical buccal cavity (versus conical) and elongate spicules (>2 a.b.d. versus <2 a.b.d.).

The presence of long caudal setae in the new species Pseudelzalia longiseta is another striking character that is absent in the genera Elzalia , Daptonema and Theristus . However, only one species is described for the new genus and such a character has never been regarded as a generic character within the family Xyalidae . Hence, we consider it a specific character for Pseudelzalia at the current state of knowledge.

Figures

Figure 1. Pseudelzalia longiseta gen. nov., sp. nov. (male holotype, A–D) and Elzalia floresi (E, type species of Elzalia, redrawn from Gerlach 1957). (A, E) Lateral view of tail region. Note the terminal setae are lacking in the genus Pseudelzalia (A), while in Elzalia there are invariably three terminal setae (E). (B) Lateral view of anterior region showing the cylindrical and cuticularized buccal cavity and the papilliform labial sensilla. (C) Lateral view of cloacal region, showing the elongate spicules and adjacent gubernaculum. (D) Overall view, showing the testis. Scale bars: A–C, E, 20 μm; D, 100 μm.