Copelatus vitraci Legros, 1948

Manuel, Michaël, Deler-Hernández, Albert, Megna, Yoandri S. & Hájek, Jiří, 2018, Copelatus Erichson from the Dominican Republic, with the description of a new species, comments on elytral striation and faunistic notes on Antillean species (Coleoptera: Dytiscidae: Copelatinae), Zootaxa 4399 (3), pp. 371-385 : 380-381

Copelatus vitraci Legros, 1948

( Figs 16–18 )

Material examined. DOMINICAN REPUBLIC. 2♂, 5♀ ( NMPC), San Pedro de Macorís, Juan Dolio , 1– 6.xi.2005, 27.xi.2005 and 10–18.xii.2005, R. Fencl leg.

Diagnosis. Based on the presence of 10 dorsal (but see remarks below) and a submarginal elytral stria, Copelatus vitraci is classified within the C. erichsonii -group. In addition, the species is characterised by the combination of the following characters: body rather broadly oval-oblong, with dorsal surface evenly convex; head rufo-testaceous, pronotum dark brown with sides broadly paler, elytron dark brown with rather broad basal testaceous band, often shortly prolonged posteriad near suture, with testaceous sides and with conspicuous apical testaceous spot; pronotum surface without strioles; male with anterior margin of protibia deeply emarginated and bisinuate towards base; shape of median lobe of aedeagus in lateral view very characteristic, strongly emarginate medially on ventral side ( Fig. 17 ); parameres as depicted in Fig. 18 .

Copelatus vitraci is closely allied to the Cuban endemic C. cordovai Megna & Epler, 2012 , as testified by the strongly similar shape of their median lobes. Having studied material of both species, we can state that they are, nevertheless, clearly distinct. Copelatus cordovai differs from C. vitraci notably by its smaller size, paler dorsal colour, much more strongly impressed dorsal striae (with slightly convex inter-striae spaces), absence of an additional stria in female (see below), and slightly different shape of the ventral outline of median lobe in lateral view.

Remarks. Specimens of C. vitraci from the Dominican Republic differ from those from Guadeloupe (type locality) by strong reduction/fragmentation of the elytral dorsal stria 2, and to a lesser extent of stria 1. In one specimen, stria 2 is totally missing and striae 4, 6 and 8 are furthermore reduced to a few short superficial scratches, so that at first sight, this specimen seems to have only 6 dorsal striae. In all examined specimens from Guadeloupe, the 10 dorsal striae are present and complete, even if striae 1 and 2 are generally very superficial.

In addition, this species presents an interesting case of sexual dimorphism in the number of elytral dorsal striae, that has not been previously reported in the literature (notably, in the description of the species by Legros 1948). Females of that species have 11 (sometimes 12) dorsal striae, instead of 10 in males. In females with 11 striae, the additional stria is intercalated between the striae that are counted 9 and 10 in males (and more generally, in erichsonii - group species). In other words, the stria 11 in females corresponds to the stria 10 in males and the stria 10 in females has no equivalent in males. This additional stria is short and superficial, and restricted to the anterior part of the elytron, but nevertheless distinct in all females we have seen from Dominican Republic and from Guadeloupe. In addition, some females (from both localities) have an even shorter and more superficial stria 12 more laterally.

Collection circumstances. Copelatus vitraci was collected at light in coastal wetland (R. Fencl, pers. comm. 2006).

Distribution. Guadeloupe and Dominican Republic (new record).

Figures

FIGURES 14–18. Details of Copelatus. 14. C. caelatipennis habitus (4.4 mm); 15. C. posticatus habitus (6.6 mm); 16. C. vitraci habitus (5.0 mm); 17. median lobe in lateral view of C. vitraci; 18. paramere of C. vitraci. Scale bar (Figs 17–18) = 0.5 mm.