Hydrodessus continuus sp.n.

Miller, Kelly B., 2016, Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini), ZooKeys 580, pp. 45-124 : 70-71

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus continuus sp.n. Figs 14, 44

Type locality.

Venezuela, Amazonas, Cerro de la Neblina, 1km SE basecamp, 0.833°N, 66.167°W.

Diagnosis.

This species differs from others by being dorsally nearly concolorous but with indistinct paler regions subapically and apically (Fig. 14A), having the lateral elytral carina about 1/3 length of elytron (Fig. 14B), having the metaventrite platform (the area between the metaventrite carinae) not strongly constricted (Fig. 14C), and having the metacoxal lines approximately continuously curved with the suture between the metaventrite and metacoxae (Fig. 14C). Specimens are similar to Hydrodessus concolorans and Hydrodessus octospilus in general shape and coloration, but they have the metacoxal lines intersecting the metaventrite/metacoxal suture at an angle. The male median lobe is very broadly curved with an elongate triangular basal portion and the apical portion very slender, evenly curved, and apically sharply pointed (Fig. 14D). The median lobe in ventral aspect is broad with subparallel margins in the basal half (Fig. 14E). In the apical half it is strongly constricted to an elongate, slender apically narrowly rounded apex (Fig. 14E). The lateral lobe is very broad, evenly curved and tapered to the rounded apex (Fig. 14F). There is a dense series of setae in a cluster subapically on the dorsal margin (Fig. 14F).

Description.

Measurements. TL = 2.9-3.0 mm, GW = 1.4 mm, PW = 1.1 mm, HW = 0.8 mm, EW = 0.5 mm, TL/GW = 2.1-2.2, HW/EW = 1.7. Body elongate, apically pointed, lateral outline distinctly discontinous between pronotum and elytron (Fig. 14A).

Coloration (Fig. 14A). Head and pronotum red. Elytra red with large, indistinct pale yellow region subapically, apex diffusely yellow (Fig. 14A). Antennae and palps red-yellow. Legs yellow, metacoxa red. Venter red, lighter red-yellow on head, prothorax, elytral epipleuron and apex of abdomen.

Sculpture and structure. Head moderately broad, anterior clypeal margins broadly rounded; surface shiny, microreticulate with few sparse punctures; eyes large. Pronotum cordate, widest near anterior margin (Fig. 14A); lateral bead fine and distinct throughout length; surface shiny, covered with very fine, indistinct punctures. Elytra elongate, apically pointed (Fig. 14A); lateral carina distinctive but short, about 1/3 length of elytron (Fig. 14B); surface shiny with punctures very fine over entire sur face, with two moderately impressed longitudinal lines on disc. Prosternum medially somewhat swollen, broadly rounded; prosternal process broad, widest at anterior angles, medially strongly excavated, especially apically, apex broadly truncate (Fig. 14C). Metaventrite with anterior process moderately broad, apically truncate, medially distinctly impressed; metasternal carinae distinctive across metasternum, slightly curved and moderately divergent posteriorly, ending near anterior ends of metacoxal lines (Fig. 14C); other surfaces finely punctate. Legs shiny, most surfaces with very fine, indistinct punctures; metatibia with posteroapical brush of setae distinctive; pro- and mesotibiae moderately broad; metatrochanter somewhat offset, apically somewhat rounded; metacoxa covered with fine punctures; metacoxal lines sinuate, anteriorly broadly divergent (Fig. 14C). Abdomen covered with fine punctures; VI apically narrowly rounded.

Male genitalia. Median lobe bilaterally symmetrical, in lateral aspect strongly curved medially, apical portion more linear, basal region large, transverse, apical region slender, apically sharply pointed (Fig. 14D); in ventral aspect broad in basal half, lateral margins slightly concave, medially constricted and apical half strongly convergent to slender, apically pointed apex (Fig. 14E). Lateral lobe very broad basally, broadly curved to narrowly rounded apex, with dense brush of setae subapically along dorsal margin (Fig. 14F).

Female genitalia. Not examined.

Sexual dimorphism. Male pro- and mesotarsi I–III more broadly expanded than female and ventrally with several large adhesive setae.

Variation. Few specimens were examined, and no significant variation was discovered.

Etymology.

This species is named continuus, Latin for “continuous,” for the metacoxal lines which are approximately continuously curved with the suture between the metaventrite and metacoxa.

Distribution.

This species is known only from Cerro de la Neblina, Amazonas, Venezuela.

Habitat.

One specimen was collected from the margin of a river and the other known specimens from a blacklight.

Specimens.

The holotype male is in MIZA labeled, "VENEZUELA,T.F.Amaz. Cerro de la Neblina 1 km SE Basecamp 0°50'N, 66°10'W 140 m., 22 Feb.1985/ Netted along margins of Rio Baria P.J. & P.M.Spangler, R.Faitoute,W.Steiner/ HOLOTYPE Hydrodessus continuus Miller, 2016 [red label with black line border]."

Paratype, 1 total. Venezuela, Amazonas, Cerro de la Neblina, basecamp, 0.833°N, 66.167°W, 6 Feb 1985, blacklight on bank of Rio Baria, 140m, W.E. Steiner (1, USNM).