Hydrodessus concolorans, Miller, Kelly B., 2016

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 : 67-70

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus concolorans sp. n. Figs 13, 36, 42

Type locality.

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

Diagnosis.

This species is dorsally shiny and concolorous dark red (Fig. 13A). The lateral elytral carina extends about 1/3 length of elytron (Fig. 13B), the prosternal process is very broad and excavated with the lateral margins rounded (Fig. 13C). The metaventrite carinae are not closely approximated anteriorly (Fig. 13C). Specimens are similar to Hydrodessus continuus , but the metacoxal lines in Hydrodessus concolorans meet the metaventrite/metacoxal suture at a prominent angle (Fig. 13C). The pronotum width is relatively narrowed compared with the greatest width across the elytra (Fig. 13A, EW/PW> 1.3). The male median lobe in lateral aspect is triangular basally, but very slender and evenly curved through apical portion (Fig. 13D). The apex is slender and pointed (Fig. 13D). The median lobe in ventral aspect is relatively parallel-sided to narrowed and narrowly rounded apex (Fig. 13E). The lateral lobe is basally moderately broad with apical half elongate triangular and the apex narrowly rounded (Fig. 13F).

Description.

Measurements. TL = 2.6-3.1 mm, GW = 1.3-1.5 mm, PW = 1.0-1.2 mm, HW = 0.8-0.9 mm, EW = 0.5 mm, TL/GW = 2.0-2.1, HW/EW = 1.6. Body elongate, apically pointed, lateral outline distinctly discontinous between pronotum and elytron (Fig. 13A).

Coloration (Fig. 13A). Head and pronotum red. Elytron red, apically red to red-yellow; some specimens with pale subapical macula. Antennae and palps yellow-red. Legs yellow to yellow-red. Ventral surfaces yellow-red to yellow-brown, lighter on elytral epipleuron and abdominal apex.

Sculpture and structure. Head broad, anterior clypeal margin subtruncate; surface shiny and microreticulate with few scattered, fine punctures; eyes large. Pronotum slightly cordate, widest near middle (Fig. 13A); lateral bead fine; surface shiny with scattered punctures. Elytra elongate, apically pointed (Fig. 13A); lateral carina distinct, extending about 1/3 length of elytron (Fig. 13B); surface indistinctly microretriculate, with fine punctation on surface and two indistinct longitudinal impressed lines (Fig. 13C). Prosternum medially distinctly carinate and setose; prosternal proces large and quadrate, broad, lateral carinae subparallel, medially deeply excavated, apex broadly truncate (Fig. 13C). Metaventrite with anterior process broad, anteriorly truncate, slightly constricted anteapically, distinctly excavated medially; metasternal carinae very well developed, evenly diverging posteriorly, broadly expanded posteriorly, terminating near anterior ends of metacoxal lines (Fig. 13C); other surfaces finely punctate. Legs with most surfaces covered with fine punctation; pro- and mesotarsi moderately broad; metatibia with posteroapical brush of setae; metatrochanter not strongly offset, apex narrowly rounded; metacoxa covered with fine punctures; metacoxal lines conspicuous, broadly separated, divergent anteriorly (Fig. 13C). Abdomen covered with fine punctation; apex of abdominal ventrite VI pointed with small, medial, spinous lobe.

Male genitalia. Median lobe bilaterally symmetrical, in lateral aspect evenly and moderately broadly curved throughout, basal portion small, apical portion long and slender to pointed apex (Fig. 13D); in ventral aspect narrow, lateral margins subparallel, apically evenly convergent to narrowly rounded apex (Fig. 13E). Lateral lobe elongate triangular, basally moderately broad, apically with lateral margins evenly convergent to pointed apex (Fig. 13F).

Female genitalia. Gonocoxosternite broadly triangular, medial margin slightly convex, apicolateral margin slightly concave, apex broadly rounded, anterior portion broad, anteriorly very broadly rounded (Fig. 36). Gonocoxa with apical portion elongate triangular, medial margin medially angled, apex broadly rounded, anterior apodeme elongate, as long as apical portion (Fig. 36). Bursa short, broad; spermathecal duct very long and slender, expanded near receptacle which is semispherical; spermatheca bulbous, with distinctive spermathecal spine; fertilization duct very long and slender (Fig. 36).

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

Variation. Some specimens have pale subapical maculae on the elytra, especially teneral specimens, but most specimens do not have these maculae distinctly visible.

Etymology.

This species is named concolorans, Latin for “concolorous,” for the generally even coloration of specimens.

Distribution.

This species is known only from the type locality area, Cerro de la Neblina, Amazonas, Venezuela (Fig. 42).

Habitat.

Specimens have been collected from along the margins and from rocks in rapids in a forest river and from a muddy oxbow pond in a rainforest clearing.

Specimens.

The holotype male in MIZA is labeled, "VENEZUELA:T.F.Amaz. Cerro de la Neblina Basecamp. 140 m. 0°50'N, 66°10'W 27 January 1985/ Netted along margins of Rio Baria P.J. & P.M.Spangler, R.Faitoute,W.Steiner/ HOLOTYPE Hydrodessus concolorans Miller, 2016 [red label with black line border]."

Paratypes, 120 total. Venezuela, Amazonas, Cerro de la Neblina, basecamp, 0.833°N, 66.167°W, 27 Jan 1985, netted along margins of Rio Baria, 140m, P.J. Spangler, P.M. Spangler, R. Faitoute, W. Steiner (22, USNM, MSBA, MIZA, KUNHM); same except 21 Feb 1985, muddy oxbow pond, rainforest clearing, 140m, P.J. Spangler, P.M. Spangler, R. Faitoute, W. Steiner (11, USNM, MSBA, MIZA, KUNHM); same except 28 Jan 1985, seined from rocks in rapids of Rio Baria, 140m, P.J. Spangler, P.M. Spangler, R. Faitoute, W. Steiner (88, USNM, MSBA, MIZA, KUNHM).