Hydrodessus maculatus, 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 : 90-91

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus maculatus sp. n. Figs 24, 40, 45

Type locality.

Venezuela, Territorio Federal Amazonas, Cerro de la Neblina, basecamp, 0°50'N 66°10'W.

Diagnosis.

This is a distinctive, elongate, dorsally maculate species (Fig. 24A). The dorsal base color is dark black with red areas medially and laterally on the pronotum and as moderately distinctive, irregular maculae subbasally, subapically and apically on the elytron (Fig. 24A). The lateral elytral carina is distinctive to about 1/2 length of elytron (Fig. 24B). The prosternal process is broad with subparallel lateral margins (Fig. 24C). The metaventrite carinae are prominent, constricted anteriorly and evenly divergent posteriorly (Fig. 24C). The male median lobe in lateral aspect is relatively narrow basally and abruptly curved at base of apical portion (Fig. 24D). The apical portion is relatively straight and medially distinctly expanded along ventral margin with the apex elongate, slender and sharply pointed (Fig. 24D). The median lobe in ventral aspect is slender to a distinct subapical lateral expansion with the apex convergent to a rounded apex (Fig. 24E). The lateral lobe is moderately slender and curved to rounded apex (Fig. 24F). The series of apical setae are on the ventral margin rather than the dorsal as in other species (Fig. 24F).

Description.

Measurements. TL = 3.0-3.1 mm, GW = 1.4 mm, PW = 1.2 mm, HW = 0.8-0.9 mm, EW = 0.5 mm, TL/GW = 2.2, HW/EW = 1.7. Body shape moderately elongate, lateral margin distinctly discontinuous between pronotum and elytron (Fig. 24A).

Coloration (Fig. 24A). Head reddish. Pronotum yellow, reddish medially and along posteromedial margin. Elytra red-brown with three yellow regions (Fig. 24A), one sub-basally with large, irregular macula extending from lateral margin to near suture, one irregular macula at about 2/3 length, and one at apex.

Sculpture and structure. Head broad, anterior clypeal margin subtruncate; surface covered with fine punctures; eyes moderately large (Fig. 24A). Pronotum cordate (Fig. 24A), lateral margins broadly curved in anterior half, slightly convergent posteriorly in posterior half; lateral bead fine anteriorly, posteriorly obscured; surface covered with fine punctures. Elytra elongate, lateral margins subparallel for much of length, apex somewhat pointed (Fig. 24A); lateral carina distinct and conspicuous, extending to near half length of elytron (Fig. 24B); surface of elytron covered with fine punctures. Prosternum medially prominently carinate with fine setae on each side; prosternal process broad, broadest anteriorly, lateral margins slightly convex, strongly impressed medially, apex broadly truncate (Fig. 24C). Metaventrite with metasternal process well developed, conspicuously constricted subapically, surface slightly excavated, carinae well-developed, divergent posteriorly, extending to posterior margin of Metaventrite and ending near anterior ends of metacoxal lines (Fig. 24C); Metaventrite covered with fine punctures. Legs with surfaces covered with fine punctures; metatibia with posteroapical brush of setae; pro and mesotibiae moderately broad; metacoxa very densely covered with fine punctures; metacoxal lines well developed, straight and subparallel, only slightly divergent anteriorly (Fig. 24C). Abdomen densely, finely punctate; stermine VI apically broadly rounded.

Male genitalia. Median lobe bilaterally symmetrical, in lateral aspect moderately curved, with basal portion subtriangular, apical portion curved medially, more straight near apex, subapically somewhat expanded along ventral margin, strongly tapered to elongate, pointed apex (Fig. 24D); in ventral aspect with lateral margins subparallel for most of length, subapically distinctly expanded laterally and apex broadly triangular (Fig. 24E). Lateral lobe moderately broad basally, evenly tapered and slightly curved to rounded apex which has series of marginal setae (Fig. 24F).

Female genitalia. Gonocoxosternite with apical portion broadly triangular, medial margin slightly concave, apical portion very large and broadly lobed (Fig. 40). Gonocoxa broad, apically broadly rounded, evenly tapered anteriorly to short apodeme (Fig. 40). Bursa short, broad; spermathecal duct very slender and elongate, expanded to receptacle which is semispherical; spermatheca elongate, slender and curved, without spermathecal spine; fertilization duct short, slender (Fig. 40).

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

Variation. Specimens vary in coloration with some specimens darker and others lighter.

Etymology.

This species is named maculatus, Latin for “spotted,” for the maculate coloration on the elytra in specimens.

Distribution.

Hydrodessus maculatus is known from Amazonas, Venezuela and Region IX, Guyana (Fig. 45).

Habitat.

Specimens were collected "seined from rocks in rapids" and "netted along margins" of the Rio Baria. They have also been found in creeks and at a blacklight in a rainforest.

Specimens.

Holotype: ♂ in MIZA labeled, "VENEZUELA, T.F.Amaz. Cerro de la Neblina Basecamp, 140 m. 0°50'N, 66°10'W 20 February 1985/ Netted along margins of Rio Baria P.J. & P.M.Spangler, R.Faitoute,W.Steiner/ HOLOTYPE Hydrodessus maculatus Miller, 2016 [red label with black line border]."

Paratypes, 110 total. Venezuela; Amazonas, Cerro de al Neblina, basecamp, 0.833°N, 66.167°W, 21 Feb 1985, muddy oxbow pond, 140m, P.J. Spangler, P.M. Spangler, R. Faitoute and W. Steiner (51, USNM, KUNHM, MIZA, MSBA); same, but 20 Feb 1985, netted along margins of Rio Baria (51, USNM, KUNHM, MIZA, MSBA); same, but 20 Feb 1985, seined from rocks in rapids of Rio Baria (4, USNM); same, but 6 Feb 2013, blacklight in rainforest clearing near Rio Baria (1, USNM). Guyana; Region IX, road to Parabara, creek crossing at Mushal Wao, 2.161°N, 59.292°W, 1 Sep 2013, creek margins, 268m, Short, Isaacs, Salisbury (2, KUNHM, SEMC0964975, SEMC0964987).