Hydrodessus tenuatus, 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 : 113-115

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus tenuatus sp. n. Figs 7B, 34, 45

Type locality.

Suriname, Sipaliwini Districct, Camp 1 on Kutari River, 2.175°N, 56.787°W.

Diagnosis.

This species is part of a group including Hydrodessus maculatus , Hydrodessus latotibialis , and Hydrodessus phyllisae that have the lateral elytral carina long (half or more the length of the elytron) (Fig. 34B), the prosternal process very broad (length/width <2) (Fig. 34C), and the metaventral platform (the region between the metaventrite carinae) conspicuously constricted near the base of the metaventral process and fairly broadly divergent posteriorly (Fig. 34C). Hydrodessus tenuatus differs from Hydrodessus maculatus in having the elytra uniformly brown red (without maculae) and from Hydrodessus latotibialis and Hydrodessus phyllisae in having the pro- and mesotarsi relatively slender (not expanded with a subapical emargination). The male median lobe is basally triangular, curved at the base of the apical portion, and slender apically (Fig. 34D). The apex is slender and slightly curved to a pointed apex (Fig. 34D). In ventral aspect the laterla margins are broadly curved to moderatley rounded apex (Fig. 34E). The lateral lobe is broad basally, linear and evenly narrowed in apical half to rounded apex (Fig. 34F).

Description.

Measurements. TL = 2.8 mm, GW = 1.4 mm, PW = 1.2 mm, HW = 0.9 mm, EW = 0.5 mm, TL/GW = 2.0, HW/EW = 1.6. Body moderately robust, apically pointed, lateral outline moderately discontinous between pronotum and elytron (Fig. 34A).

Coloration (Fig. 34A). Head and pronotum orange. Elytra uniformly brown-red (Fig. 34A). Antennae and palps orange. Legs and ventral surfaces orange-red, darker near midline of metacoxa and on basal abdominal ventrite.

Sculpture and structure. Head moderately broad, anterior clypeal margins broadly rounded; surface shiny, microreticulate with numerous fine punctures; eyes large. Pronotum cordate, widest near anterior margin (Fig. 34A); lateral bead fine and distinct throughout length; surface shiny, covered with fine, indistinct punctures. Elytra elongate, apically pointed (Fig. 34A); lateral carina distinctive, elongate, extending about 3/5 length of elytron (Fig. 34B); surface shiny with punctures fine over entire surface, without lines on disc. Prosternum medially somewhat swollen, with fine medial carina; prosternal process moderately broad, widest at anterior angles, lateral margins slightly laterally compressed, deeply excavated medially, apically broadly truncate (Fig. 34 C). Metaventrite with anterior process moderately broad, apically rounded, medially distinctly excavated; metasternal carinae distinctive across metasternum, anteriorly approximated, posteriorly distinctly divergent to posterior margin, terminating at anterior ends of metacoxal lines (Fig. 34C); metaventrite with lateral surface densely 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 densely punctate; metacoxal lines subparallel, anteriorly slightly divergent (Fig. 34C). Abdomen covered with fine punctures; VI apically narrowly rounded.

Male genitalia. Median lobe bilaterally symmetrical, in lateral aspect narrow basally, slender and evenly and broadly curved, medially slightly expanded, subapically slightly narrowed and curved to sharply pointed apex (Fig. 34D); in ventral aspect moderately broad, lateral margins broadly curved, apically broadly pointed (Fig. 34E). Lateral lobe broad basally, evenly narrowed apically to narrowly rounded apex, with small series of setae apically (Fig. 34F).

Female genitalia. Not examined.

Sexual dimorphism. Only the male holotype examined.

Variation. Only the male holotype examined.

Etymology.

This species is named tenuatus, Latin for “narrow,” for the relatively narrow mesotibia in specimens.

Distribution.

This species is known only from one locality in Suriname near the Kutari River (Fig. 45).

Habitat.

The one known specimen was collected at a UV light at night.

Specimens.

Only the holotype male was examined in NZCS labeled "SURINAME: Sipaliwini District 2°10.521'N, 56°47.244'W; 228 m Camp 1, on Kutari River leg. A.E.Z.Short; UV-light 19-24.vii.2010; SR10-0819-LT1 2010 CI-RAP Survey; SEMC0915670 KUNHM-ENT [barcode label]/ Hydrodessus sp. [handwritten] det. A.E.Z. Short 2011/ HOLOTYPE Hydrodessus tenuatus Miller, 2016 [red line with black line border]."

Species removed from Hydrodessus