Hydrodessus brasiliensis (Guignot, 1957)

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 : 64-66

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus brasiliensis (Guignot, 1957) Figs 11, 42

Brinckius brasiliensis Guignot, 1957: 40.

Hydrodessus brasiliensis , Young 1969: 2; 1970: 158; Spangler 1985: 88; Biström 1988: 37; Nilsson 2001: 236.

Type locality.

Brazil, Pará State, Cachimbo.

Diagnosis.

Hydrodessus brasiliensis is characterized by being concolorous dark red-brown (Fig. 11A). The lateral elytral carina is prominent, extending to about 1/2 length of elytron (Fig. 11B). The pronotum is about the same width as the greatest distance across the elytra (Fig. 11A). Ventrally, the prosternal process is broad but has distinctive laterally-directed lobes anteriorly and is constricted medially (Fig. 11C). The metaventral platform is not strongly constricted and the metaventrite carinae are moderately divergent posteriorly with the posterior apices ending near the anterior apices of the metacoxal lines (Fig. 11C). The male median lobe in lateral aspect is broadly triangular basally with the apical portion broadly curved, slender and apically slightly sinuate, slender and sharply pointed (Fig. 11D). The median lobe in ventral aspect is bilaterally symmatrical and nearly parallel-sided with the apex broadly rounded (Fig. 11E). The lateral lobe is relatively narrow, medially curved and has the apical portion gently tapered to broadly rounded apex (Fig. 11F). There is a setal margin extending around much of the apical half (Fig. 11F). The species is not particularly similar to others in the genus.

Description.

Measurements. TL = 3.0 mm, GW = 1.3 mm, PW = 1.2 mm, HW = 0.9 mm, EW = 0.5 mm, TL/GW = 2.3, HW/EW = 1.8. Body elongate, apically pointed, lateral outline moderately discontinuous between pronotum and elytron (Fig. 11A).

Coloration (Fig. 11A). Head, pronotum and elytra evenly dark red-brown, (Fig. 11A). Antennae, palps and legs red-brown. Venter dark red-brown throughout.

Sculpture and structure. Head broad, anterior clypeal margin broadly curved; surface shiny, covered with dense, fine punctures; eyes moderately large. Pronotum slightly cordate, widest anterior of middle (Fig. 11A); lateral bead very fine and continuous; surface with fine punctation, mediolaterally with punctures somewhat connected and irregular rugose. Elytra elongate, apex pointed, slightly constricted subapically (Fig. 11A); lateral carina sharp and distinct, extending to about half elytral length (Fig. 11B); surface covered with fine, relatively dense punctation. Prosternum medially tectiform and setose; prosternal process broad, distinctly constricted medially with prominent lateral lobes anteriorly, distinctly impressed longitudinally, apex broadly truncate (Fig. 11C). Metaventrite elongate, slightly impressed longitudinally, apex narrowly rounded; metasternal carinae distinctive, moderately closely approximated anteriorly, distinctly divergent posteriorly (Fig. 11C); other surfaces covered with fine, dense punctation. Legs covered with fine punctures on most surfaces; metatibia with distinctive brush of dense, elongate setae on postero-apical surface; pro- and mesotibiae moderately broad; metatrochanter distinctly offset, apically rounded; metacoxa evenly covered with fine punctures; metacoxal lines relatively closely approximated, subparallel (Fig. 11C). Abdomen evenly covered with fine punctures; apex of VI medially broadly pointed.

Male genitalia. Median lobe bilaterally symmetrical, in lateral aspect with basal portion broad, medially broadly curved and slender, apically slender and narrowed to slightly but distinctly sinuate, sharply pointed apex (Fig. 11D); in ventral aspect moderately broad, lateral margins subparallel to rounded apex (Fig. 11E). Lateral lobe moderately broad basally, apically narrow with margins subparallel to narrowly rounded apex, apical margins with distinctive series of setae (Fig. 11F).

Female genitalia. Not examined.

Sexual dimorphism. Only the male holotype was examined.

Variation. Only the male holotype was examined.

Distribution.

Hydrodessus brasiliensis is known only from Cochimbo, Para, central Brazil (Fig. 42).

Habitat.

Nothing is known of the habitat of the species.

Discussion.

Only the male holotype specimen was examined of this species.

Specimens.

The holotype male specimen is in MZSP labeled, "Type [red label with black line border]/ ♂/Brasilien, Para Cochimbo X.1955 Pereira [black line border]/ 31921/ F. Guignot det., 1956 Brinckius brasiliensis sp. n. Type ♂ [handwritten]."