Hydrodessus pereirai (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 : 100

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus pereirai (Guignot, 1957) Figs 4, 45

Brinckius pereirai Guignot, 1957: 41.

Hydrodessus pereirai , Young 1969: 2; 1970: 157; Spangler 1985: 88; Biström 1988: 37; Nilsson 2001: 236.

Type locality.

Brazil, Pará State, Cachimbo.

Diagnosis.

Specimens of this species are among the largest Hydrodessus (TL = 3.9). The lateral elytral carina is distinctly present only at the humeral angle, though it can be traced further along the elytron out to about 1/4 ts length (Fig. 4B), the dorsal and ventral coloration is approximately evenly dark red (Fig. 4A), the lateral pronotal margins are broadly curved (Fig. 4A), the prosternal process is broad with distinctive lateral lobes anteriorly (Fig. 4C), the metaventrite carinae are moderately distinctive, not strongly constricted, and moderately divergent posteriorly (Fig. 4C), the metacoxal lines are broadly separated and somewhat divergent anteriorly (Fig. 4C). Hydrodessus pereirai is superficially very similar to Hydrodessus brevis in coloration, shape, and general structures, but that species has a maximum length of about 2.5mm. Unfortunately, males are not known for Hydrodessus pereirai so the usually definitive character system of male genitalia is not available for comparison.

Description.

Measurements. TL = 3.8 mm. Body elongate, apically pointed, lateral margin strongly discontinuous between pronotum and elytron (Fig. 4A).

Coloration (Fig. 4A). Head, pronotum and elytra evenly dark red. Antennae and palps yellow-red. Legs yellow-brown to yellow-red. Venter dark red, yellow-red at apex of abdomen.

Sculpture and structure. Head broad, anterior margin slightly flattened medially; surface covered with minute punctures; eyes moderately small. Pronotum cordate, widest anterior to middle (Fig. 4A); lateral bead fine, but distinct; surface covered with fine punctation. Elytra long, apically pointed; lateral carina distinctive, extending about 1/3 length of elytron (Fig. 4B); surface covered with minute punctation. Prosternum medially with broad, rounded ridge; prosternal process broad, broadest at anterior laterally expanded lobes, lateral margins slightly convergent to slightly curved, subtruncate apex, medially distinctly impressed (Fig. 4A). Metaventrite with anterior process elongate, moderately slender, flattened; metasternal carina distinctive, straight from sides of process, evenly divergent across Metaventrite (Fig. 4C); surfaces covered with minute punctures. Legs with most surfaces covered with fine punctation; pro- and mesotibiae slender; metatibia with distinctive brush of dense, elongate setae on postero-apical surface; metatrochanter distinctly offset, apically narrowly rounded; metacoxa with surface covered with minute punctures; metacoxal lines broadly separated, slightly sinuate and divergent anteriorly (Fig. 4C). Abdomen covered with minute punctures; abdominal ventrite VI with apex slightly pointed.

Female genitalia. Not examined.

Sexual dimorphism. Only one, female specimen (the holotype) was examined.

Variation. Only one, female specimen (the holotype) was examined.

Distribution.

The species is known only from the type locality in Para, central Brazil (Fig. 45).

Habitat.

Nothing is known of the habitat of this species.

Specimens.

Only the female holotype in MZSP was examined, labeled, "Type [red label with black border]/ Brasilien, Para Cachimbo X.1955 Pereira/ F. Guignot det., 1956 Brinckius Pereirai Type ♀ [handwritten]/ 31901."