Bidessodes leukus, Miller, Kelly B., 2017

Miller, Kelly B., 2017, A review of the Neotropical genus Bidessodes Regimbart, 1895 including description of four new species (Coleoptera, Adephaga, Dytiscidae, Hydroporinae, Bidessini), ZooKeys 658, pp. 9-38 : 19

Bidessodes leukus sp. n. Figs 11-15, 97

Type locality.

Venezuela, Amazonas State, Comunidad Caño Gato, Rio Sipapo 4°58.838'N, 67°44.341'W.

Type material.

Holotype in MIZA, male labeled, "VENEZUELA: Amazonas State 4°58.838'N, 67°44.341'W: 95m Comunidad Caño Gato Rio Sipapo: 16.i.2009; leg. Short, Miller, Camacho, Joly & Garcia VZ09-0116-01X: along stream/ SM0842868 KUNHM- ENT [barcode label]/ HOLOTYPE Bidessodes leukus Miller, 2016 [red label with black line border]."

Diagnosis.

This species does not have a carinate prosternum in either male or female. The prosternal process is broad, broadly convex, with the lateral margins convergent to the rounded apex. The male mesotibia is unmodified. The male metatrochanter and metafemur are unmodified (Fig. 15) and the male abdominal ventrite VI is unmodified. The male median lobe in lateral aspect is very broad basally with the apical portion short and abruptly curved (Fig. 12). In ventral aspect the median lobe is very broad with undulate lateral margins and the apex broad and medially emarginate (Fig. 13). The basal segment of the lateral lobe is short and subquadrate with the proximate margin toothed (Fig. 14). The apical segment is elongate and T-shaped with the apical margin broadly curved and with a series of setae (Fig. 14). Externally, Bidessodes leukus is similar to many other species of Bidessodes with relatively unmodified ventral surfaces and legs in males or females. The main difference between this species and others is the unique male genitalia. The male median lobe and lateral lobes (Figs 12-14) are unlike any other species in the genus. In particular, the median lobe is very broad in ventral aspect (Fig. 12) and robust and strongly curved in lateral aspect (Fig. 13).

Description.

Measurements. TL = 2.4 mm, EW = 1.1 mm, PW = 1.0 mm, HW = 0.7 mm, ED = 0.4 mm, TL/EW = 2.3, HW/ED = 1.9. Body shape elongate oval, pronotum widest medially, width somewhat less that greatest width of elytra, lateral outline discontinuous between pronotum and elytron, posteriorly somewhat attenuate.

Coloration (Fig. 11). Head and pronotum yellow, posterior margin of pronotum medially narrowly brown. Elytron with base color brown with very weakly differentiated, diffuse, transverse pale regions anteriorly, medially and at apex (Fig. 11); surface not iridescent. Head appendages, legs and ventral surfaces yellow to yellow-orange.

Sculpture and structure (Fig. 11). Head with dorsal surface smooth and shiny, with extremely fine micropunctures. Pronotum (Fig. 11) smooth and shiny with few broadly dispersed micropunctures; lateral margins broadly rounded, pronotum broadest medially, slightly constricted at posterior angles, about same width as greatest width of elytra; basal striae moderately well impressed, extending to nearly 1/2 distance across pronotum. Elytron (Fig. 11) very broadly curved laterally; shiny, finely microreticulate across surface, impunctate. Prosternal process basally broad and posteriorly slightly convergent to broadly rounded apex, lateral margins broadly rounded; surface approximately flat. Metaventrite process anteriorly produced with weak lateral carinae that do not extend posteriorly; surface of metaventrite smooth and shiny, not carinate or otherwise modified. Metacoxa with lateral portions shiny, not punctate; metacoxal lines elongate, subparallel, apically distinctly convergent. Abdominal ventrites smooth, impunctate; ventrite VI smooth, evenly convex, apically broadly pointed.

Male genitalia. Median lobe in lateral aspect with basal portion broad and irregular, apical portion robust, short, abruptly curved at nearly right angle medially, apically narrowed to elongate pointed apex (Fig. 12); median lobe in ventral aspect very broad, apically with lateral margins broadly expanded into lobes laterally, apex bifid (Fig. 13); lateral lobe in lateral aspect irregular, basal portion broad and short, basally with lobes and teeth, apical portion elongate and T-shaped, apex broadly expanded laterally, apical margin curved (Fig. 14).

Sexual dimorphism. Females not examined, but male pro- and mesotarsomeres I-III laterally expanded with ventral adhesive setae, similar to other Bidessodes species that exhibit this dimorphism.

Variation. Only a single male specimen was examined.

Etymology.

This species is named leukus , Greek for “white” after one of the four horsemen of the apocalypse.

Distribution.

Bidessodes leukus is known only from southwestern Venezuela (Fig. 97).

Habitat.

The type was collected from slow areas along a sandy forest stream with extensive leaf pack.