A review of the Neotropical genus Bidessodes Regimbart, 1895 including description of four new species (Coleoptera, Adephaga, Dytiscidae, Hydroporinae, Bidessini) Author Miller, Kelly B. text ZooKeys 2017 658 9 38 http://dx.doi.org/10.3897/zookeys.658.10928 journal article http://dx.doi.org/10.3897/zookeys.658.10928 1313-2970-658-9 FE249A993CC041689DFFBE2575F4481B FE249A993CC041689DFFBE2575F4481B Bidessodes melas sp. n. Figs 16-20, 98 Type locality. Venezuela, Amazonas State, Comunidad Cano 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 Cano Gato Rio Sipapo: 16.i.2009; leg. Short, Miller, Camacho, Joly & Garcia VZ09-0116-01X: along stream/ SM0842862 KUNHM- ENT [barcode label]/ HOLOTYPE Bidessodes melas Miller, 2016 [red label with black line border]." Paratypes, 66, labeled same as holotype except with different specimen barcode labels and each with "... PARATYPE Bidessodes melas Miller, 2016 [blue label with black line border]." Diagnosis. This species does not have a carinate prosternum in either male or female. The prosternal process is longitudinally slightly convex and relatively narrow with the lateral margins distinctly convergent to a pointed apex. The male mesotibia is unmodified. The male metatrochanter and metafemur are unmodified (Fig. 20) and the male last abdominal ventrite is unmodified. The male median lobe in lateral aspect is very small basally with the apical portion long, slender and evenly curved to a narrowly rounded apex (Fig. 17). In ventral aspect the median lobe is slender basally with the lateral margins expanded apically, divided into two long, slender curved rami that bend medially apically (Fig. 18). The basal segment of the lateral lobe is broadly obliquely triangular (Fig. 19). The apical segment is broad and obliquely subrectangular with the apex obliquely subtruncate (Fig. 19). Externally, Bidessodes melas 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 male genitalia. The slender, elongate, longitudinally emarginate male median lobe and broad and uniquely shaped lateral lobes (Figs 17-19) are unlike any other species in the genus. This is also one of the smallest species in the genus. Description. Measurements. TL = 1.6-1.7 mm, EW = 0.8-0.9 mm, PW = 0.7-0.8 mm, HW =0.5-0.6 mm, ED = 0.3-0.4 mm, TL/EW = 2.1-2.3, HW/ED = 1.7-1.8. Body shape elongate oval, pronotum widest medially, width somewhat less than greatest width of elytra, lateral outline discontinuous between pronotum and elytron. Coloration (Fig. 16). Head and pronotum yellow, posterior margin of pronotum medially narrowly brown. Elytron with base color brown with diffuse, transverse pale regions anteriorly, medially and at apex (Fig. 16); surface slightly but distinctly purplish iridescent. Head appendages, legs and ventral surfaces yellow to yellow-orange. Sculpture and structure (Fig. 16). Head with dorsal surface smooth and shiny, with extremely fine micropunctures. Pronotum (Fig. 16) 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. 16) very broadly curved laterally; shiny, finely microreticulate across surface, impunctate. Prosternal process elongate, basally broad and posteriorly convergent to narrowly 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. Abdominal ventrites smooth, impunctate; ventrite VI smooth, evenly convex, apically pointed. Male genitalia. Median lobe in lateral aspect with small basal portion, apical portion elongate, slender, broadly and evenly curved to narrowly rounded apex (Fig. 17); median lobe in ventral aspect deeply bifid into two elongate, slender rami, apically pointed and with apices curved towards each other apically (Fig. 18); lateral lobe in lateral aspect very robust, basal and apical portions similar in length and width, apical portion broad, apically truncate and toothed (Fig. 19). Sexual dimorphism. Male pro- and mesotarsomeres I-III broader than in female with extensive ventral adhesive setae. Male and female otherwise similar. Variation. Specimens vary in the intensity and extent of elytral maculae which are not strongly evident in any specimens. Etymology. This species is named melas , Greek for "black" after one of the four horsemen of the apocalypse. Distribution. This species is known only from southwestern Venezuela (Fig. 98). Habitat. The type series was collected from leaf pack in slow areas along a sandy forest stream.