Bidessonotus palecephalus Miller

Miller, Kelly B., 2016, New species of Bidessonotus Regimbart, 1895 with a review of the South American species (Coleoptera, Adephaga, Dytiscidae, Hydroporinae, Bidessini), ZooKeys 622, pp. 95-127 : 101

Taxon classification Animalia Coleoptera Dytiscidae

Bidessonotus palecephalus Miller sp. n. Figs 7, 14, 30

Type locality.

Venezuela, Guarico, N of Palenque, 9.113°N, 66.993°W.

Diagnosis.

This is a relatively pale brown species. The head color in specimens of Bidessonotus palecephalus is overall pale, unlike Bidessonotus melanocephalus which has the base of the head darkened. The prosternal process is flat and apically pointed. Females have the apicolateral elytral margins developed into a prominent lobe (Fig. 7b). Males of this species have the median lobe shape similar to those of Bidessonotus melanocephalus with a tooth medially on the dorsal margin near the apical base of the shaft as well as a tooth at each end of the distal margin (Fig. 14a), though the overall shapes are different in the two species. The lateral lobes are moderately similar in shape with the apical segments broad, but the right apical segment (Fig. 14b) is apically broadly rounded and the left apical segment is distinctly angulate along the ventral margin (Fig. 14c).

Description.

Measurements. TL = 1.9-2.0 mm, GW = 1.0 mm, PW = 0.8-0.9 mm, HW = 0.5-0.6 mm, EW = 0.3 mm, TL/GW = 1.8-2.0, HW/EW = 1.8-2.0. Body shape elongate oval, lateral outline discontinuous between pronotum and elytron.

Coloration (Fig. 7). Head, including all appendages and ventral surface, entirely pale yellow to yellow-orange. Pronotum yellow to yellow-orange. Elytron base color brown with large irregular yellow fasciae and maculae (Fig. 7); dorsal surfaces not purplish or iridescent in either sex. Ventral surfaces, including all legs and mouthparts, yellow, slightly darker along some sutures.

Sculpture and structure. Head with anterior clypeal margin slightly thickened, evenly rounded; surface smooth and shiny; antennomeres III-X moderately broad, slightly asymmetrical. Pronotum widest near posterior angles, lateral margins evenly curved; basal striae strongly impressed, broad, extending anteriorly more than halfway across surface; posterior margins distinctly undulate; surface overall slightly matte, but shiny, surface mediad of striae distinctly punctate. Elytron with lateral margins broadly curved; basal stria distinct, elongate, well impressed basally; surface of elytron covered with fine punctation, surface between punctures shiny. Prosternal process elongate, apically pointed, surface broadly convex throughout length. Metaventrite with distinctive carinae extending from medial apex of metaventrite process posteriorly to near posterior margin at anterior terminus of metacoxal lines; surface of metaventrite shiny with few micropunctures. Metacoxae shiny with few micropunctures; metacoxal lines distinct, broad, broadly curved with external surface convex, slightly convergent anteriorly. Basal abdominal ventrites punctate, other surfaces of abdominal ventrites smooth, relatively shiny.

Male genitalia. Apex of median lobe in lateral aspect with blade elongate, with apicoventral tooth, submedial broad tooth on distal margin and broad tooth along proximal margin, dorsal margin broad and obliquely truncate (Fig. 14a, d). Right lateral lobe in lateral aspect with apical segment about as long as proximal segment; apical segment apically broadly expanded, apex broadly rounded (Fig. 14b) left lateral lobe with apical segment very broad, apically very broadly rounded and with a distinct angulation along the ventral margin (Fig. 14c).

Variation. Specimens vary in the extent and intensity of the elytral fasciae and maculations.

Sexual dimorphism. With typical dimorphism found in Bidessonotus . Males with apicolateral margin of elytron evenly curved (Fig. 7a); females apically shortened, more abruptly rounded with distinctive, broadly rounded posterolateral expansion (Fig. 7b). Males with elytra shiny and smooth between punctures; females with elytra opaque and microreticulate.

Etymology.

The species is named palecephalus from the Greek words pale, meaning “pale,” and cephalus, meaning “head,” for the pale head of specimens in comparison with the somewhat similar species Bidessonotus melanocephalus .

Distribution.

The species is known from Apure and Guarico, Venezuela (Fig. 30).

Habitat.

Nothing is known of the habitat of this species.

Type material.

Holotype in MIZA, male labeled, "VENEZUELA: Guarico State 9.113°N, 66.993°W, 152m, Stream @ [sic] road crossing, N. of Palenque; 6.i.2009; leg. Short, García, Miller, Camacho, Joly VZ09-0108-03X; stream/ SEMC0854983 KUNHM-ENT [barcode label]/ HOLOTYPE Bidessonotus palecephalus Miller, 2016 [red label with black line border]." Paratypes, 31 total from the following localites: Venezuela: Apure, between La Ye and Bruzual, 7.644°N, 69.300°W, 18 Jan 2009, Short, Camacho, Miller (6, SEMC); Guarico, N of Palenque, 9.113°N, 66.993°W, 08 Jan 2009, Short, Camacho, Garcia, Joly, Miller (25, SEMC).