Bidessonotus valdezi 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 : 108

Taxon classification Animalia Coleoptera Dytiscidae

Bidessonotus valdezi Miller sp. n. Figs 11, 18, 30

Type locality.

Guyana, Region 6, Upper Berbice, ca 1km S Basecamp 1, 4°09.289'N, 58°12.274'W.

Diagnosis.

Specimens of Bidessonotus valdezi are relatively pale brown with the elytral maculae indistinct and vague. The prosternal process is lanceolate, shallowly sulcate and apically pointed. The apical blade of the male median lobe is broad with a moderately developed apicoventral triangular prominence, the distal margin sublinear, the proximal margin obliquely linear, and the dorsal margin narrowly truncate (Fig. 18a). The lateral lobes are distinctive, the right lateral lobe has the apical segment long, slender and apically rounded (Fig. 18a). The left lateral lobe is shorter, broader with the lateral margins evenly convergent to a rounded apex (Fig. 18c). Females have the apicolateral margin of the elytron unmodified. The male median lobe is somewhat similar in shape to the species Bidessonotus peregrinus J. Balfour-Browne, but that species (known from Panama) is smaller (<1.8 mm) and there are some differences in the male genitalia. In Bidessonotus peregrinus the apical blade of the median lobe is much more narrow and the lateral lobes are broader with the apical segments on each side differently shaped between the two species. Specimens of Bidessonotus valdezi are not dorsally iridescent, whereas females of Bidessonotus peregrinus usually are.

Description.

Measurements. TL = 1.8-1.9 mm, GW = 0.9 mm, PW = 0.7 mm, HW = 0.5 mm, EW = 0.3 mm, TL/GW = 2.0-2.1, HW/EW = 1.8. Body shape elongate oval, lateral outline discontinuous between pronotum and elytron.

Coloration (Fig. 11). Head, including all appendages and ventral surface, entirely pale yellow to yellow-orange. Pronotum entirely yellow. Elytron base color brown with broad, diffuse, somewhat transverse slightly paler regions, margin of regions vague and indistinct (Fig. 11); without purplish iridescence. Prosternal surface yellow; other thoracic ventrites orange except metacoxa darker orange.

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

Male genitalia. Apex of median lobe in lateral aspect with apical blade moderately broad, with anteroventral triangular prominence, dorsal margin truncate, proximal margin obliquely curved (Fig. 11a). Lateral lobe in lateral aspect with apical segment about as long as proximal segment; apical segment relatively narrow, apex rounded (Fig. 11b).

Variation. Specimens vary in the extent and intensity of the elytral fasciae and maculations. In some specimens the lighter regions of the elytra are somewhat more intensely pale and slightly more distinctly defined.

Sexual dimorphism. With typical sexual dimorphisms for Bidessonotus species. Females with dorsal surface more matte than in males.

Etymology.

The species is named valdezi after the good friend of the author and eminent biologist, Dr. Ernest Valdez.

Distribution.

Known from Guyana and Suriname (Fig. 30).

Habitat.

Specimens have been found in "muddy detrital pools" in a drying creek bed,"detritus pools" in a dry creek bed, and a "pooled up creek."

Type material.

Holotype in CSBD, male labeled, "GUAYANA: Region 6 4°09.289'N, 58°12.274'W, 108m Upper Berbice, ca. 1 km S. Basecamp 1 detrius pools in dry creekbed leg. Short, Salisbury, La Cruz 26.ix.2014; GY14-0825-01D/ SECM1358746 KUNHM-ENT [barcode label]/ HOLOTYPE Bidessonotus valdezi Miller, 2016 [red label with black line border]." paratypes 12, Guyana: Region 6, Upper Berbice, Basecamp 1, 4°09.289'N, 58°12.274'W, 72m, muddy detrital pools in drying creekbed near camp, Short, Salisburg, La Cruz, legs., 21 Sep 2014, GY14-0821-02A (2, SEMC); Region 6, Upper Berbice, ca 1km S Basecamp 1, 4°09.241'N, 58°10.627'W, detritus pools in dry creekbed, Short, Salisbury, La Cruz, legs, 26 Sep 2014, GY14-0925-010 (7, SEMC); Region 6, Upper Berbice, 3km W Basecamp 1, 4°09.297'N, 58°00.431'W, pooled up creek, Short, Salisbury, La Cruz, legs, GY14-0923-01A (3, SEMC). Suriname: Sipaliwini, Camp 2, on Sipaliwini river, 2.182°N, 56.787°W, 28 Aug 2010, Short & Kadosoe (5, SEMC); Sipaliwini, Camp 3, Wehepai, 2.362°N, 56.697°W, 03 Sep 2010, Short & Kadosoe (16, SEMC).