Hydrodessus surinamensis Young, 1970

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 : 110-113

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus surinamensis Young, 1970 Figs 33, 44

Hydrodessus surinamensis Young, 1970: 153; Spangler 1985: 88; Biström 1988: 37; Nilsson 2001: 236.

Type locality.

Suriname, Carolina Creek, 10km S Zanderij.

Diagnosis.

Hydrodessus surinamensis has a characterstic coloration with the head and pronotum yellow and the elytra brown with distinct pale yellow maculae and lateral margins (Fig. 33A). The large subbasal macula exends to the lateral margin and, in a narrow subhumeral line, to the anterior margin (Fig. 33A). The apex of the elytron and a distinctive macula at about 3/4 elytral length are also yellow (Fig. 33A). The lateral elytral carina is short and distinctly only near humeral angle (Fig. 33B). The prosternal process is relatively narrow but has distinct laterally-directed lobes anteriorly (Fig. 33C). The metaventral process is narrowly rounded and the metaventrite carinae are indistinct, mainly represented by impunctate lines that diverge somewhat posteriorly (Fig. 33C). The male median lobe is simple and bilaterally symmetrical (Fig. 33E). In lateral aspect the median lobe is basally elongate triangular (Fig. 33D). The apical portion is shallowly curved to a pointed apex (Fig. 33D). In ventral aspect the median lobe is slender and narrowed medially to elongate, slender, pointed apex (Fig. 33E). The lateral lobe is slender and elongate-curved (Fig. 33F).

Description.

Measurements. TL = 2.3-2.5 mm, GW = 1.1 mm, PW = 0.9-1.0 mm, HW = 0.7-0.8 mm, EW = 0.4 mm, TL/GW = 2.2, HW/EW = 1.8. Body shape elongate, lateral margins strongly discontinous between pronotum and elytron (Fig. 33A).

Coloration (Fig. 33A). Head and pronotum yellow. Elytra brown to yellow-brown with three regions of yellow: 1) one large basal irregular macula extending medially to near suture, covering anterolateral region except small, round, brown spot, 2) one moderately large, subapical macula, and 3) apex. Antennae, palps, legs and other ventral surfaces yellow.

Sculpture and structure. Head broad, apically subtruncate in dorsal aspect, clypeal margin concave in anterodorsal aspect; surface very finely punctate; eyes large, conspicuous. Pronotum cordate, widest anterior of middle (Fig. 33A); lateral bead fine, obscured posteriorly; surface finely punctate. Elytra elongate, laterally evenly and broadly curved (Fig. 33A); lateral carina rounded, indistinct and limited to near humeral angle; elytral surface covered with fine punctures. Prosternum evenly rounded medially, not carinate; prosternal process elongate, broadest at base with laterally expanded lobes, posteriorly slender, lateral carinae proximate and covergent to narrowly rounded apex (Fig. 33C). Metaventrite with anterior process slender, carinae not strongly developed, posteriorly represented by low, rounded ridges ending distinctly mediad of anterior ends of metacoxal lines (Fig. 33C); surfaces covered with irregular punctures. Legs with surfaces covered with fine punctures; pro- and mesotibiae moderately broad; metatrochanter strongly offset from metafemur, apex broadly rounded; metatibia with posteroapical brush of setae; metacoxa covered with irregular punctures; metacoxal lines moderately broadly separated, straight and distinctly divergent anteriorly (Fig. 33C). Abdomen covered with irregular punctation; abdominal ventrite VI terminating in minute, medial, spinous lobe.

Male genitalia. Median lobe bilaterally symmetrical, in lateral aspect evenly but not strongly curved, with base small and subtriangular, apical portion elongate, slender, and evenly curved, apex slender and pointed (Fig. 33D); in ventral aspect slender and parallel sided in basal half, abruptly narrowed submedially and slender in apical half to narrowly rounded apex (Fig. 33E). Lateral lobe relatively narrow and evenly curved to slightly oblique apex (Fig. 33F).

Female genitalia. Not examined.

Sexual dimorphism. Male pro- and mesotarsi I–III more broadly expanded than female and ventrally with several large adhesive setae.

Variation. Specimens vary somewhat in extent of the maculae on the elytra surface.

Distribution.

This species is known from Suriname and Amazonas, Venezuela (Fig. 44).

Habitat.

This species has been collected from waterholes in a forest stream, tiny forest pools, large detrital pools, a large, sandy creek, and along a stream.

Discussion.

The holotype (in Rijksmuseum van Natuurlijke Historie, Leiden, Young 1970) was not examined, but nine paratypes (in FSCA) were, and the identity of this species is clear.

Specimens.

Specimens examined, 17 total. Suriname, Carolina Creek, 10km from Zanderij, 5.4°N, 55.183°W, 18 Nov 1962, waterhole in forest stream, B. Malkin (7, FSCA, paratypes); District XXV, Krakka-Phedra Road, 5.333°N, 55.086°W, 18 Nov 1962, tiny forest pool, B. Malkin (2, FSCA, paratypes); Sipaliwini District, Camp 1, Upper Palumeu, 2.477°N, 55.629°W, 14 Mar 2012, large sandy creek, 275m, A. Short (1, KUNHM, SEMC1088261); same except 10 Mar 2012, large detrital pools, 275m, A. Short (1, KUNHM, SEMC1089221). Venezuela, Amazonas, Communidad Caño Gato, on Rio Sipapo, 4.981°N, 67.739°, 16 Jan 2009, along stream, 95m, Short, Miller, Camacho, Joly and García (5, KUNHM, SM0843163, SM0843182, SM0843268, SM0843269, SM0843299).