Hydrodessus fasciatus, Miller, Kelly B., 2016

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 : 74-75

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus fasciatus sp. n. Figs 16, 45

Type locality.

Brazil, Rio Gurupi, 12-15km E Caninde-Igarape Coraci.

Diagnosis.

This species is dorsally dark brown with distinctive, irregular fasciae on the elytra (Fig. 16A). The fasciate are somewhat linear-sided making the pale regions subrectangular (Fig. 16A). The lateral elytral carina is absent (Fig. 16B). The prosternal process is elongate and somewhat slender with the lateral margins subparallel (Fig. 16C). The anterior metaventrite process is moderately slender and medially impressed (Fig. 16C). The metaventrite carinae are distinct only anteriorly (Fig. 16C). The male median lobe in lateral aspect has a small basal region (Fig. 16D). The apical portion is evenly curved along the dorsal margin, but thickened subbasally and subapically along the ventral margin (Fig. 16D). The apex is elongate, slender and narrowly rounded apically (Fig. 16D). In ventral aspect the median lobe is slender, bilaterally asymmetrical and apically narrowly and obliquely rounded (Fig. 16E). The lateral lobe is moderately slender and broadly curved to a rounded apex (Fig. 16F). The species is perhaps most similar to Hydrodessus siolii in body shape and structure, but that species has a different color pattern and the male genitalia are distinctive in each species.

Description.

Measurements. TL = 2.7-2.8 mm, GW = 1.3 mm, PW = 1.0-1.1 mm, HW = 0.8-0.9 mm, EW = 0.4 mm, TL/GW = 2.1-2.2, HW/EW = 1.9-2.1. Body shape slender, elongate, apically pointed, lateral margins distinctly discontinuous between pronotum and elytron (Fig. 16A).

Coloration (Fig. 16A). Head and pronotum yellow-brown. Elytra fasciate, with longitudinal yellow maculae on red-brown background (Fig. 16A). Antennae and palpi yellow. Legs yellow brown. Ventral surfaces yello-brown, lighter on elytral epipleuron and apex of abdomen.

Sculpture and structure. Head moderately elongate, anterior clypeal margin broadly rounded; surface covered with few, sparse, fine punctures; eyes large. Pronotum subcordate, widest slightly anterior to middle; lateral bead fine; surface shiny with distinctive, moderately dense punctures. Elytra elongate, lateral margins subparallel in anterior 2/3 (Fig. 16A); lateral carina absent (Fig. 16B); surface similar to pronotum. Prosternum medially tectiform and setose; prosternal process elongate, slender, lateral margins subparallel, widest medially, longitudinally impressed, apex rounded (Fig. 16C). Metaventrite with anterior process short, slender, longitudinally impressed, apex narrowly rounded; metaventrite carina present mainly anteriorly along process, closely approximated, absent posteriorly (Fig. 16C); other surfaces sparsely punctate. Legs shiny, relatively impunctate; pro- and mesotibiae moderately broad; metatrochanter distinctly offset, apex rounded; metatibia with posteroapical brush of setae distinctive; metacoxa shiny and sparsely punctate; metacoxal lines broadly separated, anteriorly divergent (Fig. 16C). Abdomen shiny, sparsely punctate; ventrite VI apically somewhat narrowly rounded.

Male genitalia. Median lobe bilaterally slightly asymmetrical, in lateral aspect broadly curved, distinctly expanded in two places along ventral margin, submedially and subapically, apex narrowed to pointed apex (Fig. 16D); in ventral aspect narrow, lateral margins unevenly convergent to asymmetrical apex which is slightly curved to right (Fig. 16E). Lateral lobe moderately broad basally, elongate slender apically to rounded apex, with series of setae along apical margin (Fig. 16F).

Female genitalia. Not examined.

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

Variation. Very little variation was examined in the few specimens examined.

Etymology.

This species is named fasciatus, Latin for “striped,” for the fasciate color pattern on the elytra.

Distribution.

Hydrodessus fasciatus is known only from the type locality in Pará, Brazil (Fig. 45).

Habitat.

Nothing is known of the natural history of this species.

Specimens.

The holotype male is in FSCA labeled, "BRASIL:Para Rio Gurupi 12-15 km e. Caninde-Igarape Coraci xii.19.1965 #12 Borys Malkin/ Hydrodessus fasciatus Miller, 2016 [red label with black line border]."

Paratypes, 2 total. Brazil, Rio Gurupi 12-15 km E Caninde-Igarape Coraci, 19 Dec 1965, B. Malkin (2, FSCA).