Fontidessus wheeleri Miller, 2008

Miller, Kelly B. & Montano, Elizabeth T., 2014, Review of the genus Fontidessus Miller & Spangler, 2008 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini) with description of four new species, ZooKeys 426, pp. 65-85 : 77-78

Taxon classification Animalia Coleoptera Dytiscidae

Fontidessus wheeleri Miller, 2008 Figs 9, 16, 23, 30, 31

Fontidessus wheeleri Miller, 2008 in Miller and Spangler 2008: 50.

Type locality.

Venezuela, Territorio Federal Amazonas, 40km S Puerto Ayacucho, at El Tobogan, Coromoto.

Diagnosis.

Fontidessus wheeleri are small (Fig. 9, TL = 1.2-1.3 mm). Specimens are marked on the elytra with transverse and longitudinal yellow maculae that are distinctly demarcated. The male median lobe terminates in two, short, slender rami with small, subapical, lateral, hyaline lobes (Fig. 30).

Redescription.

Measurements. TL = 1.2-1.3 mm, GW = 0.6-0.7 mm, PW = 0.5-0.6 mm, HW = 0.4-0.5 mm, EW = 0.2-0.3 mm, TL/GW = 1.7-1.8, HW/EW = 1.6-1.7. Body (Fig. 9) oval, elongate; lateral outline slightly continuous between pronotum and elytron; lateral margins of pronotum gently curved; lateral margins of elytron evenly and gently curved.

Coloration. Head yellow brown, brown along posterior margins and medial margins of eyes; pronotum broadly brown along posterior margin, narrowly dark brown along anterior margin; elytron brown with the following yellow maculae: 1) a basal macula in an irregular band extending posteriorly along suture at medial margin, 2) a lateral longitudinal macula posterior to humeral angle, broader anteriorly and extending posteriorly in narrow band to near apex, 3) a subtriangular subapical macula (Fig. 9). Ventral surfaces of thorax and abdomen dark brown except prosternum, prosternal process, propleuron and pronotal epipleuron yellow-brown; appendages yellow to yellow-brown.

Sculpture and structure. Head with very fine, inconspicuous, irregular punctation, surface between punctures shiny, without distinct microsculpture; eyes medium in size (Fig. 9, HW/EW = 1.6-1.7). Pronotal surface similar to that of head, with posterior surface with fine microsculpture; with posterior angles obtuse; lateral bead slender, of even width throughout; pronotal striae finely incised, extending nearly 1/2 distance across pronotum (Fig. 9). Elytron with anterolateral angle obtuse, not extended anteriorly (Fig. 9); surface similar to pronotum, with microsculpture indistinct. Prosternal process elongate and slender, lateral margins slightly concave, apex of process rounded (Fig. 16); metacoxal process with lateral lobe small. Pro- and mesotarsi relatively narrow in both male and female, but slightly broader in male. Metatrochanter very large relative to metafemur (Fig. 23).

Male genitalia. Median lobe in ventral aspect broad, tapering slightly, apically bifid and slender, deeply and narrowly emarginate medially, with short, hyaline, sub-triangular lobes subapically on each side (Fig. 30A); in lateral aspect moderately broad, curved, with apical portion evenly tapered to pointed apex (Fig. 30C). Lateral lobe elongate, expanded apically, broadly rounded at apex, with series of long setae along dorsal margin (Fig. 30B).

Variation.

The extent of the dorsal maculae varies among specimens with some having the maculae reduced, but most with extensive maculae that are well-defined.

Distribution and habitat.

This species is known only from a few localities along the far western margin of the Guiana Shield around Puerto Ayacucho (Fig. 31). Specimens have been found in hygropetric situations.

Comments.

This species was originally based on two specimens (the holotype and a paratype) that were originally collected together with the type series of Fontidessus ornatus and Fontidessus toboganensis , which were described at the same time ( Miller and Spangler 2008). The holotype of Fontidessus wheeleri had been dissected some time prior to the original description, but, based on a few additional specimens examined for this paper, the male genitalia were apparently somewhat damaged (torn and crushed somewhat), and also switched with those of the holotype of Fontidessus ornatus , which had also been dissected previously. For that reason, the male genitalia are redescribed and reillustrated here based on newly dissected specimens in association with the correct species based on examination on a few additional specimens. This species has been only rarely collected.

Material examined.

Six total specimens from the following localities: VENEZUELA: Amazonas: 40km S Puerto Ayacucho, El Tobogan, Caño Coromoto 5.38678°N, 67.61537°W; ca 15km S Puerto Ayacucho, 5.51038°N, 67.60181°W; Bolivar: ca 25km E El Burro, 6.21794°N, 67.24066°W.