Fontidessus microphthalmus Miller & Montano

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 : 67-68

Taxon classification Animalia Coleoptera Dytiscidae

Fontidessus microphthalmus Miller & Montano sp. n. Figs 1, 10, 17, 24, 31, 34

Type locality.

Venezuela, Bolivar, Auyan–tepui, 5°51'N, 62°33'W.

Diagnosis.

Fontidessus microphthalmus is small (TL = 1.4-1.6 mm), but larger than all species except Fontidessus toboganensis , Fontidessus bettae , and Fontidessus aquarupe which are comparable in size (Figs 1-5). The dorsum is more pale in color than other species (darker along the elytral suture and lighter at the apex, but without distinctive maculae), and the eyes are relatively smaller than other species (Fig. 1, HW/EW = 1.4-1.5). The male genitalia are distinctive. The median lobe has two parts. The dorsal part is extremely broad, apically truncate and medially has a narrow emargination (Fig. 24A). The ventral part is elongate and apically pointed (Fig. 24A). The lateral lobes curve inward apically between the two parts of the median lobe (Fig. 24A).

Description.

Measurements. TL = 1.4-1.6 mm, GW = 0.8-0.9 mm, PW = 0.7-0.8 mm, HW = 0.5-0.6 mm, EW = 0.4 mm, TL/GW = 1.8, HW/EW = 1.4-1.5. Body (Fig. 1) broadly oval, dorsoventrally somewhat compressed; lateral outline nearly continuous between pronotum and elytron; lateral margins of pronotum gently curved; lateral margins of elytron evenly and gently curved.

Coloration. Head yellow brown, pronotum yellow, brown medially along posterior margin (Fig. 1); elytron yellow brown, apically lighter yellow brown. Ventral surfaces of thorax and abdomen 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 with distinct microreticulation; eyes small (Fig. 1, HW/EW = 1.4-1.5). Pronotal surface similar to that of head; with posterior angles obtuse; lateral bead narrow, of even width throughout, lateral margins weakly curved; pronotal striae finely incised, extending about 1/3 distance across pronotum (Fig. 1). Elytron with anterolateral angle obtuse, not extended anteriorly (Fig. 1); surface similar to pronotum, covered with fine microreticulation. Prosternal process narrow, lateral margins evenly curved and posteriorly convergent, apex of process narrowly rounded (Fig. 10); metacoxal process with lateral lobe minute. Pro- and mesotarsi relatively narrow in both male and female, but broader in male. Metatrochanter extremely large relative to metafemur (Fig. 17).

Male genitalia. Median lobe complex with two sections 1) an elongate ventral structure that is broad and evenly convergent to a narrowly rounded apex in dorsal aspect (Fig. 24A) and slender and evenly convergent to slight curved apex in lateral aspect (Fig. 24B), and 2) an elongate dorsal structure that is very broad, apically broadly truncate and medially narrowly emarginate in dorsal aspect (Fig. 24A) and slender in lateral aspect (Fig. 24B). Lateral lobes elongate, slender with apical segment medially curved between ventral and dorsal portions of median lobe (Fig. 24A).

Variation.

No significant variation was observed among the few specimens examined.

Etymology. The name of this species is derived from the Greek micro- meaning “small” and ophthalmos meaning “eye” for the relatively small eyes present in this species.

Distribution and habitat.

The species is known from two sites, one on the Auyan Tepui of the Gran Sabana of Venezuela, and the other on Kasikasima in the Sipilawini District of Suriname (Fig. 31) suggesting that the species may be characteristic of the Guyana Highlands. The specimens from Suriname are clearly hygropetric (Fig. 34), but the habitat is not known for the Venezuela specimens which were collected in an "intercept trap".

Comments.

This is a problematic species. It is, in many ways, like other species of Fontidessus , but the male median lobe is unusually modified and the "ventral sclerite" is either absent or the large ventral part (Fig. 24) is homologous with that structure in the other species. Also, the eyes are quite small (Fig. 1). In some ways, it approaches Spanglerodessus shorti Miller and García in being broad, but its shape and structure, with the median lobe divided into two portions and the dorsal portion apically emarginate, is much more like species of Fontidessus .

Material examined.

Holotype in MIZA: ♂ labeled, "VENEZUELA. Bolivar Auyan–tepui 1700m 5°51'N, 62°33'W 7 –14– 94 J.L. Garcia–A.Chacón / Trampa interceptacion ["intercept trap"]/ HOLOTYPE: Fontidessus microphthalmus Miller & Montano, 2014 [red label with black line border]". Paratypes: 4 labeled same as holotype except “… PARATYPE: Fontidessus microphthalmus Miller & Montano, 2014 [blue label with black line border]"; 9 labeled "SURINAME: Sipaliwini District 2°58.555'N, 55°24.739'W 515 m Camp 4 (summit), Kasikasima leg. A. Short; small seepage on top of METS trail; 24.iii.2012 2012 CI–RAP Survey SR12 –0324– 01A/ PARATYPE: Fontidessus microphthalmus Miller & Montano, 2014 [blue label with black line border]".