Oosternum cercyonoides, Deler-Hernandez, Albert, Cala-Riquelme, Franklyn & Fikacek, Martin, 2014

Deler-Hernandez, Albert, Cala-Riquelme, Franklyn & Fikacek, Martin, 2014, A review of the genus Oosternum Sharp of the West Indies (Coleoptera: Hydrophilidae: Sphaeridiinae), Deutsche Entomologische Zeitschrift 61 (1), pp. 43-63 : 43

Oosternum cercyonoides sp. n. Figs 5-62131415061

Type-locality.

Jamaica, St. Thomas P. Portland Gap: 18°1 ’44.76” N, 76°30 ’22.40” W, 1676 m.

Type-specimens

(5 spec.). Holotype female. Original label: "JAMAICA: St. Thomas P. Portland Gap, 17.xii.1972/01.i.1973, S & J. Peck, elevation 5500ʹ, cloud for., dung & carrion tr. [printed] / Holotype, Oosternum cercyonoides sp. n., Deler-Hernández & Fikáček det. 2013 [red, printed]" (CNC). Paratypes: JAMAICA: St. Thomas P. Portland Gap: same data as holotype (4 spec., CNC, BSC-E, NMPC).

Diagnosis.

Body widest ca at midlength. Lateral margin of pronotum angulate. Pronotal punctation uniform in size, moderately dense consisting of small rasp-like punctures. Pronotal interstices without microsculpture. Mesal part of prosternum not divided from lateral portions. Lateral margin of antennal grooves subangulate. Elytral interval 2 of the same width as interval 3, as high as intervals 1 and 3, reaching elytral apex. Elytral intervals 5, 7 and 9 as convex as adjacent intervals. Elytral interstices shiny, without microsculpture. Preepisternal plate wide, drop-like, 1.7 × longer than wide. Interstices without microsculpture, shiny. Anterolateral ridges of metaventrite not meeting together of median part of metaventrite mesally.

Description.

Habitus. Body elongate oval, gradually narrowing posteriad; total length /total width ratio = 2.5. Length: 1.9-1.95 mm, length of holotype: 1.9 mm; width: 0.75-0.78 mm, width of holotype: 0.78 mm.

Coloration. Coloration of dorsal side brown to dark brown, elytra darker than pronotum, head dark brown. Ventral side brown. Femora and tibiae brown, tarsi and mouthparts yellow.

Head. Clypeus with sparse punctation consisting of small rounded punctures, each puncture bearing fine decumbent seta; setae pale; interstices without microsculpture; anterior margin of clypeus truncate. Frons with dense punctation consisting of coarse, impressed rounded punctures, punctures of same shape medially and laterally; interstices without microsculpture. Eyes moderately large. Mentum 1.8 × wider than long, anterior margin slightly emarginate; anteromedian part not distinctly impressed; with sparse punctation, consisting of small, nearly indistinct punctures bearing minute setae; interstices with very fine microsculpture, opaque. Submentum without poriferous disc-like fields. Maxillary palpus with palpomeres 2 and 4 ca. 1.2 × longer than palpomere 3.

Prothorax. Pronotum evenly convex forming continuous curve with elytra in lateral view. Lateral margin of pronotum angulate, with narrow marginal bead. Pronotal punctation uniform in size, moderately dense, as dense as that on frons, consisting of small rasp-like punctures similar on whole surface of pronotum; all punctures bearing long setae; interstices without microsculpture. Median portion of prosternum not elevated and demarcated from lateral portions, median carina of prosternum narrow, not projecting more anteriad mesally than anterior margin of median portion, with anterior portion elevated into small tooth in lateral view. Postero-mesal projection with deep notch. Antennal grooves moderately large. Lateral margin of antennal grooves subangulate.

Mesothorax. Scutellar shield bearing a few small rasp-like punctures; interstices without microsculpture. Elytral series 1-5 and 8 arising basally, series 6-7 and 9 joint subbasally. Serial punctures small; transverse; sparsely arranged; with minute setae (indistinct under binocular microscope). Interval 2 of the same width as interval 3, as high as intervals 1 and 3, reaching elytral apex, intervals 5, 7 and 9 as convex as adjacent intervals. Elytral interstices shiny, without microsculpture. Preepisternal plate wide, drop-like, 1.7 × longer than wide, widely attached to metaventrite; posterior part of preepisternal elevation slightly overlapping over anterior margin of metaventrite; median part flat; bearing sparsely arranged shallow setiferous punctures; interstices without microsculpture.

Metathorax. Metaventrite distinctly shorter than preepisternal elevation of mesothorax, median portion markedly differing from lateral portion in punctation and microsculpture; punctation of median portion consting of sparsely arranged but large rasp-like setiferious punctures, interstices without microsculpture, shiny. Anterolateral ridges bent posteriad along lateral margin of metaventrite, concave laterally, not meeting together mesally. Anterior margin of metaventrite not crenulate.

Abdomen. Ventrite 1 with additional longitudinal ridges laterally. Ventrites 2-5 without longitudinal ridges; posterior margin of all ventrites lacking denticles.

Etymology.

The species name is derived from the name of the megasternine genus Cercyon Leach, 1817 , reflecting the Cercyon -like appearance of this new species.

Distribution.

Oosternum cercyonoides sp. n. is a Jamaican endemic currently only known from the type locality in the Blue Mountains, i.e. the highest mountain massif in the eastern part of the island (Fig. 61).

Habitat.

Based on the label data, the specimens were collected using baited pitfall traps in the montane cloud forest.