Oosternum insulare, 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 insulare sp. n. Figs 7-82235425561

Type-locality.

Jamaica: Cockpit Country, 18°20 ’51.7” N, 77°38 ’29.7” W, 250 m, trail to upper Windsor Cave.

Type-specimens

(10 spec.). Holotype male, dry mounted, with genitalia mounted in Euparal on a microslide pinned below the specimen. Original label: "JAMAICA, Cockpit Country, trail to upper Windsor Cave, 11.xi.2013, ca. 250 m a.s.l., 18°20 ’51,7” N, 77°38 ’29,7” W, F. Cala-Riquelme leg. [printed] / Holotype, Oosternum insulare sp. n., Deler-Hernández & Fikáček det. 2013 [red, printed]' (NMPC). Paratypes: JAMAICA: Cockpit Country: same data as holotype (5 spec., NMPC, CMN, SEMC, BMNH). Trelawny, 5 mi. N. Alberttown, 30.xii.1972, S&J. Peck leg. Ber. 250 (3 spec., CNC). Portland: 1 mi W Ecclesdown, 18°5 ’33.08” N, 76°30 ’3.64” W, 10.viii.1974, S & J. Peck leg., 1500ʹ (1 spec., CNC).

Diagnosis.

Body widest ca at midlength. Lateral margin of pronotum angulate. Pronotal punctation uniform in size, dense, consisting of large rounded punctures. Pronotal interstices without microsculpture. Mesal part of prosternum divided from lateral portions by oblique sharp ridges. Lateral margin of antennal grooves with acute projection. Elytral interval 2 narrower than interval 3, lower than intervals 1 and 3, reaching elytral apex. Elytral intervals 5, 7 and 9 distinctly higher than adjacent intervals. Elytral interstices shiny, without microsculpture. Preepisternal plate wide, drop-like, 1.8 × longer than wide. Median elevate portion of metaventrite nearly reaching lateral margins, interstices of median part of metaventrite with very fine microsculpture, opaque. Anterolateral ridges of metaventrite not meeting together mesally. Parameres 0.7 × longer than phallobase, bearing a single seta apically. Median lobe ca. 1.5 × longer than parameres, slight narrowing from base towards apex, with minute apical projection. Membranous lateral projections of median lobe absent.

Description.

Habitus. Body elongate oval, gradually narrowing posteriad; total length /total width = 1.6. Length: 1.3-1.4 mm, length of holotype: 1.4 mm; width: 0.78-0.84 mm, width of holotype: 0.84 mm.

Coloration. Coloration of dorsal side reddish brown. Ventral side dark to reddish brown. Femora and tibiae dark brown, tarsi, mouthparts and antennomeres 1-6 yellowish.

Head. Clypeus with sparse punctation consisting of fine puncture, each puncture bearing fine decumbent seta; setae pale; interstices without microsculpture; anterior margin of clypeus slightly concave. Frons with dense punctation consisting of coarse rounded punctures, punctures of same shape medially and laterally; interstices without microsculpture. Eyes moderately large. Mentum 1.9 × wider than long, anterior margin slightly emarginate; anteromedian part deeply impressed in contrast to lateral portions; with sparse punctation, 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. Antenna with 9 antennomeres; scapus shorter than antennomeres 2-6 combined.

Prothorax. Pronotum evenly convex, slightly more convex than elytra in lateral view; lateral margin angulate, with narrow marginal bead. Pronotal punctation consisting of two types of punctures, large rounded without seta and smaller transverse with long seta; interstices without microsculpture. Transverse row of punctures on posterior margin of pronotum hardly defined. Median portion of prosternum elevated and demarcated from lateral portion. Median carina of prosternum narrow, projecting more anteriad mesally than anterior margin of median portion, straight in lateral view. Median portion of prosternum 1.2 × wider than long, postero-mesal projection with shallow notch. Pair of deep pits next to ridge delimiting median portion of prosternum present. Antennal grooves moderately large. Lateral margin of antennal grooves with acute projection.

Mesothorax. Scutellar shield bearing a few small, round punctures; interstices without microsculpture. Elytral series 1-6 arising basally, series 7-9 subbasally. Serial punctures small; transverse; sparsely arranged, with minute setae (indistinct under binocular microscope). Interval 2 narrower than interval 3, lower than intervals 1 and 3, reaching elytral apex, intervals 5, 7 and 9 distinctly higher than adjacent intervals. Elytral interstices shiny, without microsculpture. Preepisternal plate wide, drop-like, 1.8 × longer than wide, widely attached to metaventrite; posterior part of preepisternal elevation slightly overlapping over anterior margin of metaventrite; median part flat, bearing densely arranged, large, shallow setiferous punctures; interstices with very fine microsculpture, opaque.

Metathorax. Metaventrite ca. as long as preepisternal elevation of mesothorax, median portion markedly differing from lateral portion in punctation and microsculpture reaching nearly to lateral margin; punctation of median portion sparse consisting of small, rounded punctures, interstices without microsculpture, shiny. Anterolateral ridges bent posteriad along lateral margin of metaventrite, angulate laterally, not meeting together mesally. Anterior margin of metaventrite crenulate.

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

Male genitalia. Aedeagus 0.57 mm long, parameres 0.7 × longer than phallobase. Parameres continuously narrowing apicad, bearing a single seta apically. Phallobase narrow, 3 × longer than wide. Median lobe ca. 1.5 × longer than parameres, slight narrowing from base towards apex, with minute apical projection. Membranous lateral projections of median lobe absent. Gonopore absent.

Etymology.

The species name is the manuscript name used in an unpublished revision of the genus Oosternum by M. Hansen - it was the only West Indian endemic in the manuscript, hence the highlighting of the fact that it is the island endemic.

Distribution.

Oosternum insulare sp. n. is the Jamaican endemic currently known from three localities throughout the island, all situated in the altitudes around 500 m a.s.l. (Fig. 61).

Habitat.

Specimens of Oosternum insulare were collected from leaf litter of the well-preserved semi-deciduous forest in the karst area.