Oosternum cercyonoides, Deler-Hernández & Cala-Riquelme & Fikáček, 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 5-6 21 31 41 50 61

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.

Figures

Figure 61. Distribution of the representatives of the Oosternum from West Indies. Shape of the symbols indicate the species group which the respective species belongs to (see the Discussion for details).

Figures 1 - 12. Habitus of Oosternum from West Indies. 1 - 2. Oosternum andersoni sp. n., lenght = 1.25 mm (1. dorsal view, 2. lateral view). 3 - 4. Oosternum bacharenge sp. n., lenght = 1.40 mm (3. dorsal view, 4. lateral view). 5 - 6. Oosternum cercyonoides sp. n., lenght = 1.95 mm (5. dorsal view, 6. lateral view). 7 - 8. Oosternum insulare sp. n., lenght = 1.40 mm (7. dorsal view, 8. lateral view). 9 - 10. Oosternum latum Fikacek, Hebauer & Hansen, 2009, lenght = 1.50 mm (9. dorsal view, 10. lateral view). 11 - 12. Oosternum luciae sp. n., lenght = 1.41 mm (11. dorsal view, 22. lateral view).

Figures 19 - 28. Pronotal punctation and microsculpture. 19. Oosternum andersoni 20. Oosternum bacharenge 21. Oosternum cercyonoides 22. Oosternum insulare 23. Oosternum latum 24. Oosternum luciae 25. Oosternum megnai 26. Oosternum pecki 27. Oosternum sharpi 28. Oosternum sp. (Bahamas).

Figures 29 - 38. Median portion of prosternum. 29. Oosternum andersoni 30. Oosternum bacharenge 31. Oosternum cercyonoides 32. Oosternum megnai 33. Oosternum pecki 34. Oosternum sp. (Bahamas) 35. Oosternum insulare 36. Oosternum latum 37. Oosternum luciae 38. Oosternum sharpi.

Figures 39 - 44. Meso- and metaventrite plate. 39. Oosternum andersoni 40. Oosternum bacharenge 41. Oosternum cercyonoides 42. Oosternum insulare 43. Oosternum latum 44. Oosternum luciae.

Figures 49 - 52. Additional diagnostic characters of West Indian Oosterum. (49) Pronotal punctation of Oosternum pecki. (50 - 52) Apical portion of elytra 50. Oosternum cercyonoides 51. Oosternum megnai 49, 52. Oosternum pecki.