Oosternum megnai, 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 megnai sp. n. Figs 13-14 25 32 45 51 58 61

Type-locality.

Cuba, Granma Province: PN Turquino, 20°0.9'N, 76°53.3'W, slope below Pico Naranjo ca. 0.4 km N of La Platica (by air), 950 m.

Type-specimens

(13 spec.). Holotype male, dry mounted, with genitalia mounted in Euparal on a microslide attach to the specimens. Original label: "CUBA: Granma: PN Turquino, slope below Pico Naranjo ca. 04 km N of La Platica (by air), 24.vi.2012, Deler-Hernández & Fikáček leg. 20°0.9'N, 76°53.3'W, elevation 950 m, MF23 [printed] / Holotype, Oosternum megnai sp. n., Deler-Hernández & Fikáček det. 2013 [red, printed]" (NMPC). Paratypes CUBA: Granma province: same data as holotype (12 spec., NMPC, CMN, SEMC, BSC-E, BMNH).

Diagnosis.

Body widest ca at midlength. Lateral margin of pronotum angulate. 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 rounded. Elytral interval 2 narrower than 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 narrow, drop-like, 2.3 × longer than wide. Interstices of median part of metaventrite without microsculpture. Anterolateral ridges of metaventrite not meeting together mesally. Parameres 0.8 × longer than phallobase, bearing two long setae apically. Median lobe longer than parameres, oval in shape, with small apical projection. Membranous lateral projections of median lobe absent.

Description.

Habitus. Body elongate oval, gradually narrowing posteriad; total length/total width ratio = 1.9. Length: 1.47-1.49 mm, length of holotype: 1.32 mm; width: 0.75-0.82 mm, width of holotype: 0.8 mm.

Coloration. Coloration of dorsal side brown to dark brown, head, pronotum and elytra dark brown. Ventral side light brown. Femora, tibiae, tarsi and antennomeres and light brown, antennal club dark brown.

Head. Clypeus with moderately dense punctation consisting of fine punctures, each puncture bearing fine decumbent seta; setae pale; interstices without microsculpture; anterior margin of clypeus truncate. Frons with dense punctation consisting of small, punctures of same shape medially and laterally; interstices without microsculpture. Eyes moderately large. Mentum 1.8 × wider than long, anterior margin deeply emarginate; anteromedian part not distinctly impressed; with sparse punctation, punctation consisting of minute, nearly indistinct punctures bearing minute setae; interstices with fine microsculpture consisting of transverse ridges. 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 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, slightly sparser laterally than medially; all punctures bearing long setae; interstices without microsculpture. Median portion of prosternum not elevated and demarcated from lateral portions, median carina of prosternum narrow, projecting more anteriad mesally than anterior margin of median portion, with anterior portion elevated into small tooth in lateral view. Postero-mesal projection with shallow notch. Antennal grooves moderately large. Lateral margin of antennal grooves rounded.

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). Elytral interval 2 narrower than 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 narrow, drop-like, 2.3 × 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 without microsculpture.

Metathorax. Metaventrite distinctly longer than preepisternal elevation of mesothorax, median portion markedly differing from lateral portion in punctation and microsculpture; punctation of median portion sparse consisting of small rounded 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.

Male genitalia. Aedeagus 0.52 mm long, parameres 0.8 × longer than phallobase. Parameres continuously narrowing apicad, bearing two long setae apically. Phallobase narrow, 2.1 × longer than wide. Median lobe longer than parameres, oval in shape, with small apical projection. Membranous lateral projections of median lobe absent. Gonopore absent.

Etymology.

The new species is dedicated to our excellent colleague and friend Yoandri S. Megna (Universidad de Oriente, Santiago de Cuba, Cuba).

Distribution.

Oosternum megnai sp. n. is the Cuban endemic species currently known only from the type locality in the southeastern part of the island (Granma province) ( Fig. 61 ). The locality is situated in the Sierra Maestra mountain range which is considered one of the main centers of diversity in Cuba ( CENAP 2004).

Habitat.

Specimens of Oosternum megnai were collected in dry leaf litter in the secondary 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 13 - 18. Habitus of Oosternum from West Indies. 13 - 14. Oosternum megnai sp. n., lenght = 1.49 mm (13. dorsal view, 14. lateral view). 15 - 16. Oosternum pecki sp. n., lenght = 1.50 mm (15. dorsal view, 16. lateral view). 17 - 18. Oosternum sharpi Hansen, 1999, length = 1.37 mm (17. dorsal view, 18. 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 45 - 48. Meso- and metaventrite plate. 45. Oosternum megnai 46. Oosternum pecki 47. Oosternum sharpi 48. Oosternum sp.

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.

Figures 53 - 60. Aedeagus. 53. Oosternum andersoni 54. Oosternum bacharenge 55. Oosternum insulare 56. Oosternum latum 57. Oosternum luciae 58. Oosternum megna i 59. Oosternum pecki 60. Oosternum sharpi.