Sacosternum

Fikáček, Martin & Short, Andrew E. Z., 2010, A revision of the Neotropical genus Sacosternum Hansen (Hydrophilidae: Sphaeridiinae: Megasternini), Zootaxa 2538, pp. 1-37 : 28-29

Sacosternum sp. B

(Figs. 1–2, 40, 45, 49, 53)

Material examined. COSTA RICA: 1 female ( KSEM): “ COSTA RICA: Cartago Province / Tapanti Nat. Prk; 1200m elv. / HG-vapor light @visitor cabinas / 11.i.2005; AS-05-148 / A. Short, J. Hannam, A. Swanson”.

Differential diagnosis. Body highly convex in lateral view; head evenly convex, without depressions between eyes; eyes large, separated by 2.1× of width of one eye; a tuft of yellowish erect setae anteriorly of each eye absent; pronotum evenly convex, without sublateral impressions, forming continuous curve with elytra in lateral view; lateral margin of pronotum weakly sinuate; pronotal interstices without microsculpture; median portion of prosternum 1.9× wider than long; lateral expansions of prosternal shield developed; punctures of elytral series small, transverse, slightly larger than interval punctures; preepisternal plate 1.2× longer than wide, triangular, without median longitudinal carina, widely attached to metaventrite, its median part flat; metaventrite distinctly longer than preepisternal elevation of mesothorax; anterolateral ridge subparallel to posterior margin of mesocoxal cavity laterally; median carina of metaventrite reaching posterior fifth of length in female; femoral lines and triangular area at sides of metaventrite absent; protibiae not emarginate on outer margin apically; ventrite 1 with weak longitudinal ridges; ventrites 2–5 without longitudinal ridges; abdominal ventrite 5 entire in female. Body length 1.6 mm.

Easily recognizable from remaining Sacosternum species except from Sacosternum sp. A by the shape of the anterolateral ridge, highly convex body in lateral view, triangular preepisternal elevation of mesothorax and absence of longitudinal ridges on abdominal ventrites 2–5. The species can be distinguished from Sacosternum sp. A by the characters provided in the key.

Biology. Unknown. The only known specimen was collected at light.

Distribution. Known only from the above locality in Costa Rica.