Megarthrus andinus, López-García, Margarita M., Méndez-Rojas, Diana M. & Navarrete-Heredia, José Luís, 2011

López-García, Margarita M., Méndez-Rojas, Diana M. & Navarrete-Heredia, José Luís, 2011, First record and a new species of Megarthrus Curtis (Coleoptera, Staphylinidae, Proteininae) from the Colombian Central Andes, Zootaxa 2916, pp. 62-64 : 62-64

Megarthrus andinus sp. nov.

Holotype. 3. COLOMBIA, Quindio Dept., Calarca, Planadas, 4°26’13.3” N 75°37’29” W, 3011 m, 14.v.2009 (Méndez- Rojas D. & López-García M.) ex leaf litter in cloud forest, CIUQ. Paratypes (5). Same data as holotype (1 3: ICN- MHN); same data as holotype, except for: 27.i.2011 (1 3, 1 Ƥ: CIUQ); same data as holotype, except for: 3.ii.2011 (1 3: IAvH, 1 Ƥ: CIUQ).

Description. Habitus as in Fig.1 . Combined length of pronotum and elytra= 1.4-1.6 mm; maximal pronotal width= 1 1.1 mm. Body dark brown with pronotum, antennae, legs, mentum and maxillary palpi somewhat paler; scape, pedicel and antennomeres 1, 2 and 11 paler than antennomeres 3 10. Dorsal pubescence fairly uniform, denser on pronotum than on elytron and abdomen; frontal setae directed forward, median area of frons less dense than on vertex; pronotum, elytra and abdomen with pubescence oriented posteriorly, elytral setae curved and recumbent, becoming denser near humeral area and with interspaces as wide as puncture diameters, abdominal pubescence becoming denser on lateral margins of tergites. Metasternal punctation deep with its median line almost impunctate.

Anterior margin of head non-truncate, nearly rounded. Temple rounded to subquadrate in dorsal view. Submentum surface weakly convex. Antenna filiform, 2.6 2.8 times longer than pronotum; with scape and pedicel sub-cylindrical and not flattened, segment 4 symmetrical and narrower than the remaining antennomeres which increase gradually in width, from segment 5 ( Fig. 2 ).

Pronotum 1.1 times longer than head; median portion convex with medial groove impunctate and flat. Pronotal disc shallowly depressed along basal and apical portion of lateral edge which is more deeply depressed medially. Hypomeron smooth with its inner edge wider in its median portion. Prosternal medial ridge absent; anterior prosternal margin bordered with a regular row of five longitudinal ridges. Protrochanter lacking transverse ridge. Scutellum with anterior border rounded and posterior border slightly acute, margins raised and with pubescence oriented posteriorly. Elytra 2.1 times longer than pronotum ( Fig. 1 ), weakly narrowed at base; humeral callus raised; disc with conspicuous swellings; anterior margin convex and inner apical angle obtuse. Abdominal sternites II and III with medial processes as in Fig. 3 . Hind wings fully developed.

Male: Frontoclypeal area not modified. Protarsamere 1 lacking adhesive setae. Mesofemur about as long as metafemur. Mesotibia shorter than metatibia. Metatarsomere 1 somewhat shorter than combined length of metatarsomeres 2 4. Peg-like setae arranged in a single row on mesotrochanter, mesotibia and metatibia. Sternite VIII as in Fig. 4 . Sternite IX lacking subbasal protuberance. Aedeagus as in Figs 5, 6 . Female: Abdominal tergite VIII lacking a medioapical projection. Sternite VIII as in Fig. 7 . Genital segment as in Figs 8 9 ; gonocoxal plate lacking a mediodorsal ridge.

Etymology. The specific epithet is an adjective referring to the Andean region.

Distribution. M. andinus is known only from its type locality, which is a patch of high Andean forest on the Central Cordillera of the Colombian Andes. The species appears to be restricted to a very specific and small area, because after sampling different forests by sifting leaf litter it was exclusively collected at this locality. This pattern is in accord with the narrowly endemic distributions recorded for other Neotropical Megarthrus species ( Cuccodoro 2011).

Remarks. From Neotropical Megarthrus species, M. mammiger Bierig 1940 from Costa Rica is the most similar to the Colombian new species, but the latter differs in the following characters: body smaller (3 3.4 mm instead of 3.8 mm); antennae longer, antennomeres 1, 2 and 11 paler, whereas in M. mammiger antennomeres 10 11 are paler; elytral and pronotal setae oriented posteriorly (fairly straight in M. mammiger ); male sternite VIII with apical margin rounded, bilobed, very wide and with medial emargination deep and U-shaped; aedeagus smaller and broader with parameres slightly shorter and with apex rounded.

Figures

FIGURES 1 – 9. Megarthrus andinus sp. nov. Habitus (scale bar = 1 mm) (1); antenna (2); medial process of abdominal sternites II and III, in lateral view (anterior to left) (3); male sternite VIII, dissected (4); ventral (5) and lateral (6) aedeagus; female sternite VIII (7); ventral (8) and lateral (9) female genital segment (scale bars = 0.2 mm).