Megarthrus rufomarginatus Cameron

Cuccodoro, Giulio & Liu, Zhiping, 2016, Megarthrus of southern India and Sri Lanka, with notes on their phylogenetic and biogeographical relationships (Coleoptera: Staphylinidae: Proteininae), Zootaxa 4097 (4), pp. 530-544 : 541-543

Megarthrus rufomarginatus Cameron

( figs 66–74 )

Megarthrus rufomarginatus Cameron : 1913, 525; Cuccodoro 2003, 388, figs 35–36 (redescription). Type locality: Nilgiri Hills. Lectotype male (BMNH).

Specimens examined. 49: INDIA: Tamil Nadu: "H. L. Andrewes, Nilgiri Hills | M. rufomarginatus Cam. [manuscript] | Type " (lectotype male, BMNH); "Nilgiris, S India [manuscript]" (paralectotypes: BMNH, 5 females; DEI, 1 female; FMNH, 2 female); Anaimalai Hills, 10 km N Valparai, 1250m, 18.xi.1972, leg. Besuchet, Löbl & Mussard #35 [sifting in forest] (MHNG, 1 male and 1 female); same data, but Valparai, 1100m, 20.xi.1972 [sifting in forest with coffee trees] (BMNH, 2 males and 1 female; MHNG, 2 males and 1 female); Kerala: Cardamom Hills, 5 km SW Kumily, 1000m, 6.xi.1972, leg. Besuchet, Löbl & Mussard #11 [sifting forest leaf litter] (BMNH, 1 female); Cardamom Hills, 10 km SW Kumily, Vallakadavu, 77°07’E 09°31’N, 1000m, 24.xii.1993, leg. Boukal & Kejval (MHNG, 1 male and 1 female; NHMW, 2 males and 2 females); Cardamom Hills, Pambanar— Peermade, 950m, 9.xi.1972, leg. Besuchet, Löbl & Mussard #18 [sifting in forest, near river] (BMNH, 2 males and 1 female; MHNG, 3 males and 2 females); Nelliampathi Hills, Kaikatty, 900m, 30.xi.1972, leg. Besuchet, Löbl & Mussard, #58 [sifting forest leaf litter, near stream] (BMNH, 2 males; MHNG, 6 males and 6 females); Thekkady, Peryar W.L.S., 2.ix.1989, leg. Riedel (MHNG, 1 female; SMNS, 1 male and 1 female).

Diagnosis. Body (fig. 2) predominantly chestnut brown, with lateral pronotal margins, legs and antennae slightly paler, the latter unicolored; combined length of head, pronotum and elytra = 1.40–1.65 mm; maximal pronotal width = 0.80–0.95 mm; occipital ridge well marked, with anterolateral portions sinuate, extended from lower eye margins dorsally to nearly third of neck width, then sharply recurved posterolaterally back to upper level of eyes, posterolateral portions connected dorsally with irregular transverse ridge; antennae with short and dense pubescence present only on antennomeres 8–11; antennomeres 9–10 strongly asymmetrical similar to that in fig. 63.

Male: frontal margin unmodified; protarsomeres 1 without tenent setae; protarsomeres 5 with adventral projecting flat apophysis; metatibiae markedly curved, apical half with adventral row of peg-like setae; mesotrochanters with two rows of peg-like setae; abdominal sternites IV and V each with medial area swollen and bearing short transverse ridge, swollen area on sternite IV higher than that on sternite V; abdominal sternite VIII with well delimited discoidal hyaline medial impression; aedeagus as in figs 66–69.

Female. Tergite VIII as in figs 73–74; valvifers fused dorsally on entire length (figs 71–72); dorsal part of genital segment as in fig. 70.

Comparisons and diagnostic notes. The sexual dimorphism of sternites IV and V has been overlooked by Cuccodoro (2003). See comparisons and diagnostic notes under M. bimaculatus and M. lanka sp. nov.

Distribution and Natural History. The species has been collected so far only in Tamil Nadu (Nilgiri and Anaimalai Hills) and Kerala (Cardamom and Nelliampathi Hills), where it was found in forest leaf litter at elevations ranging from 900 to 1100 m.a.s.l.

The specimens recorded by Cameron (1928) from « Fort de Kock, Sumatra » belong to a different, still unnamed species ( Cuccodoro 2003).

Figures

FIGURES 66 – 74. Megarthrus rufomarginatus Cameron; male, aedeagus in ventral (66, 69) and lateral (67, 68) views; female genital segment, ventral part in dorsal (71) and lateral (72) views, and dorsal part (70) in ventral view; female abdominal tergite 8 in dorsal (73) and lateral (74) views. Scale bar = 0.1 mm.