Stilicoderus obesus, Rougemont, 2015

Rougemont, Guillaume De, 2015, Studies on Stiliderus Motschulsky and Stilicoderus Sharp: biogeographical notes and descriptions of new species (Coleoptera: Staphylinidae: Paederinae), Stuttgarter Beiträge zur Naturkunde A, Neue Serie 8, pp. 113-130 : 115

Stilicoderus obesus n. sp.

Holotype (♂): Irian Jaya, Jayawijaya Prov., Samboka, upper Kolff River , ca. 200 m, 10.–14.X.1996, sifted, leg. A. RIEDEL ( NHMW) .

Description

Body length 6 mm. Proportions of holotype: length of head: 85; breadth of head: 92; diameter of eye: 33; length of antenna: 187; length of pronotum: 84; breadth of pronotum: 79; length of elytron: 90; breadth of elytra: 95; metatibia: 84; metatarsus: 51.

Colour as in S. hieroglyphicus : pitchy black, elytra pitchy brown, antennae, palpi and legs dark reddish brown.

Male: apical margin of sternite VIII more deeply and less broadly excised than in related species. Aedoeagus see Fig. 4 , very large, over 1 mm long, the ventral blade constricted into a very slender apex concealed between the apices of the broad parameroid lobes.

Differential diagnosis

This new species belongs unequivocally in the hieroglyphicus group, yet is larger than any species of the group described hitherto, and is also distinctive by virtue of its elytral sculpture.

S. obesus n. sp. differs from S. hieroglyphicus Fauvel and other members of the group in several respects: greater size, head less transverse and narrower in propor- tion to pronotum and elytra, the minute, scarcely visible, lateral denticles of the labrum, and the elytral sculpture: the minute granules of the ground sculpture in this species have coalesced to form mostly longitudinal or diagonal vermiculate rugae; at low (×30–×40) magnification these rugae have the appearance of matted recumbent pubescence; the large foveate punctures of the elytra are obsolescent, obscured by the vermiculate/granulose puncturation. Two other, undescribed, species in NHMW respectively from Sorong Province and Fakfak Province are of comparable large size but differ in their more usual type of elytral sculpture.

Figures

Figs. 1–10X. Stilicoderus spp., aedoeagi in lateral (a) and ventral (b) views. – 1. S. laticeps n. sp. 2. S. riedeli n.sp. 3. S. cephalicus n.sp. 4. S. obesus n.sp. 5. S. kolaensis n. sp. 6. S. sepikensis n.sp. 7. S. riedelianus n.sp. 8. S. lobatus n.sp. 9. S. maritimoides n. sp. 10. S. meraukeanus n. sp. 10X. S. batantaensis n. sp. – Scales: 0.5 mm.