Bolboceras duplicatum, Krikken, Jan, 2013

Krikken, Jan, 2013, Distinguishing Bolboceras inaequale Westwood, 1848 and two new relatives from India (Coleoptera, Geotrupidae, Bolboceratinae), ZooKeys 276, pp. 55-66 : 61-62

Bolboceras duplicatum sp. n. Figures 5-611, 1520-21

Material examined.

Holotype male (RMNH) from South India: Madras [Chennai], x.1975, T.R.S. Nathan.

Diagnosis.

Saddle separating discomedian from discolateral concavities on pronotum short, thick, slightly lowered in relation to surrounding surface; discoparamedian tubercles approximated, but less than in the preceding species; discolateral concavity in no way extending onto anterolateral pronotal declivity. Interocular transverse ridge low, reaching paraocular ridge on either side, about halfway eye. Posterior edge of discomedian concavity only vaguely W-shaped. Pronotal tubercles with rounded tip. Anterolateral corners of clypeus appearing not strongly protuberant. Scutellum sparsely, finely punctate. Aedeagus unusual for Bolboceras : with blunt, membraneous parameres, the median apparatus lacking projecting sclerotized lateral stalks. Colour uniformly medium-brown. Body relatively large (length assumed roughly 10-11 mm).

Description

(holotype, male). Body length ca 11.5 mm. Colour uniformly medium-brown, shiny (surface locally worn, dull).

Labrum with vaguely emarginate anteromedian border, transverse ridge on coarsely punctate upper surface distinct. Clypeal surface with supra-anterolateral angles distinct, not raised (worn), intervening transverse anterior ridge very slightly convex in full-face view, almost straight; lateral perimarginal ridges distinct, moderately evenly curved, genal angle distinct. Clypeus densely, unevenly, distinctly punctate, frons abundantly, more finely punctate; secondary punctation on frons sparse. Anterior edge of eye canthus thickened-raised to slight arcuate-raised edge of short distal lobe; surface coarsely rugulate-punctate; paraocular ridge distinct, starting at genal angle, virtually straight, extending posteriorly along eye. Transverse interocular elevation situated halfway to eyes (in dorsal view), long, low, distinctly reaching paraocular ridges, its lateral slope slight, crest narrow, unmodified, lateral angle obsolete on either end (axial view).

Pronotum anteromedially steeply declivous, shortly depressed at base (lateral view), outline of marginate (raised) anterior border convex (dorsal view); discoparamedian and discolateral protrusions on pronotum distinctly protuberant, their tip rounded, particularly in discoparamedians (axial view); discomedian concavity very distinct, broad, largely situated behind closely set discoparamedian tubercles (not simply continuing over ante rior declivity), posterior edge slightly bisinuate (dorsal view); discolateral concavity deep, posterior edge rounded, anteriorly delimited by crowdedly, coarsely punctate patch behind eyes; saddle from discoparamedian tubercle to posterior disc broad, slightly lowered; bottom of discal concavities more or less matt; basomedian surface with sparsely punctate midline impression; anterolateral angle of marginal pronotal ridge ca 100˚ (full-face view). Pronotal surface with double punctation, primary punctation (size variable) laterally generally abundant; secondary punctation sparse, minute. Pronotal base broadly marginate, lined with row(s) of fine punctures. Scutellum with scattered, sparse double punctation.

Elytra with discal striae shallowly impressed, finely punctate; punctures separated by 3-5 puncture diameters, slightly crenulating interstriae (striae 2 and 5 slightly effaced in front). Elytral interstriae (on cross-section) very slightly convex, vaguely, sparsely, micropunctate.

Intercoxal anterior lobe of metasternum simply truncate in front.

Protibia with 6 external denticles (tips worn off); apex unmodified, with robust, complanate, slightly tapering spur. Outher side of meso- and metatibiae with bilobate apical and one complete anteapical fossorial elevation (their crest fringed with fine spines).

Aedeagus, Fig. 15; lateral stalks apparently absent, parameral sheaths membraneous, with blunt, folded tip.

Measurements of body parts. Median length of head (full-face, excluding labrum and mandibles) 2.5 mm, width 3.6 mm. Median length of pronotum (dorsal) 4.2 mm, maximum width 7.1 mm. Median length of scutellum 1.2 mm, maximum width 1.4 mm. Sutural length of elytra (dorsal) 4.1 mm, maximum width combined 7.2 mm. Width of genital capsule 1.20 mm.

Variation.

Only one male seen - beware of possibly deceptive polymorphism.

Distribution.

Southeast India.

Etymology.

Name refers to its similarity to the preceding species.