Bolbocerogethes Audisio & Cline, 2009

Audisio, Paolo, Cline, Andrew Richard, Biase, Alessio De, Antonini, Gloria, Mancini, Emiliano, Trizzino, Marco, Costantini, Lorenzo, Strika, Sirio, Lamanna, Francesco & Cerretti, Pierfilippo, 2009, Preliminary re-examination of genus-level taxonomy of the pollen beetle subfamily Meligethinae (Coleoptera: Nitidulidae), Acta Entomologica Musei Nationalis Pragae 49 (2), pp. 341-504 : 385-387

12. Bolbocerogethes Audisio & Cline , gen. nov.

( Figs. 12 a–e )

Type species. Meligethes pallipes Boheman, 1851: 574 (by present designation) [= Bolbocerogethes pallipes ( Boheman, 1851) comb. nov.].

Generic description and diagnosis. The single known species (2.1–2.7 mm length; 1.5–1.9 mm width) exhibits the following combination of characters.

Body color and pubescence: pubescence silvery-whitish, short and fine, recumbent, not obscuring the reddish-brown dorsal body surface; pronotal and elytral sides narrowly flattened, typically the same color as disc. Lateral margin of pronotum and elytra with a series of faintly distinct, small and short setae, each seta usually 0.3–0.5× as long as those on elytral disc; posterior margin of pronotum with short, usually distally bifid or trifid microsetae, microsetae uniformly distributed on middle region anterior to scutellum.

Dorsal habitus: body markedly convex ( Fig. 12a ), peculiarly short and wide; dorsal punctures on discal portion of pronotum larger than eye facets, usually deeply impressed and densely distributed; anterior margin of clypeus subtruncate, not bordered ( Fig. 12a ), without medial bulge; circum-ocular furrows (occipital sulci) on dorsal side of head shallowly impressed, narrow, well-developed anteriorly only; eyes large and usually moderately projecting laterally ( Fig. 12a ); pronotum with distinct obtuse posterior angles, not directed posteriorly ( Fig. 12a ); scutellum regularly punctured on most of exposed portion; elytra with moderately coarse punctation, mostly organized with uneven transverse strigosity; elytral humeral angle scarcely distinct, not protruding laterally ( Fig. 12a ); elytral humeral striae indistinct; elytral pre-sutural striae faintly visible, originating slightly posteriorly the scutellar vertex, terminating close to elytral apex, and delimiting on each elytron an ill-defined, flat, sutural border, widest at posterior third, narrower than proximal portion of 3 rd antennomere; elytral apices truncately rounded in both sexes ( Fig. 12a ); pygidium partially exposed, moderately convex, apically rounded in both sexes ( Fig. 12a ).

Ventral habitus: antennal furrows markedly delimited, nearly parallel-sided, slightly diverging posteriorly; mentum subpentagonal, submental impression normally shaped; prosternal antennal furrows moderately raised and short on anterior margin; prosternal process peculiarly wide, subapical dilated portion 2.7–3.0× as wide as maximum width of 1 st antennomere, apex arcuately convex; lateral borders of prosternal process delimiting moderately shallowly impressed but distinct furrows, distally terminating over predistal lateral expansions, nearly reaching posterior margin; posterior margin of mesoventrite simple, not medially incised; male impressions on metaventrite moderately developed; first two visible abdominal ventrites simple in both sexes, without tufts of setae; caudal marginal lines of metacoxal cavities simple, moderately narrow, subparallel and contiguous to posterior margin of metacoxal cavities, comprising moderately deep arched impression of outer ‘axillary’ line; ‘axillary’ space on first abdominal ventrite moderately developed, ‘axillary’ angle widely obtuse; wide and short arched impressions on basal portion of last visible abdominal ventrite moderately impressed, partially covered by distal portion of penultimate visible abdominal ventrite.

Appendages: male 1 st antennomere 0.7–0.8× as long as width of protibiae excluding distal teeth ( Fig. 12a ); 3 rd antennomere in both sexes usually 1.9–2.0× as long as wide, 0.9–1.0× as long as but distinctly thinner than 2 nd antennomere ( Fig. 12a ); 4 th to 7 th antennomeres in both sexes subequal, short, slightly longer than wide, peculiarly subquadrate; antennal club compact, small, simple, comprising last 3 antennomeres in both sexes (8 th antennomere scarcely widened, 0.5–0.6× as wide as 9 th antennomere) ( Fig. 12a ), much narrower than width of protibiae, sexual dimorphism absent; labial palpi relatively short in both sexes, terminal segment nearly 1.8× as long as wide; maxillary palpi moderately short in both sexes, terminal segment only 1.8–1.9× as long as wide; mandible mid-sized ( Fig. 12a ), apex acuminate, no sexual dimorphism; tarsal claws moderately to strongly toothed at base; tarsi of normal size and shape, 0.5–0.7× as long as corresponding tibiae ( Fig. 12a ); protibiae with a series of relatively small, uneven teeth on distal third of lateral margin ( Fig. 12a ); meso- and metatibiae on lateral margin bearing a single and usually moderately even row of relatively long and fine pegs, without U-shaped sinuosity at distal third; meso- and metatibiae peculiarly short and wide ( Fig. 12a ), markedly and regularly arcuate along inner and outer margins; no sexual dimorphism in metatibial shape ( Fig. 12a ); tarsal plates of prolegs distinctly wider in males; posterior margin of metafemora in both sexes without gibbosities, spines, or tubercles.

Male genitalia: processes along inner side of parameres absent ( Figs. 12c–d ), tegmen comprising moderately deeply V-shaped excision on distal margin, without deep median longitudinal desclerotization from proximal portion of tegmen extending to medial distal V-shaped excision; median lobe of aedeagus short, peculiarly pyramidal distally, without lateral emargination.

Female genitalia (ovipositor): large; styli distinct, moderately long, unpigmented, simple, cylindrical, inserted away from apex of contiguous and moderately acuminate gonostyloids ( Fig. 12b ); each gonostyloid sclerotized but not darkly pigmented distally, with a simple, indentate outer portion of basicoxites, and a single, narrow, scarcely pigmented and sclerotized arcuate area along outer subdistal portion of gonostyloids. ‘Central point’ of ovipositor nearly centrally located, without proximad directed spicule.

Etymology. The generic name is derived from the subfamily Bolboceratinae ( Coleoptera , Geotrupidae ), to emphasize the peculiarly convex and short body shape and pale brown color of the type species ( Fig. 12a ) that strongly resembles members of this scarab subfamily, and from ‘- gethes ’, to emphasize its phylogenetic relationship with Meligethes . Gender masculine.

Biology. The biology of the single known species remains unknown. The few known specimens were collected by grassnetting in wet meadows, at low and middle altitudes (0–800 m) (S. Endrödy-Younga, pers. comm. 1995; R. Danielsson, pers. comm. 2000). K. Spornraft collected (19.xi.1988) a single specimen of B. pallipes in South Africa, Eastern Cape, Umtata, on a small plant of the legume family ( Fabaceae ) with pink flowers, but no definitive larval host-plant relationships can be postulated from this single isolated record (K. Spornraft, pers. comm. 1993).

Phylogenetic position. The relationships of Bolbocerogethes gen. nov. with other taxa of the ‘ Meligethes s. l. ’ group of genera remain obscure. The genus could be related to Afrogethes gen. nov. and allied taxa, but this hypothesis is only weakly supported by adult morphological characters. SPORNRAFT & KIREJTSHUK (1993) included this taxon in their ‘ Meligethes convexus -Gruppe’ (herein placed within Lamiogethes gen. nov.), but this placement was later reinterpreted as incorrect ( AUDISIO 1996). No molecular data are available for this isolated and peculiar genus.

Taxonomy and geographic distribution. Bolbocerogethes gen. nov. includes the single type species, which is apparently one of the rarest African Meligethinae species (but curiously among the first described African species of Meligethes ).

Bolbocerogethes pallipes ( Boheman, 1851) comb. nov. South Africa: eastern W Cape, E Cape, KwaZulu- Natal

Figures

Fig. 12. Bolbocerogethes Audisio & Cline, gen. nov.: a–e – B. pallipes (Boheman, 1851). a – male habitus (length 2.6 mm); b – ovipositor (modified from SPORNRAFT & KIREJTSHUK (1993); length 0.6 mm); c–d – male genitalia (c, d – length 0.3 mm); e – prosternal process (width 0.3 mm).