Chapischema, Caterino, Michael S. & Tishechkin, Alexey K., 2014

Caterino, Michael S. & Tishechkin, Alexey K., 2014, New genera and species of Neotropical Exosternini (Coleoptera, Histeridae), ZooKeys 381, pp. 11-78 : 31-32

Chapischema gen. n.

Type species.

Chapischema doppelganger sp. n.

Description.

This genus differs from other Exosternini in the following combination of characters: body elongate, cylindrical, parallel-sided, glabrous; frons subangulate in front of eyes, moderately produced above antennal insertions, weakly depressed at middle; epistoma convex, apex truncate; labrum about twice as wide as long; left mandible with outwardly arcuate incisor edge, right mandible with small acute basal tooth; submentum slightly depressed, outwardly arcuate along anterior margin; mentum subtrapezoidal, very narrowly emarginate apically, sparsely setose; cardo glabrous, smooth; stipes with few long setae; all palpi relatively stout, ultimate palpomeres, particularly maxillary palps, thickened and with numerous conspicuous punctures; antennal scape elongate, sides sinuate, narrowed at middle in anterior aspect; funicle gradually but slightly widened to apex, 8th antennomere as long as preceding antennomeres; antennal club small, about as long as preceding 4 antennomeres, lacking complete annuli, sensoria poorly defined, apparently with two widely interrupted annuli close to dorsal apex; pronotal disk with only single distinct pair of gland openings, present between anterior margin and anterior submarginal stria; prescutellar impression absent; prosternal keel very shallowly emarginate at base; prosternal lobe slightly deflexed; anterior margin of mesoventrite broadly emarginate, but very weakly produced at center; propygidium rather long, more or less flat, with small gland openings near anterolateral corners; pygidium slightly longer than propygidium along midline, apical margin simple, rounded; protrochanter glabrous, meso- and metatrochanters each with two very short apical setae; femora simple; protibia with outer margin rounded, weakly dentate, strongly spinose; protibial spurs very short; protarsus with ventral setae simple; meso- and metatibiae elongate, outer margins with spinose, mesotibia faintly dentate; meso- and metatarsi short, each with single pair apicoventral spines; male genitalia with accessory sclerites present; T8 rather short; S8 halves approximate only at base, inner margins divergent to apex, apically with very fine, inconspicuous setae; T9 with prominent, strongly hooked ventrolateral apodemes, dorsal lobes more strongly sclerotized along sides; T10 divided; S9 with apical emargination distinct, apical flange interrupted; tegmen with very large medioventral process; median lobe simple; female not known.

Remarks.

In body form Chapischema is generally very similar to the preceding new genus, Pyxister (and likewise to Megalocraerus , and various other rare cylindrical Neotropical Exosternini ). Among such taxa, it can best be recognized by its carinate frontal stria (Fig. 11C), abbreviated epipleural stria, and mesoventral margin, which is simultaneously broadly emarginate and narrowly produced at the middle (Fig. 11B). Generic status is supported principally by its unique male genitalia, with a very prominent medioventral tooth on the tegmen (Fig. 12F). It is resolved as closely related to Scaptorus and Enkyosoma in our forthcoming analysis of Exosternini relationships (Caterino and Tishechkin in review). However, the three are very different in appearance and this result cannot be regarded with great confidence. Chapischema shows no phylogenetic affinity with the superficially very similar Pyxister .

Etymology.

The name of this genus is from the Greek, meaning ‘pill-shaped’; feminine.