Conocassis, 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 : 12-14

Conocassis gen. n.

Type species.

Conocassis minor sp. n.

Description.

Size range: Length 1.7-2.0 mm; width 1.2-1.5 mm; Body: rufescent to rufobrunneus, somewhat narrowly elongate, widest at humeri, abruptly narrowed anteriorly at pronotal middle, with exaggerated sculpturing throughout. Head: head deflexed relative to anterior pronotal margin; frons flat, sides weakly rounded, longitudinally strigose, with fine setigerous punctures between strigae, setae minute; frontal stria complete along margin of eye and across front, prominent, descending onto epistoma anteriorly, subangulate at middle; supraorbital stria absent; epistoma narrowed to front, apex rather narrowly emarginate, with lateral striae meeting frontal stria, convergent, nearly meeting anterad; labrum small, about twice as wide as long, apex weakly emarginate; mandibles with incisor edges evenly curved to apex, basal teeth inconspicuous; submentum broadly triangular, weakly produced into base of oral cavity, sparsely setose; mentum subtrapezoidal, apex weakly sinuate; labial palpifers prominent; labial palps 3-segmented, with basal palpomere very short, apical palpomere widest near base, subacute; maxillary cardines short, semicircular, glabrous, stipes with two setae along lateral margin; maxillary palpi 4-segmented with basal palpomere very short, palpomeres 2 and 3 similar in length and breadth, ultimate palpomere about twice as long as penultimate, widest near base, narrowed apically; antennal scape stout, anterior surface becoming longitudinally carinate in apical half, with few apical setae; funicle widening slightly to short, disclike 8th antennomere; antennal club about 2.5 × as long as wide, densely setose, with indistinct, denser subapical setose sensory patches on dorsal and ventral surfaces. Pronotum: widest near base, sides sinuate, strongly narrowed anterad midpoint, basal margin uneven; lateral marginal pronotal stria complete around lateral and anterior margins, though strongly sinuate at sides, submarginal stria present along sides, not parallel to marginal, joining it near anterior corner; pronotal disk with prominent dorsal process arising from entire anterior margin, narrowing and arcing more or less evenly to middle of posterior margin, sides of process longitudinally creased to deeply invaginated, dorsal surface of process coarsely reticulostrigose, sides more or less smooth; pronotal gland openings, if present, obscured by sculpturing, possibly incorporated into lateral invaginations of pronotal process. Elytra: elytron with striation generally carinate and exaggerated; epipleuron with complete marginal stria and additional stria along upper edge, paralleling outer subhumeral stria, continuing around elytral apex, variably meeting apices of dorsal striae; outer subhumeral, inner subhumeral, and dorsal striae 1-4 all complete, increasingly more strongly impressed toward suture, apices meeting apical marginal elytral suture; elytral intervals smooth to strongly microsculptured. Prosternum: prosternal keel rather narrow, base weakly produced, carinal striae complete, subparallel, united basally, meeting presternal suture anteriorly, which varies from indistinct to deeply impressed; lateral striae diverging to sides, delimiting anterior leg depression; prosternal lobe extremely reduced, no longer at midline than at sides, marginal stria obsolete. Mesoventrite: mesoventrite short, shallowly emarginate at middle, with complete marginal stria; mesometaventral stria paralleling or diverging anterad from mesometaventral suture at middle. Metaventrite: postmesocoxal and lateral metaventral striae parallel, arching toward metacoxa then anterad to metepisternum; metaventral disk weakly depressed at middle. Abdomen: 1st abdominal ventrite with anterior marginal stria continued to posterior margin by lateral striae, disk rather simply and finely punctate; propygidium slightly to distinctly wider than long, rather strongly convex, sparsely to densely reticulostrigose; propygidium apparently with single pair of gland openings very close to anterior corners (obscured by sculpturing in most species); pygidium longer than basal width, sculptured as propygidium, generally smoother apicomedially. Legs: each trochanter with single seta; profemur subparallel-sided to expanded at middle of anterior margin, with anterior marginal stria delimiting microsculptured marginal area; protibiae widened from base, sides subparallel to slightly narrowing, bearing 3-5 marginal setae in apical half; protarsal groove very weakly developed; meso- and metafemora rather large, produced beyond epipleurae in repose, broad, variously widened along posterior margins; meso- and metatibiae long, widened apically, bearing 3-4 longitudinal striae on anterior surfaces; mesotibia only bearing 2-4 characteristic long, thin subapical setae, at least one of which is inserted on the posterior surface; all tarsi laterally compressed, bearing simple ventral setae, with relatively large weakly curved claws. Male genitalia (Fig. 4): Paired accessory sclerites present; T8 with broad basal and narrower apical emarginations, line of basal membrane attachment complete, just distad basal emargination, ventral apodemes well developed, nearly meeting along midline; S8 with halves separated, apical guides moderately and evenly developed from base to apex, each apex with single prominent seta; 9th tergite with very weak ventrolateral apodemes, apices narrow, subacute; T10 completely divided; S9 broad at base, narrowest near apex, head broad, subquadrate apically, with small apical emargination, more strongly sclerotized along midline; tegmen broad basally, strongly narrowed to apex, narrowly divided apically, median foramen basad apical narrowing, moderately to strongly curved ventrad in apical half; basal piece about one-third tegmen length; median lobe short, simple, from one-fourth to one-third tegmen length. Female genitalia: T8 forming a single plate, apically emarginate; S8 tripartite, basal baculi convergent proximally; S9 elongate, articulated with strap-shaped extension from apex of S8; T10 entire; overall ovipositor rather short; valvifers paddle-shaped, paddles nearly one-half total length; coxites strong, slightly longer than broad, two-thirds length of valvifers, strongly bidentate, with strengthening ridge on inner face; gonostyle present; bursa copulatrix membraneous, weakly expanded; spermatheca gradually expanded, apically bulbous, with slightly expanded spermathecal gland attached near its base.

Diagnosis.

This highly distinctive genus scarcely needs a diagnosis. Its prominent pronotal process (Figs 1, 2) is unique and unmistakable. Its assignment perhaps to tribe could be problematic, as it exhibits no hint of an emargination of the prosternal keel (Fig. 3 A–B). However, both male and female genitalia, as well as DNA sequences place it unambiguously as deeply nested within the neotropical Exosternini .

Remarks.

Phylogenetic analyses to date place Conocassis as the sister group of Kaszabister , a group of 4 species which are inquilines of fire ants ( Solenopsis spp.) (Caterino and Tishechkin in review). There are few obvious similarities between these apart from generally exaggerated surface sculpturing (to a much lesser degree in Kaszabister ). We were very fortunate to have collected a DNA quality specimen of Conocassis minor during our own fieldwork, its sequence providing some confidence in its general placement. Kaszabister , on the other hand, has not yet been sequenced, so a more rigorous test of their close relationship remains to be carried out.

Etymology.

The genus name means 'conical helmet’ referring to the anterior process of the pronotum. The gender of the name is feminine.

Key to species of Conocassis