Baconia haeterioides, Caterino, Michael S. & Tishechkin, Alexey K., 2013

Caterino, Michael S. & Tishechkin, Alexey K., 2013, A systematic revision of Baconia Lewis (Coleoptera, Histeridae, Exosternini), ZooKeys 343, pp. 1-297 : 235-236

Baconia haeterioides sp. n. Figs 69 D–F70D–F, I–J, LMap 20

Type locality.

BRAZIL: Minas Gerais: Ingaí Municipality [21.3°S, 44.9°W].

Type material.

Holotype male: "BRASIL: Minas Gerais, Ingaí Municip., Boqueirão, Res. Nr. Lavras. Rocky field flight intercept trap December 2002. R.J.Silva" / “LSAM0047469” (CEMT). Paratype (1): BRAZIL: Goias: Paraiso, 8-14.ii.1962, J. Běchyně (CHND).

Diagnostic description.

Length: 1.8-2.0mm, width: 1.2-1.3mm; body elongate, subparallel-sided, constricted at humeri, rather strongly depressed, most dorsal surfaces distinctly, sparsely punctate, bearing short, narrowly acute scale-like setae; rufobrunneus throughout; frons transversely carinate between antennal bases, flattened above, epistoma very broad, flat to weakly concave below, delimited above by distinct, complete frontoclypeal suture; frontal disk sparsely punctate, frontal stria only vaguely indicated by punctures along inner edge of eyes; labrum extremely wide, about 8 ×wider than median length, extending laterad beyond sides of epistoma, broadly and deeply arcuate; mandibles strongly bent at anterolateral corners, inner apices long, both with strong, acute median tooth; antennal scape strongly expanded apically, irregularly triangular, club small, elongate oval, basal two-thirds glabrous and shining, with sensory openings distinct; pronotal sides strongly, unevenly rounded, narrowed basally, with small, rather inconspicuous trichome on opposing surfaces of hypomeron and mesepisternum, barely visible from above; pronotal sides depressed to explanate; marginal pronotal stria obsolete in basal half, otherwise more or less continuous along lateral and anterior margins, lateral submarginal stria absent; pronotal discal punctation sparse throughout, dual, with larger punctures setigerous; elytral sides subparallel but strongly narrowed to humeri, shallowly depressed along basal margin, with one complete epipleural stria, outer subhumeral stria very briefly indicated at base, inner subhumeral stria present in basal half to two-thirds, dorsal striae 1-2 more or less complete, 3 rd– 5th striae progressively abbreviated from apex, sutural stria longer, more or less complete, setigerous punctures of elytra smaller and more uniform than those of pronotum; prosternum narrow basally, weakly convex, keel truncate at base, carinal striae united along basal margin, subparallel in basal third, diverging anterad; prosternal lobe about one-half keel length, apical margin truncate to weakly emarginate, weakly deflexed, marginal stria fine, obsolete at sides; mesoventrite with anterior margin finely and weakly produced, marginal stria very close to margin, fragmented at middle, mesometaventral stria present as detached fragments on each side; lateral metaventral stria extending posterolaterad toward outer third of metacoxa, outer lateral stria short, vaguely indicated, metaventral disk with only conspicuous, sparse ground punctation medially; abdominal ventrite 1 with single complete lateral stria, middle portion of disk punctate as metaventrite; protibia broad, somewhat swollen, with 3-4 weak teeth, outer margin not serrulate between teeth; meso- and metatibiae weakly expanded, flattened, mesotibia with 2 very weak marginal spines; outer metatibial margin smooth; propygidium without basal stria, with only sparse setigerous punctures; pygidium strongly produced at middle, with large, expanded, setose depressions on each side, above and below, the margin between upper and lower trichomes finely carinate, glabrous, pygidial disk otherwise impunctate. Male genitalia (Figs 70 D–F, I–J, L): T8 slightly elongate, basal emargination shallow, sides subparallel, ventrolateral apodemes only projecting beneath basal half, their apices separated by half T8 width; S8 halves rather narrow, approximate at bases, inner margins diverging apically, sides subparallel, apical guides well developed, apices bluntly rounded; T9 with proximal apodemes nearly half entire length, apices narrowly rounded, convergent, ventrolateral apodemes short, blunt; T10 apically emarginate; S9 stem desclerotized along midline, weakly widened toward base, apical arms divergent, curving distad, apical emargination broad, shallow; tegmen narrow, long, sides sinuate, widest near base, narrowed about one-third from apex, apex slightly widened, weakly curved ventrad in apical half; median lobe very short, about one-fifth tegmen length; basal piece about one-fifth tegmen length.

Remarks.

A diagnosis is almost superfluous for this remarkable species. The very conspicuous pygidial trichomes immediately distinguish it from any other Neotropical histerid (Figs 69D, F). The presence of trichomes and the unusual expansion of the antennal scapes first led us to think this might be an aberrant member of Haeteriinae . However, the distinctive sensoria of the antennal club make its inclusion in Baconia unambiguous, and it in fact shares a number of characters with several other species in the Baconia famelica group, especially the setigerous, punctate cuticle, the truncate/emarginate prosternal lobe, the basally glabrous antennal club, and the transversely carinate frontal margin (Fig. 69E). It shares its broadened tibiae with Baconia cavifrons (also first considered an Haeteriine), but is probably more closely related to Baconia fortis , Baconia longipes , and Baconia redemptor .

The trichomes of this species clearly suggest a myrmecophilous habit. Unfortunately both known specimens appear to have been collected in passive traps, and no such data exists. The ‘Paraiso’ locality in Goias is somewhat ambiguous. We suggest this is from Alto Paraiso in the northeastern part of the state.

Etymology.

This species’ name alludes to its similarity to some Haeteriinae , particularly in its prominent trichomes and probable inquilinous habits.