Baconia cavifrons (Lewis, 1893)

Caterino, Michael S. & Tishechkin, Alexey K., 2013, A systematic revision of Baconia Lewis (Coleoptera, Histeridae, Exosternini), ZooKeys 343, pp. 1-297: 232-234

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scientific name

Baconia cavifrons (Lewis, 1893)

comb. n.

Baconia cavifrons (Lewis, 1893)   comb. n. Figs 69 A–C70A–C, G–H, KMap 20

Homalopygus cavifrons   Lewis, 1893: 421.

Type locality.

BRAZIL: Rio de Janeiro: [22.9°S, 43.2°W].

Type material.

Lectotype, sex undetermined, here designated (BMNH): "Fry, Rio Jano." / "Homalopygus cavifrons Lewis Type" / "G.Lewis Coll. B.M.1926-369" / "LECTOTYPE Homalopygus cavifrons Lewis, 1893 M.S.Caterino & A.K.Tishechkin des. 2010". Paralectotypes (3): same data as type (BMNH, FMNH). This species was explicitly described from 'several specimens’, and the lectotype designation fixes primary type status on one of the original specimens.

Diagnostic description.

Length: 2.4-2.5mm, width: 1.7-1.8mm; body narrowly elongate, parallel-sided, moderately depressed, ground punctation rather conspicuous throughout; rufobrunneus; frons elevated over antennal bases, ridges more or less continued anterad onto epistoma and meeting across a distinct apical epistomal ridge, frons deeply depressed above this ridge, punctation of frontal disk coarse along raised ridges, finer between, with few deeper punctures in median area; frontal stria present along eyes, absent across middle; labrum large, about 4 ×wider than long, apical margin distinctly emarginate; mandibles with elongate api ces and strong, acute median teeth; antennal scape short, obliquely truncate apically, club small, subspherical, completely tomentose; pronotal sides parallel in basal four-fifths, abruptly narrowed to apices, marginal stria complete along lateral and anterior margins; lateral submarginal pronotal stria absent, pronotal disk not depressed in anterior corners; pronotal ground punctation conspicuous throughout, with secondary punctures becoming larger and denser laterally and, to a lesser degree, anteriorly, relatively impunctate basomedially; elytra with two complete epipleural striae, outer subhumeral stria absent, inner subhumeral stria present as very short basal fragment, dorsal striae 1-3 complete, 4th and 5th striae largely absent, but a short basal arch present probably representing 5th dorsal stria, sutural stria present in apical two-thirds, elytral disk with scattered secondary punctures in apical fourth and extending further forward between 3rd and sutural striae; prosternum narrow basally, weakly convex, keel very weakly emarginate at base, carinal striae approximate basally, diverging anterad; prosternal lobe about one-half keel length, apical margin bluntly rounded, deflexed, marginal stria present at middle, obscured by punctures at sides; mesoventrite quadrate, weakly produced at middle, marginal stria complete, mesometaventral stria weakly arched forward, crenulate; lateral metaventral stria extending obliquely posterolaterad toward middle of metacoxa, obsolete in apical half, outer lateral stria nearly as long, metaventral disk impunctate at middle; abdominal ventrite 1 with complete inner lateral stria and short fragments of outer stria, middle portion of disk impunctate; protibia with outer margin arcuate, bearing 7-8 distinct teeth, outer margin not distinctly serrulate between; meso- and metatibiae (and femora) rather elongate, mesotibia parallel-sided with series of about 7 marginal spines; outer metatibial margin with only 2-3 marginal spines; propygidium without basal stria, discal punctures rather large, ocellate, densest along basal margin, sparser at middle; propygidial gland openings conspicuous, about one-third from anterior and lateral margins; pygidium with secondary punctures moderately large, separated by their diameters in basal two-thirds, abruptly sparser in apical third. Male genitalia (Figs 70 A–C, G–H, K): T8 slightly wider than long, basal emargination shallow, sides rounded, converging apically, apical emargination narrow, ventrolateral apodemes well sclerotized, only weakly projecting beneath; S8 short, halves rather narrow, approximate at bases, inner margins diverging apically, sides subparallel, apical guides well developed, apices bluntly rounded, bearing a few inconspicuous setae; T9 with proximal apodemes about one-third entire length, apices narrowly rounded, convergent, ventrolateral apodemes short, barely recurved proximad; T10 elongate; S9 stem desclerotized along midline, weakly widened toward subtruncate base, apical arms divergent, curving distad, apical emargination broad, shallow; tegmen narrow, long, sides only very weakly narrowed near apex, weakly curved ventrad in apical third; median lobe about one-fourth tegmen length; basal piece about one-fourth tegmen length.


This species may be most easily distinguished by its elongate, subdepressed body form (Fig. 69A), in combination with the deeply depressed frons and rather long, relatively spinose legs (Fig. 69B, C). Its original description in Homalopygus   is difficult to understand, as its similarity to members of that Haeteriine genus seems obviously superficial. However, it is certainly not very similar to any other Baconia   species, so its persistent assignment to Homalopygus   may simply be due to difficulty in determining a better placement. Its antennal club’s sensory foveae make its assignment to Baconia   unambiguous, despite its numerous unusual characters.