Baconia chilense (Redtenbacher, 1867)

Caterino, Michael S. & Tishechkin, Alexey K., 2013, A systematic revision of Baconia Lewis (Coleoptera, Histeridae, Exosternini), ZooKeys 343, pp. 1-297 : 244-247

Baconia chilense (Redtenbacher, 1867) Figs 73 A–B 74Map 22

Platysoma chilense Redtenbacher, 1867: 32; Pseudister chilensis : Johnson in Johnson et al. 1991: 12; Baconia chilensis : Mazur 1997: 25.

Hister impressifrons Solier, 1849: 379 (not Blanchard 1843); Phelister impressifrons : Marseul 1861: 159; Phelister impressifrons : Lewis 1905: 48; Pseudister impressifrons : Bickhardt 1917: 165; junior primary homonym.

Type locality.

CHILE [exact locality unknown]

Type material.

We have been unable to locate type material for either the junior or senior synonym of this species. However, because only a single Baconia species is known from Chile, because Marseul identified some available specimens as Solier’s species (with which he would have been familiar), and because all previous authors have agreed on its identity, we feel very confident in this species’ identity, and do not feel that the designation of a neotype is necessary.

Other material.

CHILE: 39: Cautín: Cherquenco, W. of Volc. Laima, 38°21'S, 72°00'W, i.1954, L. Pena (FMNH); 2: Fdo Las Selvas, N.W. Nueva Imperial W. Temuco, 600-700 m, 18.ii.1981, L. Pena (USNM, MHNG); 1: Llanquihue: N.W. Shore, Lago Chapo, 41°27'S, 72°30'W, 250 m, 13.xi.1966, M. Irwin & E. Schlinger (CASC), 1, 14.ii.1982, G. Arriagada (MHNG); 1: Valdivia: Rincon de la Piedra, turnoff 14.8 km SE Valdivia, 39°55.32'S, 73°06.27'W, 50 m, 2.ii.1997, under bark, disturbed Valdivian rainforest w/ Nothofagus dombeyi , Podocarpus saligna , Persea lingue log, A. Newton & M. Thayer (FMNH); 2: [country record only] (BMNH).

Diagnostic description.

Length: 2.2-2.4mm, width: 1.8-1.9mm; body elongate oval, humeri prominent, moderately depressed, glabrous; piceous, shining, not metallic; frons elongate, weakly elevated over antennal bases, depressed along midline, in terocular margins rounded, convergent dorsad, frontal stria nearly complete, narrowly interrupted or disrupted by punctures at middle, frontal disk with few coarse punctures in median depression and toward vertex, supraorbital stria absent; epistoma flat to weakly depressed in middle, apical margin straight; labrum broadly emarginate to weakly bisinuate; mandibles each with basal tooth; antennal scape short, club broadly rounded; pronotal sides weakly convergent in basal two-thirds, more strongly arcuate to apices, lateral marginal striae continuous around sides and front, submarginal stria present, merging with marginal stria about one-fourth behind anterior corner, pronotal disk with anterior corners depressed, coarsely punctate along most of posterior margin, with shallow discal punctures present in anterior half and lateral third, only fine ground punctures present at middle; elytra with two complete epipleural striae, outer subhumeral stria absent, inner subhumeral stria nearly complete, slightly abbreviated at apex, dorsal striae 1-3 complete, 4th stria abbreviated from base and apex, 5th and sutural striae absent, elytral disk with small, sparse punctures in apical third; prosternal keel broad, weakly convex, truncate to weakly emarginate at base, carinal striae subparallel basally, diverging anterad, complete, may be united along basal margin; prosternal lobe short, about one-half keel length, apical margin deflexed, subtruncate, marginal stria absent; mesoventrite sinuate to weakly produced at middle, marginal stria broadly interrupted; mesometaventral stria arched strongly forward displacing marginal stria, not crenulate, narrowly detached from inner lateral metaventral stria, which curves posterolaterad toward outer third of hind coxa, slightly abbreviated apically, outer lateral metaventral stria short, oblique; metaventral disk impunctate at middle; abdominal ventrite 1 with inner lateral stria complete, outer stria short, apical, median portion of disk with few punctures near apices of lateral stria; protibia 4-5 dentate, basal denticles weak, outer margin finely serrulate between spines; mesotibia with two weak marginal spines; outer metatibial margin smooth; propygidium lacking basal stria, with rather large, shallow secondary punctures separated by slightly less than their diameters in middle, smaller and sparser to sides, propygidial glands conspicuous, about midway back from anterior margin, about one-fifth from lateral corners; pygidium short, with fine ground punctation interspersed with secondary punctures, mainly in basal half. Male genitalia (Fig. 74): T8 broad, sides rounded, basal emargination deeply arcuate, apical emargination shallow, ventrolateral apodemes reaching one-third from base beneath; S8 halves approximate near bases, inner margins rapidly diverging apically, sides divergent, apical guides developed toward apex, apices broadly rounded; T9 with proximal apodemes short, dorsal lobes broad at middle apices narrowly rounded, convergent, ventrolateral apodemes very weakly developed; S 9 stem desclerotized along midline, sides narrowed, one-third from base, apical arms divergent, curved, apical emargination broad, shallow; tegmen narrow, sides weakly narrowed one-third from apex, weakly curved ventrad at extreme apex; median lobe about one-half tegmen length; basal piece about one-fourth tegmen length.

Remarks.

While the distribution of this species alone is diagnostic, it has a number of other distinguishing characters in the genus, including the prominent, swollen humeri (Fig. 73A), the relatively broad prosternal keel (unusual among less obviously flattened species), and displaced mesoventral marginal stria (Fig. 73B). In many respects it resembles members of the Baconia godmani group, and it may be close to that group, although the male S8 is neither elongate nor setose.