Baconia glauca (Marseul, 1884)

Caterino, Michael S. & Tishechkin, Alexey K., 2013, A systematic revision of Baconia Lewis (Coleoptera, Histeridae, Exosternini), ZooKeys 343, pp. 1-297 : 247-249

Baconia glauca (Marseul, 1884) Figs 73C75Map 15

Phelister glaucus Marseul, 1884: 162; Pseudister glaucus : Bickhardt 1917: 165 Baconia glauca : Mazur 1990: 755.

Type locality.

INDONESIA: Sumatra: Serdang [3.51°N, 98.81°E].

Type material.

Holotype, (MNHN): not located. This species was explicitly described from a single specimen. The published type data is eastern Sumatra, Serdang, Tandjong Morawa, collected by B. Hagen.

Other material.

MALAYSIA, 1: Selangor: Penchala, Kuala Lumpur, 8.ix.1969, R. Pilet (CHSM).

Diagnostic description.

Length: 2.1mm, width: 1.7mm; body elongate oval, moderately strongly depressed, glabrous; color metallic blue dorsally (pygidia, elytra, pronotum, head), rufobrunneus ventrally; head with frons depressed at middle, ground punctation rather coarse, with few secondary punctures at middle and at upper margin, frontal stria complete across front, weakly sinuate at middle; antennal scape short, club nearly circular; epistoma convex, truncate apically; labrum about twice as wide as long, weakly depressed at middle, apical margin arcuate; mandibles short, each with strong, acute basal tooth; pronotum with sides weakly convergent, rounded to apex, lateral marginal stria descending to ventral edge in posterior half, continuous anteriorly with complete anterior marginal stria, lateral submarginal stria absent, pronotal disk weakly depressed in anterolateral corners, with fine ground punctation, conspicuous secondary punctures denser toward sides; elytra with two complete epipleural striae, outer subhumeral stria absent, inner subhumeral stria complete, dorsal striae 1-5 complete to base, weakly abbreviated apically, sutural stria present in apical half or more, fading to base, elytral disk with scattered secondary punctures in apical one-eighth; prosternum broad, keel truncate at base, with carinal striae complete, sinuate, separate; prosternal lobe slightly less than one-half keel length, apical margin bluntly rounded, with marginal stria well impressed only at middle; mesoventrite broadly emarginate, with marginal stria absent from middle two-thirds; mesometaventral suture arched forward, mesometaventral stria arched more strongly forward, transverse at middle, continuous laterally with oblique lateral metaventral stria, which extends posterad toward middle of metacoxa, metaventral disk coarsely punctate at sides, impunctate at middle; abdominal ventrite 1 with complete inner lateral stria and abbreviated outer lateral stria behind metacoxa, disk with coarse secondary punctures only at sides, ventrites 2-5 with sparse secondary punctures at sides, impunctate at middle; protibia tridentate, the middle tooth closer to apical than basal, outer margin serrulate between teeth; mesotibia with two very weak marginal spines; outer metatibial margin smooth; propygidium lacking basal stria, with sparse, fine ground punctation, with coarse secondary punctures sparsely but evenly interspersed, propygidial gland openings slightly elongate, about midway between anterior and posterior margins, about one-fourth from lateral corners; pygidium strongly convex, with dense, fine ground punctation and coarser, secondary punctation mainly along basal margin. Male genitalia (Fig. 75): T8 broad, sides subparallel, basal emargination very shallow, basal rim well sclerotized, ventrolateral apodemes reaching longitudinal midpoint beneath, separated by about two-thirds T8 width; S8 halves approximate near bases, with conspicuous basal pore clusters on each side, inner margins rapidly diverging apically, sides divergent, apical guides poorly developed, apices connected by ventral velar membrane with vague sclerotizations; T9 with proximal apodemes thin, about one-half total length, dorsal lobes fused at middle, apices narrow, with convergent digitiform apical processes, ventrolateral apodemes well developed, dentate beneath; S9 stem strongly desclerotized along midline, nearly divided to base, sides narrowed to base, apical arms divergent, slightly recurved; tegmen broad at base, evenly narrowed to apex, thin in lateral aspect, curving ventrad in apical half; median lobe simple, about two-thirds tegmen length; basal piece widening apically to width of tegmen, almost two-thirds tegmen length.

Remarks.

Surprisingly, this species is not closely related to the other Asian Baconia , thoseof the Baconia aeneomicans group. Its male genitalia are in fact highly divergent from anything else in the genus. Externally, its metallic blue coloration (Fig. 73C), strongly depressed body form, and 4th dorsal stria ending free at base, not arched mediad toward the suture, will distinguish it easily from all other known SE Asian species.

Despite the fact that we have not been able to study the type specimen, Marseul’s description is perfect compatible with the specimen we attribute to this species, and is inconsistent with any of the members of the Baconia aeneomicans group known from SE Asia.