Baconia diminua, 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 : 147-149

Baconia diminua sp. n. Figs 40 G–H42A–B, G, I, K–LMap 12

Type locality.

BRAZIL: Santa Catarina: Nova Teutonia [27.18°S, 52.38°W].

Type material.

Holotype male: "BRAZIL: Nova Teutonia, Oct. 1978, 27°11' B[sic] 52°23', 300-500m, Plaumann" / "FMNH-INS 0000069306" (FMNH). Paratypes (2): same locality as holotype, 1: 27.ix.1957, under bark, F. Plaumann (FMNH), 1: ii.1979, F. Plaumann (FMNH).

Other material.

1: BRAZIL: São Paulo, Lençóis Paulista Duraflora, Fazenda Rio Claro, 22°49'19.0"S, 48°53'36.5"W, 5 yr-old Eucalyptus grandis stand, 8.ix.2006, C.A.H. Flechtmann (UNESP).

Diagnostic description.

Length: 1.7-1.8mm, width: 1.3-1.4mm; body elongate oval, subparallel-sided, humeri slightly wider, subdepressed, glabrous; color rufopiceous, faintly bronzy-metallic; head with frons more or less flat, ground punctation conspicuous, few sparse coarser punctures dorsad, frontal stria present only at upper corner of eye, absent across front, supraorbital stria variably present, frequently fragmented, usually detached from frontal stria; antennal scape short, club more or less circular; epistoma short, slightly convex along apical margin, faintly emarginate; labrum about 4 ×wider than long, apical margin shallowly emarginate; mandibles short, each with acute basal tooth; pronotum with sides weakly convergent in basal half, rather abruptly convergent to apex, lateral marginal stria descends to ventral edge of pronotum in posterior two-thirds, usually continuous with anterior marginal stria, but may be narrowly interrupted behind eye, lateral submarginal stria present in basal three-fourths, pronotal disk weakly depressed in anterolateral corners, ground punctation fine, very sparse, with slightly coarser secondary punctures sparsely scattered in lateral thirds, denser toward lateral margin; elytra with two epipleural striae, outer subhumeral stria absent, inner subhumeral stria present at extreme base, dorsal striae 1-4 slightly and progressively abbreviated mediad from apices, 4th stria weakly arched toward scutellum at base, 5th stria distinctly abbreviated from base and apex, shorter than 4th stria, sutural stria shorter than 5th, present only at middle third, elytral disk with small, sparse secondary punctures in apical one-fourth, extending further anterad toward middle; prosternal keel weakly emarginate at base, with more or less complete, subparallel carinal striae; prosternal lobe about two-thirds keel length, apical margin rounded, marginal stria present only at middle; mesoventrite weakly produced at middle, with marginal stria interrupted for about width of prosternal keel; mesometaventral stria sinuately arched forward, continuous laterally with inner lateral metaventral stria, which extends obliquely toward middle of metacoxa, outer lateral metaventral stria present as at most a basal fragment; metaventral disk moderately coarsely punctate at sides, impunctate at middle; abdominal ventrite 1 with single, complete inner lateral stria, lacking secondary punctures on middle portion, ventrites 2-5 with fine punctures at sides, more sparsely punctate across middle; protibiae tridentate, margin serrulate between; mesotibia with two marginal spines; outer metatibial margin with very small subbasal denticle; propygidium lacking basal stria, with fine ground punctation and slightly coarser, ocellate punctures uniformly separated by about their diameters, propygidial gland openings inconspicuous; pygidium with sparse ground punctation becoming slightly denser apically, with small secondary punctures very sparse in basal half. Male genitalia (Figs 42 A–B, G, I, K–L): T8 narrowly, acutely emarginate at base, ventrolateral apodemes with inner apices separated by about one-half T8 width, projecting beneath to about ventral midpoint, tapered apically, apical margin shallowly emarginate; S8 with halves fused along midline, basal emargination deeply sinuate, basal apodemes truncate, sides subparallel to near apex, expanded slightly apically, apices narrowly, obliquely truncate, with a few apical setae, apical emargination broad, arcuate; T9 with short, narrow, subacute basal apodemes, halves separated dorsally, ventrolateral apodemes acutely produced, slightly recurved proximad beneath, apices of T9 narrowly rounded, with single subapical seta on each side; T10 poorly sclerotized, with weak apical emargination; S9 with long narrow, medially keeled stem, head abruptly widened, sides parallel to apex, apices acute, curving slightly mediad, apical emargination broad, shallow, sinuate; tegmen with sides subparallel from base to about midpoint, narrowed to apex, apices subacute, tegmen very weakly curved in lateral aspect, apex more strongly deflexed, narrowed near base, with eversible subapical denticles ventrally; median lobe about one-fourth tegmen length; basal piece about one-fourth tegmen length.

Remarks.

While this species shares a type locality with Baconia slipinskii , and is generally quite similar, it does exhibit a number of consistent differences, both externally and in male genitalia. Baconia diminua is distinct in its narrower body form (Fig. 40G), in elytral striation, with the 3rd-sutural striae longer and progressively shorter mediad, in its lack of dense punctures across the 1st and any subsequent abdominal ventrites (Fig. 40H), and its rather dense lateral pronotal punctation. The 8th sternite of Baconia diminua is narrower and more elongate than that of Baconia slipinskii , and the apices are more distinctly acute, with a deep, narrowly arcuate median emargination between them. One female from São Paulo state is excluded from the type series since male genitalic characters cannot be confirmed.

Etymology.

This species’ name refers to the ‘diminishing’ length of the elytral striae as they approach the sutural.