Balligratus brevis, Moret, Pierre & Ortuño, Vicente M., 2017

Moret, Pierre & Ortuño, Vicente M., 2017, Balligratus, new genus of wingless ground beetles from equatorial Andean montane forest (Coleoptera: Carabidae: Lachnophorini), Zootaxa 4258 (2), pp. 101-120 : 111-114

Balligratus brevis sp. nov.

Holotype, ♂, ECUADOR: Provincia Chimborazo, Tungurahua sud, Río Puela , 2,750 m, 1.V.1985, leg. P. Moret ( MNHN).

Paratypes, 2 ♂, same data as the holotype ( CPM, QCAZ) .

Description. Overall body length: 5.31–5.70 mm. Short species with broad pronotum and oval elytra ( Fig. 7 ). Body tegument brunneopiceous, shiny; appendages and labrum testaceous; clypeus flavotestaceous.

Dimensions of the head: HL 0.77–0.79 mm; HW 1.06–1.13 mm. Disc with a weak isodiametric microsculpture. Antennae reaching the basal third of the elytra when laid along side margin. Labium: Fig. 8 a.

Pronotum slightly transverse (PL 1.06–1.11 mm; PW 1.36–1.50 mm; PL/PW = 0.74–0.78), wider than head, convex, trapezoidal in shape with rounded angles; its maximum width slightly anterad middle. Microsculpture of the disc transverse and shallow. Sides markedly arcuate in distal half, convergent and subrectilinear in basal half; hind angles obtuse-rounded; anterior angles feebly protruding; lateral groove markedly narrow; basal margin hardly sinuate medially. Basolateral depressions small and shallow, ill defined. Lateral seta inserted at base of the distal third of the lateral margin. Prosternal apophysis elongate, subelliptical at apex, distinctly bordered along basal margins ( Fig. 8 b).

Elytra broad (EL 2.90–3.15 mm; EW 2.11–2.25 mm; EW/EL = 0.71–0.74; PW/EW= 0.62–0.66), oval in shape, with narrowed and feebly marked humeri. Maximum width at middle. Basal bead sinuate. Microsculpture of the disc transverse and shallow. All striae well impressed; intervals flat. Scutellar striole well marked. Anterior discal seta adjoining the 3rd stria at the height of the humeral umbilicate series; postmedian seta adjoining the 2nd stria at the height of the 7th or 8th seta of the umbilicate series; 13 umbilicate setae in the ninth interval, distributed 5 / 1 / 7.

Legs relatively short; meso- and metatarsi stocky in relation to the overall body length (MstL 0.80–0.81 mm; MttL 1.10–1.15 mm; [MstL+MttL]/BL = 0.34–0.35). Basal three tarsomeres slightly bisulcate dorsally, sulci deeper on the first tarsomere.

Apical margin of the last visible abdominal ventrite simply arcuate ( Fig. 8 c).

Male genitalia ( Fig. 8 d–h): median lobe relatively large (MLL 1.25–1.27 mm; MLL/BL = 0.23), swollen medially, its ventral margin bisinuate in lateral view; apex slightly bent downwards, obtusely hammer-shaped in lateral view, spatulate-rounded in dorsal view; basal bulb reduced. Left paramere large, simply oval; right paramere small, with a hook-like basal process; bifid distally with a denticulate subapical lobe and a rounded apical lobe. Ring sclerite elongate, narrowly ovate.

Female unknown.

Comment. The holotype has the discal setae of the elytra inserted as usual in Balligratus , with seta 1 adjoining the 3rd stria and seta 2 adjoining the 2nd stria, whereas one paratype has seta 2 close to the 3rd stria on the right elytron, and the other paratype shows the same disposition on the right elytron and lacks seta 2 on the left elytron.

Etymology. Latin adjective meaning “short”.

Distribution. Pacific slope of the Western Cordillera in Central Ecuador, in the upper montane forest ( Fig. 11 ). Type locality at 1°30’27” S / 78°27’36” W.

Way of life. The type specimens were found together under a rotten log.

Figures

FIGURE 7. Balligratus brevis sp. nov., male holotype, habitus in dorsal view. Scale bar: 1 mm.

FIGURE 8. Balligratus brevis sp. nov., details of ventral side and male genitalia. a: labium; b: prosternal apophysis; c: last visible abdominal ventrite (male); d: ring sclerite; e: median lobe, left lateral view; f: median lobe, dorsal view; g: left paramere; h: right paramere. Scale bars: 0.5 mm.

FIGURE 11. Distribution of Balligratus gen. nov. in Ecuador. The ochre to brown area roughly corresponds to the montane pluvial forest. White squares: described species; black squares: undescribed species. Map base © OpenStreetMap contributors.