Labus obtusus Nguyen & Carpenter, 2020

Nguyen, Lien Thi Phuong & Carpenter, James M., 2020, Potter wasps of the genus Labus (Hymenoptera, Vespidae, Eumeninae) from Vietnam, with description of two new species, Journal of Hymenoptera Research 77, pp. 139-150 : 139

Labus obtusus Nguyen & Carpenter sp. nov.

Figs 8-14

Material examined.

Holotype, male, Vietnam: Bidoup Nui Ba NP, Da Chais, Lac Duong, Lam Dong, 12°08'403"N, 108°38'56.3"E, alt. 1428 m, 4 Jun. 2013, Nguyen TPL leg., deposited in IEBR . Paratype: 1 male, same data as holotype .

Dianosis.

This species can be distinguished from all other congeners by following combination of characters: Propodeum with posterior excavation not margined above; metasomal segment I with swollen part longer than half the total length of the petiole; TI in dorsal view slightly less than 9 times as long as wide at base; TII in dorsal view almost as wide as long.

Description.

Male (Fig. 14 ). Body length 6.9-7.1 mm (holotype 6.9 mm); fore wing length 5.9-6.1 mm (holotype 5.9 mm).

Head in frontal view subcircular, about 1.2 times as wide as high (Fig. 8 ). Head without frontal fovea. Gena slightly narrower than eye; occipital carina complete, present along entire length of the gena. Inner eye margins strongly convergent ventrally; in frontal view nearly 1.6 times further apart from each other at vertex than at clypeus (Fig. 8 ). Clypeus in lateral view prominently convex at basal half, then straight to apical margin; in frontal view nearly as wide as long (Fig. 8 ), with basal margin slightly convex medially and distinctly separated from antennal sockets; apical margin emarginated medially, forming a sharp tooth on each lateral side (Fig. 8 ); width of the emargination less than 1/4 width of clypeus between inner eye margin. Mandible with four prominent teeth. Antennal scape about 4.2 times as long as its maximum width, curved; FI about 1.8 times longer than wide, FII-III longer than wide, FIV - VIII wider than long, FXI nearly 1.2 times as long as wide, FX small, FXI thin, slightly curved, and long, slightly more than 5 times as long as wide (Fig. 9 ).

Mesosoma longer than wide in dorsal view (Fig. 10 ). Pronotal carina raised, pronotal corner slightly produced to form short and blunt projection (Fig. 10 ). Mesoscutum weakly convex, 1.1 times as long as wide between tegulae. Scutellum weakly convex, in lateral view at the same level as mesoscutum. Metanotum with a short, tooth-like, blunt tubercle in the middle. Propodeum (Fig. 11 ) excavated in the middle apically, with posterior excavation not margined above, with a distinct median longitudinal furrow except the middle part with short transverse striation, border between posterior and lateral surfaces rounded.

Metasomal segment I much narrower than segment II, swollen part slightly longer than half of the length of the petiole (0.55 times as long as the total length of the petiole) (Fig. 12 ). TI in dorsal view about 8.8 times as long as wide at base, and 3.1 times as long as wide at apex (Fig. 12 ); TII with thick lamella, almost as wide as long in dorsal view; SII in lateral view almost straight to one-third from base, then slightly convex and straight to apical margin (Fig. 13 ).

Body covered with short, silver hairs except clypeus, mandible and lower part of propodeum with dense long silver hairs.

Clypeus with sparse and shallow punctures in the middle area, almost smooth at sides. Frons densely covered with very coarse punctures, border between punctures not raised. Vertex and gena with punctures similar to those on frons. Pronotum with punctures coarser than punctures on vertex and gena, spaces between punctures raised to form reticulation. Mesoscutum densely and coarsely covered with flat-bottomed punctures, punctures on scutellum dense, coarse and equal to those on mesoscutum, punctures on metanotum smaller. Mesepisternum with punctures similar to those on pronotum posterodorsally, minute punctures anteroventrally; border between posterodorsal and anteroventral parts indistinct. Dorsal metapleuron with some long striae, ventral metapleuron with short striae at inner side, and with some sparse shallow punctures. Propodeum with sparse and strong punctures on dorsal and posterior parts, punctures on lateral parts sparser and shallower. TI densely covered with strongly rugose punctures on basal half, with sparse and strong punctures on apical half, TII with sparse and small punctures.

Colour. Body black; following parts yellow: clypeus except black apical margin, large spot on each side of pronotum, two transverse spots on scutellum, spot on apical spine, outer side of tegulae and parategulae; apical band of TI, II and SII. Legs black; following parts yellow: spot at apical margin of middle femur and hind tibia, middle tibia entirely.

Female. Unknown.

Distribution.

South Vietnam.

Remarks.

This species comes close to Labus angulus sp. nov. in having the swollen part of metasomal segment I longer than half of the total length of the petiole, and propodeum with posterior excavation not margined above, but it is different from the latter in having the pronotum with short and blunt projections at lateral corners (pronotum with long and sharp projections at lateral corners in L. angulus ).

Etymology.

The specific name refers to the obtuse lateral projections at the corners of the pronotum.

Figures

Figures 8 - 14. Labus obtusus sp. nov., holotype male 8 head, frontal view 9 right antenna 10 mesosoma, dorsal view 11 propodeum, posterior view 12 TI, dorsal view 13 metasomal segments, lateral view 14 habitus. Scale bars: 0.5 mm.