Labus angulus 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 angulus Nguyen & Carpenter sp. nov.

Figs 1-7

Labus clypeatus van der Vecht, 1935: Nguyen et al. 2014: 11, misidentification.

Material examined.

Holotype, female, Vietnam: Dien Bien, 21°56'16.7"N, 102°52'58"E, alt. 500 m, 22 Jul. 2009, Nguyen TPL, Pham HP & Kojima J leg., deposited in IEBR.

Dianosis.

This species can be distinguished from all other congeners by the following combination of characters: Propodeum with posterior excavation not margined above; metasomal segment I long and slender, swollen part slightly longer than half the total length of the petiole; TI in dorsal view more than 9 times as long as wide at base; TII with thick lamella, about 1.16 times as long as wide in dorsal view; female frontal fovea much larger than anterior ocellus, oval.

Description.

Female (Fig. 7 ). Holotype: Body length 7.2 mm; fore wing length 6.2 mm.

Head in frontal view subcircular, about 1.1 times as wide as high (Fig. 1 ). Head with frontal fovea much larger than anterior ocellus, oval, with distinct border (Fig. 2 ). Gena almost as wide as eye; occipital carina complete, present along entire length of the gena. Inner eye margins strongly convergent ventrally, in frontal view nearly 1.45 times further apart from each other at vertex than at clypeus (Fig. 1 ). Clypeus in lateral view prominently convex at basal half, then slightly depressed and bent backward to apical margin; in frontal view about 1.18 times as wide as high (Fig. 1 ), with basal margin slightly convex medially and distinctly separated from antennal sockets; apical margin emarginated medially, forming a sharp tooth on each side (Fig. 1 ); width of the emargination about 1/4 width of clypeus between inner eye margin. Mandible with four prominent teeth. Antennal scape about 4.4 times as long as its maximum width, curved; FI about 1.26 times longer than wide, FII-III longer than wide, FIV-IX wider than long, terminal flagellomere bullet-shaped, as long as its basal width.

Mesosoma longer than wide in dorsal view (Fig. 3 ). Pronotal carina raised, pronotal corner strongly produced to form long and sharp projection (Fig. 2 ). Mesoscutum weakly convex, 1.2 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, sharp tubercle in the middle. Propodeum (Fig. 4 ) excavated in the middle apically, with posterior excavation not margined above, with a distinct median longitudinal furrow, rounded between posterior and lateral surfaces.

Metasomal segment I much narrower than segment II, swollen part slightly longer than half of the length of the petiole (0.56 times as long as the total length of the petiole) (Fig. 5 ). TI in dorsal view about 9.35 times as long as wide at base, and 3.45 times as long as wide at apex (Fig. 5 ); TII with thick lamella, about 1.16 times as long as wide in dorsal view; SII in lateral view almost straight from base to one-third, and slightly convex then straight to apical margin (Fig. 6 ).

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

Clypeus with dense, coarse punctures in the middle area, punctures sparser and smaller at sides, each puncture bearing a silver bristle. Frons densely covered with very coarse punctures, border between punctures with minute punctures and raised to form reticulations. Vertex and gena with punctures similar to those on frons. Pronotum with punctures coarser than punctures on vertex and gena. Mesoscutum densely and coarsely covered with punctures similar to those on pronotum, punctures on scutellum dense, coarse and equal than 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 long striae, ventral metapleuron with short striae at inner side, and with 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 orange-yellow: an arcuate transverse band at basal margin of clypeus, 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 and II. Spot near apical margin of metasomal segment I brown. Legs black; following parts orange-yellow: spot at apical margin of fore and middle femur, fore tibia entirely and outer part of middle tibia.

Male. Unknown.

Distribution.

North Vietnam.

Remarks.

This species comes close to Labus clypeatus van der Vecht in having the propodeum with posterior excavation not margined above, and pronotum with long and sharp projection at the lateral corners, but it is different from the latter by the female head with frontal fovea much larger than anterior ocellus, oval (head with frontal fovea small, slightly larger than anterior ocellus, round in L. clypeatus ), female clypeus with sharper teeth, and swollen part of the petiole longer than half the total length of the petiole (swollen part shorter than half the total length of the petiole in L. clypeatus ).

Etymology.

The specific name refers to the very sharp and long projecting lateral angle of the pronotum.

Figures

Figures 1 - 7. Labus angulus sp. nov., holotype, female 1 head, frontal view 2 head, dorsal-frontal view 3 mesosoma, dorsal view 4 propodeum, posterior view 5 TI, dorsal view 6 matasomal segments, lateral view 7 habitus. Scale bars: 0.5 mm.