Stigmus fronticoncavus Bashir & Ma

Bashir, Nawaz Haider, Li, Qiang & Ma, Li, 2019, Review of the genus Stigmus Panzer (Hymenoptera, Crabronidae) in China, with description of five new species from the Oriental and Palearctic Regions, ZooKeys 843, pp. 51-69 : 60-61

Stigmus fronticoncavus Bashir & Ma sp. n. Figs 3, 6d

Type material.

Holotype ♀, China: Yunnan: Ruili: Mengxiu, 24°05'N, 97°47'E, 2.V.1981, coll. Fasheng Li (CAU).

Diagnosis.

Similar to S. murotai (Tsuneki, 1977) but differ by clypeus impunctate; free margin of clypeus not produced, with two small teeth medially, nearly truncate apically; labrum five lobed; ventral surface of petiole smooth, without carina; gena impunctate; parapsidal line weakly impressed; pygidial area broadened triangular shaped. S. murotai has the following characters: clypeus with sparse, fine punctures; free margin of clypeus narrowly produced, with two triangular teeth medially, slightly emarginated in middle; labrum trapeziform; ventral surface of petiole with dense, sturdy, short, longitudinal carinae posteriorly; gena with fine punctures; parapsidal line distinct; pygidial area broadened U-shaped.

Description.

Female (Figs 3, 6d):

Measurements. BL: 5.3 mm; HW: HLD: HLF = 81: 53: 53; HW: EWd: EW: TW: EL = 81: 22: 23: 28: 50; length of scape: length of pedicel: length of flagellomere I: width of flagellomere I: length of flagellomere II: width of flagellomere II = 28: 8: 8: 3.5: 9: 4; PL: PW: LTI: WTI = 34: 8: 40: 43.

Colour pattern. Clypeus dark brown apically; mandible yellowish except reddish brown apically; labrum, palpi, scape, tegula and pedicel fulvous; flagellomere I–VI segments fulvous, VII-X reddish brown to dark brown; pronotal lobe yellowish; forewing veins brown; legs fulvous except coxa dark brown basally; petiole black; metasoma black, last segment dark brown; setae on clypeus and mandible golden.

Head. Mandible tridentate apically (Fig. 3a), median tooth larger, outer margin of mandible with a broad triangular tooth nearly apical area (Fig. 3b). Labrum with five lobes, apex with two lateral teeth and round teeth medially (Fig. 3a). Clypeus shiny, impunctate, fairly deeply impressed, setae on clypeus sparse, long; free margin of clypeus not produced, nearly truncate apically, and with two small teeth medially and two blunt teeth laterally, median teeth slightly reflected (Fig. 3a). Scapal hollow shiny, fairly deep and broad, not well outlined, provided with a small round tubercle medially, not spined. Frontal furrow lacking. Median and upper frons shiny, impunctate. Ocellar triangle area flat, shiny, impunctate, near eyes area with 3 or 4 short impressed lines, opaque area small. Vertex behind ocelli shiny, impunctate; gena shiny, smooth and impunctate (Fig. 3c). Head from above with temples somewhat roundly convergent posteriorly. Occipital carina incomplete, not ending in hypostomal carina, suddenly ended at the posterior ridge of stomal hollow, forming a blunt tooth, much narrowed, not crenulate. Inner orbital furrow broad, shiny, with inner marginal carina distinct; outer orbital furrow lacking.

Mesosoma. Anterior and lateral areas of pronotal collar with strong carinae, forming blunt angle at antero-lateral corner (Fig. 3d). Mesoscutum shiny, with tiny sparse punctures. Admedian line weakly impressed, extending to half of scutum. Prescutal sutures shallowly grooved and crenulate, reaching only anterior of scutum; parapsidal line weakly impressed. Scutellum shiny, with fine sparse punctures. Metanotum slenderly rugulose. Mesopleuron with dense sparse punctures, posterior mesopleuron shiny, with several short, slender, longitudinal rugae, episcrobal area with sparse, irregular, longitudinal rugae, scrobal suture, omaulus and hypersternaulus broadened, distinctly crenate, scrobal suture complete. Propodeal enclosure triangular medially (Fig. 3e), with a sturdy longitudinal median carina and sparse transvers rugae, with sparse sturdy oblique longitudinal rugae laterally; posterior surface of propodeum with sparse irregular rugae, forming several smooth areas (Fig. 3e); lateral surface of propodeum with sparse, sturdy, oblique longitudinal rugae.

Legs. Normal, outer surface of hind tibia with three long, slender, fulvous to dark brown, spines.

Wings. Forewing venation typical for genus Stigmus , hindwing media diverging before cu-a.

Metasoma. Dorsal surface of petiole subquadrate (cross section), slightly convex and widened toward apex distinctly, basal half of petiole with two sturdy lateral carinae and dense irregular rugae, apex with dense, sturdy, longitudinal carinae posteriorly (Fig. 3f); lateral surface of petiole with a few strong, longitudinal carinae medially and posteriorly (Fig. 3g); ventral surface of petiole shiny, smooth, without carina. Metasomal segments shiny, nearly impunctate, gastral sternum VI with fine or coarse punctures, half mat; pygidial area shiny, broadly triangular, smooth (Fig. 3h).

Male. Unknown.

Distribution.

China (Yunnan).

Etymology.

The name, fronticoncavus, is derived from the Latin front- (= frons) and the Latin word concavus (= concave), referring to the hollow, deep and broad scapal.