Bareogonalos xibeidai Tan & van Achterberg

Tan, Jiang-Li, Achterberg, Cornelis van, Tan, Qing-Qing & Zhao, Lin-Peng, 2017, New species of Trigonalyidae (Hymenoptera) from NW China, ZooKeys 698, pp. 17-58 : 19-24

Bareogonalos xibeidai Tan & van Achterberg sp. n. Figs 1-2, 3-13, 14-22

Type material.

Holotype, ♀ (NWUX) "NW China: Shaanxi, Fengxian County, Baoji, Jialingjiang Riv[er] Source, 1513 m, 34°25'N 106°94'E, 1.ix.2016, JL. Tan & QQ. Tan, NWUX", "Reared from nest of Vespula structor (Smith)". Paratypes: 6 ♀ + 8 ♂ (NWUX, RMNH), same label data.

Diagnosis.

Left mandible with two subapical teeth, ventral tooth shorter than dorsal tooth; maxillary palp with six segments; width of head in dorsal view 1.05-1.10 times maximum width of mesoscutum (Figs 4, 15); anterior half of scutellum flat and at same level as mesoscutum; metanotum with large protuberance and long setae; wing membrane near veins 1-SR and 1-M of fore wing subhyaline as remainder of wing except darkened apical third of wing (Figs 3, 14); hind basitarsus slender (Fig. 12); fourth and fifth tergites largely smooth and shiny; third sternite of ♀ in ventral view distinctly protruding medio-posteriorly (but obscured by second sternite). Differs from the only other known Palaearctic species, B. jezoensis (Uchida) mainly by the colour of the wing membrane (largely subhyaline vs largely yellowish in B. jezoensis ; Fig. 23), the median groove of the mesoscutum (absent posteriorly vs present) and the wider head (1.05-1.10 times vs 0.80-0.90 times width of mesoscutum).

Description.

Holotype, ♀, length of body 9.2 mm (of fore wing 8.5 mm).

Head. Antenna with 20 segments, segments of apical half 1.1-1.3 times as long as wide (Fig. 13); frons and vertex smooth and strongly shiny, flat except a shallow depression behind each posterior ocellus (Figs 9, 15), with fine and long greyish setae; head gradually narrowed behind eyes and 1.05 times as wide as mesoscutum (Fig. 4); dorsal length of eye 0.9 times length of temple (Fig. 9); temple smooth and shiny; occipital carina thick and moderately lamelliform medio-dorsally and with a short crenula; supra-antennal elevations low, as a thin rim and smooth; clypeus moderately depressed medio-ventrally and flat above depression.

Mesosoma. Length of mesosoma 1.1 times its height (Fig. 5); mesopleuron below transverse mesopleural groove densely moderately reticulate-rugose, narrowly smooth posteriorly and with satin sheen, above groove coarsely reticulate; transverse mesopleural groove wide, deep and coarsely crenulate (Fig. 5); notauli medium-sized and distinctly crenulate; mesoscutum coarsely rugose-reticulate and with satin sheen contrasting with shiny head, antero-medially with parallel-sided flattened area, convex but medially slightly depressed (Fig. 4); scutellar sulcus curved, parallel-sided and coarsely crenulate; scutellum reticulate-rugose, convex and anteriorly above level of mesoscutum; metanotum medially with large and coarsely reticulate trapezoid protuberance (Figs 4, 5), apically shallowly emarginate, in lateral view not or hardly protruding over base of propodeum; propodeum largely finely reticulate-rugose, but anteriorly coarsely crenulate (Fig. 4).

Metasoma. First tergite 0.3 times as long as apically wide (of paratype, obscured by propodeum in holotype), gradually narrowed basally, flat medially and straight apically; second tergite smooth and strongly shiny as following tergites, but with lateral patch of fine punctures; second sternite rather densely finely punctate and shiny, its medio-apical protuberance densely setose and widely truncate medially (Fig. 7), protuberance of third sternite similar but smaller and obscured by second sternite in ventral view (Fig. 7); down curved apex of metasoma nearly up to protuberance of second sternite (Fig. 8).

Legs. Hind coxa and femur smooth and shiny.

Colour. Black; palpi, mandible apically, antenna (but scapus yellow ventrally and basal third of antenna brown), tegulae (but humeral plate brown), first tergite, veins (except yellowish veins 1-SR, 1-M and 1-SR+M of fore wing) and pterostigma dark brown; coxae basally black; femora (except yellow anterior face of fore femur, base and apex of middle and hind femora), and inner side of hind tibia (and partly ventrally) dark brown; 3 apical segments of hind tarsus and infuscate; pronotum dorso-apically, pair of wide patches on mesoscutum anteriorly, axilla, scutellum latero-posteriorly, dorso-apical patch of mesopleuron, pair of large antero-lateral patches on second–sixth tergites (touching each other on fourth and fifth tergites), pair of small subposterior patches on first sternite, large V-shaped patch on second sternite, and remainder of legs yellow; membrane of fore wing subhyaline, but apical 0.4 weakly infuscate (Fig. 3).

Variations. Length of body 8.0-9.3 mm, of fore wing 8.0-8.9 mm; antenna of ♀ with 20(2) or 21(2) segments; width of head in dorsal view 1.05-1.10 times maximum width of mesoscutum; mesoscutum sometimes entirely black, or with additional yellow spot medio-posteriorly; length of vein 1-M of fore wing 2.1-3.1 times as long as vein 1-SR; mandible entirely blackish brown or with some brownish patches subapically; antero-lateral yellow patches of metasoma either all separated from each other, or all touching medially, but sometimes only on second–fourth tergites being separated; yellow patch of second sternite may be separated into large patches; inner side of hind tibia largely dark brown or only apical third.

Male. Length of body 7.2-9.6 mm, of fore wing 6.8-8.0 mm; antenna with 20(4) or 21(1) segments, basal quarter of antenna black, but scapus pale yellow with upper part dark brown and pedicellus brown; mesoscutum, mesopleuron, and metasoma en tirely black or mesoscutum with pair of tiny yellow spots anteriorly and second sternite with pair of medium sized yellow spots; veins 1-SR, 1-M and 1-SR+M of fore wing dark brown. Genitalia, see Fig. 22.

Biology.

The type series was reared from a nest of Vespula structor (Smith, 1870) ( Vespidae : Vespinae).

Etymology.

Named after one of the oldest universities in China, the Northwest University in Xi’an, for providing us the facilities to research the biodiversity of Qinling Mts. It also points to the fact that this is the most north-western locality the genus is known from ( “xibei” means “northwest” in Chinese).