Pristaulacus diffusus Long & Turrisi, 2024

Pham, Nhi Thi, Long, Khuat Dang, Dzuong, Nguyen Van, Mai, Pham Quynh & Turrisi, Giuseppe Fabrizio, 2024, The genus Pristaulacus Kieffer, 1900 (Hymenoptera: Aulacidae) in Vietnam and Northeastern Laos with descriptions of ten new species, Zootaxa 5432 (2), pp. 213-249 : 225-227

Pristaulacus diffusus Long & Turrisi , sp. nov.

Figures 7–8, 23

Type material. VIETNAM: holotype, ♀, labelled “Aulac. 012 ” ( IEBR), CH Vietnam: Kon Tum, Sa Thay, Chu Mom Ray NP, forest, 14°25’N 107°47’E, MT , 2.ii.2015, HT Phuong. Paratypes, 2♀, “Aulac. 010 ” ( IEBR), same data as holotype; “Aulac. 011 ” ( IEBR), NW Vietnam: Son La, Thuan Chau , forest, 21°19’02.2’’N 103°35’14.1’’E, 1591m, MT , 27.iv–2.v.2016 ( HTHCT) . LAOS: paratypes, 1♀, labelled “ LAO, Houaphanh Prov., Ban Saleui, Phou Pan-Mt., 20°13’30’’N 103°59’26’’E 1350–1900 m, 18.5.2011, leg. C. Holzschuh +locals” ( OLML) .

Etymology. From Latin “diffusus ” meaning “spread out, extended, dispersed”, because this species is widely distributed throughout Vietnam, i.e. from Northwestern to Central Highlands Vietnam, and extends to Northeastern Laos.

Diagnosis. Head from above 1.1 × wider than long; occipital carina lamelliform, complete, 0.6 × diameter of an ocellus median occipital margin roundly (evenly), slightly concave ( Fig. 8A); pronotum, in lateral view, with one projecting tooth-like process; scutellum almost smooth with 3 transverse striae; fore wing membrane hyaline, veins of fore wing brown with large dark substigmal spot, extending near vein 2-Ma; hind femur 0.7 × length of hind tibia; tarsal claws with four tooth-like processes; petiole slender, widened apically, 3.1 × its apical width; ovipositor 1.1 × fore wing length.

Description. (holotype, ♀), body length: 8.0 mm; antenna length: 4.2 mm; fore wing length: 6.7 mm; ovipositor length: 7.1 mm ( Fig. 7).

Colour. Head black; setae whitish; palpi blackish brown; mandible brown basally, brown apically; scape brown yellowish ventrally; pedicel and flagellomeres dark brown; mesosoma black; fore legs yellow, except fore coxa brownish yellow; middle legs yellow, except middle coxa, trochanter and third-fifth tarsus brownish yellow; hind legs dark brown; fore wing hyaline, veins of fore wing brown with large dark spot below stigma, extending near vein 2-Ma ( Fig. 8I); metasoma dark brown, except tergite 2 yellow basally; ovipositor sheath brown; ovipositor yellow.

Head. From above 1.1 × wider than long dorsally; scape 1.6 × length pedicel; first flagellomere 1.9 × as long as scape, and 0.6 × length of second flagellomere; occipital carina lamelliform, complete, weakly concave medially, 0.6 × diameter of an ocellus; POL: OOL = 15: 13 ( Fig. 8A); frons and malar space with long pubescence ( Fig. 8B); malar space punctate, with long pubescence, 0.4 × eye length; clypeus densely punctate, 3.3 × as wide as high; frons with fine dense punctures; temple roundly narrowed posteriorly, 0.9 × eye length dorsally; vertex and temple setose, with scattered fine punctures ( Fig. 8C); distance between punctures 2.0–2.5 × puncture diameter.

Mesosoma . Propleuron areolate-rugulose, pubescence long and dense, latero-ventral margin with one tooth-like process ( Fig. 8F); mesoprescutum in lateral view slightly protruding anteriorly over pronotum, with short V-shaped groove antero-medially ( Fig. 8D),lateral lobes transverse-carinate; scutellum coriaceous, with 2–3 transverse carinae; axillae areolate-rugose; metapostnotum deep, finely crenulate ( Fig. 8H); metapleuron and propodeum areolate-rugose, with short whitish pubescence; posterior-ventral margin of propodeum with dense whitish pubescence. Fore wing with veins 2-Rs curved medially; vein 2-Ma almost straight; r: 3-Rs = 11: 15; discal cell slightly narrowed anteriorly; vein 2-Rs+M long ( Fig. 8I), 2-Rs+M: 2-Ma: 3-Ma: 3-Mb = 4: 22: 6: 10 ( Fig. 8I); hind coxa slender, subapical groove (ovipositor guide) wide and deep, with sparse setae ( Fig. 7C); apical trochanteral groove wide; trochantellus distinct ( Fig. 7B); hind femur 0.7 × length of hind tibia; inner spur: outer spur = 11: 10; hind basitarsus 1.1 × length of tarsomeres 2–5 combined; hind basitarsus 3.1 × length of second tarsomere; second tarsomere 1.5 × length of third; third tarsomere 2.0 × length of fourth; fourth tarsomere 0.4 × length of fifth; tarsal claw with five tooth-like processes ( Fig. 8E).

Metasoma. Pyriform (lateral view) ( Fig. 8G), weakly compressed laterally; petiole slender, widened apically, 3.1 × its apical width; petiole shiny, smooth; tergite 2 mostly polished and shiny, with a few fine superficial rugae medially; remaining tergites with fine dense punctures and short dense setae; ovipositor 1.1 × fore wing length.

Male. Unknown.

Variation. Examined 2♀. The paratype is significantly smaller than holotype, but otherwise share almost all the diagnostic features: colour, colour pattern and structure. Body length: 6.2 mm; antenna length: 3.5 mm; fore wing length: 4.6 mm; ovipositor length: 4.9 mm. In the fore wing, there is a very narrow, obsolescent irregular brownish interstitial spot between B and D1.

Taxonomic remarks. The new species is not obviously related to any known Oriental species, and it is distinguished due to the combination of the small size, around 8.0 mm; shape of the head, width/length of head 1.1; gena length equal to dorsal eye length; setae on head and mesosoma moderately long and dense.

Biology. Unknown.

Distribution. Northwestern Vietnam (Son La province); Central Vietnam (Kon Tum province); Northeastern Laos (Houaphanh province) ( Fig. 23).