Triancyra acuta, Pham & Broad & Zhu & Achterberg, 2018

Pham, Nhi Thi, Broad, Gavin R., Zhu, Chao-Dong & Achterberg, Cornelis Van, 2018, A review of the genus Triancyra Baltazar (Ichneumonidae: Rhyssinae) from Vietnam, with descriptions of three new species, Zootaxa 4377 (4), pp. 565-574 : 566-568

Triancyra acuta sp. nov.

( Figure 1 )

Diagnosis. Ground colour black with yellow markings; distance between posterior ocelli 1.8× as long as ocellarocular distance; occipital carina largely absent dorsally; clypeus with deep transverse groove basally, apical margin with median acute point; first tergite shorter than its apical width.

Material examined. Holotype: ♀ ( RMNH), Dak Lak Province, Chu Yang Sin NP, Krong K’Mar , Malaise trap, 840–940 m a.s.l., 2–10.vi.2007, C. v. Achterberg & R. de Vries leg.

Description of female holotype. Head: antenna with 29 flagellomeres, first flagellomere 1.2× length of second; frons punctate, with shallow groove medially; face 0.7× as high as wide, with large punctures, striate medially; clypeus about 0.35× as high as wide, basally with deep transverse groove, apical margin medially pointed; malar space 0.6× as long as basal width of mandible, densely punctate, pubescent; inner margins of eyes slightly convergent medially; diameter of lateral ocellus 0.7× ocellar-ocular distance, distance between posterior ocelli 1.8× as long as ocellar-ocular distance; vertex rugose-punctate; occipital carina largely interrupted dorsally, ventrally meeting hypostomal carina about 0.9× basal mandible width from base of mandible.

Mesosoma: Epomia short; pronotum shining, impunctate, except dorsal and posterior margins with dense, fine punctures; mesoscutum 0.9× as long as wide at anterior level of tegulae, notauli present, short; scutellum densely coarsely punctate, lateral carina absent; metascutellum polished, impunctate; mesopleuron with dense punctures except impunctate speculum, epicnemial carina present on ventral 0.5 of mesopleuron; metapleuron with moderately dense, small punctures; propodeum short, with dense punctures laterally, basally with short, broad groove medially, posterior transverse carina absent medially, area petiolaris wrinkled, distance from pleural carina to propodeal spiracle about 0.9× as long as length of spiracle; mid basitarsus 1.6× second tarsomere; hind leg with femur 5.3× as long as wide, 0.8× length of tibia, tarsus equal to tibia length, basitarsus 1.6× second tarsomere, fifth tarsomere 1.4× longer than third, 0.8× second. Fore wing length 11.2 mm, vein Rs&M slightly distad of cu-a, vein 2 rs-m basad of 2 m-cu by about 0.25× length of 2 rs-m, hind wing with first abscissa of vein Cu 1 nearly fused with M.

Metasoma: first tergite 0.8× as long as apical width, with dense, fine punctures except smooth and polished posterior band; second tergite 1.4× as long as first tergite, densely finely punctate; third tergite onwards with dense, coarse punctures; ovipositor sheath about 4.3× length of hind tibia, 1.4× length of fore wing, lower valve with nine apical teeth, upper valve with six.

Colour. ground colour black with yellow marks; antenna black; face yellow with black mark connecting black clypeus to black frons medially; black occipital area connecting to black vertex; mandibular teeth and malar space black; pronotum black except antero-ventral margin, dorsal margin laterally and medio-anteriorly yellow; mesoscutum black except roughly heart-shaped yellow mark medially; scutellum black with two lateral yellow marks; metascutellum black; mesopleuron with antero-dorsal, postero-dorsal and postero-ventral yellow marks; mesosternum entirely black; metapleuron yellow except black surrounding margins; propodeum yellow, black basally and area petiolaris black; tergites 1–2 black with yellow subapical transverse bands; yellow subapical band on tergite 3 narrowly interrupted medially; yellow subapical bands gradually more broadly interrupted medially on successive tergites; fore leg with posterior side of coxa black basally, mid leg with posterior face and apical ring of coxa, basal half of trochanter and tarsus black; hind leg with coxa and trochanter black except dorsal face, trochantellus and femur ferruginous, tibia, except subbasally, and tarsus black.

Male. Unknown.

Comparison. The new species can be recognized from its congeners by the shape of the clypeus which has a deep groove basally and a median apical point ( Figure 1b ). In general coloration, the new species is most similar to Triancyra striatiscutellaris (Uchida, 1956) . It differs from the latter by the densely (finely to coarsely) punctate metasomal tergites whereas the metasomal tergites are smooth to finely punctate anteriorly in T. striatiscutellaris . In addition, the colour pattern of the mesopleuron, scutellum and metascutellum is somewhat different.

Etymology. The new species is named after its pointed apical margin of the clypeus.

Distribution. Currently known only from the type locality.

Ecological notes. The single specimen was collected in evergreen forest at an elevation of 840–940 m a.s.l.

Figures

FIGURE1. Triancyra acutasp.nov. (Holotypefemale):a. lateral view; b. face; c. tergites 1–3;d.dorsal view of scutellumand propodeum.