Triancyra mystaxa, 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 : 570-573

Triancyra mystaxa sp. nov.

( Figure 5 )

Diagnosis. Ground colour yellow with numerous black marks; occipital carina complete; distance between posterior ocelli 1.9× as long as ocellar-ocular distance; mesosoma covered with whitish setae; tergites 1–3 smooth and polished, with punctures restricted to tergite 3 anteriorly.

Description of female holotype. Head: antenna with 29 flagellomeres, first flagellomere 1.2× length of second; frons with shallow groove medially, with triangular tubercle in front of median ocellus, laterally with sparse punctures; face 0.8× as high as wide, striate and coarsely punctate; clypeus about 0.6× as high as wide, apical margin truncate; malar space 0.6× longer than basal width of mandible, smooth and subpolished; inner margins of eyes slightly convergent medially; diameter of lateral ocellus 0.6× ocellar-ocular distance, distance between ocelli 1.9× as long as ocellar-ocular distance; vertex with small punctures; occipital carina evenly curved, complete, ventrally meeting hypostomal carina about 0.5× basal mandible width from base of mandible.

Mesosoma. Epomia present, short; pronotum polished, with dense, small punctures along dorsal and posterior margins; mesoscutum 0.9× as long as wide at anterior level of tegulae, notauli present, short; scutellum with transverse striations, lateral carina absent; metascutellum polished, impunctate; mesopleuron with dense, small punctures anteriorly and ventrally, medially with transverse wrinkles, epicnemial carina present on ventral 0.5 of mesopleuron; metapleuron with moderately dense, moderate-sized punctures; propodeum with moderately dense punctures laterally, smooth and polished dorsally, without groove median dorsally, posterior transverse carina present, distance from pleural carina to propodeal spiracle about 0.25× as long as length of spiracle; fore basitarsus 1.5× second tarsomere; mid basitarsus 1.5× 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, 1.0× second. Fore wing length 9.8 mm, vein Rs&M opposite cu-a, vein 2 rs-m basad of 2 m-cu by about 0.5× length of 2 rs-m, hind wing with first abscissa of vein Cu 1 about 0.15× length of vein cu-a.

Metasoma. First tergite 1.3× as long as posterior width, smooth and polished, impunctate; second tergite 1.1× as long as first tergite, impunctate; third tergite with small punctures medially, anteriorly; tergite 4 onwards with punctures and wrinkles on anterior 0.45–0.55, rest smooth & polished; ovipositor sheath about 4.4× length of hind tibia, 1.3× length of fore wing, lower ovipositor valve with 10 apical teeth, upper valve with 5.

Colour. Ground colour yellow with numerous black marks: antenna; elongate oval spot on face connecting to black mark on frons and vertex; occipital area black, connecting to black vertex; clypeus, mandibular teeth and malar space black; pronotum ventrally (except antero-ventral margin), and a medio-dorsal spot, black; mesoscutum black except sub-rectangular longitudinal yellow mark medially; metascutellum black; mesopleuron with anterior and posterior margins and an oblique median mark black; mesosternum and metapleuron entirely black; propodeum black anteriorly and on area petiolaris; tergite 1 black on anterior 0.6, tergite 2 anteriorly with black band laterally extending nearly to posterior black band, resulting in a moustache-shaped yellow band medially; anterior and posterior reddish brown bands on tergite 3 both widened laterally and connecting to each other by a median bridge; tergites 4–6 each with a lozenge; shaped black median mark and narrow posterior black band; tergite 7 with sub-triangular median black mark and two semicircular black spots laterally; fore leg with coxa black posteriorly, fifth tarsomere black, mid leg with coxa, except dorsal face, and fifth tarsomere black; hind leg with coxa, except dorsal face, trochantellus, proximal and distal parts of tibia and tarsus black.

Male. Antenna with 26 flagellomeres, distally slightly widened; body slender but general colour pattern similar to female, tergites 3 onwards black, each tergite with two yellow marks laterally.

Comparison. In Kamath & Gupta (1972), the new species runs to couplet 10. It is most similar to Triancyra sarojinae Kamath & Gupta, 1972 in general colour pattern but differs from the latter as tergites 4–5 are punctate and wrinkled on the anterior 0.45–0.55, otherwise smooth and polished, whereas tergites 4–5 are entirely coarsely punctate in T. sarojinae . In addition, the new species has black clypeus and black metapleuron (vs. yellow in that of T. sarojinae ), largely yellow propodeum (vs. entirely black in T. sarojinae ) and the coloration of metasomal tergites 3–5 also differs from the latter. The new species differs from Trancyra lieftincki Kamath & Gupta, 1972 by the punctation of the metasomal tergites, with tergite 3 punctate anteriorly, medially (entirely smooth in T. lieftincki ) and more extensive punctation of tergites 4–5 (punctate on anterior 0.45–0.55 vs anterior 0.2–0.3 in T. lieftincki ) and the colour of the clypeus, mesosternum and metapleuron (black vs. yellow in T. lieftincki ).

Etymology. The new species is named after the moustache-shaped yellow mark on the second metasomal tergite.

Distribution. This new species is currently known only from Dak Lak Province, in the Central Highlands of Vietnam.

Ecological notes. Collected in evergreen forest.

Material examined. Holotype: ♀ ( IEBR), Dak Lak, Ea So NR, 12055’93N 108037’964E, 310 m a.s.l., H. T. Ngo leg . Paratypes: 1♀ (RMNH), 4 ♂ ( IEBR), same data as holotype .

Figures

FIGURE 5. Triancyra mystaxa sp. nov. (Holotype female): a. dorsal view; b. posterior view of head; c. face; d. lateral view of head & mesosoma; e. tergites 1–3; f. tergites 4–6.