Astymachus eximius Hayat

Hayat, Mohammad & Veenakumari, Kamalanathan, 2015, Description of four new species of brachypterous Encyrtidae (Hymenoptera: Chalcidoidea) from India, Zootaxa 3990 (2), pp. 259-271 : 260-263

1. Astymachus eximius Hayat , sp. nov.

(Figs 1–10)

Body colour was noted from card mounted specimens. After clearing and mounting on slides in Canada balsam, the brown or pale brown colour has faded.

Female. Holotype. Length (from slide), 1.27 mm. Head pale yellow; frontovertex, in card mounted specimen, with two broad longitudinal pale brown bands; occiput and malar space pale brown. Antenna with scape yellow; pedicel yellow, upper surface brown; funicle yellow to pale brownish yellow; clava brown. Mesosoma yellow; mesoscutum and scutellum each with two pale brown diffuse bands. Fore wing rudiment infuscate (Fig. 5); hind wing hyaline. Legs yellow. Metasoma yellow; TI–TV each with a narrow, pale brown cross-band (Fig. 1); exserted part of ovipositor sheaths dark brown.

Head ( Fig. 9 ) dorsal width 1.75× as broad as median length; frontovertex width 0.5× head width; vertex with 3 longitudinal pale lines/grooves, meeting in front of anterior ocellus; ocellar triangle with apical angle acute; AOL 1.36× POL; OOL 0.5× POL, and 2.2× OCL; head, in frontal view ( Fig. 10 ), with a slightly curved groove connecting toruli, and 3 grooves—one median and two lateral, with each lateral groove extending from mouth margin and ending below torulus; inter-torular distance slightly greater than torulus mouth-margin distance; head dorsum and face with fine reticulation ( Figs 9, 10 ); setae short, hyaline, except a longer seta on each side between eye margin and posterior ocellus; eye setose, setae hyaline, and each seta shorter than a facet; occiput with setae on each side of foramen ( Fig. 9 ). Maxillary palp 3-segmented, labial palp 2-segmented ( Fig. 10 ). Antenna (Figs 1, 4) with scape 3.8× as long as broad; pedicel slightly more than 0.5× scape length, and slightly longer than F1–F3 combined; funicle segments all transverse; F1 longer ventrally than dorsally, and narrower (0.87×) than F2; F2–F5 subequal in length, and 1.9× to 2.2× as broad as long; F6 large, 2.18× as long as F5, and 1.41× as broad as long; clava about 2× as long as broad, slightly longer than preceding five segments combined; clava with a single, very fine, incomplete suture. Relative measurements (holotype, slide at 100×)—head dorsal width, 28; head dorsal length (excluding upper occiput which is seen in slide mount), 16; frontovertex width, 14; antennal scape length, 9.5.

Mesosoma (Figs 2, 3). Pronotum long, 1.23× as long as mesoscutum and 2.29× as broad as long; mesoscutum 3.16× as broad as long; scutellum 1.58× as broad as long, without circular sensilla (one circular sensillum in one paratype); sculpture and setation as in Fig. 2; mesoscutum with 16 setae; scutellum with 13 setae; propodeum medially very narrow, about one-tenth scutellum length, but laterally expanded; propodeal spiracle equidistant from both margins. Fore wing (Fig. 5) extending to about basal third of TI of gaster; right fore wing 2.43× and left fore wing (Fig. 5) 2.3× as long as broad; hind wing (Fig. 6) 3.18× as long as broad, and 0.55× right fore wing length. Mid tibia 4× as long as mid basitarsus. Relative measurements (holotype)—(at 100×) mesosoma length, 27. (at 400×) pronotum length (width), 37 (85); mesoscutum length (width), 30 (95); scutellum length (width), 31 (49); propodeum median length, 3; mid tibia length, 67; mid basitarsus length, 17; mid tibial spur length, 16.

Metasoma (Fig. 1), on slide, 2.85× as long as mesosoma; exserted part of ovipositor 0.17× metasoma length; petiole large, rectangular, located in space between lateral expanded parts of propodeum (Fig. 3); second valvifer 1.34× as long as third valvula. [Ovipositor 2.97× as long as mid tibia.]

Variation. The three paratypes show some variation in the number of setae on the mesoscutum and scutellum, length and width of the fore wing and hind wing, relative lengths of the ovipositor (= second valvifer plus third valvula) and mid tibia, and the relative lengths of the second valvifer and third valvula. The body length in the three paratypes are: 1.15 mm, 1.23 mm, and 1.3 mm. The setae on mesoscutum and scutellum in two paratypes (the third paratype is mounted with the venter facing upwards, and hence not possible to count the setae) are 16 and 21 on mesoscutum, and 14 and 18 on scutellum. In one paratype (slide, EH.1799) the fore wing extends to about basal half of TII of gaster and is of a different shape and venation (Fig. 7) from that of the holotype; the right fore wing 2.61× (Fig. 7) and left fore wing 2.77× as long as broad; right hind wing 5.16× (Fig. 8) and left hind wing 4.75× as long as broad. The ovipositor in the three paratypes is 2.76×, 2.86× and 3.06× as long as mid tibia; and second valvifer 1.28×, 1.42× and 1.5× as long as third valvula.

Male. Unknown.

Material examined. Holotype, ♀ (on slide under 2 coverslips, slide No. EH.1801), labelled “ INDIA: KARNATAKA: Chikkaballapur, Nandi Hills, 27.xii.2014 (YPT), Coll. K. Veenakumari” ( NBAIR, registration No. ICAR / NBAIR /EN.39)

Paratypes: 3 ♀ (on 3 slides, Nos. EH.1799, EH.1800, EH.1802), with data same as holotype. (1 ♀, slide EH.1800, in NBAIR, registration No. ICAR / NBAIR /EN.40; 2 ♀, in ZDAMU, registration No. HYM. CH.721).

Distribution. India: Karnataka.

Etymology. Latin, eximius = uncommon, exceptional; and refers to the uncommon occurrence of brachyptery in this genus.

Comments. This is the first record of a brachypterous species in Astymachus Howard. The new species differs from all the five known macropterous species, not only in having very short wings, but also in having the maxillary palp 3-segmented, and labial palp 2-segmented, and in the presence of 5 brown cross-bands on tergites 1–5 of the gaster. The gaster is yellow or with various brown suffusions but without any brown cross-bands, and the palp formula is either 4–3 or 4– 2 in the macropterous species (see Trjapitzin 1962; Prinsloo 1989; Sugonyaev 1996; Singh & Hayat 2005). The figure given by Hayat (2006: fig. 347) is that of a labial palp of A. felix Singh & Hayat , not of the maxillary palp.

Figures

FIGURES 9, 10. Astymachus eximius Hayat, sp. nov. Female: 9, head dorsal view, holotype; 10, head frontal view, paratype (slide, No. EH. 1802).