Trichelyon Ortega-Blanco & Engel, 2012

Ortega-Blanco, Jaime, Singh, Hukam & Engel, Michael S., 2012, First amber fossil Rhysipolini (Hymenoptera: Braconidae): a new genus and species in Early Eocene Cambay amber, Acta Entomologica Musei Nationalis Pragae 52 (2), pp. 585-594 : 588-591

Trichelyon Ortega-Blanco & Engel , gen. nov.

Type species. Trichelyon tadkeshwarense Ortega-Blanco & Engel , sp. nov.

Diagnosis. Cyclostome wasps with 26 antennomeres, antenna much longer than forewing; scape relatively robust, about twice as long as wide, pedicel about 0.75× scape length. Malar suture apparently absent (difficult to discern though). Clypeus concave, not protruding outward in profile; labrum set in ovoid hypoclypeal depression. Maxillary palpus 6-segmented. Compound eyes large, not emarginate. Occipital carina complete. Pronope absent. Notauli short, distinct only in anterior part of mesoscutum, shallow and faint from midpoint posteriorly. Epicnemial carina present. Sternaulus apparently absent. Forewing 2a vein absent; 1Rs long, more than one-half length 1M; vein 1r-rs arising just distad middle of pterostigma; 1cu-a postfurcal; 1rs-m sclerotized but faintly pigmented ( Fig. 1 ); distal abscissa M sclerotized at base then becoming nebulous; 3Rs shorter than 2M, making second submarginal cell narrower anteriorly. Metatibia without fringe stiff setae or spines on inner apex; metatibial spurs slightly curved; pretarsal claws simple, with basal area swollen; arolium large. Propodeum with small, medial areola, anteriorly integument smooth. First metasomal tergum with exceedingly faint dorsope, apparently acarinate; integument of first through third terga longitudinally striate except apical half of third tergum apparently imbricate; remaining terga largely membranous. Ovipositor sheaths slightly shorter than metatibia, asetose; ovipositor relatively straight.

Etymology. The new genus-group name is a combination of the Greek words trion (“three”) and chelyon (“tortoise shell”), and is a reference to the three-segmented carapace of the metasoma. The name is neuter.

Trichelyon tadkeshwarense Ortega-Blanco & Engel , sp. nov. ( Figs. 1–2 ) Type material. HOLOTYPE: ♀, Tad-420, India: Gujarat, Tarkeshwar lignite mine, Cambay Formation (Palaeo-Eocene),

21°21.400’N, 73°4.532’E, 11–16 January 2012; deposited in the Birbal Sahni Institute of Paleobotany , Lucknow, India. PARATYPE: 1 ♀, same amber piece as holotype and same repository .

Diagnosis. As for the genus (see above).

Description. Female. Body length 1.98 mm; forewing length 1.8 mm. Head hypognathous, covered by scattered, thin setae, most numerous in and around hypoclypeal depression; occipital carina present but low, ventrally running to base of mandibles. Compound eyes large, occupying entire lateral side of head, not emarginate. Ocelli present but difficult to discern as preserved (portions of head collapsed and fractures prevent a clear view), but distinctly far from occipital carina. Clypeus mid-ventral margin apparently placed well above level of mandibular base, with a distinct hypoclypeal depression (cyclostome). Mandibles curved inwards, facing each other, overlapping when closed, with two teeth. Maxillary palpus 6- segmented; palpomeres 3 and 4 distinctly longer than palpomeres 1, 2, 5, and 6. Labial palpus not discernible as preserved. Antenna 26-segmented, with flagellomeres cylindrical and not flattened; toruli facing upwards, inserted in a low frontal shelf; scape short and robust, about twice as long as apically wide; pedicel shorter than scape, about as wide as long; flagellomeres 1–3 longest, about three times longer than wide; flagellomeres 4 and 5 slightly longer than succeeding flagellomeres; flagellomeres 6–24 less than two times as long as wide; all flagellomeres sparsely covered with minute setae, with at least two apical, longer setae; last flagellomere tapered but with distinct elongate thin tip.

Mesosoma moderately high, not setose. Pronotum dorsally short but distinct. Posterior flange of propleuron present, placed more posteriorly than in dorsal position. Epicnemial carina present. Notauli faintly present, anteriorly more distinct. Mesoscutellum small, rhomboid. Metanotum much wider than long, almost obscured. Propodeum without spines or protuberances, with a long median carina and a small medial areola, anteriorly integument smooth. Legs with numerous setae; metacoxa elongate, slightly flattened, antero-marginally rounded (without angle or tubercle); trochanter short and flattened; trochantellus small and rounded; femora and tibiae slightly flattened; tibiae noticeably more setose, with a longitudinal row of stiffer setae or spicules along anterior surface; tibial spur formula 1-2-2; calcar simple, curved inwards, without inner lamella; remaining spurs slightly curved outward; basitarsi densely setose, with a longitudinal row of stiffened setae, slightly shorter than remainder of tarsus; last tarsomere (telotarsus) not enlarged, with length similar to individual lengths of tarsomeres 2–4; pretarsal claws simple, with basal area swollen; arolium large but not surpassing pretarsal claws in length. Forewing membrane with sparse microtrichia, more distinct and slightly thicker on margins, particularly anterior margin; pterostigma large and semioval; tubular veins include C+Sc+R, R beyond pterostigma; all abscissae Rs; M+Cu, 1M, 2M, base of distal abscissa M, all abscissae Rs+M, Cu, 1rs-m, 1m-cu, 1cu-a, and 2cu-a ( Fig. 2C ); hind wing with three hamuli, a single closed cell ( Fig. 2C ).

Metasoma about as long as remainder of body, proximally constrained, without petiole, with eight visible terga, overall largely membranous except first three terga which are heavily sclerotized and fused to form metasomal carapace; first metasomal segment proximally constrained, apparently without medial longitudinal carina, basal carinae, or distinct lateral carinae, apparently though with faint dorsope; spiracles not visible given preservation; terga of carapace with longitudinal striae except apically on third tergum imbricate; second metasomal tergum without smooth, triangular, mediobasal area; terga laterally short such that sterna are well visible laterally. Ovipositor and valves exposed, shorter than metatibia.

Etymology. The specific epithet refers to the lignite mine in Gujarat, India and from where the amber bearing the type material was collected.

Comments. As noted, where known, species of Rhysipolini are parasitoids of leaf-mining Lepidoptera. In connection with this there are small, unidentified Lepidoptera occurring in Cambay amber (D. A. Grimaldi, pers. comm.), which might have served as potential hosts. However, leaf-mining Lepidoptera extend back to the Jurassic ( GRIMALDI & ENGEL 2005) and suitable hosts were clearly abundant during the time of this fossil species.

Figures

Fig. 1. Photomicrographs of holotype (A) and paratype (B) females of Trichelyon tadkeshwarense Ortega-Blanco & Engel, gen. & sp. nov. (Tad-420) in Early Eocene Cambay amber.

Fig.2. Camera lucida drawings of Trichelyon tadkeshwarense Ortega-Blanco & Engel, gen.& sp. nov.showing important diagnostic characters. A – lateral habitus of holotype showing propleural flange, epicnemial carina, propodeum areola, and metasomal carapace, among other characters. B – apicalmost part of antennae showing prominent acute tip of last flagellomere (most easily visible in holotype).C – forewing of holotype and hind wing of paratype, showing pattern of venation. D – hind leg of paratype showing apical part of metatibia and spurs, and metatarsus with telotarsus not enlarged. E – protibia without pegs or spines (as viewed from holotype). C, D, E to the same scale.