Xenodellitha preta, Engel, 2017

Engel, Michael S., 2017, New Evanioid Wasps from the Cenomanian of Myanmar (Hymenoptera: Othniodellithidae, Aulacidae), with a Summary of Family-Group Names among Evanioidea, American Museum Novitates 2017 (3871), pp. 1-28 : 7-10

Xenodellitha preta , new species

Figures 1–2

DIAGNOSIS: As for genus (above).

DESCRIPTION: Total length as preserved (excluding antennae, and to apparent apex of metasomal segment VI as specimen is not preserved beyond that point) 4.15 mm; forewing length 2.55 mm; integument largely dark brown (where not augmented by preservation), largely glabrous; integument without pronounced sculpturing or punctation, largely finely imbricate, except propodeum, which is coarsely and strongly areolate; wings clear and hyaline, veins brown to light brown in preserved color.

Head perhaps slightly longer than wide (directly frontal view not possible as preserved); gena narrow, tapering in width from upper to lower tangent of compound eye, narrower than compound eye, genal width at about midlength 0.18 mm; short, narrow malar space separating mandibular base from lower border of compound eye, with space much shorter than basal mandibular width; compound eye ovoid with lower border comparatively flattened, without circumocular carina, inner margins apparently slightly diverging ventrally, compound eye length 0.44 mm, width 0.29 mm (best observed on left side of head); ocelli large, arranged in small triangle on top of vertex above compound eyes and immediately before facial prominence, ocelli separated by approximately their diameter and from posterior border of head by slightly less than twice their diameter. Prominent facial horn projecting to length of 0.29 mm in profile, extending well in front of compound eyes, apex with blunt, upper transverse ridge paralleled by similar lower ridge (fig. 2B). Antennal toruli broadly separated by facial prominence, situated on lateral sloping surfaces of horn such that they open dorsolaterally and sit in front of compound eyes (fig. 2B); scape longer than wide, length about 2.6× width, length 0.26 mm, maximum width 0.10 mm; pedicel about 1.6× as long as wide; flagellomeres each longer than wide, flagellum tapering gradually in length and slightly in width toward apex; first flagellomere longest, about as long as scape. Clypeal base indistinct from frons, with distinct medial longitudinal ridge, ridge extending basally upward to lower origin of facial horn and apically projecting as small triangular prominence between mandibles (fig. 2B). Mandible large, square in frontal view, with straight outer and apical margins, margins meeting at rounded orthogonal outer angle; inner margin with at least three teeth and with one longer, pointed apical tooth (fig. 2B).

Mesosoma laterally compressed, longer than high, length 1.63 mm, maximum height 1.05 mm; pronotum prominent, with poorly defined, raised posterior surface, anterior medial surface apparently slightly longer than wide and extending forward as short neck, lateral surfaces large and slightly depressed, lateral surface with weak row of areolae bordering mesepisternum; propleura long but not projecting anterior to pronotum; mesoscutum with faint medial line and weak notauli, notauli reaching to transverse sulcus but not meeting sulcus, mesoscutal length 0.56 mm; mesoscutellum arched in profile, medial length 0.31 mm; mesopleuron with oblique depression and small, single row of weak areolae demarcating border with pronotal lateral surface, and even weaker row of areolae along border with metepisternum; metanotum subvertical, short, length 0.11 mm; propodeum coarsely and strongly areolate, with prominent dorsal surface, dorsal length (between metanotum and articulation with metasomal petiole) 0.23 mm. Legs long, with slender podites (hind legs broken at amber’s surface; not preserved beyond about basal 0.5–0.75× of metafemoral length in holotype). Forewing (fig. 2B) with costal space apically about as broad as pterostigma; pterostigma much longer than wide, tapering gradually in width in apical half to acute apex, margin inside marginal cell slightly convex; basal vein M+Cu forking distad midlength of Sc+R, 1M straight, forming faint angle at junction with 1Rs, slightly longer than 1Rs; 1Rs originating basal to pterostigma (at distance less than its length but slightly more than basal pterostigmal width); Rs+M straight, forking at about tangent with pterostigmal basal one-quarter length; 2Rs greatly longer than 2M; 2M exceedingly short and directed posteriorly to meet 1m-cu; 3M longitudinal and extending out toward wing apex; 2Rs largely straight, without kink or rudiment of crossvein; r-rs originating at about pterostigmal midlength, sinuous, elongate, about as long as 2Rs; marginal cell broad, greatest anteroposterior width near tangent of pterostigmal apex, elongate, separated from wing apex by distance less than that of length of pterostigma, with Rs (3Rs+4Rs) comparatively straight for majority of marginal cell length; two rs-m crossveins present, both distinctly weaker and thinner than surrounding veins (but not nebulous), both arched; second submarginal cell with nearly obsolescent anterior border along Rs, posterior border shorter than posterior bor- der of third submarginal cell; third submarginal cell longer than second submarginal cell; discal (discoidal) cell almost forming strongly slanted rhomboid (not distinctly pentagonal owing to exceptionally short 2M), 1m-cu straight, slightly longer than 1Cu; 1cu-a confluent with 1M; 2m-cu nebulous; 2cu-a present and demarcating subdiscal (subdiscoidal) cell. Hind wing with venation largely complete (fig. 2C) except lacking C; R with three distal hamuli, vein terminating immediately beyond hamuli, not meeting Rs apically; rs-m oblique, longer than 1Rs, much shorter than first 1M; Cu+cu-a present, nearly orthogonal to M+Cu; jugal lobe lacking.

Metasoma with first segment forming tubular petiole, petiole length 0.54 mm, narrower basally, basal width at articulation with mesosoma 0.06 mm, becoming thicker at juncture with remainder of metasoma, apical width 0.16 mm, tergum I and sternum I fused without apparent indication of individual sclerites; metasomal segments posterior to petiole not compressed laterally, roughly cylindrical (fig. 1), length as preserved 1.75 mm (metasoma is largely cleared and broken at amber’s surface), gradually and slightly tapering in height from segment II to segment VI, maximum height 0.73 mm.

HOLOTYPE: Sex uncertain, possibly male (fig. 1), AMNH Bu-096; Cretaceous amber (Cenomanian), Myanmar, Kachin, Tanai Village on Ledo road 105 km NW of Myitkyna; deposited in the Division of Invertebrate Zoology , American Museum of Natural History , New York.

ETYMOLOGY: The specific epithet is taken from the Classical Sanskrit, preta , referring to the spirit of the dead; preta s suffered from poor karma in this life, becoming bizarre and starved in the afterlife. The name is treated as a noun in apposition.

Clade Aulaciformes Grimaldi and Engel, 2005

Family Aulacidae Shuckard, 1841

Subfamily Hyptiogastritinae Engel, 2006

Hyptiogastritinae Engel, 2006: 454 . Type genus: Hyptiogastrites Cockerell, 1917a .

DIAGNOSIS: This extinct subfamily is distinguished from Aulacinae by presence of complete occipital carina, and forewing crossveins 1rs-m, 2rs-m, and 2m-cu absent.

COMMENTS: Previously the subfamily had been considered to consist of only the type genus, but it now seems apparent that the genus Protofoenus Cockerell, 1917a , also described from Burmese amber ( Cockerell, 1917a), should also be included among the Hyptiogastritinae . The discovery of a new taxon similar to Protofoenus that clearly is more properly grouped among hyptiogastritines tends to indicate that Cockerell’s genus is a basal aulacid rather than a gasteruptiid (Foeninae by his attribution 2). This was already clear from the short and broad female metasoma (elongate in Gasteruptiidae ), simple metatibia (clavate in Gasteruptiinae and Hyptiogastrinae ), nonplicate forewings (plicate at rest in Gasteruptiidae ), and comparatively straight course of 3Rs (3Rs is bent anteriorly at about midlength in Gasteruptiinae and Hyptiogastrinae ). The discal cell shifted posteriorly and below the level of M+Cu led Cockerell (1917a) to align his fossil with Gasteruption Latreille, 1796. His description, while brief, is sufficient to determine its remarkable similarity to the new species presented here, and they are both clearly aulacids. A detailed account of Hyptiogastrites electrinus Cockerell, 1917a is provided by Jennings et al. (2004).

Figures

FIGURE 1. Microphotographs of holotype (AMNH Bu-096) of Xenodellitha preta, new genus and species, in mid-Cretaceous amber from northern Myanmar (to the same scale). A. Left lateral view. B. Right lateral view.

FIGURE 2. Morphological details of holotype (AMNH Bu-096) of Xenodellitha preta, new genus and species (wings to the same scale). A. Forewing, with pertinent veins labeled. B. Head in oblique view. C. Hind wing.