Leptostigma longitenebricum, Archibald & Rasnitsyn, 2023

Archibald, S. Bruce & Rasnitsyn, Alexandr P., 2023, Cimbicidae (Hymenoptera, ‘ Symphyta’) in the Paleogene: revision, the new subfamily Cenocimbicinae, and new taxa from the Eocene Okanagan Highlands, Zootaxa 5278 (1), pp. 1-38 : 18-20

Leptostigma longitenebricum n. sp.

http://zoobank.org/ urn:lsid:zoobank.org:act:82407841-CBF9-4647-A04B-A12A242B7AE0

Figs. 3I–J , 16–18 .

Holotype. F-1565 (part, counterpart) ( Figs. 3I–J , 16 ). Almost complete, in dorsal aspect, but legs, one antenna, body mostly poorly preserved, hind wings poorly preserved; from McAbee, collector John Leahy; housed in the collections of TRU.

Diagnosis. Distinguished from other species of Leptostigma by antenna with a combination of club elongate, darker than flagellar base, base two long, pale segments; forewing lightly, evenly infuscate throughout. Tentatively diagnostic: R+M longer than 1-M, 2r-rs enters cell 3rm at or before its middle, 2r-m enters M far behind 2m-cu, anal cells separated by 1A joining 2A+3A for at least half height of cell 2a.

Description. Holotype. Body length ca. 15.5 mm, body, legs, pterostigma dark (tarsi less dark), antenna with club darkened, funicle paler, wing membrane lightly infuscate throughout. Head roundish, eyes occupying most of head sides, oval, converging ventrally, with temples weak (scarcely visible in front view), toruli close to each other. Antenna with eight antennomeres, club elongate, narrowed apically, two basal flagellar segments cylindrical, next three widened, apical one narrowed distally; basal, apical segments longest, penultimate shortest.Pronotum with wide lateral lobes; median longitudinal mesonotal sulcus, notauli well developed, meeting well before scarcely transverse scutellum; metanotum rather narrow, with wide triangular scutellum, small, roundish cenchri. Forewing length holotype 15.5 mm (F-1563, 11.5 mm), maximum width estimated 3.5–5 mm, length/width: 3.1–3.3; pterostigma narrow, tapering, similar to width of C-R before pterostigma; R+M longer than 1-M; maximum length of cell 2r shorter than 3r; 2r-rs shorter than Rs between 2r-m, 2r-rs, joining Rs at middle of cell 3rm; 2r-rm curved, sometimes slightly sigmoidal, joins Rs at or slightly distal to 2m-cu joins M, joins M behind 2m-cu more than for half length of 2r-m; 1-M curved or (GSC 142842) almost straight; cell 1mcu with M, 1m-cu slightly divergent toward anterior margin; 3r-m near straight or (GSC 142842) distinctly bowed toward base; cell 2mcu with M similar length or (GSC 142842) shorter than 1m-cu; 2m-cu slightly curved toward base; cu-a postfurcal (holotype) or interstitial; anal cell separated by 1A fusion with 2A+3A (no crossvein) for length of almost half width of cell 2a in GSC 142842, for more than its width in F-1563. Mid, hind femora long, oval, ca. 3.5 times as long as wide; tibiae thin, only slightly longer than their femora, basitarsi ca. 0.35 as long as their tibiae. First abdominal tergum if correctly identified (F-1563 only) entire, with straight hind margin.

Remarks. Differs from L. longiclava n. sp. and L. longipallidum n. sp. by flagellar base pale and, venationally, in more the distal position of 2r-rs (behind middle of cell 3rm). Differs from L. brevilatum n. sp. by its antennal club being long, also venationally by its R+M long and anal cells distinctly separated by fusion of 1A with 2A+3A. Differs from L. proxivena n. sp., L. fasciatum n. sp., L. alaemacula n. sp. with unknown antenna by its wing membrane lightly, evenly infuscate throughout (without fascia or macula) and by 2r-m entering M far behind, not close to, 2m-cu.

Material. Holotype and tentatively from venation F-1563 ( Fig. 17 ), collector unknown, in the collections of TRU, and GSC 142842 , collector SBA at McAbee ( GSC locality V-016800), July 12, 2000 ( Fig. 18 ), housed in the collections of the GSC (Vancouver).

Etymology. From the Latin longus, meaning long, and tenebricus, dark, referring to the antennal club. The epithet is an adjective.

Locality and age. McAbee, British Columbia, Canada, Hoodoo Face beds; mid-Ypresian.

Figures

FIGURE 3. Heads of Cenocimbicinae: A, Leptostigma brevilatum GSC 142839, drawing; B, L. brevilatum GSC 142839, photograph; C, Leptostigma longipallidum GSC 142841, drawing; D, L. longipallidum GSC 142841, photograph; E, Cenocimbex menatensis MNHN-LP-R.11195, drawing; F, C. menatensis MNHN-LP-R.11195, photograph; G, Leptostigma longipallidum F-771, drawing; H, L. longipallidum F-771, photograph; I, Leptostigma longitenebricum F-1565, drawing; J, L. longitenebricum F-1565, photograph; K, Leptostigma longiclava RBCM.EH2017.050.4085.0001, drawing; L, L. longiclava RBCM.EH2017.050.4085.0001, photograph. Scale bars 2 mm.

FIGURE 16. Leptostigma longitenebricum holotype F-1565, A, photograph, B–C, wing drawings: B, left forewing; C, right forewing. All to scale, 5 mm.

FIGURE 17. F-1563, tentative Leptostigma longitenebricum, A, photograph and B–C, wing drawings: B, left forewing; C, right forewing. All to scale, 5 mm.

FIGURE 18. GSC 142842, tentative Leptostigma longitenebricum forewing: A, photograph; B, drawing. Scale bar 5 mm.