Leptostigma brevilatum, 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 : 8-13

Leptostigma brevilatum n. sp.

http://zoobank.org/ urn:lsid:zoobank.org:act:B29C5890-4E50-4408-8D67-0E073DB25546

Figs. 3A–B , 5–10 .

Holotype. GSC 142839 ( Fig. 3A–B , 5 ). Head with antennae (one incomplete), thorax, perhaps part of abdomen, parts of several legs, both forewings, both hind wings poorly preserved, collector SBA at McAbee ( GSC locality V-016800), pre-1999, housed in the collections of the GSC (Vancouver).

Diagnosis. Distinguished from other species of Leptostigma by a combination of antenna dark, with club short and wide, with two basal flagellar segments comparatively short (combined shorter than half head width). Forewing lightly, evenly infuscate throughout. Tentatively diagnostic: R+M shorter than 1-M, 2r-rs enter cell 3rm at or before its middle, 2r-m enters M far behind 2m-cu, anal cells meet at crossvein or at most minimally separated by short fusion of 1A with 2A+3A.

Description. Holotype. Body length not known by preservation. Body as preserved (including head with antenna, thorax, femora, tibiae, abdominal base) and pterostigma dark, membrane lightly infuscate throughout, tarsal fragments (at least hind tarsomeres 1–3) darkened. Head (interpretation tentative by imperfect preservation) wider than long, with compound eyes oval, rather short, converging below, rather close to mandibles; ocelli not known, toruli close to each other, touching clypeus; clypeus small, excised apically; labrum oval, narrower and slightly shorter than clypeus; temples not inflated, scarcely exceeding eye contour.Antenna apparently with 9 antennomeres; scape, pedicel small, poorly preserved; flagellomeres possibly gradually becoming shorter, wider (but precise length sometimes obscure) except apical two of similar length; club somewhat unclear, apparently 3-segmented, short, rounded apically. Thorax poorly known by preservation, with notauli and median longitudinal mesonotal sulcus distinct, meeting well before transverse scutellum. Forewing length 13 (holotype)– 17 mm, maximum width 4–5 mm, length/width: 3.1–3.3. Pterostigma narrow, similar to width of C-R; R+M shorter than 1-M; 2r-rs before middle of cell 3rm (near middle in UWBM 54840); 2r-rm distinctly curved (F-1182 with aberrant short stub near middle in both wings), joins Rs about same level as 2m-cu joining M, joining M behind 2m-cu for more than half of 2r-m length (in F-1182, slightly less than that in right wing); 1-M straight or almost so; 3r-m almost straight; cell 1mcu with M and 1m-cu distinctly to slightly (in GSC 142840) diverging toward anterior margin, aberrant (split) in left wing of F-1182; cell 2mcu with M usually shorter than 1m-cu (as long as that in GSC 142840, slightly longer than that in F-1182); 2m-cu curved distinctly toward base (weakly so in GSC 142840); cu-a distinctly postfurcal; anal cells meet at crossvein. Hind wing with 3r-m, m-cu, cu-a present, 3r-m slightly more than its own length from m-cu; cu-a before middle of cell mcu, more than for its length before m-cu (aberrantly two cu-a present in holotype placed before and behind middle of cell mcu: which is true crossvein unclear). Legs long, narrow, hind femur widest subbasally, 2.9 times as long as wide, with lower margin smooth, hind tibia ca. 6 times as long as wide apically, hind apical spur long (as long as basitarsus, almost 0.4 times as long as tibia, Fig 9B ), sharp, tarsomere 1–3 length ratio 1: 0.7: 0.45 (in GSC 142840, femora, tibiae apparently narrower, but difficult to measure), with claw apparently simple.

Remarks. L. brevilatum n. sp. differs from all congeners with known antenna ( L. longiclava n. sp., L. longipallidum n. sp., L. longitenebricum n. sp.) by its short and wide club. It additionally differs venationally from L. longiclava n. sp. in having 2r-rs at or before middle of cell 3rm, from L. longipallidum n. sp., as well as from L. longitenebricum n. sp. in having R+M shorter than 1-M and by its anal cells being either separated by a short crossvein or at most by 1A and 2A+3A fused for a very short distance. Differs from L. proxrvena n. sp., L. fasciatum n. sp., L. alaemacula n. sp. with unknown antenna in having wing membrane lightly, evenly infuscate throughout (neither fascia nor macula) and 2r-m entering M far behind, not close to, 2m-cu.

Material. Holotype and tentatively (by venational characters) specimens F-1182/1183 ( Fig.6 ), unknown collector at McAbee, in the collections of TRU; UWBM- 54840 ( Fig. 7 ) ( Lewis 1992: Fig. 2N as unknown Hymenoptera ), unknown collector at Republic, in the collections of the UWBM; RBCM.EH2017.050.4628 ( Fig. 8 ), collector John Leahy at McAbee, in the collections of the RBCM; F-774 ( Fig. 9 ), unknown collector at McAbee, in the collections of TRU. GSC 142840 ( Fig. 10 ), collector John Leahy at McAbee ( GSC locality V-016800), in the collections of the GSC; this specimen is very tentatively attributed to the species, as it is missing 3r-m, which prevents identification of the precise position of 2r-rs with respect to cell 3rm: 2r-rs is distant from 2r-m for less that its own length, more consistent with L. brevilatum n. sp. than L. longiclava n. sp.

Etymology. From the Latin brevis, meaning short and latus, wide, referring to the antennal club. The epithet is an adjective.

Locality and age. Republic, Washington, United States of America, Tom Thumb Tuff Member of the Klondike Mountain Formation exposureA0307;and McAbee, British Columbia, Canada,Hoodoo Face beds;both mid-Ypresian.

Figures

FIGURE 2. Cenocimbex menatensis Nel, holotype MNHN-LP-R.11195: A, extract from a reflectance transformation imaging (RTI) file (Cultural Heritage Imaging 2012); B, drawing of left forewing; C, drawing of right forewing preserved portion; D, left hind wing. Scale bars 5 mm.

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 5. Leptostigma brevilatum, holotype GSC 142839. A, photograph, and B–D, drawings: B, right forewing; C, left forewing; D, right hind wing. All to scale, 5 mm.

FIGURE 6. F-1182, tentative Leptostigma brevilatum, A, photograph, and B–E, drawings of: B, left forewing; C, right forewing; D, left hindwing, and; E, right hind wing. All to scale, 5 mm.

FIGURE 7. UWBM-54840, tentative Leptostigma brevilatum: A, photograph; B, drawing from part and counterpart. Scale bar 5 mm.

FIGURE 8. RBCM-EH2017-050-4628-001, tentative Leptostigma brevilatum, A, photograph, and B–C, drawings of the wings: B, right forewing; C, right hindwing.All to scale, 5 mm.

FIGURE 9. F-774, tentative Leptostigma brevilatum:A–B photographs and C–D, wing drawings:A, the whole fossil; B, closeup with arrow indicating the hind apical spur; C, right forewing; D, left forewing.A, C–D to 5 mm scale; B scale is 2 mm.

FIGURE 10. GSC 142840, tentative Leptostigma brevilatum: A, photograph, B, drawing of the forewing; scale is 5 mm.