Paleoxyela nearctica, Jouault & Aase & Nel, 2021

Jouault, Corentin, Aase, Arvid & Nel, AndrØ, 2021, Past ecosystems drive the evolution of the early diverged Symphyta (Hymenoptera: Xyelidae) since the earliest Eocene, Fossil Record 24 (2), pp. 379-393 : 381-383

Paleoxyela nearctica sp. nov.

( Figs. 1–3 )

urn:lsid:zoobank.org:act:71648E38-0501-49B6-AE0D-

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Holotype

Specimen identifier UCM 18643 housed in the collection of the Museum of Natural History (University of Colorado, USA).

Etymology

The specific epithet refers to the Nearctic origin of the fossil and is to be treated as an adjective.

Locality and age

Florissant, Colorado, Paleogene, Eocene, Chadronian.

Diagnosis

As for the genus (vide supra).

382 C. Jouault et al.: Past ecosystems drive the evolution of the early diverged Symphyta

Description

Head transverse 1.71 mm long (mandibles included) and 2.32 mm wide, vertex broadly rounded; eyes wide, occupying a large part of head lateral surface; mandibles projected anteriorly, partly covered by labrum; ocelli not preserved; four conspicuous antennomeres (apical part poorly visible and exact number not countable); scape ca. 0.50 mm long; first flagellomere ca. 3.06 mm long, slightly wider near mid-length, remaining part of flagellum ca. 0.23 mm long (maybe longer but not preserved).

Thorax slightly wider than head, pronotum (in dorsal view) short dorsomedially (ca. 0.35 mm long), slightly longer laterally, mesoscutum massive, with notauli impressed but apparently not meeting posteriorly, mesoscutellum, and remaining part of the thorax not discernable.

Forewing ca. 9.93 mm long and 3.16 mm wide. Pterostigma sclerotized, wide and longer than cell 2r; costal area not dilated proximad near Sc1 and Sc2 fork; Sc with two branches, Sc1 meeting with C far beyond Rs, subequal to Sc2; Sc2 almost vertical, meeting R near the middle of cell 1rs; Sc2 conspicuously shorter than 1-Rs, the latter subequal to 1-M; R slightly curved before origin of Rs and slightly thickened before pterostigma; costal space apically with vertical sclerotization between C with R delimited from pterostigma with costal break (membraneous slit); crossveins 1r-rs and 2r-rs, equal in length, straight or nearly so; Rs+M about 2.3 times as long as 1-Rs; section of Rs between 1r-rs and 2r-rs strongly arched toward posterior margin of forewing; cell 1rs elongate, longer than cell 3r, slightly trapezoidal; M+Cu slightly curved in its basal third; 1m-cu 0.72 times as long as 2-Cu or 3-Cu; 2m-cu straight and 0.41 times as long as 4-Cu.

Hind wing with 1r-m long, meeting Rs slightly distad its base; cell 1r thin and elongate; 1-M fully preserved, apparently shorter than 1r-m; 2r-m and 3r-m straight, both nearly equal in length; M+Cu straight; m-cu meeting 3-M in the middle of 3r; 1cu-a not fully preserved, meeting Cu in the middle of cell mcu; cell 1cua broad and long; 1A nearly straight; cell 1a elongate, rectangular; 2A complete, nearly straight.

Legs partly preserved. Hind femur ca. 3.20 mm long, slightly wider medially; hind tibia at least as long as femur.

C. Jouault et al.: Past ecosystems drive the evolution of the early diverged Symphyta 383

Abdomen with 10 visible segments, widest near mid-length, length of abdominal segments measured dorsomedially (in millimeters): 0.53, 1.02, 0.89, 0.88, 0.90, 0.82, 0.94, 0.70, 0.56 (IX and X combined). Ovipositor ca. 0.75 mm long, cercus slightly protruding from abdomen posteriorly from segment 10.

Remark

To date, there is only one Macroxyelini fossil species known from Florissant – Megaxyela petrefacta ( Brues, 1908; Zhelochovtzev and Rasnitsyn, 1972) – but the new specimen clearly differs from the latter species owing to the different configuration of the vein 1-RS and 1-M, i.e., almost equal in length (vs. 1-M much shorter than 1-RS in Megaxyela ).

Figures

Figure 1. Photograph of Paleoxyela nearctica gen. et sp. nov. Holotype UCM 18643. Scale bar: 5 mm. (' Talia Karim).

Figure 2. Paleoxyela nearctica gen. et sp. nov. Holotype UCM 18643. (A) Detailed photograph of head and thorax. (B) Detailed photograph of right wings. (C) Detailed photograph of left wings. Scale bars: 1 mm. (' Talia Karim).

Figure 3. Paleoxyela nearctica gen. et sp. nov. Holotype UCM 18643. (A) Interpretative line drawing of right wing venation with cell (in bold) and vein names labeled. (B) Interpretative line drawing of venation of left wings with cell (in bold) and vein names labeled. Scale bars: 1 mm.