Urocerus ligniticus ( Piton, 1940 )

Wedmann, Sonja, Pouillon, Jean-Marc & Nel, André, 2014, New Palaeogene horntail wasps (Hymenoptera, Siricidae) and a discussion of their fossil record, Zootaxa 3869 (1), pp. 33-43 : 37

Urocerus ligniticus ( Piton, 1940)

( Figs. 4 , 5 )

Material. Holotype R. 0 7004, other specimens R. 0 7722, B. 47308, all in collection of Palaeontology department, MNHN, Paris (isolated forewings). New specimen JMP-Menat-801 (stored in the Entomology department, MNHN, Paris).

Age and outcrop. Palaeocene, spongo-diatomite maar Palaeolake, Menat, Puy-de-Dôme, France.

Description of the new specimen JMP-Menat-801. Imprint and counterimprint of a nearly complete female wasp in ventral view. Body 36.5 mm long, Head 4.5 mm long, 6.0 mm wide; thorax 11.0 mm long, 9.0 mm wide; abdomen 21.0 mm long, 9.5 mm wide; ovipositor 19.0 mm long; hindwing 20.0 mm long; forewing 28.0 mm long, 8.0 mm wide.

The specimen is dorsoventrally embedded, its head is almost completely preserved, the gena has no or almost no pits in its central area. The rest of the body shows no distinct details, except for the ovipositor which is quite prominent. The semicircular rami valvularum at the base of the ovipositor are preserved, but its tip is broken, and no details are observable. The wings lie beside the body, the venation similar to those of the three specimens already attributed to Urocerus ligniticus ( Piton, 1940) , as described and figured in Nel (1988), with the wing membrane apically undulated.

Discussion. As discussed by Nel (1988) and Fidalgo & Smith (1987), the preserved character combination of the fore wing venation allows no differentiation from Urocerus , crossvein 2r-m is present, veins Rs and M meet at the same point; crossvein 2m-cu meets M apical to where crossvein 2r-m meets M; basal stub of Cu1 absent; basal stub of 3A absent. Additionally, this fossil has one of the autapomorphies of Urocerus given in Schiff et al. (2012), i.e. a gena without or almost without pits in its central area. Thus the new fossil specimen supports the attribution of U. ligniticus to the genus Urocerus . All the specimens of Urocerus ligniticus have the same shape of the basal part of Rs, curved and nearly perpendicular to the radial stem and aligned with the basal part of M. Modern Urocerus spp. have the same vein more reclined.

Figures

FIGURE 4. Urocerus ligniticus, new additional specimen, MNHN coll. no. JMP-Menat- 801, photograph of whole fossil. Scale bar represents 5 mm.

FIGURE 5. Urocerus ligniticus, new additional specimen, MNHN coll. no. JMP-Menat- 801, detail showing fore wing venation, drawing. Labelling of longitudinal veins in capital letters, cross-veins in small letters. Scale bar represents 5 mm.