Pseudoxyelocerus bascharagensis, Nel & Petrulevicius & Henrotay, 2004

Nel, André, Petrulevicius, Julián F. & Henrotay, Michel, 2004, New Early Jurassic sawflies from Luxembourg: the oldest record of Tenthredinoidea (Hymenoptera: “ Symphyta ”), Acta Palaeontologica Polonica 49 (2), pp. 283-288 : 287

Pseudoxyelocerus bascharagensis sp. nov.

Figs. 3 , 4 .

Holotype and only known specimen: MNHN−LP−R.11198 (IB00976a−b), Part and counterpart of a well−preserved forewing.

Type locality: Bascharage, Grand−Duché−du−Luxembourg ( Henrotay et al. 1998).

Type horizon: Early Toarcian.

Etymology: After the outcrop Bascharage.

Diagnosis.—Same as for the genus.

Description.—Forewing hyaline, 7.8 mm long, 3.1 mm wide; vein Sc long parallel, strongly approximate to but distinctly separated of R; Sc2 very short, 0.05 mm long, Sc1 oblique, 0.1 mm long, ending on C 0.4 mm basal of Rs; Rs very short but distinct, 0.2 mm long, not aligned with M; M + Cu basally curved but not angled; base of M 2.4 mm from wing base; M strongly curved, 1.1 mm long; Rs + M 0.6 mm long; pterostigma 1.4 mm long, 0.5 mm wide; cross−vein 2r−rs 0.6 mm long, from a position near apex of pterostigma to a position distinctly distal to 2r−m; no supplementary cross−vein in cell [3R1]; Rs not distally forked; vein “a” oblique, 1.0 mm basal of 1cu−a; cell [1M] very large, 2.0 mm long, 0.8 mm wide; cell [1R1] small, 0.7 mm long, 0.6 mm wide; cell [2Cu] small, 0.9 mm long, 0.4 mm wide; cell [Rs] elongate, close distally, 1.4 mm long, 0.5 mm wide; cell [2A] triangular, 1.3 mm long; vein 2A + 3A with a strong basal double curve; veins M and Cu shortly but distinctly extended distal of the levels of 3r−m and 2m−cu respectively.

Discussion.—After the phylogeny of the Hymenoptera of Rasnitsyn (2001), mainly inspired from Ronquist et al. (1999), and globally congruent with the analysis of Schulmeister et al. (2002), Pseudoxyelocerus bascharagensis gen. et sp. nov. has three of the main forewing synapomorphies of the clade Tenthredinoidea sensu Rasnitsyn (2001: fig. 331), i.e., cell [1M] (= cell 1mcu sensu Rasnitsyn 2001) large (character 91, state 1 of Ronquist et al. 1999); cross−vein 2r−rs (= 2r sensu Ronquist et al. 1999) from a position near apex of pterostigma to a position distinctly distal to 2r−m (character 84, state 1 of Ronquist et al. 1999) (character unknown in Argidae and Pterygophoridae because 2r−rs is absent in these groups); vein Rs (= first abscissa of Rs sensu Ronquist et al. 1999; = RS sensu Rasnitsyn 2001) short before its fusion with vein M (character 77, state 1 of Ronquist et al. 1999) (but character convergently present in Pamphiliidae , also Schulmeister (2003) noted that some variation can affect this structure within a genus or even within a species). Pseudoxyelocerus bascharagensis gen. et sp. nov. can be included in the Tenthredinoidea . This taxon has not the character state “Sc appressed to or fused with R” (character 74, state 1 of Ronquist et al. 1999; see also Schulmeister, 2003: 214), which is an apomorphy of the Tenthredinoidea minus Xyelotomidae . This plesiomorphic state of character is not sufficient alone to include Pseudoxyelocerus bascharagensis gen. et sp. nov. in the fossil family Xyelotomidae , most basal lineage of this superfamily. Nevertheless, we provisionally attribute it to this family because of its great similarities with Xyelocerus admirandus .

Figures

Fig. 3. Photograph of Pseudoxyelocerus bascharagensis gen. et sp. nov., holotype MNHN−LP−R. 11198. A. Part. B. Counterpart. Scale bars 1 mm.

Fig. 4. Composite reconstruction of Pseudoxyelocerus bascharagensis gen. et sp. nov., holotype MNHN−LP−R. 11198; scale bar 2 mm.