Tenthredinoidea Latreille, 1802

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 : 284-286

Superfamily Tenthredinoidea Latreille, 1802 Family Xyelotomidae Rasnitsyn, 1968

Type genus: Xyelotoma Rasnitsyn, 1968 (type species X. nigricornis Rasnitsyn, 1968 , Upper Jurassic, Callovian–Kimmeridgian or Oxfordian–Kimmeridgian ( Zherikhin and Gratshev 1993; Mostovski and Martínez−Delclòs 2000), Karatau, Chimkent region, Southern Kazakhstan).

Included genera.— Xyelocerus Rasnitsyn, 1968 (type species Xyelocerus admirandus Rasnitsyn, 1968 , Upper Jurassic, Callovian–Kimmeridgian or Oxfordian–Kimmeridgian, Karatau, Chimkent region, Southern Kazakhstan).

Pseudoxyela Rasnitsyn, 1968 (type species P. heteroclita Rasnitsyn, 1968 , Upper Jurassic, Callovian–Kimmeridgian or Oxfordian–Kimmeridgian, Karatau, Chimkent region, Southern Kazakhstan).

Undatoma Rasnitsyn, 1977 (type species U. dahurica Rasnitsyn, 1977 , Upper Jurassic/Lower Cretaceous, Unda river, Chita Province, Transbaikalia (Far Eastern Russia); other species:? U. undurgensis Rasnitsyn, 1990 ,? U. taksha Rasnitsyn, 1990 , both from the Lower Cretaceous of Transbaikalia, U. rudwickensis Rasnitsyn and Jarzembowski, 1998 , Lower Cretaceous, Lower Barremian, West Sussex, England, U. stigmatica Rasnitsyn and Jarzembowski, 1998 , Lower Cretaceous, Upper Berriasian, Dorset, England, U. bicolor Rasnitsyn and Jarzembowski, 1998 , Lower Cretaceous, Upper Hauterivian, Surrey, England).

Liaotoma Ren et al., 1995 (type species L. linearis Ren et al., 1995 , Late Jurassic or Lower Cretaceous?, Liaoning Province, China). Ren et al. (1995: 194, text−fig. 3−69) only compared this taxon with Dahurotoma Rasnitsyn, 1990 and “ Protenthredo ” Hong, 1982. In fact, L. linearis shows no significant difference with U. rudgwickensis , except, maybe, in the shape of the pterostigma, which is apparently narrower in L. linearis than in Undatoma . A revision of the type specimen of L. linearis is necessary in order to determine whether Liadotoma is a junior synonym of Undatoma .

Dahurotoma Rasnitsyn, 1990 (type species D. robusta Rasnitsyn, 1990 , Lower Cretaceous, Transbaikalia).

Leridatoma Rasnitsyn and Ansorge, 2000 (type species L. pulcherrima Rasnitsyn and Ansorge, 2000 , Lower Cretaceous, Spain).

Davidsmithia Pagliano and Scaramozzino, 1990 , one species D. suni ( Hong, 1982) , Upper Jurassic/Lower Cretaceous, Guyong Basin, Neimenggol Region, China. D. suni was originally described in the genus Protenthredo Hong, 1982 , as the type genus of the fossil family Protenthredinidae Hong, 1982 . As the generic name Protenthredo was preoccupied by Protenthredo Pongracz, 1928 (in Tenthredinidae ), Pagliano and Scaramozzino (1990: 5, line 10) proposed a generic name Davidsmithia for this taxon, but the same authors proposed the genus name Thomasia in the same page, line 45. Abe and Smith (1991) noted the problem but did not solve it. We propose as the valid name the first one: Davidsmithia . Rasnitsyn and Ansorge (2000: 59) erroneously indicated that Pagliano and Scaramozzino proposed the new name Xaxexis to replace Protenthredo Hong, 1982 , but in fact these last authors (1990: 6) proposed Xaxexis to replace Euryxyela Hong, 1984 . Abe and Smith (1991) put Protenthredo Hong, 1982 in Xyelotomidae , without further explanation, and did not synonymize the Protenthredinidae with the Xyelotomidae . A revision of the type specimen is necessary before any definite conclusion about the position of this enigmatic genus.

Vitimilarva Rasnitsyn, 1969 (type species V. paradoxa Rasnitsyn, 1969 , Early Cretaceous, Baissa, Vitim river, Transbaikalia). This species is based on a larva that Rasnitsyn (1969) put in “Tenthredinidea incertae sedis ” but that was transferred latter in to the Xyelotomidae ( Rasnitsyn 1990; Abe and Smith 1991).

Kuengilarva Rasnitsyn, 1990 (type species K. inexpectata Rasnitsyn, 1990 , Lower Cretaceous, Transbaikalia). This taxon is also based on a larva that Rasnitsyn (1990) attributed to the Xyelidae or Xyelotomidae .

Remarks on the family composition.— Rasnitsyn (1988: 120, fig. 1; 1996: 14; 2002: fig. 331) clearly considered the Xyelotomidae as a paraphyletic, “ancestral” group of the other Tenthredinoidea , with no recorded autapomorphies. At least, the three genera Undatoma , Liaotoma , Leridatoma , and Davidsmithia have their forewing vein Sc “not developed, at least not as a longitudinal trunk” ( Rasnitsyn 1977 —English translation in 1978, 1990; Hong 1982: 93, fig. 19; Ren et al. 1995: 194, text−fig. 3−69; Rasnitsyn et al. 1998). This character state is currently supposed to be the unique apomorphy in the wing venation of the Tenthredinoidea minus Xyelotomidae ( Rasnitsyn 1988, 2001; Ronquist et al. 1999; Schulmeister, 2003). Thus, it would support the possible exclusions of Undatoma , Liaotoma , Leridatoma , and Davidsmithia from the Xyelotomidae . The longitudinal part of Sc is absent or very weak and Sc1 and Sc2 are absent in Xyelocerus admirandus (after Rasnitsyn 1968: 226, text−fig. 35, 1996: fig. 5). On the contrary, the genus Pseudoxyela has “retained” Sc and R separated and parallel, and the forewing Sc is basally free and distally fused with R in Dahurotoma and probably Xyelotoma .

The structure of the prosternum (character 34, state 1 of Ronquist et al. 1999) is a potential apomorphy of the Xyelotomidae but it is present in several other hymenopteran groups (e.g., Megalyridae and Stephanidae ). Furthermore, it is unknown in several species currently attributed to the Xyelotomidae . At least in Undatoma and Thomasia , the body characters are too badly known and cannot be used in a phylogenetic analysis. Ren et al. (1995) did not describe the body structures of Liaotoma . This suggests that the Xyelotomidae could be an artificial group of taxa with no direct common ancestor.

Only a detailed phylogenetic revision of the Xyelotomidae and the Tenthredinoidea will help to solve the problems in the definition of the Xyelotomidae and the positions of the genera Undatoma , Liaotoma , Leridatoma , and Davidsmithia .

Lastly, it is not possible to have a correct proof of the attribution of Vitimilarva and Kuengilarva to the strictly fossil family Xyelotomidae , because the hymenopteran larvae are very different from the adults.