Paraxiphydria, J. Gao, Engel, & T. Gao, 2022

Gao, Jia, Engel, Michael S., Grímsson, Friðgeir, Gu, Lei, Ren, Dong & Gao, Tai-Ping, 2022, The first xiphydriid wood wasp in Cretaceous amber (Hymenoptera: Xiphydriidae) and a potential association with Cycadales, Fossil Record 24 (2), pp. 445-453 : 446-447

Paraxiphydria, J. Gao, Engel, & T. Gao , gen. nov.

Diagnosis

The new subfamily can be distinguished most readily from other lineages of Xiphydriidae by the absence of 1r-rs and 2rs-m in the forewing, as well as the exceptionally short 2M in the forewing, which is scarcely present owing to the proximal position of 1m-cu near the origin of 2Rs. In the hind wing, cell r is open, and 3rs-m and 1m-cu are absent. The open hind wing cell r is likely plesiomorphic (symplesiomorphic with Siricoidea and Orussoidea), and the closed cell r is like Xiphydriinae and Derecyrtinae and is a putative synapomorphy uniting these two subfamilies relative to Paraxiphydriinae . In addition, the anterior margin of the pronotal collar is comparatively straight, while in most extant Xiphydriidae this margin exhibits varying degrees of convexity, although a few species are nearly straight (e.g., some Derecyrta Smith ). The tarsi lack pulvilli (= plantulae, although historically referred to as pulvilli in the xiphydriid literature, these are technically plantulae), a feature that differs from most Xiphydriidae except some species of Derecyrta , which have secondarily lost the pulvilli. The maxillary palpus is pentamerous, the likely plesiomorphic condition for the family.

The classification of Benson (1954) is followed and emended here, with Maoxiphinae Maa, Hyperxiphinae Maa and Euxiphydriinae Maa ( Maa, 1949) all being synonyms of Xiphydriinae . The following key aids the recognition of the new subfamily, as well as the remaining subfamilies and tribes.

Key to subfamilies and tribes of Xiphydriidae

1 Forewing with 1r-rs and 2rs-m present; 2M distinct, as long as or longer than 2Rs, rarely slightly shorter than 2Rs; hind wing cell r closed; hind wing 3rs-m and 1m-cu present; anterior margin of pronotal collar concave: 2

– Forewing with 1r-rs and 2rs-m absent; 2M exceptionally short, scarcely present owing to proximal position

J. Gao et al.: The first xiphydriid wood wasp in Cretaceous amber 447

of 1m-cu; hind wing cell r open; hind wing 3rs-m and 1m-cu absent; anterior margin of pronotal collar comparatively straight: Paraxiphydriinae , subfam. n.

2(1) Pronotal collar with mediodorsal length long, more than tegular length, excavation of anterior margin about equal to mediodorsal length; mesoscutellum with dorsal area margined by carina, typically with a prominent tubercle apically; metapretarsal claw of female enlarged, 1.5× or greater than length of mesopretarsal claw; ovipositor sheaths 0.50–0.65× length of basal plate; tarsi with or without pulvilli (subfamily Derecyrtinae Ashmead ): 3

– Pronotal collar with mediodorsal length short, shorter than tegular length, excavation of anterior margin much greater than mediodorsal length; mesoscutellum without dorsal area defined by carina, lacking tubercle apically; metapretarsal claw of female not enlarged, similar to mesopretarsal claw; ovipositor sheaths 0.65–1.0× length of basal plate; tarsi with pulvilli: Xiphydriinae Leach.

3(2) Metatarsomere V of female shorter than metabasitarsus; metafemur crassate, 3–5× longer than broad; forewing 2r-rs absent (rarely present, occurring in Derecyrta beechei Smith ); head glabrous, shiny and impunctate posterior to ocelli; tarsi with or without pulvilli: Derecyrtini Ashmead.

– Metatarsomere V of female distinctly longer than metabasitarsus; metafemur slender, about 7× longer than broad; forewing 2r-rs present (i.e., marginal cell divided); head with long, erect setae, integument roughened and typically dull; tarsi with pulvilli: Brachyxiphini Maa.

Paraxiphydria J. Gao, Engel, & T. Gao , gen. nov. urn:lsid:zoobank.org:act:7463861B-0BE2-4379-88D3-02D1F9E34A6E

Type species