Palaeopetia Zhang, 1987

Grimaldi, David A., 2018, Basal Cyclorrhapha In Amber From The Cretaceous And Tertiary (Insecta: Diptera), And Their Relationships: Brachycera In Cretaceous Amber Part Ix David A. Grimaldi, Bulletin of the American Museum of Natural History 2018 (423), pp. 1-97 : 1-97

Palaeopetia Zhang

Palaeopetia Zhang, 1987: 595 .

Sinolesta Hong and Wang, 1988 (synonymy by Mostovski, 1995). Type species S. lata (Hong and Wang) .

DIAGNOSIS: Vein Sc fused to R 1 for most of their lengths; pterostigma (between apices of Sc and R 1) well sclerotized; M 1 -M 2 forked, with short stem connected to apex of cell d; crossvein dm-cu perpendicular to longitudinal veins (not oblique). As seen in at least the two species in Burmese amber: pedicel without fingerlike lobe; flagellomere 1 with distinctive seam on lateral and mesal surfaces; wing membrane largely glassy, with microtrichia only at trailing margin of wing; acrostichals numerous, scattered, as in Cretonomyia (not in 2 rows as in Ironomyia ); scutellar setae larger than in Ironomyia ; thorax with 4 notopleural, 1 large pair dorsocentral, 1–2 large postalar setae; midleg with large stiff setae, 1 on femur, 3–5 on tibia.

TYPE SPECIES: P. laiyangensis Zhang, 1987 . Early Cretaceous, China (compression).

COMMENTS: There are nine species of Palaeopetia described thus far, all of them compressions from the Cretaceous. Besides the type species the others are the following: P.lata (Hong and Wang) (Early Cretaceous, China); P. tertia Mostovski , P. volacris Most. , P. longisaetigera Most. , P.mina Most. , P. commemorabilis Most. , P. armata Most. , P. bellula Most. , P. asaetigera Most. (Cretaceous of Eurasia and Siberia). These species were diagnosed largely on the basis of subtle differences in wing vein proportions ( Mostovski, 1995b), nonetheless suggestive of significant past diversity of ironomyiids. I have examined some of the specimens described by Mostovski (1995b), including all of the types.

The amber species reveal the plesiomorphic nature of the genus, which appears to be a sister group to all other fossil and living ironomyiids based on the antennal structure and retention of some microtrichia on the wing membrane (fig. 37). Even though Palaeopetia dorsalis , n. sp., and P. terminus , n. sp., are known only from opposite sexes, it is very doubtful that the species differences are sexually dimorphic, given especially the positions of the arista, setation of the thorax, and microtrichial patterns on the wing.