Culicomorpha, Hennig, 1948

BLAGODEROV, VLADIMIR, GRIMALDI, DAVID A. & FRASER, NICHOLAS C., 2007, How Time Flies for Flies: Diverse Diptera from the Triassic of Virginia and Early Radiation of the Order, American Museum Novitates 3572, pp. 1-40 : 12

Culicomorpha indet.

figures 4c–f, 5a, b, 9b, c

Several specimens from the Solite quarries have their venation obscured, so they can not be described and named formally. Some of these specimens, however, are otherwise exquisitely preserved, retaining some distinctive features that allow placing them within the infraorder Culicomorpha . Despite differences in sizes and leg lengths, specimens VMNH 808, 873, 932, 951, 2956, and 3056 possess: (1) slender moniliform antennae with long setae on each flagellomere; (2) a round antennal pedicel that is larger than the scape; (3) round (vs. reniform or emarginate) eyes with large facets; (4) a broad katepisternum that is rounded ventrally; (5) a short, arched mesonotum that nearly overhangs the pronotum; (6) small, unprotruding scutellum; (7) wide insertion of the abdomen; and (8) male genitalia curved dorsally. Features 2, 5, and 8 are particularly distinctive to Culicomorpha , but venation is needed to confirm this. Most significantly, VMNH 951 bears a long, slender proboscis that is nearly twice as long as the head height (figs. 4d, e; 9b, c).

Body and leg proportions of VMNH 951 are very similar to that of other culicomorphans (VMNH 808, 873, 932, 2956, 3056), but it is doubtful that the specimens are conspecific, since there are no known instances in any living species of Diptera where a proboscis is so dramatically dimorphic. In various Recent species of biting midges the styletlike mandibles of females are well developed and used to puncture the skin of their host in order to feed on blood; males feed on nectar and have vestigial mandibles, but the proboscis size barely differs with that of females. Since angiosperms did not appear until nearly 100 Ma later, it is possible that the proboscis was used to probe Bennettitalean or Gnetalean reproductive structures, and bennettitaleans occurred in the Triassic of Virginia. Recent Gnetales produce pollination droplets, on which insects feed, but these are external, making a long proboscis unnecessary. VMNH 951 is the earliest fossil evidence of a structure in Diptera specialized for blood feeding, in a group in which the ground-plan adult diet is hematophagy ( Grimaldi and Engel, 2005; Lukashevich and Mostovski, 2003). If this is the case, VMNH 951 is the earliest known blood-feeding insect. It is not until the Jurassic that definitive insect ectoparasites appeared, and not until the Cretaceous that definitive hematophagous insect groups appeared ( Grimaldi and Engel, 2005).

INFRAORDER BIBIONOMORPHA

The composition of the infraorder is in flux, partly because it is paraphyletic with respect to the higher flies, the Brachycera . It includes diverse Mesozoic taxa, such as Eliidae and various families of sciaroids, in addition to the families discussed below. The infraorder also includes very diverse Recent families, such as Mycetophilidae and Cecidomyiidae , totaling 8,000 species in some 25 families. In contrast to the other major infraorders of nematocerous flies, larvae of Bibionomorpha and those of their stem group (the Brachycera ) are almost exclusively terrestrial, being saprophagous, fungivorous, phytophagous, and sometimes predatory.

FAMILY PROCRAMPTONOMYIIDAE KOVALEV, 1985

A small family of basal bibionomorphs known from Late Triassic to Early Cretaceous of North America, Australia, Asia, and Europe. Kovalev (in Kalugina and Kovalev, 1995) referred the family to Anisopodoidea based on the presence of a discal cell. However, a more accurate placement would be at the base of all Bibionomorpha s.l. ( Shcherbakov et al., 1995).