Proironia gibbera, Grimaldi, 2018

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

Proironia gibbera , new species

Figures 13 , 41

DIAGNOSIS: Differs from the other species of the genus, also in Burmese amber, by the following: Head broader, concavity of occiput not nearly as deep; pedicel lobe long, more fingerlike, extended>0.5× the length of basal flagellomere (vs. less than this, lobe more triangular); notopleural, postalar setae shorter; thorax deeper, scutum more dome shaped (vs. slightly flattened on top); pro- and mesocoxae not setose (vs. with dense, fine setae); mesofemur with longitudinal groove, nearly length of femur (vs. without); wing with costal edge convex (vs. flat), apical fork of Sc-R 1 larger; apex of wing broadly rounded (vs. acute); fork of M 1 -M 2 with very short stem; crossvein dm-cu oblique to M 2 and CuA 1 (vs. perpendicular).

DESCRIPTION: Head: Rather broad, depth/ width 0.66. Occiput near posterior margin of eyes rimmed with row of stiff, whitish setae. Eyes : Bare, fully separated in female by distance slightly greater than outside width of lateral ocelli; no differentiation of facets. Frons: Dark brown, largely bare, with a few fine, scattered, minute setulae; lateral margins parallel, modest emarginations around bases of antennae; median furrow present, faint; no ocellar, postocellar or frontal setae present. Face below antennae relatively short ; oral cavity exposed anteriorly; clypeus broad but narrow; oral margin rimmed by protruding membrane. Vibrissa absent. Antenna : Bases very close, oval ; scape very small, conical; pedicel with fingerlike lobe inserted into lateral and mesal surfaces of basal flagellomere; basal flagellomere subcircular, laterally flattened; arista terminal, with 1 or 2 small basal articles (not clearly observed); arista bare. Mouthparts: Compact, not protruding beyond level of basal flagellomeres. Palp small, globular, light in color ; labellum small, laterally flattened, extended slightly beyond level of palps. Thorax: Very deep, depth ca. 1.1× the length ; scutum arched, almost hemispherical in profile. Scutum with scattered, very fine, decumbent setulae (barely visible); one pair of dorsocentral setae, short, stout, very close to anterior margin of scutellum; scutellum with 4 pairs of short, stout setae; 4 notopleural setae, located just above pleural cleft and anterior to transverse suture; 2 postalar setae; prescutellum well developed, lenticular. Wing: Relatively broad, width/length 0.51, apex broadly rounded, anterior (costal) edge convex (not flat); membrane entirely glassy, no microtrichia (even near wing margin). Vein C ends at apex of R 4 +5. Sc long, fused to R 1 for 0.62× its length, both veins free at base and apex. R 2 +3 and R 4 +5 long, nearly parallel ; crossvein br-m very short; cell d long and narrow (L/ W 5.55), apex acute (crossvein dm-cu oblique). M 1 and M 2 joined at base by very short stem connecting to cell d; cell cup narrow, apex acute. A 1, A 2, anal lobe and alula not entirely visible.

Legs: Slender. All coxae with a few, fine, light setae; femora without macrosetae. Protibia with thick, short, preapical seta on mesal surface, ca. 10 short transverse, ctenidial-like rows of fine setae, apical row long and comblike; tarsomeres 1–4 with short ctenidial combs. Mesofemur with narrow but well-defined longitudinal groove on ventral surface (nearly length of femur), to which tibia must fit against. Mesotibia with minute, spurlike lobe on ventral surface, spurlike ventroapical sea; tarsomeres 1–4 with short rows transverse ctenidia. Metatarsus same as mesotarsus. Pretarsus with claws well developed, pulvilli slightly shorter than claws; empodium setiform.

Abdomen: Relatively short, tapered apicad; with fine, short, scattered setulae on tergites and sternites, no macrosetae. Eight tergites and 7 sternites visible, well developed, narrow pleural membrane exposed. Dorsal margin of tergite 7 very short, hidden beneath posterior margin of tergite 6. Cercus 1-segmented. Female Terminalia: Largely retracted, not visible.

SPECIMENS EXAMINED: Holotype, female, AMNH Bu-SE07, in Burmese amber. In excellent condition.

ETYMOLOGY: From Latin gibber (L., “hunched”).

Figures

FIG. 13. Proironia gibbera, n. gen., n. sp. (Ironomyiidae), holotype female in Burmese amber, AMNH Bu-SE7. A–C. Habitus, in ventral (A), right lateral (B), and left lateral (C) views. D, E. Head, in frontal and ventral views, respectively. F. Wing. G. Terminalia, left lateral view.

FIG. 41. Proironia gibbera, n. gen., n. sp. (Ironomyiidae), holotype female in Burmese amber, AMNH Bu-SE7. A. Frontal view of head. B. Left lateral view of thorax. C. Abdominal apex. D. Proleg: femur and tibia, lateral view.