CHIRONOMIDAE (MIDGES)

Grimaldi, David A., Sunderlin, David, Aaroe, Georgene A., Dempsky, Michelle R., Parker, Nancy E., Tillery, George Q., White, Jaclyn G., Barden, Phillip, Nascimbene, Paul C. & Williams, Christopher J., 2018, Biological Inclusions in Amber from the Paleogene Chickaloon Formation of Alaska, American Museum Novitates 2018 (3908), pp. 1-37 : 27

CHIRONOMIDAE (MIDGES)

Figures 7E , 14 A−D

AMNH WH-3: A complete male nonbiting midge ( Chironomidae ) (body length 1.60 mm), preserved adjacent to a small juvenile spider (fig. 7E). Eyes are bare; pedicel large, subspherical; antenna with long plumosity, apparently having 11 flagellar articles, apical article longest; maxillary palp with four palpomeres, lengths 4> 2 = 3> 1 (fig. 14C). Legs: mesotibia having two bladelike apical spurs (one with fine pectination), apical comb of 11−12 thick, sclerotized, slightly clavate setae (fig. 14D); pretarsal claws simple (untoothed), pulvilli either minute or lost. Wings are very faint, obscuring the venation; no macrotrichia occur on the wing membrane. Male genitalia well preserved: tergite 9 (epandrium) large, shieldlike; gonocoxite large; gonostylus articulating with (not fused to) gonocoxite, bare, flattened and hatchetlike, without discernable apical peg/tooth; pair of inner lobes present, bare; anal point absent (fig. 14A, B). Chironomidae have a rich fossil record, partly because the larvae are aquatic and semiaquatic and both adults and larvae are readily fossilized in lacustrine sediments. The oldest Chironomidae are Triassic, and they are frequently among the most abundant and diverse winged insects in many deposits of amber, such as Eocene Baltic amber and Late Cretaceous ambers from western Canada, New Jersey, and Siberia. The fossil record has been reviewed by Evenhuis (1994). Critical study relies on various microscopic features, and most of the described fossils, done decades to a century ago, require re-description based on modern standards. The male genitalia of the Chickaloon fossil appear most similar to those in the large, widespread subfamily Tanypodinae .

Figures

FIG. 7. Various insect inclusions. A. AMNH WH-12, with legs from a roach (Blattodea), and the legs and distal portions of two wings from a caddisfly (Trichoptera). B. AMNH LC-A4, nymph of Heteroptera (Hemiptera). C, D. AMNH LC-B6, nymphal thrips (Thysanoptera), habitus (C) and detail of antennae (D). E. AMNH WH-3, with inclusion of entire male Chironomidae: Tanypodinae, and juvenile spider.

FIG. 14. Details of various holometabolous insect inclusions. A−D, Male midge (Diptera: Chironomidae: Tanypodinae) (AMNH WH-3): A, B. Male terminalia, dorsal (A) and ventral (B) views. C. Maxillary palp. D. Mesotibial apex (mesal surface). E. Isolated antenna of ant (Hymenoptera: Formicidae) (AMNH GC-A4). F. Detail of highly specialized, entangling hastiseta from larval beetle (Dermestidae: Megatominae) (AMNH LC-II-B4).