Orthocladiinae, Edwards, 1929

Published, First, 2007, Chironomid midges from early Eocene amber of France (Diptera: Chironomidae), Zootaxa 1404, pp. 1-66: 42

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Orthocladiinae   genus and species D

Description: Head 0.38 mm long, deformed; ocelli absent; antenna 0.75 mm long, much longer than head, distinctly hairy, covered with long setae (shortest 0.01 mm long, longest 0.4 mm long), pedicel broad and short, rounded, terminal flagellomere long, without subapical setae; eye bare, dorsomedial extension not visible; mouthparts lacking functional mandibles; 5 palpomeres with setae; postocular, frontal, inner and outer vertical setae not visible. Thorax 0.64 mm long, 0.48 mm high; postnotum bare; scutellum not visible; scutal tubercle not visible; acrostichals and dorsocentrals not visible; scutum without median longitudinal groove; no prealar or supraalar setae; epimeron II and preepisternum bare. Wing macropterous, 1.58 mm long, 0.36 mm wide, hyaline, membrane bare; anal vein An 2 absent; radius with 3 branches R 1, R 2+3 and R 4+5, R 2+3 not divided into R 2 and R 3; costa not extended beyond R; only M 1+2 and M 3+4 present; cross­vein MCu absent; anal lobe not developed; squama bare. Halter 0.24 mm long. Fore femur 0.48 mm long, tibia 0.6 mm long, tarsus 1.02 mm long; mid femur 0.48 mm long, tibia 0.44 mm long, tarsus 0.62 mm long; hind femur 0.5 mm long, tibia 0.54 mm long, tarsus 0.8 mm long; tarsomere ta4 of all legs cylindrical, not cordiform; fore tibia with 1 long spur, mid and hind tibiae with 2 long spurs, hind tibial comb well developed. Abdomen 1.46 mm long, 0.16 mm wide; gonostylus simple, broad and short, 0.04 mm long and 0.03 mm wide, with strong apical megasetae, hinged to gonocoxite and folded inward; gonocoxite 0.1 mm long, 0.03 mm wide, with long setae apically and on outer surface; anal point narrow and short, 0.03 mm long, 0.04 mm wide at base, with few short setae on base; inferior volsella simple and elongate, without setae.


Discussion: In the key to Holarctic orthocladiine genera of Cranston et al. (1989), this Orthocladiinae   falls in couplet 91 because of the following characters: wing well developed; without thick clavus; scutum without median longitudinal groove; eye bare; wing without setae; epimeron II and preepisternum bare; no lateral spines on spurs of mid and hind legs; anal point without strong lamellate seta laterally and apicodorsally; squama bare; male antenna without strong straight subapical seta; gonostylus simple; and tarsomere 4 cylindrical, not cordiform. It is not possible to determine if the pars ventralis is present between the gonocoxite bases. Thus, we cannot determine the exact affinities of this fossil species, although it is different from those already described from the Oise amber.

Material: Specimen PA 11432 (male).