Orthocladiinae, Edwards, 1929

Published, First, 2007, Chironomid midges from early Eocene amber of France (Diptera: Chironomidae), Zootaxa 1404, pp. 1-66 : 41

Orthocladiinae genus and species B

Description: Head 0.16 mm long, deformed; ocelli absent; antenna 0.25 mm long, much longer than head, distinctly hairy, covered with long setae, pedicel broad and short, rounded, terminal flagellomere long, without subapical setae; eye bare, small dorsomedial extension; mouthparts lacking functional mandibles; 5 palpomeres with setae; postocular, frontal, and inner and outer vertical setae seemingly absent. Thorax 0.35 mm long, 0.21 mm wide, 0.36 mm high; postnotum bare; setae on scutellum not visible; no scutal tubercle but tuft of microtrichia; no acrostichals, dorsocentrals uniserial; scutum without median longitudinal groove; 2 prealar and 1 supraalar setae; epimeron II and preepisternum bare. Wing macropterous, 0.55 mm long, 0.2 mm wide, hyaline, membrane bare; anal vein An 2 absent; radius with 2 branches R 1 and R 4+5, R 2+3 seemingly absent; costa strongly extended beyond R, produced by 0.07 mm; only M 1+2 and M 3+4 present; cross­vein MCu absent; anal lobe not developed; squama bare. Halter 0.08 mm long. Fore femur 0.12 mm long, tibia 0.2 mm long, tarsus 0.23 mm long; mid femur 0.14 mm long, tibia 0.16 mm long, tarsus 0.2 mm long; hind femur 0.18 mm long, tibia 0.2 mm long, tarsus 0.25 mm long; ta4 of all legs cylindrical, not cordiform; fore tibia with 1 long spur, mid and hind tibiae with 2 long spurs. Abdomen 0.42 mm long; gonostylus simple, elongate, 0.02 mm long and 0.008 mm wide, without strong apical megasetae, hinged to gonocoxite and folded inward; gonocoxite 0.06 mm long, 0.03 mm wide, with few long setae on outer surface; anal point and inferior volsella not visible.

4+5

Discussion: In the key to the Holarctic orthocladiine genera of Cranston et al. (1989), this Orthocladiinae falls in couplet 91 because of the following characters: wing well developed, with R, M, and Cu veins distinct; without thick clavus; scutum without median longitudinal groove; eye bare; wing membrane bare; epimeron II and preepisternum bare; no lateral spines on spurs of mid and hind tibiae; anal point without strong lamellate setae laterally and apicodorsally; squama bare; male antenna without strong subapical seta; gonostylus simple; and tarsomere 4 cylindrical. Our fossil falls in the group of genera with a median tuft of microtrichia on the scutum, i.e., Acamptocladius Brundin, 1956 , Epoicocladius Zavrel, 1924 , Lappokiefferiella Tuiskunen, 1986 , Lindebergia Tuiskunen, 1984 , and Parakiefferiella Thienemann, 1936 (for the Holarctic genera). It is not possible to see the genitalia clearly and determine if a pars ventralis is present. Thus, we cannot precisely determine affinities, but this fossil is different from all others of the Oise amber.

Material: Specimen PA 709 (male).