Chasmatonotoides longiantennata, Published, 2007

Published, First, 2007, Chironomid midges from early Eocene amber of France (Diptera: Chironomidae), Zootaxa 1404, pp. 1-66 : 33-35

Chasmatonotoides longiantennata n. sp.

( Figs. 30, 31)

Etymology: This species is named for the long antenna of this taxon.

Diagnosis: Distinctly smaller than C. deharvengi n. sp., 2 prealers instead of 1.

Description: Head 0.28 mm long, deformed; ocelli absent; antenna 0.48 mm long, much longer than head, distinctly hairy, with 13 flagellomeres covered with long setae (shortest 0.03 mm long, longest 0.24 mm long), pedicel broad and short, rounded, 13 th flagellomere 0.23 mm long, with apical nipple but without subapical setae; eye bare, with dorsomedial extension; mouthparts lacking functional mandibles; 5 palpomeres with setae; frontal and outer setae absent, 2 postoculars and 1 inner vertical setae. Thorax 0.4 mm long, 0.22 mm wide, 0.4 mm high; postnotum bare, with longitudinal median groove; surface of scutellum with 4 long setae visible in 1 row; scutal tubercle absent; acrostichals not visible, probably absent, dorsocentrals uniserial; scutum FIGURE 31. Chasmatonotoides longiantennata n. sp., holotype PA 1413, drawing of male genitalia (scale bar = 0.1 mm).

with median longitudinal groove; 2 prealar setae, 1 supraalar setae; epimeron II and preepisternum bare. Wing macropterous, 0.88 mm long, 0.24 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 weakly sclerotized, not divided into R 2 and R 3; only M 1+2 and M 3+4 present; cross­vein MCu absent; squama bare. Halter 0.12 mm long. Fore femur 0.32 mm long, tibia 0.46 mm long, tarsus 0.56 mm long; mid femur 0.34 mm long, tibia 0.4 mm long, tarsus 0.32 mm long; hind femur 0.32 mm long, tibia 0.42 mm long, tarsus 0.46 mm long; 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; pulvilli present. Abdomen 0.82 mm long; gonostylus 0.04 mm long, 0.01 mm wide, simple, elongate, without subapical megasetae, seemingly bare; gonocoxite 0.08 mm long, 0.01 mm wide, with long setae on outer surface; inferior volsella subtriangular with setae apically; superior volsella well developed, narrow and elongate, without setae; anal point narrow and elongate, 0.06 mm long, 0.05 mm wide at base, with few long setae at base.

Discussion: Placement of these fossils in Orthocladiinae is supported by the characters stated above. According to the key to the Holarctic orthocladiine genera of Cranston et al. (1989), Chasmatonotoides n. gen. would fall near the recent genus Chasmatonotus . But Chasmatonotus differs from Chasmatonotoides by the following characters: male antenna short, plume reduced, with only five flagellomeres in Chasmatonotus , unlike 13 distinctly hairy flagellomeres in Chasmatonotoides ; eye without dorsomedial extension; preepisternals present; anal lobe strongly obtuse; squama without setae (but sometimes up to 5 setae present); pseudospurs present on tarsomeres 1 and 2 of mid and hind legs; and anal point prominent, short and with short fine setae. All these characters are absent or different in Chasmatonotoides . Parachasmatonotus differs from Chasmatonotoides in the following characters: 11 flagellomeres; eye without dorsomedial extension and 10 prealar setae (unlike two prealar setae). The presence of setae on the squama and the wing membrane and the bifurcate gonostylus in Pseudochasmatonotus exclude affinities with Chasmatonotoides . For these reasons we establish a new genus.

Material: Holotype PA 1413 (male), paratype PA 318 (3/3) (male).