Chaetocladius petruleviciusi, Published, 2007

Published, First, 2007, Chironomid midges from early Eocene amber of France (Diptera: Chironomidae), Zootaxa 1404, pp. 1-66 : 27-29

Chaetocladius petruleviciusi n. sp.

( Figs. 23, 24)

Etymology: This species is named for our friend and colleague Dr. Julian Petrulevicius ( Argentina).

Diagnosis: Eye apparently bare (if pubescent, not visible under high magnification); subapical setae on last male flagellomere; wing membrane bare, but with coarse punctation; scutum without median longitudinal groove; epimeron II and posterior mesanepisternum II bare; lateral spines of spurs of mid and hind tibiae diverging from shaft of spur (main diagnostic character); gonostylus single, without lobes, and not triangular in shape.

Description: Head deformed; ocelli absent; antenna 0.60 mm long, much longer than head, distinctly hairy, with 13 flagellomeres covered with long setae (shortest 0.06 mm long, longest 0.3 mm long), subapical setae, pedicel broad and short, rounded, 13 th flagellomere 0.29 mm long; eye apparently bare, may be pubescent but not visible, with small dorsomedial extension, with 3 rows of ommatidia at minimum width; mouthparts lacking functional mandibles; 5 palpomeres with setae; postocular and frontal setae not visible, may be absent, 6 inner and outer vertical setae. Thorax 0.61 mm long, 0.57 mm high; postnotum bare, with visible longitudinal median groove; surface of scutellum with few long setae; scutal tubercle absent; acrostichals not visible, probably absent, dorsocentrals uniserial; scutum without median longitudinal groove; 2 prealar setae, no supraalar setae visible, may be absent; epimeron II, posterior mesanepisternum II, and dorsal antepronotum bare. Wing macropterous, 1.19 mm long, 0.26 mm wide, hyaline, membrane bare, but with coarse punctation; 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; only M 1+2 and FIGURE 24. Chaetocladius petruleviciusi n. sp., holotype PA 15016, drawing of male genitalia; a, dorsal view; b, ventral view (scale bar = 0.2 mm).

M 3+4 present; cross­vein MCu absent. Halter 0.15 mm long. Fore femur 0.37 mm long, tibia 0.51 mm long, tarsus 0.50 mm long; mid femur 0.39 mm long, tibia 0.42 mm long, tarsus 0.40 mm long; hind femur 0.40 mm long, tibia 0.46 mm long, tarsus 0.61 mm long; ta4 of all legs cylindrical, not cordiform; fore tibia with 1 long spur, mid and hind tibiae with 2 long spurs with lateral spines diverging from shaft of spur; ta1 and ta2 of mid and hind tibiae with 2 strong spurs, claw on all legs simple; pulvilli absent. Abdomen 1.05 mm long; gonostylus single, narrow and elongate, 0.05 mm long, 0.009 mm wide, hinged to gonocoxite and folded inward, with apical megasetae; gonocoxite 0.2 mm long, 0.04 mm wide, with long setae apically and on outer surface; anal point present, but small and reduced.

Discussion: This Orthocladiinae can be attributed to the genus Chaetocladius on the basis of the following characters and the key of Cranston et al. (1989): macropterous; wing without thick clavus; scutum without median longitudinal groove; eye apparently bare (if pubescent, not visible under high magnification); wing membrane bare; epimeron II and posterior mesanepisternum II bare; and lateral spines of spurs of mid and hind tibiae diverging from shaft of spur (main diagnostic character). This last character separates Chaetocladius from the other Orthocladiinae , except Tokunagaia Saether, 1973 , and some Eukiefferiella Thienemann, 1926 . The main differences between Chaetocladius and these two genera are the presence of a subapical seta on the last male flagellomere and the wing membrane with coarse (instead of fine) punctation ( Halvorsen & Saether 1987, Cranston et al. 1989). Both these characters are present in C. petruleviciusi n. sp. The gonostylus is single, without several lobes, and not triangular in shape, which suggests affinities with the subgenus Chaetocladius and the ‘ piger, vitellinus & acuticornus groups’. It is not possible to compare this fossil with all recent species of this genus.

Evenhuis (1994) listed no fossil Chaetocladius . Seredszus (2003) described (but did not name) a Chaetocladius from Baltic amber. It differs from C. petruleviciusi n. sp. in its very large and long anal point.

Material: Holotype PA 15016, (male).