Wadelius libanicus, Veltz & Azar & Nel, 2007

Veltz, Isabelle, Azar, Dany & Nel, André, 2007, New chironomid flies in Early Cretaceous Lebanese amber (Diptera: Chironomidae), African Invertebrates 48 (1), pp. 169-191 : 178-179

Wadelius libanicus sp. n. Figs 7, 8 Etymology: After Lebanon.

Description: Head 0.25 mm long, 0.52 high. Ocelli absent. Antenna 0.8 mm long, more than 3 times longer than head, distinctly hairy, with 14 flagellomeres, flagellomeres 1–13 covered with long setae (shortest 0.05 mm long, longest 0.4 mm long), scape broad and short, rounded, pedicel very short, flagellomere 13 long (0.3 mm), flagellomere 14 evenly tapering from base to apical nipple, 0.09 mm long. Eye bare, with apically expanded dorso-medial extension. Clypeus 0.13 mm long, with few dorsal setae. Mouthparts lacking functional mandible; all palpomeres with numerous setae; labium 0.23 mm. Uniserial postocular setae; numerous long frontal setae visible; inner vertical and outer vertical setae not visible.

Thorax 0.93 mm long, 0.92 mm high; antepronotum bare; postnotum bearing long setae and with longitudinal groove; scutal tubercle present; scutellum with broken setae; numerous acrostichals, supraalar and prealar setae; postanepisternal setae present.

Wing macropterous, 1.6 mm long, 0.42 mm wide, hyaline, covered with macrotrichia. Costa ending just beyond insertion of last branch of radius, produced by 0.06 mm, shorter than cross-vein RM. Radius with only 3 branches R 1, R 2+3, and R 4+5; R 2+3 well separated from R 1 and R 4+5, R 2+3 clearly visible at base and apex but evanescent in its main part; R 2 0.02 mm long, ending in R 1, R 3 0.15 mm long, ending in costa. Only M 1+2 and M 3+4 present; cross-vein MCu present. Cubital fork 0.05 mm proximal to crossvein MCu; cross-vein RM 0.02 mm distal of MCu. Anal vein An 2 absent. Halter 0.2 mm long.

Fore femur length 0.7 mm, tibia 0.82 mm, tarsus 1.08 mm; mid femur 0.7 mm, tibia 0.84 mm, tarsus 0.96 mm; hind femur 0.6 mm, tibia 0.86 mm, tarsus 1.22 mm. Tibial spur formula 1–2–2, with no lateral teeth; two robust and curved claw-like spines on tibial end, 0.04 mm long; hind tibial comb disposed in one row. Fourth tarsomeres of all legs cylindrical, not cordiform; claw simple, not pectinate.

Abdomen 1.4 mm long, 0.4 mm wide. Gonostylus 0.15 mm long; gonocoxite 0.22 mm long, 0.15 mm wide at base, with numerous long setae. Anal point very smooth and broad, though small; 0.04 mm wide at base, 0.05 mm high.

Holotype: Specimen 748A, male. LEBANON: Mont Lebanon district [Mouhafazit Jabal Loubnan]: Hammana / Mdeyrij, Caza Baabda; Early Cretaceous (D. Azar coll.).

Paratype: Specimen 259 (male), same data as holotype.

Discussion: This peculiar tanypodine may deserve a separate tribe. However, one of the most distinct and unique synapomorphies within the Tanypodinae is the comb-like formation of the tibial spurs. The only recent tanypodine without such tibial spurs belongs to the tribe Anatopyniini with the single included genus Anatopynia Johannsen, 1905 . Similarities between Wadelius and this tribe also are found in the extensive thoracic chaetotaxy and in the probable absence of an inferior volsella. The wing venation is also similar although the costa is more produced and the cubital fork is more proximal to cross-vein MCu in Anatopynia . In addition, unlike Anatopynia , Wadelius has a scutal tubercle.

The two genera Tanypus Meigen, 1803 and Nilotanypus Kieffer, 1923 have very rudimentary comb-like structures, which are very difficult to see. Wadelius has similar tibial spurs, but it differs from the former genus in the MCu and cubital fork position, and from the latter in the presence of a divided R 2+3. We tentatively attribute Wadelius to the Anatopyniini .

Figures

Figs 7, 8. Wadelius libanicus gen. et sp. n.: (7) wing, holotype 748A, scale bar = 0.5 mm; (8) male genitalia, paratype 259, scale bar = 0.1 mm.