Cretadiamesa arieli, 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 : 186-188

Cretadiamesa arieli sp. n.

Figs 18–20

Etymology: After Ariel, son of one of the authors (I.V.).

Description: Head 0.2 mm long. Ocelli absent.Antenna 0.6 mm long, 3 times the length of the head, distinctly hairy, with 13 flagellomeres, all covered with long setae (shortest 0.02 mm, longest 0.4 mm). Scape broad and short, rounded; pedicel very short. Eye bare, with a distinct dorso-medial extension. Mouthparts lacking functional mandibles; palps long, with 5 palpomeres bearing numerous setae, all approximately the same length. Two postocular setae; frontal, inner vertical and outer vertical setae not visible, possibly absent.

Thorax 0.5 mm long, 0.36 mm wide, 0.1 mm high. Postnotum and scutellum with few, rather short setae. Scutum with a central group of acrostichals and 2 lines of sparse dorsocentrals.

Wing macropterous, 1.1 mm long, 0.3 mm wide, hyaline, membrane without setae. Costa ending at apex of R 4+5, near wing apex. Radius with only 3 branches R 1, R 2+3, and R 4+5; R 1 rather long, 3 times as long as R 4+5; R 2+3 simple, closely aligned and parallel to R 1 but very weakly indicated; R 1 and R 4+5 strongly approximate. Cross-vein MCu present in a very basal position, approximately midway between base of M and RM. Fork of Cu nearly opposite RM; Cu 1 weakly curved. Anal vein An 2 absent. Halter 0.18 mm long.

Fore femur length 0.42 mm; mid femur 0.4 mm; tibia 0.6 mm; hind femur 0.48 mm; tibia 0.66 mm. One hind tibial spur visible, curved; hind tibial comb present, disposed in one row.

Abdomen 0.94 mm long, 0.2 mm wide (male); 0.8 mm long, 0.25 mm wide (female). Male genitalia: abdomen with numerous uniform setae; gonocoxite short and broad; gonostylus directed upward, curved and short, with an apical megaseta; inferior volsella not visible and thus reduced or absent. Female genitalia: tergite IX undivided; cerci short with small setae; gonocoxites IX not visible.

Holotype: 365, male. LEBANON: Mont Lebanon district [Mouhafazit Jabal Loubnan]: Hammana/Mdeyrij, Caza Baabda; Early Cretaceous (D. Azar coll.).

Allotype: 349, female, same data as holotype.

Discussion: The allocation of the male and female specimens to the same species is based on their similarity in wing venation. Following the key to Holarctic subfamilies of Oliver and Dillon (1989) and to Palaearctic subfamilies in Saether et al. (2000), Cretadiamesa gen. n. falls in the Prodiamesinae because of the following characters: macropterous; MCu present; R 2+3 very weak, but simple; R 1 and R 4+5 strongly approximate; wing membrane without setae; FCu well distad of MCu. Furthermore, Cretadiamesa has bare eyes, unlike in most recent Diamesinae .Among the non-Holarctic subfamilies, affinities with the Aphroteniinae , Usambaromyiinae and Chilenomyiinae are excluded for the same reasons as above.As in Libanodiamesa , Cretadiamesa differs from the recent prodiamesine genera in its much more basal position of MCu, midway between base of M and RM.

Figures

Figs 18–20. Cretadiamesa arieli gen. et sp. n., male, holotype 365: (18) general habitus, scale bar = 0.5 mm; (19) wing, scale bar = 0.3 mm; (20) details of male genitalia, scale bar = 0.1 mm.