Monodiamesa guglielmia, Published, 2007

Published, First, 2007, Chironomid midges from early Eocene amber of France (Diptera: Chironomidae), Zootaxa 1404, pp. 1-66: 59-60

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Monodiamesa guglielmia

n. sp.

Monodiamesa guglielmia   n. sp.

( Figs. 58 –60)

Etymology: We name this species in honor of Jocelyne Guglielmi, librarian at the Laboratoire d’Entomologie, MNHN, for her great help.

Diagnosis: MCu present; R 2+3 simple; wing membrane without setae; FCu distal to MCu; median volsella with long, sclerotized spine­like projection; anal point sharp; gonostylus simple.

Description: Head 0.74 mm long; ocelli absent; antenna 1.16 mm long, much longer than head, distinctly hairy, 13 flagellomeres covered with long setae (shortest 0.02 mm long, longest 0.68 mm long), pedicel broad and short; eye bare, with large dorsomedial extension; mouthparts lacking functional mandibles; palps long, with 5 palpomeres with numerous setae; 5 postocular setae; frontal, inner vertical, and outer vertical setae absent. Thorax 1.26 mm long, 0.66 mm wide, 1.02 mm high; postnotum bare, with median groove, scutellum not visible; scutum with median groove, acrostichals absent, dorsocentrals uniserial, 4 prealars present, supraalars not visible. Wing macropterous, 2.35 mm long, 0.55 mm wide, hyaline; membrane without setae; anal vein An 2 absent; radius with only 3 branches R 1, R, and R 4+5; R simple; costa ending just beyond insertion of last branch of radius, produced by 0.03 mm; cross­vein MCu present, in basal position; FCu distal to MCu; Cu 1 weakly curved, squama fringed. Halter 0.3 mm long. Fore femur 0.9 mm long; tibia 1.4 mm long; tarsus 2.6 mm long; mid femur 1.16 mm long; tibia 1.35 mm long; tarsus 1.4 mm long; hind femur 1.13 mm long; tibia 1.39 mm long; tarsus 1.76 mm long; 2 hind tibial spurs visible (0.07 mm long and 0.06 mm long); hind tibial comb present, arranged in 1 row, 2 pseudospurs on tarsomeres 1 and 2 of mid and hind legs. Abdomen 2.73 mm long, 0.47 mm wide; gonocoxite broad, with numerous long setae on outer surface, 0.28 mm long, 0.12 mm wide at base; gonostylus narrow and elongate, covered with short setae, 0.12 mm long, 0.04 mm wide, hinged to gonocoxite and folded inward, with apical megaseta; median volsella with long, sclerotized spine­like projection; inferior volsella narrow and elongate, superior volsella not visible; anal point present, broad and conical, 0.1 mm long.



Discussion: In the key to Holarctic subfamilies of Oliver and Dillon (1989) and to Palaearctic subfamilies in Saether et al. (2000), Monodiamesa guglielmia   n. sp. falls in the Prodiamesinae Saether, 1976   , because of the following characters: macropterous; MCu present; R 2+3 present, simple; wing membrane without setae; and FCu distal to MCu. Furthermore, M. guglielmia   has a normal plume, unlike the recent diamesine genus Boreoheptagyia Brundin, 1966   , that has a rather similar wing venation. Among the non­Holarctic subfamilies, affinities with the Aphroteniinae   are excluded because M. guglielmia   has retained MCu and R 2+3, but it has a narrow space between R 4+5 and the costa. Usambaromyiinae   have no MCu. The Chilenomyiinae   have MCu in the basal position (less so than in M. guglielmia   ), but no R 2+3. Furthermore, their wings are densely hairy all over, unlike in M. guglielmia   . In the key to genera of Saether (1989), M. guglielmia   would fall near the recent genus Monodiamesa Kieffer, 1922   , because of the following characters: wing membrane without setae; median volsella with long, sclerotized spine­like projection; anal point present; gonostylus simple; and eye with large dorsomedial extension. The early Cretaceous genera Libanodiamesa, Veltz, Azar & Nel, 2007   , and Cretadiamesa, Veltz, Azar & Nel, 2007   , differ from M. guglielmia   in having MCu distinctly more basal ( Veltz et al. 2007).

Material: Holotype PA 4273, (male).

FIGURE 59. Monodiamesa guglielmia   n. sp., holotype PA 4273, photograph of male genitalia.

FIGURE 60. Monodiamesa guglielmia   n. sp., holotype PA 4273, drawing of male genitalia (scale bar = 0.2 mm).