Psectrosciara fossilis, Nel, André & Coty, David, 2016

Nel, André & Coty, David, 2016, A fossil dung midge in Mexican amber (Diptera: Scatopsidae), Palaeontologia Electronica 51 (9), pp. 1-6 : 2-5

Psectrosciara fossilis sp. nov.

( Figures 1-3 )

zoobank.org/ EB43CB40-EE54-4AB4-8FCE-C7AB481FA1FA

Etymology. Named after the fact that it is the first fossil record of the genus.

Holotype. MNHN.F.A57265 stored at the MNHN, Paris.

Type horizon. Late Oligocene–Middle Miocene, Type locality. Salt River mine, Totolapa, Chiapas, Mexico .

Diagnosis. Male characters only. Presence of two foliaceous lobes at the extremity of the gonostyles; base of M1 clearly visible; 10-segmented antennae.

Description. Body 2.7 mm long; head 0.25 mm long, dark; antennae with 10 segments, the first flagellomere very short, last flagellomere bulletshaped; eyes holoptic, lateral margin oblique. Thorax compressed laterally, brown; mesonotum bare, uniformly light brown; scutellum and metanotum light brown. Wing length 1.44 mm, width 0.61 mm; C extending 82% of wing length, Sc short; macrotrichia on all veins and on membrane posteriorly to vein R4+5; membrane covered with microtrichia; all veins brownish, posterior ones less so but clearly contrasting with wing membrane; base of vein M1 more diffuse than other veins but still clearly visible; base of M clearly visible; vein CuA1 not reaching wing margin; A1 strongly curved. Halter with knob and stem bare. Legs brown; fore coxa long, almost as long as femur; tibiae and tarsi not armed with stout, short spine-like setae but tibiae with very short ventro-apical spines; fore tibia with distal half distinctly dilated; mid and hind tibiae gradually dilated in all its length; hind 1st tarsomere longer than other tarsomeres.

Abdomen brown, cylindrical, long, distinctly overpassing tip of wings. Tergite 1 short, wider than long; tergite 2 divided in a small anterior sclerite and a larger posterior sclerite; tergites 3-5 rectangular, longer than wide; tergite 5 somewhat wider; tergite 6 quadrate; tergite 7 somewhat wider than long; tergite 8 short, projecting latero-posteriorly, with very long hairs and a pair of dorsolateral spiracles, well distant each other; tergites 1-8 with an anterior slight emargination, sternite 7 entire.

Genitalia. Epandrium bottle-shaped, with a preapical strangulation; gonocoxites well developed, long, with long hairs; gonostyles very long and narrow, with two leaf-like apical expansions, curved upwards and inwards, with long hairs.

Figures

FIGURE 1. Psectrosciara fossilis sp. nov., holotype MNHN.F.A57265. 1, general habitus; 2, wing; 3, hind leg. Scale bars represent 0.5 mm (1), 0.5 mm (2), 0.25 mm (3).

FIGURE 2. Psectrosciara fossilis sp. nov., holotype MNHN.F.A57265. 1, head; 2, dorsal view of thorax. Scale bars represent 0.5 mm (1) and 0.25 mm (2).

FIGURE 3. Psectrosciara fossilis sp. nov., holotype MNHN.F.A57265. 1, lateral view of thorax; 2, fore tarsi; 3, genitalia. Scale bars represent 0.5 mm (1), 0.25 mm (2), 0.01 mm (3).