Thereotricha sibirica, BLAGODEROV & GRIMALDI, 2004

BLAGODEROV, VLADIMIR & GRIMALDI, DAVID, 2004, Fossil Sciaroidea (Diptera) in Cretaceous Ambers, Exclusive of Cecidomyiidae, Sciaridae, and Keroplatidae, American Museum Novitates 3433 (1), pp. 1-76 : 9-10

Thereotricha sibirica , new species

Figure 4 , Plate 1B

DIAGNOSIS: Wing membrane without macrotrichia, RS base very basal, oblique, ~2Χ the length of r­m; M3 section long; base of M 1 and M 2 fork at level of tip of R 1; veins R 1, R 5, M 1, M 2, and CuA with long setae.

DESCRIPTION: Body length = 1.83 mm (ho­

lotype)/ 1.84 –1.85 mm (paratypes); wing length = 1.46 mm (holotype)/ 1.25 mm (paratype PIN 3130 /185). Head. Three ocelli present, equal in size, distance of lateral ocellus from median ocellus and eye margin 1.5Χ its diameter. Occiput with numerous small setae. Eyes large, bare, forming incomplete dorsal bridge (separated by twice the facet diameter). Scape and pedicel short, rounded. Flagellum 14­segmented, flagellomeres barrellike, width 1.3Χ the length, covered by short trichia. Palpi 4­segmented. Basal segment small, bacilliform, others short, rounded; antepenultimate segment with round sensory pit dorsomedially, slightly longer than others. Thorax. Antepronotum with one strong seta, proepisternum with six. Proepimeron touches episternum at episternal suture. Mesonotum uniformly setose. Midpleural pit present. Katepistrnum large, expanded caudally. Ventral part of mesepimeron not very narrow, parallel­sided. Laterotergites bare, small. Metepisternum setose, with narrow anteriodorsal cleft. Wing membrane without macrotrichia. Costa ends beyond tip of R 5, one­third the distance between tips of R 5 and M 1. Sc very short, ends free just beyond RS base. RS base proximad, oblique, 1.5Χ r­m length. R 1, R 5, M 1, M 2, and CuA with long setae. R 1 about 0.7Χ wing length. RS base oblique. Crossvein r­m fused with tb and mcu in one horizontal vein. M3 section 1.5Χ as long as fork of M 1 and M 2. M 3+4 reduced, seen as a fold at base only. CuA ends before middle of the wing. Legs. Fore coxae with numerous setae on anterior and distal surfaces, mid coxae with distal rows and several setae on apical part, hind coxae with caudodistal row of setae. Fore tibia with anteroapical pit having two combs of setae. Abdomen setose. Eighth segment slightly shorter than preceding ones. Ninth tergite ovoid, with apical comb of short blunt setae. Gonocoxites stout, triangular in lateral view. Gonostyli small, flat, rectangular, with several apical setae .

MATERIAL: Holotype PIN 3130 /183, male; paratypes, PIN 3130 /182, 3130/184, 3130/ 185, males; all specimens in the same piece of amber. Russia: Taimyr Peninsula , Yantandarkh, coll. 1970.

ETYMOLOGY: The species epithet is in reference to Siberia, the region where the original locality is situated.

Figures

Figs. 4–6. Thereotricha, n.gen. 4. Thereotricha sibirica, n.sp., drawing of amber piece with four embedded specimens, including holotype PIN 3130/183. 5.? T. agapa, n.sp., holotype PIN 3426/256. 6.? T. agapa, head of the holotype.