Eocenomyrma breviscapa

Radchenko, A. G. & Dlussky, G. M., 2016, Further Data On The Extinct Ant Genus Eocenomyrma (Hymenoptera, Formicidae), Vestnik Zoologii 50 (5), pp. 395-406 : 400-405

Eocenomyrma breviscapa sp. n.

M a t e r i a l e x a m i n e d. Holotype, worker, SIZK K-5518 , Klesov , Rovno amber, Late Eocene.

E t y m o l o g y. From the Latin words “ brevis ” — short, and “ scapus ” — scape, meaning that the antennal scape is short.

W o r k e r ( figs 7–11 ). Total length ca. 2.4 mm. Head short, 1.07 times longer than width, with convex sides, rounded occipital corners and convex occipital margin. Eyes of moderate size, their maximum diameter 0.21 of head length, situated at midlength of lateral sided of head. Antennae 12-segmented, with distinct, quite big 3-segmented club that is subequal to total length of remainder funicular segments, first funicular segment ca. 1.5 times longer than width, 2–8th segments transversal; scape very short, nearly twice shorter than head length, far not reaching occipital margin. Central part of clypeus longitudinally concave, with two lateral longitudinal carinae and well marked anterolateral corners, its anterior margin concave, with pair of long setae on anterolateral corners. Clypeus posteriorly widely inserted between frontal lobes; frontal lobes anteriorly reaching anterior clypeal margin. Palp formula 4, 3. Mandibles elongate-triangular, masticatory margin with longer apical tooth and small 5 denticles.

Mesosoma ca. 2.8 times longer than height, promesonotal suture developed, metanotal groove deep. Anterior margin of pronotum slightly convex, humeri narrowly rounded. Propodeal spines rather short, straight, widened at base and acute at apex, directed posteriorly at an angle ca. 45 o (seen in profile), very slightly divergent (seen from above). Propodeal lobes rounded. Petiole with very short peduncle, quite high, only little longer than height, its anterior surface steep, very slightly concave, meets with dorsal surface of node at an acute angle, dorsal plate short ant strongly declined posteriorly so that petiole seems cuneiform (seen in profile). Postpetiole wider than petiole. Middle and hind tibiae without spur.

Head dorsum, mesosoma and waist densely punctated, head dorsum additionally with longitudinal striation.

Body with sparse, rather short, blunt straight suberect hairs, scape and legs with decumbent pilosity.

Measurements (in mm): HL 0.62, HW 0.57, FW 0.17, FLW 0.18, SL 0.33, OL 0.13, PnW 0.36, ML 0.74, MH 0.30, PL 0,22, PW 0.23, PH 0.20, PPL 0.09, PPW 0.27, PPH 0.20, ESL 0.09, ESD 0.20, HTL 0.33, total length ca. 2.4.

Indices: HL/HW 1.09, FW/HW 0.30, FLW/FW 1.08, SL/HL 0.52, SL/HW 0.57, OL/HL 0.21, PL/HL 0.35, PL/ PH 1.13, PPL/HL 0.15, PPL/PPH 0.47, ESL/HL 0.15, ESL/HW 0.16, ESD/ESL 2.14, ML/MH 2.48.

G yn e s an d mal e s un know n.

C o m p a r a t i v e d i a g n o s i s. E. breviscapa well differs from all known Eocenomyrma species (including described here gyne of E. ukrainica ) by the punctated head, mesosoma and waist, by the much shorter, cuneiform petiole (PL/ PH 1.13 vs.> 1.25 in other species), by the shorter propodeal spines (ESL/HW 0.16 vs.> 0.30 in other species), and by the distinctly shorter scape (SL/HL 0.52 vs.> 0.58, usually> 0.60 in other species).

Figures

Figs 7–8. Eocenomyrma breviscapa sp. n., photos of holotype worker: 7 — body in dorsal view; 8 — body in lateral view. Scale bar 1 mm.

Figs 9–11. Eocenomyrma breviscapa sp. n., line drawings of holotype worker made based on photos: 9 — body in dorsal view; 10 — body in lateral view; 11 — head in dorsal view (sculpture omitted). Scale bar 1 mm.