Eocenomyrma ukrainica, Radchenko & Dlussky, 2016

Radchenko, A. G. & Dlussky, G. M., 2016, Further Data On The Extinct Ant Genus Eocenomyrma (Hymenoptera, Formicidae), Vestnik Zoologii 50 (5), pp. 395-406 : 396-400

Eocenomyrma ukrainica sp. n.

M a t e r i a l e x a m i n e d. Holotype, male, SIZK K-3076 , and paratype, gyne, SIZK K-27012 , both from Klesov , Rovno amber, Late Eocene.

E t y m o l o g y. Named after Ukraine, country where the type material of this species was found.

M a l e ( figs 1–4 ). Total length: ca. 2.45 mm. Head distinctly longer than width, with convex sides, moderately rounded occipital corners and quite strongly convex occipital margin. Clypeus convex (seen in profile), with two not coarse lateral carinae, its anterior margin shallowly and widely concave. Eyes not very big, their maximal diameter about 3 times smaller than length of head, situated distinctly in front of midlength of sides of head, so that temples longer than maximum diameter of eye. Ocelli well developed though not big. Antennae 13-segmented, with not well defined 3-segmented club, scape of moderate length, far not reaching occipital margin, subequal to total length of 1st to 5th funicular segments. Mandibles elongate-triangular, with distinct masticatory margin, which is with four small acute teeth. Palp formula 4, 3.

Mesosoma relatively long, scutum not strongly convex, Mayrian furrows well developed. Propodeum with distinct short acute teeth, its dorsal surface subequal to posterior one. Petiole and postpetiole barely visible, but petiole seems with quite short peduncle and high node with rounded dorsum; postpetiole higher than length, with rounded dorsum. Middle and hind tibiae without spurs, pretarsal claws simple.

Forewing venation rather peculiar: veins are very coarse, closed cell 1r+2r long and marrow, and closed cell mcu extremely small (especially on left wing). Except for those, general character of venation similar to that of gyne (see below).

Head dorsum finely but densely punctated, frons laterally with fine longitudinal rugulae, narrow central band on frons between frontal triangle and anterior ocellus, as well as frontal triangle and central part of clypeus, smooth and shiny; mandibles with fine longitudinal rugulosity, appear shiny. Pronotum with very fine transversal striae, anterior part of scutum between Mayrian furrows with fine superficial microstriation, its remainder part and scutellum smooth and shiny. Mesopleura and sides of propodeum with somewhat coarser longitudinal rugulosity. Gaster smooth and shiny.

Whole body with not abundant, rather short suberect hairs; scape and legs with sparse decumbent pilosity.

Measurements (in mm): HL 0.53, HW 0.45, SL 0.27, OL 0.19, ML 0.75, MH 0.43, HTL 0.40, total length ca. 2.45.

Indices: HL/HW 1.18, SL/HL 0.50, SL/HW 0.59, OL/HL 0.35, ML/MH 1.75.

G y n e ( figs 5 , 6 ). Total length ca. 3 mm. Head width is not properly measurable, but head seems elongate, with almost straight sides, rounded occipital corners and slightly convex occipital margin. Eyes of moderate size, situated in front of midlength of sides of head, length of genae subequal to maximum diameter of eye. Ocelli rather small. Antennae 12-segmented, with 3-segmented club, first funicular segment ca. twice longer than width, 2nd to 8th segments somewhat longer than width; scape relatively short, not reaching occipital margin. Clypeus with two lateral carinae, anterior clypeal margin shallowly and widely concave. Mandibles obscured in the specimen.

Mesosoma relatively short, less than 1.5 times longer than height, scutum slightly convex, does not overlap pronotum. Propodeum with quite long thin, not widened at base acute spines, its dorsal surface somewhat shorter than posterior one, propodeal lobes angulated at apices, but not sharply pointed. Petiole long and quite low, with long peduncle, ca. 1.8 times longer than height, its anterior surface distinctly concave, petiolar node with very narrowly rounded dorsum, almost cuneiform. Postpetiole subdlobular. Spur on middle tibia obscured, but hind tibiae with small simple spur.

Forewing with closed cells 1r+2r and mcu, cell 3r open posteriorly, cell rm absent; cell 1r+2r very long, ca. twice longer than width. Vein section 1RS slightly inclined posteriorly. Cell mcu trapezoid (not pentagonal), far not reaching distally level of pterostigmal base. Cross-vein cu-a merging with vein section 1M+Cu far proximally than cell mcu (vein section 2M+Cu much longer than cross-vein cu-a).

Head dorsum with not coarse but dense longitudinal, slightly sinuous rugosity, reticulation developed on sides of head and on occipital region. Pronotum with five transversal rugae, scutum and scutellum with finer, dense longitudinal rugae, mesopleura and sides of propodeum with coarser longitudinal, slightly sinuous rugae. Petiole densely and quite coarsely punctated, postpetiole with les coarse punctation.

Whole body with not abundant straight erect to suberect hairs; scape and legs with short subdecumbent pilosity.

Measurements (in mm): HL 0.65, SL 0.43, OL 0.13, ML 0.75, MH 0.51, ScW 0.45, PL 0.32, PH 0.18, PPL 0.19, PPH 0.19, HTL 0.40, ESL 0.11, total length ca. 3.00.

Indices: SL/HL 0.65, OL/HL 0.20, PL/HL 0.49, PL/PH 1.79, PPL/HL 0.29, PPL/PPH 1.00, ESL/HL 0.17, ML/MH 1.47.

Workers unknown.

C o m p a r a t i v e d i a g n o s i s. We may compare only gyne of E. ukrainica with the workers of other species because males of other species are unknown. Gyne of E. ukrainica well differs from E. breviscapa sp. n. by the another sculpture (notpunctated) of the head, mesosoma and waist; it differs from E. elegantula Dlussky et Radchenko by the mostly longitudinally rugulose sculpture on the head and mesosoma instead the fine and dense reticulation in the latter species; from E. electrina Dlussky et Radchenko it differs by the distinctly longer petiole (PL/PH 1.79 vs. 1.27), by the much shorter, straight propodeal spines (ESL/ HL 0.17 vs. 0.33), by the sculpture of the mesosoma (mostly longitudinally rugose vs. completely coarsely reticulated in the latter species). Similarly to the preceding species, E. ukrainica differs from E. orthospina Dlussky et Radchenko by the shorter propodeal spines (ESL/HL 0.17 vs.> 0.35) and by the similar pattern of the mesosomal sculpture. At last, by the body sculpture E. ukrainica the most resembles E. rugosostriata (Mayr), but duffers from it by the distinctly shorter and straight propodeal spines (ESL/HL 0.17 vs.> 0.30).

Figures

Figs 1–2. Eocenomyrma ukrainica sp. n., photos of holotype male: 1 — body in dorsal view; 2 — head in dorsal view. Scale bar 1 mm.

Figs 3–4. Eocenomyrma ukrainica sp. n., line drawings of holotype male made based on photos: 1 — body in dorsal view; 2 — head in dorsal view (sculpture omitted). Scale bar 1 mm.

Fig. 5. Eocenomyrma ukrainica sp. n., photo of paratype gyne, body in lateral view. Scale bar 1 mm.

Fig. 6. Eocenomyrma ukrainica sp. n., line drawing of paratype gyne made based on photo, body in lateral view (sculpture omitted). Scale bar 1 mm.