Pristomyrmex elmesi

Known from the holotype.

Identification
Radchenko & Dlussky (2018) - Pristomyrmex elmesi differs from an other fossil species, Pristomyrmex rasnitsyni, by the somewhat smaller body (2.4 mm vs. 3 mm), by the slightly elongated, not transversal head (HL/HW 1.02 vs. 0.95), by the somewhat longer antennal scape (SL/HL 0.75 and SL/HW 0.77 vs. 0.72 and 0.68, respectively), by the much shorter, straight and thin propodeal spines (ESL/HW 0.12 vs. 0.25), by the absence of medial tooth on the anterior clypeal margin, by the another type of mandibular dentation, and by the longer mesosoma that is longer than head (in contrary, the mesosoma in P. rasnitsyni, is shorter than head).

By the character of mandibular dentation P. elmesi resembles modern Pristomyrmex bispinosus and Pristomyrmex trispinosus from Mauritius, by the absence of median tooth on the anterior clypeal margin it is similar to the species from the P. levigatus-group, and by the absence of frontal lobes it resembles species from the P. punctatus-group. Based on the combination of characters of both P. elmesi and P. rasnitsyni it is impossible to say anything about their relationship with any extant species or species-group of Pristomyrmex, but they do not seem more primitive compared to many modern species.

Distribution
This taxon was described from.

Nomenclature

 * † elmesi.  †Pristomyrmex elmesi Radchenko & Dlussky, 2018: 253, figs. 1-2 (w.) ROVNO AMBER.

Worker
HL 0.59, HW 0.57, FW 0.10, SL 0.44, OL 0.11, ML 0.66, MH 0.29, PL 0.24, PH 0.24, ESL 0.07, HTL 0.51. Ratios: HL/HW 1.02, SL/HL 0.75, SL/HW 0.77, OL/HL 0.18, PL/PH 1.13, PL/HL 0.41, ESL/HW 0.12, ML/MH 2.28.

Body length ca. 2.4 mm. Head somewhat longer than broad, with slightly convex sides, straight occipital margin and widely rounded occipital corners. Eyes well developed, strongly convex, almost rounded, situated at the midlength of sides of head. Anterior clypeal margin medially with two short lateral teeth and without central tooth. Frontal lobes vestigial, vertical, antennal sockets fully exposed, frons very narrow. Antennae 11-segmented, with distinct 3-segmented apical club; scape sharply angled at base, quite long, almost reaching occipital margin. Man dibles elongate-triangular, their masticatory margin with sharp and relatively long apical tooth, sharp but shorter preapical tooth, two blunt and minute denticles, long diastema, and triangular basal denticle. Palp formula seems 3, 2.

Mesosoma relatively long, 1.12 times longer than head and 2.28 times longer than height, promesonotum narrowed posteriorly, with narrowly rounded humeri and slightly convex anterior margin. Metanotal groove obscured, but most probably present.

Propodeum with rather short, straight, thin, acute spines directed rather upward than backward at an angle ca. 60o. Pronotum without spines or teeth. Petiole with long peduncle and strongly concave anterior surface, its node quite high, with rounded dorsum. Postpetiole higher than long, with rounded dorsum. Middle and hind tibiae without spur.

Head and mesosoma with very coarse reticulation. Central part of clypeus smooth. Petiole and postpetiole smooth. Head and mesosoma with sparse long thin hairs, anterior clypeal margin with eight long setae; petiole, postpetiole and gaster without hairs; femora ant tibiae with short and not abundant subdecumbent hairs, tarsi with sparse and quite long hairs.

Type Material
Holotype, worker, No. K-7248, Rovno amber, Late Eocene, Ukraine.

Etymology
The species is dedicated to the memory of well-known British myrmecologist and our friend, Dr. Graham Wakely Elmes (1943–2017).