Cylindromyrmex antillanus

A Dominican amber fossil species known only from the queen caste.

Identification
De Andrade (1998) - A member of the longiceps clade. A species resulting as outgroup of Cylindromyrmex longiceps and Cylindromyrmex meinerti, and differing from both for the CI > 77 (instead of ≤ 70) and HFeI < 46 (instead of > 50).

C. antillanus, Cylindromyrmex longiceps and Cylindromyrmex meinerti share the narrow frontal carinae, the eye on the middle of the sides of the head, the mesosoma 2/3 longer than high, and the petiole with a short anterior face. The workers of longiceps and meinerti possess reduced and flat eyes. It is likely that the unknown worker of antillanus also has similar eyes.

Distribution
This taxon was described from Dominican Amber (Miocene).

Nomenclature

 * † antillanus. †Cylindromyrmex antillanus De Andrade, 1998a: 639, figs. 1, 28 (q.) DOMINICAN AMBER (Miocene).

Queen
TL 6.36; HL 1.08; HW 0.84; EL 0.35; SL 0.32; SW 0.15; WL l.68; PeL 0.524; PeW 0.56; HFeL 0.53; HFeW 0.24; HTiL 0.44; HTiW 0.16; HBaL 0.25; HBaW 0.07; CI 77.8; SI 46.9; HFeI 45.3; HTiI 36.4; HBaI 28.0.

Head slightly less than 1/3 longer than broad. Occiput low. Vertexal angles convex. Frontal carinae about 1/3 broad as the maximum head width. Sides of the frontal carinae parallel and reaching at least the middle of the eyes posteriorly. Dorsum of the frontal carinae with an impressed median sulcus anteriorly. Frontal carinae as long as the anterior border of the clypeus. Antero-median border of the clypeus with a minute pair of denticles. Compound eyes large, flat and on the middle of the head. Impar ocellus developed. Scapes reaching the anterior border of the eyes. Proximal third of the scapes ½ narrower than the distal parts. Mandibles gently convex dorsally. Masticatory margin of the mandibles each with a set of 4 irregular denticles followed by an apical tooth.

Mesosoma slightly convex dorsally. Pronotum with parallel sides. Parapsidal furrows superficially impressed. Propodeum with the sides gently convex and converging posteriorly. Basal face of the propodeum separated from the declivous one by a thin margin.

Petiole subquadrate, slightly broader than long, anteriorly truncate and dorsally gently convex. Petiolar sides diverging backwards. Ventral process of the petiole large and subround. Postpetiolar sides gently diverging posteriorly. Postpetiolar sternites antero-medially with a marked, triangular “lip” pointing backwards. Pygidium in side view truncate. Posterior half of the pygidium in full dorsal view with the sides bearing a row of small denticles converging to a deep notch.

Legs. Femora and tibiae slightly inflated. Hind basitarsi short, slightly less than 1/3 shorter than the maximum length of the tibiae. Outer apical edge of the hind and of the mid basitarsi respectively with 3,5 spine-like setae.

Sculpture. Head covered by thin, longitudinal striae, slightly thicker on the posterior third of the head dorsum. Mesosoma longitudinally striated. Dorsum of the pronotum with about 30 longitudinal striae similar to those on the posterior part of the head dorsum: some pronotal striae bifurcated. Mesonotum and propodeum covered by longitudinal striae thinner than those on the pronotum. Scutellum. pleurae, declivous face of the propodeum, petiolar sides and ventral face of mid and hind femora with very thin, longitudinal striae, thinner on the scutellum, propleurae. petiolar sides and mid femora. Petiolar dorsum with about 28 striae similar to those on the propodeum. Anterior face of the petiole smooth. Dorsum of the postpetiole densely covered by striae as those on the petiole. First gastric tergite with thin, superficial, longitudinal striae on the center only. Second gastric culptured as the first tergite but the striae extremely thin. Postpetiolar sternites, remaining gastric segments and legs smooth and with sparse punctures. Hind coxae covered by thin, longitudinal striae; mid coxae with similar sculpture but sparser and fainter.

Pilosity. Body with pointed hairs of at least three lengths and distributed as follows: (1) long, erect to suberect, one on the external border of the scape, a pair between the frontal carinae and clypeus, rare on the mandibles, on the mesosoma, on the gaster and on the legs, sparse on the pygidium; (2) shorter than the type (1) and sparsely distributed on the whole body; (3) shorter than the type (2), suberect on the head dorsum and mesosoma, subdecumbent on the pedicel, decumbet on the ventral part of the head, on the gaster and on the legs. In addition, the hypostomal bridge surrounded by a layer of hairs similar to the type (1) but appressed and apically curved.

Colour dark brown. Tibiae yellowish to light brown.

Type Material
Holotype: Winged gyne in the amber sample. Do-4130-1 from the.

Etymology
The name antillanus is a neologism indicating the provenance of this amber sample from the Antilles.