Platythyrea pumilio

A Dominican amber fossil ant.

Identification
De Andrade (2004) - Known from the worker only, sharing characters with the workers of Platythyrea scalpra and Platythyrea exigua, but differing from both by the declivous propodeal sides lamellaceous and by the much less pronounced postero-median petiolar convexity, from scalprum only by the head narrower and by the petiole shorter and higher, and from exigua only by the fore femora broader, by the lack of metacoxal tooth and by its smaller size.

P. pumilio, described in this paper, and scalprum are the smallest Platythyrea known to date from the New World. P. pumilio shares with the Dominican fossil P. scalprum the fore basitarsi with a seta opposite the strigil and the swollen fore femora, but it differs from it mainly by the petiole shorter and higher and by the head much narrower. P. pumilio shares with the Brazilian P. exigua the head elongate and narrow with flat eye on the anterior half of the head and by the rnasticatory margin of the mandibles minutely denticulate. P. pumilio differs from the Brazilian exigua mainly by its lack of metacoxal teeth, by it fore femora broader, and by its posterior petiolar face unarmed. P. pumilio shares with the Ecuadorian zodion a similar petiolar shape, but it differs from it by the head much longer and by the size smaller. P. pumilio shares with the other Dominican fossil. P. procera the propodeal declivity with a lamella and the lack of metacoxal teeth. P. pumilio differs from procera mainly by its smaller size.

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

Nomenclature

 * † pumilio. †Platythyrea pumilio De Andrade, 2004: 644 (w.) DOMINICAN AMBER.

Worker
TL 3.82: HL 0.75; HW 0.46; EL 0.18; SL 0.44; WL 0124; PeL 0.45; HFeL 0.59; HTiL 0.57; HBaL 0.41; FFeL (left) 0.54; FFeW (left) 0.25, FFeL (right) 0.59; FFeW (right) 0.25; CI 61.3; SI 58.6; FFeI (left) 46.3; FFeI (right) 42.5.

Head elongate, slightly less than 2/3 longer than broad, with subparallel sides. Vertexal margin medially concave. Venexal angle lightly protruding posteriorly and subround. Frontal lobe far from each other and gently rounded. Clypeus declivous anteriorly, with truncate anterior border and weakly differentiated from the frontal lobes posteriorly. Eyes large, about 1/4 of the head length and placed dorsolaterally on the anterior half of the head. Mandible subtriangular. Masticatory margin of the mandibles with 7-8 minute irregular denticles followed by an apical one. Mandibular sulcus supertfcially impressed. Palpal formula 3,2, the mandibular palp not surpassing the postero-medial rim of buccal cavity. Scapes much shorter than the vertexal margin. First funicular joint lightly longer than broad. Funicular joints 2-10 lightly broader than long. Last funicular joint about as long as the sum of joints 9-10.

Mesosoma in profile elongate. Pronotum in dorsal view with barely distinguishable humeri. Pronotal suture impressed. Posterior third of the propodeal dorsum gently declivous posteriorly. Sides between basal and declivous propodeal faces subround. Sides of the declivous face with a lamella reaching the propodeal lobes.

Petiole longer than broad. Anterior face of the petiole in dorsal view weakly convex medially and weakly angulated latero-ventrally. Posterior face of the petiole in dorsal view poorly convex medially and unarmed laterally. Postpetiole slightly shorter than first gastric segment.

Fore femora strongly incrassate. Fore basitarsi with a seta opposite to the strigil. Hind tibiae slightly shorter than hind femora. Hind basitarsi slightly shorter than 1/3 of the tibiae. Mid and hind tibiae with paired, pectinate spurs. Tarsal claw with preapical teeth.

Sculpture. Integument opaque. Head, mesosoma, petiole, postpetiole and gaster densely and finely reticulate-punctate and with sparse, minute, superficial foveae. Legs minutely punctate, the punctures more superficial than in the other body parts.

Body densely covered by very short, thin hairs. Apex of the gaster with long hairs.

Colour. Light brown.

Type Material
Holotype worker from Dominican amber, labelled: MCZC-37 in the. A small dark orange sample 1.1 x 0.8 cm containing a worker of Platythyrea and impurities. The preservation condition of the ant is good.

Etymology
From the Latin substantive pumilio = dwarf, pygmy, referring to the small size of this species. It is used here as a noun in apposition.