Thaumatomyrmex mandibularis

This rarely encountered ant is known only from Cuba. It is a specialist predator of polyxenid millipedes and forms very small colonies. It has been collected from leaf litter samples.

Identification
Baroni Urbani and de Andrade (2003) - Sharing with Thaumatomyrmex bariay the long mandibles and the marked body sculpture but differing from bariay by its larger size (TL > 4.87 mm instead of 4.20 mm), by the larger HW1 (CI1 > 133.7 instead of 126.3), by the longer mandibles (MI > 141.2 instead of 131.6), and by the longer scapes (SI > 88.2 instead of 84.2).

T. mandibularis appears to be the sister species of bariay. Both, bariay and mandibularis appear to be members of the cochlearis group as defined by Kempf (1975). This group previously containing only one species, Thaumatomyrmex cochlearis, possesses the following combination of characters: frons and vertex with posteriorly diverging rugulae and punctures, gular surface smooth and shining, thorax and petiole with punctures, mesonotum and propodeum continuous, without transversal notch, angle between basal and declivous propodeal faces obtuse, petiole cubiform, disc of clypeus without close-set setae. T. bariay, T. mandibularis, Thaumatomyrmex nageli, and T. cochlearis share all these characters. T. mandibularis and bariay differ from cochlearis and nageli by the longer mandibles and scapes.

T. mandibularis and T. bariay share with the members of the ferox group and with the subgroup 2 as defined by Kempf (1975) the head much broader than long and the mandibles at rest largely surpassing the genae laterally. T. mandibularis and T. bariay differ from the species of this subgroup 2 mainly by the head and mesosoma strongly sculptured instead of smooth and by the obtuse angle between the basal-and declivous propodeal faces.

Distribution based on Regional Taxon Lists
Neotropical Region: Cuba.

Nomenclature

 *  mandibularis. Thaumatomyrmex mandibularis Baroni Urbani & De Andrade, 2003a: 273, figs. 4, 5 (w.) CUBA.

Worker
TL 4.87-5.47; HL 0.85-0.95; HW1 1.14-1.30; HW2 1.03-1.15; EL 0.24-0.28; SL 0.75-0.87; ML 1.20-1.36; WL 1.36-1.48; PeL 0.51-0.55; PeW 0.64-0.73; HFeL 0.92-1.04; HTiL 0.81-0.92; HBaL 0.70-0.77; CI1 133.7-136.8; CI2 120.0-122.8; SI 88.2-91.6; MI 141.2-143.5.

Head anteriorly 1/4 broader than long and with the sides gently converging posteriorly. Vertexal margin weakly concave and carinate. Frontal lobes developed, largely surpassing the median clypeal border and slightly shorter than the lateral clypeal border. Median clypeal border straight. Eyes large, slightly less than 1/3 or more than 1/4 of the head length (mandibles excluded) and placed almost entirely on the anterior half of the head. Scapes shortly surpassing the vertexal margin. First funicular joint about 1/3 longer than broad. Joints 2-7 slightly broader than long, joints 8-10 slightly longer than broad and last joint slightly longer than the sum of joints 8-10. Basal teeth small or transformed in a minute swelling. Proximal teeth crossing each other on the clypeus. Intermediate teeth hidden apically by the frontal lobes. Apical teeth largely surpassing the maximum anterior head width and the eyes.

Mesosoma about 1/5 or 1/6 longer than the maximum head length (mandibles included). Mesonotum very short and only superficially differentiated from the propodeum in dorsal view. Propodeum gently convex in side view. Dorsal area between basal and declivous propodeal faces with traces of a superficial diverging margin. Petiole thick, about 1/4 broader than long. Petiole in side view with convex dorsum and truncate anterior and posterior faces. Petiole in dorsal view with gently concave anterior face and convex or diverging sides. Ventral process of petiole anteriorly with a subround tooth and posteriorly straight and minutely crenulated. First gastral tergite in dorsal view with perpendicular anterior face and with strongly convex sides.

Legs elongate. Hind tibiae about 1n or 1/8 shorter than the hind femora. Hind basitarsi about 1/6 shorter than the hind tibiae. Fore and hind tibiae with a pectinate spur each. Spurs of fore legs with a basal spine each. Mid tibiae with a small simple spur.

Sculpture. Anterior two thirds of the head dorsum covered with thin, longitudinal rugosities and sparse piligerous punctures, the rugosities slightly divergent and resembling irregular reticulation behind the frontal lobes and posterior border of the eyes. Posterior third of the head dorsum covered by variably impressed small reticulation, sometimes the reticulation sparse and resembling piligerous punctures mixed with very thin, sparse rugosities. Ventral face of the head smooth with very sparse, piligerous punctures on the genae. Mesosoma with dense, minute reticulation and piligerous foveae, the foveae sparse on the metapleurae and declivous face of the propodeum, rare on the mesopleurae. Center of the propodeum with very thin, short, transversal rugosities. Metapleurae with additional very thin, longitudinal rugosities. Declivous face of the propodeum with thin, transversal rugosities. Anterior half of the propleurae with additional, thin, longitudinal rugosities. Petiole with sparser and smaller piligerous punctures than on the mesosoma. Gastral tergites with anastomosing canaliculation and with very sparse piligerous foveae, the canaliculation denser on their sides. Legs minutely punctate.

Pilosity. Head, mesosoma, petiole and postpetiole with sparse subdecumbent or decumbent, truncate long hairs. Antennae and legs with appressed short hairs. Funicular joints, neck and antenna! fossae with very short, appressed hairs. Clypeus dorsally with two pairs of hairs close to the frontal lobes, the lower external pair longer.

Colour. Head, mesosoma, petiole and gaster black. Femora dark brown-black. Antennae, frontal lobes, mandibles and legs brown.

Type Material
Holotype and paratype. CUBA: Santiago Prov., Gran Piedra, Met. Radar, 6.XII.1995, 1100 m elfin, for. litter, 2 workers (holotype and paratype), 95-75 S. Peck ; 16.XII.l995, log & leaf litter, 1 worker, S. Peck [MCZC]; 9-12.XII.l995, leaf and log litter, 1 worker, S. Peck [MCZC].

Etymology
This species is named for its long mandibles, longest among Cuban Thaumatomyrmex.