Tyrannomyrmex dux, Borowiec, Marek L., 2007

Borowiec, Marek L., 2007, A new species of Tyrannomyrmex (Hymenoptera: Formicidae: Myrmicinae) from India, Zootaxa 1642, pp. 65-68 : 66-68

Tyrannomyrmex dux sp. n.

( Figs. 1–4 )

Worker measurements: HW 0.52, HL 0.71, EL 0.0 5, SL 0.56, PrW 0.49, WL 1.0 3, PL 0.39, PPL 0.21, PW 0.22, PPW 0.31, GL 0.77, TL 3.11, CI 73, SI 107.

General appearance as in Fig. 1 . Head longer than wide, sides and posterior outline slightly convex. Posterior head corners rounded. Mandibles triangular, masticatory margin edentate except two blunt apical teeth. Palp formula undeterminable. Clypeus convex in anterior part, posteriorly narrowly inserted between frontal lobes. Clypeus lacking carinae. Frontal lobes present and short but prominent, rounded and obscuring antennal sockets. Antennae 11-segmented with feebly defined three segmented club, apical segment being largest and equal in length to rest of funiculus, excluding pedicel. Scape slightly longer than head width, shallowly curved at base. Eyes small, composed of a few feebly defined ommatidia and situated slightly anterior to midlength of head (at 45% of HL).

Mesosoma devoid of any kind of grooves or sutures, in side view forming a single broad and continuous convexity. In dorsal view it is widest in promesonotal area, slightly decreasing in width posteriorly. Anteroventral corner of pronotum rounded. Propodeal spiracle round and situated at distance about 3,5 diameters from propodeal margin. Propodeum armed with two very small, triangular, and acute teeth. Metapleural lobes broad, more or less rounded. Metapleural gland orifice not seen at 110X. Petiole without clearly differentiated node or peduncle, node lower than long, in dorsal view longer than wide. Postpetiole wider than long; postpetiolar sternite with transverse keel anteriorly, forming acute tooth in lateral view.

Head and mesosoma heavily foveate. Foveae dense, irregular, usually less than 1/3 their diameter apart. Interspaces between foveae smooth and shining on head, sides of promesonotum and dorsal surface of mesosoma; those on katepisternum and sides of propodeum very feebly shagreened, appearing matt. Sculpture of petiole consisting of microreticulum in most of anterior part and irregular foveae on postero-dorsal surface. Sculpture of postpetiole microreticulate. Gaster covered with microreticulum fading before half length of first gastral tergite, remainder of gaster smooth.

Body pilosity dense and abundant, composed of many erect hairs present on the head, meso- and metasoma; hairs on head and mesosoma arising from centers of foveae. Abundant hairs also present on body appendages, being present on antennal scape as well as funiculus; hairs present on all leg segments and on both dorsal and ventral surfaces of mandibles; those on ventral surface not differing visibly in structure from rest of pilosity. Body color reddish, appendages yellowish.

Holotype deposited in the Department of Biodiversity and Evolutionary Taxonomy, Zoological Institute, University of Wroclaw, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland.

Holotype worker bears the following labels: white printed label ‘S-INDIA, Kerala state, Ponmudi hill resort, 30 km NE of Trivandrum, 77°06'E 8°46'N, ca 1300-1500m, 28-30.vi.1999, Z. Kejval & M. Trýzna leg.’ and red, printed, edged in black, label ‘ HOLOTYPUS Tyrannomyrmex dux des. M. L. Borowiec 2007’.

Diagnosis. T. dux is most easily distinguished from T. rex by the differences in pilosity, sculpture and the shape of the petiole. T. rex is almost lacking pilosity on the mesosoma, while its whole surface is covered with erect hairs in T. dux . Also the sculpturation is stronger in T. dux , especially on the mesosoma. While in T. rex foveae on the mesosoma are small with most interspaces equal or wider than their diameter, T. dux has them deeper, larger, irregular and almost touching each other. Also, the petiole in T. rex is stout with a big node and short peduncle, while in T. dux the node is more slender, much lower than long ( Fig. 4 ).

Discussion. Fernández (2003) listed the following character combination as unique to Tyrannomyrmex :

1) Mandibles with two teeth in the masticatory border, apical and smaller subapical.

2) Inner ventral margin of masticatory border of mandibles with modified thick, cylindrical and transparent setae.

3) Clypeus not modified as central plate and devoid of carinae.

4) Anterior clypeal margin with single median seta.

5) Palpal formula apparently 2,2.

6) Antennae 11-segmented with ill-defined 3-segmented club.

7) Compound eyes small, reduced to a few ommatidia.

8) Frontal carinae and antennal scrobes absent.

9) Mesosoma without grooves.

10) Propodeal spiracle round.

11) Propodeal lobes large.

12) Sting large and robust.

Tyrannomyrmex dux agrees well with this diagnosis, but the setae on the venter of the mandibles (2) appear simple, not modified, and similar in structure to other setae of body. Though the sting is also extruded in T. dux , it is not as long as in T. rex (12). Palp formula (5) could not be determined reliably. Thus at least characters 2) and 12) are not universal throughout Tyrannomyrmex .

Formal placement of the genus in any tribe should be postponed until examination of other castes and more worker material is available allowing dissections.

Figures

FIGURES 1 – 4. Tyrannomyrmex dux sp. n., holotype worker; 1: lateral body; 2: dorsal body; 3: frontal head; 4: lateral waist.