Promyopias Santschi

Bolton, Barry & Fisher, Brian L., 2008, Afrotropical ants of the ponerine genera Centromyrmex Mayr, Promyopias Santschi gen. rev. and Feroponera gen. n., with a revised key to genera of African Ponerinae (Hymenoptera: Formicidae), Zootaxa 1929, pp. 1-37 : 28-30

Promyopias Santschi gen. rev.

Promyopias Santschi, 1914: 323 [as subgenus of Myopias by Forel, 1917: 238; as subgenus of Pseudoponera by Wheeler, W.M. 1922: 649. Raised to genus by Emery, 1915: 26; Santschi, 1924: 158. Provisional synonymy with Centromyrmex by Brown, 1973: 184; synonymy with Centromyrmex by Bolton, 1994: 164.] Type-species: Myopias (Promyopias) silvestrii Santschi, 1914: 324 , by monotypy. Gen. rev.

DIAGNOSIS OF WORKER AND QUEEN (gyne)

A monotypic Afrotropical genus.

1 Mandible elongate and narrow (MI 55–60 in worker). Apex of mandible armed with a short vertical series of 3–4 small teeth (may be worn and indistinct). Apical half of inner margin of mandible concave. Basal angle of mandible at about the midlength of the inner margin (where a small tooth is present) and proximal of this the long basal margin is shallowly convex. A weak basal groove present but without a dorsal longitudinal groove and without a basal pit.

2 Palp formula 4,4.

3 Median portion of clypeus projects slightly anteriorly, its anterior margin transverse.

4 Frontal lobes with their anterior margin close to, but not overhanging, the anterior clypeal margin; in full-face view the distance from the most anterior point of a frontal lobe to the anterior clypeal margin is about equal to the basal width of the scape.

5 Eyes absent in worker, present in queen.

6 Antenna with 12 segments; scape somewhat dorsoventrally flattened; funiculus gradually incrassate towards the apex but without a strongly differentiated club.

7 Frontal groove on mid-dorsum of head extends far posterior of the terminus of the frontal lobes.

8 Pronotum bluntly and obtusely marginate anteriorly and laterally.

9 Mesopleuron without a transverse suture that divides the sclerite into anepisternum and katepisternum.

10 Metanotal groove (worker only) vestigial to moderately developed in dorsal view; in profile the propodeum continues the line of the mesonotum.

11 Orifice of metapleural gland a posteriorly directed curved slit that is shielded from lateral view by a small lobe of cuticle, the orifice about level with the upper portion of the propodeal lobe.

12 Metasternal process present as a pair of distinctly separated triangular long teeth that are slightly divergent and slightly curved posteriorly; metasternal pit is between the teeth.

13 Propodeum unarmed, weakly bilaterally compressed in dorsal view so that propodeal dorsum is narrower than mesonotum.

14 Propodeal spiracle broadly elliptical, almost round, low on the side and at about the midlength of the sclerite, abutting the metapleural gland bulla.

15 Propodeal lobes bluntly triangular and prominent.

16 Procoxa not hypertrophied but larger than the mesocoxa and metacoxa.

17 Mesotibia, mesobasitarsus and metabasitarsus with strongly sclerotised spiniform traction setae; such setae absent from metatibia.

18 Mesotibia and metatibia each with two spurs, the anterior small and simple, the posterior larger and pectinate.

19 Pretarsal claws small, simple.

20 Petiole in profile without an anterior peduncle.

21 Subpetiolar process low, anterior and roughly broadly triangular.

22 Helcium located close to mid-height on anterior face of the first gastral segment (abdominal segment III).

23 Prora a longitudinal, thick, bluntly convex crest that extends from just below the helcium almost to the apex of the first gastral sternite.

24 Girdling constriction between presclerites and postsclerites of second gastral segment present but shallow.

25 Stridulitrum absent.

26 Queen only (dealate). Moderately large eyes and conspicuous ocelli present. Mesosoma with full complement of flight sclerites. Transverse suture absent from mesopleuron (as in worker).

Discussion of female characters

Apomorphic characters, in italics above, include 1, 4 and 23. Characters 1–25 together form an inclusive diagnosis that isolates Promyopias workers and queens from all other genera in the tribe.

1 Elongate narrow mandibles that are linear to curvilinear have evolved independently several times in Ponerini . Often the narrowed mandible is universal in a genus (e.g. Harpegnathos , Odontomachus , Anochetus , Plectroctena , Myopias , Boloponera ) but sometimes it is developed in some species groups of a genus but not others (e.g. Leptogenys stuhlmanni group and L. maxillosa group, Pachycondyla agilis group). In each case the detailed mandibular morphology, while consistent within a group, differs from that of other groups, which strongly suggests separate evolutions. The structure in Promyopias shows equally elongate but discernible basal and apical sections that are still quite distinct as the inner margin of the apical section is concave while the basal section is convex; the detailed structure here is unique.

2 PF 4,4 is the plesiomorphic maximum count for workers and queens in tribe Ponerini ( Brown, 1963; Bolton, 2003).

4 In the sequence Centromyrmex – Promyopias – Feroponera the anterior margins of the frontal lobes draw closer to the anterior clypeal margin. In the first the anterior margins of the frontal lobes are plesiomorphically well posterior of the anterior clypeal margin, in the second quite close and in the third slightly overhanging the clypeal margin.

5 The loss of eyes in the worker caste but not in queens is also characteristic of Centromyrmex : see discussion of potential genus group, below.

6 The scape is broad in dorsal view and somewhat dorsoventrally flattened, but by no means as strongy flattened in its basal half as in Centromyrmex .

10 A discernible metanotal groove, that runs uninterruptedly across the entire dorsum of the mesosoma in workers, is variably developed. In two specimens the groove was vestigial, in three moderate and in one quite distinct.

11 Orifice of the metapleural gland is located normally here, close to the posteroventral corner of the mesosoma.

12 A bidentate to bispinose metasternal process is usual in Ponerini .

17 The presence and distribution of spiniform setae is duplicated in Centromyrmex and Feroponera : see discussion of potential genus group, below.

18 This distribution of tibial spurs is certainly plesiomorphic in Ponerini as a whole; it is the basal condition from which all tibial spur modifications within the tribe have been derived.

22 Position of the helcium is similar in Centromyrmex and Feroponera : see discussion of potential genus group, below.

23 The development of the prora in Promyopias appears unique in Ponerini .

Comment

Santschi (1914) initially associated Promyopias with Myopias , the latter a moderately sized genus (34 described species) widespread in the Oriental, Malesian and Austral regions, because of supposed overall similarities in the form of the mandible and clypeus. It now seems certain that these similarities are the result of convergence through the development of similar predatory behaviours and life styles in the two genera. Major characters of Myopias that differentiate it from Promyopias include: eyes usually present in worker (absent in one species); scape not flattened; mesonotum sharply defined; spiniform setae entirely absent from middle and hind tibiae and basitarsi; helcium located at base of first gastral segment; posterodorsal margin of helcium with a median emargination; prora an anteroventral tooth; stridulitrum present.

During its history Promyopias has been regarded as a separate genus or as a subgenus of two other ponerine genera. The provisional synonymy of Promyopias with Centromyrmex proposed by Brown (1973) and accepted by Bolton (1994, 2003) was based on the presence and distribution of spiniform setae on the legs. It is now apparent that this decision was incorrect and Promyopias is formally reinstated at genus-rank here.