Simopone rex

Collected from low vegetation, a tree stump, foraging on the ground and from a dead twig above the ground in various forest habitats.

Identification
A member of the emeryi species group. S. rex is one of a complex of five large, stocky, size-variable Madagascan species that are quickly distinguished from all others in the region by their abundant pilosity. In particular, the tergites of AII to AIV have numerous curved setae that arise over the entire surface of each sclerite. These setae, while not particularly long, are dense, curved posteriorly, suberect to subdecumbent and very conspicuous. In addition, the sternites of AII and AIV have similar setae which, while not usually as numerous as on the tergites, are also very distinct. Of the five, Simopone victrix alone has very dense, small punctures all over the tergites of AV and AVI; the other species have sparse, scattered punctures on these tergites. S. rex and Simopone silens have a conspicuous longitudinal carina on the side of AII tergite. Also in these two the posterior corners of AII are rounded, not extended into sharp angles or posterolaterally projecting teeth, and the frontal carinae are relatively short. In Simopone dux, Simopone sicaria and victrix there is no carina along the side of AII, or at most there may be a minute vestige of it close to the anterior margin. In dux the dorsal outline of the pronotum in profile is distinctly humped or swollen, while in the other species it is shallowly convex along its length. (Bolton and Fisher 2012)

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  rex. Simopone rex Bolton & Fisher, 2012: 60, figs. 64-66 (w.) MADAGASCAR.

Worker
(holotype in parentheses). HL 2.10–2.36 (2.24), HW 1.88–2.18 (2.01), SL 0.84–0.94 (0.94), EL 0.58–0.64 (0.64), PW 1.40–1.58 (1.54), AIIW 1.28–1.45 (1.36), AIIL 1.12–1.32 (1.18), AIIIW 1.58–1.84 (1.66), AIIIL 1.36–1.60 (1.44), WL 2.56–2.88 (2.64), MFL 1.76–2.08 (1.92), CI 85–92 (90), SI 43–47 (47), EL/HW 0.30–0.33 (0.32), EP 1.15–1.31 (1.25), AIIW/AIIL 1.10–1.16 (1.15), AIIIW/AIIIL 1.06–1.17 (1.15) (9 measured).

In full-face view anteriormost points of frontal lobes are slightly posterior to the level of the midpoint of the shallowly convex anterior clypeal margin. With head tilted slightly back from full-face view the clypeal margin in front of the antennal socket extends into a blunt triangular prominence that projects farther forward than the midpoint of the anterior clypeal margin. Frontal carinae relatively short; in full-face view terminating in front of the level of the anterior margins of the eyes. Eyes located behind the cephalic midlength (EP 1.15–1.31). Leading edge of scape with conspicuous projecting setae. In full-face view entire side of head with setae that are curved anteriorly. In profile entire dorsum of head, and ventral surface, with curved standing setae. Cephalic dorsum between eyes with sparse foveolate punctures. Anterior and dorsal surfaces of pronotum separated by an angle or weak margination, but without a strongly defined carina. Propodeal dorsum meets declivity through a blunt angle, without a transverse carina. Propodeal declivity without longitudinal striolae that radiate upwards from the foramen in which AII (petiole) is inserted. Promesonotal suture weakly impressed and distinguished by a series of minute ribs or aligned punctures; metanotal groove very faint but median pit conspicuous. Mesosoma in dorsal view broadest across pronotum, narrower across mesonotum and propodeum (in holotype PW 1.54, width across mesonotum at its midlength 1.25, maximum width across propodeum 1.35). Dorsum of mesosoma with scattered punctures. Entire mesosoma dorsally with numerous standing setae. Dorsal (outer) surfaces of mesotibiae and metatibiae with standing setae present that are curved or inclined toward the apex. Dorsal surface of AII (petiole) meets anterior surface in an angle, without a transverse carina. Posteriorly the dorsum of AII lacks a carina but a weak transverse impression is usually present above the foramen. In dorsal view the posterior corners of AII are rounded to obtusely angulate, not extended into projecting sharp angles or stout triangular teeth that project posterolaterally. Lateral surface of AII, below the dorsolateral margin and above the level of the spiracle, usually with a conspicuous longitudinal ridge or carina that extends the length of the sclerite; rarely the carina reduced so that it is only visible to the level of the spiracle. In dorsal view AII, AIII and AIV all distinctly broader than long. Abdominal tergites AII to AIV with numerous setae that are directed posteriorly and are mostly suberect to subdecumbent. Curved setae distinct on sternites of AIII and AIV. Abdominal tergites AII to AVI sculptured only with sparse punctures. Full adult colour black, appendages blackish brown to black; clypeus usually dull reddish; sides of pronotum and sides of abdominal tergites AIII and AIV sometimes with a dull reddish spot, but this is variably developed within series and may be inconspicuous or absent on any sclerite.

Type Material
Holotype worker, Madagascar: Prov. Antsiranana, Forêt Orangea, 3.6 km 128° SE Remena, 90 m, 12°16’S, 49°22’E, 22-28.ii.2001, BLF3196, CASENT0410462, on low veg., trop. dry forest (B.L. Fisher). Paratypes. 2 workers with same data but CASENT0410463; 1 worker with same data but CASENT0410465 (CASC). (Bolton and Fisher 2012)

References based on Global Ant Biodiversity Informatics

 * Bolton B., and B. L. Fisher. 2012. Taxonomy of the cerapachyine ant genera Simopone Forel, Vicinopone gen. n. and Tanipone gen. n. (Hymenoptera: Formicidae). Zootaxa 3283: 1-101.