Strumigenys arahana

Identification
Bolton (1983) - Among the members of the weberi-group six species combine the characters of having the postpetiolar disc without dense costulate sculpture and having the metanotal groove unimpressed. Of these only arahana has the spongiform tissue behind the petiole node very densely and massively developed. In dorsal view the spongiform material is thicker than the length of the node in arahana, whereas in the five other species (Strumigenys fenkara, Strumigenys malaplax, Strumigenys placora, Strumigenys synkara, Strumigenys tolomyla) it is decidedly narrower than the length of the node, in some being merely a lamella.

Distribution based on Regional Taxon Lists
Afrotropical Region: Cameroun.

Nomenclature

 *  arahana. Smithistruma arahana Bolton, 1983: 300 (w.) CAMEROUN. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 115. See also: Bolton, 2000: 336.

Worker
Holotype. TL 2.5, HL 0.65, HW 0.40, CI 61, ML 0.05, MI 8, SL 0.28, SI 70, PW 0.30, AL 0.64.

Anterior clypeal margin transverse, the anterolateral angles rounded and the lateral margins feebly divergent posteriorly. Outline of preocular laminae shallowly convex in full-face view, broadest at about their midlength and slightly convergent both anteriorly and posteriorly. Lateral margins of clypeus with simple projecting hairs, the shorter of which are curved anteriorly and the longer of which curve upwards or forwards and upwards. Clypeal and cephalic dorsa equipped with simple fine ground-pilosity, the hairs of the ground-pilosity short and arched forward so that their apices are in contact or nearly in contact with the surface. Projecting above the ground-pilosity are longer stouter simple hairs which are erect or nearly so. On the clypeal dorsum most of these hairs curve forward then upward but the posteriormost clypeal row are shallowly sinuate and are also the longest. Behind the clypeus similar erect curved to sinuate hairs are present, none of which are longer than the posterior clypeal row. Close to the occipital margin are a few hairs which are angled and have their apical portions narrowly flagellate. In full-face view the sides of the head with numerous projecting simple hairs. Antennal scapes slightly bent in the basal third, broadest at about the midlength, the leading edge with anteriorly projecting simple hairs most of which are upcurved in their distal halves. Dorsum of head coarsely and very densely reticulate-rugulose everywhere, the clypeus less strongly sculptured. Promesonotum not marginate, the pronotal dorsum without a median longitudinal carina. Metanotal groove not impressed. Propodeal teeth broad and triangular, short, the infradental lamellae vestigial and represented only by a narrow rim; outline of the propodeal declivity in profile distinctly concave. Sides of pronotum and propodeum coarsely rugose, the pleurae smooth. Mesopleuron with a dense vertical band of fine punctulae close to its junction with the metapleuron but otherwise the pleurae only with very widely scattered fine punctulae. Promesonotal dorsum coarsely and densely rugose, the propodeal dorsum smooth except for a few feeble anteriorly situated punctures. Dorsal alitrunk with numerous fine simple hairs. Spongiform appendages of pedicel segments massively developed in profile. Outline of petiolar ventral process concave at about its midlength, the ventral postpetiolar lobe very large indeed. In dorsal view the petiole node rugose and distinctly broader than long, with a very thick posterior ruff of dense spongiform material, the thickness of which is greater than the length of the exposed dorsum of the node. Laterally the spongiform tissue laps around the sides of the node almost to the anterolateral angles. Disc of postpetiole in dorsal view completely surrounded by dense thick spongiform material, the disc uneven and with scattered punctures, not glassy smooth as is usual in the weberi-complex but lacking the strong costulae characteristic of the minkara-complex. Anterior margin of postpetiolar disc bordered by a dense spongiform strip, the sides with dense spongiform tissue which is narrowest anteriorly and extremely broad posterolaterally. Posterior spongiform strip broad and with a narrow median cleft. Base of first gastral tergite with a broad very finely and densely spongiform transverse strip, the tergite posterior to this with short basigastral costulae. Dorsal surfaces of petiole, postpetiole and gaster with numerous fine simple hairs. Colour dull brownish yellow to light brown.

Paratype. TL 2.6, HL 0.70, HW 0.43, CI 61, ML 0.06, MI 9, SL 0.30, SI 70, PW 0.32, AL 0.70.

As holotype but disc of postpetiole less noticeably punctate.

Type Material
Holotype worker, Cameroun: nr Yaounde, sample D2 (G. Terron). Paratype. 1 worker, Cameroun: nr Yaounde, sample 2419 (G. Terron).