Strumigenys alessandrae

Specimens have been collected from leaf litter in secondary forest.

Identification
Rigato (2006) - An easily recognisable species for its unarmed left mandibular shaft and the presence of an intercalary tooth on the left mandibular fork. It is quite different from any other Afrotropical Strumigenys known to date and may constitute a species-group of its own.

Strumigenys alessandrae-group contains Strumigenys alessandrae only and may be defined from the following combination of characters:

1) Apical fork of the left mandible with an intercalary tooth, right mandible with just a vestigial intercalary denticle. Preapical teeth absent from the left mandible; the right mandible has one preapical tooth close to the insertion of the apicodorsal one.

2) Scape slender and simple. SI 87-88.

3) Upper scrobe margin weakly developed.

4) Postoral and preocular notches deeply incised; the latter runs ventrally, bends backward at a right angle and fades away along the median suture.

5) Spongiform appendages relatively well developed on postpetiole; but reduced to a collar on the posterior face of the petiolar node. First gastral sternite devoid of any spongiform structure.

6) Apicoscrobal hair absent. Cephalic dorsum with appressed, narrowly spoonshaped hairs only. Pronotal humeral hair present, clavate. Mesonotum with a single pair of clavate hairs. Petiole, postpetiole and gaster with standing clavate hairs.

7) Head, alitrunk, petiole and postpetiole mostly finely reticulate-punctate; mesopleuron smooth in the middle. Gaster smooth except for basal costulae.

Distribution based on Regional Taxon Lists
Afrotropical Region: Ethiopia.

Nomenclature

 *  alessandrae. Strumigenys alessandrae Rigato, 2006: 104, figs. 1  3 (w.) ETHIOPIA.

Worker
Holotype. TL 3.6, HL 0.96, HW 0.69, CI 72, ML 0.51, MI 53, SL 0.61, SI 88, PW 0.40, AL 0.94

A relatively large and slender species.

Head dorsally with a longitudinal shallow median groove. Mandibles slightly bowed outward. Left mandible without any preapical tooth; right mandible with one preapical tooth placed just above the apicodorsal one, so that both mandibular shafts look unarmed in full-face view. Apical fork of the right mandible with a very minute vestigial intercalary denticle close to the base of the apicoventral tooth; left mandible with a well developed intercalary tooth. Apicodorsal tooth of both mandibles larger than apicoventral one. In full face view anterior clypeal margin almost straight, occiput deeply notched in the middle. Postoral and preocular notches deeply incised, the former narrow and deep in profile and with a narrow rim. The preocular groove becomes wide and shallow ventrally; then it bends backward at a right angle and fades away while running along the median suture. Scape slender and simple. Antennal scrobe relatively well developed, its dorsal margin slightly sinuate and weakly edged. Alitrunk humped in profile: pronotum and anterior mesonotum convex and overhanging the nearly straight posterior mesonotum and propodeum; mesonotum margined laterally. Propodeal teeth small; their ventral edges run downward as a narrow lamella along each side of the propodeal declivity.

Petiole with a long peduncle, ventrally a very thin longitudinal crest runs along the entire length of the petiolar sternite. Node simply domed in profile. Petiolar spongiform appendage forming a thin collar around the posterior face of the node. Postpetiole wider than long and about twice as wide as the petiole. Postpetiolar spongiform appendage more developed posteriorly, especially below where it forms two longitudinal crests.

Gaster basally with an anterior tergal spongiform crest fitting the postpetiolar one.

Sculpture. Head, alitrunk, petiole and postpetiole mostly matt and finely reticulate-punctate all over; mesopleuron smooth in the middle; mandibles and postoral groove smooth. First tergite and sternite basally sculptured, longitudinally finely costulate for about 2/5 of tergal and 1/3 of sternal lengths.

Pilosity. Anterior clypeal margin fringed with moderately long, curved, simple to slightly clavate hairs; head dorsum covered with regularly arranged, anteriorly bent and somewhat appressed, narrowly spoon-shaped hairs. Cephalic dorsum devoid of any erect hair. Leading edge of the scape bearing a series of simple hairs curved toward the apex of the segment. Pronotum with a pair of long, standing, slightly clavate humeral hairs; anterior mesonotum with a pair of slightly shorter, clavate ones; dorsum of the alitrunk with sparse, appressed, coarse pubescence especially on the pronotum. Petiole with a pair of clavate hairs on the back of the node; postpetiole with 3 pairs of clavate hairs: one pair short, decumbent, anteromedial ones and two pairs close to the articulation with the gaster, the mid pair longer. Gastral tergites with regularly arranged, scattered, long, somewhat subdecumbent, clavate hairs; sternites and gastral apex with several decumbent to subdecumbent simple hairs. Pubescence quite long and abundant on the appendages only.

Colour testaceous.

Paratypes. TL 3.6, HL 0.96-0.98, HW 0.69, CI 70-72, ML 0.50, MI 51-52, SL 0.60-0.61, SI 87-88, PW 0.39-0.40, AL 0.90-0.92.

Closely matching the description of the holotype, even for the presence of the minute intercalary denticle on the right mandibular fork.

Type Material
Holotype (worker): Ethiopia, Ilubador Region, Buno Bedele: nr. Bedele, (approx. 8°27’ N – 36°21’ E), 2000 m ca., 29/31.VII.2002 A. Sforzi & L. Bartolozzi legit, sifting leaf litter of secondary forest. Paratypes: 2 workers with the same data as the holotype.

Etymology
This species is dedicated to Alessandra Sforzi (MZUF), one of the collector of this new ant.