Strumigenys deltisquama

Known from a small number of specimens, some of which have been found in dry forest. This is in contrast to the type material, stated as being from a locality "covered with rainforest" (Barro Colorado Island).

Identification
Bolton (2000) - The only member of the Strumigenys deltisquama-group. One of the most easily identified Neotropical species, adequately defined by the group characters. In short, the combination of broad head with short flattened wide scapes, dense squamate-orbicular pilosity with lack of standing hairs on head and promesonotum, densely sculptured gaster and strange mandibular structure render this remarkable species immediately recognisable.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia, Costa Rica, Mexico, Panama.

Nomenclature

 *  deltisquama. Strumigenys deltisquama Brown, 1957c: 99, fig. 1 (w.) PANAMA. See also: Bolton, 2000: 508.

Worker
Holotype worker: TL 2.6, HL 0.63, ML 0.34, WL 0.60 mm.; CI 97, MI 54. Scape, exposed L 0.28 mm.; funiculus L 0.48 mm.; apical segment L 0.23 mm. Paratypes, all from type nest series, showed only very slight variation: TL 2.5-2.7, HL 0.62-0.67, ML 0.34, WL 0.60-0.63 mm.; CI 95-97, MI 51-55.

Form of head, mandibles and a scape shown in fig., with pilosity omitted from all parts except anterior clypeal and scape borders. With all the pilosity in place, the head appears relatively shorter and broader and the mandibles shorter, a common type of illusion in heavily pilose dacetine ants. Each inner mandibular margin bears a straight border of translucent lamella extending to the apical quarter of the exposed length, where it ends abruptly and subrectangularly just basad of the proximal preapical tooth (see fig. 1, a). Apical fork with a single intercalary tooth. Dorsal surface of head gently and evenly convex. Compound eye circular, moderate in size, slightly prospicient and usually just barely visible in direct dorsal view of head, with about fifteen facets, four in greatest diameter (equal to 0.04-0.05 mm.). Lateral surfaces of head just in front of eyes broadly and rather deeply concave, the concavity not interrupting the preocular lamina, which arches above it to reach the-eye behind; the concavities are not extended mesad ventrally to form any “postoral grooves.”

Promesonotum broad, subcircular in dorsal view, without humeral angles, depressed, surface gently convex, feebly impressed at site of obsolete promesonotal suture. Posterior mesonotum much narrowed, metanotal groove feeble, scarcely interrupting uniconvex alitruncal profile. Propodeum short, narrow, with a pair of sturdy acute teeth slightly shorter than the distance between the centers of their bases and subtended by narrow, concave, cariniform infradental lamellae. Petiolar peduncle slender, arched, naked beneath, subequal in length to the node; node distinct, just about as long as it is broad behind; from side view with differentiated subequal anterior and dorsal profiles; spongiform appendages confined to a thick rim around posterior margin of node. Postpetiole transverse-oval, small, but wider than petiolar node, maximum width about 0.17 mm., convex, with narrow spongiform margins and moderate lobes beneath; sides partly naked.

Mandibular apices and under-surfaces, apical gastric segments and median posterior gastric venter more or less smooth, shining; body otherwise completely and densely punctulate and opaque. Base of gaster with feeble superimposed costulation extending about half the length of the first segment. Head, with clypeus and scapes, and promesonotum densely covered with thick, orbicular, opaque, yellowish, squamose or stud-like hairs, pseudoappressed, uniform in size, but those on the promesonotum slightly larger. A few other thick squamose hairs also along the sides of the propodeal dorsum, and one applied to the dorsal surface of each propodeal tooth, a few each on the petiolar node and around lateral and posterior borders of postpetiolar node. The squamose hairs of the anterior scape borders have their blades curved ventrad at the apices, and thus appear deltoid to dorsal view; the specific name is in reference to this. Legs with reclinate spoon-shaped hairs; nodes with a few posteriorly-curved, suberect, narrowly spatulate hairs. Gastric dorsum with about six transverse rows of six posteriorly inclined, erect, flattened-clavate hairs, all conspicuous. Inconspicuous fine pilosity on ventral surfaces of head and gaster. Each mandible with three or four dorsal rows of slender, oblique pointed hairs. No trace of specialized erect hairs on head or alitrunk. Feebly concave sides of alitrunk largely naked; only three or four squamose hairs along ventrolateral prothoracic margin on each side. Color uniform light ferruginous.

Bolton (2000) - TL 2.5-2.7, HL 0.63-0.67, HW 0.63-0.65, CI 95-98, ML 0.33-0.34, MI 50-55, SL 0.28-0.30, SI 44-46, PW 0.32-0.34, AL 0.60-0.63 (6 measured).

Type Material
Holotype selected from a series of workers taken by K. W. Cooper during January, 1941, on Barro Colorado Island, Panama Canal Zone. Holotype and paratypes in Museum of Comparative Zoology, Harvard University; paratypes in U.S. National Museum, Coll. K. W. Cooper, and elsewhere. Paratypes, all from the type nest series.

Bolton (2000) - Holotype and paratype workers, PANAMA: Canal Zone, Barro Colorado Island, 7.i.1941 (K. W. Cooper) [examined].