Strumigenys kyidriformis

The only known specimen, the holotype worker, was found with workers of Typhlomyrmex pusillus in a mesophytic subtropical forest at about 1100 m.

Identification
Brown (1964) - This species is named for its convergent resemblance, especially in the rounded, unarmed alitrunk and its head shape and reduced pilosity, to the workers of the Old World genus Kyidris (=Strumigenys). These same features will serve to distinguish it from all other known Smithistruma species. The mandibular dentition is of the Smithistruma pattern, even though the basal lamella is relatively lower than those of most other species.

Bolton (2000) - The only member of the Strumigenys kyidriformis-group.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina.

Nomenclature

 *  kyidriformis. Smithistruma kyidriformis Brown, 1964a: 188,pl. 16, figs. 4, 5 (w.) ARGENTINA. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 122. See also: Bolton, 2000: 200.

Worker
Holotype TL 1.8, HL 0.48, HW 0.40 (CI 83), ML 0.12 (MI 25), WL 0.46; antennal scape L 0.24, funiculus L 0.41 mm., of which half or very slightly more is taken up by the apical segment.

A small, compact species with a rather broad, subtriangular head and a short, dorsally rounded alitrunk with reduced propodeal lamellae.

Mandibles porrect, gently down-curved apicad, with a broad but low and rounded basal lamella and beyond this, with no intervening diastema, a set of short acute teeth and denticles in the pattern usual for the genus. Head convex dorsally, but with a well-marked median impression or sulcus on the vertex. Posterior occipital excision broad and shallow. Clypeus convex in both directions, sloping steeply to its anterior margin, which is almost down to the level of the mandibles. No tumulus detectable on clypeus. Gula convex, no distinct transverse postoral groove. Antennae short and thick; funicular segment III as broad as or slightly broader than long.

Pronotum rounded in front, with a barely perceptible anterior margin, but no humeral angles or tubercles. Promesonotal suture and metanotal groove marked only by faint impressed lines. Propodeal teeth lacking as such, propodeal lamellae reduced, almost cariniform. Petiolar node not very distinct from its peduncle in dorsal view, broader than long. Postpetiolar node proper subreniform, about half again as broad as petiolar node. Basal costulae of gaster coarse, about 12 in number, the middle ones extending about 1/5 the length of the first segment. Legs short and robust, especially the tibiae. Spongiform appendages only moderately well-developed.

Head, alitrunk and both nodes densely reticulopunctate and opaque, except for clypeus and center of postpetiole, which have punctulation feeble and spaced and are predominantly smooth and shining. Mandibles, antennae and legs finely punctulate and subopaque. Almost the entire sides of the alitrunk, sides of petiolar pedicel, and gaster throughout, smooth and shining.

Body clothed in abundant, but not conspicuous, short, curved, reclinate to appressed, rather fine hairs, mostly directed toward the midline on head, alitrunk and gaster; becoming a little longer and obliquely erect on gaster, especially toward apex. Hairs on appendages like those on body, but a little sparser. Clypeal hairs directed anteromesad, those on the free margin about 20, not appressed but reclinate, inclined toward the midline, not forming a conspicuous fringe. No specialized erect hairs on head or alitrunk, and only a few stiffly erect hairs at the gastric apex are moderately long.

Color ferruginous yellow; gaster feebly infuscated in the middle above.

Bolton (2000) - TL 1.7, HL 0.49, HW 0.39, CI 80, ML 0.11, MI 22, SL 0.22, SI 56, PW 0.26, AL 0.46. Clypeus mostly smooth and shining, remainder of head reticulate-punctate everywhere. Dorsal alitrunk, propodeal declivity and dorsum of petiole node densely reticulate-punctate. Disc of postpetiole smooth mid-dorsally, punctate posteriorly and toward the sides. Side of pronotum and bulla of metapleural gland reticulate-punctate; pleurae and most of side of propodeum smooth. Dorsal surfaces of head and alitrunk with abundant fine curved simple hairs that are decumbent to appressed; there are no standing hairs of any form. Hairs on first gastral tergite short, flattened to narrowly spatulate, all oblique or inclined, some appearing minutely bifurcate apically. Vertex with a median longitudinal impression that extends from the posteromedian clypeal margin toward, but not reaching, the highest point of the vertex. Petiole node broader than long in dorsal view. Petiole ventrally with a narrow spongiform strip that is deepest anteriorly. Basigastral costulae widely spaced and sharply defined, extending over about the basal fifth of the sclerite; first tergite otherwise smooth.

Type Material
Holotype a single specimen from Parque Nacional Finca El Rey, Prov. Salta, Argentina, February 23, 1953 (N. Kusnezov leg.), taken with workers of the ponerine ant Typhlomyrmex pusillus; holotype deposited in Museum of Comparative Zoology, Harvard University. The type locality is in mesophytic subtropical forest about 1100 m. above sea level, Lat. 24 o 32' S, in the mountains separating the Valley of Las Cuestas from that of Aguas Blancas, some 50-70 km. east of Ciudad Salta.

Bolton (2000) - Holotype worker, ARGENTINA: Provo Salta, Parque Nacional Finea El Rey, 2.i.1953, no. 8395 (N. Kusnezov) [examined].

Etymology
This species is named for its convergent resemblance, especially in the rounded, unarmed alitrunk and its head shape and reduced pilosity, to the workers of the Old World genus Kyidris (=Strumigenys).