Strumigenys pulchella

In Ohio colonies were found to nest in dead wood.

Identification
Bolton (2000) - A member of the Strumigenys pulchella-group. There are four species in this group that have recurved or reflexed spatulate to spoon-shaped hairs somewhere on the clypeal margins. These peculiar hairs may occur on all margins, or may be confined to one or two pairs on the anterior margin immediately above the mandibles. Of the four pulchella is unique in having a flagellate apicoscrobal hair. Strumigenys reflexa has strikingly posteriorly curved pilosity on the lateral clypeal margins that does not occur in pulchella and Strumigenys missouriensis. Both missouriensis and reflexa have stiff stout hairs at the pronotal humeri and on the mesonotal dorsum, whereas in pulchella these hairs are long, fine and flagellate. Elongate filiform or flagellate hairs are entirely absent in Strumigenys memorialis and are even missing from the pronotal humeri and dorsal (outer) surfaces of the posterior tibia and basitarsus. Instead the cephalic dorsum, pronotal dorsum and tibiae have numerous short erect simple hairs that tend to be blunt apically; this pilosity is not repeated elsewhere in the complex or the group as a whole.

Distribution based on Regional Taxon Lists
Afrotropical Region: Uganda. Nearctic Region: United States.



Biology
Wesson and Wesson (1939) - South central Ohio. We have found this species on about 15 occasions, each time in dead wood. A typical habitat seems to be a log or stump or dead portion of a tree trunk, well-decayed for 3 or 4 cm. beneath the bark, moist but not wet, warm but not in full sun. Such desirable situations are almost always inhabited by species of Aphenogaster, Lasius alienus or Camponotus pennsylvanicus. Whether S. pulchella is definitely associated with the other species, as is S. pergandei, or whether it is simply a matter of such a situation being a very favorable one for other reasons, we have not determined. Although we have seldom taken pulchella workers in the frequented galleries of other ants, the colonies have seemed to be much more definitely associated with a larger species than chance alone would account for.

Several times when logs and stumps were broken open pulchella workers were seen carrying dead springtails in their mandibles, and when kept in an artificial nest they readily captured and killed these insects. They would, however, accept bits of dead flies after having been starved for a few days. Their hunting methods are similar to those of S. pergandei, but the workers are less active. They walk less around the galleries and amid the woody debris provided them and often crouch for hours at a cranny. When a springtail approaches, the worker merely lowers its head, turns in the direction of the quarry and waits. Only when the springtail touches the fore part of its head and mandibles does the pulchella snap and seize it. Once a dead springtail was gently pushed close to a waiting pulchella worker. The latter crept up to about the length of its head away, then crouched, holding its antennae partially folded. After waiting in this position for a considerable time, it rose, extended its antennae and vibrated them rapidly, then crouched again. This was repeated two more times before the ant, as if impatient after 3/ of an hour, walked up to the springtail and seized it.

Winged phases were taken from nests in mid August.

Nomenclature

 *  pulchella. Strumigenys pulchella Emery, 1895c: 327, pl. 8, fig. 19 (w.) U.S.A. Brown, 1953g: 71 (q.m.). Combination in S. (Cephaloxys): Emery, 1924d: 325; in S. (Trichoscapa): Smith, M.R., 1943f: 307; Creighton, 1950a: 309; in Smithistruma: Smith, M.R. 1951a: 828; Brown, 1953g: 70; in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 126. See also: Bolton, 2000: 122.

Worker
Bolton (2000) - TL 1.9-2.1, HL 0.53-0.61, HW 0.34-0.39, CI 62-66, ML 0.07-0.10, MI 12-17, SL 0.27-0.32, SI 78-82, PW 0.24-0.27, AL 0.53-0.59 (20 measured).

Lateral clypeal margins with a fringe of anteriorly curved spatulate to spoon-shaped hairs. Anterior clypeal margin broadly convex; above the mandible with 2 pairs of hairs that curve away from the midline, the outer pair longer than the pair closest to the midline. (Extremely rarely hairs on anterior cIypeal margin above mandibles point anteriorly, but even so they do not follow the arc of curvature of the laterally situated hairs.) Dorsum of clypeus very shallowly concave, with very small inconspicuous spatulate hairs distributed over the surface. Eye with 3 - 4 ommatidia in longest row. Apicoscrobal hair present, flagellate. Cephalic dorsum behind clypeus with spatulate ground-pilosity and with 1-2 pairs of fine filiform to flagellate hairs behind highest point of vertex. Long fine flagellate hairs also present at pronotal humeri, on dorsa of pronotum and mesonotum (easily abraded), and 1-2 on dorsal (outer) surface of hind basitarsus. On petiole and postpetiole hairs are fine, curved filiform to subflagellate. Hairs on first gastral tergite are shorter and filiform, more or less straight to shallowly curved.

Type Material
Bolton (2000) - Syntype workers, U.S.A. District of Columbia, Washington; and Pennsylvania, Beatty (T. Pergande) [examined].