Strumigenys abdita

Identification
Bolton (2000) - The main pilosity of this species appears to be easily lost by abrasion. Very few of the specimens examined exhibited the full complement of long hairs, but the dense and very striking pilosity of the dorsal clypeus is always distinct and obvious.

Four species in this group (abdita, Strumigenys creightoni, Strumigenys deyrupi, Strumigenys metazytes) do not have hairs on the anterior or lateral clypeal margins that are recurved or reflexed. Of these creightoni lacks erect hairs on the vertex close to the occipital margin, lacks an apicoscrobal hair, lacks a fine projecting hair at the pronotal humerus, and lacks standing pilosity on the mesonotum. In the other three species filiform or flagellate hairs are present at all these locations.

P. deyrupi separates from both abdita and metazytes as its main pilosity is entirely of long fine flagellate hairs. These occur as a pair on the vertex close to the occipital margin, a pair on the pronotal dorsum (as well as at the humeri), another pair on the mesonotum, and in numbers on the waist segments and especially the first gastral tergite. In both abdita and metazytes the hairs in many or all of these positions are stouter, simple and stiffly filiform, and at most evenly shallowly curved.

Of the last two species abdita is generally larger and its mandibles are usually longer (HL 0.53-0.60, HW 0.40-0.43, MI 17-22) than in metazytes (HL 0.51-0.52, HW 0.36-0.38, MI 16-17). Also, in abdita the anterior clypeal margin is very wide and has abruptly rounded anterolateral angles. The clypeal dorsum has broadly spatulate to spoon-shaped ground-pilosity that is very dense and conspicuous, and is very similar in shape and size to the hairs that fringe the lateral margins. Standing pilosity on the first gastral tergite is usually restricted to an apical and a basal transverse row, though some samples are known which have intermediate hairs present. By comparison metazytes has a short but very shallowly convex anterior clypeal margin that curves evenly into the lateral margins through widely rounded anterolateral angles. Its clypeal dorsum has minute inconspicuous spatulate ground-pilosity that is very much smaller than the large hairs that fringe the lateral margins. Pilosity on its first gastral tergite is more or less evenly distributed over the sclerite.

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



Nomenclature

 *  abdita. Strumigenys (Cephaloxys) abdita Wesson, L.G. & Wesson, R.G., 1939: 106, pl. 3, fig. 6 (w.) U.S.A. Brown, 1953g: 89 (q.); Brown, 1964a: 189 (m.). Combination in S. (Trichoscapa): Smith, M.R., 1947f: 587; Creighton, 1950a: 304; in Smithistruma: Smith, M.R., 1951a: 827; Brown, 1953g: 89; in Pyramica: Bolton, 1999: 1672; in Strumigenys: Baroni Urbani & De Andrade, 2007: 110. See also: Bolton, 2000: 118.

Worker
Bolton (2000) - TL 2.1-2.3, HL 0.53-0.60, HW 0.40-0.43, CI 69-75, ML 0.10-0.11, MI 17-22, SL 0.30-0.34, SI 73-80, PW 0.26-0.28, AL 0.58-0.64 (10 measured).

Eye with 4-7 ommatidia in total. Ground-pilosity of clypeus dense and curved, of large broadly spatulate to spoon-shaped hairs that are very conspicuous over the entire surface; those located mid-dorsally are just as obvious as those that fringe the lateral margins. Ground-pilosity spatulate and dense on cephalic dorsum behind clypeus. Behind highest point of vertex cephalic dorsum with 1 (sometimes 2) pairs of erect fine hairs. Apicoscrobal hair usually present and filiform (but 2 samples known where this hair appears naturally absent). Pronotal humeral hair long and fine, filiform to subflagellate. Mesonotum with a single pair of erect fine hairs. Dorsal alitrunk also with 2-4 pairs of shorter spatulate hairs that are suberect to erect. Hairs on first gastral tergite usually restricted to an apical transverse row and another row basally; the sclerite between these rows frequently hairless. Middle and hind basitarsi with 1-2 fine flagellate hairs projecting from their dorsal (outer) surfaces. Basigastral costulae extending about one-quarter the length of the tergite.

Type Material
Bolton (2000) - Syntype workers, U.S .A.: Ohio, Jackson (Wesson & Wesson) [examined].