Strumigenys carolinensis

Holotype and one paratype worker taken in a mature forest of live oak (Quercus virginiana) and loblolly pine (Pinus taeda) along U. S. Route 17 about 1 mile east of Ravenel, Charleston County, South Carolina, on June 9, 1957 (E. O. Wilson and W. L. Brown, Jr. leg.). The workers were taken separately in different parts of the woods, deep in the thick needle litter at the base of large pines. Additional paratypes (2 specimens measured) are in a small series of workers from near Marshville, Union County, North Carolina, in an open, rather dry stand of post oak (Q. stellata) and black jack oak (Q. marilandica), August 9, 1961 (W. G. Carter leg.). The ants came from oak leaf mold in a depression. (Brown 1964)

Identification
Bolton (2000) - A member of the Strumigenys rostrata-group. Of the seven species in the group Strumigenys chiricahua and Strumigenys hyalina are immediately separated as they are the only ones to have a mandibular diastema that is decidedly longer than the basal tooth. Strumigenys californica is isolated by the presence of distinctly sculptured zones at the apices of the first gastral tergite and sternite, these zones remaining smooth and polished in all other species. In the relatively large rostrata (HL 0.61-0.72, HW 0.42-0.47) the dentition is coarse, with teeth 6 and 7 enlarged (see above), and its specialised projecting pilosity is characteristic: stout simple hairs are present in apicoscrobal position, at pronotal humerus and on mesonotum (one pair). The remaining three species, Strumigenys arizonica, Strumigenys bunki, Strumigenys carolinensis, average smaller (HL 0.54-0.64, HW 0.37-0.41) and have much smaller finer dentition (in particular teeth 6 and 7 are insignificant), nor do they have pilosity like rostrata at all the points mentioned; in particular all three lack an apicoscrobal hair. S. carolinensis has a pair of long flagellate hairs on the mesonotum, not developed in arizonica and bunki where mesonotal hairs are simple or absent. These last two species separate on relative development of spongiform tissue (see key) and on the complete lack of mesonotal standing hairs but presence of long fine gastral pilosity in bunki. Compared to this arizonica has a single pair of short simple erect hairs on the mesonotum and the first gastral tergite is sparsely clothed with very short stubbly simple hairs.

Flagellate hairs that project from the dorsal (outer) surface of the hind basitarsus are absent in rostrata and arizonica, always present in carolinensis. In bunki some specimens show such hairs, others do not. Because most bunki I have seen have been badly treated and poorly mounted I suspect that these fine and delicate hairs have been mostly stripped away and that they will always be present in fresh material.

Brown (1964) - This new species has the broad head and the large mandibles of Strumigenys abdita, but the pilosity is less abundant and the hairs broader. It may be regarded as intermediate between Strumigenys bunki and S. abdita.

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

Nomenclature

 *  carolinensis. Smithistruma carolinensis Brown, 1964a: 185, pl. 16, fig. 2 (w.) U.S.A. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 117. See also: Bolton, 2000: 127.

Worker
Holotype TL 2.3, HL 0.55, HW 0.41 (CI 75), ML 0.13 (MI 24), WL 0.58 mm.

Head. Points worthy of note are the broad, rounded clypeus (width ca. 1.5 x length), the anteriorly slightly diverging preocular laminae, and the subangulate scapes. Mandibular dentition approximately as shown in the figure; dentition determined from a paratype with the mandibles opened; note the weak diastema and the large, acute, narrowly triangular basal lamella; 5 teeth in principal apical series; between these and apex, the remaining teeth are minute and denticuliform. In the paratype from which the figure was made, the basalmost tooth of the principal series has an indistinct spur on its basal slope; this spur is present on the left side only, and may be a variable trait as in other North American species of this genus.

S. carolinensis is at first sight very like Strumigenys bunki, but differs from bunki in having longer, heavier mandibles and a broader head and clypeus. The alitrunk also differs in sculpture and pilosity. In S. carolinensis, the median longitudinal carinula is distinct (in the proper view and light) from the rear edge of the mesonotum to the anterior pronotal margin, and the dorsolateral propodeal carinulae are correspondingly more distinct (in S. bunki, the median carinula is obsolete on the pronotum and weak on the mesonotum). The reticulate ground sculpture of the pronotal dorsum is largely effaced and replaced by an indistinct, shallow, loose, longitudinal substriation, contrasting with the distinct fine reticulo-punctation of the mesonotum and weakly shining (in S. bunki, the entire dorsum of the alitrunk is evenly reticulopunctate and opaque). Sides of alitrunk smooth and shining. Alitruncal pilosity similar in the two species, except that the types of carolinensis have the paired humeral hairs long and flagelliform, and there is a second pair of long flagelliform hairs straddling the mesonotum; there are no long mesonotal hairs developed in any of the known samples of bunki. In other characters studied, the carolinensis types are within the range of variability of S. bunki.

Paratype range: TL 2.1-2.4, HL 0.55-0.56, HW 0.39-0.41 (CI 71-73), ML 0.12-0.14 (MI 22-25), WL 0.54-0.58 mm.

Bolton (2000) - TL 2.1-2.4, HL 0.55-0.56, HW 0.39-0.41, CI 71-75, ML 0.12-0.14, MI 22-25, SL 0.30-0.31, SI 72-74, PW 0.25-0.26, AL 0.54-0.58 (3 measured).

Anterior clypeal margin broad, approximately transverse to shallowly convex and with broadly rounded anterolateral angles. Ground-pilosity of clypeus and head behind clypeus of conspicuous spoon-shaped hairs. Apicoscrobal hair absent; cephalic dorsum without slender erect hairs near occipital margin that are differentiated from the ground-pilosity. Scape suddenly expanded at subbasal bend, the leading edge at this point obtusely angulate. Pronotal humeral hair long, fine and flagellate. Mesonotum with a pair of long flagellate hairs. Hind basitarsus with 1-2 long flagellate hairs on the dorsal (outer) surface. Dorsum of pronotum indistinctly shallowly striolate, mesonotum reticulate-punctate, the two contrasting. See notes under Strumigenys rostrata.

Type Material
Holotype and paratypes deposited in the Museum of Comparative Zoology at Harvard University; paratypes will be placed in the U.S. National Museum, the collection of Dr. W. G. Carter at Oklahoma State University, and the Academy of Natural Sciences in Philadelphia.

Bolton (2000) - Holotype worker and paratype worker, U.S.A.: South Carolina, Charleston County, U.S. Route 17 about 1 mile east of Ravenel, 9.vi.1957, in Quercus virginiana and Pinus taeda forest (W. L. Brown & E. O. Wilson); paratype workers, U.S.A.: North Carolina, Union County, Marshville, 9.viii.1961 (W. G. Carter) [examined].