Crematogaster torosa Mayr

Longino, J. T., 2003, The Crematogaster (Hymenoptera, Formicidae, Myrmicinae) of Costa Rica., Zootaxa 151, pp. 1-150 : 120-122

Crematogaster torosa Mayr 1870

Figure 4

Crematogaster torosa Mayr , 1870a:404. Syntype workers: Colombia, Santa Fe de Bogota (Lindig) [ NMW] (examined). Emery, 1922:136; Santschi, 1925:229: combination in C. (Orthocrema) .

Crematogaster brevispinosa var. tumulifera Forel , 1899:84. Syntype workers: Nicaragua, Chontales (Janson) ; and Costa Rica (Tonduz) [ MHNG] (examined). Forel, 1908a:47: description of queen, male. Wheeler, G.C. and Wheeler, J. 1952:260: description of larva. Emery, 1922:134: combination in C. (Orthocrema) . Forel, 1907a:25; Forel, 1908b:369; Forel, 1909:258; Forel, 1912:215: subspecies of brevispinosa . NEW SYNONYMY

Crematogaster arizonensis Wheeler, W. M. 1908b: 482, pl. 27, fig. 40. Syntype workers: USA, Arizona, Tucson and Phoenix , running on cottonwood trees (Wheeler) . Wheeler, W. M. 1912: 132: description of queen, male. Emery, 1922: 134: combination in C. (Orthocrema) . NEW SYNONYMY

Crematogaster brevispinosa subsp. tumulifera var. scurra Forel , 1914a:615 (unavailable name). Worker: Colombia (Gaige) [ MHNG] (examined).

Range

USA at least to Colombia, southern limit of species range not defined.

Description of worker (Costa Rica)

Differing from crinosa in the following respects: mesonotum shorter, promesonotal suture more often impressed, making promesonotal profile flatter; anteroventral petiolar tooth shorter, more often forming nearly right angle rather than long acute tooth; setae on fourth abdominal tergite less abundant, especially medially, such that erect setae more dense anterolaterally.

Measurements

HL 0.682, 0.578, 1.045; HW 0.763, 0.629, 1.179; HC 0.760, 0.598, 1.123; SL 0.488, 0.443, 0.706; EL 0.170, 0.130, 0.259; A11L 0.241; A11W 0.140; A10L 0.118; A10W 0.118; A09L 0.060; A09W 0.085; A08L 0.041; A08W 0.071; WL 0.789, 0.664, 1.269; SPL 0.080, 0.057, 0.142; PTH 0.165, 0.129, 0.280; PTL 0.232, 0.175, 0.380; PTW 0.246, 0.180, 0.373; PPL 0.171, 0.150, 0.265; PPW 0.224, 0.189, 0.371; CI 112, 109, 113; OI 25, 22, 25; SI 72, 77, 68; PTHI 71, 74, 74; PTWI 106, 103, 98; PPI 131, 126, 140; SPI 10, 9, 11; ACI 0.98.

Queen

A normal queen (dorsal face of propodeum drops steeply from postscutellum and much of propodeum appears ventral to scutellum and postscutellum, Fig. 1) with general shape, sculpture, and pilosity characters of the worker; size characters as in Figures 4 and 5.

Biology

Crematogaster torosa has a biology very similar to crinosa and rochai . It occurs primarily in open, seasonally dry areas, highly disturbed areas, and pasture edges, although it can also be found in the canopy of mature wet forest. In Costa Rica it is a common species in urban areas such as the various city parks in the capital, San José.

Nests are large, polydomous, distributed in a wide variety of plant cavities. Dead branches and knots in living trees are most often used. In Guanacaste Province in Costa Rica they often occupy ant acacias, and may invade acacias already occupied by Pseudomyrmex . They often construct small carton baffles that restrict nest entrances and small carton pavilions that shelter Homoptera on surrounding vegetation. In some instances they may inhabit cavities in live stems. I found a large nest in the live stems of a Protium branch (Burseraceae) in Corcovado National Park, and I have found nests in live stems of myrmecophytic Acacia and Triplaris . Nest chambers are sometimes filled with alate queens and males. Based on a sample size of two, colony founding is monogynous. In one case I dissected a small colony in south Texas and found a single physogastric queen in the center. In another case I found a lone foundress queen in a dead branch of a Triplaris tree in Costa Rica.

Foraging is primarily diurnal but occasional nocturnal foragers are seen. Workers are generalized scavengers and they frequently visit extrafloral nectaries. Often columns of workers move between nests.

Comments

This is a member of the crinosa complex and may not always be distinguishable from crinosa and rochai . See under crinosa for further discussion. I examined the type of torosa and compared it directly to Costa Rican material (Corcovado National Park, Sirena, JTL30May82/0830). Museum notes on one of the syntypes were as follows: HL 0.88, HW 0.97, SL 0.61; mandible striate; clypeus feebly striate; fine striae on genae, between antennae and eyes, rest shiny; pronotum with transverse fingerprint-like swirl anteriorly, grading to fine longitudinal striae posteriorly, fading to shiny mesonotum (variable within series), grading to fine striae again near propodeal suture; dorsal face of propodeum short, irregularly striate/punctate; anteroventral petiole sharply angulate, but not produced into a projecting tooth; one flexuous short seta on frons; anterior row of four erect setae on pronotum, two on mesonotum, one each on propodeal spines, two each on petiole, postpetiole, about 11 on fourth abdominal tergite, not including row of 13 on posterior margin; setae on fourth abdominal tergite clustered laterally, leaving median bare; setae on pronotum thinner and longer, rest shorter, flattened; color light orange brown on head, pronotum, grading to dark brown on gaster.

I examined the syntypes of Forel's tumulifera and the additional Costa Rican material on which he based his description of the queen and male. They matched Mayr's torosa in every respect.

Specimens of torosa from the northern end of the range, in southeast Texas and in Arizona, are somewhat smaller and less polymorphic than Costa Rican material, but this seems to gradually change as one moves northward in Mexico. Specimens from Baja California are bicolored, with reddish head and mesosoma, and black gaster. However, the abundant material from Arizona and Costa Rica shows continuous variation in the degree of infuscation of the head and mesosoma, and some material may be clearly bicolored like the Baja material. Specimens from Baja nearly always have a long, acute anteroventral petiolar tooth. Specimens from the state of Arizona in the USA and Sonora and Sinaloa states in Mexico (former arizonensis ) usually have a short but sharply acute tooth as an average condition, but the tooth form varies from long and spine-like to short and right angled. Specimens from southeastern Texas and Costa Rica show a great deal of variability, but usually have a right-angle tooth and less often a short, sharply acute tooth. They never have a long spine-like tooth. For the time being I interpret all this material as torosa , differing from crinosa and rochai by the somewhat flatter promesonotum and the usually shorter petiolar tooth, and with a gastral setal pattern intermediate between crinosa , which has a uniform covering of flattened setae, and rochai , which has no erect setae.