Crematogaster curvispinosa

This is an inconspicuous species with small colonies of a few dozen workers. Their nests can be common nesting in disturbed areas, with colonies opportunistically inhabiting small cavities in dead and live plants.

Identification
Longino (2003) - This species has uniquely shaped propodeal spines, with broad divergent bases and an abrupt transition to small posteriorly directed tips. Other characters include abundant short stiff setae on the face, clathrate or lattice-like sculpture on the pronotum, and appressed tibial pilosity. In Costa Rica the species cannot be confused with any others. Crematogaster curvispinosa appears relatively uniform over a broad range, usually with no closely related species. Only in Peru have I found what appear to be two morphospecies with the same general habitus as curvispinosa but differing in details of sculpture and pilosity. The type worker of curvispinosa is headless, but it is clearly the widespread species I have called curvispinosa. The diagnostic characters are clearly visible: clathrate sculpture on pronotum, raised mesonotum, broad-based curving spines, punctate petiole with ventral tooth, and stiff erect setae throughout.

Distribution
Longino (2003) - Throughout Neotropics, from southern Mexico to northern Argentina, Antilles.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Barbados, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Galapagos Islands, Guadeloupe, Guatemala, Guyana, Honduras, Lesser Antilles, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, Uruguay, Venezuela.

Biology
Longino (2003) - Crematogaster curvispinosa is a very common but inconspicuous ant. It is most common in brushy habitats, road edges, young second growth, and other highly disturbed areas. Colonies are small, and there is no evidence of polydomy. They are most often found nesting in narrow gauge dead stems. Nests may occur in dead grass stalks or vine stems that are only 2mm outside diameter. They also occur opportunistically in single chambers of antplants such as Cecropia, Cordia alliodora, Triplaris, and myrmecophytic melostomes.

Colonies are small, a few dozen workers at most. Ergatogynes are common, and the reproductive structure of colonies is variable. Along with workers and brood, I have collected nests that contained (1) no apparent reproductive, (2) one ergatogyne, (3) one physogastric queen, or, in one case, (4) two ergatogynes and one physogastric queen. I have never seen a nest with multiple queens, or multiple ergatogynes in the absence of a queen. In one case I collected a nest with workers, brood, and one ergatogyne and kept it alive in the laboratory for about one year. The colony was not closely monitored or cared for, but sporadic feeding and observations yielded a surprising result. After about two months I found the ergatogyne wandering alone outside the nest tube, and she soon died. What remained in the tube were some adult workers, several large larvae, some queen pupae, and one callow alate queen. There was no worker brood. Several months later there were some adult males in the nest, but my notes are incomplete regarding other contents. Nearly a year from the time of collection the nest contained 14 queens, some with ragged wing stubs but most fully alate, a few workers, and a brood pile. Thus the colony began with an ergatogyne, workers, and brood, went through a bottleneck with only workers and unmated queens (no males), then later reconstituted a colony capable of producing new queens and workers. There were no other nests of curvispinosa in the laboratory, and the laboratory was in the United States, far from the native range of curvispinosa, so contamination from other colonies or access to males from other colonies was not possible. It appears that C. curvispinosa can produce female offspring from only workers and virgin queens. This is similar to Soulié's (1960) observation of thelytokous parthenogenesis in  Crematogaster scutellaris.

Crematogaster curvispinosa can tolerate nesting in close proximity to larger ant species. Twice I have found curvispinosa nesting in the same hollow stem with another ant species, Camponotus in one case and Dolichoderus in another, with the two nests separated by only a narrow sawdust plug. Colonies can occupy single Cecropia internodes that are sandwiched between internodes occupied by Azteca.

Workers appear to forage day and night. Isolated foragers are common on low vegetation, and they are frequent visitors at extrafloral nectaries.

Schmid et al. (2014) found this ant nesting in infructescences (the stem and remains of buds and fruits above the level of the water reservoir in the rosette) of the bromeliad Vriesea friburgensis on Santa Catarina Island, Brazil. De Oliveira et al. (2015), studying ant occupancy of Cecropia trees in southwest Bahia, Brazil, found two colonies of  opportunistically nesting in Cecropia pachystachya trees. Gillette et al. (2015) in a Chaipas, Mexico field study of twig-nesting ants in coffee plants found C. curvispinosa nesting on plants between 500-1200 m in elevation.

Nomenclature

 *  curvispinosa. Crematogaster curvispinosa Mayr, 1862: 768 (w.) BRAZIL. Forel, 1911c: 301 (q.); Forel, 1912f: 216 (m.). Combination in C. (Orthocrema): Emery, 1922e: 134. Senior synonym of fuliginea: Santschi, 1929f: 88; of accola, antillana, kemali, obscura, panamana, phytoeca, sculpturata: Longino, 2003a: 55.
 * antillana. Crematogaster curvispinosa var. antillana Forel, 1893g: 399 (w.) ANTILLES. Forel, 1912f: 216 (q.). Combination in C. (Orthocrema): Emery, 1922e: 134. Junior synonym of curvispinosa: Longino, 2003a: 55.
 * sculpturata. Crematogaster sculpturata Pergande, 1896: 876 (w.) MEXICO. Wheeler, W.M. 1934g: 171 (w. redescribed). Combination in C. (Orthocrema): Emery, 1922e: 136. Junior synonym of curvispinosa: Longino, 2003a: 55.
 * kemali. Crematogaster (Orthocrema) curvispinosa var. kemali Santschi, 1923c: 250 (w.) BRAZIL. Junior synonym of curvispinosa: Longino, 2003a: 55.
 * fuliginea. Crematogaster (Orthocrema) fuliginea Santschi, 1925d: 231 (w.) BRAZIL. Junior synonym of curvispinosa: Santschi, 1929f: 88.
 * obscura. Crematogaster (Orthocrema) curvispinosa var. obscura Santschi, 1929d: 293 (w.) ARGENTINA. [Unresolved junior primary homonym of obscura Smith, F. 1857a: 76.] Junior synonym of curvispinosa: Longino, 2003a: 55.
 * accola. Crematogaster (Orthocrema) sculpturata subsp. accola Wheeler, W.M. 1934g: 175 (w.) MEXICO. Junior synonym of curvispinosa: Longino, 2003a: 55.
 * phytoeca. Crematogaster sculpturata subsp. phytoeca Wheeler, W.M. 1934g: 173 (w.q.m.) MEXICO. Junior synonym of curvispinosa: Longino, 2003a: 55.
 * panamana. Crematogaster (Orthocrema) curvispinosa var. panamana Wheeler, W.M. 1942: 195 (w.q.) PANAMA. Junior synonym of curvispinosa: Longino, 2003a: 55.

Worker
Longino (2003) - HL 0.572, 0.586, 0.632; HW 0.610, 0.580, 0.664; HC 0.565, 0.561, 0.626; SL 0.513, 0.523, 0.576; EL 0.142, 0.152, 0.140; A11L 0.236; A11W 0.105; A10L 0.126; A10W 0.091; A09L 0.050; A09W 0.060; A08L 0.046; A08W 0.056; WL 0.626, 0.602, 0.678; SPL 0.125, 0.154, 0.180; PTH 0.159, 0.150, 0.166; PTL 0.185, 0.194, 0.217; PTW 0.177, 0.161, 0.187; PPL 0.158, 0.154, 0.184; PPW 0.188, 0.164, 0.205; CI 107, 99, 105; OI 25, 26, 22; SI 90, 89, 91; PTHI 86, 77, 76; PTWI 96, 83, 86; PPI 119, 106, 111; SPI 20, 26, 27; ACI 2.66.

Color usually dark red brown to black.

Mandibles smooth and shiny; face largely smooth and shiny, with variable extent of microareolate sculpture around antennal insertions; scapes with 5-10 long, erect, delicate setae and abundant long decumbent setae; antennal club 2-segmented; clypeus with 2-4 longitudinal rugae; face with 20-30 short, stiff, erect setae; ventral surface of head with 0- few erect setae.

In lateral view, dorsal profile of pronotum, mesonotum, and propodeum usually forming continuous curve, mesonotum sometimes somewhat elevated, forming weak promesonotal suture, dorsal and posterior faces of propodeum in same plane, sloping to petiolar insertion; propodeal spines projecting posterodorsally; pronotal dorsum with clathrate sculpture forming a lattice of longitudinal and transverse carinae with smooth and shiny interspaces; mesonotal dorsum with two elevated longitudinal carinae laterally, irregular clathrate rugulae medially; propodeal suture impressed medially but not visible in side view because lateral mesonotal carinae continue onto dorsal face of propodeum; mesonotal carina may have slight tooth at propodeal suture; dorsal face of propodeum with faint aerolate rugulose sculpture, posterior face smooth and shining; in dorsal view propodeal spines highly distinctive, with bases broad, weakly tapering, divergent, then abruptly bent to form short, sharp, posteriorly directed tips; side of pronotum flat, largely smooth and shining, with faint line of punctation dorsally; medial portion of katepisternum with variable extent smooth and shining, perimeter strip and anepisternum punctate to faintly microareolate; side of propodeum with variable extent and strength of punctate sculpture, densest ventrally, becoming smoother dorsally; setae on mesosomal dorsum stiff, relatively short, of variable length, longest approximately 0.16mm long, dorsum of pronotum with anterior row of four setae, anterolateral and posterolateral dorsum of mesonotum (at propodeal suture) each with a seta; propodeal spine with 1-2 setae at angle where spine bends posteriorly; additional short setae variably present on mesosomal dorsum; legs with dilute appressed pubescence and no erect setae.

Petiole in side view trapezoidal; side faintly microareolate/punctate; anteroventral tooth produced, forming a right angle or more often acute; dorsal face subrectangular, somewhat longer than wide or more often almost as wide as long, smooth and shining; posterolateral tubercles each with two stiff setae; postpetiole globular, with no trace of median sulcus or posterior emargination; with small anteroventral tooth; dorsum smooth and shining or faintly microareolate; with 4-6 stiff erect setae; fourth abdominal tergite smooth and shining, with 15-25 stiff erect setae and very dilute short appressed pubescence; although setae of fourth abdominal tergite vary in density, length, and stiffness; one specimen from Santarem is an outlier with about 40 distinctly shorter, stiff erect setae.

Queen
Longino (2003) - A normal queen (dorsal face of propodeum drops steeply from postscutellum and much of propodeum appears ventral to scutellum and postscutellum) with general shape, sculpture, and pilosity characters of the worker; size characters as in Figures.

Type Material
Longino (2003) - Holotype worker: Brazil, Rio de Janeiro (Novara) (examined).