Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Image catalog (click here).
Range
Throughout Neotropics, from southern Mexico to northern Argentina, Antilles.
Identification
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, petiole and postpetiole with pronounced ventral teeth, and appressed tibial pilosity. In Costa Rica the species cannot be confused with any others.
Description of worker
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.
Measurements:
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.
Description of Queen
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.
Natural History
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 SouliŽ's (1960) observation of thelytokous parthenogenesis in C. 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.
Comments
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.
Synonyms
C. curvispinosa Mayr 1870. Mexico to Argentina, Antilles.
= antillana Forel 1893. Antilles.
= sculpturata Pergande 1896.
= kemali Santschi 1923. Brazil (Santa Catarina).
= fuliginea Santschi 1925. Brazil (Minas Gerais).
= accola Wheeler 1934. Mexico.
= phytoeca Wheeler 1934. Mexico.
= panamana Wheeler 1942. Panama.
= obscura Santschi 1929. Argentina.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
Date of this version: 4 March 2003.
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