Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Image catalog (click here).
Range
Nicaragua, Costa Rica, Ecuador.
Identification
The combination of very long, divergent propodeal spines and abundant erect tibial setae uniquely identify this species. Crematogaster nigropilosa has similar large spines, but the pilosity on the tibiae is appressed.
Description of worker
Color dark red brown to black, head and gaster darker than mesosoma, tarsi, and terminal 2-3 segments of antenna yellow or at least much lighter brown.
Mandibles smooth and shiny; in full face view anterior margin of clypeus weakly convex; clypeus convex, shiny; face smooth and shiny; scapes smooth and shiny, slightly clavate, with abundant curved erect setae, setae about as long as width of scape; terminal 2-3 segments of antenna gradually lengthening to form club, becoming increasingly densely pubescent, terminal two segments the largest and most conspicuous; face with abundant erect flexuous setae; in full face view with abundant setae projecting from sides and posterior margin of head, both anterior and posterior to eyes; ventral surface of head with moderately abundant suberect setae.
In lateral view, promesonotum elongate, pronotum forming sigmoidal curve as it rises from anterior collar to weakly convex dorsal surface, continuous with anterior half of mesonotum, posterior half of mesonotum dropping steeply to propodeal suture; promesonotum elevated above propodeum; mesonotum with pair of pronounced lateral carinae, rounded and smooth anteriorly, becoming sharper posteriorly and converging to join small lateral carinulae that bridge propodeal suture; dorsal and posterior faces of propodeum differentiated, meeting at an angle; propodeal spines large, long, narrowly acute and spiniform, projecting upward and strongly diverging; side of pronotum always smooth and shining, pronotal dorsum smooth and shining or with faint longitudinal etching; katepisternum smooth and shining or with variably developed faint microareolate sculpture; side of propodeum smooth and shining or with faint microsculpture; dorsal face of propodeum smooth and shining to finely and faintly longitudinally striate; posterior face of propodeum smooth and shining; pair of long erect flexuous setae on pronotal humeri and anterior mesonotum, shorter erect setae scattered over promesonotum, dorsolateral margins of propodeum, and onto propodeal spines; legs with abundant short erect setae, setae shorter than width of tibiae.
Petiole in side view elongate, smooth and shining or with faint microsculpture, with variably developed small anteroventral tooth; in dorsal view, dorsal face of petiole long triangular, strongly and regularly converging anteriorly, widest posteriorly, smooth and shining, with seta projecting from side near spiracle, and 1-2 setae on posterolateral corners; petiole with slight bulge at petiolar spiracle, visible in both dorsal and along ventral margin in lateral view; ventral margin of postpetiole with denticle; postpetiole in dorsal view globular, with 2 pairs erect setae; fourth abdominal tergite smooth and shining or with faint microareolate sculpture, with abundant long flexuous erect setae.
Measurements:
HL 0.660, 0.655, 0.761; HW 0.646, 0.634, 0.776; HC 0.593, 0.570, 0.700; SL 0.738, 0.717, 0.812; EL 0.149, 0.150, 0.168; A11L 0.282; A11W 0.106; A10L 0.142; A10W 0.079; A09L 0.083; A09W 0.057; A08L 0.061; A08W 0.049; WL 0.830, 0.798, 0.944; SPL 0.278, 0.309, 0.427; PTH 0.147, 0.142, 0.178; PTL 0.290, 0.276, 0.326; PTW 0.161, 0.170, 0.202; PPL 0.175, 0.147, 0.184; PPW 0.171, 0.159, 0.213; CI 98, 97, 102; OI 23, 23, 22; SI 112, 109, 107; PTHI 51, 51, 55; PTWI 56, 62, 62; PPI 98, 108, 116; SPI 33, 39, 45; ACI 0.79.
Description of Queen
A normal queen (dorsal face of propodeum drops steeply from postscutellum and much of propodeum appears ventral to scutellum and postscutellum); head and mesosoma often covered with wax layer; color red brown, usually with lighter yellow scapes, antenna tips, and legs; head pilosity and sculpture characters as in worker; terminal 5 segments of antenna gradually enlarging to form club, the last two largest and most conspicuous; pronotal dorsum short, perpendicular, forming continuous profile with large mesonotum; propodeal spine variable, low and broadly triangular with blunt tip or somewhat produced with well-defined acute tip; abundant medium length setae on dorsal mesonotum and scutellum, anterolateral pronotum, lower katepisternum, and clustered around base of propodeal spine; femora and tibiae with abundant erect setae; petiole subtriangular in side view, anteroventral tooth small, bluntly obtuse to subacute; in dorsal view, dorsal face of petiole strongly convex posteriorly, strongly tapering anteriorly, with distinct tumosities at petiolar spiracle, with small erect seta projecting laterally near spiracle, and long erect seta on each posterolateral corner; postpetiole with no ventral tooth, subtrapezoidal in dorsal view, smooth and shiny, widest anteriorly, with a dorsal pair and posterior pair of long setae; fourth abdominal tergite smooth and shiny with sparse erect setae.
Natural History
Crematogaster longispina occurs in very humid conditions in wet forest. Although it occurs at sea level, it is more common at elevations slightly higher, around 500m. It forms small carton nests, usually no more than 10-15cm across, on low vegetation and tree trunks (figs. 1,2). The carton is very loose and friable, and falls away easily on disturbance. These carton nests often host an array of sprouting epiphytes, and are penetrated by roots from epiphytes growing in the vicinity. Nests are usually packed with workers and brood, one or more physogastric queens (polygyny is common), and scattered coccoid Homoptera on the penetrating roots. Nests are locally abundant, occurring on many adjacent trunks or scattered through low vegetation. The nest dispersion and polygyny suggest polydomy and perhaps unicoloniality. In spite of many observations of nests, I have never observed adult males or alate queens.
Kleinfeldt (1978) studied a colony or colonies of C. longispina at La Selva Biological Station in Costa Rica, investigating its relationship to a common ant garden inhabiting epiphyte, Codonanthe crassifolia (Gesneriaceae).
The site at La Selva where Kleinfeldt carried out her study has been increasingly developed as a laboratory clearing, and the surrounding landscape has seen increasing deforestation. Crematogaster longispina no longer occurs at Kleinfeldt's study site, and in fact appears very rare at La Selva. I have only encountered it near the back edge of the La Selva station property, along a stream margin in a deep forested ravine. This species may require constantly high humidity levels and be particularly sensitive to habitat fragmentation and edge effects, especially at low elevations.
 Figure 1. Typical nest of Crematogaster longispina, with sprouting epiphytes. |
 Figure 2a. A second example of a nest. |
 Figure 2b. Closer view of nest with outer wall removed, showing workers and brood inside. |
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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