Crematogaster nigropilosa occurs in a wide variety of habitats and elevations, with the exception of extremely dry areas. It is common in low to mid elevation rainforests, and may be found in moist microhabitats in seasonally dry areas. Although most abundant at low to middle elevations, it also can occur at high elevation cloud forest sites where virtually no other ants are found. I collected a worker in a Winkler sample at 2400m elevation on Volcan Barva in Costa Rica, and Peck collected the species at 2600m in Chiriqu’ province, Panama.
Nests are often in soft bits of dead wood or small hollow plant stems. The nests are usually on the forest floor or within a few meters of the forest floor in shaded areas and understory. I have also seen nests in rotten stumps, in chambers in rotting walls of abandoned houses in rainforest, and occasionally in internodes of Cecropia saplings. Nests contain a worker population ranging from a few dozen to about 300. Ergatogynes are very common. Nests exhibit a range of reproductive structures. Some have a standard complement of workers, brood, and one colony queen. Others have the colony queen plus one or more ergatogynes. An example is a colony I collected in its entirety from two adjacent internodes of a Cecropia sapling. The colony contained one dealate queen, 28 alate queens, 11 adult males, 13 ergatogynes, 324 workers, and brood. Nests may be queenless, containing only workers, brood, and one or more ergatogynes. Often these queenless nests appear to be the only nest in the vicinity, with no indication of being part of a polydomous colony. Although most of the nests I have observed have been monogynous or lacking a queen, one nest collection from Venezuela was polygynous. A lab colony kept for about one year was comprised of workers and one ergatogyne. The colony continually produced males as the worker population gradually declined to extinction. Thus a queenless colony fragment is at least able to produce males.
Foragers may be found day or night. They occur on extrafloral nectaries and have been taken at tuna baits on the ground.
Nicaragua to Bolivia, Brazil.
Taxonomic history
Mayr, 1887 PDF: 624 (q.); Morgan & Mackay, 2017 PDF: 283 (m.).Combination in Crematogaster (Orthocrema): Emery, 1922c PDF: 136.Combination in Crematogaster (Orthocrema): Blaimer, 2012c PDF: 55.See also: Longino, 2003a PDF: 94.
