Cerro Musún

Ants of Reserva Natural Cerro Musún, Nicaragua

Report by John T. (Jack) Longino, The University of Utah; Michael G. Branstetter, The University of California, Davis; Laura D. Sáenz, Universidad de San Carlos, Guatemala; and P. S. Ward, The University of California, Davis.

This is a working list of the ants of Ants of Reserva Natural Cerro Musún, Nicaragua, based on Project LLAMA sampling. Specimen records have been uploaded to the AntWeb database and are periodically updated.

This is a static webpage with links to the AntWeb species pages, where you can see distribution maps on Google Earth. If links are dead, that means the database has changed as hypotheses of species boundaries evolve and names change.

There is a minimum of 275 species so far recorded.

Cerro Musún is an isolated peak in the western portion of the Caribbean lowlands. It is a habitat island of mature evergreen forest surrounded by a generally deforested and agricultural landscape. Downloadable maps of vegetation cover and human landuse history are available at the bottom of this page. The ant fauna is complex, a mixture of lowland and montane, southern and northern faunal elements. The forest begins just above 600m elevation and extends to the peak at just above 1400m. Species richness is highest in the lowest tier of forest and drops linearly to near zero at the peak (Fig. 1).

Figure 1. Ant species richness of maxiWinkler samples as a function of elevation. Species richness is for a subset of ant genera that were sorted to species.

There is high species turnover with elevation. Many of the species in the forest at 700m do not occur above 1000m. Other species are common at higher elevations but do not occur below 1000m. Species with minimum elevation > 1000m yet moderately to very abundant above that elevation are Adelomyrmex myops (oddly, since this is a lowland species elsewhere), Eurhopalothrix schmidti and an undescribed species, Pyramica cassicuspis, Py. microthrix, Py. lalassa, Pheidole rectisentis and Ph. guerrerana, Cryptopone gilva, Strumigenys timicala, Pachycondyla aenescens and a Pa. ferruginea-group species, an undescribed Octostruma, an undescribed Stenamma, and Tatuidris tatusia (very abundant in a band from 1100-1300m, absent above and below).

The elevational segregation of species results in different biodiversity conservation threats for different segments of the biota. The lowland fauna is threatened by encroachment from surrounding farms and other forms of development. The upland fauna is threatened by climate change.

The fauna is highly diverse. Many species are shared with the Caribbean forests of Costa Rica and are at or near their northern range limit. Other species are at their southern range limit. Three species are currently known only from Reserva Musún: one undescribed species of Gnamptogenys and two undescribed Pheidole. There were several notable occurrences. Anochetus bispinosus is a South American species known to be extremely rare in Central America. Previously only one Central American collection was known; 3 workers from a fogging sample taken at La Selva Biological Station in Costa Rica. A lone worker was found in a beating sample taken at Musún. Crematogaster arcuata is a largely South American species whose northern range limit was thought to be the Osa Peninsula of Costa Rica. Crematogaster monteverdensis is a species very like C. sumichrasti and previously only known from Monteverde, Costa Rica. Rogeria scandens was only known from two collections, one in Honduras and one in Panama; a worker was collected at a bait in Musún. Strumigenys diaptyxis was known only from two workers from mid-elevation, Costa Rica; a nice series was collected at Musún.