Ants of Ruiz Cortines

Ants of Ruiz Cortines, Veracruz, Mexico

Report by John T. Longino, Michael G. Branstetter, The University of Utah; Jorge Valenzuela, Instituto de Ecología, Xalapa, Mexico. Student participants: Mario Augillar Mendez (Guanajuato), Brianna Bartholomew (Univ. Utah), Rhea Cone (Univ. Utah), Erika Alejandra Conti González (Guanajuato), Miguel Angel García-Martínez (INECOL), Kyle Gray (UC Davis), Dennis Infante (INECOL), Anamin Saraí Lizama Ramírez (Guanajuato), Jaqueline Ochoa Vega (Guanajuato), Madai Rosas Mejía (Guanajuato), Gabriel Somarriba (Univ. Florida).

This is a list of the ants of the cloud forest habitat near Adolfo Ruiz Cortines, in the Los Tuxtlas Biosphere Reserve, Veracruz, Mexico, based on Project ADMAC sampling. Phil Ward provided the list of Pseudomyrmex.

Project ADMAC carried out ant sampling at Ruiz Cortines from 2-7 June 2016. We were accompanied by Bob Anderson and Manuel Barrios, who carried out additional maxiWinkler sampling. Sampling included two miniWinkler transects of 50 samples each (5 m spacing; red dots), maxiWinkler samples (yellow dots), baiting transects (20 baits each, blue dots), beating samples (2hrs, green dots), and Malaise traps (white dots). Most sampling was near our housing at the edge of the Ruiz Cortines community, but MaxiWinkler sampling was more dispersed. Anderson and Barrios sampled along the road to Ruiz Cortines, and we all made two trips to the slopes of Volcán San Martin to sample along an elevational gradient from 1000m to the peak of the volcano around 1600m.

Specimen records have been uploaded to the AntWeb database and are periodically updated. Names in the species list are linked to individual specimen records on AntWeb, from which a link can be followed to the general species page. These specimens function as site-specific vouchers, whose identities may change. The species names in the list are static text on this page. Following the specimen link to AntWeb will allow one to see if the name has changed.

There are at least 110 species. As is typical, the cloud forest fauna is strongly differentiated from the nearby lowland fauna.

Notable discoveries include:

Carebara is a genus found throughout the world in the tropics. It is most diverse in the Old World tropics, but there is a moderate diversity in the New World tropics. Some of the tiniest of all ants in Neotropical leaf litter are Carebara. One of the species is C. intermedia, which previously was known only from northern Central America. One Winkler sample from Volcán San Martin had specimens of C. intermedia, extending the known range to above the Isthmus of Tehuantepec. But an even more interesting finding was that there was another Carebara species that was very similar to C. intermedia, and it was one of the most common ants in the Ruiz Cortines leaf litter. Although similar to C. intermedia, it is definitely a different species, reinforced by the fact that true C. intermedia occurs there as well. This is a species new to science.

An interesting feature of the cloud forest was that this new species of Carebara was very abundant, and seemed to take the place of small Solenopsis (thief ants) in samples. In lowland habitats, and in many cloud forests as well, Winkler samples are typically filled with large numbers of tiny thief ants. At Ruiz Cortines, the tiny yellow ants that were common in samples were Carebara. Solenopsis were relatively rare.

Cyphomyrmex andersoni is a very rare species of fungus-growing ant that is found at very low densities in Winkler samples. It was previously known from Costa Rica to Guatemala. A few specimens were collected at Ruiz Cortines, extending the known range. The specimens differ from all the more southern collections by being darker and with more pronounced tubercles.

Eurhopalothrix zipacna is a visually dramatic ant, named after a Mayan demon. The species was previously known only from Honduras and Guatemala. It was moderately abundant at Ruiz Cortines, extending the known range.

It was great to get another specimen of Fulakora degenerata. This is a minute amblyoponine known from very few specimens. Although the type locality is southern Brazil, a disjunct population (or set of populations) occurs in MesoAmerica. Four specimens were previously known, from Quintana Roo to Honduras. A specimen was in a Winkler sample from the slopes of Volcán San Martin.

Hypoponera inexorata is on the list because of a single specimen from under a rock, in the drier roadside Liquidambar forest that you drive through just before getting to the Ruiz Cortines cloud forest. It was similar to U.S. H. inexorata, but larger and with a larger eye.

The Pheidole fauna of the cloud forest was dominated by P. nebulosa, P. mooreorum, and P. xyston. Moderately abundant were P. wardi and a version of P. harrisonfordi. Pheidole wardi was previously known from Honduras to Chiapas, Mexico. The Ruiz Cortines version is an allopatric variant, morphologically distinct from the southern populations. Pheidole harrisonfordi is a complex of species in litter throughout MesoAmerica. Often cloud forest versions are larger than lowland versions, and that was the case at Ruiz Cortines. Pheidole albipes is on the list because of a single minor worker in a Winkler sample from the slopes of V. San Martin. It was from one of the lower elevation samples, around 1000m. This is a species that is very abundant in the nearby lowlands, and clearly not a cloud forest species. Some other lowland species occurred at low densities.

Pheidole ursus is a dramatic, very large species, with long propodeal spines and a very elongate petiole. It occurs from Costa Rica to northern MesoAmerica, mostly in cloud forest. It shows strong color and sculpture variation throughout its range, and could be multiple species. We collected specimens from the cloud forest, right up to the peak of the volcano, that were orange and relatively smooth. A nest series from Los Tuxtlas Biological Station, in contrast, had workers that were dark brown and more coarsely sculptured.

Procryptocerus mayri is a large, handsome species in this genus. It is a cloud forest specialist and was previously known only as far north as Chiapas, Mexico.

Phil Ward, in his focused Pseudomyrmex collecting at the site, was excited to find two new species of Pseudomyrmex, P. PSW171 and P. PSW172, in the elongatulus and pallidus groups respectively. He comments that at this stage both of them appear to be endemic to the Volcán San Martín region, yet sympatric with their putative close relatives.

Many of the Strumigenys species are range extensions, where the previous known northern limit was Chiapas. Veracruz is a new northern limit for S. azteca, S. biolleyi, S. emeryi, S. probatrix, and S. rogata.

Strumigenys brevicornis is an extremely common ant throughout Central America. It often occurs in two color forms that segregate by elevation, with a lighter red brown version in the lowlands and a darker version in cloud forest. Ruiz Cortines specimens were mostly the dark version, but the red brown version was also moderately abundant, the two often occurring together in the same sample.

Wasmannia auropunctata is famous as the "little fire ant." It was superabundant at Los Tuxtlas Biological Station, even in mature forest, often with hundreds of workers in Winkler samples. It was notably absent from the cloud forest. The single record of W. auropunctata at Ruiz Cortines was a male in a Malaise sample, from a trap set up at the clearing edge near our housing.

Ant List

Acromyrmex echinatior

Adelomyrmex betoi

Adelomyrmex silvestrii

Aphaenogaster JTL-001

Apterostigma pilosum_complex (1 or 2 species)

Atta cephalotes

Azteca coeruleipennis

Azteca forelii

Azteca xanthochroa

Belonopelta deletrix

Bothriomyrmex sp. nr. paradoxus