Abstract The influence of Guarea guidonia (L.) Sleumer diaspore abundance on ants’ preference was studied in a secondary tropical forest area in Brazil. We offered seeds in stations with different abundances (one, two, five or 10 diaspores) for interactions with ants. The number of interactions and of ants were influenced by diaspore abundance during the observation period. Stations with 10 diaspores maintained a high number of interactions throughout the experiment. Incidence of seed cleaning differed among the four groups. Moreover, the number of interactions was positively related to the average percent of seeds cleaned. Diaspore abundance proved to be important for promoting more interactions with ants. Considering that the proportion of seeds cleaned increased with the number of interactions, further experiments should observe ant activity for a longer period. Furthermore, diaspore abundance should be considered in future studies of interactions with ants.

ABSTRACT Ants interact with seeds, and frequently remove their appendages. This work aimed to evaluate the effect of ants on the germination of Guarea guidonia (Meliaceae) seeds through removing the fleshy tissue of their integument (sarcotesta). The seeds were subjected to the following treatments: control (no sarcotesta removal), manual removal, and removal by ants. The results show that germination percentage and time varied among treatments, with removal by ants showing the highest percentage within the shortest possible time. The positive effect of sarcotesta removal by ants points to a possible action of anti-fungal substances. As germination is an essential step for recruitment, ant activity may be important to the regeneration of a deforested area. Further studies should consider germination experiments under natural conditions in order to increase the understanding on plant development.

O gênero de formigas cultivadoras de fungos, Mycetagroicus Brandão & Mayhé-Nunes, foi proposto com base em três espécies do Cerrado: M. cerradensis, M. triangularis e M. urbanus. Neste trabalho descrevemos uma nova espécie de Attini do gênero Mycetagroicus, M. inflatus n. sp., baseada em duas operárias coletadas no leste do Pará, Brasil. Apresentamos uma nova chave para a identificação das espécies, comentários sobre as diferenças entre as espécies e novos dados sobre a distribuição geográfica.

The fungus-farming ant genus Mycetagroicus Brandão & Mayhé-Nunes was proposed based on three species from the Brazilian "Cerrado": M. cerradensis, M. triangularis and M. urbanus. Here we describe a new species of Attini ant of the genus Mycetagroicus, M. inflatus n. sp., based on two workers collected in eastern Pará State, Brazil. A new key for species identification, comments on differences among species and new geographical distribution data are furnished.

As formigas cultivadoras de fungos (tribo Attini) são exclusivas da fauna do Novo Mundo. Entretanto, existem poucas informações sobre os padrões de diversidade, abundância e distribuição das espécies de Attini em seus ecossistemas nativos, em especial para os gêneros menos derivados desta tribo. Um levantamento de ninhos de Attini (excluindo Atta Fabricius, 1804 e Acromyrmex Mayr, 1865) foi realizado em diversos ambientes savânicos e de floresta do bioma Cerrado próximos à Uberlândia, Brasil. Encontramos 314 ninhos de 21 espécies pertencentes a nove gêneros da tribo. Trachymyrmex Forel, 1893 foi o gênero mais diverso, com 10 espécies. Encontramos 18 espécies na savana, incluindo Mycetagroicus cerradensis Brandão & Mayhé-Nunes, 2001, uma espécie de um gênero de Attini recentemente descrito, enquanto que nas áreas de floresta registramos somente 12 espécies. As savanas e florestas apresentaram faunas relativamente distintas, com espécies exclusivas de cada tipo de vegetação; as espécies presentes nas florestas não representaram um subconjunto das espécies encontradas nas savanas. Além disso, apesar de muitas espécies terem sido comuns a ambos os tipos de vegetação, suas abundâncias foram muito diferentes. A densidade estimada de ninhos de Attini foi relativamente alta em alguns locais, ultrapassando 4.000 ninhos por hectare. Neste sentido, as formigas da tribo Attini podem ser consideradas como invertebrados predominantes no Cerrado brasileiro.

Fungus-growing ants (tribe Attini) are characteristic elements of the New World fauna. However, there is little information on the patterns of diversity, abundance, and distribution of attine species in their native ecosystems, especially for the so-called "lower" genera of the tribe. A survey of attine ant nests (excluding Atta Fabricus, 1804 and Acromyrmex Mayr, 1865) was conducted in a variety of savanna and forest habitats of the Cerrado biome near Uberlândia, Brazil. In total, 314 nests from 21 species of nine genera were found. Trachymyrmex Forel, 1893 was the most diverse genus with 10 species. Eighteen species were found in the savannas, including Mycetagroicus cerradensis Brandão & Mayhé-Nunes, 2001, a species from a recently-described genus of Attini, whereas in the forests only 12 species were found. Forest and savannas support relatively distinct faunas, each with a number of unique species; the species present in the forest habitats did not represent a nested subset of the species found in the savannas. Furthermore, although many species were common to both types of vegetation, their abundances were quite different. The density of attine nests is relatively high at some sites, exceeding an estimated 4,000 nests per hectare. In this sense, attine ants can be regarded as prevalent invertebrate taxa in the Brazilian Cerrado.

O gênero Mycetarotes inclui quatro espécies de formigas cultivadoras de fungos, exclusivamente encontradas na região Neotropical: M. parallelus (Emery), M. senticosus Kempf, M. acutus Mayhé-Nunes and M. carinatus Mayhé-Nunes. Apresentamos pela primeira vez um resumo sobre as informações disponíveis para as espécies do gênero, fornecendo uma chave para a identificação das operárias, diagnoses e redescrições sinópticas ilustradas das espécies, incluindo as dos alados, quando conhecidos, atualização dos registros de distribuição e fotografias dos ninhos de M. carinatus e M. parallelus. Comentamos a taxonomia e as relações de parentesco entre Mycetarotes e gêneros cognatos, e sobre sua distribuição geográfica. As informações biológicas disponíveis sobre o gênero também foram resumidas.

Mycetarotes is a small genus of the exclusively Neotropical fungus-growing ants, that includes M. parallelus (Emery), M. senticosus Kempf, M. acutus Mayhé-Nunes and M. carinatus Mayhé-Nunes. We hereby revise historical and recent information regarding Mycetarotes species for the first time, providing an identification key to workers, diagnoses, synoptic illustrated redescriptions of the species, including those of sexuals when known, updates of distributional records, and nest pictures of M. carinatus and M. parallelus. We comment the taxonomy and phylogenetic relationships among Mycetarotes and related genera, and on their geographical distribution. The available biological information on the genus is summarized.

As capturas ocorreram entre janeiro e dezembro de 2004 em área urbana de Nova Iguaçu; área rural de Seropédica e em área florestal na Reserva Biológica do Tinguá, Nova Iguaçu, RJ. Foram usadas 1.528 larvas de C. hominivorax como iscas, 505 na área urbana, 556 na rural e 467 na florestal. Foram calculados os índices de Sinantropia, Coeficiente de Constância, o risco (Odds Ratio) de parasitismo entre as áreas, prevalência e intensidade parasitária. O percentual de emergência foi de 46,6%. A espécie A. laeviuscula foi capturada apenas em ambiente rural, seus índices foram: sinantropia = +50, c. constância = 25%, prevalência = 0,72% e intensidade parasitária = 44,5. N. vitripennis foi capturada nas áreas rural e urbana e os índices foram: sinantropia = +98, constância = 58,3%, Odds Ratio = IC95% = 0,025 < µ > 0,27, P < 0,05, prevalência = 3,2% e intensidade parasitária = 7,35. O risco de parasitismo por N. vitripennis em áreas urbanas é alto. Registra-se a ocorrência de A. laeviuscula como parasito de C. hominivorax no estado do Rio de Janeiro.

The captures occurred between January and December of 2004 in urban area in the city of Nova Iguaçu, the rural area of the city of Seropédica and in a forest area in the Biological Reserve of the Tinguá, Nova Iguaçu State of Rio de Janeiro. The total of 1,528 larvae of Cochliomyia hominivorax (Coquerel) were used as bait, 505 in the urban area, 556 in rural and the 467 in the forest one. The indices of Synantropic, Coefficient of Constancy, the risk (Odds Ratio) of parasitism between the areas was calculated, prevalence and parasitic intensity. The percentage of emergence was of 46.6%. Aphaereta laeviuscula (Spinola) was captured only in rural environment; its indices were: Synantropic I. = +50, c. constancy = 25%, prevalence = 0.72% and I. parasitic = 44.5; already Nasonia vitripennis (Walker) was captured in the areas rural and urban and the indices had been: synanthropy = +98, constancy = 58.3%, Odds Ratio = IC95% = 0,025 < µ > 0.27, P < 0,05, prevalence = 3.2% and parasitic intensity = 7.35. The risk of parasitism for N. vitripennis in urban areas is high. The occurrence of A. laeviuscula as parasitic of C. hominivorax is registered in the State of Rio de Janeiro.

Describimos la hembra y el macho de la hormiga neotropical cultivadora de hongos, Mycetarotes carinatus, hasta ahora solo conocida de la localidad-tipo, con base en muestras de obreras. Las formas sexuales fueron obtenidas de un nido criado en laboratorio. Las muestras del estado de Minas Gerais, Brasil, amplían la distribución geográfica de la especie. Ilustramos la arquictetura externa del nido de M. carinatus

We describe the female and male of the Neotropical fungus-growing ant Mycetarotes carinatus, hitherto only known from type locality, Rio de Janeiro state, Brazil, based on samples of workers. The sexual forms were obtained from a nest maintained in the laboratory. The samples found in Minas Gerais state, expand the geographic distribution of the species. We illustrate the external architecture of the nest of M. carinatus

This Work was conducted in Eucalyptus stands at the Itapoã farm of the Mannesmann Fi-El Florestal Ltda. in Paraopeba, MG. The species of fungus growing-ants and leaf-cutting ants found in regrowth areas and in harvesting phase plantings were: Acromyrmex balzani Emery, 1890; Acromyrmex laticeps nigrosetosus Forel 1908; Acromyrmex subterraneus subterraneus Forel, 1893; Atta laevigala (F. Smith, 1858); Alta sexdens rubropilosa Forel, 1908; Mycocepurus goeldii Forel, 1893; Sericomyrmex sp.; Trachymyrmex fuscus Emery, 1894 and three morphospecies of Trachymyrmex Forel, 1893. Taxa belonging to the genus Atta Fabricius, 1804 represented 39.14 and 41.22% of the total number of nests found in the regrowth area and in the harvesting phase plantings, respectively. For Acromyrmex Mayr, 1865 these values were 14.34 and 13.16%; for Trachymyrmex, 40.59 and 30.89%; for Mycocepurus Forel, 1893, 5.34 and 12.50% and Sericomyrmex Mayr, 1865, 0.59 and 2.23% in the regrowth area and in the harvesting phase plantations, respectively.