Additions to the knowledge of hydnoid Steccherinaceae: Cabalodontia, Etheirodon, Metuloidea, and Steccherinum.

The family Steccherinaceae includes genera with smooth, hydnoid, and poroid hymenophores, monomitic to dimitic hyphal systems, and generative hyphae with clamps or simple septa. Steccherinum is the largest genus in the family, with a worldwide distribution, and is characterized mainly by a dimitic hyphal system and presence of thick-walled encrusted cystidia. Species traditionally included in Steccherinum, however, have been transferred to other genera based on results of molecular phylogenetic analyses. Even though knowledge of Steccherinaceae has increased in the past few years, very little is known about the hydnoid species of the family, especially from the Neotropics. In this study, we present morphological and phylogenetic analyses on hydnoid specimens of Steccherinaceae collected in the Neotropics. Molecular data of nuc internal transcribed spacer region ITS1-5.8S-ITS rDNA (ITS) and portions of nuc 28S rDNA (28S), translation elongation factor 1-α (tef1), and the largest subunit of RNA polymerase II (rpb1) were obtained from Brazilian collections. Types and original collections were studied for morphological comparison. Samples we studied grouped in four different genera of Steccherinaceae: Cabalodontia, Etheirodon, Metuloidea, and Steccherinum. Three new neotropical species, Cabalodontia delicata, Etheirodon purpureum, and Steccherinum larssonii, are described. In addition, the new combinations Cabalodontia albofibrillosa and Metuloidea reniformis are proposed. The four genera presented in this study are compared and discussed in detail.

An overview of Antrodiella and related genera of Polyporales from the Neotropics.

The genus Antrodiella includes resupinate and pileate species of polypores with a dimitic hyphal system, small, globose to cylindrical basidiospores, absence of cystidia, tetrapolar mating system, and haplo-dikaryotic nuclear behavior. Recent studies, however, indicate that Antrodiella is highly polyphyletic, so many of its species have been transferred to other genera. This study reviews the systematic status and diversity of Antrodiella from the Neotropics based, in part, on studies of type specimens. Collections from Brazil were used for molecular analysis of nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS), nuc 28S rDNA (28S), and portions of genes encoding translation elongation factor 1-α (tef1) and the second largest subunit of RNA polymerase II (rpb2). Eight genera are confirmed to include Neotropical species treated as Antrodiella in a broad sense: Aegis, Antrodiella s. str., Flaviporus, Metuloidea, Mycorrhaphium, Rickiopora, Trametopsis, and Trullella. Molecular data reveal the occurrence of two new species, described as Antrodiella trivialis, the only Neotropical species of Antrodiella s. str. known so far, and Mycorrhaphium hispidum. In addition, Antrodiella luteocontexta was found to nest in the genus Aegis, close to the Grifolaceae and Polyporaceae; therefore, the new combination Aegis luteocontexta is proposed. Comments on the eight Antrodiella-related genera as well as species with uncertain taxonomic position are provided, together with a key to their identification.

Extensive characterization of the new genus Rickiopora (Polyporales).

Ceriporiopsis latemarginata and Antrodiella angulatopora are two Neotropical polypores that are very similar morphologically and are characterized by effused-reflexed basidiomes, large angular pores, small ellipsoid to ovoid basidiospores and a monomitic hyphal system with presence of thick-walled hyphae with infrequent clamps. In order to verify the evolutionary relations of C. latemarginata and to find its taxonomic placement, morphological, biological, and phylogenetic studies were carried out, as well as comparisons with Antrodiella s.s. and Ceriporiopsis s.s. Mono- and poly-sporic cultures were obtained and used for mating system and nuclear behaviour studies, as well as for DNA sequence analyses of the internal transcribed spacer and large subunit of ribosomal RNA gene, translation elongation factor 1-alpha gene and RNA polymerase II second largest subunit-like gene. Type specimens of C. latemarginata and A. angulatopora were morphologically examined and their synonymy was confirmed. The results obtained support the description of a new polypore genus Rickiopora in the residual polyporoid clade characterized by a bipolar mating system, an astatocoenocytic nuclear behaviour, and a monomitic hyphal system that display a metachromatic reaction in cresyl blue.

Influence of caffeine on the survival of leaf-cutting ants Atta sexdens rubropilosa and in vitro growth of their mutualistic fungus.

BACKGROUND: Leaf-cutting ants collect plant fresh material for the cultivation of their mutualistic fungus. Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae) cause great economic losses through their foraging activity, mainly in agriculture. The main control method is the application of granulated toxic baits incorporated with an active ingredient (AI). The present goal is to evaluate the effect of caffeine on in vitro growth of the mutualistic fungus and on the survival of the leaf-cutting ants, aiming to verify the potential toxicity of this secondary metabolite over these organisms. RESULTS: Three distinct patterns of fungal growth correlated with caffeine concentration were observed: (1) no effect (0.01% caffeine); (2) intermediate growth reduction (0.05% caffeine); (3) drastic growth reduction (0.10 and 0.50% caffeine). The highest caffeine concentration causes fungus death in the first week. As for insect survival, caffeine does not seem to exert any effect. The treatments with diet containing caffeine showed similar values of M50, irrespective of caffeine concentration. CONCLUSION: As caffeine was shown to reduce growth of the mutualistic fungus of Atta sexdens rubropilosa, but with no conclusive effect on insect survival, a hypothetical explanation for the selection of different Coffea species by this leaf-cutting ant species might be associated with caffeine toxicity to the fungus.