Fungos sapróbios associados a substratos de palmeiras nativas em um fragmento de mata úmida no brejo paraibano

Abstract

Palm trees are home to a diversity of saprobic fungi and have great potential for harboring new species. Biotic and abiotic factors have significant effects on the composition of saprobic fungal communities. The main objective of this study was to evaluate the variation in the composition of fungal communities associated with two native Brazilian palms, Acrocomia intumescens and Attalea oleifera, present in a fragment of wet forest in the Brejo Paraibano, considering the effects of seasonality, substrate type and palm species. During the survey of palm-associated fungi, two new species, Dictyocheirospora acrocomiae sp. nv. and Melanographium sinuosum sp.nv., and two rare fungi, Cheiromyceopsis echinulata and Phragmospathula brachyspathulata, were identified based on their morphological characteristics. The study was conducted in the Mata do Pau Ferro State Park, in Areia, Paraíba, where two collection expeditions were carried out, August/2019 and March/2020. Decaying leaves were collected from three individuals of each palm species and fragments of leaflets and rachis were obtained. The moist chamber technique was used to observe the fungi on the surface of the substrates. A total of 189 specimens of saprobic fungi distributed among 49 species were recorded. The most representative fungi were Neohelicosporium griseum, Piricauda sp., Zygosporium oscheoides, Helminthosporium velutinum and Sporochisma sarccadoi, most of which were associated with Ac. intumescens rachis during the rainy season. Sixteen saprobic fungi were shared between the Ac. intumescens and Att. oleifera palms, with 19 and 16 exclusive fungi, respectively. With regard to substrate, 15 fungi were exclusive to leaflets, 19 were exclusive to rachis and 15 were shared between the two. In the rainy season, a greater number of fungi were exclusive (28) when compared to the dry season (eight), 13 species of fungi were observed in both seasons. The beta diversity analysis showed that palm (F=1.5719, p=0.012), substrate (F=3.3862, p=0.0002) and seasonality (F=1.8676, p=0.0362) significantly influence the composition of saprobic fungi communities, with variations associated with species substitution. Only the interaction between palm and substrate was significant (F=1.5570, p=0.03). Principal coordinates analysis revealed that leaflets and rachises had distinct communities, while rachises of Ac. intumescens and Att. oleifera were similar. Work on mycodiversity is important as it helps to understand local communities, as well as contributing to global species estimates.