New endophytic Toxicocladosporium species from cacti in Brazil, and description of Neocladosporium gen. nov

Abstract

Brazil harbours a unique ecosystem, the Caatinga, which belongs to the tropical dry forest biome. This region has an important diversity of organisms, and recently several new fungal species have been described from different hosts and substrates within it. During a survey of fungal endophyte diversity from cacti in this forest, we isolated cladosporium-like fungi that were subjected to morphological and multigene phylogenetic analyses including actA, ITS, LSU, rpb2 and tub2 gene sequences. Based on these analyses we identified two new species belonging to the genus Toxicocladosporium, described here as T. cacti and T. immaculatum spp. nov., isolated from Pilosocereus gounellei subsp. gounellei and Melocactus zehntneri, respectively. To improve the species recognition and assess species diversity in Toxicocladosporium we studied all ex-type strains of the genus, for which actA, rpb2 and tub2 barcodes were also generated. After phylogenetic reconstruction using five loci, we differentiated 13 species in the genus. Toxicocladosporium velox and T. chlamydosporum are synonymized based on their phylogenetic position and limited number of unique nucleotide differences. Six strains previously assigned to T. leucadendri, including the ex-type strain (CBS 131317) of that species, were found to belong to an undescribed genus here named as Neocladosporium gen. nov., with N. leucadendri comb. nov. as type species. Furthermore, this study proposes the actA, ITS, rpb2 and tub2 as main phylogenetic loci to recognise Toxicocladosporium species.

Keywords: Cladosporiaceae; Endophytic fungi; Multigene phylogeny; Taxonomy.

Fig. 1.

Maximum likelihood (RaxML) tree obtained by phylogenetic analysis of the combined ITS and LSU rDNA and rpb2 sequences of 67 taxa belonging to Capnodiales. The new genus, Neocladosporium, is shown in bold. Bootstrap support values from Maximum Parsimony (MP-BS) and Maximum Likelihood (ML-BS), and Bayesian posterior probabilities (BPP) above 70 % and 0.95, respectively, are indicated at the nodes (MP-BS/ML-BS/BPP). Parastagonospora nodorum (CBS 110109) was used as outgroup. ^T = ex-(holo-)type strain, ^ET = ex-epitype strain.

Fig. 2.

Maximum likelihood (RaxML) tree obtained by phylogenetic analysis of the combined ITS rDNA, LSU rDNA, actA, rpb2 and tub2 datasets of the genus Toxicocladosporium. Newly introduced species are shown in bold. Bootstrap support values from Maximum Parsimony (MP-BS), Maximum Likelihood (ML-BS), and Bayesian posterior probabilities (BPP) above 70 % and 0.95, respectively, are indicated at the nodes (MP-BS/ML-BS/BPP). Neocladosporium leucadandri (CBS 131317) was used as outgroup. ^T ex-(holo-)type strain.

Fig. 3.

Neocladosporium leucadendri (CBS 131317 – ex-type culture). A. Colony sporulating on MEA. B–F. Conidiophores giving rise to chains of conidia. Bars = 10 μm.

Fig. 4.

Toxicocladosporium cacti (URM 7489 = CBS 141539 – ex-type culture). A. Colony sporulating on PDA. B. Colony sporulating on OA. C. Colony sporulating on MEA. D–H. Conidiophores and conidia. I. Ramoconidia and conidia. Bars = 10 μm.

Fig. 5.

Toxicocladosporium immaculatum (URM 7491 = CBS 141540 – ex-type culture). A. Colony sporulating on PDA. B. Colony sporulating on OA. C. Colony sporulating on MEA. D. Conidiophores. E–G. Conidiophores and conidia. H. Conidiophore and conidia after 1 mo on SNA at 22 ° C. I. Ramoconidia and conidia. Bars = 10 μm.