A re-evaluation of Tubakia, including three new species on Quercus and six new combinations

Abstract

Morphological comparisons and phylogenetic analyses of Tubakia species from leaves of Quercus spp. in Iowa and other areas of eastern USA revealed three novel species: Tubakia hallii, Tubakia macnabbii, and Tubakia tiffanyae. These species, as well as Tubakia dryina and Tubakia iowensis, are common leaf endophytes and pathogens on Quercus and Castanea in eastern USA, as is Tubakia americana comb. nov, originally described from Quercus in New Jersey as Actinopelte americana. New combinations of species on leaves of other hosts in the eastern USA include Tubakia gloeosporioides, Tubakia liquidambaris, and Tubakia nyssae. Asian species of Tubakia are phylogenetically compared, and the new combination Tubakia supraseptata is made to accommodate a Japanese endophyte known only by its sexual state. The earlier description of Dicarpella dryina as the sexual state of T. dryina is questioned. The new combination Tubakia stellata is made to accommodate an unusual species from Brazil.

Phylogeny and taxonomy of the genus Tubakia s. lat.

“…For the LSU and rpb2 alignments, subsets of sequences from the alignments of Senanayake et al (2017) and Fan et al (2018) were used as backbones. For the tef1 alignment, tef1 sequences from Harrington & McNew (2018) were downloaded from GenBank or kindly supplied by the authors when not available in a public database. Loci were aligned with the online version of MAFFT v. 7 (Katoh & Standley 2013) after which the alignments were manually checked and improved where necessary using MEGA v. 7 (Kumar et al 2016).…”

“…A tef1 phylogeny was also generated ( Fig. 5) to enable a more direct comparison of the data in the present paper with the recently published data from Harrington & McNew (2018). The alignment contained 136 isolates and a strain of Melanconis groenlandica (CBS 116540; GenBank accession numbers listed in Table 1) was used as outgroup.…”

“…Conidia were not formed. An ex-type strain (ATTC 58737) was used to retrieve a LSU rDNA sequence (GenBank AF277127, Zhang & Blackwell 2001) which was used by Harrington & McNew (2018) as basis to transfer A. supraseptata to Tubakia. They classified the mycelial colonies in culture to be tubakia-like.…”

“…According to Kaneko & Kobayashi (1984), Apiognomonia has twocelled ascospores in which the top cell is larger than the bottom cell, but in A. supraseptata the top cell is smaller. Harrington & McNew (2018) postulated that A. supraseptata represents the only clearly demonstrated sexual morph of Tubakia. The allocation of Apiognomonia supraseptata to Tubakiaceae is reasonable and could be confirmed in our own analyses ( Fig.…”

“…North American collections assigned to T. dryina are undoubtedly heterogeneous, i.e., T. dryina in North America is a complex of cryptic species (Harrington et al 2012). An important contribution to resolve problems around the diversity of the T. dryina complex in North America has recently been published by Harrington & McNew (2018), including several new species based on US collections. Several Tubakia samples recently collected in Mexico on endemic oaks appear to be morphologically similar to T. dryina but are sufficiently distinct to suggest that they are undescribed species.…”