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A multigene phylogenetic assessment of North American species of Mallocybe is presented based on analyses of rpb1, rpb2, ITS, and 28S rDNA nucleotide data. This framework enables a systematic revision of the genus for 16 eastern North American species and captures taxonomic and phylogenetic diversity in a global context. A grade of two unusual and poorly known North American species stems from the most recent common ancestor of the genus that gives rise to three core subgroups named here as clades Unicolores, Nothosperma, and Mallocybe. The grade of taxa includes the poorly known Lepista praevillosa from Florida and a new species from the southern Appalachians, M. montana, both of which appear to be narrow-range endemics. Clade Nothosperma is characterized by Australian and New Zealand species, whereas clade Unicolores is composed of six species from eastern North America and East Asia. Clade Mallocybe is dominated by numerous north temperate taxa and constitutes the sister group to clade Nothosperma. These major clades are distinguished by a combination of phylogeny, morphology, geographic distribution, and ecology. In addition, four North American species are described as new: M. leucothrix, M. luteobasis, M. montana, and M. tomentella. Several names originating in North America, long ignored or misunderstood in the literature, are revitalized and established by type comparisons and modern reference material collected from or near type localities. In addition, 11 species were subjected to mass spectrometry muscarine assays, none of which contained detectable amounts of muscarine except for two: M. sabulosa and M. praevillosa. This confirms a diffuse phylogenetic distribution of muscarine within the genus. Taxonomic descriptions are presented for 16 species, several synonymies proposed, and four new combinations made. A key to species of eastern North American Mallocybe is presented, along with illustrations of important diagnostic features.
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Revision of the Late Triassic metoposaurid “ Metoposaurus ” bakeri (Amphibia: Temnospondyli) from Texas, USA and a phylogenetic analysis of the Metoposauridae
Metoposaurids are a clade of large-bodied temnospondyls commonly found in non-marine Late Triassic deposits across northern Pangea. Three taxa are known from North America: Anaschisma browni , Apachesaurus gregorii , and “ Metoposaurus ” bakeri . While the osteology of most metoposaurids has been recently revised, that of a few taxa, including “ Metoposaurus ” bakeri remains poorly characterized. This taxon was formally described in 1931 as “ Buettneria bakeri ,” and its taxonomy has remained in flux ever since then. “ Metoposaurus ” bakeri is the earliest appearing metoposaurid in North America (Carnian of Texas), and Metoposaurus has frequently been utilized as an index taxon of the Otischalkian estimated holochron (‘land vertebrate faunachron’) and for biostratigraphic correlations with other geographic regions. The taxonomy of this species is therefore relevant for both taxonomic experts and biostratigraphers. Here we redescribe all material from the type locality of “ M .” bakeri , the Elkins Place bone bed, and perform a phylogenetic analysis using a revised matrix assembled from several previous studies. Anatomical comparisons and phylogenetic analyses do not support placement in either Metoposaurus , a taxon otherwise only found in Europe, or Anaschisma , the only other large-bodied taxon from North America. Therefore, we erect a new genus, Buettnererpeton gen. nov., to accommodate this species. Metoposaurus is consequently absent from North America, and this genus cannot be used in global biostratigraphy. Phylogenetic analyses provide evidence that the phylogeny of the Metoposauridae remains extremely labile, with drastic differences in topological resolution and structure being linked to just a handful of characters and scores. Metoposaurids’ morphological conservatism and the increased recognition of intraspecific variation thus continue to be major confounds to elucidating the evolutionary history of this clade.
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- Award ID(s):
- 1947094
- PAR ID:
- 10409448
- Date Published:
- Journal Name:
- PeerJ
- Volume:
- 10
- ISSN:
- 2167-8359
- Page Range / eLocation ID:
- e14065
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.7717/peerj.14065
