Crossopsoraceae Aime & McTaggart, fam. nov.
MycoBank number: MB 836646; Index Fungorum number: IF 836646; Facesoffungi number: FoF;
Type genus: Crossopsora Syd. & P. Syd., Annls mycol. 16(3/6): 243. 1919.
Diagnosis: Similar to Phakopsoraceae, differing in that the majority of sporothalli infect Poaceae, Vitaceae, Lamiaceae, and Rhamnaceae with none known on Annonaceae and Euphorbiaceae and that some species are known to be heteroecious.
Description: Spermogonia Group VI (type 7) where known; aecia aecidium-type where known; uredinia typically paraphysate, malupa-type; teliospores germinate externally, with or without dormancy, 1-celled, compact, often produced in catenulate chains of a few to many cells. Most species only known from the sporothallus; Neophysopella is macrocyclic and heteroecious, as may be other species in this family.
Included genera: Angiopsora, Catenulopsora, Crossopsora, Kweilingia (= Dasturella), Neoolivea, Neophysopella, Stomatisora.
Host families: Papaveraceae, Sabiaceae, Rubiaceae (0-I); Lamiaceae, Fabaceae, Poaceae, Rhamnaceae, Rubiaceae, Salicaceae, Vitaceae (II-III).
Notes: Phakopsoraceae sensu Cummins & Hiratsuka (2003) is a polyphyletic family, with multiple polyphyletic genera (Aime 2006, Aime et al. 2018a, 2019a, b, Ji et al. 2019). The phakopsoroid fungi share a convergent suite of characters including pale, subepidermal sori, and 1-celled, sessile teliospores with external germination, which have long been the subject of taxonomic debate, especially concerning application of the names Angiopsora, Bubakia, Phakopsora, and Physopella. Phakopsoraceae s.s. is now confined to species within Raveneliineae on various hosts including Annonaceae, Euphorbiaceae and Fabaceae. The remaining ex- Phakopsoraceae are now placed in Crossopsoraceae (Figs 1, 4), including the species that have radiated on Poaceae and Vitaceae. Some species in both families form teliospores in extruded columns, but these are produced in catenulate chains in Crossopsoraceae, versus tightly packed individual cells in Phakopsoraceae. Life cycles are unknown for many species. However, Neophysopella is heteroecious, alternating either between Sabiaceae and Vitaceae species (Ji et al. 2019) or Papaveraceae and Fabaceae (N. kraunhiae, Hiratsuka & Kaneko 1978); K. divina alternates between Rubiaceae (gametothallus) and Poaceae (sporothallus) (Thirumalachar et al. 1947). Physopella Arthur (1906), although often applied to the species now assigned to Neophysopella and others, is a later homonym of Physopella G. Poirault (1905) and is therefore an illegitimate name (Xi et al. 2019). Our work (Fig. 4) shows that Kweilingia (type K. bambusae, syn. Chrysomyxa bambusae) and Dasturella (type D. divina, syn. Angiopsora divina) are congeneric; Kweilingia (1940) has priority over Dasturella (1943) and we retain these species in the former genus. The phakopsoroid species that form teliospore chains are difficult to diagnose and classify, as exemplified by the complex taxonomic histories of Crossopsora, Cerotelium, Catenulopsora, and Kuehneola (e.g., Ono 2015a). In this work, Crossopsora and Catenulopsora are assigned to Crossopsoraceae. Cerotelium most likely belongs to Phakopsoraceae s.s.; the type, C. canavaliae parasitizes Fabaceae and the uredinia are peridiate in contrast to C. fici with paraphysate uredinia (Cummins 1941). Nonetheless, these genera still appear to be polyphyletic with little support for generic lineages and resolution will require additional taxon and locus sampling (Fig. 4). Numerous Uredo species assigned to Crossopsoraceae, especially within the Crossopsora/Catenulopsora complex, could not be placed in other genera and we have retained use of names in anamorphic form-genera for these. Crossopsora fici and U. moricola form a distinct lineage within Crossopsoraceae and may require a new genus, pending examination of other critical types including those of Mehtamyces, Phragmidiella, Pucciniostele, and Scalarispora.
Fig. 1. Pucciniales. Phylogram obtained from BEAST constrained to a ML topology from three concatenated loci (28S, 18S, and CO3). The tree is rooted with Eocronartium muscicola. Families are indicated by coloured blocks; dashed lines indicate uncertainty at the referenced nodes. Genera represented by types are indicated in bold; genera represented by type proxies (as explained in methods) are indicated by *. Support for nodes is provided from an approximate likelihood ratio test (≥ 0.90), ultrafast bootstraps (≥ 95 %) and genealogical concordance factors for the three loci at each node as aLRT/UFBoot/gCF.
Fig. 4. Uredinineae. ML topography generated from three concatenated loci (28S, 18S, and CO3) with expanded taxon sampling. The tree is rooted with Melampsorineae. Six families are resolved and indicated by coloured blocks; three genera are unresolved to family and indicated as incertae sedis. Genera represented by types are indicated in bold; genera represented by type proxies (as explained in methods) are indicated by *. Support for nodes is provided from an approximate likelihood ratio test (≥ 0.90), ultrafast bootstraps (≥ 95 %) and genealogical concordance factors for the three loci at each node as aLRT/UFBoot/gCF.