Eremomycetales » Eremomycetales genus incertae sedis


Arthrographis G. Cochet ex Sigler & J.W. Carmich., Mycotaxon 4(2): 359 (1976).

Index Fungorum number: IF 7222; Facesoffungi number: FoF 06729, 35 morphological species (Species Fungorum 2022), molecular data available for an unnamed species in the genus.

Pathogenic on plant substrate and human. Sexual morph and trichosporiella-like synasexual morph not reported. Asexual morph: Vegetative hyphae septate, hyaline, smooth- and thin-walled. Conidiophores mostly repeatedly branched, erect, hyaline, smooth-walled. Conidiogenous hyphae simple or laterally branched, thick-walled, forming septa basipetally to form arthroconidia released via schizolytic secession. Arthroconidia unicellular, cylindrical, cuboid or doliiform, straight, hyaline to subhyaline, thick- and smooth-walled. Chlamydospores terminal or intercalary, solitary, unicellular, globose or subglobose, hyaline, rough- and thick-walled, strongly chromophilic (adapted from Giraldo López et al. 2014).

Type species: Arthrographis kalrae (R.P. Tewari & Macph.) Sigler & J.W. Carmich.

Notes: Arthrographis is characterised by simple or laterally branched, thick-walled hyphae, unicellular, cylindrical, cuboid or doliiform, straight, hyaline to subhyaline arthroconidia, and terminal or intercalary, solitary, unicellular, globose or subglobose chlamydospores. Malloch and Sigler (1988) referred Arthrographis in Eremomycetaceae, Dothideomycetes. Several other Arthrographis species were transferred to other genera or classes as they were phylogenetically distant from the type. Arthrographis lignicola was shown to belong to Lecanoromycetes, A. pinicola was transferred to Eremascaceae and A. alba to Gymnoascaceae in Eurotiomycetes (Malloch & Sigler 1988). Eremomyces langeronii was previously reported as the sexual morph of A. kalrae (Arx 1978, Malloch & Sigler 1988). Sigler and Carmichael (1976) validated Arthrographis based on Oidiodendron kalrae. Sigler and Carmichael (1983) considered this sexual and asexual link as doubtful. Gené et al. (1996) agreed with Sigler and Carmichael (1983) and reported that Eremomyces langeronii and A. kalrae produce different RFLP patterns hence, E. langeronii and A. kalrae are not conspecific. Arthrographis resembles members of Pseudeurotiaceae but can be differentiated in that the latter produce brown or olive-brown ascospores and poorly discerned conidiophores sympodially forming subspherical to ovoidal conidia (Giraldo López et al. 2014). Arthrographis sensu stricto differs from Eremomyces and Rhexothecium in having cephalothecoid peridium, dark colored colonies and lack an asexual morph (Malloch & Cain 1971). Among Arthrographis species, A. curvata exhibits both sexual and asexual morphs in culture. The asexual morph of A. curvata resembles Trichophyton in having curved, cashew-nut shaped conidia but differs in that the latter form pycnidium-like conidiomata and cigar-shaped macroconidia in clusters and is phylogenetically distinct as it belongs to Eurotiomycetes (de Hoog et al. 2011, Giraldo López et al. 2014). Numerous ascomycetes have been described with unnamed Arthrographis morphs, for example, Leucothecium coprophilum, L. emdenii and Faurelina indica (Arx & Samson 1973, Arx 1978, Giraldo López et al. 2014). Kang et al. (2010) provided a phylogeny based on SSU, ITS and RPB2 and reported that Arthrographis is polyphyletic. Arthrographis resembles Arthropsis in producing similar arthroconidia (Giraldo López et al. 2014). Arthropsis is characterised by pigmented or non-pigmented arthroconidia fused by nearby connectives, released in a rhexolytic manner from undifferentiated conidiophores and sometimes has Humicola synasexual morph (Sigler et al. 1982, van Oorschot & de Hoog 1984). Van Oorschot and de Hoog (1984) regarded Arthrographis and Arthropsis as very similar and transferred several Arthrographis species to Arthropsis except for the type species A. kalrae. This treatment was not accepted by Malloch and Sigler (1988). Giraldo López et al. (2014) compared the D1/D2 sequences of the available types of Arthrographis and Arthropsis spp. and confirmed the two genera as distinct, with the latter belonging to Sordariomycetes. Giraldo López et al. (2014) reported that the type species, A. kalrae and new taxa A. arxii, A. chlamydospora, A. curvata, A. globosa and A. longispora are restricted to Arthrographis. Arthrographis is currently placed in Eremomycetales genus incertae sedis and may warrant familial rank. Molecular markers available for Arthrographis are ITS, LSU, SSU, Actin, Chitin (CHS1) and RPB2.


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