Mucoharknessia
Mucoharknessia Crous, R.M. Sánchez & Bianchin., Phytotaxa 202(2): 86 (2015)
Facesoffungi number: FoF 01651
Dothideomycetes, order incertae sedis, Botryosphaeriales, Botryosphaeriaceae
Saprobic on the host plant in terrestrial habitat. Sexual morph: undetermined. Asexual morph: Conidiomata dark brown to black, pycnidial, scattered to gregarious or confluent, semi-immersed, globose to subglobose, unilocular or multilocular, glabrous, ostiolate. Ostiole short, circular, centrally located. Conidiomatal wall composed of thick-walled, dark brown to hyaline cells of textura angularis to textura globosa. Conidiophores reduced to conidiogenous cells. Conidiogenous cells arising from the innermost layers of conidiomata, hyaline, lageniform to subcylindrical, determinate, thick- and smooth-walled, with or without percurrently proliferation at apex, with or without flared collarette. Conidia brown or hyaline, ellipsoidal to oval, clavate or subcylindrical, thick- and smooth-walled, or smooth to finely verruculose, lacking striations, unicellular, straight or slightly curved, bearing two kinds type of apical appendage: a) type B, arising from mucilaginous material around developing conidia gradually receding towards conidium apex, hyaline, mucilaginous, irregular, smooth, extracellular (Crous et al. 2015b); b) type C, originating by eversion of partial or full mucoid sheath, widely flared, cup-like, cone-shaped or irregular, extracellular; basal appendage absent or present, tubular, thin-walled, smooth, hyaline, often collapsing.
Type species: Mucoharknessia cortaderiae Crous, R.M. Sánchez & Bianchin., Phytotaxa 202(2): 86 (2015).
Notes: Mucoharknessia was introduced by Crous et al. (2015b) based on M. cortaderiae. The type species is characterized by its conidia, which are brown, oval to ellipsoidal, thick-walled, smooth to finely verruculose, lacking striations, with extracellular apical appendage (type B, see Nag Raj 1993). Li et al. (2016) described a new species M. anthoxanthi Dissan., Camporesi & K.D. Hyde based on phylogeny, but its morphology is similar to tiaropsorella-like species. A phylogenetic tree reconstruction based on LSU, ITS, tef1 and tub2 sequences shows that two fresh collections on Dactylis glomerata from Italy have a close affinity with M. cortaderiae and M. anthoxanthi (Fig. 226). The fresh collections are very similar to M. anthoxanthi, except for conidiomatal structure. The fresh collections have dark brown, rounded, multilocular, papillate conidiomata in a linear series on the host surface, in contrast those of M. anthoxanthi, which were described as scattered to gregarious, unilocular, initially closed, then becoming partly erumpent (Fig. 227 b, c). However, sequences of the new collections are 100% (559/559) similar to M. anthoxanthi in LSU gene region, and differ in four base pairs (including three gaps) in ITS. Based on both phylogeny and morphology, the new collection is regarded as conspecific with M. anthoxanthi. The difference of conidiomatal morphology is thought to reflect the intra-species variation. Two species are accepted in the genus, and a key to the species is provided.
Distribution: Argentina, Italy (Crous et al. 2015b, Li et al. 2016).
References:
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.
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