Microthyriales » Microthyriaceae

Seynesiella

Seynesiella G. Arnaud, Annals d’École National d’Agric. de Montpellier, Série 2 16 (1–4): 202 (1918) [1917].

Index Fungorum number: IF 5018; Facesoffungi number: FoF 06758, 5 morphological species (Species Fungorum 2022), no molecular data available.

Foliar epiphyte on pinnae of conifers, superficial mycelium absent. Sexual morph: Thyriothecia subglobose, broadly conical or circular, solitary or scattered, superficial, carbonaceous, shiny black to black, lower peridium poorly developed, with a dehiscent stellate central ostiole; in section conical. Upper wall comprising neatly arranged radiating cells. Peridium a single stratum, comprising dark-brown cells of textura angularis. Hamathecium comprising asci and pseudoparaphyses embedded in mucilage inclined toward the central ostiole. Asci 8-spored, bitunicate, fissitunicate, clavate to broad cylindrical, pedicellate, ocular chamber not apparent, not staining blue in IKI. Ascospores overlapping biseriate, ellipsoidal to ovate, ends rounded, hyaline when young, light brown when mature, two celled, the upper cell wider than the lower cell, wall smooth. Asexual morph: Unknown (adapted from Wu et al. 2011).

 Type species: Seynesiella juniperi (Desm.) G. Arnaud

Notes: Seynesiella is characterised by subglobose, broadly conical or circular, solitary thyriothecia, clavate to broad cylindrical, pedicellate asci, and hyaline, ellipsoidal to ovate ascospores with rounded ends. Müller and Arx (1962) treated Seynesiella in Venturiaceae. Barr (1987) considered Seynesiella in Microthyriaceae as closely related to Microthyrium and this was followed by Lumbsch and Huhndorf (2010). Several authors added new species to Seynesiella (Bigelow & Barr 1969, Müller & Arx 1962, Sivanesan & Vánky 2002, Kirk et al. 2008). Seynesiella seems to be related to Microthyrium as both genera have an arrangement of radiating cells in the thyriothecia, bitunicate asci, and two-celled ascospores but differ in that Seynesiella has brown ascospores while Microthyrium has hyaline ascospores (Sivanesan & Vánky 2002). Seynesiella also lacks an ostiole which makes it more typical of Asterinaceae. Seynesiella is currently a distinct genus in Microthyriaceae but lacks molecular data. Fresh collections with DNA sequence data are needed to confirm the taxonomic placement of the genus.

 

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