Hysteropeltella Petr., Annls

Ariyawansa, Hiran A., Kang, Ji-Chuan, Alias, Siti A., Chukeatirote, Ekachai & Hyde, Kevin D., 2013, Towards a natural classification of Dothideomycetes: The genera Dermatodothella, Dothideopsella, Grandigallia, Hysteropeltella and Gloeodiscus (Dothideomycetes incertae sedis), Phytotaxa 147 (2), pp. 35-47 : 42-43

Hysteropeltella Petr., Annls mycol. 21(1/2): 9. 1923.

MycoBank: MB 2470

Saprobic on dead wood and stems in terrestrial habitats. Hysterothecia superficial, solitary or scattered, ellipsoidal and discharging ascospores via a longitudinal slit-like opening. Peridium two-layered, inner layer composed of light brown cells of textura angularis and outer layer composed heavily pigmented cells. Asci 8-spored, fissitunicate, subglobose, oblong to clavate, with a minute pedicel or apedicellate and the apical part of the asci turning blue in Melzer’s reagent. Ascospores fusoid to fusoid-ellipsoidal, hyaline and surrounded by a sheath when immature, eventually becoming light brown at maturity, 1-septate. Asexual state: unknown.

Type species: Hysteropeltella moravica Petr., Annls mycol. 21(1/2): 10. 1923. MycoBank: MB 271649) FIG. 4 A–N

Saprobic on dead wood and stems in terrestrial habitats. Hysterothecia 30–40× 60–70 µm (x = 35× 66 µm, n = 10), superficial, solitary or scattered, ellipsoidal, base flattened, coriaceous, dark brown to black and discharging ascospores via a longitudinal slit-like opening. Peridium 7–15 µm diam (x = 10, n = 10), twolayered, inner layer composed of light brown cells of textura angularis and outer layer composed heavily pigmented cells. Asci 35–45× 15–25 µm (x = 40× 20 µm, n = 20), 8-spored, bitunicate, fissitunicate, subglobose, oblong to clavate, with a minute pedicel or apedicellate, apically rounded with a distinct ocular chamber and the apical part of the asci turning blue in Melzer’s reagent. Ascospores 10–18× 4–6 µm (x = 15× 4 µm, n = 40), irregularly overlapping 3–4-seriate, fusoid to fusoid-ellipsoidal, hyaline and surrounded by a sheath when immature, eventually becoming light brown at maturity, 1-septate, constricted at the septum and without a sheath, wall smooth. Asexual state: unknown.

Notes: Hysteropeltella was introduced by Petrak (1923) and is typified by Hysteropeltella moravica . This monotypic genus is characterized by hysterothecia, with longitudinal slit-like openings, subglobose, oblong to clavate, iodine positive asci and 1-septate ascospores ( Holm and Holm 1978) In his original description, Petrak (1923) did not include the iodine positive reaction of the asci, although it has been observed by later researchers ( Holm and Holm 1978) and as well as in this study. We have noticed two colours of ascospores; when immature they are hyaline with a clear sheath, but eventually turning light brown at maturity without a sheath. This was also observed by Holm and Holm (1978) Petrak (1978) had mentioned pseudoparaphyses surrounding asci, but Holm and Holm (1978) did not observe this character. We could not locate pseudoparaphyses either although this may depend on the maturity of the specimens. Holm and Holm (1978) stated that this species is not conspicuous, even though it is characterized by elongate streaks on the host and hysterothecia open via a longitudinal slit. Holm and Holm (1978) included the genus in Discomycetes, while Lumbsch and Huhndorf (2010) placed in the Dothideomycetes , genera incertae sedis. Hysteropeltella is somewhat similar to the Hysteriaceae and Leptopeltidaceae in possessing hysterothecia opening via a longitudinal slit ( Boehm et al. 2009; Hyde et al. 2013) Hysteropeltella shows similar characters with Schizothyriaceae in processing superficial hysterothecia opening via a longitudinal slit, subglobose, oblong to clavate asci and fusoid to fusoid-ellipsoidal ascospores, but differs from the other genera of Schizothyriaceae in having asci which are apically J+ and hyaline spores with a sheath when immature, eventually becoming light brown at maturity ( Hyde et al. 2013) Therefore we tentatively refer Hysteropeltella in Schizothyriaceae . The generic type needs recollecting, epitypifying and sequencing so that phylogenetic analysis can be used to establish family relationships.

Material examined: Czech Republic, Mähr. Weisskirchen, Podhorn , on Aspidium filix mas , 18 June 1992, F. Petrak (S F5826, holotype)

Figures

FIGURE 4. Hysteropeltella moravica (holotype). A. Herbarium material. B. Appearance of taxon on substrate. C. Close up of the hysterothecium (Note: longitudinal slit-like opening) D. Cross section of ascoma. E. Peridium in section F. Slit-like opening of ascoma. G. Arrangement of asci inside the ascoma. H–K. Asci with 8 ascospores (Note blue staining in Melzer’s reagent) L–N. Immature and mature, smooth-walled ascospores. Scale Bars: D–G = 20 µm, H–K = 15 µm, L–M = 5 µm.