Asterinales » Asterinaceae

Pycnocarpon

Pycnocarpon Theiss., Abh. K.K. Zool.-Bot. Ges. Wien 7(3): 31 (1913).

Index Fungorum number: IF 4564; Facesoffungi number: FoF 07606, 4 morphological species (Species Fungorum 2022), no molecular data available.

Epiphytes on surface of leaves, black, forming circular or irregular colonies on host surface. Superficial hyphae brown to black, branched, with appressoria, septate, scattered with thyriothecia. Sexual morph: Thyriothecia superficial, flattened, solitary, gregarious, black, circular or irregular, easily removed from the host surface. Asci 2–8-spored, bitunicate, fissitunicate, globose to subglobose, lacking a pedicel. Ascospores overlapping, brown, hyaline with sheath when immature, becoming brown when mature, upper cell wider than lower cell, uniseptate, strongly constricted at the septum. Asexual morph: Unknown (adapted from Doilom et al. 2018).

Type species: Pycnocarpon magnificum (Syd., P. Syd. & E.J. Butler) Theiss.

Notes: Pycnocarpon is characterised by black, circular or irregular colonies, superficial, flattened, solitary thyriothecia, globose to subglobose asci, lacking a pedicel, and overlapping, brownuniseptate ascospores strongly constricted at the septum. Sydow et al. (1911) referred Asterina to Microthyriaceae. Theissen (1913) transferred A. magnificum to Pycnocarpon as P. magnificum in Trichopeltinaceae. Doilom et al. (2018) re-examined the holotype specimen of P. magnificum (S-F46351) and placed Pycnocarpon in Asterinaceae based on morphology of superficial, web-like hypha, flattened thyriothecia opening via a radiating star-like or longitudinal splits, saccate asci and conglobose ascospores, hyaline when young and becoming brown at maturity, uniseptate, strongly constricted at the septum. Doilom et al. (2018) mentioned that Pycnocarpon is typical of Asterina and Pycnocarpon magnificum might be a species of Asterina but this needs confirmation by molecular data. Lumbsch and Huhndorf (2010) and Wijayawardene et al. (2018) listed Pycnocarpon in Dothideomycetes genera incertae sedis. Hongsanan et al. (2020b) accepted Pycnocarpon in Asterinaceae but pointed out that the upper wall of ascomata of Pycnocarpon is different from species of Asterinaceae in having radially arranged, subglobose cells instead of cells of textura prismatica. Sequence data is needed to confirm its placement.

 

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