Polydesmia pruinosa
Polydesmia pruinosa (Berk.&Broome) Boud., IF:119396
Subiculum not typically well-developed, reduced to small amount of anchoring hyphae, observed only near the base of apothecia. Apothecia gregarious, sessile to very short stipitate, pulvinate when young, patelliform to turbinate, 200 µm high when mature; disc finely pruinose, flat to slightly convex, up to 400 µm in diam., pure white to dull white; margin indistinct, not elevated; receptacle finely pruinose, concolorous or paler than the disc. Ectal excipulum not well-defined, textura intricata, of closely interwoven hyphae, 2 to 3 µm thick. Hairs simple or branched, agglutinated, irregularly winding, irregularly curled at the apex, 1.5–2 µm wide, bearing fine granules. Asci c. 8010 µm, cylindrical clavate, stipitate, narrowed to the base, arising from croziers; apex conical, pore strongly MLZ without KOH pretreatment. Ascospores 13.5–24(–37) x 3.5–5.5 µm (19.7 ± 3.3 x 4.2 ± 0.4 µm on average SD, n=35), elongate ellipsoid, straight or slightly curved, 1–3-septate, mostly 3-septate, occasionally containing one large oil globule visible in each cell in MLZ mounts. Paraphyses filiform, flexuous, simple or irregularly branched or strongly coiled at the apex, 1.5 µm wide, having granules at the upper portion, exceeding the asci to give a pruinose appearance to the hymenium.
Specimens examined. HONSHU: TNS-F-12764, Tsukuba University Sugadaira Montane Research Center, Ueda-shi, Nagano Pref. (36°3130.1 N, 138°2049.1 E, alt. 1,346 m), on decaying pyrenomycete, 25–IX–2006. col. T. Hosoya; TNS-F-17785, Idenzawa, Nakagawa, Yamakita-cho, Ashigarakami-gun, Kanagawa Pref. (35°2718.7N, 138°5949.3E, alt. 824 m), on decaying pyronomycete, 3–VII–2005. col. T. Hosoya; TNS-F-24781, Mt. Tsukuba, Tsukubashi, Ibaraki Pref., on decaying pyrenomycete, IX–94. col. T. Hosoya.
Known distribution. Europe, North America, Macaronesia.
Notes. The genus Polydesmia currently consists of eight species (Svrˇ cek, 1967; Korf, 1978, 1981; Raitviir and Galán, 1995; Huhtinen and Santesson, 1997; Zhuang, 1999, 2000). The members of Polydesmia occur on various substrates including fungi, lichens, ferns, herbs, wood and fruits. Polydesmia pruinosa, the type of the genus, is well distinguished from the rest.
Polydesmia pruinosa (TNS-F-12764). A, B. Dried apothecia. Note some in B are coalescent. C. Vertical section of the apothecium. Note the apothecium occurring on black peridium of the pyrenomycete on woody substrate. D. Vertical section at the margin, showing ectal excipulum, hairs and the parahyses. E and F. Asci mounted in MLZ. G. Ascospore. Note oil globules. H. Paraphyses. I. Crozier at the base of the ascus. J. Close up of the ascal apex in MLZ showing MLZ+ reaction at the apex. K. Close up of the paraphyses. Note strongly coiled paraphysis at the right. C and D light microscopy mounted in CB/LA, E–K in MLZ, respectively. Scales. A and B, 0.5 mm; C, 0.1 mm; D–K, 10 µm.
Camera lucida illustration of Polydesmia pruinosa (TNS-F-12764 and TNS-F-17785). A. Asci (TNS-F-12764). B. Paraphyses. The lower two are from TNS-F-17785. C. Ascospores. D. Ascospores, some showing oil globules (TNS-F-17785). E. Ascus apex showing the pore stained in MLZ
References:
Hosoya T. 2009. Enumeration of Remarkable Japanese Discomycetes (3): First Records of Three Inoperculate Helotialean Discomycetes in Japan. Bull. Natl. Mus. Nat. Sci., Ser. B, 35(3), pp. 113–121,
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