Hymenoscyphus fructigenus
Hymenoscyphus fructigenus (Bull.) Gray, IF:119009
Apothecia scattered, stipitate with long stipes of various length up to 5 mm long, leathery, yellowish white to dull white when fresh, drying ochraceous (C0M10Y40K0); disc concave to flat 1 mm in diam., flat to cupulate with incurved margin when dry; receptacle smooth when fresh, smooth to a bit fibrous when dry. Ectal excipulum textura prismatica, of thick-walled brickshaped cells of 10–3 x 3–5 µm, arranged parallel to the surface. Medullary excipulum textura intricata, composed of thin-walled hyphae 2 µm wide. Asci 78–125(–150) x 6–8 µm, narrowly cylindrical clavate, stipitate, arising from croziers; apex flattened, thick-walled; pore MLZ+ without KOH pretreatment. Ascospores 15–17(–21) x 3–4 µm (16.5± 3.7 x 3.7± 0.38 µm on average SD, n = 20), elongate ellipsoid, straight, occasionally flattened at one side, aseptate, 1-septate at maturity, rarely having a vestige of a cilium at the lower end. Paraphyses filiform, flexuous, sometimes branched, up to 2.5 µm wide, even in width.
Specimens examined. HONSHU: TNS-F- 15233, Sugadaira Pasture, Sugadaira, Ueda-shi, Nagano Pref., on decaying acorns of Quercus, 25–IX–2006, col. T. Hosoya; TNS-F-24796, Miyori, Fujiwara-machi, Tochigi Pref., on decaying acorns of Quercus, 29–IX–1997, col. Y. Ono.
Known distribution. Europe, North America, Asia.
Notes. This is the lectotype species selected by Dennis (1964) for the genus Hymenoscyphus. Hymenoscyphus fructigenus occurs on acorns and nuts of various trees, wood and twigs of broad-leaved trees and shrubs, and cones of conifers. It is common on acorns of Quercus in central Japan. Lizon (1992) pointed out that ascospores are rarely one-septate. However, in the present specimens, septation occurs frequently while within the asci, and often become one-septate prior to germination. Lizon (1992) described morphological difference based on collection sites.
Hymenoscyphus fructigenus (TNS-F-15233). A. Dried apothecia. B. Vertical section of an apothecium. C. Close up of the ectal excipulum composed of thick-walled prismatic cells. D. Close up of the medullary excipulum. E. Close up of the apothecium at the margin showing the ectal and medullary excipulum. F. Asci and paraphyses. G. Ascus. H. Ascospores. Note some of them are one septate. Scales. A, 1 mm; B, 50 µm; C–E, 10 µm. B–E light microscopy mounted in CB/LA, F–H in MLZ, respectively
Camera lucida illustration of Hymenoscyphus fructigenus (TNS-F-15233). A. Ascospores. Note one at the top left having short vestige of a cilium. B. Paraphyes. C. Asci. D. Vertical section of the apothecium at the margin showing the ectal excipular structure. 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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