Bot. Bull. Acad. Sin. (2001) 42: 149-152
Chang — Helicosporous hyphomycetes
Helicoon doliiformis sp. nov. and two similar helicosporous hyphomycetes from Taiwan
H.S. Chang
Institute of Botany, Academia Sinica, Taipei, Taiwan 115, Republic of China
(Received February 29, 2000; Accepted August 4, 2000)
Abstract. Three species of helicosporous (aeroaquatic) hyphomycetes, including a new species Helicoon doliiformis, are described. Helicosporium panacheum is new for Taiwan, and a second record of Xenosporium berkeleyi is given.
Keywords: Helicoon doliiformis; Taiwan.
thickest conidial filament of 8.5-11 µm. Conidiophores are micronematous to semi-macronematous, up to 14 µm, but usually less than that. The conidium coils in a counter-clockwise direction as was reported for H. gigantisporum (Goh and Hyde, 1996). Though conidia coiled only 5-7 times, they reached a height of 70 µm due to the great thickness of their conidial filament.
Another isolate of the genus Helicoon, designated as HTP1101-BB1 (Helicoon sp.), was also obtained from an unidentified decayed twig collected in a stream at Puli, Nantou County. Morphologically, this isolate is very similar to H. doliiformis, but it possesses a thicker conidial filament. The morphological characters of this isolate are as follows:
Helicoon sp. (Figure 1E-F)
Conidiophores semimacronematous, mononematous, cylindrical, erect, straight, short, arising at right angles to the hyphae, light yellowish brown, unbranched, non-septate, smooth, 12-18 µm long, 6.0 µm wide. Conidiogenous cells monoblastic, integrated, terminal, determinate. Conidia solitary, dry, acrogenous, reddish brown when mature but light yellowish brown when still young, helicoid, filament smooth, 9-14 µm thick, tightly coiled 8-9 times in a counter-clockise direction to form a broadly ellipsoidal or doliiform conidium, 80-86 µm long, 58-70 µm wide. Tentatively, we place this isolate in Helicoon doliiformis though its conidia are mostly larger than in this species.
Helicosporium panacheum R.T. Moore, 1954. Mycologia 46: 92. (Figure 2A-E)
Conidiophores macronematous, mononematous, usually unbranched, straight or flexuous, short, light brown, 1-2 septate, 8-38 µm long, 5-6 µm wide. Conidiogenous cells commonly polybastic, terminated by tooth-like projections. Conidia hyaline, white in mass, 24-30 µm in diam. Conidial filament tightly coiled 2.0-2.5 times, multiseptate, 3-7 µm wide.
Introduction
In this paper we report three species of helicosporous hyphomycetes from Taiwan including a new interesting mitosporic fungus of the genus Helicoon. They were observed growing on decayed twigs collected from streams during our survey of freshwater Ascomycetes.
Helicoon doliiformis H.S. Chang, sp. nov. (Figure 1A-D)
Conidiophora semimacronematosa, mononematosa, cylindrica, erecta, recta, non ramosa, non septa, non verrucosa, 8-14 µm longa, 4-6 µm lata. Cellulae conidiogenae monoblasticae, in conidiophoris incorporatae, terminales, determinatae. Conidia solitaria, sicca, acrogena, flavidobrunnea vel atrobrunnea, helicoidea, 42-74 µm longa, 34-70 µm lata. Filamentum 9.5-16.0 µm latum, confertim septa, ellipsoideum vel doliiforme, 4-7 spiris sinistrorsum e centro visis arcte torsivum.
Holotypus: on submerged twig in a small stream, Wulai, Taipei, Taiwan, December 29, 1997, H.S. Chang, IBAS-WL1229-97A1.
Conidiophores micronematous to semimacronematous, mononematous, cylindrical, erect, straight, arising as short branches more or less at right angles to the surface hyphae, unbranched, non-septate, smooth, 8-14 µm long, 4-6 µm wide. Conidiogenous cells monoblastic, integrated, terminal, determinate. Conidia solitary, dry, acrogenous, yellowish to dark brown, helicoid, filament 9.5-16 µm wide, smooth, closely septate, 6-7 septa per coil, no constricted at septa, tightly coiled, 4-7 times in a counter-clockwise direction to form a broadly ellipsoidal or doliiform body, 42-74 µm long, 34-70 µm wide.
Helicoon doliiformis is erected as a new species mainly on the thickness of the conidial filament, ranging from 10 to 17 µm, and 13-15 µm in most cases. It is far thicker than those of known species (Goos et al., 1986; Matsushima, 1993; Van der Aa and Samson, 1994; Goh and Hyde, 1996; Voglmayr, 1997; Abdullah et al., 1998). Helicoon macrosporum had been the species with the
