A new species of Canalisporium from Australia

Canalisporium variabile sp. nov. is described and illustrated based on several specimens from submerged wood and decaying palm rachis in Australia. It is most similar to C. pallidurn in having pale conidia with clearly visible septa and canals, but they are two distinct species. In C. pallidurn, conidia are more stable in shape, size and septation, with mostly a single column of vertical septa. In C. vam'abile, however, conidia are more variable in morphology, with mostly two columns of vertical septa, and the cells are more constricted. Conidia of C. pallidum are generally longer and more slender than those of C. variabile, which are generally shorter and broader. Canalispom'urn vam'abile is also compared with C. pulchrum and C. kenyense. Kq, Words: dematiaceous hyphomycetes, freshwater fungi, lignicolous fungi, mitosporic fungi, septal pores, systematics In a continuing study of the fungi occurring on submerged wood in tropical streams (Hyde et a1 1998, Lee et al 1998, Wong et al 1999) we collected a previously undescribed species of Canalispom'urn. Canalisporium Nawawi & Kuthub. was introduced to accommodate species of Berkleasmiurn Zobel having complanate conidia with orderly arranged septa in rows and columns and with narrow canals in the septa connecting adjacent cell lumens (Goh et al 1998, Nawawi and Kuthubutheen 1989). The genus has recently been reviewed by Goh et al (1998) and currently comprises six species, namely C. canbense (Hol.-Jech. & Mercado) Nawawi & Kuthub., C. exzgu u m Goh & K. D. Hyde, C. pulchrurn (Hol.-Jech. & Mercado) Nawawi & Kuthub., C. elegans Nawawi & Kuthub., C. kenyense Goh, W. H . Ho & K. D. Hyde, and C. pallidurn Goh, W. H. Ho & K. D. Hyde. .iccepted for p~tblicatiorl ,Januar) 4, 2000. ' Email: tkgohQlik~~cc.hku.hk The new species superficially resembles C. pallid u m in having pale conidia, but differs in the number and arrangement of conidial septa. It is therefore described in this paper as a new species, and compared with C. pallidurn as well as with other species (TABLEI). A composite diagram illustrating conidia of all seven Canalispom'um species is provided to facilitate comparison (see FIGS. 13-21). Canalisporium variabile Goh et K.D. Hyde, sp. nov. FIGS. 1-12, 19-21 Sporodochia in substrato naturali punctiformia, dispersa, atrogrisea, granulata et in humido nitida, hemisphaerica, 200-400 pm lata. Mycelium plerumque in substrato inimersum, ex hyphis ramosis, septatis, subhyalinis, 2-3 pm latis, laevibus, compositum. Conidiophora micronemata vel semi-macronemata, mononemata, fasciculata, simplicia vel sparse ramosa, laevia, hyalina vel subhyalina, usque 20 p+m longa, 1.5-2 p,m lata. Cellulae conidiogenae in conidiophoris incorporatae, terminales, determinatae, cylindricae vel leniter vesiculosae. Conidia 22-35 X 15-23 X 10-10.5 pm, acrogena, solitaria, complanata, laevia, in conspectis superficialibus plus minusve ellipsoidea vel obovoidea, interdum subglobosa vel cubica vel subtriangularia, in conspectis lateralibus cylindrica vel late clavata, fere recta, pallide olivacea vel fla\ldobrunnea, muriformia, plerumque cum septis longitudinalibus biserialis vel raro uniserialis et 2-4(-5) septis transversis in ordinem, non vittatis, tenuis praedita, interduin curn 1-2 septis verticalis additis praedita, ad septa conspicue constricta, lumina cellularum canaliculis conspicue connexa, cellula basali cuneiformia, subhyalina, tenuitunicata, 2.5-5 p+m lata, conidiorurn secessio rhexolytica. Sporodochia on natural substratunl punctiform, scattered, dark gray, granular, glistening when wet, hemispherical, 200-400 km wide (FIGS. 1, 2). Mycelium mostly immersed in the substratum, composed of branched, septate, subhyaline to golden brown, 23 km wide, smooth hyphae. Conidiophores micronematous or semi-macronematous, mononematous, fasciculate, simple or sparsely branched, smooth, hyaline or subhyaline, up to 20 pm long and 1.5-2 km wide. Conidiogenous cells integrated, terminal, determinate, cylindrical, becoming vesiculate as conidia mature (FIG. 5). Conidial secession rhexolytic. Conidia 22-35 X 13-23 X 10-10.5 pm, acrogenous, solitary, one-cell thick and flattened, smooth, variable in shape: in surface klew more or less ellipsoidal or obovoid, sometimes subglobose or cubical to subtrianRGS. 1-12. Canalispcnium variabile, from HOLOTYPE (HKU(M) 7438). 1. Colony on submerged wood. 2. Close-up of wet sporodochia on natural substratum. Note the glistening conidial mass. 3. Conidia with septal canals in focus. 4. A mass of conidia with septa in focus. 5. Squash mount illustrating a mass of vesiculate conidiogenous hyphae with developing and mature conidia. 612. Conidia illustrating a variation of shape, size, and septal arrangement. Bars: 1 = 500 pm, 2 = 200 pm, 3-12 = 10 pm. gular; in lateral view cylindrical or broadly clavate and mostly straight, pale olivaceous to yellowish brown, muriform, usually moderately to strongly constricted at conidial septa and thus the cells appear to bulge in outline; septa unpigmented, thin and septal canals clearly visible, the majority with two columns of vertical septa and 2-4(-5) rows of transverse septa, some with a single column of septa and usually slightly curved, occasionally one or two of the central rows of cells may have additional 1-2 vertical septa, apex comprising a single cell or two to three cells, basal cell cuneiform, subhyaline, thin-walled, 2.5-5 pm wide (FIGS. 3-12, 19-21). Known distribution. Australia. Teleomorph. Unknown. Specimens examined. AUSTRALIA. QUEENSLAND: Atherton Tablelands, Cowry Creek, on wood submerged in creek, 1 May 1998, K D. Hyde, HOLOTYPE: HKU(M) 7438; ibid. HKU(M) 7441; ibid. HKU(M) 7442; ibid. on s u b merged decaying rachis of Oraniopsis appendiculata (Arecaceae), 1 May 1998, K D. Hyde, HKU(M) 8243. Etymology. Variabile, in reference to the conidia, which vary in shape and number and arrangement FIGS.13-21. Conidia of Canalispmiurn spp. drawn to the same scale for comparison. 13. C. rariben~e. 14. C. exiguum. 15. C. pulchrum. 16. C. elegans. 17. C. kenyense. 18. C. pallidurn. 19-21. C. variabile. Bar = 20 pm. T . ~ L . E Comparison of conidial morphology in Canalisporium species (Goh et a1 1998) I.