478 Mycol. Res. 104 (4) : 478–485 (April 2000). Printed in the United Kingdom. Lignicolous freshwater Ascomycota from Thailand : Melanochaeta and Sporoschisma anamorphs Somsak SIVICHAI, Nigel L. HYWEL-JONES and Sayanh SOMRITHIPOL National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 73}1 Rama VI Road, Rajdhevee, Bangkok 10400, Thailand. Accepted 26 June 1999. Two species of Melanochaeta and three species of Sporoschisma are reported from Thailand. Two connections of Sporoschisma and Melanochaeta are confirmed. Melanochaeta hemipsila has Sporoschisma saccardoi as its anamorph with a Chalara synanamorph in culture. Melanochaeta garethjonesii is described as a new species and linked with S. uniseptatum. S. nigroseptatum was recorded but no evidence of a Melanochaeta teleomorph state could be found. INTRODUCTION MATERIALS AND METHODS The poorly known genus Melanochaeta was described from rotten wood in a variety of habitats and currently includes two species. Barr (1990) considered it to be of ‘ southern hemispheric ’ distribution based on records at that time and ‘ with ascospores having brown mid cells and hyaline end cells much as in Litschaueria.’ Mu$ ller et al. (1969) connected M. hemipsila with the dematiaceous Sporoschisma describing S. saccardoi from cultural work. Mu$ ller & Samuels (1982) demonstrated the relationship between M. aotearoae and S. mirabile, and noted that ‘ although the connections between these ascomycetes and their anamorphs has been demonstrated in pure culture, the morphological similarities between the sexual and asexual stages are so great, however, as to render cultural proof of the connection almost superfluous ’. Significantly, Mu$ ller & Samuels (1982) were the first to report the production in culture of a Chalara synanamorph. Most recently, Goh et al. (1997) gave a synopsis of Sporoschisma from Hong Kong and noted that although there have been more than thirteen species named there are now only seven accepted species. We are currently studying the colonization of wood in rivers and seeds in the leaf litter of natural forests in Thailand. In the course of this work, three species of Sporoschisma and two species of Melanochaeta were found. These were isolated and connections between Melanochaeta hemipsila, S. saccardoi and the Chalara synanamorph are reported. Melanochaeta garethjonesii is described as a new ascomycete, and is linked with the anamorph S. uniseptatum. In addition, records are provided on the development of S. nigroseptatum which has no known teleomorph. For the study on colonization of woods in rivers the methods used have been described previously (Sivichai et al., 1998 a ; Sivichai, Hywel-Jones & Jones, 1998 b). For work on seed fungi we collected a variety of seeds in various states of decay from the forest floor. They were cleaned of soil and associated debris and incubated in plastic pots in a humid chamber. Seeds were examined regularly for the presence of fungi, which were then isolated using the same general methods as described by Sivichai et al. (1998 a, b). Unless mentioned otherwise, collections were from the Khao Yai National Park. TAXONOMY Melanochaeta hemipsila (Berk. & Broome) E. Mu$ ll, Harr & Sulmont, Revue de Mycologie 33 : 377 (1969). Figs 1–17 Anamorph : Sporoschisma saccardoi E. W. Mason & S. Hughes, Mycological Papers 31 : 20 (1949). Colonies effuse, black, hairy, composed of ascomata with mixed tufts of conidiophores (Fig. 1). Ascomata solitary, scattered, superficial, anchored to substrate by an indistinct basal stroma, broadly pyriform, 350–560 µm high and 300–460 µm wide, not collapsing when dry ; wall smooth and shining, covered with stiff, erect, dark brown to black setae each with a slightly swollen, light brown to colourless cap ; up to 300 µm long¬5–7±5 µm wide. Paraphyses filiform, septate, longer than asci, hyaline. Asci unitunicate, cylindrical to narrow clavate, 185–220¬12±5–20 µm, apex with a refractive, non-amyloid ring, eight-spored (Figs 2–3). Ascospores partially biseriate, fusiform 30–40¬7±5–10 µm with five transverse S. Sivichai, N. L. Hywel-Jones and S. Somrithipol 479 1 4 2 5 6 3 7 8 Figs 1–8. Melanochaeta hemipsila and its anamorph Sporoschisma saccardoi. Fig. 1. Ascomata (arrowed) and conidiophores on test block ; Fig. 2. Apical apparatus of ascus ; Fig. 3. Immature asci ; Fig. 4. Ascospores ; Figs 5–6. Conidiophores with capitate setae (arrowed) ; Fig. 7. Chain of conidia ; Fig. 8. Conidia. Scale bars : Fig. 1 ¯ 200 µm ; Figs 2–4, 8 ¯ 10 µm ; Figs 5, 6 ¯ 50 µm. septa (rarely four or six septa), curved, central four cells darker brown and larger than the lighter brown end cells (Fig. 4). Conidiophores with sterile capitate setae arising from a bulbous stroma up to 75 µm diam (Figs 5–6) ; setae pale brown, paler toward apex, straight or slightly flexuous, one to four septate, 115–130 µm long and 5–6 µm wide below the terminal swelling which is 10–12±5 µm wide and sub-hyaline ; conidiophores solitary or in groups of two or three, also arising from stroma, often with one or two, sometimes up to four, capitate setae, 185–260 µm long, 10–12 µm at the base, 10–15 µm wide at the swollen middle part, neck 12±5–17±5 µm wide, dark brown, paler at the torn apex. Conidia formed enteroblastically inside the tubular collarette of the conidiogenous cell, elongate doliiform, 27±5–47±5¬11±5–15 µm, fiveseptate, often constricted at the septa the four inner cells dark brown and the two end cells much paler, shorter and somewhat truncate, giving the appearance of constriction between successive conidia of a chain (Fig. 7) ; the two central cells 7–9 µm long, penultimate cells 6±5–9 µm long (Fig. 8). Ascospores and conidia germinating on CMA within 36 h with cool, white fluorescent light at 20°, producing a germ tube from either one or both ends or from the middle cell. Colonies on CMA reaching 15–20 mm diam. in 20 d at 20° in cool, white fluorescent light, diffuse, effuse with hyaline mycelium (Figs 9–11). Mycelium partly immersed, partly superficial, branched, septate, hyphae to 3 µm wide. Sporulation after 20 d profuse throughout the colony, more crowded in the centre. Sporoschisma conidiophores and Chalara state either solitary or arising together with capitate hyphae in scattered fascicles of a few (Figs 12–14). Sporoschisma conidiophores arising with capitate hyphae, macronematous, unbranched, black, smooth, cylindrical, abruptly narrowed at the base 160–240 µm long, 9–12 µm wide at the base, 9–13 µm wide at the swollen middle part. Conidia catenate, extruded in long chains, 22±5–40¬10–15 µm, not constricted at the septa, five-septate, some three- or four-septate, four inner cells much darker than the two hyaline to pale brown end cells. Chalara conidiophores macronematous, unbranched, pale brown, smooth, tapering gently and uniformly from base to tip, 0–2(–6) septate, 25–35(–150) µm long, 3±8–5 µm wide across the venter, narrowing to 2–3±5 µm at the collarette (Figs 15–16). Conidia catenate, extruded in long fragmenting chains, 2±5–3¬2–2±5 µm, cuboid with truncate ends, rarely rectangular, non-septate, sub-hyaline to pale brown (Fig. 17). Melanochaeta and Sporoschisma 9 480 10 11 14 15 16 12 13 17 Figs 9–17. Sporulation of Melanochaeta hemipsila on CMA. Fig. 9. Colony sporulating after 20 d ; Figs 10–11. Sporoschisma anamorph and Chalara synanamorph ; Figs 12–13. Conidiophores of the Sporoschisma anamorph with capitate setae ; Fig. 14. Chalara synanamorph with Sporoschisma anamorph at the base ; Figs 15–16. Chalara synanamorph arising from mycelium ; Fig. 17. Chalara conidia. Scale bars : Fig. 9 ¯ 3 mm ; Figs 10, 11 ¯ 200 µm ; Figs 12, 13 ¯ 20 µm ; Figs 14–17 ¯ 10 µm. Specimens examined : Teleomorph : Thailand : Nakorn Ratchassima Province, on twig, 25 Sep. 1996, Sivichai (SS109) ; Prachin Buri Province, stream at km 29±2, on wooden test block (Alstonia scholaris) submerged 4 mo, 8 Jan. 1997, Sivichai (SS244) ; Prachin Buri Province, stream at km 29±2, on wooden test block (Anisoptera oblonga) submerged 5 mo, 4 Feb. 1997, Sivichai (SS316) ; Nakorn Ratchassima Province, Mor Singh To – Nicola’s gibbon research trail, on seed pod of Entada sp. (Leguminosae), 10 Jun. 1998, Somrithipol (SFC274). Anamorph : Thailand : Petchabun Province, Chulaporn Dam, on twig, 1 Oct. 1996, E. B. G. Jones & Sivichai (SS26) ; Nakorn Ratchassima Province, on twig, 25 Sep. 1996, Sivichai (SS108) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. oblonga) submerged for 1 mo, 14 Oct. 1996, Sivichai (SS163) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. scholaris) submerged for 2 mo, 14 Nov. 1996, Sivichai (SS166) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. scholaris) submerged for 4 mo, 8 Jan. 1997, Sivichai (SS245) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. oblonga) submerged for 1 mo, 27 Feb. 1997, Sivichai (SS269) ; Nakorn Ratchassima Province, on legume pod (Entada sp.), 7 Oct. 1997, Somrithipol (SFC15) ; Songkhla Province, Prince of Songkhla University, on pod (Hevea brasiliensis), 9 Dec. 1997, Somrithipol (SFC40) ; Surat Thani Province, Khao Sok National Park, on pod (Hevea brasiliensis), 29 Oct. 1998, Somrithipol (SFC260) ; Nakorn Ratchassima Province, on legume pod (Entada sp.), 10 Jun. 1998, Somrithipol (SFC274). S. Sivichai, N. L. Hywel-Jones and S. Somrithipol 481 18 19 20 22 21 23 Figs 18–23. Melanochaeta garethjonesii. Figs 18–19. Ascomata on test block ; Fig. 20. Apical apparatus of ascus ; Fig. 21. Squash of asci and paraphyses ; Fig. 22. Immature and mature asci ; Figs 23. Ascospores. Scale bars : Figs 18, 19 ¯ 200 µm ; Figs 20, 23 ¯ 10 µm ; Fig. 21 ¯ 100 µm ; Fig. 22 ¯ 20 µm. Cultures examined : Isolated from the teleomorph : SS316, SFC274 ; isolated from the Sporoschisma anamorph : SS26, SS548, SFC16, SFC40 and SFC260. All cultures are stored in the BIOTEC National Culture Collection. Distribution : Teleomorph : Australia (Hyde, pers. comm.), French Guiana, Sri Lanka and Thailand. Anamorph : Australia, Brunei Darussalam, Canada, Ecuador, Hong Kong, Indonesia, Italy, Malaysia, Peru, South Africa, Taiwan and Thailand. Melanochaeta garethjonesii Sivichai & Hywel-Jones, sp. nov. Figs 18–35 Etym. : In recognition of the support Professor E. B. G. Jones has given to all three authors. Anamorph : Sporoschisma uniseptatum Bhat & W. B. Kendr., Mycotaxon 49 : 71 (1993) Ascomata solitaria, dispersa, superficialia, late pyriformia, atrobrunnea, 400–540 longa, 340–440 µm crassa statu anamorpho. Peridium nitens, laeve ; setis. Setae rigidae, erectae, non-ramosae, atro-brunneae vel atrae, capitatae. Paraphyses filiformes, septatae, hyalinae. Asci cylindrici vel ad anguste clavati, 165–225 longa, 12±5–20 µm crassa, octo-spori, unitunicati. Ascosporae partim biseriatae ad biseriatae, fusiformes, pallidae brunneae, leviter curvae ; 4 septa transversa, 32±5–45 longa, 6–7±5 µm crassa. Coloniae anamorphae effusae, sparsae. Conidiophora mononemata, plerumque 2–5, rigida, erecta vel flexuosa, cylindrica, 135–190 µm longa 12±5–15 µm crassa ; inflato medio. Conidia cylindrica, truncata, leviter verruculosa, plerumque 1-septata, raro 2- vel 3-septata, 17±5–25 longa, 10–15 µm crassa, pallentia brunnea. Holotypus : Thailand : Prachin Buri Province, Khao Yai National Park, stream at km 29±2, on wooden test block (A. scholaris) submerged for 11 mo, 12 Aug. 1997, Sivichai SS481 (holotype BIOTEC National Fungus Herbarium). Colonies black, composed of conidiophores and ascomata with capitate setae (Figs 18–19). Ascomata solitary, scattered, superficial, anchored to the substrate by an indistinct basal stroma, broadly pyriform, 400–540 µm high and 340–440 µm wide, ascomata not collapsing when dry ; wall smooth and shiny, covered with stiff, erect unbranched, dark brown to black setae, to 100 µm long, 5–6 µm wide, capitate, arising from all over surface of ascomatal wall, each with a slightly Melanochaeta and Sporoschisma 482 24 25 26 28 27 Figs 24–28. Sporoschisma uniseptatum. Fig. 24. A representative portion of the colony on test block. Note the long chains of adhering conidia ; Fig. 25. Apical portion of phialides ; Fig. 26. Conidiophores with basal setae and conidial chain ; Fig. 27. Chain of conidia ; Fig. 28. Conidia. Scale bars : Fig. 24 ¯ 100 µm ; Figs 25, 27, 28 ¯ 10 µm ; Fig. 26 ¯ 50 µm. swollen, light brown to colourless cap. Paraphyses filiform, to 4 µm wide, septate, longer than asci, hyaline (Fig. 21). Asci cylindrical to narrowly clavate 165–225¬12±5–20 µm, unitunicate, apex with a refractive, non-amyloid ring, eightspored (Figs 20–22). Ascospores partially biseriate to biseriate, fusiform 32±5–45¬6–7±5 µm, predominantly four-septate (rarely three or five), pale brown, slightly curved (Fig. 23). Anamorph colonies effuse, black, sparse (Fig. 24). Conidiophores mononematous, differentiated. Setae present, capitate, erect, straight or flexuous, three to six septate, smooth, pale brown, paler towards the sub-hyaline apex, to 140 µm long, 12±5–15 µm wide, with hyaline mucilage around swollen apex ; conidiophores mostly in groups of two to five associated with capitate setae, erect, straight or flexuous, cylindrical, 135–190¬7±5–10 µm wide at the base, 12±5¬17±5 µm wide at the swollen middle part and 12±5–15 µm wide at the venter (Figs 25–26, 32–34). Conidia catenate, cylindrical, truncate at both ends, slightly verruculose, predominantly one-septate, rarely two or three-septate, pale brown, uniform in colour, 17±5–25¬10–15 µm (Figs 27–28, 35). Ascospores germinating on CMA within 36 h with cool, white fluorescent light at 20°, producing a germ tube from one or both ends (Fig. 31). Conidia germinating on CMA within 36 h with cool, white fluorescent light at 20°, producing a germ tube from one cell or both end cells. Colonies on CMA reaching 15–20 mm diam in 20 d at 20° in cool, white fluorescent light, diffuse, effuse with hyaline mycelium. Mycelium partly immersed, partly superficial, branched, septate, hyphae to 3 µm wide (Fig. 29). Sporulating after 14 d (Figs 29–30). Specimens examined : Teleomorph : see holotype. No other collection known. Anamorph : Thailand : Prachin Buri Province, stream at km 29±2, on wooden test block (Alstonia scholaris) submerged for 2 mo, 14 Nov. 1996, Sivichai (SS102) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. scholaris) submerged for 4 mo, 8 Jan. 1997, Sivichai (SS134) ; Nakorn Ratchassima Province, stream at Tad Ta Phu, on wooden test block (A. scholaris) submerged for 4 mo, 8 Jan. 1997, Sivichai (SS141) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. scholaris) submerged for 5 mo, 4 S. Sivichai, N. L. Hywel-Jones and S. Somrithipol 483 29 30 31 32 33 34 35 Figs 29–35. Sporulation of Melanochaeta garethjonesii on CMA. Fig. 29. Colony sporulating after 14 d ; Fig. 30. Sporulation ; Fig. 31. Germination of ascospores on CMA after 36 h ; Figs 32–34. Squash of Sporoschisma conidiophores ; Fig. 35. Conidia. Scale bars : Fig. 29 ¯ 10 mm ; Fig. 30 ¯ 1 mm ; Figs 31–34 ¯ 100 µm ; Fig. 35 ¯ 50 µm. Feb. 1997, Sivichai (SS193) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. oblonga) submerged for 5 mo, 4 Feb. 1997, Sivichai (SS202) ; Nakorn Ratchassima Province, stream at Tad Ta Phu, on wooden test block (A. scholaris) submerged for 5 mo, 4 Feb. 1997, Sivichai (SS208) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. scholaris) submerged for 6 mo, 27 Feb. 1997, Sivichai (SS263) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. oblonga) submerged for 4 mo, 8 Jan. 1997, Melanochaeta and Sporoschisma 484 36 38 37 39 Figs 36–39. Sporoschisma nigroseptatum : Fig. 36. A representative portion of the colony on test block ; Fig. 37. Apical portion of phialides ; Fig. 38. Conidiophores and setae ; Fig. 39. Conidia. Scale bars : Fig. 36 ¯ 1 mm ; Figs 37, 39 ¯ 10 µm ; Fig. 38 ¯ 50 µm. Sivichai, (SS312) ; Nakorn Ratchassima Province, stream at Tad Ta Phu, on wooden test block (A. scholaris) submerged for 7 mo, 10 Apr. 1997, Sivichai (SS334) ; Prachin Buri Province, stream at km 29±2, on wooden test block (A. scholaris) submerged for 11 mo, 12 Aug. 1997, Sivichai (SS482) ; Nakorn Ratchassima Province, stream at Tad Ta Phu, on wooden test block (A. scholaris) submerged for 11 mo, 12 Aug. 1997, Sivichai (SS483) ; Satun Province, Thaleban National Park, on legume pod, 11 Dec. 1997, Somrithipol (SFC 127) ; Songkhla Province, Ton Nga Chang wildlife Sanctuary, on legume pod, 13 Nov. 1997, Somrithipol (SFC 172). Cultures examined : Isolated from the teleomorph : SS481 ; isolated from the Sporoschisma anamorph : SS102, SS134, SS141, SS481 (¯ SS482), SS483, SFC127 and SFC172. All cultures are stored in the BIOTEC National Culture Collection. Distribution : Teleomorph : Thailand, type locality. Anamorph : India, Seychelles and Thailand. Sporoschisma nigroseptatum D. Rao & Rao, Mycopathologia et Mycologia Applicata 24 : 82 (1964). Figs 36–39 Teleomorph : unknown. Colonies effuse, black, hairy (Fig. 36). Setae sparse, capitate, erect, straight or flexuous, 0–3 septate, smooth, pale brown, paler towards the sub-hyaline apex, up to 150 µm long, 5–6 µm wide, sometimes proliferating once percurrently ; swollen apex 8–10 µm wide, surrounded by mucilage. Conidiophores mainly solitary or in groups of two to three, each with zero to two setae, erect, straight or flexuous, cylindrical, 300–400 µm long, 8–12±5 µm wide at the base, 18–24 µm wide at the swollen middle part, thick-walled, smooth, dark brown (Figs 37–38). Conidiogenous cells monophialidic, terminal, integrated, lageniform, consisting of a slightly swollen venter 16–20 µm wide, frayed at the apex. Conidia catenate, elongate doliiform, sub-truncate at both ends, 35–45¬12±5–15 µm, five septate, with four inner cells dark brown and the two end cells hyaline to pale brown, septa thick, the inner three septa 2±5–3±5 µm thick, the two distal septa ca 1±5–2 µm thick, the two central cells (7±5–10 µm) are longer than the penultimate cells (5–6 µm) (Fig. 39). Conidia germinating on CMA within 48 h with cool, white fluorescent light at 20°, producing a germ tube from both end cells or from the middle cells. Colonies on CMA reaching 15–20 mm diam. in 30 d at 20° in cool, white fluorescent light, diffuse, effuse, hyaline mycelium with aerial hyphae. Mycelium partly immersed, partly superficial, branched, septate, hyphae up to 3 µm wide ; colony becoming black with a ring of sporulation after 14 d, conidiophores more crowded in the middle. Specimens examined : Thailand : Nakorn Ratchassima Province, stream at Tad Ta Phu, on wooden test block (A. oblonga) submerged for 4 mo, 8 Jan. 1997, Sivichai (SS311) ; Nakorn Ratchassima Province, stream at Tad Ta Phu, on wooden test block (A. scholaris) submerged for 8 mo, 6 May 1997, Sivichai (SS485). Cultures examined : Isolated from the anamorph : SS311 and SS485, deposited in the BIOTEC National Culture Collection. Distribution : Australia, Hong Kong, India, Japan, New Zealand and Thailand. S. Sivichai, N. L. Hywel-Jones and S. Somrithipol 485 Table 1. Species of Sporoschisma and their known teleomorphs. Teleomorph Sporoschisma anamorph Chalara synanamorph Ascomata (µm) Asci (µm) Ascospores (µm) Ascospore septa M. hemipsila M. aotearoae M. garethjonesii S. saccardoi S. mirabile S. uniseptatum Present Present Absent 350–560¬300–460 240–470¬220–400 400–540¬340–440 184–200¬12±5–20 170–230¬10–13 165–225¬12±5–20 30–40¬7±5–10 23–30¬7–10 32±5–45¬6–7±5 5 3 4 DISCUSSION Melanochaeta garethjonesii has larger ascomata and bigger asci than M. aotearoae (Table 1). Although ascomata, asci and ascospores have similar sizes to those of M. hemipsila, there are significant differences in the ascospore colour and number of septa (Table 1). Importantly the ascospores of M. garethjonesii are a uniform brown whereas those of M. hemipsila have pale end cells. The most significant difference between the three species, is in the anamorph. Although the Sporoschisma state of M. hemipsila appears to have a pan-global distribution the teleomorph is known only from a few scattered tropical or subtropical records. Furthermore, these records are mostly from the Asia–Pacific region, although it has been reported from French Guiana (Courtecuisse et al., 1996). Mu$ ller & Samuels (1982) note that Sporoschisma ‘ is characterised by cylindrical, monophialidic conidiophores ; integrated, tubular phialides ; pale brown to nearly black, cylindrical, catenate, phragmoconidia and erect setae, each of which has a somewhat swollen tip that is enclosed with mucilaginous material ’. Mu$ ller & Samuels (1982) found that Melanochaeta aotearoae is synanamorphic, producing a Sporoschisma with a Chalara state in culture. Nag Raj & Kendrick (1975) discussed the pleomorphic nature of Chalara and related species, but discussed this with respect to the formation of chlamydospores. Mu$ ller & Samuels (1982) noted that ‘ no species of Sporoschisma is known to be polymorphic ’ with the ‘ possible exception of S. juvenile ’. In our study we report the first association of a Chalara anamorph with S. saccardoi. Significantly, isolations made from the Sporoschisma state failed to produce the Chalara in culture while isolations from ascospores of the Melanochaeta produced both anamorph states. Although we could produce S. uniseptatum in culture from M. garethjonesii, this failed to produce a Chalara synanamorph. For now, we have no explanation for these observations. Melanochaeta hemipsila and Sporoschisma saccardoi were both recorded from hard and soft woods. Both states were, however, only recorded from the seasonal stream at km 29±2 and not from Tad Tha Phu (which flows all through the year). M. hemipsila was recorded from test blocks that had been submerged for 4–5 mo, which coincided with the end of the rainy season and the start of the cool dry season when river levels begin to fall. In contrast, S. saccardoi also appeared on wood that had only been submerged for 1 or 2 mo. Melanochaeta garethjonesii was only recorded once from km 29±2 on soft wood that had been submerged for 11 mo and would appear to be rare. In contrast, its anamorph S. uniseptatum was the most commonly encountered Sporoschisma in our study and was recorded within two months of test blocks being submerged. That there are many records of Sporoschisma compared with the few records for the Melanochaeta teleomorphs suggest that conditions necessary for the development of the Melanochaeta are not often met in the field. It is possible the appearance of the teleomorph over time is due to the increased chance of different genetic states colonizing the wood substrate. Without compatible crosses the teleomorph would not be expressed. Time will increase the chances of fertile crosses coming together if these are present in the stream to begin with. We are finding increasing numbers of homothallic ascomycetes in our studies (Hywel-Jones & Sivichai, unpubl. obs.). The circumstantial evidence of teleomorph rarity compared with anamorph prevalence, however, and the late appearance of the teleomorph compared with the anamorph, leads us to conclude that Melanochaeta could be heterothallic. This might also account for the Chalara state only appearing in cultures originating from the ascospores. We did not note germination of the Chalara state and do not know what role this might play in the life-cycle in nature. A C K N O W L E D G E M E N TS Professor E. B. Gareth Jones is thanked for the guidance that he has given to this work. Dr Kevin D. Hyde is thanked for his support and for the provision of unpublished data. This work was supported by the TRF}BIOTEC Special Programme for Biodiversity Research and Training grant BRT141022. REFERENCES Barr, M. E. (1990). Prodromus to nonlichenized, pyrenomycetous members of Class Hymenoascomycetes. Mycotaxon 39, 43–184. Courtecuisse, R., Samuels, G. J., Hoff, M., Rossman, A. Y., Cremers, G., Huhndorf, S. 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