Mycol. Res. 101 (9): 1127–1134 (1997) 1127 Printed in the United Kingdom New species of lichenicolous fungi occurring on Peltigera in Ecuador and Europe D A V I D L. H A W K S W O R T H1 A N D J O L A N T A M I AB D L I K O W S K A2 " International Mycological Institute, Bakeham Lane, Egham, Surrey TW20 9TY, U.K. # Department of Plant Ecology and Nature Protection, University of GdanU sk, Al. LegionoU w 9, 80-441 GdanU sk, Poland A study of the lichenicolous fungi occurring on species of the lichenized genus Peltigera has resulted in six new species : Libertiella curvispora, L. didymospora, L. fennica Alstrup, Polycoccum superficiale, Roselliniella peltigericola, and Zwackhiomyces kiszkianus. A key to the five known species of Libertiella is included. This paper brings the number of fungi known on this host to 87, of which 61 are not known from any other host genus, providing additional evidence for the richness of Peltigera thalli as a host for novel fungi. The possible hypotheses to explain the richness of this host genus for lichenicolous fungi are enumerated ; these are not mutually exclusive. The lichen-forming genus Peltigera (Ascomycota, Peltigerales, Peltigeraceae) was reported to be an exceptionally rich host for obligately lichenicolous fungi by Hawksworth (1980). Hawksworth provided a key to 40 species, and since that time some 37 additional fungi have been discovered on this single genus, many also proving to be new. Here we report on six further new species discovered in an examination of extensive series of collections of the genus, especially from Poland but also from other countries. Mia( dlikowska & Alstrup (1995) reported 19 species known on the genus in Poland, of which 10 were new to the country, including one newly described. A remarkable coelomycete which came to light early in our joint studies is described elsewhere (Hawksworth & Mia( dlikowska, 1997). MATERIALS AND METHODS Approximately 6000 specimens of Peltigera preserved in various collections were checked for lichenicolous fungi by J. M. ; 5000 were from Poland. Reference collections in Poland included KRA, KRAM, KRAP, KTC, LBL, LOD, PO, POZ, SLTC, TRN, UGDA, WA and WRSL (abbreviations follow Holmgren et al., 1990) and J. M. and K. Glanc’s personal collections. In addition the exceptionally rich material of this genus in H built up by Dr O. Vitikainen was also searched by J. M. in 1994. Material was located on infected thalli using a dissecting microscope, and examined with an Olympus BH-2 microscope equipped with differential interference contrast optics. Mounts were made in erythrosin in ammonia, lactophenol cotton blue, lactofuchsin, 10 % potassium hydroxide, Lugol’s solution, Melzer’s reagent, and water. Drawings were made using a drawing tube. RESULTS Libertiella curvispora D. Hawksw. & Mia( dlikowska sp. nov. (Figs 1–2) Similis Libertiellae malmedyensi Speg. & Roum. sed differt in conidiis curvatis et angustioribus, (4–)5–8¬1±5–2 µm. Typification : Poland, Bielsko-Biała distr., Carpathians, Beskid Z; ywiecki Mountains, S side of Mount Pilsko, about 12 km S to Jeles' nia, below Polana ‘ Młe( dzy Mlaki ’, alt. ca 1200 m, on P. degenii on mossy trunk of Fagus sylvatica, 10 September 1964, J. Nowak (KRAM 16363 – holotypus ; IMI 373601-isotypus). Conidiomata superficial from the first, becoming immersed only at the base in the largest conidiomata or on the lower surface of the host thallus, on the upper surface aggregated on gall-like swellings, globose but flattened around the ostiole, pale apricot or sometimes ochre, developing a deep orange ring at the apex around the incipient ostiole or becoming dark and then sometimes with no ring development, 150–420 µm diam. ; ostiole forming by disintegration of the upper tissue 1 2 Figs 1–2. Libertiella curvispora (holotype). Fig. 1. A, Conidiophores and conidiogenous cells. Fig. 2. Conidia. Bar, 10 µm. New lichenicolous fungi on Peltigera 1128 6 7 3 Figs 6–7. Libertiella didymospora (holotype). Fig. 6. Conidiophores and conidiogenous cells. Fig. 7. Conidia. Bar, 10 µm. may not be rare and it clearly should be sought at least in adjoining countries. 4 5 Figs 3–5. Libertiella didymospora (holotype). Fig. 3. Pycnidia on the host thallus. Fig. 4. Vertical section of pycnidial wall and conidiogenous cells. Fig. 5. Conidia. Scale bars, 0±5 mm (Fig. 3) ; 10 µm (Figs 4, 5). inside a preformed ring, visible from above as a whitish spot 40–60 µm diam. ; conidiomatal wall 12–18 µm thick, translucent, composed of very thick-walled pseudoparenchymatous cells, cells of the inner layers radially compressed and elongated, and those of the outer 1–3 layers 7±5–11 µm diam., interspersed with orange granules. Conidiophores lining the inner wall of the pycnidial cavity, erect, cylindrical, richly branched, 2–8¬3–3±5 µm. Conidiogenous cells arising terminally and laterally on the conidiophores, cylindrical, periclinally thickened, collarette short, 5–12¬2–3±5 µm. Conidia enteroblastic, simple, hyaline, narrowly ellipsoid and consistently somewhat curved, base sometimes slightly truncated, smooth, adhering together, (4–)5–8¬1±5–2 µm. Ecology : On the upper and especially the lower surfaces of Peltigera thalli of the following species : P. canina, P. degenii, P. ponojensis, and P. praetextata. No damage is seen in most of the infected specimens, and the fungus generally appears to be commensalistic. However, in some cases the conidiomata are associated with gall-like deformations. Distribution : Poland ; known for eight collections, mainly from mountainous areas in the southern part of the country. The number of collections reported here suggests that the species Observations : Only two species of Libertiella Speg. & Roum. have previously been formally recognized : L. malmedyensis Speg. & Roum. on Peltigera species, with ellipsoid to obovoid conidia (5–)6–8¬(2–)3–4 µm (Hawksworth, 1981) ; and L. leprariae Etayo & Diederich on Lepraria lobificans, also with ellipsoid to obovoid conidia but only 1±5–3¬1–1±5 µm (Etayo & Diederich, 1995). Libertiella didymospora, newly described below, has (0–)1-septate conidia which are not curved and 7–10¬2–2±5 µm. In addition to the conidial characteristics, L. curvispora has much larger cells in the conidiomatal wall than L. malmedyensis. A key to the five species now known in the genus is presented below. Additional specimens : Poland, Carpathian Mountains, Tatra Mountains, Dolina Kos' cieliska, Polana Smytnia, alt. ca 1110 m, on Peltigera canina, 19 August 1983, J. Kiszka (KRAP) ; Carpathian Mountains, Beskid S; la: ski Mountains, Wisła valley, near the road to Czarne, alt. ca 510 m, on P. canina, 15 June 1963, J. Kiszka (KRAP) ; Pieniny National Park, Polana Flaki, on P. ponojensis, 21 June 1988, J. Kiszka (KRAP) ; Beskid ZJ ywiecki Mountains, Glinka near Ujsoły, alt. ca 600 m, on P. canina on the ground, 14 August 1964, J. Nowak (KRAM 14047) ; Bieszczady Mountains, Puszcza Bukowa, N slope of Dział, alt. ca 750 m, on P. praetextata on mossy trunk of Fagus sylvatica, 9 May 1955, K. Glanc (UGDA) ; Lublin dstr., Krzczono! w, on P. praetextata on bark of Quercus sp., 26 February 1955, K. Tatarkiewicz (LBL 893) ; Puszcza Knyszyn! ska, Barania Woda, between Straz0 e and Dworzyska, on P. praetextata on bark of Populus tremula, 10 August 1962, K. Glanc (UGDA). Libertiella didymospora D. Hawksw. & Mia( dlikowska sp. nov. (Figs 3–7) Similis Libertiellae malmedyensi sed differt in conidiis (0–)1-septatis, longioribus et angustioribus, 7–10¬2–2±5 µm. Typification : Poland, Wigierski National Park, Wigry Lake, on Peltigera rufescens on ground in pine forest at lakeside, 11 October 1984, J. Kiszka (KRAP – holotypus ; IMI 373604). Conidiomata superficial from the first, becoming immersed at the base, confined to the lower surface, scattered or forming loosely aggregated groups, not associated with gall-like swellings, globose but flattened around the ostiole, whitish to pale apricot or sometimes ochre, developing a bright orange ring at the apex around the incipient ostiole, 240–480 µm D. L. Hawksworth and J. Mia( dlikowska 8 1129 9 Figs 8–9. Libertiella fennica (holotype). Fig. 8. Pycnidium wall, conidiophores and conidiogenous cells. Fig. 9. Conidia. Bar, 10 µm. diam. ; ostiole forming by disintegration of the upper tissue inside a preformed ring, visible from above as a whitish spot to 120 µm diam. ; conidiomatal wall to ca 25 µm thick, translucent, composed of thick-walled pseudoparenchymatous cells, cells of the inner layers radially compressed and elongated, and those of the outer layers 3±5–4±5 µm diam. Conidiophores lining the inner wall of the pycnidial cavity, erect, cylindrical, sparsely branched, 6–12¬2±5–3 µm. Conidiogenous cells mainly arising terminally and more rarely laterally on the conidiophores, cylindrical, periclinally thickened, collarette short, sometimes proliferating, 6–14¬ 1±5–3±5 µm. Conidia enteroblastic, (0–)1-septate, the septum often not median, not constricted at the septum, hyaline, narrowly ellipsoid, base sometimes slightly truncated, smooth, adhering together, 7–10¬2–2±5 µm. Conidiomata superficial, arising singly, not aggregated into groups, globose, white when young, gradually becoming brownish and finally almost black with age, a darker ring not formed at the apex, to 250 µm diam. ; conidiomatal wall formed of 3–5 layers of translucent hyaline cells, cells of the outer layers 2–3 µm thick. Conidiophores lining the inner wall of the pycnidial cavity, erect, cylindrical, irregularly branched, 2–3 µm wide. Conidiogenous cells cylindrical, periclinally thickened, collarette not evident, to 8¬3 µm. Conidia enteroblastic, simple, hyaline, ovoid or pyriform to subglobose, base slightly truncated, smooth, abundant, 3–3±5¬2±5–3 µm. Ecology : This species, which occurs on the upper surface of thalli of Peltigera neckeri and P. rufescens, was first thought to be lichenized as it was associated with a thin layer of goniocysts. More critical examination revealed that the pycnidia of Libertiella fennica originate in depressions of the thallus lobes which can be subsequently covered by goniocysts. The species appears to be commensalistic. Distribution : Finland and Norway. Observations : Distinguished from the other four species of the genus by the ovoid or pyriform to subglobose shape and small size of the conidia. In addition, instead of a dark ring always forming around the incipient ostiole, in Libertiella fennica the colour change can start in any part of the pycnidium and then spread over the entire surface. Ecology : Developing only on the underside of Peltigera rufescens, and not associated with any damage, discolouration or galls ; evidently commensalistic. Additional specimen : Norway, Granvin in Hardanger, on P. rufescens, May 1902, H. Havaas (C). Distribution : Poland ; known from two collections. Polycoccum superficiale D. Hawksw. & Mia( dlikowska sp. nov. (Figs 10–17) Observations : Distinguished from the other four species of the genus by the shape, size and septation of the conidia (see above). Additional specimen : Poland, Kotło! w near Złoczo! w, pine forest ‘ Ostro' wek ’, on P. rufescens in border of forest, 28 July 1937, J. Ma\ dalski (KRAM 41582). Libertiella fennica Alstrup sp. nov. (Figs 8–9) Similis Libertiellae malmedyensi sed differt in pycnidiis albis dum juvenibus et conidiis ovoideis vel pyriformis ad subglobosis, 3–3±5¬2±5–3 µm. Typification : Finland, Etelae-Haeme, Padasjoki, Kasiniemi, on Peltigera neckeri, 17 May 1987, V. Haikonen 8226 (H – holotypus). Similis Polycocco peltigero (Fuckel) Ve) zda, sed differt in peritheciis superficialibus, cum muris e cellulis noncompressis, et ascosporis 15±5–19¬6–6±5 µm. Typification : Russia, Vyczegda, prope opp. Ssolvyczegodsk, on Peltigera malacea ‘ ad terram in sylva pinosa juvenali ’, 1928, V. J. Mazjukevicz [ex-herb. UGDA] (IMI 371825 – holotypus). Ascomata perithecia, superficial, dispersed, not aggregated into groups, dark brown to black, subglobose below but becoming applanate above, 150–200 µm diam. ; wall 31–38 µm thick, composed of pseudoparenchymatous cells ; cells black, subglobose, not radially flattened, 7±5–9¬6–7±5 µm ; ostiole a minute papilla projecting from the centre of the applanate upper part, to ca 25 µm diam., periphyses well-developed in the ostiolar canal, septate, 1–2±5 µm wide. Hamathecium of cellular pseudoparaphyses, well-developed, branched, repeat- Key to the known species of Libertiella 1. Conidia all non-septate . . . . . . Conidia (0–)1-septate, narrowly ellipsoid, 7–10¬2–2±5 µm 2(1) Conidia ellipsoid to obovoid, pyriform or subglobose Conidia curved, (4–)5–8¬1±5–2 µm . . . 3(2) Conidia not exceeding 3±5 µm in length . . . Conidia (5–)6–8¬(2–)3–4 µm . . . . . 4(3) Conidia 3–3±5¬2±5–3 µm . . . . . Conidia 1±5–3¬1–1±5 µm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 . L. didymospora . . . 3 . L. curvispora . . . 4 . L. malmedyensis . . L. fennica . L. leprariae New lichenicolous fungi on Peltigera 1130 18 10 20 19 Figs 18–20. Roselliniella peltigericola (holotype). Fig. 18. Ascus with ascospores. Fig. 19. Hamathecial tissue. Fig. 20. Ascospores. Bar, 10 µm. 11 13 12 Figs 10–13. Polycoccum superficiale (holotype). Fig. 10. Perithecia on the host thallus. Fig. 11. Vertical section of perithecial wall. Fig. 12. Hamathecium with anastomosing pseudoparaphyses. Fig. 13. Asci with ascospores. Scale bars, 0±5 mm (Fig. 10) ; 10 µm (Figs 11–13). 15 14 edly septate, 1–2±5(–3) µm wide ; hymenial gelatin not reacting with Lugol’s solution (after pre-treatment with 10 % potassium hydroxide) or Melzer’s reagent. Asci elongate–clavate, bitunicate in structure, slightly thickened at the apex with a shallow internal apical beak, 45–58¬13±5–16 µm, 8-spored. Ascospores distichously arranged in the ascus, elongate– ellipsoid, somewhat pointed at the apices, 1-septate, each cell with a distinct guttule, cells equal in size or the upper slightly larger, the septum without a distinct central pore, most slightly constricted at the septum, brown, smooth-walled, lacking a distinct gelatinous sheath, 15±5–19¬6–6±5 µm. Conidiomata intermixed with the ascomata on the host thallus, superficial, subglobose, dark brown to black. Conidiophores absent. Conidiogenous cells obpyriform, arising immediately inside the conidioma wall, ca 6–7 µm diam. Conidia enteroblastic, ellipsoid to oblong, simple, colourless, 4±5–7±5¬2±5–4 µm. Ecology : The affected areas of the thallus are somewhat darker in colour than the main part but this may be fortuitous as the ascomata do not occur throughout the deeper coloured areas. As there is no evidence of gall formation or necrosis, the fungus appears to be either commensalistic or perhaps saprobic. Distribution : Known from two collections, both on Peltigera malacea in Europe : the holotype from Russia and a doubtfully localized specimen that is most probably from Germany (see below). 16 17 Figs 14–17. Polycoccum superficiale (holotype). Fig. 14. Ascus with ascospores. Fig. 15. Hamathecial tissue of pseudoparaphyses. Fig. 16. Ascospores. Fig. 17. Conidia. Bar, 10 µm. Observations : The generic placement of this fungus remains uncertain. The ascospores recall those of Polycoccum Saut. ex Ko$ rb. in being almost equal-celled and 1-septate, but are paler brown and not ornamented. More significantly, the ascomata are entirely superficial rather than immersed or erumpent, and the cells in the ascomatal wall are not radially compressed. In addition the fungus does not form galls on the host. We considered a placement in Pyrenidium Nyl., but in that genus the ascospores are multi-septate, with central pores D. L. Hawksworth and J. Mia( dlikowska 21 1131 22 Figs 21–22. Zwackhiomyces kiszkianus (holotype). Fig. 21. Perithecia on the host thallus. Fig. 22. Vertical section of perithecium. Scale bars, 0±5 mm (Fig. 21) ; 100 µm (Fig. 22). in the septa, much larger, and generally darker except for paler end cells. Two species of Polycoccum have previously been recognized on Peltigera : P. crassum Ve) zda with coarsely ornamented ascospores (25–)30–32(–36) µm in length ; and P. peltigerae (Fuckel) Ve) zda with smooth ascospores (12–)13±5–16 µm in length (Hawksworth & Diederich, 1988). P. peltigerae is reported as producing a Cyclothyrium-like anamorph with pale brownish conidia which in culture were stated to measure 4±3–8±2¬2±8–4±7 µm (van der Aa, 1989). In the P. peltigerae anamorph the conidogenous cells occur in cavities of a stromatic conidioma rather than singly, but the conidiogenous cells are not dissimilar from those of the new species. The connection of the putative anamorph described for P. superficiale above requires verification by culture from single ascospores when fresh collections are found. Additional specimen : [Germany ?], ‘ In ericet. mit musc. pr. Sondershausen ’, on Peltigera malacea, [pre-1904], Ekardt, ex-herb. B. Stein (WRSL). Roselliniella peltigericola D. Hawksw. & Mia( dlikowksa sp. nov. (Figs 18–20) Similis Roselliniellae coccocarpiae (Pat.) Matzer & R. Sant., sed differt in ascosporis subglobosis ad ellipsoideis et apicibus gelatinosis desunt, 11–20±5¬6–7±5 µm. Typification : Ecuador, Azuay, Gualaceo-Limo! n road, alt. 2600 m, on Peltigera spuriella on mossy rocks at road side, 11 July 1983, L. Arvidsson & A. Arvidsson (H – holotypus). Ascomata perithecia, superficial, aggregated into dark brown to black groups, obpyriform, to 360 µm diam. ; wall 32–37 µm thick, composed of 5–8 rows of dark brown to black, pseudoparenchymatous cells ; cells polyhedral, rounded in the outer layers and radially compressed in the inner, thick-walled, the lumina often occluded, 8–9±5¬2–3 µm ; ostiole welldeveloped, ca 45 µm wide, with periphyses abundantly developed in the ostiolar canal, periphyses unbranched, mainly 1±5–2 µm wide. Hamathecium of paraphyses, sparse, simple or rarely branched towards the apices, repeatedly septate, cells very uneven in thickness, 1–3 µm. Asci cylindrical, walls even in thickness, unitunicate in structure, lacking any differentiated apical apparatus, 77¬8 µm, 8-spored. Ascospores uniseriately arranged in the ascus, subglobose to ellipsoid, brown, thick-walled, simple, with 1–2 conspicuous guttules occupying almost all the central part of the ascospore, lacking apical extensions to the gelatinous sheath, 11–20±5¬ 6–7±5 µm, length : breadth ratio 1±6–2. Ecology : The affected portion of the host thallus is somewhat decolourized, but there is no obvious necrosis and no galls are produced. Further material is needed to ascertain if the species is a commensal or a mild parasite. Distribution : Ecuador ; known only from the original collection. Observations : This new species is most similar to Roselliniella coccocarpiae (Pat.) Matzer & R. Sant., known on Degelia (Lecanorales, Pannariaceae) species from Chile and New Zealand, but that species has more elongate ascospores (length : breadth ratio 1±5) with a distinct gelatinous apical cap when inside the ascus (Matzer & Hafellner, 1990). Zwackhiomyces kiszkianus D. Hawksw. & Mia( dlikowska sp. nov. (Figs 21–25) Similis Zwackhiomyci sphinctrinoidei (Zwackh) Grube & Hafellner sed differt in ascosporis majoribus, 19±5–25±5¬8±5–13 µm. Typification : Germany, ‘ an rivum Jensi Kirgenrbrau ’ [? script unclear], 6 April 1869, [G. W. KoX rber 10.38b] (KRAM 010692 – holotypus). New lichenicolous fungi on Peltigera 1132 fungi after World War II, and who kindly made his collections available to J. M. for study. 23 25 24 Observations : Only one species of Zwackhiomyces Grube & Hafellner has previously been reported as occurring on species of Peltigera, Zwackhiomyces peltigerae Mia( dlikowska & Alstrup, which differs in the smaller ascospores which measure 13–16¬3±5–6 µm (Mia( dlikowska & Alstrup, 1995). Ascospores of the new species are most similar to those of Z. sphinctrinoides (Zwackh) Grube & Hafellner in length, but the latter are generally shorter and consistently narrower, measuring 16–23¬4±5–8 µm (Grube & Hafellner, 1990). Further Z. sphinctrinoides occurs on a wide range of crustose lichenized genera belonging to Lecanorales and Teloschistales. DISCUSSION Figs 23–25. Zwackhiomyces kiszkianus (holotype). Fig. 23. Ascus with ascospores. Fig. 24. Hamathecial tissue of pseudoparaphyses. Fig. 25. Ascospores. Bar, 10 µm. Ascomata perithecia, scattered, not associated with any necrotic patches or galls, immersed in the host thallus, exposed only at the ostiole, dark brown to black, 180–240 µm diam. ; wall composed of pseudoparenchymatous cells, to 20 µm wide at the base and increasing to 30 µm wide in the ostiolar region, textura angularis, individual cells subglobose to polyhedral, thick-walled, dark brown, not strongly compressed radially, 8±5–9±5¬6±5–8±5 µm ; ostiolar region somewhat constricted, ostiole to 65 µm wide, periphyses lining the ostiolar canal ; periphyses simple, 1±5–2±5 µm thick. Hamathecium of cellular pseudoparaphyses, sparse, not always evident in squash preparations, branched and anastomosing, 1–2 µm thick ; hymenial gel unchanged in Lugol’s solution (after pretreatment with 10 % potassium hydroxide) or Melzer’s reagent. Asci elongate-clavate to almost subcylindrical, bitunicate in structure, apex strongly thickened internally with an internal apical beak, discharged asci not seen, 90–105¬14–15±5 µm, 6(–8) spored. Ascospores overlapping in the asci, broadly ellipsoid to somewhat soleiform, 1-septate, constricted at the septum, with a refractive spot at the junction of the septum and wall, cells equal in size or the basal cell smaller, the upper cell somewhat swollen with a rounded apex and the lower somewhat narrowed at the tip, surrounded by a perispore with a granular internal ornamentation, 19±5–25±5¬ 8±5–13 µm. Ecology : The fungus does not cause any obvious damage to the affected portions of the thallus of Peltigera canina, which retains its normal colour. The species therefore appears to be commensalistic rather than parasitic. Distribution : Germany ; known only from the type collection. Etymology : This species is named in honour of Professor Jozef Kiszka of the Educational University in Krakow, one of the first Polish scientists to become interested in lichenicolous Inclusive of the species described in this contribution, and five further names awaiting description, 87 lichenicolous fungi belonging to 57 genera are now known to occur on Peltigera thalli, 61 of which only occur on that host genus, three probably being anamorphs of others also listed (Table 1). The remarkable number of fungi which occur only on Peltigera, and others also on different genera in the Peltigeraceae, led Hawksworth (1982) to suggest that this particular group of lichens was especially ancient, an hypothesis supported by ascomatal ontogeny, ascus structure, and the wide geographical distribution of many species. Independently, Eriksson (1981) concluded that Peltigerales could be of particular antiquity because of the ascus structure. In the Venn diagram constructed by Dick & Hawksworth (1985), the order extended from a basal position. Galloway (1991) considered that the great chemical diversity in the order also supported this hypothesis. Interestingly, Pseudocyphellaria, also in Peltigerales but belonging to Lobariaceae, is proving an exceptional host of novel fungi. Kondratyuk & Galloway (1995) reported 51 species of lichenicolous fungi from that host. In particular they also noted that chemical differences in the hosts appeared to be correlated with the pattern of species growing on them within this one genus. Molecular work was carried out for the first time on members of the Peltigerales by Eriksson & Strand (1995) who examined 18S rDNA sequences of Nephroma arcticum, Peltigera neopolydactyla and Solorina crocea. These three species were found to form a monophyletic clade and to be more closely related to Lecanorales than to Leotiales or Pezizales. While evidence for some links was not robust, the order did not occupy as low a position as might have been suggested on other grounds. This means that factors other than antiquity may contribute to the richness of Peltigerales as hosts for lichenicolous fungi. Two particular hypotheses may merit consideration : (1) the triterpenoid secondary chemicals present in thalli in many Peltigerales are more easily adapted to by other fungi in comparison with lichens in which orcinol derivatives predominate ; and (2) large foliose thalli, in many cases with tomentose surfaces and tending to live in moist habitats, may provide a particularly favourable niche for the development of D. L. Hawksworth and J. Mia( dlikowska Table 1. Summary of the lichenicolous fungi recorded on Peltigera species 1. *Acanthonitschkea peltigericola (Alstrup & Olech) O. E. Erikss. & R. Sant. 2. Arthonia fuscopurpurea (Tul.) R. Sant. 3. *Arthonia peltigerea Th. Fr. 4. *Arthonia peltigerina (Almq.) H. Olivier 5. Arthonia pelveti (Hepp) Almq. 6. *Bacidia killiasii (Hepp) D. Hawksw. 7. Barya lichenophila Ferd. & Winge 8. *Capronia peltigerae (Fuckel) D. Hawksw. 9. Cercidospora lichenicola (Zopf) Hafellner 10. *Corticifraga fuckelii (Rehm) D. Hawksw. & R. Sant. 11. *Corticifraga peltigerae (Fuckel) D. Hawksw. & R. Sant. 12. Dacampia engeliana (Saut.) A. Massal. 13. *Dacampia rufescentis (Vouaux) D. Hawksw. 14. Dinemasporium strigosum (Pers.) Sacc. (P) 15. *Diplodina peltigerae Vouaux 16. Fayodia arctica Gulden 17. *Fayodia leucophylla (Gillet) M. Lange & Sivertsen 18. Fayodia xerophila Luthi & Ro$ llin 19. *Fusarium peltigerae Westend. 20. *Graphium aphthosae Alstrup & D. Hawksw. 21. *Hawksworthiana peltigericola (D. Hawksw.) U. Braun 22. Hemigrapha astericus (Mu$ ll. Arg.) R. Sant. ex D. Hawksw. 23. *Hobsonia santessonii Lowen & D. Hawksw. 24. *Hystrix peltigericola Alstrup & Olech 25. *Illosporium carneum Fr." 26. *Karsteniomyces peltigerae (P. Karst.) D. Hawksw.# 27. *Karsteniomyces tuberculosus Alstrup & D. Hawksw.$ 28. *Lasiosphaeriopsis salisburyi D. Hawksw. & Sivane. 29. *Leptosphaeria clarkii D. Hawksw. 30. *Leptosphaerulina peltigerae (Fuckel) Riedl 31. *Libertiella curvispora D. Hawksw. & Mia( dlikowska 32. *Libertiella didymospora D. Hawksw. & Mia( dlikowska 33. *Libertiella fennica Alstrup 34. *Libertiella malmedyensis Speg. & Roum. 35. *Lichenopeltella peltigericola (D. Hawksw.) R. Sant. 36. *Lichenopeltella santessonii (P. M. Kirk & Spooner) R. Sant. 37. *Nanostictis peltigerae M. S. Christ. 38. Nectria lecanodes Ces. 39. *Neolamya peltigerae (Mont.) Theiss. & Syd. 40. *Norrlinia peltigericola (Nyl.) Theiss. & Syd. 41. *Omphalina cupulatoides P. D. Orton 42. *Orbilia peltigerae (Fuckel) Sacc. 43. *Paranectria superba D. Hawksw. 44. *Pezizella epithallina (W. Phillips & Plowr.) Sacc. 45. *Phaeospora peltigericola D. Hawksw. 46. *Phoma epiparmelia Vouaux 47. *Phoma peltigerae (P. Karst.) D. Hawksw. 48. Phyllactina guttata (Wallr.) Le! v. (P) 49. Polyblastia gelatinosa (Ach.) Th. Fr. (L) 50. *Polycoccum crassum Ve) zda 51. *Polycoccum peltigerae (Fuckel) Ve) zda 52. *Polycoccum superficiale D. Hawksw. & Mia( dlikowska 53. *Polydesmia lichenis Huhtinen & R. Sant. 54. *Pronectria erythrinella (Nyl.) Lowen 55. Pronectria ornamentata (D. Hawksw.) Lowen 56. *Pronectria robergei (Mont. & Desm.) Lowen 57. *Pronectria tenuispora (D. Hawksw.) Lowen 58. Protothelenella crocea (Bagl. & Carestia) Hafellner 59. Protothelenella sphinctrinoides (Nyl.) H. Mayrhofer & Poelt (L) 60. Pyrenidium actinellum Nyl. 61. *Refractohilum peltigerae (Keissl.) D. Hawksw. 62. Rhagadostoma lichenicola (de Not.) Keissl. 63. Rinodina egedeana (Linds.) Alstrup & D. Hawksw. 64. Rinodina olivaceobrunnea C. W. Dodge & G. E. Baker 65. Rinodina turfacea (Wahlenb.) Ko$ rb. 66. Sarcosagium campestre (Fr.) Poetsch & Schied. (L) 67. *Scutula aggregata (Bagl. & Carestia) Rehm 68. *Scutula miliaris (Wallr.) Trevis. 1133 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. *Skyttella mulleri (H. Wiley) D. Hawksw. & R. Sant. Steinia geophana (Nyl.) B. Stein (?L) *Stigmidium peltideae (Vain.) R. Sant. *Stigmidium pseudopeltideae Cl. Roux & Triebel Thelocarpon epibolum Nyl. (incl. var. epithallinum (Leight. ex Nyl.) G. Salisb.) (?L) *Trichoconis lichenicola D. Hawksw. *Trichosphaeria lichenum P. Karst. & Har. *Vagnia cirriformia D. Hawksw. & Mia( dlikowska Vezdaea aestivalis (Ohlert) Tscherm.-Woess & Poelt (L) Vezdaea retigera Poelt & Do$ bbeler *Wentiomyces peltigericola D. Hawksw. *Zwackhiomyces kiszkianus D. Hawksw. & Mia( dlikowska *Zwackhiomyces peltigerae Mia( dlikowska & Alstrup Zwackhiomyces sphinctrinoides (Zwackh) Grube & Hafellner * Species only known on species of Peltigera. L, lichen-forming ; other fortuitously lichenicolous species encountered are omitted (e.g. Bacidia bagliettoana (A. Massal.) De Not., Bacidina delicata (Larbal. ex Leight.) Coppins, B. chloroticula (Nyl.) Ve) zda & Poelt, Micarea peliocarpa (Anzi) Coppins & R. Sant., Protothelenella sphinctrinoidella (Nyl.) H. Mayrhofer & Poelt, Toninia lobulata (Sommerf.) Lynge, Vezdaea rheocarpa (Poelt & Do$ bbeler). Myxomycetes can also be found (e.g. Didymium squamulosum (Alb. & Schwein.) Fr., Lamproderma scintillans (Berk. & Broome) Morgan). P, occurring also on plants. Probable anamorphs : Three species are probable anamorphs of others listed on circumstantial evidence but yet to be proved by single ascospore cultures : "Pronectria robergei, #Scutula miliaris, and $S. aggregata. Sources used : Alstrup & Hawksworth (1990), Hawksworth (1980), Index of Fungi, Santesson (1993) and unpublished records. Names treated as of doubtful application by Hawksworth (1980) are omitted. Note : In addition to the species enumerated here, we are aware of a further five species new to science occurring on the genus awaiting formal descriptions. novel fungi. Additional data need to be accumulated to test the relative significance of the three possible hypotheses as they are not mutually exclusive. We are indebted to the curators of collections cited under Materials and Methods for the loan of material. Dr Vagn Alstrup (Botanical Institute, University of Copenhagen) kindly made available to us his as yet unpublished key to the lichenicolous fungi known on Peltigera, permitted us to incorporate his account of Libertiella fennica here, and also made helpful comments on a draft of this manuscript. Drs B. J. Coppins (Royal Botanic Gardens, Edinburgh) and B. Ing (Chester College) kindly assisted in identifying some fortuitously present lichens and slime moulds, and Ms G. Godwin (International Mycological Institute) provided photographic assistance. This work was carried out at IMI with the support of a CEC DG XII Tempus Individual Mobility Grant (No. IMG-95-PL-1056) and Project No. 6 PO4C 077 10 of the Polish Committee of Scientific Research (KBN) to J. M. REFERENCES van der Aa, H. A. (1989). Polycoccum peltigerae and Didymosphaeria arxii sp. nov. and their anamorphs. Studies in Mycology 31, 15–22. Alstrup, V. & Hawksworth, D. L. (1990). The lichenicolous fungi of Greenland. 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