Arrhenia peltigerina (Peck) Redhead, Lutzoni, Moncalvo & Vilgalys is a lichenicolous homobasidiomycete showing agaricoid-omphalinoid basidiomes with gilled hymenophores, smooth basidiospores and lacking cystidia. It grows on dead, necrotized thalli of species of the foliose lichen genus Peltigera Willd. Lichenicolous species within the homobasidiomycetes are unusual and scarcely known, but some new species have recently been reported (Diederich & Lawrey Reference Diederich and Lawrey2007). Current phylogenetic studies incorporate the genus Arrhenia Fr. into the family Hygrophoraceae within Agaricales and, it has been suggested that it is the ancestor of the lichenized genus Dictyonema C. Agardh ex Kunth, which shows stereoid-corticioid basidiomes with smooth hymenophore (Lawrey et al. Reference Lawrey, Lücking, Sipman, Chaves, Redhead, Bungartz, Sikaroodi and Gillevet2009).
Species of another agaric genus Gamundia Raithelh. have also been suggested to be lichenicolous on Peltigera in northern Europe and North America (e.g. Bigelow Reference Bigelow1985, sub Stachyomphalina H. E. Bigelow; Antonín & Noordeloos Reference Antonín and Noordeloos2004), but no clear nutritional and ecological relationships have been established. Gamundia striatula (Khüner) Raithelh. was reported growing “… on or near …” Peltigera [Bigelow Reference Bigelow1979: 42, as Stachyomphalina striatula (Kühner) Bigelow; Alstrup & Hawksworth Reference Alstrup and Hawksworth1990, as Fayodia striatula (Kühner) Singer]. Gamundia leucophylla (Fr.) H. E. Bigelow was not seen to grow on Peltigera in the field but “… On closer examination of the drier material, however, small pieces of ± moribund Peltigera cf. leucophlebia were found …” (Gulden Reference Gulden1987: 55, as Fayodia arctica Gulden; see also Santesson Reference Santesson1993: 150, comments on Omphalina cupulatoides). In spite of these ambiguous nutritional and ecological relationships, microscopic features of the species included in Gamundia include rough spores (Bigelow Reference Bigelow1983) and conspicuous cheilo- and pleurocystidia. Therefore, they are quite different from A. peltigerina, which has smooth basidiospores and lacks cheilo-, caulo- and pleurocystidia.
Arrhenia peltigerina is an uncommon but widely distributed species in Europe and North America (cf. Garnier-Delcourt Reference Garnier-Delcourt2008). A taxonomic discussion and a detailed description of this species were carried out by Collin & Lauron (Reference Collin and Lauron1994, sub Omphalina peltigerina). Moreover, Omphalina cupulatoides was also described from the United Kingdom growing on necrotized areas of a thallus of the foliose lichen Peltigera polydactylon (Orton Reference Orton1977). This taxon has been successively synonymized to A. peltigerina by several authors (Collin & Lauron Reference Collin and Lauron1994; Vila Reference Vila2002; Garnier-Delcourt Reference Garnier-Delcourt2008; Elborne Reference Elborne, Knudsen and Vesterholt2008), but no type material was examined in any of these studies.
Examination of the type material of Cantharellus peltigerae Velen. revealed that it is conspecific with A. peltigerina. A more detailed discussion on the identity of C. peltigerae has recently been carried out by Hawksworth et al. (Reference Hawksworth, Rico, Barrasa and Kokourkova2009).
The type material of Agaricus peltigerinus Peck cited in the protologue (Peck Reference Peck1878), is confusing since two collections from different localities, Oneida and North Greenbush (New York State) were cited; a problem that had already been noted by John Haines (1981, ex-curator of NYS) in an annotation included with the type. Bigelow (Reference Bigelow1985: 400) in the ‘material examined’ section cited as “holotype” the Oneida specimen. This effectively lectotypified the name, but using an incorrect term that we have to correct here, according to Art. 9.8 of the ICBN (McNeill et al. Reference McNeill, Barrie, Burdet, Demoulin, Hawksworth, Marhold, Nicolson, Prado, Silva, Skog, Wiersema and Turland2006).
In this note we also illustrate and compare morphological features of the type material of Agaricus peltigerinus Peck and Omphalina cupulatoides P. D. Orton to solve the taxonomic and nomenclatural confusions above mentioned.
The type material of Agaricus peltigerinus Peck, Cantharellus peltigerae Velen. and O. cupulatoides and a number of other collections of O. cupulatoides have been examined. Additional fresh material of A. peltigerina collected by the authors in mountainous areas of central Spain has also been included in this study for comparison of its macro- and microscopic features.
Colours of the basidiomata were determined by reference to Munsell (Reference Munsell1994). For basidiospore Q method (length:breath ratio), cf. Heinemann & Rammeloo (Reference Heinemann and Rammeloo1985).
Arrhenia peltigerina (Peck) Redhead, Lutzoni, Moncalvo & Vilgalys
Mycotaxon 83: 48 (2002).—Agaricus peltigerinus Peck, Annual Rep. New York State Mus. Nat. Hist. 30: 38 (1878) [basionym, as “Agaricus (Clitocybe) peltigerinus”]. —Clitocybe peltigerina (Peck) Sacc., Syll. Fung. 5: 184 (1887).—Clitocybe peltigerina (Peck) Peck, New York State Mus. Bull. 157: 87 (1912) [superfl. comb.].—Omphalina peltigerina (Peck) P. Collin, in P. Collin & A. Lauron, Bull. Soc. Mycol. France 110: 11 (1994); type: USA, “New York State, Oneida, on Peltigera sp., H. A. Warne” (NYS 2308—lectotype!).
Omphalina cupulatoides P. D. Orton, Kew Bull. 31: 712 (1977); type: United Kingdom, Scotland, “Perthshire, Rannoch, Dall, Sawmill Site, on Peltigera sp., 29 September 1971, Orton 4192” (E 157979—holotype!).
Cantharellus peltigerae Velen., Vĕda Přírodní 1: 270 (1920); type: Czech Republic, Prague, Chuchle, on old thalli of Peltigera sp., April 1910, O. Reisner (PRC 336[a] [parte cum Peltigera]—lectotype!; cf. Hawskworth et al. 2009).
Selected descriptions and iconography: Orton (Reference Orton1977: 712 descr.; as O. cupulatoides); Bigelow (Reference Bigelow1985: 400 descr., Fig. 157 icon.); Collin & Lauron (Reference Collin and Lauron1994: 12 descr., plate 280 icon.; as Omphalina peltigerina); Vila (Reference Vila2002: 211 descr., 212-213 icon., (fig. 1 and plate); as O. peltigerina); Garnier-Delcourt (Reference Garnier-Delcourt2008: 5 descr., 4-5 icon. (figs 1 and 3)); Elborne (Reference Elborne, Knudsen and Vesterholt2008: 229 descr., 231 icon. (fig. 231a)).
Agaricus peltigerinus Peck (lectotype, NYS 2308). A, hyphae of the stipe; B, hyphae of the pileus; C, hyphae of the lamellar trama; D, basidia and basidiole; E, basidiospores. Scale = 10 μm.
Omphalina cupulatoides P. D. Orton (holotype, E 157979). A, hyphae of the stipe; B, hyphae of the pileus; C, terminal hyphae of the lamellar trama; D, basidia and basidiole; E, basidiospores. Scale = 10 μm.
Arrhenia peltigerina (AH 32777). A, fruit body on Peltigera thallus; B, hyphae of the pileus (DIC); C, clamps (DIC); D, basidia (DIC); E, basidiospores (DIC). Scales: A = 2 mm; B–E = 10 μm.
Mycelium growing in moribund, necrotized thalli of Peltigera sp.
Basidiomata omphalinoid, lamellated, 0·8–30 mm tall, mostly developed from the lower surface of the lichen thallus. Pileus thin, 5–20 mm wide, convex to nearly plane or umbilicate, with undulate and striate margin, glabrous to pubescent, brown to dark brown (7·5YR 2·5/3 to 5/6) or yellowish red (5YR 5/8 to 6/8), light brown to brown when dry (7·5YR 5/3, 6/3 to 6/4). Lamellae decurrent, distant, 8–12(–15) mm long, thick, forked near cap, somewhat veined, pinkish white to pink, ± concolorous with stipe, with darker edge. Stipe 8–20 × 0·8–3 mm, cylindrical with slightly thicker base, pinkish white to pink (5YR 8/2 to 8/3, 7·5YR 8/2 to 8/3), pruinose to pubescent, floccose at the base. Flesh concolorous, whitish when dry. Smell none. Basidia (25–)27–40 × 5–8(–9) μm, subclaviform, 4-spored, sterigmata 3–8 μm long. Basidioles 25–35 × 4–8 μm, subclaviform to claviform. Basidiospores 6–9(–10) × (3·5–)4–6(–6·5) μm (n = 150), Q = 1·33–1·61–1·89, ellipsoidal to elongate, with prominent apiculus, smooth, non-amyloid. Pileipellis a cutis of cylindrical hyphae with ascending free ends, (2·5–)3–10 μm wide, with intracellular and slightly extracellular encrusted pigment. Stipitipellis a cutis of cylindrical, slightly swollen hyphae, 6–14 μm wide. Lamellar trama irregular, with branched hyphae, (1·5–)2·5–6 μm wide, with slightly encrusted pigment. All tissues with clamp connections.
Notes. The lectotype of Agaricus peltigerinus Peck is old and has deteriorated. There are only a few sparse basidiomata fragments (stipe and pileus), a segment of stipe attached to a portion of Peltigera thallus, and indeterminate portions. Several different microscopic observations of these pieces of lectotype revealed some of the most distinctive micromorphological features known from fresher specimens of A. peltigerinus (Table 1, Fig. 1).
Arrhenia peltigerina. Microscopic features of Agaricus peltigerinus (lectotype) and Omphalina cupulatoides (holotype).
Omphalina cupulatoides (Orton Reference Orton1977) was described as growing on a thallus of Peltigera polydactylon. However, some confusion and discussion was raised on the identity of this agaric species, mainly concerning spore shape (cf. Collin & Lauron Reference Collin and Lauron1994) and colour of basidiomata (cf. Bon Reference Bon1997). It has been considered as a synonym of A. peltigerina (Collin & Lauron Reference Collin and Lauron1994; Vila Reference Vila2002; Garnier-Delcourt Reference Garnier-Delcourt2008; Elborne Reference Elborne, Knudsen and Vesterholt2008; Smith et al. Reference Smith, Aptroot, Coppins, Fletcher, Gilbert, James and Wolseley2009) or as a separate species (Santesson Reference Santesson1993; Bon Reference Bon1997). After examination of the holotype and additional herbarium material deposited in E, we conclude that O. cupulatoides is conspecific with A. peltigerina since no relevant differences were observed in size and shape of spores and basidiomata colour (Table 1, Fig. 2). Thus, we agree with the previous taxonomic treatment carried out by several authors (Collin & Lauron Reference Collin and Lauron1994; Vila Reference Vila2002; Garnier-Delcourt Reference Garnier-Delcourt2008; Elborne Reference Elborne, Knudsen and Vesterholt2008).
For a comparative study, modern material collected by the authors in Spain (AH 32777) has also been used in this work. Macro- and micromorphological features of basidiomata of the Spanish material are illustrated in Fig. 3. Micromorphological features (Fig. 3 B–E) can be compared with those observed in the Agaricus peltigerinus lectotype (Fig. 1) and in the Omphalina cupulatoides holotype (Fig. 2).
In most herbarium specimens studied, the Peltigera thalli are in too poor a state of preservation for an accurate identification.
Additional specimens examined. Spain: Madrid: Canencia, Puerto de Canencia, en el abedular, talud rezumante, sobre Peltigera cf. membranacea, 19 ix 2003, V. J. Rico, J. M. Barrasa & F. Esteve-Raventós (AH 32777).—Great Britain: England: V. C. 11, South Hampshire: New Forest, Woodford Bottom, 1987, P. D. Orton 5832 (E, as O. cupulatoides). Scotland: V. C. 85, Fifeshire, Devilla Forest, alongside track on E side of Forestry nursery, on Peltigera lactucifolia, 200 ft, 14 vii 1985, B. J. Coppins s. n. (E, as O. cupulatoides); V. C. 86, Stirlingshire: Doune Ponds, Doune, on Peltigera lactucifolia, 1990, R. Watling 22554 (E, as O. cupulatoides); V. C. 88 Mid Perthshire: Rannoch: Dall, 1971, P. D. Orton 4193 (E, as Omphalina cupulatoides); ibid.: Blackwood, 1965, P. D. Orton 1403 and 2829 (E, two specimens as O. cupulatoides).
We thank the curators of the NYS and E herbaria for sending us the type material of Agaricus peltigerinus and Omphalina cupulatoides respectively, F. Esteve-Raventós (Alcalá de Henares) for bibliographic advice and D. L. Hawksworth (Madrid) and J. Kokourková (Praha) for encouraging us to study the Velenovský's type material of Cantharellus peltigerae. Three anonymous referees are also thanked for improvements to the manuscript. We acknowledge support from the Spanish Ministerio de Educación y Ciencia (Flora Liquenológica Ibérica project, CGL2007-66734-C03-01) and from BSCH-UCM (GR58/08-910773).
