Pleomorphic conidiation in Claviceps Sylvie PAZ ˇ OUTOVA ´ , Miroslav KOLAR ˇ I ´ K and Renata KOLI ´ NSKA ´ Institute of Microbiology, Czech Academy of Sciences, Laboratory of the Physiology, Genetics and Biotechnology of Fungi, Vı´den ˇska ´ 1083, 142 20 Prague 4, Czech Republic. E-mail : pazouto@biomed.cas.cz Received 7 May 2003; accepted 25 November 2003. Types of asexual sporulation in 17 Claviceps species and the closely related Corallocytostroma ornicopreoides were revised in relation to the phylogeny of clavicipitaceous fungi. We observed : (1) enteroblastic conidiation from branched phialidic conidiophores typical of the genus (anamorph Sphacelia) in all species including Corallocytostroma ; (2) widespread and often sequential formation of terminal holoblastic secondary conidia on tapering hyphae arising from sphacelial macroconidia ; and (3) in addition to sphacelial conidiation, sympodial holoblastic conidiation of the Ephelis-type in cultures of C. zizaniae and in both the culture and sphacelial tissue of C. citrina. Secondary conidiation was not found in C. purpurea, C. citrina and C. sorghicola. During sphacelial fructification, most species produced macroconidia and microconidia. Only macroconidia formed in planta underwent secondary conidiation whereas microconidia did not germinate at all. In C. phalaridis, the formation of holoblastic 2–3 celled appendaged conidia was observed, similar to that of Aciculosporium and Neoclaviceps. In dendrograms based on ITS1-5.8S rDNA-ITS2 sequences, genera and species with appendaged conidia grouped on a highly supported clade with ancestral Corallocytostroma. The clade was placed inside a group of tropical species of Claviceps, without any relationship to Balansiae. INTRODUCTION In the family Clavicipitaceae, several conidiation types and the corresponding anamorphs are known. Ephelis anamorphs produce allantoid to acicular or filiform macroconidia, which are holoblastic, sympodial and often form whorls consisting of 3–8 spores (Rykard & Luttrell 1984, White 1997). Ephelidial anamorphs occur in teleomorphic genera Balansia, Myriogeno- spora (White 1997) and Heteroepichloe¨ (Tanaka et al. 2002). Anamorphs of Claviceps (i.e. Sphacelia), Epichloe¨ (i.e. Neotyphodium) Dussiella, and Cordyceps have phialides, producing endoblastic conidia (White 1997). Endophytic Epichloe¨/Neotyphodium species have phia- lides arranged in sporodochia in planta that form small conidial heads, whereas conidia formed in culture or on germ tubes emerging from ascospores occur mostly singly. These conidia are capable of repeated micro- cyclic conidiation (Bacon & Hinton 1991). Atkinsonella produces either ephelidial macroconidia in groups of 3–5, or Acremonium-like oval micro- conidia (Morgan-Jones & White 1992). In Claviceps, phialidic formation of enteroblastic conidia that remain glued first in heads and later mer- ging in an oozing honeydew mass has been observed both in planta and in culture (Luttrell 1980, Rykard et al. 1984) and is considered the main sporulation type. Also, the formation of secondary conidia is described in C. africana and C. sorghi (Frederickson, Mantle & de Milliano 1989, Pazˇoutova´ & Bogo 2001). However, there are some less known species of Claviceps and allied genera, which differ in their association with host plant and where yet different conidiation was observed. The Australian endemic Cepsiclava phalaridis (syn. Claviceps phalaridis) forms a stable endophytic association with its host plants (Walker 1957, 1970, 2004) which are infected by ascospores making contact with the coleoptile. Sclero- tia occur in every floret of the colonized plant regard- less of their sex, rendering it sterile. Walker (1957) described oblong to cylindrical enteroblastic dry conidia 7.5–14r2–3 mm on the surface of C. phalaridis sclerotia and also filiform holoblastic bicellular conidia (20–25 mm) with dichotomously branched antler-like appendages at the distal end of the apical cell; these latter spores are capable of microcyclic conidiation through proliferation of the basal cell. Almost identical appendaged spores have been observed in cultures of Aciculosporium take, an endo- phyte (Nozu & Yamamoto 1972) causing a witches’ Mycol. Res. 108 (2): 126–135 (February 2004). f The British Mycological Society 126 DOI: 10.1017/S0953756203009067 Printed in the United Kingdom.