2 Pezizomycotina: Pezizomycetes, Orbiliomycetes 1 DONALD H. PFISTER CONTENTS 5. Discinaceae . 47 6. Glaziellaceae. 47 I. Introduction ................................ 35 7. Helvellaceae . 47 II. Orbiliomycetes: An Overview.............. 37 8. Karstenellaceae. 47 III. Occurrence and Distribution .............. 37 9. Morchellaceae . 47 A. Species Trapping Nematodes 10. Pezizaceae . 48 and Other Invertebrates................. 38 11. Pyronemataceae. 48 B. Saprobic Species . ................. 38 12. Rhizinaceae . 49 IV. Morphological Features .................... 38 13. Sarcoscyphaceae . 49 A. Ascomata . ........................... 38 14. Sarcosomataceae. 49 B. Asci. ..................................... 39 15. Tuberaceae . 49 C. Ascospores . ........................... 39 XIII. Growth in Culture .......................... 50 D. Paraphyses. ........................... 39 XIV. Conclusion .................................. 50 E. Septal Structures . ................. 40 References. ............................. 50 F. Nuclear Division . ................. 40 G. Anamorphic States . ................. 40 V. Reproduction ............................... 41 VI. History of Classification and Current I. Introduction Hypotheses.................................. 41 VII. Growth in Culture .......................... 41 VIII. Pezizomycetes: An Overview............... 41 Members of two classes, Orbiliomycetes and IX. Occurrence and Distribution .............. 41 Pezizomycetes, of Pezizomycotina are consis- A. Parasitic Species . ................. 42 tently shown in molecular phylogenetic studies B. Mycorrhizal Species . ................. 42 to diverge at the base of the Pezizomycotina C. Saprobic Species . ................. 42 X. Morphological Features .................... 42 phylogeny (Gernandt et al. 2001; Hansen and A. Ascomata . ........................... 42 Pfister 2006; Spatafora et al. 2006). Kumar et al. B. Asci. ..................................... 43 (2012) give ultrastructural data on the septal C. Ascospores . ........................... 43 structure, ascus wall construction, and nuclear D. Paraphyses. ........................... 43 division that suggest the Orbiliomycetes repre- E. Septal Structures . ................. 44 F. Anamorphic States. ................. 44 sent the earliest diverging lineage of the Pezi- XI. Reproduction ............................... 44 zomycotina. The relationship of these two XII. History of Classification and Current classes and the family diversity within the Pezi- Hypotheses.................................. 44 zomycetes are shown in Fig. 2.1. These two A. Families of the Pezizomycetes . ....... 46 groups show very few shared characteristics 1. Ascobolaceae . ................... 46 2. Ascodesmidiaceae. ................... 46 other than the formation, for the most part, of 3. Caloscyphaceae. ................... 46 well-developed apothecial ascomata in which 4. Chorioactidaceae. ................... 46 asci are generally arranged in a hymenium with paraphyses. Orbiliomycetes was recog- nized as a class only recently (Baral 2003). 1Farlow Herbarium and Library of Cryptogamic Botany, Department of Organismic and Evolutionary There is a single order, Orbiliales, and a single Biology, Harvard University, Cambridge, MA, 02138, USA; family, Orbiliaceae, with perhaps 300 species e-mail: dpfi[email protected] currently arranged in three teleomorphic Systematics and Evolution, 2nd Edition The Mycota VII Part B D.J. McLaughlin and J.W. Spatafora (Eds.) © Springer-Verlag Berlin Heidelberg 2015 36 D.H. Pfister Fig. 2.1 A diagrammatic representation of the relation- received maximum parsimony, posterior probability, ships of the Pezizomycetes and Orbiliomycetes, includ- and maximum-likelihood support 75 %, 95 %, and ing the families of the Pezizomycetes, based on Hansen 75 %, respectively, are in bold et al. (2013) and Pfister et al. (2013). Branches that Pezizomycotina: Pezizomycetes Orbiliomycetes 37 genera. An early diverging position of the class In this chapter, the two classes are treated has been confirmed by morphological studies independently in separate sections. and molecular phylogenetic analyses (Kumar et al. 2012; Spatafora 2006; Wang et al. 2006). Previously, the Orbiliaceae was placed among II. Orbiliomycetes: An Overview the Helotiales as a family based on Nannfelt’s (1932) classic work on the nonlichenized inop- The family Orbiliaceae was proposed by Nann- erculate discomycetes. The Pezizomycetes feldt (1932) and was restricted to those fungi have long been recognized to include a single with small so-called inoperculate asci, minute order, the Pezizales, and include 16 families ascospores, and a waxy texture. The asci and and approximately 1,200 species. The group, paraphyses are often agglutinated. Nannfeldt in whole or in part, has been the subject of illustrated several species showing details of recent surveys (Hansen and Pfister 2006; Har- the thin-walled globose to angular cells of the rington et al. 1999; Perry et al. 2007; Pfister excipulum. A monograph on the genus Orbilia et al. 2008). by Svrcek (1954) included 16 species that were In regard to morphological characteristics distinguished based on ascospore size and and ecology, the two classes also are distinct. shape, the color of the ascomata, and the form The Orbiliomycetes are saprobic and in some of the paraphyses. The groundbreaking work of cases supplement their nutrition through the Hans-Otto Baral and his collaborator, Guy Mar- capture and consumption of small inverte- son, has led to a refinement of the family and brates. Their spores are small, nonseptate recognition of many more species. Kirk et al. (save for a single example), uninucleate, and (2008) proposed 288 species, but the extent of contain a membrane-bound structure, the the diversity to be described is in flux. A mono- spore body (Baral 1994; Benny et al. 1978; graph has been in preparation by Baral for Kumar et al. 2012). Spores are discharged many years. Modern methods employ morpho- actively. Asci are small and generally lack a logical and histochemical characters previously well-developed apical apparatus. Anamorphic not used and incorporate ecological characters states are frequently formed, and their number as well. Of particular note is the reliance on has increased steadily in the literature in recent fresh, living material (Baral 1992). There has years. Species are found on dung, on wet wood been a burst of activity focusing on the descrip- on the forest floor, in water-soaked areas where tion of teleomorphic taxa and associated ana- they are somewhat ephemeral, or on dead wood morphs (e.g., Kohlmeyer et al. 1998; Liu et al. hanging in trees where, because of their 2005a, b, 2006; Mo et al. 2005; Pfister 1994; drought resistance, they are persistent (Baral Pfister and Liftik 1995; Qiao et al. 2011; Qin 2011). No species are plant parasitic. et al. 2010; Su et al. 2011; Tanabe et al. 1999; The Pezizomycetes are saprobic, plant par- Webster et al. 1998; Wu et al. 2007; Yang and asitic, or associated with plants as ectotrophic Liu 2005; Yu et al. 2007a, b, c, 2011; Zhang et al. mycorrhizae (Hansen and Pfister 2006; Teder- 2007), and in this work there has been an soo et al. 2006; Wei et al. 2010). The ascomata intense interest in the diversity and functional are always to some degree ephemeral. Spores morphology of the anamorphic states. This is are large, generally more than 10 mm and may particularly the case regarding those that reach a length of 60 mm, and single-celled. capture nematodes, i.e., species referred to Spores generally are actively discharged Arthrobotrys and allied form genera. through a well-developed opening created by the rupture of the ascus wall forming an oper- culum that is either terminal or eccentric in position. The trufflelike habit has developed III. Occurrence and Distribution independently in several lineages across the class (Læssøe and Hansen 2007). These hypo- Members of the Orbiliomycetes are found geous taxa generally do not have active spore around the world in boreal to tropical habitats. release. Furthermore, several species complexes, such 38 D.H. Pfister as O. luteorubella and O. xanthostigma, that addition to trapping nematodes, some hypho- represent morphologically very similar collec- mycetes in the orbiliaceous lineage trap other tions seem to be found broadly distributed small invertebrates such as collembolans and around the world and across latitudes. There rhizopods (e.g., Barron 1981; Drechsler 1936, are two major ecological groups—those that 1937b). Even though these fungi may occur on occur in moist habitats such as on dung, old wood or cellulose-rich substrates, there is evi- polypores, and moist wood on the forest floor dence that few of the nematode-trapping fungi or near streams and species that are drought are able to break down cellulose (Park et al. tolerant. These drought-tolerant species are 2002). found on dead twigs and small woody branches in the canopy of living trees. Often species of both ecological types are found in association B. Saprobic Species with unicellular green algae, but there is no evidence that the fungi are lichenized. Until the work of Baral (2011) and Marson, most studies of diversity within the Orbiliomycetes were focused on those species on moist sub- A. Species Trapping Nematodes strates. The discovery that these fungi are and Other Invertebrates highly diverse in the dry habitats of hanging branches in living trees has greatly expanded Since the classic work of Drechsler (1937a)on the