This Article Abstract Full Text (PDF) Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Healy, R. A. Search for Related Content PubMed Articles by Healy, R. A. Agricola Articles by Healy, R. A.

Mattirolomyces tiffanyae, a new truffle from Iowa, with ultrastructural evidence for its classification in the Pezizaceae

     Bessey Microscopy Facility, Iowa State University, Ames, Iowa 50011-1020

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 

A new species of hypogeous Pezizales, Mattirolomyces tiffanyae, is described and illustrated. Its asci are typically three-spored, an unusually small number in the non-Tuber Pezizales. Ascus septal pore ultrastructure consists of a uni- or bi-convex band, which suggests an affinity with the Pezizaceae. Secondary spore-wall development is similar to that of Peziza, and several species of hypogeous Pezizaceae.

Key words: Hydnobolites, hypogeous ascomycete, septal pore, Terfezia, Terfeziaceae

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
Truffles, hypogeous Ascomycota, are difficult to identify due to the evolutionary convergence of morphological characters among taxa that share a similar habitat and mode of spore dispersal. Truffles develop below the soil surface and remain below the soil surface, or sometimes emerge at maturity. Most are known or suspected to be ectomycorrhizal (Maia et al 1996, Trappe and Maser 1977), and spores either are released passively into the soil from disintegrated asci and ascocarps or dispersed through mammal mycophagy (Johnson 1996, Maser and Maser 1987, Maser et al 1978, Trappe and Maser 1977). Salient features, such as the mode of ascus dehiscence, morphology of the ascus tip, and amyloid reactions of asci in Melzer's solution that phylogenetically are useful in the classification of epigeous Ascomycota, usually are altered in hypogeous Ascomycota so that relationships cannot be discerned on the basis of these characters.

Morphological and molecular evidence is accumulating for the independent derivation of truffles, with the exception of Elaphomyces, from at least three families within the epigeous Pezizales (Kimbrough 1994, O'Donnell et al 1997, Percudani et al 1999). Septal pore ultrastructure is one morphological character that appears to correlate well with molecular sequence analysis of the18S rDNA in the Pezizales. The Pezizales have a unique lamellate structure associated with septal pores of vegetative hyphae. Septal pore ultrastructure at the base of the ascus appears to be consistent within families of the Pezizales (Kimbrough 1994) and has been interpreted to link several truffles to epigeous families (Li and Kimbrough 1994, Kimbrough et al 1991, 1996). Another useful taxonomic character is spore-wall development. Early secondary spore-wall development appears to be consistent among taxa within the Pezizaceae (Dyby and Kimbrough 1987, Merkus 1975, 1976). The final stages of spore-wall ornamentation differ among species (Dyby and Kimbrough 1987).

A new species of Mattirolomyces Fischer was found during studies of truffles and false truffles in Iowa. It is here described and illustrated. To help establish the phylogenetic affinities of this taxon, the ultrastructure of septal pores and spore-wall development were examined.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
Fresh material – Water mounts of sections from fresh ascocarps were used to study peridial and glebal anatomy of ascocarps and of asci. Fifty mature ascospores were measured, and asci were observed for color change in Melzer's solution. Descriptions of this material follow suggestions and terminology of Weber et al (1997).

Microscopy – Two specimens were prepared for TEM following Curry and Kimbrough (1983). Resin-embedded blocks were thin-sectioned to 55 nm with a Diatome diamond knife (Diatome-U.S., Fort Washington, Pennsylvania) on a Reichert Ultracut S ultramicrotome (Leica, Wien, Austria) and 3–4 sections picked up in a drop of water with a single slot copper grid and deposited on a Formvar coated rack by the method of Rowley and Moran (1975). Sections were stained with uranyl acetate and lead citrate and viewed with 80 kV on a JEOL 1200EX scanning transmission electron microscope (JEOL USA Inc., Peabody, Massachusetts) (TEM). Images were captured on Kodak Electron Image Film SO-163 (Eastman Kodak, Rochester, New York) or captured digitally with an SIS Megaview III camera (Lakewood, Colorado). For each set of thin sections, a section 1 µm thick was collected and placed on a glass slide, stained with toluidine blue O, mounted in Permount on a drop of xylene and coverslipped. Thick sections were studied with bright-field optics for median sections through septae at the bases of asci, and those so identified were circled on a digital image of the section. The circled septae then were used as a guide when searching thin sections with TEM for septae at the base of asci.

For light microscopy, one specimen was fixed in FAA and processed for paraffin embedding (Ruzin 1999). Sections 8 µm thick were stained with iron hematoxylin and mounted in Permount for viewing of general morphology. Light micrographs were taken on a Leitz Orthoplan compound microscope with a Leica WILD MPS 52 camera system (Leica, Wien, Austria) or digitally captured with a Zeiss AxioCam HRc camera system (Thornwood, New York). For scanning electron microscopy (SEM), 50 µm sections were cut from paraffin-embedded blocks, deparaffinized in xylene, transferred to 100% ETOH, critical-point dried in a DCP-1 Denton Critical Point Drying Apparatus (Denton Vacuum Inc., Cherry Hill, New Jersey), mounted on aluminum stubs, with double-sided tape, painted around the edges with silver paint, sputter-coated with Au/Pd and viewed with 15 kV in a JEOL 5800LV SEM (JEOL USA Inc., Peabody, Massachusetts). Images were digitally captured.

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
During a project conducted 1996–2000 to find and catalogue truffles and false truffles in Iowa, an undescribed species was collected at several sites in Story County. It is here described and documented as a new species.

Mattirolomyces tiffanyae Healy, sp. nov. Figs. 1–25

View larger version (157K): [in this window] [in a new window]   FIGS. 1–10. M. tiffanyae 1. Sectioned ascocarp; bar = 5 mm. Figs. 2–3. Bright-field microscopy (BFM). 2. Peridium; bar = 50 µm. 3. Ascus; bar = 25 µm. 4. Scanning electron microscopy of mature ascospore in a sectioned ascus; bar = 5 µm. Figs. 5–8, 10. Transmission electron microscopy (TEM). 5. Lamellate structures in septal pore of glebal hypha with globose Woronin bodies (W); bar = 500 nm. 6. Lamellate structures in septal pore of glebal hypha; bar = 250 nm. 7. Ascus (A) with bi-convex band in septal pore (arrow), and vesicles in mound of differentiated ascosplasm overlaying septal pore; bar = 3 µm. 8. Higher magnification of Fig. 7, bi-convex band and vesicles in ascus (A); bar = 250 nm. Fig. 9. BFM of toluidine blue O stained asci (A) produced from ascogenous hyphal cell; bar = 20 µm. 10. Same ascogenous cell as in Fig. 9, tipped slightly counterclockwise, with bi-convex band in septum at the base of ascus (A). Note Woronin bodies (W) in cell subtending ascus, and seven nuclei (N); bar = 3 µm

Stereothecium subglobosum, usque ad 17 x 15 mm, odore fungi, pagina puberula, ceterum aequata, alba, immutabili. Peridium ex constans textura intricata. Gleba a peridio non separabilis, solida, alba, marsupio fertilibus in sicco cremicoloribus, venis sterilibus immutabilibus. Asci ellipsoidei, haud amyloidei, persistentes, unispori ad quadrispori. Paraphyses carentes. Sporae hyalinae, uniguttulatae, globosae, 29–33.6 µm diam ornamentis inclusis, verrucatis ad porcatis et ex partibus reticulatis, ornamentis 2.5–5 µm altis.

Holotypus hic designatus: U.S.A., Iowa: Story County, 18 Aug 1998, Healy, R. 231 (HOLOTYPE: ISC; ISOTYPE: BPI, OSC)

Fruit body structure – Ascocarp a stereothecium, often with small holes indicating mycophagous activity, subglobose, the largest 17 x 15 mm, with a mushroom-like odor, the surface finely pubescent, the mycelial hairs sparse, septate, short, up to 113 µm x 13.8 µm, otherwise the surface even, white, unchanging. Not staining where handled or damaged. No rudimentary basal stipe or mycelial tuft (Fig. 1). Peridium of textura intricata (Fig. 2). Peridial hyphae 5–17.5 µm in diam at the septum, often inflated, continuous with and similar to hyphae of sterile veins in gleba. Walls of outermost peridial hyphae up to 2 µm thick. Gleba solid, white, with fertile pockets that dry to cream-colored and sterile veins remaining unchanged.

Asci inoperculate, non-amyloid in Melzer's solution, irregularly arranged in fertile pockets of gleba, ellipsoidal, 110–139 µm x 53–63 µm, short pedicellate, 1–3 (4)-spored, with usually 3 uncrowded, globose spores irregularly uniseriate to inordinate (Fig. 3). Paraphyses absent. Spores within same ascus frequently in different stages of development (not shown). Spores hyaline, with one guttule, globose, 22.5–26.8 µm diam, with a mean of 24.6 µm diam excluding ornamentation, 29–,33.6 µm diam, with a mean of 31.3 µm diam including ornamentation; hyaline in water, unchanging to pale yellow in Melzer's solution. Mature spores ornamented with flat-topped spines and ridges forming a partial reticulum, irregular in thickness, 2.5–5 µm high, with a mean of 3.7 µm (Fig. 4).

Habitat.—Hypogeous to emergent in Hayden-Lester-Storden association soil formed from glacial till, in mixed deciduous upland woods composed of Quercus macrocarpa Michx., Acer saccharum Marsh., Carya ovata (Mill.) K. Koch, Prunus serotina Ehrh., Tilia americana L., and Ulmus L. sp., or Q. alba L. and Ostrya virginiana (Mill.) K. Koch.

Paratypes: U.S.A. Iowa, Story County, McFarland Park (42°06'00'' N, 93°34'30'' W), near Ames, col. R. Healy, 23 Aug 1998 RH 237 (ISC); Story County, Hickory Grove Park (41°59'30'' N, 93°21'30'' W), near Nevada, col. R. Healy, 1 Sep 1998 RH 251 (ISC); 7 Sep 1998 RH 257 (ISC); 17 Sep 1998 RH 274 (ISC); 6 Aug 1999 RH 520 (ISC); Reactor Woods (42°02'30'' N, 93°39'20'' W), Ames, col. C. Notis 28 Aug 1999 RH 556 (ISC); col. R. A. Healy 3 Oct 1999 RH 601 (ISC).

Etymology – It is my pleasure to name this taxon for Dr. Lois Hattery Tiffany. For more than half a century at Iowa State University, she fostered a broad range of mycological studies with many students but always has maintained a particular interest in the hypogeous fungi.

Septal pore ultrastructure – Septal pores in glebal hyphae were viewed with TEM. Ascogenous hyphae were indistinguishable from other glebal hyphae and therefore only identified as such where they were connected to an ascus. Some glebal hyphae have "Peziza type septal pore" structures (Kimbrough 1994) of alternating electron-dense and electron-translucent bands (Figs. 5, 6). Median sections through septal pores at the base of asci display bi-convex bands (Fig. 8, a higher magnification of Fig. 7; and Fig. 11, a higher magnification of Figs. 9, 10) and uni-convex bands (Fig. 12) similar to those found in the Pezizaceae (Curry and Kimbrough 1983) and Terfeziaceae (Janex-Favre et al 1988). Woronin bodies are spherical (Fig. 5), consistent with those of the Pezizaceae (Kimbrough 1994) and sometimes observed in ascogenous hyphae (Fig. 10). Vesicles are observed within a hemispherical mound of differentiated ascoplasm separated from the main portion of the ascus by a membrane and situated over the septal pore at the base of the ascus (Figs. 7, 8, 10, 11). Similarly, the ascoplasm situated over septal pores with uni-convex bands is differentiated and separated from the remainder of the ascoplasm (Fig. 12).

View larger version (163K): [in this window] [in a new window]   FIGS. 11–12. TEM of septal pores. 11. Higher magnification of Fig. 10, bi-convex band at base of ascus (A); bar = 250 nm. 12. Uni-convex band at base of older ascus (A); bar = 250 nm. FIGS. 13–25. TEM of secondary spore wall development in M. tiffanyae. 13. young spore with electron-translucent primary wall (PW) and outpouching (outlined region) of the investing membrane (IM) into the epiplasm (EP); bar = 3 µm. 14. Higher magnification of outlined region in Fig. 13, electron-dense material between IM and PW; bar = 250 nm. 15. Elongation and evagination of IM into EP to create perisporal sac (PS); bar = 3 µm. 16. Spore with voluminous PS, filled with flocculose substance and surrounded by epiplasmic vacuoles (V); bar = 3 µm. 17. Higher magnification of outlined region in Fig. 16, showing alignment of tonoplasts (T) with IM; bar = 700 nm. 18. Development of epispore precursor with electron-dense bodies (DB) in V and PS; bar = 3 µm. 19. Higher magnification of region outlined in Fig. 18, showing DB in PS and development of epispore precursor (arrow) of short fibrils perpendicular to PW; bar = 500 nm. 20. Deposition of DBs on epispore precursor (arrow); bar = 250 nm. 21. Striate DB separated from epispore (ES) by zone of electron translucence (ETZ); bar = 250 nm. 22. Nearly mature spine with striate ES, column of fibrils separated from electron-dense cap by ETZ; bar = 500 nm. 23. BFM of nearly mature spore showing spine caps (arrows) stained dark in toluidine blue O, and copious EP; bar = 10 µm. 24. Spore spine of compact fibrils with margins of loosely arranged fibrils; bar = 500 nm. 25. Mature spore spine of compact fibrils with margins of loosely arranged fibrils overlaid by collapsed IM and T; bar = 500 nm

Secondary wall formation begins with an epispore precursor, which develops as short fibrils perpendicular to the primary wall (Figs. 18–20). Hemispherical electron-dense condensed material is deposited on top of the epispore precursor (Figs. 18–20). It is separated from the epispore by a thin zone of electron translucence and appears to be striate (Fig. 21). This material is deposited in irregularly spaced mounds of variable breadth until spines or ridges (Figs. 22–24) are formed. The tips of the spines and ridges sometimes are capped with electron-dense material (Fig. 22) that also stains densely with toluidine blue O (Fig. 23). The cap material is similar in appearance to that deposited on the epispore (Fig. 21). The electron-dense cap is separated from the spine column by a thin zone of electron translucence (Fig. 22). The electron-dense cap is compact and condensed (Fig. 22), while the underlying secondary wall obviously is fibrillar (Fig. 22). The epispore becomes compact (Fig. 21) and striated with electron-dense and electron-translucent zones (Fig. 22) as ornamentation proceeds. The electron-dense cap material is not apparent on the most mature spores (Fig. 24). Late in development of the secondary wall, the spine differentiates into an inner, compact, moderately electron-dense column of fibrils surrounded by more loosely arranged fibrils, less electron dense than the inner column (Fig. 25), and the tonoplast/investing membrane complex degenerates and collapses over the spines and ridges (Fig. 25). The spines and ridges of mature spores are viewed readily with SEM (Fig. 4).

As in other taxa of the Pezizaceae, the mature spore contains a large, single, central, lipid droplet (Fig. 23) (Dyby and Kimbrough 1987). Secondary wall development coincides with the vacuolization and disappearance of epiplasm. The epiplasm is interpreted here as it has been by other investigators (Mainwaring 1972, Merkus 1976) to contribute material destined for the secondary wall. In a deviation from spore development in the epigeous Pezizaceae, there is sometimes a considerable amount of epiplasm remaining at spore maturity (Fig. 23).

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
Fischer erected the genus Mattirolomyces (Terfeziaceae) to accommodate a taxon similar in appearance to Terfezia that differed in ascocarp shape and ascus characters. Ascocarps in Mattirolomyces are relatively spherical rather than turbinate in shape because they lack the base usually present in Terfezia, and the asci are 2–3 times longer than wide, with uncrowded, irregularly uniseriate to biseriate arranged spores rather than the ellipsoidal to globose asci, with crowded, inordinately arranged spores of Terfezia (Fischer 1938). Trappe (1971) subordinated Mattirolomyces to a subgenus of Terfezia because the delimiting characters also were found in some species of Terfezia. Trappe's circumscription of Terfezia subgenus Mattirolomyces included these species, each described with a pallid gleba, elongate asci with uncrowded spores, and spores with a partial to complete reticulum: T. austroafricana Marassas and Trappe, T. decaryi Heim, T. terfezioides (Matt.) Trappe and T. spinosa Harkn. (Marasas and Trappe 1973). Of these, T. spinosa is the only species from North America. Results from recent molecular analyses that included T. terfezioides among the taxa sampled support the reinstatement of the genus Mattirolomyces (Diez et al 2002, Norman and Egger 1999, Percudani et al 1999), an interpretation that Trappe agrees with (pers comm). Diez et al (2002) noted that Terfezia differs from Mattirolomyces in ecology and in geographic distribution. Terfezia is found in arid to semi-arid environments and is mycorrhizal with herbaceous species of Cistus and Helianthemum. Mattirolomyces terfezioides is found in temperate forests, and there is evidence that it forms ectendomycorrhizae with Robinia pseudoacacia, a woody plant (Bratek et al 1996).

Before the folding of Mattirolomyces into Terfezia, M. terfezioides was the only species described. A reassessment of Terfezia is needed to determine whether any other species should be transferred to Mattirolomyces. T. spinosa differs from M. terfezioides mainly in larger spore size and longer spore spines (Gilkey 1947, Montecchi and Sarasini 2000). Mattirolomyces tiffanyae differs from M. terfezioides and from species currently classified as Terfezia subgenus Mattirolomyces in the small number of spores per ascus, the large spore size, and the spore ornamentation of blunt spines and ridges forming a partial reticulum, the mesh of which varies in thickness. These same characters, along with a solid gleba distinguish M. tiffanyae from Hydnobolites, which has hollow or hypha-stuffed glebal canals that are lined with a hyphal layer similar to that of the peridium. Delastria rosea Tul. and Tul.is similar to M. tiffanyae in ascus shape and number of spores per ascus but differs in the alveolate-reticulate ornamentation of its spores, the wide variation of spore sizes and ornamentation within a single ascocarp and the color of its gleba, which is pinkish to brown and stains pinkish when touched.

It is hypothesized that many of the Terfeziaceae are hypogeous Pezizaceae (Kimbrough et al 1991). There is morphological evidence to support classification of Hydnobolites (Kimbrough et al 1991) in the Pezizaceae and molecular evidence to support classification of Mattirolomyces (as T. terfezioides), Pachyphloeus and Terfezia (Percudani et al 1999) in the Pezizaceae. Results from this study give ultrastructural evidence to support the classification of M. tiffanyae in the Pezizaceae.

It is unusual within the epigeous Pezizales for asci to produce fewer than eight spores but less unusual among hypogeous Pezizales. Among the Terfeziaceae, Delastria rosea Tul. and Tul. is the only species with fewer than five spores per ascus. It is possible that the less mature spores in asci of M. tiffanyae, with multiple stages of spore development, were in the process of aborting. However, abortion of spores would not explain why initially there were fewer than five spores per ascus. An investigation of spore ontogeny up to the time of spore delimitation would be informative regarding the fate of postmitotic nuclei in this taxon, which could shed light on why so few spores develop within a given ascus.

Secondary spore-wall development in M. tiffanyae is similar to that found in the Pezizaceae and Terfeziaceae (Table I), although wall ornamentation of species of Peziza were less complex than Mattirolomyces. Deposition of both the epispore and the ornaments is by direct precipitation, as found also in the Pezizaceae (Wu 1991) and in Hydnobolites, a member of the Pezizaceae previously classified in the Terfeziaceae (Kimbrough et al 1991), rather than the gradual condensation reported in the Humariaceae (Wu and Kimbrough 1991). Among members of the Pezizaceae and Terfeziaceae, secondary spore-wall development of M. tiffanyae is most similar to that of H. cerebriformis but differs in the lack of a complete reticulum and in the variable thickness of the ridges that form a partial reticulum. It also is similar to that in T. leptoderma and T. claveryi but differs most notably in the latter stages, where an electron-dense cap forms on the spine tips and ridges of M. tiffanyae but covers the spine tips and valleys on spores of Terfezia. The final stage of ornamentation in M. tiffanyae, where the fibrillar columns are compact and dense in the center and more loosely arranged along the periphery, is similar to that found in H. cerebriformis but not reported in species of Terfezia.

	ACKNOWLEDGMENTS

	FOOTNOTES

 
¹ E-Mail: rhealy{at}iastate.edu

Accepted for publication April 1, 2003.

	LITERATURE CITED

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
Bratek Z, Jakucs E, Bóka K, Szedlay G., 1996 Mycorrhizae between black locust (Robinia pseudoacacia) and Terfezia terfezioides. Mycorrhiza 6:271-274

Carroll GC., 1969 A study of the fine structure of ascosporogenesis in Saccobolus kerverni. Arch Mikrobiol 66:321-339

Curry KJ, Kimbrough JW., 1983 Septal structures in apothecial tissues of the Pezizaceae (Pezizales, Ascomycetes). Mycologia 75:781-794

Díez J, Manjón JL, Martin F., 2002 Molecular phylogeny of the mycorrhizal desert truffles (Terfezia and Tirmania), host specificity and edaphic tolerance. Mycologia 92:247-259

Dyby SD, Kimbrough JW., 1987 A comparative ultrastructural study of ascospore ontogeny in selected species of Peziza (Pezizales; Ascomycetes). Bot Gaz 148:283-296

Fischer E., 1938 Klasse Ascomycetes, Reihe Euascales. Unterreihe VIII. Tuberineae. In: Engler A, Harms H., eds. Die Natürlichen Planzenfamilien 5b. Leipzig: Verlag Von Wilhelm Engelmann. p 35–39 .

Gibson JL, Kimbrough JW., 1988 Ultrastructural observations on Helvellaceae (Pezizales). Ascosporogenesis of selected species of Helvella. Can J Bot 66:771-783

Gilkey HM., 1947 New or otherwise noteworthy species of Tuberales. Mycologia 39:441-452

Janex-Favre MC, Parguey-Leduc A., 1985 Les asques et les ascospores du Terfezia claveryi Ch. (Tuberales). Cryptogam Mycol 6:87-99

———, ———, Riousset L., 1988 L'ascocarpe hypoge d'une Terfez Francaise (Terfezia leptoderma Tul., Tuberales, Discomycetes). Bull Soc Mycol Fr 104:145-178

Johnson CN., 1996 Interactions between mammals and ectomycorrhizal fungi. Tree 11:503-507

Kimbrough JW., 1994 Septal ultrastructure and ascomycete systematics. In: Hawksworth DL., ed. Ascomycete systematics: problems and perspectives in the nineties. New York: Plenum Press. p 127–141 .

———, Li LT, Wu CG., 1996 Ultrastructural evidence for the placement of the truffle Barssia in the Helvellaceae (Pezizales). Mycologia 88:38-46

———, Wu CG, Gibson JL., 1991 Ultrastructural evidence for a phylogenetic linkage of the truffle genus Hydnobolites to the Pezizaceae (Pezizales, Ascomycetes). Bot Gaz 152:408-420

Li LT, Kimbrough JW., 1994 Ultrastructural evidence for a relationship of the truffle genus Genea to Otideaceae (Pezizales). Int J of Plant Sci 155:235-243

Maia LC, Yano AM, Kimbrough JW., 1996 Species of Ascomycota forming ectomycorrhizae. Mycotaxon 57:371-390

Mainwaring HR., 1967 The role of endoplasmic reticulum in ascomycete spore delimitation. J Cell Biol 35:86A-87A

———. 1972 The fine structure of ascospore wall formation in Sordaria fimicola. Archiv für Mikrobiologie 81:126-135[Medline]

Marasas WFO, Trappe JM., 1973 Notes on Southern African Tuberales. Bothalia 11:139-141

Maser C, Maser Z., 1987 Notes on mycophagy in four species of mice in the genus Peromyscus. Great Basin Naturalist 47:308-313

———, Trappe JM, Nussbaum RA., 1978 Fungal–small mammal interrelationships with emphasis on Oregon coniferous forests. Ecology 59:799-809

Merkus E., 1975 Ultrastructure of the ascospore wall in Pezizales (Ascomycetes)—III Otideaceae and Pezizaceae. Persoonia 8:227-247

———. 1976 Ultrastructure of the ascospore wall in Pezizales (Ascomycetes)—IV Morchellaceae, Helvellaceae, Rhizinaceae, Thelebolaceae, and Sarcoscyphaceae. General discussion. Persoonia 9:1-38

Montecchi A, Sarasini M., 2000 Funghi ipogei d'Europa. Associazione Micologica Bresadola, Fondazione Centro Studi Micologici. Vicenza. 714 p

Norman JE, Egger KN., 1999 Molecular phylogenetic analysis of Peziza and related genera. Mycologia 91:820-829

O'Donnell K, Cigelnik E, Weber N, Trappe JM., 1997 Phylogenetic relationships among ascomycetous truffles and the true and false morels inferred from 18s and 28s ribosomal DNA sequence analysis. Mycologia 89:48-65

Percudani R, Trevisi A, Zambonelli A, Ottonello S., 1999 Molecular phylogeny of truffles (Pezizales: Terfeziaceae, Tuberaceae) derived from nuclear rDNA sequence analysis. Mol Phylogenet Evol 13:169-180[Medline]

Read ND, Beckett A., 1996 Ascus and ascospore morphogenesis. Mycol Res 100:1281-1314

Rowley CR, Moran DT., 1975 A simple procedure for mounting wrinkle-free sections on Formvar-coated slot grids. Ultramicroscopy 1:151-155[Medline]

Ruzin SE., 1999 Plant microtechnique and microscopy. New York: Oxford University Press. p 41–65 .

Trappe JM., 1971 A synopsis of the Carbomycetaceae and Terfeziaceae (Tuberales). Trans Br Mycol Soc 57:85-92

———, Maser C., 1977 Ectomycorrhizal fungi: interactions of mushrooms and truffles with beasts and trees. In: Walters T, ed. Mushrooms and man, an interdisciplinary approach to mycology. Albany: Linn-Benton Community College. p 165–179 .

———, Sundberg WJ., 1977 Terfezia gigantea (Tuberales) in North America. Mycologia 69:433-437

Weber NS, Trappe JM, Denison WC., 1997 Studies on Western American Pezizales. Collecting and describing ascomata—macroscopic features. Mycotaxon 61:153-176

Wu CG., 1991 Ultrastructural investigations of Humariaceae (Pezizales, Ascomycetes): spore ontogeny, septal structure, and phylogeny [PhD Dissertation]. Gainesville, Florida: Univ. Florida. 262 p .

———, Kimbrough JW., 1991 Ultrastructural investigation of Humariaceae (Pezizales, Ascomycetes). II. Ascosporogenesis in selected genera of the Ciliarieae. Bot Gaz 152:421-438

This Article Abstract Full Text (PDF) Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Healy, R. A. Search for Related Content PubMed Articles by Healy, R. A. Agricola Articles by Healy, R. A.