Paul L. Lentz

Ascospores, Germ Pores, Ultrastructure, and Thermophilism of Chaetomium

SUMMARY Ascospores of 15 isolates of Chaetomium thermophile were compared with those of 105 other Chaetomium species by use of light microscopy and scanning electron microscopy. Two stable characteristics distinguished C. thermophile ascospores from those of all other Chaetomium species examined: a papillate germ pore and pustulate surface ornamentation. Transmission electron microscopy revealed multilayered walls in ascospores of C. semen-citrulli and C. thermophile. In addition, germ pores were confirmed as thin areas in ascospore wall layers. Germinated ascospores of C. semen-citrulli contained several nuclei, mitochondria, fibrillar bundles, vacuoles, and glycogen-like particles.

TWO NEW GENERA OF LEAF-PARASITIC FUNGI (BASIDIOMYCETIDAE: BRACHYBASIDIACEAE)

SUMMARY Proliferobasidium and Ceraceosorus (Brachybasidiaceae, Brachybasidiales, Basidiomycetes) are described as new genera. Both cause leaf-spot diseases of vascular plants and are characterized by persistent thick-walled probasidia and bisterigmate metabasidia. They differ from Dicellomyces, the most closely related genus, in having indeterminate rather than determinate hymenial thickening and in lacking a fruiting body with extensive sterile tissue. Proliferobasidium is based on P. heliconiae, described as a new species on Heliconia bihai. It has intercellular hyphae and exhibits repeated percurrent proliferation of new basidia from within persistent probasidial walls. Ceraceosorus, with the type species Dicellomyces bombacis on Bombax ceiba, has intracellular hyphae and lacks percurrent proliferation of basidia. Ceraceosorus bombacis is presented as a new combination. Since they have features in common with Uredinales, Dacrymycetales, and corticioid Homobasidiomycetes, Ceraceosorus and Proliferobasidium may prove to be of considerable evolutionary interest.

The Fungus Causing Pecky Cypress

In a preliminary report on the cause of pecky decay of bald cypress, Taxodium distichum (L.) Rich. (5), it was stated that basidiocarps of a Stereum had been collected from this host and that cultures derived from spores of this Stereum were similar to cultures isolated from typical pecky decay. In the present paper this Stereum is described as a new species and compared with the better known S. sulcatum Burt, which it closely resembles. Several specimens of the cypress Stereum have been collected in the past by pathologists interested in cypress decay. Von Schrenk obtained a specimen, apparently from a cypress log, in Louisiana in March 1898. This is the specimen reported from Louisiana by Burt (2) as S. sulcatum. Long collected specimens of the same species on a cypress log in Texas in May 1918. Neither Long (16) nor von Schrenk (29) indicated that this Stereum might be connected with pecky cypress. One other specimen was collected by A. S. Rhoads near Gainesville, Florida, in December 1943. These three basidiocarp specimens and the one recently collected in Mississippi (5) suggest that the fungus is widespread on cypress in the South. Collections made since this study was started indicate that the species is common in mature cypress stands. The Stereum on cypress is especially interesting because its basidiocarps resemble those of S. sulcatum; however, on more careful examination, differences are apparent. Cultures of the two are quite distinct; those of S. sulcatum obtained from hosts such as Engelmann spruce, Picea engelmannii Parry, and hemlock, Tsuga canadensis (L.) Carr., show no resemblance to cultures of the species on cypress. These differences are detailed in the following descriptions.

Delineations of forest fungi

Several forest fungi, primarily species that occur in Mississippi, are discussed, and three species are described as new. These includeBotryobasidium (subgenusBrevibasidium)croceum Lentz,Tharoopama mississippiensis Lentz, andHarpographium zonatum Lentz.Dactylium leptosporum (Sacc.)Lentz is recognized as a distinct species, rather than as a subspecies ofD. dendroides Fr. Allescheriella crocea (Mont.)Hughes,D. leptosporum andMelanographium cookei M. B. Ellis are reported from Mississippi for the first time. Attention is called to the fact thatM. citri (Fragoso &Ciferri)M. B. Ellis apparently has not previously been reported from the United States, although a specimen from Florida is in the National Fungus Collections.B. croceum evidently represents the basidiophorous stage ofA. crocea.

Scytinostroma galactinum as a pathogen of woody plants

Scytinostroma galactinum (Fr.)Donk is the fungus commonly known asCorticium galctinum (Fr.)Burt. Although it occurs as a saprobe on woody plants and plant debris, it also has been considered by several authors as an active pathogen that causes a white root and butt or collar rot. During the summer of 1970, it was found near Baltimore and also in Montgomery County, Maryland, under circumstances that seemingly provide additional records of pathogenicity. Several other Maryland records are cited, and many Canadian studies have been reviewed.S. galactinum has a distinctive dextrinoid mycelium, which is characteristic enough to permit a tentative identification even in the absence of other features. Outstanding elements of the basidiocarp are the dextrinoid hyphae and slender gloeocystidia. In culture, dextrinoid fiber hyphae and papillate oil-bearing hyphae with clamp connections are characteristic. These and other features of the basidiocarp and culture serve in the characterization of this fungus, which is economically significant and widely distributed.

Sclerotial formation in Corticium olivascens and other hymenomycetes

Sclerotia ofCorticium olivascens are reported and described for the first time. Examples include sclerotia collected from a stump ofPinus virginiana in Greenbelt, Maryland, and those formed in several cultures originally developed from spores produced by basidiocarps. Among outstanding characteristics of basidiocarps ofC. olivascens are the greenish or olivaceous color of the hymenial surface, constant presence of clamp-connections, development of septate cystidia, and production of nonamyloid but dextrinoid basidiospores. Cultural characteristics are described, and the negative oxidase reaction is noted.C. olivascens is a highly distinctive fungus which requires further taxonomic attention. Sclerotia vonCorticium olivascens sind das erste Mal mitgeteilt und beschrieben. Beispiele betrifft Sclerotia, die vom Baumstumpf vonPinus virginiana in Greenbelt, Maryland gesammelt worden sind und diejenigen, die sich in mehreren Kulturen, ursprünglich von Sporen der Basidiocarpen entwickelt haben. Unter den besonderen Kennzeichen der Basidiocarpen vonC. olivascens sind die grünliche oder olive Farbe der Hymenialoberfläche, ständiges Vorkommen der Klammerverbindungen, Entwicklung septierter Cystidien und die Produktion von nicht-amyloiden, sondern dextrinoiden Basidiosporen. Kulturkennzeichen sind beschrieben und die negative Oxidasenreaktion ist erwähnt.C. olivascens ist ein hoch distinguierter Pilz, der eine weitere, taxonomische Aufmerksamkeit verlangt.

Delineations of forest fungi: Morphology and relationships of vararia

Vararia belongs in a group of hymenomycetes characterized by non-xanthochroic basidiocarps in which gloeocystidia are formed rather regularly. Basidia and gloeocystidia originate at a relatively deep level in a catahymenium or hyphidial hymenium; thus they are overgrown by continuing development of the hyphal elements. As a result, they may become deeply submerged in the structure of the basidiocarp, together with embedded basidiospores. Dichohyphidia are formed as dichotomously-branched structures of limited growth. Although commonly subulate, dichohyphidia may show a considerable range of form even within a single basidiocarp. In Melzers iodine reagent they commonly exhibit a dextrinoid reaction by becoming reddish brown. Hyphae of basidiocarps and cultures of some species have clamp-connections; those of other species lack clamps. Spores of the various species may be fusoid-ellipsoid, ellipsoid, globose, or cylindric, and may have either prominent or obscure amyloid ornamentation or may be apparently non-amyloid. Together with cultural characteristics such as the presence or absence of oedocephaloid conidiophores and various hyphal modifications, the hyphal and spore characteristics of the basidiocarp seem to present a potential basis for division ofVararia into several subgenera or generic segregates. The preceding considerations form the basis for a discussion of the position and relationships ofVararia within the Aphyllophorales.

Stereum Taxodii in Japan and Formosa

SUMMARYStereum taxodii, recently described from Taxodium distichum in the southern United States, occurs also on Cryptomeria japonica in Japan. Specimens from Torreya nucifera and Chamaecyparis for...

Taxonomy of the Pecan Scab Fungus

Pecan scab is caused by a fungus that for almost thirty years has been called Cladosporium effusum (Wint.) Demaree (1928). Originally, Winter (1885) described this species as Fusicladium effusum, but Demaree transferred it to Cladosporium primarily because the conidia may be produced in chains. The type specimen was collected on Carya alba, which is a synonym for either C. tomentosa Nutt. or C. ovata (Mill.) K. Koch. Three years later, Ellis and Langlois, in an article by Ellis and Everhart (1888), reported the occurrence of a similar fungus on living leaves of C. olivaeformis Nutt. [= C. illinoensis (Wang.) K. Koch]. Although they recognized that this new fungus was scarcely distinct from F. effusum, Ellis and Langlois distinguished it on the basis of its epiphyllous, maculicolous growth and darker hyphae, and named it F. caryigenum Ell. & Langl. Orton (1905) reported that F. caryigenum is identical with F. effusum Wint. Many years before C. effusum (Wint.) Demaree was used as the name for the pecan scab fungus, Berkeley and Curtis, in an article by Berkeley (1875), had described an altogether different fungus which they named C. effusum Berk. & Curt. The description was based on four specimens collected on hosts unrelated to Carya. These collections are now recognized as belonging in Cercospora (Chupp, 1953, pp. 356, 357). Nevertheless, C. effusum (Wint.) Demaree is a later homonym of C. effusum Berk. & Curt. and thus cannot be used as a name for the pecan scab fungus (cf. Lanjouw et al., International Code of Botanical Nomenclature, 1956, arts. 63, 64). This presents the necessity of selecting some other name for this fungus. The procedure necessarily involves re-examining the morphological relationships of the pecan scab organism. If it is found to be a Fusicladium, as originally presented, Winters name may be accepted. If Demaree is correct in believing it to be a Cladosporium, consideration may be given to making a new combination based on F. caryigenum. However, this would be feasible only if F. caryigenum is found to be conspecific with C. effusum (Wint.) Demaree.

STUDIES IN CONIOPHORA. I. THE BASIDIUM

Coniophora DC. ex Merat is a genus of the Thelephoraceae characterized by effused habit, essentially smooth hymenial surface, and smooth, colored spores that have peg-like apiculi. The genus has economic importance because of the wood-destroying propensities of some species, notably C. puteana (Schum. ex Fr.) Karst. There are probably not more than 20 or 30 species, but the taxonomy of the genus is in such state as to make an accurate estimate difficult. Burt (1917, 1926) included in Coniophora several species that have since (Rogers and Jackson, 1943) been excluded even though they have colored spores. The nature of the hyphae and the presence or absence of cystidia have been used along with spore-character as a basis for generic delineation. The basidium of Coniophora has essentially been ignored. Among many basidiomycetes, the basidium has been shown to have anatomical modifications that may provide clues to taxonomic relationships. Examples are the basidia of Trechispora and Galzinia (Rogers, 1944; Olive, 1954). Although somewhat less attention has been directed toward the basidia of many other genera among the more primitive homobasidiomycetes, some in addition to Trechispora and Galzinia may have basidia that depart considerably from the typical clavate development. Among these are Vararia, Aleurodiscus, Asterostroma, Tonentella, and some species of Corticium and Peniophora. Coniophora has a basidiocarp that lacks involved hyphal patterns. In this sense it may be said to resemble most of these other genera in having a corticioid type of fructification. In fungi with this simple kind of construction, the basidium is one of relatively few anatomical features that affords a possibility of fruitful study. In order to determine whether the basidia of Coniophora are distinctive, more than 100 specimens in the National Fungus Collections have been examined. The present condition of taxonomy in the genus does not permit entirely accurate determination of species in all instances, but that has relatively little importance in this study. Those specimens that may not be determined with absolute certainty are mostly in the complex centered around C. arida (Fr.) Karst.