Banksiamyces Katerinae

''Banksiamyces'' is a genus of fungi in the order Helotiales, with a tentative placement in the family Helotiaceae. The genus contains four species, which grow on the seed follicles of the dead infructescences or "cones" of various species of ''Banksia'', a genus in the plant family Proteaceae endemic to Australia. Fruit bodies of the fungus appear as small (typically less than 10 mm diameter), shallow dark cups on the follicles of the ''Banksia'' fruit. The edges of dry fruit bodies fold inwards, appearing like narrow slits. The first specimens of ''Banksiamyces'', known then as ''Tympanis toomansis'', were described in 1887. Specimens continued to be collected occasionally for almost 100 years before becoming examined more critically in the early 1980s, leading to the creation of a new genus to contain what was determined to be three distinct species, ''B. katerinae'', ''B. macrocarpus'', and ''B. toomansis''. A fourth species, ''B. maccannii'', was added in 1984.

Taxonomy

In 1887, English mycologists Miles Joseph Berkeley and Christopher Edmund Broome described a species of fungus they named ''Tympanis toomansis'', collected from dead infructescences ("cones") of ''Banksia'' growing on the banks of the Tooma River in southern New South Wales, Australia. Its generic placement was a result of its resemblance to ''Tympanis'', a genus in the family Helotiaceae of the Ascomycota.

Additional collections, then still believed to be ''T. toomansis'', were made from South Australia in 1952, again on dead cones of unspecified ''Banksia'', and also in 1956 on dead cones of ''Banksia marginata''. In 1957 and 1958, R. W. G. Dennis redescribed the species, and after consultation with Canadian mycologist James Walton Groves, who had earlier completed a monograph on the genus ''Tympanis'', transferred the taxon to the genus '' Encoelia'' (family Sclerotiniaceae). ''Encoelia'' species are small, tough, brownish discomycetes that typically grow in clusters on hardwood or woody substrates. Because the original collections were incomplete and certain microscopic features inadequately described, various collections made from Australia were presumed to be variations of the original 1887 collection.

In the 1980s, the availability of fresh specimens of the fungus—collected by Australian mycologist Bruce A. Fuhrer from the cones of ''Banksia spinulosa''—prompted Gordon Beaton and Gretna Weste to reexamine the previous collections. Various apparent and microscopic differences were found which suggested that three distinct species were represented in the collections, and further, the species differed enough from other ''Encoelia'' species to warrant the creation of a new genus, which Beaton and Weste named ''Banksiamyces''. The three ''Banksiamyces'' species they described in 1982 were the original ''B. toomansis'' (those initially named ''T. toomansis''), as well as ''B. macrocarpus'' and ''B. katerinae''. A fourth species, ''B. maccannii'', was added to the genus by the same authors in 1984. A 2006 study identified two additional taxa that did not quite meet the description for previously published species; these have been called ''Banksiamyces'' aff. ''macrocarpus'' and ''Banksiamyces'' aff. ''toomansis''. Some existing species were found on other banksia species, so evidence strengthened that the individual ''Banksiamyces'' fungi did not exclusively parasitize only one banksia species, a suggestion proposed by Beaton and Weste in 1982.

''Banksiamyces'' is classified in the Helotiaceae, a widespread but poorly known family of fungi, many species of which are saprobic on herbaceous or woody tissues. The placement in the Helotiaceae is tentative, and no molecular analysis has yet been performed that might clarify the phylogenetic relationships of ''Banksiamyces'' to other taxa in the Helotiales order. Based on physical similarity, Wen-Ying Zhuang included ''Banksiamyces'' under ''Encoelia'' in his 1998 study of the Encoelioideae subfamily of the Helotiaceae. He conceded, however, that he had not examined any specimens.

Description

The fruit bodies, or apothecia, of ''Banksiamyces'' species are cup-shaped receptacles borne on a stipe (stalk), colored dark brown to black with a dark grey center. When dry, the apothecia are covered with a whitish powder. The edges of the cup may be rolled inwards (especially when dry), or be twisted and somewhat flattened. Both the outermost tissue layer (the ''ectal excipulum'') and the tissue of the stalk are made of fungal cells with brown pigments that can be variously thick- or thin-walled, covered with small particles (''granules''), and spherical to ellipsoid. The middle tissue layer (the ''medullary excipulum'') of both the cup and the internal tissue layer (the ''medulla'') of the stalk contain a layer of tissue made of hyphae similar to the ectal excipulum. A second layer of tissue is made of hyphae that are translucent and gelatinous; this layer may be present in either the medullary excipulum, the medulla, or both.

The asci are elongated reproductive structures that bear ascospores, in groups of eight. ''Banksiamyces'' species have asci that are cylindrical to club-shaped, and contain a plug at their extreme tips that will absorb color when stained with iodine. The ascospores may be arranged in one or two rows (''uniseriate'' and ''biseriate'', respectively), or rarely, irregular. The ascospores are ellipsoid, translucent, have a slight curve and may be tapered; most ascospores contain two oil drops. When in the ascus, the ascospores are covered with a translucent mucilage that is highly refractive to light. Paraphyses are filamentous hyphal cells present in the fertile spore-bearing tissue, distributed amongst the asci. The free ends of the paraphyses fork and branch, combining with the tips of the asci to form a translucent to brown pigmented layer of tissue.

Species

Distribution of ''Banksia'' species (the host of ''Banksiamyces''), grouped into western species, ''series_
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*_George_Series_(1920–1995),_English_physicist
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