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Cucurbitaria elongata
Nomenclature
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Family: CucurbitariaceaeGenus: Cucurbitaria
SUMMARY
Anamorph: Camarosporium sp. fide Mirza (1968); possibly C. robiniae (Westend.) Sacc. Conidiomata 150-200 µm diam, ± spherical, black, smooth or slightly verrucose, sometimes hairy, the ostiole conspicuous and minutely papillate, uniloculate, erupment and sometimes becoming ± superficial on the exposed basal stroma. Conidiophores absent. Conidiogenous cells not seen in material available. Conidia 15-20.5 x 6.5-8 x 5-6 µm, cylindric-ellipsoidal, bilaterally flattened, the apices rounded, golden to dark brown, with 3-4 (rarely to 7) transverse septa with usually two cells (mostly either the end cells or the median cells) subdivided by a frequently strongly oblique longitudinal septum, the septa not constricted; mucous sheath not seen.
Teleomorph: Stroma subperidermal, sometimes extensive, composed of intertwined dark hyphae, bearing clusters of uniloculate conidiomata and ascomata which are erumpent through longitudinal cracks in the bark. Ascomata 250-300 µm diam, globose to turbinate, often flattened on top, black, carbonaceous, minutely verrucose, with a conspicuous sunken ostiole. Peridium with outer layer of dark brown strongly melanized textura angularis with cells to 15 µm diam, merging into an inner region of smaller ± hyaline cells, the ascomatal cavity occupying most of the ascostroma. Interascal tissue copious, of cellular pseudoparaphyses ca 2 µm diam. Asci 148-175 x 13.5-16 µm, cylindrical, short-stalked, thick-walled and fissitunicate, the apex rounded, with a distinct apical invagination in the inner wall, 8-spored. Ascospores 19.5-24 x 9.5-11 µm, reddish brown, muriform, the apices usually rounded to almost truncate, rarely acute, mucous sheath not seen, constricted at the ± median primary septum with the upper part equal to the lower or slightly greater in width, with 4-5 secondary transverse septa and usually a single longitudinal septum which does not extend the whole length of the spore, the septa sometimes irregular in orientation.
This is doubtfully distinct from other species on Fabaceae such as C. laburni, but is provisionally accepted as a species associated with Robinia. It has been treated as plurivorous in the past (e.g. Welch, 1926; Sivanesan, 1984), and some GB records may refer to similar fungi on unrelated hosts. GB material seen on Robinia identified as this species includes a Camarosporium anamorph which may not be conspecific; the conidia have fewer septa than those from holomorphic material studied from central Europe. It is very similar to the fungus illustrated as C. propinquum by Sutton (1980). GB material on Prunus twigs identified as this species (IMI 76959, K) may be referable to Teichospora, but the collection is too sparse for a firm placement. GB material collected from wooden rails identified as C. elongata var. simplex is Lophiostoma compressum