CONTRIBUTIONS TO OUR KNOWLEDGE OF AMBROSIA FUNGI. I. ASCOIDEA HYLECOETI SP. NOV. (ASCOMYCETES)

Abstract

BATRA, LEKH R. (U. Kansas, Lawrence), and HELENE FRANCKE-GROSMANN. Contributions to our knowledge of ambrosia fungi. I. Ascoidea hylecoeti sp. nov. (Ascomycetes). Amer. Jour. Bot. 48(6): 453-456. Illus. 1961.-The genus Ascoidea Bref. & Lindau in Brefeld (1891) belongs to the family Ascoideaceae (Endomycetales, Hemiascomycetidae). Ascoidea differs from all other ascomycetes by its possession of characteristic multispored asci which proliferate, the newer asci being formed through the collar-like wall remnants of older asci. Ascogenous hyphae are absent. The present fungus differs in many ways from the type and the only species of the genus, A. rubescens Bref. & Lindau. Ascoidea hylecoeti reproduces asexually by chlamydospores. The asci are conical and many spored. They are aggregated in thick clusters of 50-200 individual asci. The number of ascospores per ascus is much larger than that of A. rubescens and their size is much smaller. Ascoidea hylecoeti is known to occur only in association with the genus Hylecoetus, one of the ambrosia beetles. AMBROSIA fungi are a group of fungi which live symbiotically with some genera of insects. Most of these fungi live saprophytically on plant and in. sect material. although some may have a rather complex and parasitic role together with the insect partner in the formation of so-called ambrosia galls on some plants. Generally, these fungi serve as a major source of food for the developing larvae. Ambrosia fungi are predominantly ectosymbiotes. They are characterized by having mucilaginous spores and fragrant colonies when grown on common laboratory media or when observed in the field. Some of these fungi cause blue staining of logged timber. resulting in heavy economic losses in some parts of the world. These fungi usually overwinter in the form of oidia, thick-walled chlamydospores, or dried, shiny. and mucilaginous crusts of ascospores. The female ambrosia beetles carry the fungi in special structures and the inocula are deposited during oviposition along with the eggs (FranckeGrosmann 1952, 1956, 1957). Taxonomically, most of the ambrosia fungi belong to the Endomycetales, Ophiostomatales and other ascomycetous orders and Fungi Imperfecti (Batra, 1959). Some unidentified Basidiomycetes have also been isolated by the present authors, although no Phycomycetes have so far been observed. Ascolidea hylecoeti was isolated during our studies of symbiotic relationships between ambrosia fungi and ambrosia beetles. Like many other such fungi, this fungus lives as an ectosymbiote and is