Raffaelea spp. from five ambrosia beetles in the genera Xyleborinus and Cyclorhipidion (Coleoptera: Curcurlionidae: Scolytinae: Xyleborini)

Abstract

<p>Five undescribed species of Raffaelea (Ophiostomatales), as well as Raffaelea sulphurea, were isolated and illustrated from the ambrosia beetle tribe Xyleborini: Raffaelea sulphurea and Raffaelea sp. A from Xyleborinus saxeseni; Raffaelea sp. B and Raffaelea sp. C from Xyleborinus attenuatus; Raffaelea sp. D from Xyleborinus gracilis; Raffaelea sp. F from Cyclorhipidion bodoanum; and Raffaelea sp. G from C. pelliculosum.</p> <p>Each fungal symbiont was isolated from a single beetle host species or its galleries and characterized by culture morphology and DNA sequencing. Analysis of of 18S rDNA and translocation elongation factor sequences of five undescribed symbionts (Raffaelea sulphurea, Raffaelea sp. B, Raffaelea sp. D, Raffaelea sp. F, and Raffaelea sp. G) supported the hypothesis that Dryadomyces is a genus distinct from Raffaelea spp. In culture, Dryadomyces spp. produce fast-growing, red-brown mycelia with no yeast-like budding, unlike typical Raffaelea spp. Raffaelea montetyi, R. quercivora, R. quercus-mongolicae and Raffaelea sp. D formed another group sister to the Dryadomyces subclade. The members of this R. montetyi subclade produce yeasty, mucoid colonies and hyaline mycelia similar to R. lauricola. Raffaelea sp. A and Raffaelea sp. C were closely related to R. canadensis. This R. canadensis complex was placed among typical Raffaelea spp. in phylogenetic analysis. Thus, both molecular and phenotypic characteristics suggest that ambrosia beetle symbionts within the Ophiostomatales are not monophyletic.</p>