Conidium development in the Hyalorhinocladiella anamorphs of Ceratocystiopsis minuta-bicolor and Ophiostoma minus

Abstract

The genus Hyalorhinocladiella was characterized by its simple conidiophores with conidiogenous cells that proliferate sympodially. However, recent studies revealed that the Hyalorhinocladiella anamorph of Ophiostoma ips has annellidic conidium development. The aim of this study was to determine whether other species in the genus share this characteristic. Conidium development was examined in the type species, Hyalorhinocladiella minuta-bicolor, and in the Hyalorhinocladiella anamorph of Ophiostoma minus. Light and fluorescence microscopy indicated that conidia developed by sympodial proliferation. In contrast, scanning and transmission electron microscopy revealed distinct annellations on the conidiogenous cells. Conidium development in Hyalorhinocladiella is therefore annellidic, and the appearance of sympodial development results from displacement of the long axis of the conidiogenous cell through percurrent proliferation. The circumscription of the genus Hyalorhinocladiella is therefore revised to include annellidic conidium development. Keywords: Hyalorhinocladiella, Ophiostoma, sympodial, annellidic, conidium development.