Ambrosiella in Taiwan including one new species

Ambrosiella species in the latest definition are tightly associated with ambrosia beetles in genera Anisandrus, Cnestus, and Xylosandrus within the tribe Xyleborini characterized by a mesothoracic mycangium. Eccoptopterus and Hadrodemius are another two xyleborine genera possessing mesothoracic mycangium, but their symbiotic fungi are unknown. A survey of Ambrosiella s.s. in Taiwan revealed five species, including one new species, A. catenulata, and indicated that members of Eccoptopterus and Hadrodemius are also associated with Ambrosiella s.s. It corroborates a previous hypothesis that Ambrosiella s.s. species are exclusively associated with ambrosia beetles having mesothoracic mycangium. The association appears asymmetrical: a single Ambrosiella species can be carried by multiple species of beetles, while each beetle species associates with only one Ambrosiella species. Descriptions and illustrations of species obtained in this study are provided. Identification is based on morphological and molecular analyses.