Candida metrosideripro tempore sp. nov. andCandida ohialehuaepro tempore sp. nov., two antifungal-resistant yeasts associated withMetrosideros polymorphaflowers in Hawaii

Abstract

Flowers produce an array of nutrient-rich exudates in which microbes can thrive, making them hotspots for microbial abundance and diversity. During a diversity study of yeasts inhabiting the flowers ofMetrosideros polymorpha(Myrtaceae) in the Hawai'i Volcanoes National Park (HI, USA), five isolates were found to represent two novel species. Morphological and physiological characterization, and sequence analysis of the small subunit ribosomal RNA (rRNA) genes, the D1/D2 domains of the large subunit rRNA genes, the internal transcribed spacer (ITS) regions, and the genes encoding the largest and second largest subunits of the RNA polymerase II (RPB1andRPB2, respectively), classified both species in the familyMetschnikowiaceae, and we propose the namesCandida metrosideripro tempore sp. nov. (JK22(T)= CBS 16091 = MUCL 57821) andCandida ohialehuaepro tempore sp. nov. (JK58.2(T)= CBS 16092 = MUCL 57822) for such new taxa. Both novelCandidaspecies form a well-supported subclade in theMetschnikowiaceaecontaining species associated with insects, flowers, and a few species of clinical importance. The ascosporic state of the novel species was not observed. The two novel yeast species showed elevated minimum inhibitory concentrations to the antifungal drug amphotericin B (>4 mu g/mL). The ecology and phylogenetic relationships ofC.metrosideriandC.ohialehuaeare also discussed.