Phylogenetic and physiological traits of oomycetes originally identified as Lagenidium giganteum from fly and mosquito larvae

Abstract

ABSTRACTWe studied phylogenetic and taxonomic features of isolates identified as Lagenidium giganteum recovered from six different species of mosquito larvae. The isolates grew vigorously at 25 C, moderately at 30 C, and not at all at 37 C and developed submerged, white colonies with few short, hyaline, aerial hyphae. Cultures displayed phenotypic plasticity, with broad, hyaline hyphae strongly constricted at septa that developed oval, spherical, or amorphous segments. These developed into sporangia producing one or two exit tubes, from which evanescent gelatinous vesicles containing zoospores developed. Three isolates developed oogonia consistent with features previously described for L. giganteum. Phylogenetic analysis of nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS = ITS) and cytochrome c oxidase subunit II (COXII) sequences of L. giganteum consistently grouped into eight clusters. Four of the investigated isolates grouped with sequences of an unnamed Lagenidium species infecting nematodes. Based on phenotypic and phylogenetic data, we describe the latter isolates as L. juracyae, sp. nov. In addition, we also investigated a species of Paralagenidium from a dog with lagenidiosis and describe it as new, Paralagenidium ajellopsis, sp. nov.