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The morphospecies Fusarium dimerum, known only from its anamorph, comprises at least 12 phylogenetically distinct species. Analyses of the large subunit ribosomal DNA (LSU rDNA) show they are taxa of the Nectriaceae (Hypocreales), related to F. domesticumand form a phylogenetically distinct clade within Fusarium. Fusarium dimerum, for which no herbarium material could be located, is characterized by macroconidia with a single, median septum, according to the original description and illustration. Fusarium lunatum(= F. dimerumvar. violaceum) forms similar but longer macroconidia and purple, catenate or clustered chlamydospores. Fusarium delphinoidessp. nov., F. biseptatumsp. nov., F. penzigiisp. nov., F. nectrioidescomb. nov. (= F. dimerumvar. nectrioides) and two unnamed Fusariumspp. produce macroconidia with mostly two or rarely three septa. The name F. dimerum, which originally was applied to a fungus from a citron, is used for a taxon including isolates causing infections in immunocompetent and immunocompromised patients. Fusarium nectrioides, F. delphinoides, F. penzigiiand F. biseptatumare known from soil and dead plant substrata or rarely as agents of trauma-related eye infections of humans. Fusarium lunatumis an inhabitant of the cladodes of species within the cactus genera Opuntiaand Gymnocalycium. Its unnamed closest sister taxon, which also forms 1-septate macroconidia and purple, clustered chlamydospores, was isolated from a human sinus. Fusarium delphinoidesis a pathogen of the cactus-like African species Hoodia gordonii(Apocynaceae). Phylogenetic analyses based on combined sequences of the internal transcribed spacer region, LSU rDNA and partial sequences of the elongation factor 1-alpha and beta-tubulin genes identified a clade of several species producing predominately 2-septate macroconidia as the reciprocally monophyletic sister of F. dimerum. The basal sister group of the two aforementioned clades includes Fusarium lunatumand two undescribed species, all of which form 1-septate macroconidia.

ABSTRACTPhaeohyphomycosis is an infection caused by brown to black fungi presenting in tissue sections as dark walled septate hyphae, dark walled yeast, or both. Disseminated phaeohyphomycosis in reptiles has rarely been reported in the literature. An adult Galapagos tortoise, Geochelone nigra, presented with unilateral ocular lesions consisting of buphthalmia and a posterior chamber density. Clinical progression, diagnostics, and therapeutics are discussed. Diagnosis of phaeohyphomycosis was made on histopathology of the enucleated eye. Eventual euthanasia and necropsy revealed widespread granulomatous inflammation with fungal invasion. Dissemination was likely hematogenous. Culture and molecular analyses determined the etiologic agent to be an Exophialaspecies not previously seen. A species name has not been determined for this fungus.