Submitted to: Mycologia
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/23/2004
Publication Date: 9/1/2004
Citation: Delalibera, I., Hajek, A.E., Humber, R.A. 2004. Neozygites tanajoae sp. nov., a pathogen of the cassava green mite. Mycologia. 96(5):1002-1009. Interpretive Summary: Cassava green mite (CGM), MONONYCHELLUS TANAJOA, is a significant pest of cassava in Brazil and West Africa where this host plant is the main subsistence crop. CGM is often infected in Brazil by a fungal pathogen that differs little in morphology from NEOZYGITES FLORIDANA, a major fungal pathogen affecting many plant-feeding mite species worldwide. This fungus has also been introduced intentionally in Africa to control CGM, and there appears to be an indigenous population of a NEOZYGITES in West Africa that also affects CGM and seems very similar to Brazilian CGM fungus. Despite the similarities to N. FLORIDANA, the Brazilian fungus shows a high specificity for CGM, has markedly different nutritional and physical requirements for its growth in culture and preservation, a much lower tolerance for cool temperatures, and differences in genomic sequences. Accordingly, the Brazilian/African CGM fungus was determined to be a new species that is described here as NEOZYGITES TANAJOAE. This paper clarifies the status of N. FLORIDANA as a complex of morphologically similar taxonomic species from which other new species might still be identified and establishes new taxonomic criteria to be used to distinguish new species in NEOZYGITES.
Technical Abstract: The fungal pathogen NEOZYGITES TANAJOAE Delalibera Jr., Humber & Hajek sp. nov. (Zygomycetes: Entomophthorales) is being used in Africa as a biological control agent against the introduced cassava green mite (CGM), MONONYCHELLUS TANAJOA (Bondar) (acari: Tetranychidae). This fungus is specific to CGM and has been referred to as N. FLORIDANA (Weiser & Muma) Remaud. & Keller, a common pathogen of many tetranychid mites. In the present study N. TANAJOAE is investigated at the morphological and molecular levels and physiological attributes of N. TANAJOAE and N. FLORIDANA are compared. Morphological observations of N. TANAJOAE isolates generally correspond to N. FLORIDANA and to other mite pathogenic species of NEOZYGITES. However, this fungus readily can be distinguished from N. FLORIDANA based on 18S rDNA sequences, host ranges, nutritional requirements for growth in vitro, tolerances to cold (4 C) and abilities to withstand specific cryopreservation techniques. N. TANAJOAE isolates from Brazil and Africa have identical 18S rDNA sequences but they presented 5.7 and 9/94% pairwise distance from N. Floridana isolates. N. TANAJOAE proved to differ sufficiently from other mite-pathogenic fungi referred to as N. FLORIDANA to justify the description of a new species.