Synonymy Amongst the Arbuscular Mycorrhizal Fungi: Glomus claroideum, G. maculosum, G. multisubstenum and G. fistulosum

Abstract Ex-type material ofGlomus fistulosumwas re-established in pot culture and differences from the description in the protologue noted. Type specimens and other cultures from Europe, and North and South America showed the original species description was incorrect. The species is re-described from pot cultured specimens. The holotype ofGlomus claroideumwas also examined. The two species were morphologically identical. This was confirmed by comparisons with other specimens ofG. claroideum.One culture, used in the protologue, but not designated as a paratype, had smaller spores than those from otherG. fistulosumorG. claroideumcultures, but could not otherwise be separated. They are therefore synonymized. Type material ofGlomus maculosumand specimens ofGlomus manihotisfrom Colombia were studied. The latter came from a heavily parasitized pot culture, and its spores possessed the maculiferous ‘ornamentation’ that supposedly characterized the former. Similar structures were noted in the isotype ofG. claroideum.The feature is probably environmentally induced and should not be used as a taxonomic characteristic. The conclusion is drawn thatGlomus maculosumshould also be synonymized withG. claroideum. Glomus multisubstensumis considered from its protologue, and this too should be synonymized withG. claroideum.An epitype is defined to aid in the circumscription ofG. claroideum.Less comprehensive comparisons were also made with other similar species,G. albidum, G. przelewicense, G. lamellosum, G. pustulatumandG. diaphanum.It is concluded thatG. lamellosumis inadequately defined, and its validity as a species needs clarification. It is also suggested thatGlomus albidumandG. przelewicensemay be conspecific.

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