What happened to Acaulospora gerdemannii, Ac. appendicula, Glomus leptotichum and Gl. fecundisporum?
Nicolson & Schenck (1979) published the name Acaulospora gerdemannii.
Schenck & Smith (1982) published two names, Glomus fecundisporum and Glomus leptotichum.
Schenck et al. (1984) published the name Acaulospora appendicula.
Morton et al. (1997) combined Acaulospora gerdemannii and Acaulospora appendicula as Acaulospora gerdemannii. At the same time, they combined Glomus leptotichum and Glomus fecundisporum as Glomus leptotichum.
Morton & Redecker (2001) combined the resultant Glomus leptotichum and Acaulospora gerdemannii into a new genus, producing Archaeospora leptoticha (created from the combination of the former Acaulospora gerdemannii, Acaulospora appendicula, Glomus fecundisporum and Glomus leptotichum).
Spain et al. (2006) chose a different path, ignoring the position of the former Glomus spp., created a new genus, Appendicispora, and placed the former Acaulospora appendicula and Acaulospora gerdemannii into this new genus as Appendicispora appendicula and Appendicispora jimgerdemannii, respectively.
More or less simultaneously, Walker et al. (2007a) created (because Archaeospora was paraphyletic) a new genus, Ambispora, based on a new species, Ambispora fennica. They accepted the view of Morton & Redecker (2001) that the former Acaulospora gerdemannii and Acaulospora appendicula, combined with the former Glomus leptotichum and Glomus fecundisporum, were conspecific (i.e., represent Archaeospora leptoticha) and moved this composite as a species into the genus Ambispora, as Ambispora leptoticha.
The genus Appendicispora (Spain et al. 2006) was published slightly earlier than Ambispora (Walker et al. 2007a), so Walker et al. 2007b wrote a note to that effect, changing all their Ambispora species into Appendicispora based on the separation of species as given in the Appendicispora protologue.
It was then realised that Appendicispora was not a valid name under the rules of the Botanical Code, and it consequently had to be rejected completely, and the species concerned were moved (back) into Ambispora (Walker 2008). However, this time the original names were followed as valid separate species (as in Spain et al. 2006), rather than the combined names as in Morton & Redecker 2001, with the consequence that the current names are as follows (the epithet change to the former Acaulospora gerdemannii to jimgerdeamannii is necessary because the former Glomus gerdemannii (Ambispora gerdemannii) has priority:
Glomus fecundisporum became Ambispora fecundispora
Glomus leptotichum became Ambispora leptoticha
Acaulospora appendicula became Ambispora appendicula
Acaulospora gerdemannii became Ambispora jimgerdemannii