The present study represents a taxonomic revision of the Pheidole sikorae species group from Madagascar. Forty-four members of this group are recognised and described, and an illustrated identification key to this group is also presented. One species is raised to species level: P. litigiosa Forel, 1892 stat. nov.Pheidole veteratrix angustinoda Forel, 1892 syn. nov. is proposed as a junior synonym of Pheidole veteratrix Forel, 1891. Worker castes are also described and lectotypes designated for P. litigiosa Forel, 1892, P. sikorae Forel, 1891, and P. veteratrix Forel, 1891. The following 41 new species are described: P. alinasp. nov., P. ambohimangasp. nov., P. analavelonasp. nov., P. andohahelasp. nov., P. anomalasp. nov., P. anosyennesp. nov., P. antranohofasp. nov., P. beankasp. nov., P. befotakasp. nov., P. dasossp. nov., P. flavominutasp. nov., P. gracilissp. nov., P. habokasp. nov., P. havoanasp. nov., P. hazosp. nov., P. itremosp. nov., P. joffrevillesp. nov., P. kelysp. nov., P. lavasoasp. nov., P. mahamavosp. nov., P. maintysp. nov., P. mamiratrasp. nov., P. mananteninasp. nov., P. masoandrosp. nov., P. mavohavoanasp. nov., P. midongysp. nov., P. mikrossp. nov., P. mivorysp. nov., P. nitidobrunasp. nov., P. parvulasp. nov., P. parvulogibbasp. nov., P. reniranosp. nov., P. savasp. nov., P. sofiasp. nov., P. sparsasp. nov., P. tamponysp. nov., P. trichotossp. nov., P. tsaravonianasp. nov., P. vadumsp. nov., P. volontanysp. nov., and P. vonysp. nov. At present, there are 109 valid species and subspecies of Pheidole known from Madagascar, but this number is expected to increase with upcoming taxonomic revisions of the species groups not revised in this study.
