Embryo Development in Extremophiles are the developmental modes responsible for convergent adult phenotypes examined in a comparative approach (but see for example [51]). Our results clearly demonstrate that convergent shifts in phenotypic traits among closely related taxa are not always achieved by convergent processes during embryo develop- ment, but rather, that even sister taxa can evolve taxon-specific, alternative developmental modes to achieve replicated phenotypes [102]. Our study supports the view forwarded by Arendt & Reznick [52], who suggested that scientists should refrain from making the distinction between parallel and convergent evolution, because even closely related taxa can evolve replicated phenotypes via alternative developmental and genetic mechanisms, while distantly related taxa sometimes evolve replicated phenotypes via the same developmental and genetic mechanisms (reviewed in [52]; but see also [102]). the University of Oklahoma (AUS- IACUC approved protocols: R06–026 and R09–023). Supporting Information Figure S1 Lip protuberances of the sulphur molly (P. sulphuraria). Female, dorsal view. Arrows indicate lip protu- berances. Scale bar = 1 mm. (TIF) Acknowledgments We would like to thank L. Arias-Rodriguez, T. J. Colston, F. J. Garc´ıa de Le o´n, and M. Tobler for help during the collections in the field. The Mexican Government and the Municipal of Tacotalpa kindly provided permits for the work in Mexico. 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