The extreme conditions of life in Antarctica pose challenges to many organisms. Bryophytes comprise the main vegetation of the continent and they endure many adversities, thriving in an environment hostile to most living organisms. Mosses are known to exhibit phenotypic plasticity, due to genotypic heterogeneity, environmental influences, or a combination of both. We investigated morphological diversity and its possible relationship with genetic diversity in the Antarctic moss, Roaldia revoluta, and also if the geographic distribution of morphotypes was related with environmental variables. We obtained 49 samples from Antarctica, including King George Island (K), James Ross Island (J), and several locations in the Antarctic Peninsula (P), representing most of the habitats where this species is found. A principal component analysis (PCA) was performed using quantitative measures of gametophytic morphological characters. For molecular analyses, we used DNA sequences of five molecular markers obtained from 29 specimens. Canonical correspondence analysis (CCA) was carried out to compare morphological diversity with environmental variables. Our data support the existence of two morphotypes of R. revoluta, morphotype A (apiculate and ovate leaves), more frequent in K, and morphotype B (acuminate and more oblong leaves), more common in J. Both morphotypes were present in P. The distinct morphotypes could not be related with genetic heterogeneity, since no sequence differences were found in any of the selected markers, supporting the morphological distinction being explained by environmental factors. The results from CCA supported a relationship between the observed morphological variation and the local environmental characteristics of wind speed and minimum temperature.