The moss Barbula agraria Hedw., a discordant element in the genus Barbula, is recognized as distinct at the generic level by upgrading the monotypic Barbula sect. Hyophiladelphus C. Mull. Cladistic analysis supports a removal to the subfamily Pottioideae wherein Hyophiladelphus is related to one of two circum- Tethyan groups of genera. This study details the several necessary methodological steps for reclassifying this problematic species. Barbula agraria Hedw. is a small, nearly stemless moss endemic to islands and mainland shores of the Caribbean area. It has been described, discussed, and illustrated by Bartram (1949), Breen (1963), Crum and Steere (1957), Steere (1938), Crum and Anderson (1981), and Zander (1979, 1993, 1994). It is particularly common in the West Indies, whence I have seen specimens from Barbados, Cuba, Do- minican Republic, Guadaloupe, Haiti, Jamaica, Martinique, Puerto Rico and the Virgin Islands. It is one of a distinctive group of Pottiaceae, including the essentially Caribbean species Luisierella barbula (Schwaegr.) Steere, Quaesticula navicularis (Mitt.) Zand., and Plaubelia sprengelii (Schwaegr.) Zand., that have a morphology apparently adapted to a shared sun-drenched, dry habitat of tropical and subtropical islands and the shores of nearby mainlands. That morphology includes a rosulate, short-stemmed habit, broad leaves with plane or incurved margins, ventrally bulging upper laminal cells, and papillae small or entirely absent. In the genus Barbula (authorities of the supraspe- cific taxa throughout are according to Zander 1993), B. agraria has long been recognized as incongruous because of its broadly ellipical or spathulate leaves, but its two costal stereid bands have not, in the past, been taxonomically acceptable in the Tortula rela- tionship, which is characterized by such leaves but with a single band. C. Miiller (1849) placed B. agrar- ia in Barbula sect. Hyophiladelphus C. Mull., to- gether, significantly, with Barbula spathulata Dozy & Molkenb. (a synonym of Hyophila involuta (Hook.) Jaeg.), citing as distinctive the involute, more or less spathulate leaves, and both basal and upper laminal cells small and lacking papillae. Zander (1979) raised Miiller's section to the subgenus level, and noted a clear resemblance to Luisierella barbula through the similar strongly colliculate adaxial laminal surface and nearly smooth abaxial surface. Steere (1938) placed B. agraria in its own group, B. sect. Agrariae, saying of the species that it ap- proaches Barbula in the structure of its costa, but on the basis of leaf-shape it is frequently placed in Tortula. It is sufficiently distinct from both genera, however, to justify, perhaps, the eventual erection of a new genus. A cladistic analysis of the family Pottiaceae at the genus level (Zander 1993) demonstrated the exis- tence of a lineage of taxa to B. agraria in morphology, especially in the leaves often tubulose when dry, leaf margins plane or incurved or invo- lute, and upper laminal cells ventrally bulging. The leaf shape was commonly elliptical or spathulate, but also occasionally lanceolate, and the number of stereid bands was either one or two. Included were the 18 genera Aloina, Aloinella, Crossidium, Gan- guleea, Globulinella, Hymenostyliella, Hyophila, Hypodontium, Luisierella, Molendoa, Plaubelia, Pterygoneurum, Quaesticula, Stegonia, Teniolo- phora, Weisiopsis, Weissia, and Weissiodicranum. The group occurred either as comprising the base of the Pottioideae subclade (Zander 1993, pp. 41, 42) when analyzed with Timmia or Ptychomitrium as outgroups, or as a separate branch of the Pot- tioideae subclade (1993, pp. 40, 46) with Polytri- chum as outgroup or Timmiella as functional out- group. Viewing the last cladogram of the four as best, Zander (1993) recognized the group as the Hy- ophileae.