Calochlaena, a New Genus of Dicksonioid Ferns

The genus Culcita C. Presl contains several species of dicksonioid ferns. Before 1922 these species were included in Balantium Kaulf., then regarded as typified by Balantium culcita (L'Her.) Kaulf. (now known as Culcita macrocarpa C. Presl). Maxon (1922) demonstrated that Balantium should be typified by B. auricomum Kaulf., a synonym of Dicksonia arborescens L'Her., the type of Dicksonia. Balantium is thus a synonym of Dicksonia. Culcita is the correct name for the segregate genus typified by Dicksonia culcita L'Her. ( = Balantium culcita). Culcita macrocarpa is found in the Azores, Madeira, Spain, and Portugal (Fraser-Jenkins & Lainz, 1983). It is closely related to C. coniifolia (Hook.) Maxon, of tropical America. Also included in Culcita are several species from Australasia and the Philippines. This latter group of species was first associated with Balantium when Diels (1899) and Copeland (1908, 1909) added the species Balantium stramineum (Labill.) Diels, Balantium dubium (R. Br.) Copel., and B. javanicum (Blume) Copel. to that genus. Maxon (1922) recognized eight species of Culcita. Differences in soral characters led him to create a new subgenus Calochlaena for two of these species, the Australian C. dubia (R. Br.) Maxon and an alleged new species from Fiji, C. blepharodes Maxon, which we believe is a synonym of C. dubia. Although Maxon regarded such species as C. straminea and C. javanica as typical Culcita, not Calochlaena, more recent authors have enlarged subg. Calochlaena to include all of the Australasian species (Copeland, 1947; Holttum & Sen, 1961; Holttum, 1963, 1964). These authors apparently were not aware that this was not Maxon's original subgeneric concept. Significant differences between members of the two subgenera of Culcita have frequently been reported. These include differences in anatomy (Davie, 1918; Holttum, 1963; Holttum & Sen, 1961), in spore morphology (Gastony, 1981), and in chromosome number (Manton in Holttum & Sen, 1961; Manton in Holttum, 1963; Roy & Holttum, 1965). These have prompted suggestions that the genus may need to be divided (Holttum, 1963; Roy & Holttum, 1965; Gastony, 1981; Tryon & Tryon, 1982). The need for taxonomic reassessment of Culcita became evident to us in the course of an anatomical survey of the tree ferns (see White, 1984). In the present paper we summarize evidence for the generic distinctness of the two groups and erect a new genus for the species of subg. Calochlaena. Culcita thus becomes restricted to the two species C. macrocarpa and C. coniifolia.