Hymenophyllum fucoides (Sw.) Sw., J. Bot. (Schrader) 1800

Kessler, Michael & Smith, Alan R., 2017, Prodromus of a fern flora for Bolivia. X. Hymenophyllaceae, Phytotaxa 328 (3), pp. 201-226 : 208

Hymenophyllum fucoides (Sw.) Sw., J. Bot. (Schrader) 1800 (2): 99. 1801.

Range: —Antilles; southern Mexico to Venezuela and Bolivia (CO, LP, SC); southeastern Brazil.

Ecology: —Very common and conspicuous; epiphytic, rarely terrestrial (especially among mosses) or on rock walls in humid forests; (900–)1700–3600(–4100) m.

Notes: —This is the most common species of subg. Hymenophyllum in Bolivia, and an extremely variable taxon that may comprise more than one species. Plants vary in involucral shape (from as long as broad to 3 times longer than broad), margin (entire to strongly dentate), number per pinnae (1–10), and overall size, as well as petiole thickness. Four varieties were recognized in Peru by Tryon & Stolze (1989), including, e.g., var. pedicellatum (Klotzsch) Hieron. , with strongly toothed involucral apices, and var. chachapoyense Stolze , with undulate segment wings. These are now known to be genetically distinct (M. Lehnert, pers. comm.) so that they may better be treated at species level. However, only typical H. fucoides has so far been found in Bolivia, although H. calodictyon Bosch , from Ecuador and Peru, may occur in Bolivia. It differs from H. fucoides by having partially winged petioles. Even without these distinct variants, Bolivian specimens differ markedly in overall size, width and arrangement of the segments, and number, size, and margin development (entire to serrate) of the involucres. In addition, sterile leaves tend to look quite different from fertile ones, having more spreading and equilateral pinnae, versus the more ascending and acroscopically better developed pinnae of fertile leaves.