Pecluma M.G.Price, Amer. Fern J.

Smith, Alan R., Kessler, Michael, León, Blanca, Almeida, Thaís Elias, Jiménez-Pérez, Iván & Lehnert, Marcus, 2018, Prodromus of a fern flora for Bolivia. XL. Polypodiaceae, Phytotaxa 354 (1), pp. 448-450 : 448-450

Pecluma M.G.Price, Amer. Fern J. 73(4): 109. 1983.

Pecluma is entirely neotropical and was segregated from Polypodium by Price (1983). Currently ca. 45 species are known, with probably a dozen others currently considered as Polypodium spp. , likely to be transferred (A.R. Smith unpubl. data). Evans (1969) monographed Pecluma (within Polypodium ) and considered it a discrete clade; since then, Kessler & Smith (2005) and Salino (1998) recognized additional species, and the genus has been given a revised circumscription by Assis et al. (2016). In this last work, several Mexican and Mesoamerican species included previously in Polypodium (e.g., by Mickel & Smith 2004) were transferred to Pecluma . With this new definition, Pecluma was said to comprise 44 species, but it seems likely to grow with the addition of other, unsampled (by Assis et al. 2016) species, especially in Mexico and Mesoamerica. South America in general, and the Andes, Bolivia, and Brazil in particular, are major centers of diversity in the genus. Twenty species and several varieties are known from Bolivia, with one, P. perpinnata , being recently described ( Kessler & Smith 2005). New combinations have also made by several workers for others, building on the initial revision by Evans (1969).

Pecluma differs from Polypodium and Serpocaulon , in which it has historically been included or associated, by the combination of short, unbranched rhizomes; sometimes proliferous roots; nonclathrate, basally attached rhizome scales; round, generally terete (not grooved), dark petioles; pectinate blades with relatively narrow pinnae; and predominantly free veins. Most of these characters may be found singly or sporadically in some species of Serpocaulon . Pecluma also resembles some species of Terpsichore , and species once placed in the grammitid genus Ctenopteris ( Copeland 1956) , but the latter differs by its long (0.5–2 mm) whitish or pale reddish hairs (most easily seen on the petioles), lack of pronounced phyllopodia, and by having green, trilete spores. Dried specimens of Pecluma typically have a strongly arched rachis that makes it difficult to flatten them out. Pecluma is adapted to desiccation, the pinnae curling during drought. Apogamy and polyploidy are both known in the genus ( Evans 1969), and the species limits are unclear in certain species groups.

The following characters are useful for distinguishing Bolivian species: rachis color (brown vs. black); frond size; rachis scales (present vs. absent); blade dissection (pinnatisect or pinnae free from adjacent pinnae, adnate to rachis); blade base (gradually vs. abruptly reduced proximally); number of reduced pinna pairs; pinna length and width, pinna aspect (spreading vs. ascending); pinna margins (entire vs. sinuate or crenate); blade apex (determinate or seemingly indeterminate, fronds never completely uncoiling); abaxial laminar hairs (between veins present or absent); venation (veins free vs. partly anastomosing), and vein forking (1–3-forked); minute, erect hairs in a patch surrounding sori (vs. such hairs absent).

Phylogenetic analyses by Schneider et al. (2004) and most recently by Assis et al. (2016) have helped clarify the relationships of Pecluma , which show it sister to Phlebodium and that combined clade sister to Pleopeltis .