Pleopeltis Humb. & Bonpl. ex Willd., Sp. Pl.

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

Pleopeltis Humb. & Bonpl. ex Willd., Sp. Pl. , ed. 4 [Willdenow], 5: 211. 1810.

= Marginaria Bory, Dict. Class d’Hist. Nat. 6: 587. 1824.

= Dicranoglossum J.Sm., Bot. Voy. Herald (Seemann) 232. 1854.

Pleopeltis is recognized by the simple or pinnatifid blades with sparse to dense peltate scales, and ovate to elongate sori with peltate, scalelike, often deciduous paraphyses. Most of the pinnate species placed here in Pleopeltis were until recently considered to belong to Polypodium , but have been transferred to Pleopeltis by Smith & Tejero (2014), as a result of molecular studies ( Schneider et al. 2004, Otto et al. 2009). The species with simple blades may be confused with Adetogramma chrysolepis , which has free veins, and species of Microgramma , which have round sori with filamentous, sometimes branched paraphyses. Pleopeltis is the largest genus of Polypodiaceae with about 90 species, mainly in the Neotropics, with a few species from Africa to India and Sri Lanka (Smith & Tejero 2014); 21 species are recorded for Bolivia, and the Andes are a major center of diversification for the genus. Three new species were recently described from Bolivia ( Kessler & Smith 2005), and, in the same paper, 12 species of Polypodium were transferred to Pleopeltis .

Several presumably natural groups of species occur with Pleopeltis , namely the P. furfuraceum and P. squamatum groups ( Maxon 1916a, 1916b; de la Sota 1966); the P. macrocarpa group ( Weatherby 1922, Hooper 1995), all simple-bladed species; the P. plebeia group ( Maxon 1916a); and P. polypodioides and allies ( Sprunt et al. 2011). Some of these groups possess nectaries ( Koptur et al. 1982). Characters distinguishing the species in Bolivia include: rhizome scale color (concolorous vs. weakly or sharply bicolorous with a median black stripe); rhizome scale aspect (adpressed vs. spreading); scale size, on rhizomes and lamina; scale margins (subentire to fimbriate or crispate); blade dissection (simple vs. pinnatifid or pinnatisect); blade base (truncate vs. with numerous gradually reduced proximal pinnae); blade size and shape; pinna aspect (spreading vs. slightly ascending vs. strongly ascending); blade scaliness (slight, moderate, or completely covering the abaxial lamina). Chromosome base number varies in the genus, with x = 34, 35, or 37 (mostly); more data are needed to judge the importance of this character, as related to affinities and evolution in the genus. Twenty-eight species of Pleopeltis were examined by Sundue et al. (2011) under epifluoresence microscopy and found to have chlorophyllous spores; previously, Smith (1981) had observed “green spores” in P. remota , with spores appearing to germinate inside ± intact sporangia.

Hybrids appear to be relatively common in Pleopeltis , sometimes between seemingly rather disparate species, as judged by morphology. Pleopeltis × leucospora (Klotzsch) T.Moore is widespread in the Neotropics (Hispaniola; Costa Rica; Colombia to Peru, southern Brazil), and Wagner & Wagner (1975) presented evidence that this is a hybrid between Pleopeltis macrocarpa , a simple-bladed species, and Pleopeltis thyssanolepis , a pinnatifid species; both of these putative parents occur in Bolivia, and so hybridization is possible. Often, hybrids in this genus (and others) can be detected by major irregularities in blade lobing; this is particularly true if the putative hybrids are between species having different blade dissection types. The occurrence of such hybrids is one of the pieces of evidence suggesting the generic merger of simple-bladed Pleopeltis with scaly, pinnatifid species of Polypodium . Mickel & Smith (2004) discussed several other Pleopeltis hybrids in Mexico, and Cerón-Carpio et al. (2017) added to this list, documenting three additional hybrid taxa in Mexico.

Dicranoglossum has historically been separated from Pleopeltis by having blades with very few pinna pairs and very small, blackish, round scales scales on the lamina abaxially. Molecular data suggest its inclusion in Pleopeltis ( Schneider et al. 2004) . Affinities of Pleopeltis appear to be with Pecluma s.l. and with Phlebodium ( Pecluma clade of Otto et al. 2009; Schneider et al. 2004).