Taxonomía y florística

 

Pleopeltis (Polypodiaceae), a redifinition of the genus and nomenclatural novelties

 

Pleopeltis (Polypodiaceae), una redefinición genérica y novedades nomenclaturales

 

Alan R. Smith¹ and J. Daniel Tejero-Díez^2,3

 

¹ University of California, University Herbarium, Berkeley, USA

² Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Iztacala, Carrera de Biología, Tlalnepantla, Estado de México, Mexico

³ Correspondence author: tejero@unam.mx

 

Received: January 18th, 2013
Accepted: May 2nd, 2013

 

Abstract

Recent evidence from morphological, cytological, and gene sequencing studies has provided several additional evidence that the genus Pleopeltis (Polypodiaceae) requires redefinition to include other polypod genera and species with peltate scales on the leaf blades. Groups to be included are Polypodium subg. Marginaria (species treated in the group of P. polypodioides (L.) Watt by Moran), and also including the P. squamatum and P. plebeium groups, Dicranoglossum, Microphlebodium, Neurodium, and Pseudocolysis. In this paper, we review all species of Polypodiaceae that we believe belong to Pleopeltis and make 35 species combinations, one varietal combination, one new status, and five hybrid combinations. In addition, three new names are necessary for species prevented from transfer because to do so results in homonymy. As redefined, Pleopeltis comprises ca. 90 species, mainly in the New World, but with two species and one hybrid in Africa, India, and Sri Lanka; it excludes Lepisorus in Asia and Africa, as well as many other especially simple-bladed Old World species once placed in Pleopeltis but now included in other Paleotropical genera, e.g., Lemmaphyllum, Leptochilus, and Selliguea. We provide a key to separate the American polypod genera, and address biogeographical data that derive from this new circumscription. In two appendices, we list previously accepted taxa of Pleopeltis for which combinations are already available, as well as salient synonymy.

Key words: fern classification, Neotropics, new combinations, Polypodium, synonymy.

 

Resumen

La evidencia reciente proveniente de estudios morfológicos, citológicos y de la secuenciación de genes en Polypodiaceae, ha proporcionado información suficiente para considerar que el género Pleopeltis requiere una redefinición, con el fin de incluir otros géneros y especies de la familia que presentan escamas peltadas en las hojas; aquellas consideradas hasta el momento como Polypodium subg. Marginaria (especies tratadas en el grupo de Polypodium polypodioides (L.) Watt por Moran), también de los grupos de P. squamatum y P. plebeium, y de Dicranoglossum, Microphlebodium, Neurodium y Pseudocolysis. En este trabajo se revisaron todas las especies de Polypodiaceae que, de acuerdo a las evidencias morfológicas, al parecer pertenecen a Pleopeltis. En total se realizaron 35 combinaciones nuevas a nivel de especie, una en el nivel de variedad, un nombre con rango nuevo y cinco en los híbridos. Adicionalmente, fue necesario establecer tres nuevos nombres, dado que la transferencia a Pleopeltis dio lugar a homonimias. La nueva redefinición de Pleopeltis comprende ca. 90 especies, sobre todo en el Nuevo Mundo, dos especies y un híbrido en África, India y Sri Lanka; se excluye a Lepisorus en Asia y África. Se proporciona una clave para separar los géneros de Polypodiaceae americanos y la distribución geográfica que se deriva de esta nueva circunscripción. En dos apéndices se enumera los nombres para las combinaciones de Pleopeltis que ya estaban disponibles, así como la sinonimia resultante de los cambios nomenclaturales.

Palabras clave: clasificación de helechos, Neotropical, nuevas combinaciones, Polypodium, sinonimia.

 

The classical fern genus Polypodium, described by Linnaeus (1753), has been the home at one time of a huge number of distantly related species. Historically, characters common to most species assigned to Polypodium s.l. include a generally long- to short-creeping rhizome with two rows of alternating dorsal leaves, and usually round to oblong (rarely linear), exindusiate sori. In the last two hundred years, many genera have been segregated from classical Polypodium s.l., in both the New World and Old World. Those segregates most often recognized in the Neotropics include Campyloneurum, Dicranoglossum, Microgramma, Microphlebodium, Neurodium, Niphidium, Pecluma, Phlebodium, Pleopeltis, Serpocaulon, and Synammia. With existing evidence from both morphology and molecular data, some of these genera can be maintained in their approximate original circumscription, e.g., Synammia (Schneider et al., 2006) and Serpocaulon (Smith et al., 2006); while others contain heterogeneous elements, e.g., Polypodium (Hennipman et al., 1990), or are not monophyletic. Sometimes, the evidence for polyphyly has come through examination of morphological characters (Tejero-Díez, 2005; Tejero-Díez et al., 2010); other evidence has accumulated as a result of cytological studies, especially the discovery of intergeneric hybrids (Gómez-Pignataro, 1975; Wagner and Wagner, 1975; Anthony and Schelpe, 1985; Mickel and Beitel, 1987) that contraindicate current taxonomic circumscriptions. Additional evidence derives from recent molecular studies (e.g., Schneider et al., 2004; Otto et al., 2009; Sprunt et al., 2011). One of the most problematic genera is Pleopeltis, whose circumscription is the subject of this paper.

Pleopeltis was segregated from Polypodium by Willdenow 200 years ago. Initially, it contained only a single species, the type (Pleopeltis angusta Humb. & Bonpl. ex Willd.), but many authors have expanded its limits to include over 200 species, both in the Old and New Worlds. Nearly all of those species placed in Pleopeltis from the Paleotropics are now included in other genera, particularly Lepisorus and Selliguea, but other genera as well. The former genus, also with simple, often scaly blades, has been partly monographed by Zink (1993), and has been shown to be allied to the microsoroid ferns (Schneider et al., 2004) in an exclusively paleotropical tribe Lepisoreae (Wang et al., 2010a, b), and not to Pleopeltis. Also, the Malesian species of Lepisorus were treated by Hovenkamp (1998a, b) and the Chinese ones by Qi and Zhang (2009). Some other Old World species, especially simple-bladed ones, were also earlier combined in Pleopeltis, but are now placed in Selliguea and Microsorum.

As defined more recently (e.g., by Smith, 1981; Tryon and Tryon, 1982; Mickel and Beitel, 1988, Lellinger, 1989, Tryon and Stolze, 1993; Hooper, 1994, 1995; Lorea-Hernández, 1995; Mickel and Smith, 2004), Pleopeltis was believed to comprise a predominantly New World group of about ten species, the genus characterized by generally simple blades (except the type, P. angusta, which has pinnatifid blades with only a few pinna-pairs), a complex netted venation consisting of areoles of two or three orders, with 1-3 free included veins, sori borne at junction of these ultimate veins (compital sori), and peltate scales, at least in immature sori and often on laminar tissue too.

In addition, hybrids have been found between Pleopeltis and Polypodium (×Pleopodium) in Africa (Anthony and Schelpe, 1985) and America (Wagner and Wagner, 1975; Mickel and Beitel, 1987). These "intergeneric" hybrids have called into question the circumscription of both Pleopeltis and Polypodium. Also, some of the species now usually regarded as belonging to Polypodium were, in fact, originally described in Pleopeltis, e.g., P. pinnatifida Hook. & Grev. Even with the cytological evidence, many scaly-bladed species are still almost unanimously considered as belonging to Polypodium in various taxonomic revisions (Maxon, 1916; Weatherby, 1922; 1947; de la Sota, 1960, 1966; Tryon and Tryon, 1982), as well as in many recent floras, e.g., for Mexico (Mickel and Smith, 2004), Mesoamerica (Moran, 1995), the Venezuelan Guayana (Smith et al., 1995), and Peru (Tryon and Stolze, 1993).

In the early 1990s, the Flora of North America North of Mexico (FNANM) project became the impetus for renewed investigation of the affinities of certain scaly polypods from the southern United States. Provided with preliminary molecular and isozyme data, Windham (1993) became convinced of the unnaturalness of Polypodium and the affinities of certain Polypodium species to Pleopeltis. in a prelude to their account of Polypodium and Pleopeltis in FNANM (FNAEC, 1993), Windham (1993) transferred several species from Polypodium to Pleopeltis: P. guttatum, P. polypodioides, P. riograndensis, and P. thyssanolepis.

In the last decade, the advent of cladistic analysis using both morphological and gene sequence data has provided additional strong evidence that Polypodium s.l. is clearly polyphyletic, and that many species of Polypodium with peltate and persistent laminar scales heretofore treated in Polypodium subg. Marginaria, as well as species in the Polypodium polypodioides group (Moran, 1995), Dicranoglossum, Microphlebodium, Neurodium, and Pseudocolysis, are much more closely allied to species of Pleopeltis (Schneider et al., 2004; Tejero-Díez, 2005; Otto et al., 2009) than they are to Polypodium s.str. The scale character, especially, helps to redefine the circumscription of Pleopeltis (Tejero-Díez, 2005; Otto et al., 2009). Using this character and others, species of Polypodium from North America north of Mexico (Windham, 1993; Hooper, 1995) and some Polypodium spp. in South America (de la Sota, 2003; Kessler and Smith, 2005; de la Sota et al., 2007; Salino, 2009; Prado and Hirai, 2010) have already been given new combinations in Pleopeltis. in this paper we review all polypod species that we believe belong to a redefined Pleopeltis and make the necessary new combinations for taxa that lack a name in Pleopeltis. These taxonomic judgments reflect the totality of data available on the group, both monographic information (with morphology as the prime source of characters) and recent molecular data (especially Otto et al., 2009). In addition, we address biogeographical data that derive from the review of the literature.

From discussion presented above, we believe that there is no real or practical alternative to the redefinition of Pleopeltis (and thus also of Polypodium). We therefore emend the circumscription of Pleopeltis as indicated below, and transfer to it 38 species heretofore usually placed in Polypodium. Three new names (nom. nov.) are coined in Pleopeltis for species where the available name is pre-empted, and one varietal epithet is recombined; five hybrid combinations are also made. With additional data, it may become feasible, even desirable, to provide an infrageneric classification of the species within Pleopeltis, but at this point the data are inconclusive and inadequate, and in fact can be interpreted to indicate that no such subdivision may be possible. Clearly, there are groups of closely allied species, as suggested by previous monographers (Maxon, 1916; Weatherby, 1922, 1939; de la Sota, 1966), but these groups may need additional redefinition to make them monophyletic. A preliminary attempt at placing known species into subgroups of related species is made in the summary. This assessment is based on both molecular results (largely, Otto et al., 2009; Sprunt et al., 2011) and previous monographs, cited above.

 

Methods

We base our taxonomic decisions -the new combinations given below- on a knowledge of the species in the field and herbarium, information available in regional floras from U.S.A. (FNAEC, 1993), Mexico (Smith, 1981; Mickel and Beitel, 1988; Mickel and Smith, 2004), Mesoamerica (Lellinger, 1989; Lorea-Hernández, 1995; Maxon in Yuncker, 1938; Moran, 1995; Stolze, 1981), the Antilles (Proctor, 1977, 1985, 1989), and South America (Smith, 1985; Tryon and Stolze, 1993; Smith et al., 1995; J0rgensen and León-Yánez, 1999), as well as unpublished work by Smith and Mostacero on Venezuelan ferns and by Kessler and Smith on Bolivian ferns. We have also consulted relevant monographs and revisions on Polypodium (Maxon, 1916; Weatherby, 1922; de la Sota, 1966) and Pleopeltis (Hooper, 1994). Additional databases that have proven helpful are IPNI (International Index to Plant Names: http://www.ipni.org:80/ipni/plantnamesearchpage.do) and Tropicos (http://www.tropicos.org/).

 

Results

Pleopeltis Humb. & Bonpl. ex Willd., Sp.pl., ed. 4 [Willdenow], 5:211. 1810. - Polypodium subg. Pleopeltis (Humb. & Bonpl. ex Willd.) C.Chr., Ind. Fil. L. 1906. - Type: Pleopeltis angusta Humb. & Bonpl. ex Willd. Marginaria Bory, Diet. Class. d'Hist. Nat. 6:587. 1824. -Polypodium L. subg. Marginaria (Bory) C.Chr., Ind. Fil. L. 1906. - Type: Marginaria polypodioides (L.) Tidestr. [= Acrostichum polypodioides L.] = Pleopeltis polypodioides (L.) E.G.Andrews & Windham.

Lepicystis (J. Sm.) J. Sm., London J. Bot. 1:195. 1842. - Goniophlebium sect. Lepicystis J.Sm., J. Bot. (Hook.) 4:56. 1841. - Type: Goniophlebium incanum J.Sm. = Pleopeltis polypodioides (L.) E.G. Andrews & Windham.

Neurodium Fée, Mém. Soc. Mus. Hist. Nat. Strasbourg 4:201. 1850. - Type: Neurodium lanceolatum (L.) Fée = Pleopeltis marginata A.R.Sm. & Tejero.

Paltonium C. Presl, Epim. Bot. 156. 1851. [Abh. Königl. Böhm. Ges. Wiss., ser. 5, 6:516. 1851]. Nom. superfl. for Neurodium Fée, and with the same type.

Eschatogramme Trevis., Atti Ist. Veneto, ser. 2, 2:168. 1851. Nom. nud.

Dicranoglossum J.Sm., Bot. Voy. Herald 232. 1854. - Lectotype (designated by J.Smith, Hist. Filicum 120. 1875): Dicranoglossum furcatum (L.) J.Sm. = Pleopeltis furcata (L.) A.R.Sm.

Cheilogramma Maxon, Proc. U. S. Natl. Mus. 23:630. 1901 (also Maxon in Underwood, Our native ferns, ed. 6. 1900). 1901. - Type: Cheilogramma lanceolata (L.) Maxon = Pleopeltis marginata A.R.Sm. & Tejero.

Marginariopsis C.Chr., Dansk. Bot. Ark. 6:42. 1929. - Type: Marginariopsis wiesbaurii (Sodiro) C.Chr. = Pleopeltis wiesbaurii (Sodiro) Lellinger.

Pseudocolysis L.D.Gómez, Brenesia 10-11:116. 1977. - Type: Pseudocolysis bradeorum (Rosenst.) L.D.Gómez = Pleopeltis bradeorum (Rosenst.) A.R.Sm. & Tejero.

×Pleopodium Schelpe & N.C.Anthony, Bothalia 15:557. 1985. - Type: ×Pleopodium simianum Schelpe & N.C.Anthony [= Pleopeltis macrocarpa (Bory ex Willd.) Kaulf. x Polypodium polypodioides (L.) Watt subsp. ecklonii (Kunze) Schelpe] = Pleopeltis ×simiana (Schelpe & N.C.Anthony) N.R.Crouch & Klopper.

Microphlebodium L.D.Gómez, Phytologia 59:58, text f. 1985. - Type: Microphlebodium muenchii (Christ) L.D.Gómez [= Polypodium muenchii Christ] = Pleopeltis muenchii (Christ) A.R.Sm. & Tejero.

Plants epiphytic, epipetric, or terrestrial; rhizomes long- to short-creeping, branched, leaves distant to clumped; rhizome scales concolorous to often bicolorous, non-clathrate to clathrate on the margins, cells of a central longitudinal band sometimes blackened and thickened, the transition to clathrate cells often abrupt, scales generally deltate, narrowly deltate, or lanceate, bases peltate, margins entire to denticulate, fimbriate, or erose, surfaces comose or glabrous; blades simple to pinnatifid, rarely pinnate-pinnatifid or more divided, monomorphic to subdimorphic or holodimorphic in a few species, stipitate, eventually (sometimes tardily) articulate; laminar tissue firm, generally subcoriaceous to coriaceous, sparsely to densely scaly with peltate, orbicular to ovate-lanceolate scales; veins free to netted, if netted, the main areoles in one row on each side of costa with 1-3 free or netted included veins; sori round to oblong, rarely marginal and coalescing or linear, in one row on each side of midrib (rachis or costae, depending on blade dissection), exindusiate, with round, peltate scales (at least in immature sori) or naked, each sorus arising at apex of a single fertile vein or at the junction of several included veins (sori compital); sporangia glabrous; spores bilateral, yellowish or sometimes greenish, shallowly to prominently verrucate; x = 34, 35, 37.

Other morphological characters that help to establish the limits of Pleopeltis, or apply to subgroups within Pleopeltis, are: (a) the presence of leaf nectaries at the acroscopic bases of pinnae; (b) vascular bundles in stipes that fuse in a V pattern (Tejero-Díez et al., 2010), where three small vascular bundles are fused in the proximal portion of the stipe and two large vascular bundles are fused in the distal portion; (c) blades with bifacial anatomy (Tejero-Díez et al., 2010); and (d) poikilohydrous character (sensu Kessler and Siorak, 2007). Thus far, at least 12 species here placed in Pleopeltis are known to produce either green spores or the spores autofluorescense, which is an indication of chlorophyll production. Not all species of Pleopeltis have shown this characteristic, and the feature may not be uniform within a species (Sundue et al., 2011). The occurrence of chlorophyllous spores in other polypod genera (grammitids always produce chlorophyllous spores) appears to be relatively rare, having been found in species of Loxogramme, Platycerium, and Christiopteris. Green spore production is uncommon in ferns, but is a synapomorphy of a few families (Equisetaceae, Hymenophyllaceae, onocleaceae, and osmundaceae) or other large clades (grammitids, in Polypodiaceae), and also appears also to be relatively common in a few other genera (e.g., Elaphoglossum, Lomariopsis).

According to Otto et al. (2009), Pleopeltis is a monophyletic group represented by three major subgroups. Pleopeltis bradeorum lies at the base of the Pleopeltis clade. Otto's study, coupled with that by Schneider et al. (2004), clearly call into question the historical definition of Pleopeltis.

The new combinations proposed here are relevant to ecological studies because species of Pleopeltis have special ecological preferences for life in the forest canopy in the temperate sub-humid and humid zones of the Neotropics (Wolf and Flamenco-S., 2006), where scaly blades, poikilohydrous character, and bifacial anatomy of blades in some species are obviously advantageous (Dubuisson et al., 2009; Tejero-Díez, 2009; Moran, 2004: 154). The new combinations are also necessary for forthcoming taxonomic treatments, regional floras, ecological interpretations, and ongoing phylogenetic studies.

 

New combinations proposed

Pleopeltis alan-smithii (R.C.Moran) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium alan-smithii R.C.Moran (1990: 845, f. 1) - SW Mexico, Guatemala, Honduras, Nicaragua, Salvador (Moran, 1995; Mickel and Smith, 2004).

Pleopeltis aturensis (Maury) A.R.Sm., comb. nov.

Basionym: Polypodium aturense Maury (1889: 134, f. 3)- S Venezuela (Smith et al., 1995).

Pleopeltis balaonensis (Hieron.) A.R.Sm., comb. nov.

Basionym: Polypodium balaonense Hieron. (1905: 529) -Colombia, Ecuador, Panama, Peru (de la Sota, 1966; Moran, 1995).

Pleopeltis bradeorum (Rosenst.) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium bradeorum Rosenst. (1912: 279) - S Belize, Costa Rica, Honduras, Mexico, Nicaragua, Panama (Moran, 1995).

Pleopeltis christensenii A.R.Sm., nom. nov.

Basionym: Eschatogramme panamensis C.Chr. (1929: 37) - Dicranoglossum panamense (C.Chr.) L.D.Gómez, Brenesia 16:46. 1976, not Pleopeltis panamensis (Weath.) Pic.Serm. (1968: 189) - W Colombia, Costa Rica, NW Ecuador, Honduras, Nicaragua, Panama (Moran, 1995).

Pleopeltis collinsii (Maxon) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium collinsii Maxon (1916: 583, t. 41) - S Mexico (de la Sota, 1966; Moran, 1995; Mickel and Smith, 2004).

Pleopeltis cryptocarpa (Fée) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium cryptocarpon Fée (1857: 88) - Guatemala, Honduras, S Mexico, Nicaragua (Maxon,1916; Moran, 1995; Mickel and Smith, 2004).

Pleopeltis ecklonii (Kunze) A.R.Sm., comb. nov.

Basionym: Polypodium ecklonii Kunze (1836: 498) -Malawi, Mozambique, South Africa, Tanzania, Zimbabwe.

Pleopeltis fallacissima (Maxon) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium fallacissimum Maxon (1916: 567) - NE Mexico (Maxon, 1916; Mickel and Smith, 2004).

Pleopeltis fayorum (R.C.Moran & B.0llg.) A.R.Sm., comb. nov.

Basionym: Polypodium fayorum R.C.Moran & B. 0llg. (1998: 437, f. 4) - Ecuador, Peru.

Pleopeltis fimbriata (Maxon) A.R.Sm., comb. nov.

Basionym: Polypodium fimbriatum Maxon (1916: 596) - Colombia, Ecuador (de la Sota, 1966).

Pleopeltis friedrichsthaliana (Kunze) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium friedrichsthalianum Kunze (1850(2): 55, t. 123) - Costa Rica (Maxon, 1916; Moran, 1995).

Pleopeltis furcata (L.) A.R.Sm., comb. nov.

Basionym: Pteris furcata L. (1753: 1073) -Brazil, Cuba, Colombia, Ecuador, Hispaniola, Suriname, Trinidad, Venezuela.

Pleopeltis furfuracea (Schltdl. & Cham.) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium furfuraceum Schltdl. & Cham. Pleopeltis (POLYPODIACEAE), A REDIFINITION OF THE GENUS AND NOMENCLATURAL NOVELTIES (1830: 607) - Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama (Maxon, 1916; Moran, 1995; Mickel and Smith, 2004). Attribution of this species to Bolivia and Peru (Moran, 1995; Mickel and Smith, 2004) pertains to Pleopeltis disjuncta M.Kessler & A.R.Sm. (Kessler and Smith, 2005).

Pleopeltis hookeri A.R.Sm., nom. nov.

Basionym: Taenitis furcata Willd. var. polypodioides Hook. (1864: 188) - Dicranoglossum polypodioides (Hook.) Lellinger, Selbyana 2:283. 1978, not Pleopeltis polypodioides (L.) E.G.Andrews & Windham (1993) - Ecuador, Peru.

Pleopeltis insularum (C.V.Morton) A.R.Sm., comb. nov.

Basionym: Polypodium bombycinum Maxon var. insularum C.V.Morton (1957: 193) - Polypodium insularum (C.V.Morton) de la Sota, Revista Mus. La Plata, Secc. Bot. 10:152, f. 1, 4, 12, 15, 16. 1967. - Ecuador (Galápagos Isl.) (de la Sota, 1966).

Pleopeltis lepidotricha (Fée) A.R.Sm. & Tejero, comb. nov.

Basionym: Goniophlebium lepidotrichum Fée (1857: 93) - Polypodium lepidotrichum (Fée) Maxon - SE Mexico (de la Sota, 1966; Mickel and Smith, 2004).

Pleopeltis lindeniana (Kunze) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium lindenianum Kunze (1851: 83, t. 134) - Belize, S Costa Rica, El Salvador, Guatemala, Honduras, S Mexico, Nicaragua, (Maxon, 1916; Smith, 1981; Moran, 1995).

Pleopeltis macrolepis (Maxon) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium macrolepis Maxon (1916: 584) - Costa Rica, Panama (de la Sota, 1966).

Pleopeltis madrensis (J.Sm.) A.R. Sm. & Tejero, comb. nov.

Basionym: Polypodium madrense J.Sm., in Seemann (1856: 338, t. 73) - Mexico (Moran, 1995; Mickel and Smith, 2004).

Pleopeltis marginata A.R.Sm. & Tejero, nom. nov.

Basionym: Pteris lanceolata L. (1753: 1073) (not Pleopeltis lanceolata (L.) Kaulf. (1824: 245) -Antilles, Bahamas, Belize, Costa Rica, French Guiana, Guatemala, Honduras, 5 Mexico, Nicaragua, SE USA,. This species has generally been treated in Neurodium (Pacheco, 1995).

Pleopeltis microgrammoides (Mickel & A.R.Sm.) A.R.Sm. 6 Tejero, comb. nov.

Basionym: Polypodium microgrammoides Mickel & A.R.Sm. (2000: 236, f. 1D-G) - C Mexico (Mickel and Smith, 2004).

Pleopeltis monosora (Desv.) A.R.Sm., comb. nov.

Basionym: Polypodium monosorum Desv. (1811: 319) - Colombia, Ecuador, Peru (Maxon, 1916; Tryon and Stolze, 1993).

Pleopeltis montigena (Maxon) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium montigenum Maxon in Yuncker Botanical Sciences 92 (1): 43-58, 2014 (1938: 17: 306) - Costa Rica, Panama (Moran, 1995; Mickel and Smith, 2004).

Pleopeltis murora (Hook.) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium murorum Hook. (1837: t. 70) - Costa Rica, Colombia, Ecuador, Hispaniola, Venezuela (Maxon, 1916; Moran, 1995).

Pleopeltis myriolepis (Christ) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium myriolepis Christ in Bommer & Christ (1896: 661) - Costa Rica, Panama (de la Sota, 1966; Moran, 1995).

Pleopeltis platylepis (Mett. ex Kuhn) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium platylepis Mett. ex Kuhn (1869: 137) - Guatemala, Mexico, Venezuela (Maxon, 1916; Moran, 1995; Mickel and Smith, 2004).

Pleopeltis plebeia (Schltdl. & Cham.) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium plebeium Schltdl. & Cham. (1830: 607) - Costa Rica, Guatemala, El Salvador, Honduras, Mexico, Nicaragua, Panama (Maxon, 1916; Moran, 1995; Mickel and Smith, 2004).

Pleopeltis polypodioides (L.) E.G.Andrews & Windham var. knoblochiana (Mickel) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium polypodioides (L.) Watt var. knoblochianum Mickel in Mickel and Smith (2004: 502, f. 231M-R) - NW Mexico (Chihuahua, Sinaloa, Sonora) (Mickel and Smith, 2004).

Pleopeltis pyrrholepis (Fée) A.R.Sm. & Tejero, comb. nov.

Basionym: Goniophlebium pyrrholepis Fée (1857: 94) - S Mexico (de la Sota, 1966; Moran, 1995; Mickel and Smith, 2004).

Pleopeltis rosei (Maxon) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium rosei Maxon (1916: 594) - Mexico (de la Sota, 1966; Moran, 1995; Mickel and Smith, 2004). The occurrence of this species in Honduras cited by Moran (1995) and Nelson et al. (1996) is suspect, and the record for Costa Rica, as reported by Moran (1995), is a misidentified specimen, and is instead Pleopeltis tico. We consider Pleopeltis rosei a Mexican endemic.

Pleopeltis rzedowskiana (Mickel) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium rzedowskianum Mickel in Mickel and Smith (2004: 507-508, f. 236 O-S) - W Mexico (Mickel and Smith, 2004).

Pleopeltis sanctae-rosae (Maxon) A.R.Sm. & Tejero, comb. nov.

Basionym: Goniophlebium sanctae-rosae Maxon (1909: 8) - Guatemala, El Salvador, Honduras, S Mexico, Nicaragua (de la Sota, 1966; Moran, 1995; Mickel and Smith, 2004).

Pleopeltis segregata (Baker) A.R.Sm., comb. nov.

Basionym: Polypodium segregatum Baker in Hooker and Baker (1874: 510) - Ecuador.

Pleopeltis steirolepis (C.Chr.) A.R.Sm., comb. nov.

Basionym: Polypodium steirolepis C.Chr. (1917: 33) - Colombia, Ecuador, Venezuela.

Pleopeltis subnuda (C.Chr.) A.R.Sm., comb. nov.

Basionym: Eschatogramme furcata (L.) C.Chr. var. subnuda C.Chr. (1929: 36) - Bolivia, Peru (Tryon and Stolze, 1993).

Pleopeltis tico (A.Rojas) A.R.Sm., comb. nov.

Basionym: Polypodium tico A.Rojas (1996: 42-46) - Costa Rica.

Pleopeltis villagranii (Copel.) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium villagranii Copel. (1941: 292, t. 44) - E Mexico (Mickel and Smith, 2004).

Pleopeltis xantholepis (Harr.) A.R.Sm., comb. nov.

Basionym: Polypodium xantholepis Harr. (1877: 36) - Peru (Maxon, 1916); closely related to Pleopeltis pycnocarpa (Tryon and Stolze, 1993) and possibly Pleopeltis oreophila (Sundue, pers. comm.).

 

Hybrids

Pleopeltis xaspidiolepis (Baker) A.R.Sm., comb. nov.

Basionym: Polypodium aspidiolepis Baker (1887: 26) - Costa Rica = Pleopeltis friedrichsthaliana x thyssanolepis - Costa Rica (Gómez-Pignataro, 1975; Wagner et al., 1977).

Pleopeltis xbartlettii (Weath.) A.R.Sm. & Tejero, comb. nov.

Basionym: Polypodium bartlettii Weath. (1935: 56) -×Pleopodium bartlettii (Weath.) Mickel & Beitel (1987: 20, t. 1K-L) = putative hybrid between Pleopeltis polylepis and perhaps P. polypodioides - Mexico (Mickel and Smith, 2004).

Pleopeltis xleucospora (Klotzsch) T.Moore, Ind. fil. lxxvii. 1857, pro sp.

Basionym: Polypodium leucosporum Klotzsch (1847: 404) = Pleopeltis macrocarpa x thyssanolepis (see Tryon and Stolze, 1993) - Bolivia, S Brazil, Colombia, Costa Rica, Jamaica, Peru, Venezuela.

Pleopeltis xpinnatisecta (Brade) A.R.Sm., comb. nov.

Basionym: Polypodium furfuraceum Schltdl. & Cham. f. pinnatisectum Brade 1969: 16, t. 5), as "pinnatisecta" = Pleopeltis friedrichsthaliana x P. furfuracea - Costa Rica (Lellinger, 1989).

Pleopeltis xtricholepis (Mickel & Beitel) A.R.Sm. & Tejero, comb. nov.

Basionym: ×Pleopodium tricholepis Mickel and Beitel (1987: 17) - Mexico (Mickel and Smith, 2004).

 

Discussion

In this paper, we expand the circumscription of Pleopeltis. Using morpho-anatomical and molecular evidence (Tejero-Díez, 2005; Otto et al., 2009; Sprunt et al., 2011), the genus now comprises primarily New World polypods with peltate or rarely basifixed, persistent laminar scales. We make 35 new combinations, one varietal combination, one new status, and coin three new names, which add to the list of species belonging to Pleopeltis, giving a total of ca. 90 Pleopeltis species (with seven varieties and eight named hybrids). As emended, Pleopeltis now has the largest number of species of any genus of Neotropical Polypodiaceae, and is one of the largest genera of Polypodiaceae in the World, approaching the Old World polypod genus Microsorum, which is, of now, still ill-defined.

Tejero-Díez (2005) and Otto et al. (2009) indicated that peltate and persistent laminar scales, which are lacking in the related genera Pecluma (Evans, 1969) and Polypodium, are the principal characters that redefine Pleopeltis. Basifixed blade scales may occur in some specimens of Phlebodium pseudoaureum (Cav.) Lellinger or on costae and veins in Microgramma, Pecluma, Polypodium hartwegianum, and Serpocaulon. Not all species of a redefined Pleopeltis have peltate scales; an exceptional species is P. muenchii, having subpeltate scales, and scales appear to be completely absent on the blades of P. marginata.

The following key, excluding grammitid genera and Phymatosorus, a sparingly naturalized genus (Tejero-Díez and Torres-Díaz, 2012), will assist in determining the American polypod genera (Polypodiaceae):

1.	Spores tetrahedral, green; blades always lacking scales; petiole bases nearly always with a singular vascular bundle; veins usually free (with rare exceptions, e.g., Enterosora), if areolate, as in Loxogramme, then areoles without included veinlets.

	2.	Sori generally round; blades generally pinnatifid or pinnatisect, a few spp. simple...................................................Polypodiaceae, Grammitidoideae
	2.	Sori linear, oblique between the midrib and blade margins; blades always simple..........................Loxogramme

1.

Spores bilateral, whitish to amber-yellow (rarely greenish, e.g., some species of Pleopeltis); blades often with some scales; petioles bases usually with more than a single vascular bundle (except Pleopeltis fallax; some species of the Polypodium vulgare group have one vascular bundle at the distal end of petioles); veins free or often variously anastomosing and the areoles with included veinlets.

		3.	Leaves strongly dimorphic, the sterile forming a "nest" or basket; laminar hairs stellate; sporangia acros tichoid, in large patches at tips of fertile leaves or in sinuses of forking blades; only Peru and Bolivia............................Platycerium
		3.	Leaves monomorphic, if dimorphic then sterile not nest- or basket-forming; laminar hairs, if any, not stellate, simple; sporangia in discrete sori, not usually localized at tips of fertile leaves or in sinuses; widespread in the Neotropics.

4.

Blades scaly, at least on the abaxial surfaces, sometimes the scales very small.

				5.	Blade scales basifixed, linear ............Phlebodium
				5.	Blade scales peltate or with peltate bases, round to ovate-cuspidate.

																6.	Sori with persistent filiform paraphyses..........................Microgramma
																6.	Sori without paraphyses, or paraphyses peltate (often caducous)........................................Pleopeltis

4.

Blades without scales or these confined to the costae and primary veins, usually basifixed.

7.

Blades simple.

8.

Sori elongate, marginal, with blade margins reflexed over the sori............Pleopeltis marginata

8.

Sori round or nearly so, usually nearer the midribs than the blade margins.

9.

Sori in one row on each side of the midribs, except Microgramma microsoroides with several rows (SE Brazil) and then with blades elliptic ..........................................................Microgramma

9.

Sori in 2 or more (up to ca. 20) ± regular rows on each side of midribs, except some specimens of Campyloneurum angustifolium and related spp., and then with blades linear-lanceolate.

10.

Sori usually in 2 or more rows between main lateral (secondary) veins; sporangia glabrous .............................. Campyloneurum

10.

Sori in 1 row between main lateral (secondary) veins; sporangia bearing minute multicellular hairs on capsules............. Niphidium

7.

Blades pinnatifi d to 1-pinnate, rarely more divided.

11.

Stipes without grooves adaxially, black to reddish brown; rhizome scales basifi xed (not auriculate); blades pectinate to 1-pinnate at bases; veins generally free or casually anastomosing, pinnae usually comb-like, usually > 20 lateral pairs per frond .................................. Pecluma

11.

Stipes grooved adaxially, at least distally, stramineous to brown; rhizome scales subpeltate (with two overlapping auricles); blades pinnatifi d, pectinate, or pinnate; veins often anastomosing, if free (Polypodium), then pinnae not comb-like, generally < 20 pairs per frond.

12.

Veins free, sometimes irregularly netted .................................................... Polypodium

12.

Veins regularly netted, at least in the basal part of the segments (pinnae).

13.

Marginal areoles present and steril(without included veins), in (1 complete) 2 or more alternating rows; spores tuberculate .................................................. Phlebodium

13.

Marginal sterile areoles absent, if present then irregular, not forming a regular row; spores rugulate, verrucate, papillate, low-tuberculate (Polypodium vulgare group), or with raised folds forming prominent wings (Serpocaulon).

14.

Sori in 2-4 rows between strongly delineated main lateral veins .............................Campyloneurum decurrens, C. magnificum

14.

Sori in a single row between the main lateral veins, which are apparent or not.

15.

Rhizome scales clathrate, at least in lateral or peripheral portions if not over their entire surface, or with the center blackened and sclerotic .......................... Serpocaulon

15.

Rhizome scales not clathrate, uniformly colored (concolorous) or occasionally bicolorous (darkened central portion, clathrate margins).

16.

Rhizome scales light brown (tan) to dark brown or bicolorous with dark brown or reddish central portion; areoles of blades elongate; spp. nearly all from north of the equator ............................. Polypodium

16.

Rhizome scales amber or orangish; vein areoles as long as wide; spp. from southern South America (Argentina, Chile, and Juan Fernández Islands) .................... ................................................ Synammia

 

Summary of geographical distribution of Pleopeltis. Species and infraspecific taxa of Pleopeltis are almost evenly divided between Mexico/Mesoamerica and South America. Seventy-six taxa are found in one or the other area, but not both, and several others barely extend their distributions into both parts of the Americas (e.g., P. christensenii into W Colombia, P. platylepis disjunct in W Venezuela, P. marginata into French Guiana; P. balaoensis and P. bombycina into Panama). Most species of Pleopeltis in the newly expanded sense are continental, but a few are endemic on Pacific (P. insularum, P. masafuerae, P. tridens) or Atlantic (P. trindadensis) islands. The Antilles have only a single endemic species (P. squamata) and only 11 species total, with most of these widespread on both continents. According to Otto et al. (2009), southern Mexico to Panama is the putative area of origin for Pleopeltis but it is likely that areas within both tropical South America (Andes, southern Brazil) and North America (Mexico, Costa Rica/Panama) have been important secondary centers of radiation, because relatively few species between the two areas are shared, and because morphological similarities among species endemic to both areas are evident. Only seven species can be considered wide-ranging in the Neotropics, and two of these have also colonized regions in southern Africa and adjacent areas.

In Mexico/Mesoamerica, at least four separate radiations are evident: (1) the simple-bladed group of Pleopeltis macrocarpa (including also P. complanata, P. conzattii, P. crassi-nervata, P. fructuosa, P. intermedia, P. mexicana, P. polylepis, P. stolzei, and the strongly dimorphic P. wiesbaurii) in the mountains of Mexico, extending into Mesoamerica and South America. The only simple-bladed species of Pleopeltis that are apparently not clearly a part of this clade are P. (Neurodium) marginata, P. (Microphlebodium) microgrammoides, and perhaps P. repanda; (2) a radiation of pinnati-fid species in the Pleopeltis plebeia group (including also P. alan-smithii, P. guttata, P. madrensis, P. montigena, and P. rzedowskiana); (3) a radiation of more heavily scaly-bladed, pinnatisect species related to P. lepidotricha (including also P. collinsii, P. macrolepis, P. myriolepis, P. pyrrholepis, P. rosei, P. sanctae-rosae, and P. tico, as well as P. squamata in the Greater Antilles); P. tridens, endemic to the Galápagos Islands, may be the sole representative of this clade south of the equator; and (4) the P. furfuracea group (including also P. cryptocarpa, P. friedrichsthaliana, P. lindeniana, P. platylepis, and P. villagranii), more poorly circumscribed (judging from the analyses by Otto et al., 2009), a largely Mexican and Central American, with blades pinnatisect to more divided and rather densely scaly abaxially, also with concolorous, tan to light brown rhizomes scales; Pleopeltis disjuncta, from Peru and Bolivia, is a strongly disjunct member of this clade, and P. platylepis, largely confined to Mexico and Guatemala, has an outlying population in Venezuela.

In South America, there are at least three main clades: (1) Pleopeltis remota and allies (including also P. appressa, P aturensis, P. bryopoda, P. buchtienii, P. coenosora, P. fayorum, P. fraseri, P. masafuerae, P. oreophila, P. orientalis, P. pinnatifida, P. pleopeltifolia, P. pycnocarpa, P. segregata, P. steirolepis, P. tweediana, and P. xantholepis), mostly confined to Andean regions, the species with sparingly to moderately scaly, pinnatifid or pinnatisect blades (more divided in P. monosora and P. murora), and rhizome scales with sharply to weakly bicolored scales, the mid-stripe sometimes black and sclerotic P. megalolepis, with nearly concolorous scales, may also belong to this clade; (2) the P. hirsutissima group (also P. bombycina, P. fimbriata, P. insularum, P. lepidopteris, P. minarum), these species with greatly reduced, densely scaly blades proximally species are largely confined to southeastern Brazil, Amazon regions, and lower elevations of the Andes, bordering the Amazon Basin; and (3) those species formerly treated in Dicranoglossum, related to Pleopeltis furcata (also P. christensenii, P. desvauxii, P. hookeri, and P. subnuda) they occur mostly at relatively low elevations around the edge of the Amazon Basin and in the Guianas, but some species extend also into Central America and the Antilles.

Using both morphological and molecular data, a few remaining species in Pleopeltis cannot clearly be placed in any of the above clades. These include the related pair P. microgrammoides and P. muenchii in Mexico and Central America; P. bradeorum in Central America (basal in Pleopeltis in the analysis by Otto et al., 2009); the complex of P. fallacissima, P. riograndensis, and P. thyssanolepis, in both Mexico, Central America, and South America, and the widespread P. polypodioides group, containing also P. ecklonii in South Africa and P. minima in S Brazil and adjacent countries. The relationships of P. angusta, the type of Pleopeltis, is not altogether clear either, but molecular data indicate an affinity to P. polypodioides, and beyond that to elements in the P. furfuracea group (Otto et al., 2009).

In the compilation below, the number of species in each country has been checked in floristic and monographic literature: Tryon and Conant, 1975; Proctor, 1977; Smith 1993; Tryon and Stolze, 1993; Rodríguez, 1995; Nelson et al., 1996; Boggan et al., 1997; J0rgensen and León-Yánez, 1999 Mickel and Smith, 2004; Monterrosa and Monro, 2008; Gómez and Arbeláez, 2009.

(1) North America (Mexico, from the Isthmus of Tehuantepec to U.S.A., excl. Florida) - 28 species, five vars., four hybrids; 14 endemic spp. and vars., the first extending into Chiapas (Pleopeltis collinsii, P. conzattii, P. fallacissima, P. guttata, P. lepidotricha, P. madrensis, P. microgrammoides, P. polylepis var. erythrolepis, P. polylepis var. polylepis, P. polypodioides var. knoblochiana, P. riograndensis, P. rosei, P. rzedowskiana, and P. villagranii), four endemic hybrids. Pleopeltis platylepis is also largely confined to this area, but its distribution extends to Guatemala, with a disjunct population in Venezuela.

(2) Central America (southern Mexico, Isthmus of Tehuantepec south to Panama) - 36 species, three vars., three hybrids; eight endemic spp. (Pleopeltis complanata, P. friedrichsthaliana, P. lindeniana, P. macrolepis, P. montigena, P. myriolepis, P. panamensis, and P. tico), two endemic hybrids.

(3) Caribbean Islands (Bahamas and Antilles) + SE U.S.A. - Seven species, two varieties, one hybrid; one endemic (Pleopeltis squamata).

(4) South America (excl. islands) - 50 species, two varieties, one hybrid; 36 endemics (Pleopeltis alborufula, P. appressa, P. aturensis, P. ballivianii, P. bradei, P. bryopoda, P. buchtienii, P. coenosora, P. disjuncta, P. fayorum, P. fimbriata, P. fraseri, P. hirsutissima, P. intermedia, P. lepidopteris, P. megalolepis, P. minarum, P. minima, P. monoides, P. monosora, P. oreophila, P. orientalis, P. pinnatifida, P. pleopeltidis, P. pleopeltifolia, P. polypodioides var. burchellii, P. pycnocarpa, P. repanda, P. segregata, P. steirolepis, P. stolzei, P. subnuda, P. subvestita, P. trindadensis, P. tweediana, and P. xantholepis).

(4a) South Pacific islands (Galápagos and Juan Fernández) - Four species; three endemics (Pleopeltis insularum, P. masafuerae, and P. tridens).

(4b) Andean region (39 spp., one hybrid; 25 endemic taxa, including 24 species + one variety (Pleopeltis appressa, P. ballivianii, P. bryopoda, P. buchtienii, P. coenosora, P. disjuncta, P. fayorum, P. fimbriata, P. fraseri, P. intermedia, P. megalolepis, P. minima, P. monosora, P. oreophila, P. orientalis, P. pinnatifida, P. polypodioides var. burchellii, P. pycnocarpa, P. segregata, P. steirolepis, P. stolzei, P. subnuda, P. subvestita, P. tweediana, and P. xantholepis). (4c) Amazonian region - Seven species; three endemics (Pleopeltis aturensis, P. desvauxii, and P. repanda). (4d) Southeastern Brazil and adjacent areas (Paraguay, Uruguay, NE Argentina) - Ten species; nine endemics (Pleopeltis alborufula, P. bradei, P. hirsutissima, P. lepidopteris, P. minarum, P. monoides, P. pleopeltidis, P. pleopeltifolia, and P. trindadensis).

(5) More widespread species, often throughout Neotropics, in two instances extending to, or with an outlier in, southern Africa and adjacent areas - Eight species (Pleopeltis astrolepis, P. desvauxii, P. furcata, P. macrocarpa, P. marginata, P. polypodioides, P. remota, and P. thyssanolepis).

 

Acknowledgments

We thank Michael Sundue, New York Botanical Garden for comments on a draft of this manuscript. We also thank Alin N. Torres Díaz and Luisa Sandoval of the Botany Lab. of the FES Iztacala-UNAM for their help in the checking of synonymy and the creation of a database. Thanks also to Jefferson Prado and George Yatskievych for critical reviews of the manuscript.

 

Appendix 1

Appendix 2

 

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