# Epiphytism across a megadiverse pteridoflora: Ferns and lycophytes as epiphytes in Peru

Blanca León, Demetria Mondragón, Michael Kessler, Germinal Rouhan, Kenneth R Young, Narda Alarcón, Freddy Peláez Peláez, Joaquina Albán

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Blanca León, Demetria Mondragón, Michael Kessler, Germinal Rouhan, Kenneth R Young, et al. "Epiphytism across a megadiverse pteridoflora: Ferns and lycophytes as epiphytes in Peru." Revista Peruana de Biología, 2026, 33 (1), pp.e31912. 10.15381/rpb.v33i1.31912. mnhn-05532385

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# Epiphytism across a megadiverse pteridoflora: Ferns and lycophytes as epiphytes in Peru

## Epifitismo a través de una pteridoflora megadiversa: helechos y licófitos como epífitos en Perú

**Blanca León** \*1,2,3

https://orcid.org/0000-0001-6307-8639
leon@austin.utexas.edu

**Demetria Mondragón** 4

https://orcid.org/0000-0002-0679-7562
dmondragon@ipn.mx

**Michael Kessler** 5

https://orcid.org/0000-0003-4612-9937
michael.kessler@systbot.uzh.ch

**Germinal Rouhan** 6

https://orcid.org/0000-0002-0751-5352
rouhan@mnhn.fr

**Kenneth R. Young** 1,7

https://orcid.org/0000-0003-0866-1260
kyoung@austin.utexas.edu

**Narda Alarcón** 8

https://orcid.org/0000-0002-6996-1729
nalarcon@unitru.edu.pe

**Freddy Peláez Peláez** 8

https://orcid.org/0000-0001-7053-5885
fpelaez@unitru.edu.pe

**Joaquina Albán-Castillo** 9

https://orcid.org/0000-0003-4104-2912
jalbanc@unmsm.edu.pe

**\*Corresponding author**

1. University of Texas at Austin, Department of Geography and the Environment, U.S.A.

2. University of Texas at Austin, Billy Turner Plant Resources Center, U.S.A.

3. Universidad Nacional Mayor de San Marcos, Facultad de Ciencias Biológicas, Museo de Historia Natural, Departamento de Briología y Pteridología, Lima, Peru.

4. Instituto Politécnico Nacional, Centro interdisciplinario de investigación para el desarrollo integral regional (CIIDIR) unidad Oaxaca, Oaxaca, México CP 71230.

5. University of Zurich, Systematic and Evolutionary Botany, Zurich, Switzerland.

6. Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, EPHE, UA, Paris, France.

7. Universidad Nacional Mayor de San Marcos, Facultad de Ciencias Biológicas, Programa de Doctorado, Lima, Peru.

8. Universidad Nacional de Trujillo, Facultad de Ciencias Biológicas, Trujillo, Peru.

9. Universidad Nacional Mayor de San Marcos, Museo de Historia Natural, Departamento de Etnobotánica y Botánica Económica, Lima, Perú.

**Citación**

León B, Mondragón D, Kessler M, Rouhan G, Young KR, Alarcón N, Peláez Peláez F, Albán-Castillo J. 2026. Epiphytism across a megadiverse pteridoflora: Ferns and lycophytes as epiphytes in Peru. Revista peruana de biología 33(1): e31912 001-016 (Febrero 2026). doi: https://dx.doi.org/10.15381/rpb.v33i1.31912

Presentado: 13/11/2025

Aceptado: 20/02/2026

Publicado online: 28/02/2026

Editor: Leonardo Romero
**Abstract**

Ferns and lycophytes represent the second largest epiphytic group of vascular plants. Here we examined herbaria collection and literature to provide an account of epiphytes for Peru's pteridoflora. We assessed compositional differences related to geography, altitudinal distribution, and vegetation type, along with observations on endemism and conservation. We report in total 521 species of epiphytes, of which 86 are new epiphyte records. These epiphytic ferns and lycophytes represent 35.4% of the total pteridoflora of Peru. We found 32 endemic species among these plants, most of them growing in humid montane forests. We also found regional differences in the composition of this flora, with compositional richness higher in the Eastern Andean slopes, followed by the Lowlands of the Amazon basin. Populations of epiphytic ferns and lycophytes are mostly known from protected areas (82% of all epiphytes), and most of them were recorded from 10 National Parks, whereas 97 species of which 15 are endemics occur in non-protected areas. There are still many challenges for those interested in epiphytism. These challenges include the correct use of the term epiphyte and habit details, incorporating the gametophytic phase of the life cycle of these plants, the biology of interactions, genetics and population studies. All are challenges associated with the continued need to address geographical gaps in knowledge of the epiphytic flora outside of protected sites, and in regions threatened by land-use and landscape changes.

**Resumen**

Los helechos y licófitos representan el segundo grupo más grande de plantas epífitas vasculares. Aquí examinamos colecciones de herbarios y la literatura para proveer un registro de los epífitos en la pteridoflora de Perú. Evaluamos diferencias en la composición relacionadas a la geografía, distribución altitudinal y tipo de vegetación, además de observaciones sobre endemismo y conservación. Reportamos 521 especies de epífitos, de los cuales 86 representan nuevos registros. Los helechos y licófitos epífitos representan el 35.4% del total de la pteridoflora peruana. Encontramos entre estas epífitas, 32 especies endémicas, la mayoría de ellas ocupan el bosque húmedo montano. Hallamos también diferencias regionales en la composición de esta flora, con la riqueza más alta en las laderas de los andes orientales, seguido por la de llanura de la cuenca amazónica. Poblaciones de helechos y licófitos epífitos se conocen mayormente de áreas protegidas (82% de todas las epífitas), y estas provenientes principalmente de 10 Parques Nacionales, mientras que 97 especies incluyendo 15 endemismos se hallan en áreas no protegidas. Reconocemos la persistencia de numerosos retos a los interesados en epifitismo. Estos retos incluyen el empleo correcto del término epífito y detalles del hábito, la incorporación de la fase gametofítica de estas plantas, el examen de la biología de interacciones de los helechos y licófitos epífitos con otros organismos, la inclusión de estudios genéticos y poblacionales. Todos estos retos asociados a la aún necesidad de resolver los vacíos de información geográfica de la flora epífita fuera de áreas protegidas y en regiones amenazadas por cambios tanto en el uso de la tierra como en el paisaje.

**Palabras clave:**

Epifitismo, helechos, licófitos, patrones de distribución, neotrópico, Perú.

**Keywords:**

Epiphytism, ferns, lycophytes, distribution patterns, Neotropics, Peru.

Introduction

In the Neotropics, Peru hosts one of the largest vas-
cular plant floras, together with Brazil, Colombia and
Mexico (Ulloa et al. 2017), supporting its megadiverse
status, and as complemented by striking ecological and
geographical diversity (Rodríguez & Young 2000, MI-
NAM 2019). Similarly, there is a high species richness
of ferns and lycophytes, with Peru's national diversity
levels similar to those of Brazil (León et al. 2022, Flora
e Funga do Brasil 2025), Mexico (Villaseñor 2016), and
Colombia and Ecuador (Morris & Moran 2025). Some of
that diversity is also represented in differences among
plant life form strategies, including the degree and kind
of epiphytism (Madison 1977).

Tropical humid plant communities are often con-
sidered to host numerous epiphyte species (Madison
1977, Taylor et al. 2022), fulfilling important ecologi-
cal roles (Gentry & Dodson 1987; Cardelús et al. 2006;
Watkins & Cardelús 2012; Zotz 2016). Specifically for
ferns and lycophytes, examinations of non-terrestrial
habits also have helped identify evolutionary proces-
ses during the Cretaceous that in part led to the diver-
sification of current diverse fern lineages (Watkins &
Cardelús 2012, Hernández-Rojas et al. 2020, 2021, Jin
et al. 2021). Associated research topics have included
examining effects of environmental shifts in forest ca-
nopies affecting both the gametophytic and sporophytic
stages (Watkins et al. 2009, Watkins & Cardelús 2012), the role of phorophyte hosts affecting epiphyte composition (Francisco et al. 2025), species interactions (e.g. León & Young 2010), and community level studies of distribution patterns (Cardelús et al. 2006) and functional traits (Nitta et al. 2020).

The term epiphyte, however, encompasses a variety of habits, including plants that grow as hemiepiphytes (germinate on the tree and them reach the soil) or those plants that have mixed strategies, that is, are facultatively epiphytic and sometimes are additionally found growing in soil or on other substrates. It is not unusual for inaccurate or imprecise recording of habits in the field that leads to collected herbarium material with label information that obscures ontogenetic changes (Zotz et al. 2021a) and that may cloak the role of epiphytes in community structure (Zotz et al. 2021a). As a result, Zotz (2016), Zotz & Einzmann (2023) and Zotz et al. (2023) worked to redefine terms related to non-terrestrial habits, particularly showing that for ferns and lycophytes inter- and intraspecific variation must be addressed to provide a robust set of data for future applications.

In response to these concerns and opportunities, here we aim to provide an account of the ferns and lycophytes in Peru recognized as epiphytes using the standardized definitions of Zotz and Einzmann (2023). A listing of Peru's pteridoflora was completed over 30 years ago (Tryon & Stolze 1989—1994), with several additions (like Smith et al. 2005, Peláez et al. 2011), and as kept curated by the first author of this article, currently including 1498 taxa (B. León, pers. data). Previously, there was a compilation of 305 epiphytic fern and lycophyte species done in the thesis project of Huaman (2021), and a recent list compiled by Taylor et al. (2022) recorded 488 species attributed to Peru, which formed the nucleus of the current project.

Our objectives are to provide an updated and curated list for Peru of epiphytic ferns and lycophytes. We utilize it to summarize compositional differences related to geography, altitudinal distribution, and vegetation type, along with observations on endemism and conservation. We end by identifying challenges for improving knowledge of epiphytic pteridoflora.

## Material and methods

**Database.** A database of all fern and lycophyte taxa recorded for Peru and managed by B. León in Access was used as a main source to pull records of all species observed as epiphytes, based on herbaria specimens and the literature. This new database was managed in Excel, and included taxonomic information, general and in-country geographic distribution information, altitudinal range, and presence in protected areas. We extracted from Dryad (https://doi.org/10.5061/dryad.kwh70rz46) the supplementary list of all epiphytic vascular plants compiled by Taylor et al. (2022), and selected all ferns and lycophytes in a different table, then this list was sorted by geographical distribution, obtaining a new list of those records attributed to Peru. For each species in that list, we first confirmed its presence in Peru against our database and non-Peruvian herbaria records through PteridoPortal (Rothfels et al. 2025), also using available taxonomic literature, especially for speciose genera like *Elaphoglossum* (e.g. Matos et al. 2019, 2021, 2022; Vasco 2011; Vasco et al. 2009, 2013) and *Hymenophyllum* (Ponce et al. 2017; Gonzatti et al. 2023), two genera recognized to be predominantly epiphytic, plus floristic treatments of neighboring countries such as Bolivia (Kessler & Smith 2018; Kessler et al. 2018; Smith et al. 2018) and Brazil (Prado et al. 2017). We used the classification of PPG-I (2016) with additional updates as recorded in World Flora Online (WFO 2025). For taxonomic status, we used taxonomic treatments published after 2005 (using as the initial date Smith et al. 2005) and complemented these data using Tropicos.

We addressed habit fidelity by reviewing herbarium records from two Peruvian institutions (HUT, USM, herbaria codes following Thiers 2025), US herbaria in PteridoPortal, herbaria and flora websites (Berlin, Brazil, ConoSur), literature, and expertise. We recorded our taxa as 1) holoepiphytes (E_h) for those with most (over 90%) of specimens recorded by collectors as epiphytes, 2) facultative epiphytes (E_f) for those taxa with specimens typically recorded as epiphytes (>50 - <90%) but also with other habits, or 3) accidental epiphytes (E_a) for those taxa with few specimens (<10%) recorded as epiphytes but mostly occurring with other habits. Hemiepiphytes would typically be assessed as facultative epiphytes in this study. That said, there continues to be some ambiguity in habit given the sparseness of some herbarium labels in describing how the collected plant was growing in the field.

**Study area.** Peru's territory was assigned to four main regions: Coast, Western slopes, Eastern slopes and Lowlands (Figure 1). These regions were subdivided by their main hydrological basin, and then by altitude. The coast was defined as the area on the Pacific basin side below 1000 m elevation. Western slopes correspond to the territory on the Pacific basin above 1000 m elevation. Eastern slopes correspond to the territory on the Amazonian basin side above 1000 m elevation. Lowlands here corresponds to the Amazonian territory of Peru below 1000 m elevation. Each region has different ecological and climate conditions with differential diversity patterns (e.g. León et al. 2006), which were also utilized here when discussing distributions. Seasonal dry forests (SDF) occupy both coastal and interandean areas (Linares-Palomino 2004), so we follow here Linares-Palomino et al. (2022) to characterize distributions in Coastal SDFs and Interandean SDFs. Altitudinal range for taxa within Peru was used to analyze regional composition. We also recorded species presence in seven categories of protected sites: National Parks, National Reserves, Historical Sanctuaries, National Sanctuaries, Reserved Zones, Protected Forests and Communal Conservation Areas.
<figure><img src="image_2.png" /><figcaption>**Figure 1.** Study area. Peruvian territory shows four main regions: Coast, Western slopes, Eastern slopes and Lowlands.</figcaption></figure>

## Results

Our data reveals a total of 521 species of ferns and lycophytes in 58 genera and 17 families for Peru's epiphytic ferns and lycophytes. Excluding autonyms, eight varieties (in Hymenophyllaceae, Lycopodiaceae and Polypodiaceae) and two forms (in Dryopteridaceae) could also be recognized, which would then lead to a total of 531 taxa. The number of epiphytic taxa represents 35.4% of Peru's total pteridoflora, currently recognized to include 1498 taxa. We found 48 species included by Taylor et al. (2022) not to be epiphytes for Peru but found either mostly terrestrial or in one case, semiaquatic, in addition to nine species currently treated in synonymy and eight species not known for the country (Suppl. 1).

We found that the most species-rich families (with over 100 species) are Polypodiaceae (216 spp.) and Dryopteridaceae (120 spp.), followed by Hymenophyllaceae (76 spp.) and Aspleniaceae (50 spp.) (see Suppl. 1). Polypodiaceae species richness in Peru was found in 23 genera (out of 67 in the family), of which more than half (14 genera) belong to the subfamily Grammitidoideae,

encompassing 105 species, while nine genera and 111 species belong to the other subfamilies (“polypodioids”) (Suppl. 1). In Polypodiaceae five genera were represented by a single species, while six genera have more than 15 species: *Campyloneurum* (25), *Serpocaulon* (23), *Ceradenia* (22), *Pleopeltis* (21), *Melpomene* (19), and *Microgramma* (18). The second largest family, Dryopteridaceae was represented by five genera (out of 26), of which only *Elaphoglossum* (110) included most of the species. Hymenophyllaceae was represented by seven genera (out of nine) and only two included most species *Hymenophyllum* (44) and *Trichomanes* (18). Aspleniaceae included two genera, and *Asplenium* (47) included over 90% of the epiphytic species.

We report here 86 species of newly identified epiphytes (Table 1), thus updating and expanding Taylor et al. (2022). Most of these novelties are found in Polypodiaceae (28 spp.) and Dryopteridaceae (27 spp.). The genera with most novelties are *Elaphoglossum* (22 spp.) and *Serpocaulon* (8 spp.), and 11 species belonging to seven grammitidoids genera, all of which are groups needing more exploration in the field and study in the herbarium.
<table><caption>**Table 1.** Newly recorded taxa as epiphytes of Peruvian fern and lycophytes, uncited in Taylor et al. 2022.</caption><thead><tr><td>Family</td><td>Especie</td></tr></thead><tbody><tr><td>Aspleniaceae</td><td>Asplenium dissectum Sw.</td></tr><tr><td>Aspleniaceae</td><td>Asplenium drepanophyllum Kunze</td></tr><tr><td>Aspleniaceae</td><td>Asplenium macrurum Mickel & Stolze</td></tr><tr><td>Aspleniaceae</td><td>Asplenium micropaleatum M. Kessler & A.R. Sm.</td></tr><tr><td>Aspleniaceae</td><td>Asplenium monodon Liebm.</td></tr><tr><td>Aspleniaceae</td><td>Asplenium pseudoangustum Stolze</td></tr><tr><td>Aspleniaceae</td><td>Asplenium quitense Hook.</td></tr><tr><td>Aspleniaceae</td><td>Asplenium stuebelianum Hieron.</td></tr><tr><td>Aspleniaceae</td><td>Asplenium vomeriforme Hook.</td></tr><tr><td>Aspleniaceae</td><td>Hymenasplenium delitescens (Maxon) L. Regalado & C. Prada</td></tr><tr><td>Aspleniaceae</td><td>Hymenasplenium triquetrum (N. Murak. & R.C. Moran) L. Regalado & Prada</td></tr><tr><td>Athyriaceae</td><td>Diplazium alienum (Mett.) Hieron.</td></tr><tr><td>Blechnaceae</td><td>Lomaridium fuscosquamosum (A. Rojas) Gasper & V.A.O. Dittrich</td></tr><tr><td>Cyatheaceae</td><td>Cyathea gracilis Griseb.</td></tr><tr><td>Dryopteridaceae</td><td>Cyclodium meniscioides (Willd.) C. Presl</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum acutifolium Rosenst.</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum chloodes Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum curvans (Kunze) A. Rojas</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum dendricola (Baker) Christ</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum dichroum Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum guamanianum (Sodiro) C. Chr.</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum hikenii (Sodiro) C. Chr.</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum inaequalifolium (Jenman) C. Chr.</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum latevagans Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum lawyerae Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum leprosum (Kuhn) Christ</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum madidiense M. Kessler & Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum mickeliorum F.B. Matos & R.C. Moran</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum moyeri Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum palorense Rosenst.</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum paultonii Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum potamogeton Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum punae Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum rosenstockii Christ ex Rosenst.</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum vascoae F.B. Matos & R.C. Moran</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum versatile (Sodiro) F.B. Matos</td></tr><tr><td>Dryopteridaceae</td><td>Elaphoglossum vittarioides Mickel</td></tr><tr><td>Dryopteridaceae</td><td>Polybotrya glandulosa Kunth</td></tr><tr><td>Dryopteridaceae</td><td>Polybotrya hickeyi R.C. Moran</td></tr><tr><td>Dryopteridaceae</td><td>Polybotrya osmundacea Willd.</td></tr><tr><td>Dryopteridaceae</td><td>Polybotrya pubens Mart.</td></tr><tr><td>Hymenophyllaceae</td><td>Hymenophyllum angustum Bosch</td></tr><tr><td>Hymenophyllaceae</td><td>Hymenophyllum axillare Sw.</td></tr><tr><td>Hymenophyllaceae</td><td>Hymenophyllum interruptum Kunze</td></tr><tr><td>Hymenophyllaceae</td><td>Hymenophyllum simplex C.V. Morton</td></tr><tr><td>Hymenophyllaceae</td><td>Hymenophyllum tarapotense Stolze</td></tr><tr><td>Hymenophyllaceae</td><td>Trichomanes cellulosum Klotzsch</td></tr><tr><td>Hymenophyllaceae</td><td>Trichomanes diversifrons (Bory) Mett. ex Sadeb.</td></tr></tbody></table>
<table><thead><tr><td>Family</td><td>Especie</td></tr></thead><tbody><tr><td>Lindsaeaceae</td><td>Lindsaea taeniata K.U. Kramer</td></tr><tr><td>Lomariopsidaceae</td><td>Lomariopsis prieuriana Fée</td></tr><tr><td>Lycopodiaceae</td><td>Phlegmariurus callitrichifolius (Mett.) B. Øllg.</td></tr><tr><td>Lycopodiaceae</td><td>Phlegmariurus capillaris (Sodiro) B. Øllg.</td></tr><tr><td>Lycopodiaceae</td><td>Phlegmariurus pruinosus (Herter) B. Øllg.</td></tr><tr><td>Nephrolepidaceae</td><td>Nephrolepis undulata (Afzel ex Sw.) J. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Alansmia diaphana (Mogul & M. Kessler) Mogul & M. Kessler</td></tr><tr><td>Polypodiaceae</td><td>Ascogrammitis anfractuosa (Kunze ex Klotzsch) Sundue</td></tr><tr><td>Polypodiaceae</td><td>Ascogrammitis pichinchensis (Hierон.) Sundue</td></tr><tr><td>Polypodiaceae</td><td>Campyloneurum atrosquamatum Labiak, B. León & R.C. Moran</td></tr><tr><td>Polypodiaceae</td><td>Campyloneurum decurrens (Raddi) C. Presl</td></tr><tr><td>Polypodiaceae</td><td>Ceradenia kalbreyeri (Baker) L.E. Bishop</td></tr><tr><td>Polypodiaceae</td><td>Ceradenia similis M. Kessler & A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Ceradenia spixiana (Mart. ex Mett.) L.E. Bishop</td></tr><tr><td>Polypodiaceae</td><td>Grammitis setosora M. Kessler & A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Lellingeria suspensa (L.) A.R. Sm. & R.C. Moran</td></tr><tr><td>Polypodiaceae</td><td>Microgramma nana (Liebm.) T. Almeida</td></tr><tr><td>Polypodiaceae</td><td>Moranopteris aphelolepis (C.V. Morton) R.Y. Hirai & J. Prado</td></tr><tr><td>Polypodiaceae</td><td>Moranopteris williamsii (Maxon) R.Y. Hirai & J. Prado</td></tr><tr><td>Polypodiaceae</td><td>Niphidium macbridei Lellinger</td></tr><tr><td>Polypodiaceae</td><td>Phlebodium aureum (L.) J. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Phlebodium pseudoaureum (Cav.) Lellinger</td></tr><tr><td>Polypodiaceae</td><td>Pleopeltis × leucospora (Klotzsch) T. Moore</td></tr><tr><td>Polypodiaceae</td><td>Pleopeltis masafuerae (Phil.) de la Sota</td></tr><tr><td>Polypodiaceae</td><td>Pleopeltis tweedieana (Hook.) A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Serpocaulon articulatum (C. Presl) Schwartsb. & A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Serpocaulon attenuatum (Humb. & Bonpl. ex Willd.) A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Serpocaulon concolorum (M. Kessler & A.R. Sm.) A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Serpocaulon funckii (Mett.) A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Serpocaulon latipes (Langsd. & Fisch.) A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Serpocaulon latissimum (R.C. Moran & B. Øllg.) A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Serpocaulon nanegalense (Sodiro) A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Serpocaulon psychotrium Mostacero, D. Sanín & A.R. Sm.</td></tr><tr><td>Polypodiaceae</td><td>Terpsichore chrysleri (Copel.) A.R. Sm.</td></tr><tr><td>Pteridaceae</td><td>Pityrogramma calomelanos (L.) Link</td></tr><tr><td>Pteridaceae</td><td>Pteris biaurita L.</td></tr><tr><td>Thelypteridaceae</td><td>Goniopteris erythrothrix (A.R. Sm.) Salino & T.E. Almeida</td></tr><tr><td>Thelypteridaceae</td><td>Pelazoneuron abruptum (C. Presl) A.R. Sm. & S.E. Fawc.</td></tr></tbody></table>

**Habits.** Species that are facultatively epiphytic dominated Peru's pteridoflora as identification of habit fidelity revealed 293 facultative taxa, 205 taxa as holoepiphytes, and 33 that are considered accidentals based on information on herbarium labels.

The four largest genera, *Asplenium* (47 epiphytes/61 total in Peru), *Elaphoglossum* (110/154), *Hymenophyllum* (46/48) and *Phlegmariurus* (24/55), showed variability in habit preference. For example, *Phlegmariurus* is predominantly recorded as an holoepiphyte in Peru and

rarely grows in other situations, whereas *Elaphoglossum* species are often facultatively epiphytic, and are also often found in humid soils or rocky substrates. Another four genera with over 20 species, *Campyloneurum*, *Ceradenia*, *Pleopeltis* and *Serpocaulon* (Table 2), showed also variation in habit characteristics from strict epiphytism to habit flexibility (including terrestrial and rupicolous habits). The newly identified epiphytes were mostly facultative (49 species), followed by holoepiphytes (24), and accidentals (13), (see Figure 2).
<table><caption>**Table 2.** Habit specialism among genera with the highest records of species among Peruvian epiphytic fern and lycophytes. E_h: holoepiphytes, E_f: facultative, E_a: accidentals.</caption><thead><tr><th>Genera*</th><th>E_h</th><th>E_f</th><th>E_a</th></tr></thead><tbody><tr><td>Asplenium</td><td>6</td><td>36</td><td>5</td></tr><tr><td>Elaphoglossum</td><td>52</td><td>58</td><td>0</td></tr><tr><td>Hymenophyllum</td><td>22</td><td>22</td><td>0</td></tr><tr><td>Phlegmariurus</td><td>19</td><td>7</td><td>0</td></tr><tr><td>Campyloneurum</td><td>8</td><td>14</td><td>3</td></tr><tr><td>Serpocaulon</td><td>1</td><td>22</td><td>0</td></tr><tr><td>Ceradenia</td><td>11</td><td>11</td><td>0</td></tr><tr><td>Pleopeltis</td><td>6</td><td>12</td><td>3</td></tr></tbody></table>

<figure><img src="image_3.png" /><figcaption>**Figure 2.** New species records of Peruvian ferns and lycophytes as epiphytes.</figcaption></figure>

Thirty-four facultative species were found to be labeled as “hemiepiphytes”. Most of these epiphytes occur in forests at low elevations and extend upwards in forests towards the lower limits of the Eastern Andean slope region. These species belong to seven families and 12

genera (Suppl. 1). One family includes most species, Polypodiaceae (21 spp.). Large genera labeled as “hemiepiphytes” include *Serpocaulon* with 17 spp., and *Polybotrya* with 3 spp. On the other hand, *Lomariopsis* with two facultative species, also includes three species that are mostly labeled as “hemiepiphytes” (*L. japurensis* (Mart.) J.Sm., *L. latipinna* Stolze, and *L. nigropaleata* Holttum), and therefore not included here.

**Distributions.** The regional distribution of epiphytism within Peru reveals differences in richness and composition (Table 3). Only nine species are known to occur in three of the four regions recognized here; none were from all regions. The Coastal region includes isolated patches of forested areas, here epiphytes are found in three families, Aspleniaceae with the two genera *Asplenium* and *Hymenasplenium*, and two species, Polypodiaceae with four genera (*Microgramma*, *Niphidium*, *Pleopeltis* and *Serpocaulon*) with 10 species, and Pteridaceae with one genus (*Pityrogramma*). Northern coastal Peru vegetation is dominated by Seasonal Dry Forests and includes seven epiphytic species with one restricted to that region, *Pleopeltis hookeri* A.R. Sm., also known from similar vegetation in western Ecuador, and another, *P. balaonense* (Hieron.) A.R. Sm. extends its distribution to the northwestern Andean slopes in Peru. One species, *Pleopeltis masafuerae* (Phil.) de la Sota is only known from fog-oasis vegetation (lomas) on the central and southern coast, growing on *Tara spinosa* (Molina) Briton & Rose and *Capparidastrum petiolare* (Kunth) Hutch.

The Western Andean slope region has fragmented Andean forests. This region includes 63 species belonging to 20 genera in seven families, three of which Polypodiaceae (35 spp.), Dryopteridaceae (10 spp.) and Aspleniaceae (9 spp.) represent over 85% of the region's total (Table 3). There are no species limited to this region. It shares 61 species with the Eastern Andean slope region. All species except four are recorded as facultative.

<table><caption>**Table 3.** Regional composition and richness.</caption><caption>WESTERN COMPOSITION</caption><thead><tr><th>Family</th><th>genera</th><th>species</th></tr></thead><tbody><tr><td>Aspleniaceae</td><td>1</td><td>9</td></tr><tr><td>Dryopteridaceae</td><td>1</td><td>10</td></tr><tr><td>Hymenophyllaceae</td><td>2</td><td>2</td></tr><tr><td>Lycopodiaceae</td><td>1</td><td>2</td></tr><tr><td>Nephrolepidaceae</td><td>1</td><td>2</td></tr><tr><td>Polypodiaceae</td><td>11</td><td>35</td></tr><tr><td>Pteridaceae</td><td>3</td><td>3</td></tr><tr><td>7 families</td><td>20 g</td><td>63</td></tr></tbody></table>

<table><caption>COASTAL COMPOSITION</caption><thead><tr><th>Family</th><th>genera</th><th>species</th></tr></thead><tbody><tr><td>Aspleniaceae</td><td>2</td><td>2</td></tr><tr><td>Polypodiaceae</td><td>4</td><td>10</td></tr><tr><td>Pteridaceae</td><td>1</td><td>1</td></tr><tr><td><strong>3 families</strong></td><td><strong>7 g</strong></td><td><strong>13</strong></td></tr></tbody></table>

<table><caption>EASTERN COMPOSITION</caption><thead><tr><th>Family</th><th>genera</th><th>species</th></tr></thead><tbody><tr><td>Aspleniaceae</td><td>2</td><td>42</td></tr><tr><td>Athyriaceae</td><td>1</td><td>1</td></tr><tr><td>Blechnaceae</td><td>2</td><td>6</td></tr><tr><td>Cyatheaceae</td><td>1</td><td>1</td></tr><tr><td>Dryopteridaceae</td><td>4</td><td>103</td></tr><tr><td>Hymenophyllaceae</td><td>7</td><td>67</td></tr><tr><td>Lomariopsidaceae</td><td>1</td><td>1</td></tr><tr><td><strong>Lycopodiaceae</strong></td><td><strong>1</strong></td><td><strong>21</strong></td></tr><tr><td>Nephrolepidaceae</td><td>1</td><td>4</td></tr><tr><td>Oleandraceae</td><td>1</td><td>3</td></tr><tr><td>Ophioglossaceae</td><td>1</td><td>1</td></tr><tr><td><strong>Polypodiaceae</strong></td><td><strong>22</strong></td><td><strong>193</strong></td></tr><tr><td>Pteridaceae</td><td>5</td><td>12</td></tr><tr><td>Selaginellaceae</td><td>1</td><td>2</td></tr><tr><td>Thelypteridaceae</td><td>2</td><td>2</td></tr><tr><td><strong>15 families</strong></td><td><strong>52 g</strong></td><td><strong>459</strong></td></tr></tbody></table>

<table><caption>LOWLAND COMPOSITION</caption><thead><tr><th>Family</th><th>genera</th><th>species</th></tr></thead><tbody><tr><td><strong>Aspleniaceae</strong></td><td>2</td><td>34</td></tr><tr><td>Blechnaceae</td><td>1</td><td>1</td></tr><tr><td>Cyatheaceae</td><td>1</td><td>1</td></tr><tr><td><strong>Dryopteridaceae</strong></td><td>4</td><td>39</td></tr><tr><td><strong>Hymenophyllaceae</strong></td><td>7</td><td>43</td></tr><tr><td>Lindsaeaceae</td><td>1</td><td>1</td></tr><tr><td>Lomariopsidaceae</td><td>1</td><td>1</td></tr><tr><td>Lycopodiaceae</td><td>1</td><td>4</td></tr><tr><td>Nephrolepidaceae</td><td>1</td><td>7</td></tr><tr><td>Oleandraceae</td><td>1</td><td>2</td></tr><tr><td><strong>Polypodiaceae</strong></td><td>15</td><td>51</td></tr><tr><td>Psilotaceae</td><td>1</td><td>1</td></tr><tr><td><strong>Pteridaceae</strong></td><td>6</td><td>10</td></tr><tr><td>Selaginellaceae</td><td>1</td><td>3</td></tr><tr><td>Thelypteridaceae</td><td>1</td><td>1</td></tr><tr><td>15 families</td><td>44 g</td><td>199</td></tr></tbody></table>

<footnote>*Note. The first four genera are the richest, and also represent those exa- mined by Zotz & Einzmann 2023, while another four are selected by having more than 20 spp.</footnote>
The Eastern Andean slope region includes most of the humid montane forests in the country and small pockets of interandean and Seasonal Dry Forests. It is also by far the richest species region with 459 species in 52 genera and 15 families. There are 269 species only known from this region. Five families include 20 or more species, Polypodiaceae (193 spp.), Dryopteridaceae (103), Hymenophyllaceae (67), Aspleniaceae (42) and Lycopodiaceae (21) (Table 3). The genera with more than 20 species include *Elaphoglossum* (95), *Asplenium* (39), *Hymenophyllum* (37) and *Campyloneurum* (23), while *Phlegmariurus* and *Serpocaulon* are represented by 20 species.

The Lowland region encompasses 199 species in 44 genera and in 15 families. There are 58 species only known from this region, and 10 species limited to elevations below 500 m. The richest family is Polypodiaceae (51 spp.) followed by Hymenophyllaceae (43 spp.), Dryopteridaceae (39 spp.) and Aspleniaceae (34 spp.) (Table 3). Species-rich genera include *Asplenium* (32) and *Elaphoglossum* (31), then *Hymenophyllum* (18), *Microgramma* (13) and *Trichomanes* (12). This region and the Eastern Andean slope region share 141 species that represent over 70% of the epiphytic ferns and lycophytes found below 1000 m elevation.

Even high elevation forests have epiphytes in Peru, for example two species, *Elaphoglossum madidiense* M. Kessler & Mickel (Dryopteridaceae) and *Lellingeria flexibilis* Labiak (Polypodiaceae), are found in upper montane humid forests (Suppl.1). There are also three other members of the Polypodiaceae that reach altitudes over 4200 m elevation from *Polylepis* forests, *Adetogramma chrysolepis* (Hook.) T. Almeida, *Melpomene personata* Lehnert and *M. peruviana* (Desc.) A.R. Sm. & R.C. Moran (Suppl. 1). Andean forests that correspond to inter-Andean Seasonal Dry Forests include two Polypodiaceae, *Ascogrammitis athyrioides* (Hook.) Sundue and *Ceradenia herrerae* (Copel.) L.E. Bishop known from altitudes above 2000 m elevation.

The distribution by departments shows that those located on the Eastern slope region have high species richness (See Suppl. 1), each one harboring over 59% of all epiphytes: Pasco (358 spp.), Cusco (339 spp.), Amazonas (318 spp.) and San Martin (314 spp.); together they share 155 species (29% of the total epiphyte species richness).

Seventy-five percent of total epiphytic taxa recorded here are shared with two neighboring countries, Bolivia and Ecuador, while 58% are shared with Colombia and 35% with Brazil. Most taxa shared with Bolivia and Ecuador have wide elevational ranges, and they occupy humid montane forest on the Eastern Andean slopes.

**Conservation.** Most species (82%) are found in one or more protected areas. Populations of a total of 381 species have been documented in ten National Parks (from north to south): Ichigkat Muja - Cordillera del Cóndor, Cutervo, Huascarán, Cordillera Azul, Río Abiseo, Tingo María, Yanachaga-Chemillén, Otishi, Bahaja-Sonene, and Manu. These protected areas have provided habitats for most records of epiphytes (Table 4).

<table><caption>**Table 4.** Presence of epiphyte ferns and lycophytes in seven types of Protected Areas of Peru.</caption><thead><tr><td>PROTECTED SITES</td><td>Number of species</td></tr></thead><tbody><tr><td>National Parks</td><td>381</td></tr><tr><td>National Reserves</td><td>43</td></tr><tr><td>Historical Sanctuary</td><td>59</td></tr><tr><td>National Sanctuaries</td><td>23</td></tr><tr><td>Reserve Zones</td><td>11</td></tr><tr><td>Protected Forests</td><td>3</td></tr><tr><td>Community Protected Zone</td><td>1</td></tr></tbody></table>

The Historical Sanctuary, Machu Picchu includes more epiphyte species than other National Reserves, and National Sanctuaries (Table 4).

However, 97 species, of which 15 are endemics, in seven families (Suppl. 1), Aspleniaceae (6 spp.), Blechnaceae (1 sp.), Dryopteridaceae (25 spp.), Hymenophyllaceae (17 spp.), Lycopodiaceae (5 spp.), Polypodiaceae (40 spp.), Pteridaceae (1 sp.) and Selaginellaceae (1 sp.) have not yet been recorded from a protected site (Suppl. 1). Four of these families include 50 species recognized as holoepiphytes: Lycopodiaceae has all five species as such, while Polypodiaceae includes 22, Dryopteridaceae includes 13 and Hymenophyllaceae includes 10. They presumably would have no formal protection from effects of land use or land cover change.

In terms of endemism, thirty-two species in five families, Aspleniaceae, Dryopteridaceae, Hymenophyllaceae, Polypodiaceae and Thelypteridaceae are only known from Peru (Table 5), and 14 are known from only one or two localities. Seventeen of these species are found in protected areas. Twenty-three endemic species are recognized as holoepiphytes, eight are facultative and one, *Niphidium macbridei* Lellinger, occurs accidentally as an epiphyte. Except for *Elaphoglossum lawyerae* Michel, *Hymenophyllum adiantoides* Bosch and *H. tarapotense* Stolze known from below 1000 m elevation (Lowland region), most restricted species are found in humid montane forests in the Eastern Andean slope region.

## Discussion

Epiphytic ferns and lycophytes significantly contribute to species diversity and composition in other regional and local floras (e.g., Gentry & Dodson 1987), as they do for Peru's flora. Undoubtedly these plants are important components of the epiphyte community in tropical South America both in humid and dry vegetation types (Carmona-Higuita et al. 2024; Ramos et al. 2025).

We found that by using a combination of taxonomic expertise with local and global herbaria collections, we could provide a better estimate of species richness of epiphyte ferns and lycophytes for Peru's flora. This contribution then helps to update global efforts to document this habit as done by Zotz et al. (2021 b) through the EpiList1.0 and helps eliminate the information gap noted in recent phytogeographical endeavors (Quaresma et al. 2022; Ramos et al., 2025).
<table><caption>**Table 5.** Epiphyte ferns restricted in distribution to Peru. E_f= facultative; E_h=holoepiphytes; E_a= accidental.</caption><thead><tr><th>Habit</th><th>Family</th><th>Name</th><th>Altitude Minimum</th><th>Altitude Maximum</th><th>Departments</th></tr></thead><tbody><tr><td>E_h</td><td>Aspleniaceae</td><td>Asplenium eutecnum A.R. Sm.</td><td>250</td><td>500</td><td>AM</td></tr><tr><td>E_h</td><td>Dryopteridaceae</td><td>Elaphoglossum craspedotum Copel.</td><td>1150</td><td>1380</td><td>HU, PA</td></tr><tr><td>E_f</td><td>Dryopteridaceae</td><td>Elaphoglossum dichroum Mickel*</td><td>3000</td><td>3410</td><td>PA, SM</td></tr><tr><td>E_h</td><td>Dryopteridaceae</td><td>Elaphoglossum lawyerae Mickel</td><td>650</td><td>900</td><td>PA</td></tr><tr><td>E_f</td><td>Dryopteridaceae</td><td>Elaphoglossum leprosum (Kuhn) Christ</td><td>2090</td><td>3950</td><td>AM, CU, HU, JU, LL, SM</td></tr><tr><td>E_f</td><td>Dryopteridaceae</td><td>Elaphoglossum nickeliorum F.B. Matos &amp; R.C. Moran</td><td>1700</td><td>2900</td><td>AM, CA, CU, PA</td></tr><tr><td>E_h</td><td>Dryopteridaceae</td><td>Elaphoglossum moyeri Mickel</td><td>2200</td><td>2500</td><td>PA</td></tr><tr><td>E_h</td><td>Dryopteridaceae</td><td>Elaphoglossum oculatum Mickel*</td><td>1170</td><td>3100</td><td>PI</td></tr><tr><td>E_h</td><td>Dryopteridaceae</td><td>Elaphoglossum paultonii Mickel</td><td>2100</td><td>2100</td><td>CU</td></tr><tr><td>E_h</td><td>Dryopteridaceae</td><td>Elaphoglossum potamogeton Mickel</td><td>1720</td><td>1850</td><td>JU</td></tr><tr><td>E_h</td><td>Dryopteridaceae</td><td>Elaphoglossum punae Mickel</td><td>3400</td><td>3600</td><td>AY</td></tr><tr><td>E_f</td><td>Dryopteridaceae</td><td>Elaphoglossum vittarioides Mickel</td><td>1150</td><td>2900</td><td>CU, JU, PA</td></tr><tr><td>E_f</td><td>Hymenophyllaceae</td><td>Hymenophyllum adiantoides Bosch</td><td>800</td><td>800</td><td>SM</td></tr><tr><td>E_h</td><td>Hymenophyllaceae</td><td>Hymenophyllum crispum var. bipinnatisectum C.V. Morton</td><td>2400</td><td>3000</td><td>CU</td></tr><tr><td>E_h</td><td>Hymenophyllaceae</td><td>Hymenophyllum lamellatum Stolze</td><td>2550</td><td>3000</td><td>CU, HU, JU, PA, PU</td></tr><tr><td>E_f</td><td>Hymenophyllaceae</td><td>Hymenophyllum mirificum C.V. Morton</td><td>2800</td><td>3650</td><td>CU, JU</td></tr><tr><td>E_h</td><td>Hymenophyllaceae</td><td>Hymenophyllum molle C.V. Morton</td><td>2200</td><td>3600</td><td>CU, JU</td></tr><tr><td>E_h</td><td>Hymenophyllaceae</td><td>Hymenophyllum simplex C.V. Morton</td><td>800</td><td>2000</td><td>CA, SM</td></tr><tr><td>E_h</td><td>Hymenophyllaceae</td><td>Hymenophyllum tarapotense Stolze</td><td>800</td><td>800</td><td>SM</td></tr><tr><td>E_h</td><td>Hymenophyllaceae</td><td>Hymenophyllum trichophyllum var. bluesii C.V. Morton</td><td>2800</td><td>3350</td><td>CA, CU, JU, SM</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Ascogrammitis oxapampensis Sundue</td><td>2400</td><td>3100</td><td>AM, PA, SM</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Ceradenia herrerae (Copel.) L.E. Bishop</td><td>1200</td><td>3000</td><td>CU</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Ceradenia longipinnata (Copel.) L.E. Bishop</td><td>2750</td><td>3250</td><td>CU</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Ceradenia phalacron (Stolze) A.R. Sm.</td><td>1800</td><td>2300</td><td>CU</td></tr><tr><td>E_f</td><td>Polypodiaceae</td><td>Ceradenia praeclara L.E. Bishop</td><td>3150</td><td>3150</td><td>CU, PA</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Lellingeria amplisora Labiak</td><td>1950</td><td>1950</td><td>AM</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Lellingeria flexibilis Labiak</td><td>3600</td><td>3740</td><td>CU</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Microgramma fosteri B. León &amp; H. Beltrán</td><td>1000</td><td>1300</td><td>LO, UC</td></tr><tr><td>E_a</td><td>Polypodiaceae</td><td>Niphidium macbridei Lellinger</td><td>1074</td><td>3600</td><td>AP, CA, CU, HU, JU, LL, PA, SM</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Pleopeltis coenosora R.C. Moran</td><td>1734</td><td>2020</td><td>CA, JU, PA</td></tr><tr><td>E_h</td><td>Polypodiaceae</td><td>Terpsichore bipinnata (Stolze) A.R. Sm.</td><td>3150</td><td>4100</td><td>CU, JU</td></tr><tr><td>E_f</td><td>Thelypteridaceae</td><td>Goniopteris erythrothrix (A.R. Sm.) Salino &amp; T.E. Almeida</td><td>2150</td><td>2250</td><td>AM</td></tr></tbody></table>

Our findings also show that 35.4% of Peru's fern and lycophyte flora occur as epiphytes in a diverse array of forests under ecological conditions of wide range of humidity and temperature. As with other Neotropical epiphytic floras, the Polypodiaceae is the dominant family for number of species, with grammitidoids and polypodioids being important elements (Jiménez-López et al. 2020). This composition of Polypodiaceae reflects the probable phylogenetic legacy of the lineages of these plants with diversification events associated with habitat-linked conditions during the Cenozoic (e.g. Sundue et al. 2015). This condition could also be applied to some members of the Dryopteridaceae (Zuo et al. 2025), particularly to *Elaphoglossum*, a genus widely distributed worldwide in wet montane forests and with several traits in both sporophyte and gametophyte stage associated

with epiphytism (Rouhan et al. 2004). It is also the most species-rich epiphytic genus for Peru's flora.

The main reason for recording epiphytic flora originates with ecological research documenting vascular plant composition, a condition that also applies to Peru with two publications including ferns and lycophytes in lowland sites below 1000 m (Peláez et al. 2019, Quinteros-Gómez et al. 2024), and another two in highland localities above 2000 m (Young & León 1991b, Acuña-Tarazona et al. 2022). From these studies, the same epiphytic rich family at the country level, Polypodiaceae, is represented in all sites, and among epiphytic rich genera, *Asplenium* is shared among all sites. As noted by Sylvester et al. (2014), epiphytes can be found growing higher in Peru than anywhere else in the world.

<footnote>* sensu Vasco 2011</footnote>
## Regional geographical features in terms of taxonomic composition and altitudinal distribution

The flora of the Americas (Ulloa Ulloa et al. 2017) reveals that the Neotropics encompass the largest number of vascular plant species, with an especially strong floristic affinity among three Andean tropical countries Colombia, Ecuador, and Peru. In this context, the composition of epiphytic ferns and lycophytes follows a similar pattern, as Peru's epiphyte fern and lycophytes composition share more similarities to those of Ecuador and Bolivia, their two closest neighboring countries. This pattern in turn is due to the role of the Andean slopes in sharing a common geological and ecological history, and with the Eastern Andean slopes having the largest tracts of humid montane forests (Young & León 1999; Carmona-Higuita et al. 2025), serving as corridors for these spore-bearing organisms. In contrast, Seasonal Dry Forests in the coastal Pacific basin from northwestern Peru to southwestern Ecuador, have a comparatively depauperate fern composition, most of which are widely distributed species (Svenson 1946).

The Andes mountains in Peru's territory provides the main setting for species richness, a character already underlined for ferns and lycophytes in general (Weigand et al. 2020; Suissa et al. 2021). Three to five families dominate mesic and humid forests respectively. We found that mesic environments occurring in Inter-Andean drier valleys and along the Western slopes, with fragmented forests, house ferns and lycophytes that are, except for two species, a subset of the epiphytic flora of the more humid Eastern Andean forests. We also document that for the Eastern Andean slopes and Lowland regions, four families (Polypodiaceae, Dryopteridaceae, Hymenophyllaceae, and Aspleniaceae) encompass most of the species richness, with additional contributions from Lycopodiaceae in the Eastern Andes and Pteridaceae for the Lowland region.

The floristic connection of montane and lowland forests has previously been recognized to occur at the altitude of 1000 to 1500 m (Gentry 1992; Young 1992; Young et al. 2007) and it may reflect the history of forest evolution, environmental heterogeneity and complex Andean orogeny along the Andean foothills in the Amazon basin. However, more work is needed to document patterns of distribution along environmental gradients, as for example the expected hump-shaped pattern of altitudinal distribution (Krömer et al. 2005) along other types of gradients that requires data in abundance (Kessler & Kluge 2022), and the shifts in composition along such gradients (e.g. Kluge et al. 2008). Similarities in species composition occur among epiphytic floras from neighboring biogeographic domains and regions (Ramos et al. 2025), which would allow for further regional comparisons.

## Conservation and geographically restricted taxa

The richness of fern and lycophyte endemic species is defined by the presence of the Andes in conjunction with its ecological complexity (e.g. Suissa et al. 2021). Relatively few ferns and lycophytes are restricted to Peru (León et al. 2006) and currently these species represent

about 9% of the known Peru's pteridoflora, although the tropical Andes is considered to encompass 33% of endemic ferns (Suissa et al. 2021). We found for Peru that endemic epiphytes represent almost 6%. All except three species occupy forests along the Eastern Andean slopes, suggesting once again the importance of humid montane forests for diversity in recently diversified clades (e.g. Sundue et al. 2015; Testo et al. 2018).

Conservation efforts in Peru mostly relate to the formal protection of sites through a system of 10 national categories (SERNANP 2025). For ferns and lycophytes in Peru, the geographic distribution of over 57% of the species includes their recording in sites within one or more protected areas, while for epiphytes, although we only accounted for seven categories, their potential protection to their populations reaches around 82%. These high values, along with the lower levels of endemism compared to terrestrial species, confirm that epiphytic fern and lycophyte species tend to be more widespread than their terrestrial counterparts (Kessler 2000, 2002; Kluge & Kessler 2006).

We found a strong bias towards collecting epiphytes within National Parks that reflect legacies of institutional efforts to examine humid montane forests in those protected sites (Suppl. 1). These findings corroborate the recent evaluation of vascular epiphytes conservation showing, as in our case, that most epiphytic species have been recorded within a protected site (Lucas et al. 2025). However, sites outside protected areas have endemicity and rarity, with the latter represented by those 43.75% of all endemic epiphytic fern and lycophyte species having narrow geographical ranges from one or two locations. Efforts for formally conserving sites for epiphytic species in general face a myriad of difficulties related to habitat quality, environmental fluctuations, and anthropogenic driven changes, as noted for the montane humid forests of the Eastern Andes (Young 1992; Young & León 1999), and to those mesic forests in the Western Andes (Weigend et al. 2005; Arroyo et al. 2008), conditions shared with other Neotropical domains that hereby call the attention to a higher risk for epiphytic populations (Carmona-Higuita et al. 2024).

## Challenges to the study of epiphytism

There are many challenges for having a more definitive record of the epiphytic fern and lycophytes of Peru, since few studies document this habit (Quaresma et al. 2022). These challenges stem from the disparity in recording the epiphytic habit, and particularly in the scarcity of collections targeted at species with non-terrestrial habits, and the limited documentation of all stages of the fern life cycle.

Our findings indicate that over 55% of all fern and lycophyte species listed here are scored as facultative, a value that also appears to be reflected in studies that combine the recording of all kinds of habits (e.g. Ceballos 2023; Acuña-Tarazona et al. 2022). Plant collections may provide information about the habit variability of a species; however, individual records may not consider
the stage of the development of individuals especially for fern sporophytes with long-creeping stems that may hide hemiepiphytism (Watts et al. 2019) or a climber creating inconsistencies in recording of habit (e.g. Hoeber & Zotz 2022). An example can be found in the most species-rich genus *Elaphoglossum* with 71% of all Peruvian species reported as epiphytes and 52% of those epiphyte species found by us to be variable in habitat preferences and habit representation. For Peru's fern flora this finding emphasizes the need for observations of the complete fern life cycle development to assess growth habit and to contribute to the understanding of the evolution of fern epiphytism (Nitta & Epps 2009, Fawcett & Sundue 2016, Lagomarsino et al. 2019).

Hemiepiphytism is currently a topic of interest (Watts et al. 2019, Sundue & Maraia 2024) aimed to clarify the development and evolution of growth habit among ferns (Testo & Sundue 2014), but which requires more detailed information on those processes both in the field and in the laboratory. Those species considered as hemiepiphytes for Peru, but not in the EpiList or here in this work, would be considered as "root climbers" (Canestraro et al. 2014, Watts et al. 2019) since the gametophyte stage is terrestrial and then the sporophyte stage shifts to a climbing habit as was recorded for *Polybotrya pubens* Mart. (Young & León 1991a).

Peru's vascular flora was assessed by Ondo et al. (2024) for gaps in taxonomic descriptions and geolocation of collections providing insights in these Wallacean and Linnean shortfalls, a condition that extends to epiphytes as well. However, the role of local herbaria and fieldwork for the epiphytic flora should be emphasized to provide a more refined species composition and for better conservation assessments, as was done for other vascular plants (Delves et al. 2024).

The largest families and genera represented by the epiphyte fern and lycophytes are also in need of an update in their taxonomy, and their species distributions to be assessed with other Neotropical collections in a more integrative manner. New phylogenetic studies also indicate the presence of species complexes that may include cryptic taxa, as shown for *Phlegmariurus* (Testo et al. 2018), a genus with 47% of epiphyte species in Peru. Some of the forms found in this study may include cryptic taxa. New taxonomic circumscriptions also reveal the importance of detailed assessment of the epiphytic composition, as shown by the case of *Elaphoglossum* (Vasco 2011, Matos et al. 2019, 2021, 2022).

Epiphytism continues to be a source of innovative research from community level studies (Parra-Sánchez & Edwards 2024), and in terms of functional traits and phylogenetic approaches (Jin et al. 2021, Nitta et al. 2020). There is a need for further studies to document patterns of distribution from multiple perspectives for humid montane floras as noted by Young (1992). We also recognize the need for a more comprehensive approach to understand the non-biological factors and intrinsic qualities of epiphyte species in different life stages and evaluating traits within a phylogenetic frame (Nagalingum et al. 2015, Nitta

et al. 2020). As suggested by Luz et al. (2023) a priority should also be continued systematization of information documenting richness and distribution.

## Conclusions

As recorded here, the 521 fern and lycophyte epiphytes represent 35% of the total pteridoflora known for Peru. Regional differences documented here show that epiphytism is concentrated in humid montane forests. Biogeographical links to other Neotropical floras emphasize the importance of the Andes as a source of connectivity through mountain humid forests whose elevational belts cross into neighboring countries. Most epiphyte ferns and lycophytes are known from National Parks in Peru, and endemicity occurs in those protected areas, although almost 47% of the endemics occupy localities outside of them, meaning that conservation efforts cannot be restricted to protected area management.

Many challenges remain to address questions arising from this examination of epiphytism. These include filling in the geographical gaps of the epiphytic flora outside of protected sites, and in regions threatened by land-use and landscape changes. Another challenge involves understanding the biology of ferns and lycophytes, especially with the goal of including the gametophytic and sporophytic stages of the life cycle of these plants, since most studies document sporophytes. And, as suggested by Luz et al. (2023) several neglected topics from biological interactions, physiology, genetics, to reproductive biology among others may foment additional foci of interest for future research.

## Supporting information

https://revistasinvestigacion.unmsm.edu.pe/index.php/rpb/article/view/31912/23541

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### Agradecimientos / Acknowledgments:

We thank Margoth Acuña for her work on epiphytes in Peru, and for her inspiring research on the ecology of vascular epiphytes. Thanks to Gabriela García and Alejandro López for their scientific curiosity, and interest on epiphytism. Blanca León and Kenneth R. Young acknowledge funding by Peru's CONCYTEC through the PROCIENCIA program within the framework of the call "Interinstitutional Alliances for Doctorate Programs" according to contract PE501084299-2023-PROCIENCIA BM. Joaquina Albán thanks the Vicerrectorado de Investigación de la Universidad Nacional Mayor de San Marcos for financial support through Proyecto B23101451. We thank the 'Life on Trees' (www.lifeontrees.org) Program, a joint initiative of the Royal Belgian Institute of Natural Sciences and the Fonds de Dotation Biotope pour la Nature in partnership with the Museo Historia Natural de la Universidad Nacional Mayor de San Marcos, Peru, the Servicio Nacional de Áreas Naturales Protegidas por el Estado (SERNANP, Peru).

### Conflicto de intereses / Competing interests:

The authors declare that there are no conflicts of interest regarding the publication of this article.

### Rol de los autores / Authors Roles:

BL: Conceptualización; Escritura-Preparación del borrador original; Redacción: revisión y edición; Curación de datos.

DM: Conceptualización; Investigación; Redacción: revisión y edición.

MK: Redacción: revisión y edición; Investigación.

GR: Redacción: revisión y edición; Investigación; Recursos.

KY: Redacción: revisión y edición; Investigación; Recursos.

NA: Investigación; Redacción: revisión y edición.

FPP: Investigación; Redacción: revisión y edición.

JA: Recursos; Redacción: revisión y edición.

### Fuentes de financiamiento / Funding:

Blanca León and Kenneth R. Young were funding by Peru's CONCYTEC through the PROCIENCIA program within the framework of the call "Interinstitutional Alliances for Doctorate Programs" according to contract PE501084299-2023-PROCIENCIA BM.

Joaquina Albán were funding by Vicerrectorado de Investigación de la Universidad Nacional Mayor de San Marcos, Proyecto B23101451.

### Aspectos éticos / legales; Ethics / legals:

Authors declare that they did not violate or omit ethical or legal norms in this research.
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