Monograph of the Elaphoglossum Ciliatum Group (Dryopteridaceae)
Total Page:16
File Type:pdf, Size:1020Kb
Monograph of the Elaphoglossum ciliatum group (Dryopteridaceae) 1,2 3 4 ALEJANDRA VASCO ,ROBBIN C. MORAN , AND GERMINAL ROUHAN 1 Author for correspondence: The New York Botanical Garden, Bronx, NY 10458–5126 USA; e-mail: [email protected] 2 The City University of New York, New York, NY 10016 USA 3 The New York Botanical Garden, Bronx, NY 10458–5126 USA; e-mail: [email protected] 4 Muséum National d’Histoire Naturelle, UMR 5202, Herbier National, 16 rue Buffon CP39, 75231 Paris Cedex 05, France; e-mail: [email protected] Abstract. The Elaphoglossum ciliatum group was supported by a previous study as monophyletic on the basis of cpDNA sequence data. The present paper provides a monograph of this group. It includes keys, full synonymy, descriptions, specimens examined, index to collectors’ names and numbers, photographs, and distribution maps for all species. Morphologically, these species are characterized by abaxial la- minar scales reduced to minute dots, resinous rhizomes, and (except for E. dussii) spiny perispores. These characteristics are not unique to the E. ciliatum group because they are found in other species of Elapholgossum sect. Lepidoglossa. Nine species are here recognized in the E. ciliatum group, with no subspecies or varieties. Six species are neotropical and primarily montane, being largely absent from Amazonia. The remaining three species are endemic to the island of St. Helena in the South Atlantic Ocean. A lectoype is designated for E. calaguala. Key Words: Dryopteridaceae, Elaphoglossum,fern,floristics, pteridophytes, taxonomy. Resumen. Se presenta la monografía del grupo de Elaphoglossum ciliatum, un grupo definido como monofilético basado en análisis de secuencias de ADN del cloroplasto. La monografía incluye claves, sinonimia completa, descripciones, especimenes examinados, un índice de colectores y sus números de colección, fotografías y mapas de distribución de todas las especies del grupo. Las especies de este grupo se caracterizan por tener las escamas de la superficie abaxial de la lámina reducidas a puntos muy pequeños, rizomas resinosos y (exceptuando E. dussii) perisporas equinadas. Sin embargo estas características no son únicas al grupo de E. ciliatum, y pueden encontrarse en otras especies de Elapholgossum sect. Lepidoglossa. Se reconocen nueve especies en el grupo de E. ciliatum, sin subespecies ni variedades. Seis especies son neotropicales y principalmente de regiones de montaña. El resto de las especies son endémicas de la isla de St. Helena en el sur del océano Atlántico. Se designa un lectotipo para E. calaguala. Elaphoglossum Schott ex J. Sm. is one of the 1899), which included 142 species—all those largest fern genera, with at least 600 species known at the time. In 1980, however, a worldwide, about three-quarters of which are comprehensive infrageneric classification was neotropical (Mickel, 1995a). Elaphoglossum is proposed by Mickel and Atehortúa based known among fern taxonomists as being taxo- mainly on sporophyte and spore morphology. nomically difficult at the species level, mainly Over the past 25 years there have been many because for such a large genus its species are regional or country-wide floristic studies, such remarkably similar. The only monographic as for Mexico (Mickel & Smith, 2004), Meso- treatment of the genus is that by Christ (Christ, america (Mickel, 1995b), Venezuela (Mickel, Brittonia, 61(3), 2009, pp. 241–272 ISSUED: 1 September 2009 © 2009, by The New York Botanical Garden Press, Bronx, NY 10458-5126 U.S.A. 242 BRITTONIA [VOL 61 1995a), Peru (Mickel, 1991), and the Mascarene to Madagascar: E. humbertii C. Chr. and Islands (Lorence & Rouhan, 2004). Yet mono- E. scolopendriforme Tardieu. In the phyloge- graphic treatments either of the entire genus or netic analyses these two species are recovered of any small groups within it have not been in a different clade not even sister to the published, mainly because of the difficulties in E. ciliatum group (Vasco et al., in press). This finding small monophyletic groups. suggests that these three characters have Molecular data were expected to be helpful in evolved at least twice in sect. Lepidoglossa. establishing relationships among the species of The E. ciliatum group is characterized by Elaphoglossum and in pointing out small mono- reddish to yellowish-brown dots on the surface phyletic groups suitable for monographic re- ofthelamina(Fig.7F). These dots result from search. Recently, two molecular phylogenetic the body of the scale being highly reduced or studies examining the relationships of the completely lost so that only the base remains Elaphoglossum species have been published embedded in the epidermis. Because of this (Rouhan et al., 2004;Skogetal.,2004). These reduction, the laminae appear glabrous, but close studies resolved some of the long-standing inspection with the naked eye can reveal questions in the systematics of Elaphoglossum. the stumps of the scales dotting the surface of They demonstrated the monophyly of the genus the lamina. In the cases in which the body of the and recognized several monophyletic sub- scales is not completely reduced, some scales groups. These subgroups largely agree with the (typically less than 0.1 mm wide) can be sections proposed on the basis of morphology by distinguished. The scales exude resin from their Mickel and Atehortúa (1980). One of the base, and they appear as shiny dots on the lamina subgroups recognized on the basis of morphol- surface. The resin is also present on the rhizomes ogy and supported by the molecular work was and when dry it appears as a dark reddish brown section Lepidoglossa H. Christ. Members of this exudate. This often stains the newspapers in section typically have phyllopodia, conspicu- which the plants are pressed in the field. ously scaly laminae, and scales (of both rhizome The spores of all species (except for E. dussii) and laminae) bearing acicular marginal cells. in the E. ciliatum group have spiny perispores The present paper concerns a clade within (Figs. 1, 2). Moran et al. (2007) found that the sect. Lepidoglossa:theElaphoglossum ciliatum presence of spines appears to be a synap- group. This group of nine species was recov- omorphy for smaller clades within the sect. ered as monophyletic by molecular phyloge- Lepidoglossa (the E. ciliatum group being one netic analyses using three chloroplast intergenic of them), whereas the plesiomorphic character spacers– atpB-rbcL, rps4-trnS, and trnL-trnF for the section was perispores without spines. (Vasco et al., in press). Morphologically the Mickel and Atehortúa (1980) classified species of this group are atypical within sect. eight of the nine species of this group in three Lepidoglossa because their laminae are incon- subsections of Elaphoglossum within sections spicuously scaly, the scales being reduced to Elaphoglossum and Lepidoglossa; E. ciliatum minute dots (typical members of the section and E. huacsaro were placed in subsect. have conspicuously and densely scaly lami- Huacsaro Mickel & Atehortúa, the three species nae). Besides that, these species have rhizomes endemic to St. Helena (E. bifurcatum, E. that dry blackish and produce a shiny, lacquer- dimorphum and E. nervosum) were placed in like exudate when dry. Their spores are also subsect. Pilosa H. Christ, and the remaining similar by being spiny (Moran et al., 2007). three species, all neotropical (E. burchellii, E. These similarities have resulted in the species gramineum and E. nigrescens), in subsect. being frequently confused in herbaria and often Tenuifolia Mickel & Atehortúa. Elaphoglos- keyed close together and compared in floras sum dussii was not assigned to any section. (e.g., Mickel, 1991, 1995b). Three species of the E. ciliatum group Although the three morphological charac- are endemic to the island of St. Helena in ters mentioned above are common to all the southern Atlantic Ocean; however, the species of the E. ciliatum group, they are E. ciliatum group is primarily neotropical, not unique to the group, being found in two distributed from Mexico and the West Indies other species of sect. Lepidoglossa endemic to southern Brazil (Fig. 3). It is largely absent 2009] VASCO ET AL: ELAPHOGLOSSUM CILIATUM GROUP 243 FIG.1. Spores of the Elaphoglossum ciliatum group. A. E. nigrescens (Ingram & Ferrell-Ingram 1825, NY). B. E. huacsaro (Ruiz-Teran 6124, NY). C. E. gramineum (Valeur 634,NY).D. E. nigrescens (Ingram & Ferrell-Ingram 1308,NY).E. E. ciliatum (Balslev & Madsen 10402,AAU).F. E. nigrescens (Maas 6858, NY). Scale bars=10 micrometers. 244 BRITTONIA [VOL 61 FIG.2. Spores of the Elaphoglossum ciliatum group. A. E. bifurcatum (Cumming s.n,NY).B. E. dimorphum (collector unknown s.n.,P).C. E. burchellii (Dusén 7225,NY).D. E. dussii (Lloyd 351, NY). Scale bars=10 micrometers. from the Amazon basin. The regions with the determined using geographical gazetteers; most species are the mountains of Costa Rica they were not on the labels of the specimens. and Panama and the northern Andes (Table I). These coordinates were used to make the dot The group primarily occurs in middle eleva- distribution maps. This study is based on tion forests, from 800 m to 2000 m. an examination of over 1000 collections In the Specimens Examined section, the (Appendix 1, 2). geographic coordinates in brackets were Key to the species of the Elaphoglossum ciliatum group 1. Lamina of the sterile leaves pinnate. 1. E. bifurcatum 1. Lamina of the sterile leaves simple. 2. Laminae of the sterile leaves irregularly lobed; St. Helena Island . .4. E. dimorphum 2. Laminae of the sterile leaves entire; St. Helena Island or elsewhere. 3. Laminae decurrent all the way to phyllopodia; scales present on the margins of the laminae, 0.3–1 mm long, dissected. 9. E. nigrescens 2009] VASCO ET AL: ELAPHOGLOSSUM CILIATUM GROUP 245 3. Laminae tapering but ending well above phyllopodia; scales present or absent on the margins of the laminae, when present 0.1–0.3 mm long, entire or nearly so.