Synoptic revision of the fern genus Elaphoglossum Schott ex J.Sm. (Dryopteridaceae) in Madagascar, with the description of 23 new taxa, all but one endemic

After 15 years of field studies in Madagascar, especially focused on the overlooked fern genus Elaphoglossum (Dryopteridaceae), a synoptic revision of the genus is here presented. Based on more than 2,600 herbarium specimens including collections over 200 years, Elaphoglossum is the second most diversified fern genus in Madagascar, with 52 species and three subspecies (with 76% of endemism). It is to be compared to the 34 species treated by Tardieu-Blot in 1960 for the “Flore de Madagascar et des Comores” or the 38 species listed by Roux in 2009 in the seminal “Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and neighboring islands”. The 55 taxa represent five out of seven existing generic sections (sect. Amygdalifolia and sect. Wrightiana being monotypic and Neotropical): sect. Lepidoglossa (29 spp. and three subspp.), sect. Elaphoglossum (17 spp.), sect. Setosa (3 spp.), sect. Squamipedia (2 spp.), and sect. Polytrichia (1 sp.). Distribution is given for each species and subspecies, and detailed for each island or archipelago in the Western Indian Ocean (La Réunion, Mauritius, Seychelles, and Comoros). Twenty species and three subspecies are newly described, all but one endemic to Madagascar: Elaphoglossum ambrense Rouhan, Elaphoglossum andohahelense Rouhan, Elaphoglossum anjanaharibense Rouhan, Elaphoglossum approximatum Rouhan, Elaphoglossum brachymischum Rouhan, Elaphoglossum cerussatum Tardieu subsp. brunneum Rouhan, Elaphoglossum coracinolepis Rouhan, Elaphoglossum desireanum Rouhan, Elaphoglossum glabricaule Rouhan, Elaphoglossum gladiifolium Rouhan, Elaphoglossum leucolepis (Baker) Krajina ex Tardieu subsp. nanolepis Rouhan, Elaphoglossum leucolepis (Baker) Krajina ex Tardieu subsp. nigricans Rouhan, Elaphoglossum longiacuminatum Rouhan, Elaphoglossum patriceanum Rouhan, Elaphoglossum perangustum Rouhan, Elaphoglossum prominentinervulum Rouhan, Elaphoglossum rakotondrainibeae Rouhan, Elaphoglossum repandum Rouhan, Elaphoglossum sabineanum Rouhan, Elaphoglossum sinensiumbrarum Rouhan, Elaphoglossum subglabricaule Rouhan, Elaphoglossum tsaratananense Rouhan, and Elaphoglossum viridicaule Rouhan. Morphological description, distribution map, and original illustrations are provided for each new taxon. Novel identification keys to the sections and all species from Madagascar are also presented.

INTRODUCTION "Elaphoglossum is more in need of a taxonomical revision than other fern genera, all the more so as many species are imperfectly known or badly delimited in comparison with their allies". Pichi Sermolli (1968) "…Elaphoglossum is overlooked by seasoned collectors because of the monotony of their aspect for most of them and are therefore overlooked because they are just not different to the naked eye. So we can consider that a large number remains unknown". Christ (1899) Pichi-Sermolli's opinion resulted from his studies of the genus Elaphoglossum in Africa "only", and that of Christ is about the genus as a whole but over a century old. However, those two statements are still relevant today throughout most of the range of this fascinating fern genus growing primarily as epiphytes in all wet tropical forests.
Elaphoglossum is monophyletic Skog et al., 2004;Lóriga et al., 2014) and sister to Mickelia R.C. Moran, Labiak & Sundue, in the bolbitidoid clade  within the subfamily Elaphoglossoideae (Pic.Serm.) Crabbe of the Dryopteridaceae (Liu et al., 2016;PPGI, 2016). Although the genus is readily distinguished among the ferns, most of its species are morphologically uniform and difficult to distinguish: nearly all the species are indeed characterized by a transversely elongated ventral meristele in the rhizome, simple fronds (blades are divided in only four species ;Vasco, Mickel & Moran, 2013), free veins, dimorphic sterile and fertile fronds, and acrostichoid sori . Contrasting with most fern genera, fertile fronds of Elaphoglossum are not critical for the taxonomy of the genus, and more generally, the number of useful characters is limited. Thus, the main characters used for describing species as well as intrageneric sections are the rhizome and frond scales. Mickel & Atehortúa (1980) proposed such a subdivision of the genus based on morphology and especially scales, and the six sections they defined have been largely supported by the molecular phylogenetic studies Vasco et al., 2015;Vasco, Moran & Rouhan, 2009;Matos & Mickel, 2019), with a seventh section added by Lóriga et al. (2014). A study of spores in relation to phylogeny further supported many of the sections and subsections (Moran, Garrison Hanks & Rouhan, 2007).
Based on the currently known richness, Madagascar hosts just below 10% of the described species, but is, however, the second center of diversity for Elaphoglossum, behind the American tropics with ca. 75% of the described species. Madagascar is a continental island of the Western Indian Ocean known to host an extraordinary biodiversity, with 12,000-14,000 vascular plant species (Callmander, 2011;Lowry et al., 2018), and listed as one of the world's hotspots of biodiversity (Myers et al., 2000). Eighty-three percent to 87% of vascular plants are endemics (Goodman & Benstead, 2005;Lowry et al., 2018), and among at least 600 species of ferns and lycophytes (Rakotondrainibe, 2003), with half probably endemic. All this diversity is however still underdocumented.
In the framework of the ongoing revision of all ferns and lycophytes of Madagascar, undertaken to update the "Flore de Madagascar et des Comores" treatment by Tardieu-blot (1960), I conducted the taxonomic revision of Elaphoglossum and identified 23 new species and subspecies for science. These new taxa are here fully described, illustrated, and mapped. The new species represent such an increase of the species diversity of the genus that I provide a novel dichotomous key including all Elaphoglossum species in Madagascar. Plants were systematically sampled as modern collections, that is, including herbarium specimens, silica-dried leaf sample, and photos (Gaudeul & Rouhan, 2013). Complete sets of all collections made during these field trips are deposited at TAN or TEF, and with a few exceptions at P; duplicates, when available, have been sent elsewhere (or will be sent right away after publication) particularly to K, MO, NBG, NY (herbarium codes follow Thiers, 2018).

Herbarium-based studies
The taxonomic revision that led to defining taxa and building novel identification keys is based on the examination of over 2,600 herbarium specimens representing 2,186 gatherings housed at P, and on-field observations of most Elaphoglossum species. All specimens were databased and are freely available in the Paris Herbarium database at https://science.mnhn.fr/institution/mnhn/collection/p/item/search?lang=en_US. Additional specimens from other herbaria were examined in hand and annotated (BM, G, K, MO, NY, P, PR, TAN, TEF, US) or examined as online images (B, BR, PRE). All measurements, colors and other details included in the descriptions were based on herbarium specimens and data derived from field notes. In evaluating the variability of each species, habitat and ecology were noted in the field, but information on these features were also taken from other herbarium labels.

Illustrations and morphological characters
Herbarium specimens were examined under dissection microscope Leica MZ6, and close-up images acquired through a camera Leica DFC425 provided illustrations for each taxon; scales were mounted in glycerin gelatin between slide and slip-cover, and these permanent slides were imaged using a slide scanner Nikon CoolScan V ED. The terminology used to describe the plants is based on Lellinger (2002).

Distribution maps
Distribution maps of new taxa were based on all cited specimens and generated with QGIS 2.14 (QGIS Geographic Information System. Open Source Geospatial Foundation Project. http://qgis.osgeo.org). A background map included five altitudinal ranges corresponding globally to those generally recognized in Madagascar (Humbert, 1955;Faramalala, 1995): 0-400 m (green), 400-800 m (yellow), 800-1,200 m (light brown), 1,200-1,800 m (medium brown) and >1,800 m (dark brown). Localities of specimens were represented by red dots (and open circles represented the six main cities in Madagascar). Distribution is also described in the text for each species and subspecies according to the five Malagasy phytogeographic domains as defined by Humbert (1955): East, Sambirano, Center, West, and South.

New botanical taxa
New botanical taxa were described only after considering all species known at least in Madagascar, Africa, Western Indian Ocean Islands (Comoros, Seychelles, La Réunion, Mauritius), and circumaustral islands from the Atlantic and the Indian Ocean. Thus, a morphological comparison to most closely-related species from those areas is provided through diagnoses and keys.
The electronic version of this article in Portable Document Format (PDF) will represent a published work according to the International Code of Nomenclature for algae, fungi, and plants ( ICN), and hence the new names contained in the electronic version are effectively published under that Code from the electronic edition alone. In addition, new names contained in this work which have been issued with identifiers by IPNI will eventually be made available to the Global Names Index. The IPNI LSIDs can be resolved and the associated information viewed through any standard web browser by appending the LSID contained in this publication to the prefix "http://ipni.org/". The online version of this work is archived and available from the following digital repositories: PeerJ, PubMed Central, and CLOCKSS.

RESULTS AND DISCUSSION
With 52 species and three subspecies, Elaphoglossum ranks as the second most diverse fern genus in Madagascar (after Asplenium L.) (Table 1). This species diversity is to be compared to the 34 species treated by Tardieu-Blot in the Flora of Madagascar (1960) or the 38 species more recently listed by Roux (2009). The 55 taxa take account of the identification of 20 new species for science, and three new subspecies, all but one endemic to Madagascar. New taxa were first discovered not only by intensive and focused prospections in the field, but also by in-depth studies of a plethora of unidentified and misidentified earlier specimens kept in Herbaria: in particular, the Paris herbarium (P) houses one of the most important collections of Malagasy plants (Le Bras et al., 2017), and likely the most diversified and abundant collection of the Malagasy ferns (more than 38,800 specimens), thanks to general collectors who devoted their lives to the flora of Madagascar (e.g., Henri Perrier de la Bâthie and Henri Humbert), to pteridologists who gathered critical and abundant collections made by others (Roland Bonaparte), and to more recent pteridologists like France Rakotondrainibe or myself.
The endemism in the genus is high in Madagascar (76% representing 39 species and three subspecies), with five sections represented. The two remaining sections, sect. Amygdalifolia and sect. Wrightiana, are monotypic and endemic to the Neotropics (Mickel & Atehortúa, 1980;Lóriga et al., 2014). This species diversity in Madagascar was best explained by more than 10 independent long distance dispersal events from the Neotropics to Madagascar giving rise to many distinct lineages followed by insular speciations .
With 29 species, sect. Lepidoglossa is the most diversified in Madagascar, followed by sect. Elaphoglossum (17 spp.), reflecting their likely most important diversities also at the world level (Table 2).
Section Polytrichia and Setosa, together forming the subulate scales clade, are poorly represented by a few non-endemic species: Elaphoglossum hybridum (Bory) Brack. is even unique in the genus in being widespread from South America to Africa, Madagascar and nearby islands (Matos & Mickel, 2014).
By contrast, only two species in section Squamipedia are endemic to Madagascar, and all other 16 species of the section are endemic to the Neotropics (Vasco, Mickel & Moran, 2013;Vasco et al., 2015). The two Malagasy species, E. nidusoides Rouhan & Rakotondr. and E. marojejyense Tardieu, are sister group to the Neotropical species and are  Since no morphological character allow distinguishing one section from the other in Madagascar (see Rouhan, Rakotondrainibe & Moran, 2007;Matos, Vasco & Moran, 2018), the two sections are included in a single key.
38a. Fronds narrowly elliptic or oblanceolate (rarely linear); sterile petioles <½ of total frond length; laminar scales ciliate (10-15 (20)  Diagnosis:-Elaphoglossum ambrense differs from the much more widespread E. lancifolium (Desv.) C.V.Morton by the absence of stellate scales on the fronds, and by entire, more flexible, and non-ferrugineous rhizome scales. The rhizome scales of E. ambrense and E. anjanaharibense Rouhan are similar, but E. ambrense differs in the absence of stellate scales on the fronds, broader (>1 cm) and non-angustate laminae, fertile fronds longer than the sterile ones, the epiphytic habitat, and plants not forming large populations. The rhizome scales are also somewhat similar to those of E. andohahelense Rouhan but they are more or less patent (vs. appressed) on thicker rhizomes, and the laminar scales are shorter to ovate, and distributions of the two species do not overlap.
Etymology:-The specific epithet derives from the 'Montagne d'Ambre' National Park, a mountain area rich in ferns, and the single locality known for the species.  (Humbert, 1955;Faramalala, 1995)  Habitat and distribution:-Endemic to Madagascar, Elaphoglossum ambrense is rare and grows as epiphytic in wet evergreen forests of Montagne d'Ambre (North), in the Central phytogeographic domain, 1,300-1,475 m (Fig. 2).
Etymology:-The specific epithet derives from the Malagasy name "Andohahela", a mountain area rich in ferns, a national park, and the single locality known for the species; Andohahela is derived from "Andohan'ny-", at the begnning of, and "-Tehela", the name of a tribe from the village of Eminiminy located in the area of the Park (Pierrot Rabenandrasana & Lalao Andriamahefarivo, pers. com., 2020).
Habitat and distribution:-Endemic to Madagascar, E. andohahelense is known only from the type gathering and grows as epiphytic in wet evergreen forests from Andohahela area    E. aspidiolepis from Madagascar), and the fertile fronds are shorter than the sterile ones (vs. fertile fronds longer in E. welwitschii and E. aspidiolepis). The rhizome scales are similar to those of E. ambrense Rouhan, but E. anjanaharibense differs by showing stellate, suborbicular scales on the fronds (vs. irregularly shaped, ovate to lanceolate, margins subentire to erose), narrower fronds <1 cm broad with angustate apices, fertile fronds shorter than the sterile ones, and it grows as epilithic in large populations on rocks in bed or on river banks. Description:-Rhizomes long-creeping, 2-4 mm diam., glutinous, densely scaly (Fig. 5B); rhizome scales more or less patent, narrowly lanceolate to linear, 2.5-3.5 × 0.3-0.5 mm, dark castaneous, bright, translucent, papyraceous to rigid, bases truncate to cordate, apices attenuate, margins entire (Fig. 5C).
Fertile fronds shorter than the sterile ones, laminae linear and with longer petioles (¼-⅓ of total frond length).
Etymology:-The specific epithet derives from the Malagasy name "Anjanaharibe-Sud" Special Reserve, a mountain area rich in ferns, and the single locality known for the species; Anjanaharibe is derived from "Zanahary", God, and "be", great, and the whole word means: where the great God is (Lalao Andriamahefarivo, pers. com., 2020).
Habitat and distribution:-Endemic to Madagascar, E. anjanaharibense is rare and grows as epilitic on river bank, in wet evergreen forests from Anjanaharibe-Sud (northern Madagascar) in the Central phytogeographic domain, 1,120-1,300 m (Fig. 6).
Additional specimens examined (paratypes):-MADAGASCAR. Rakotondrainibe 5020 (P). Diagnosis:-Elaphoglossum approximatum belongs to a group of four species (with E. rakotondrainibeae Rouhan, and E. longiacuminatum Rouhan, E. viridicaule Rouhan), having rhizomes with green apices in natura, and rhizome scales homogeneous, patent, to 5.5 mm long, dark castaneous with black hues, with entire margins, papyraceous and soft in texture. Elaphoglossum approximatum however differs from E. rakotondrainibeae and E. longiacuminatum by more closely spaced fronds, borne on shorter rhizomes. Unlike E. longiacuminatum, the laminae of E. approximatum are not long-acuminate at base, nor obtuse to round at apices; rhizomes are thicker than those of E. rakotondrainibeae; and the rhizome scales are long and soft, unlike those of E. viridicaule that are short, sclerotic and brittle.
Fertile fronds about as long as the sterile ones, petioles as long or longer (3/10-½ of total frond length), and laminae narrower (<2 cm broad); sporangia not reaching margins, leaving all around a narrow, marginal strip.
Etymology:-The specific epithet derives from the Latin verb approximo, with its past participle approximatus meaning approximate. It is for the closely spaced fronds of the rhizomes, especially compared to E. rakotondrainibeae Rouhan, a species otherwise morphologically similar to E. approximatum.
Habitat and distribution:-Endemic to Madagascar, E. approximatum is rare and grows as epiphytic (rarely terrestrial) in wet evergreen forests from Northern Madagascar, in the Central phytogeographic domain, 780-1,546 m (Fig. 8). Diagnosis:-Elaphoglossum brachymischum is similar to E. pseudovillosum Bonap. although the two species are known from two areas far apart from each other, and with distinct habitats: E. brachymischum was collected in a wet evergreen forest at 800 m asl in the very South of Madagascar, and E. pseudovillosum in a mountain sclerophyll forest at 1,500 m asl in the North.
Etymology:-The specific epithet combines the Greek prefix brachy-, short, with the name mischos, petiole; it refers to the short-petiolate fronds of the species.
Habitat and distribution:-Endemic to Madagascar, E. brachymischum is known only from the type gathering and grows as epiphytic in wet evergreen forest from the very South of Madagascar, in the Central phytogeographic domain, 800 m (Fig. 10). Diagnosis:-Elaphoglossum cerussatum subsp. brunneum differs from the type subspecies by the rhizome scales which are not white or light orange brown, but castaneous, matte (sometimes slightly bright), usually broader ((0.5)0.7-1.5 mm) (Fig. 11C), and arranged in layers such that scales are hardly discernable and separable from each other (Fig. 11B). Additionnaly, frond scales in E. cerussatum subsp. brunneum are light orange brown (vs. white in the type subspecies) and laminar scales are more regularly stellate (Figs. 11D and 11F). Elaphoglossum cerussatum subsp. brunneum is morphologically close to the African species E. welwitschii (Baker) C.Chr., considering the stellate scales on laminae and the rhizome scales castaneous; it differs however from the latter by broader laminae >2 cm, with an intramarginal vein (Fig. 11G), and laminar apices often round (rarely obtuse to acute) (Fig. 11A).
Etymology:-The subspecific epithet derives from the Latin adjective brunneus, brown; it refers to the color of rhizome scales that are darker than those of the type subspecies.
Fertile fronds slightly shorter than, or as long as the sterile ones, long-petiolate (⅖-½ of total frond length); laminae linear, narrower than those of sterile ones, 1.1-1.7 cm broad.
Etymology:-The specific epithet derives from the Greek adjective coracinus, black raven, and name lepis, scale; it refers to the singular laminar scales that are black.
Habitat and distribution:-Endemic to Madagascar, E. coracinolepis is rare and grows as epiphytic in wet evergreen forests from the North and Center-North, in the Central phytogeographic domain, 850-1,450 m (Fig. 14). Diagnosis:-Elaphoglossum desireanum can be easily confused with E. scolopendriforme Tardieu but it differs from the latter species by lateral veins more closely spaced, by a lower angle at which these lateral veins form an angle with the median vein, by an intramarginal vein discontinuous or absent, by thicker laminae, by rhizome scales larger, and by fronds usually longer-petiolate. Elaphoglossum desireanum more clearly differs from E. achroalepis (Baker) C.Chr by the absence of a continuous intramarginal vein, and by the rhizome scales that are light brown, ovate to lanceolate, subentire, broader and (vs. whitish to light red, narrowly lanceolate, 0,3-1,0 mm broad, margins with numerous, pluricellular, long appendages).
Fertile fronds slightly shorter than the sterile ones, longer-petiolate (⅓-½ of total frond length); fertile laminae linear, <1 cm broad; sporangia not reaching margins, leaving all around a narrow, marginal strip.
Eponymy:-The specific epithet honors our friend Désiré Ravelonarivo, Malagasy botanist working for MBG-Madagascar; he is native of the Andapa area where the species is well represented.
Habitat and distribution:-Endemic to Madagascar, E. desireanum is rare and grows as epiphytic in wet evergreen forests from the North, in the Eastern and Central phytogeographic domains, 620-1,600 m (Fig. 16). Diagnosis:-Elaphoglossum glabricaule is similar to E. humbertii C.Chr. and E. perrierianum C.Chr. in having thin, glabrous and glutinous rhizomes. But it differs from the two latter species by closer spaced fronds that are also shorther, narrower and subglabrous (vs. densely scaly in E. perrierianum, and with glutinous dots in E. humbertii); E. glabricaule differs also from E. humbertii by green rhizomes in natura (vs. black in E. humbertii).
Sterile fronds erect, inserted in two distinct rows, 3-5 mm apart, up to 21 cm long, subsessile (petioles not distinct) (Fig. 17A); phyllopodia conspicuous, black and glutinous, 1-4 mm long; sterile laminae chartaceous, narrowly linear, 1.0-2.3 mm broad, bases long-attenuate and decurrent in a narrow wing to the phyllopodia, apices angustate, glabrous on both surfaces except some minute, irregular squamules similar to those on rhizomes (Fig. 17C); median veins prominulous on both surfaces, round on the abaxial surface, round to flat on the adaxial surface; lateral veins barely or not visible, simple, free, apices enlarged without hydathodes or anastomoses.
Etymology:-The specific epithet derives from the Latin adjective glaber, glabrous, and name caulis, stem; it refers to the glabrous rhizomes. Habitat and distribution:-Endemic to Madagascar, E. glabricaule is known only from the type gathering (Ankerana), and grows as epiphytic in wet evergreen forest from the Center, in the Central phytogeographic domain, 1,072-1,179 m (Fig. 18).
Sterile fronds erect to spreading, inserted in two or three distinct rows, <7 mm apart (10-)20-60 cm long (Fig. 19A); petioles short and inconspicuous (fronds subsessile) to 15 cm long with laminae long-decurrent into a narrow wing often to the base, 1-2 mm diam., with numerous glutinous dots, ferrugineous and translucent turning sometimes black and opaque; some scales at the base only, similar to those of rhizomes; sterile laminae herbaceous, linear to narrowly elliptic, 10-50 × (0.5-)1.0-2.0 cm, bases long-acuminate to attenuate, apices attenuate, margins undulate, both surfaces without scales, with numerous glutinous dots at first ferrugineous, bright and translucent, turning sometimes whitish or blackish, matte and opaque (Figs. 19E and 19F); median veins prominulous on both surfaces, round on the abaxial surface (Fig. 19F), little or not sulcate (with angular ribs) on the adaxial surface (Fig. 19E); lateral veins visible, slightly prominulous on both surfaces, simple or bifurcate, free, apices submarginal enlarged without hydathodes or intramarginal vein.
Etymology:-The specific epithet derives from the Latin name gladius, sword, and folium, leaf; it refers to the frond shape.
Note:-Size, texture, and colors of the rhizome scales are variable among individuals (e.g., specimens of the gathering Rakotondrainibe 5887).
Habitat and distribution:-Endemic to Madagascar, E. gladiifolium is rare to frequent, and grows as epiphytic or epilithic in wet evergreen forests from North to South, in the Eastern and Central phytogeographic domains, 550-2,063 m (Fig. 20).    (Humbert, 1955;Faramalala, 1995) are represented in green ( Etymology:-The subspecific epithet derives from the Greek adjective nânos, small or smaller, and the name lepis, scale; it refers to the smaller size of the laminar scales compared to those of the type subspecies. Habitat and distribution:-Endemic to Madagascar, Elaphoglossum leucolepis subsp. nanolepis is rare and grows as epiphytic in wet evergreen forests from the North, in the Central phytogeographic domain, 1,100-1,475 m (Fig. 22); this distribution area does not overlap with that of the other two subspecies, subsp. leucolepis and subsp. nigricans.
Additional specimens examined (  Diagnosis:-Elaphoglossum leucolepis, subsp. nigricans differs from the type subspecies by the petiole scales that are mostly concolorous, black to dark brown (only the marginal cilia are sometimes white) (Fig. 23E), by the presence of these scales also in the basal half (at least) of the abaxial median veins (Figs. 23A and 23G), and by often longer fronds, 34-80 cm (vs. 20-60 cm), with obtuse to acute apices.
Etymology:-The subspecific epithet derives from the Latin adjective nigricans, blackish, refering to the color of the petiole scales.
Habitat and distribution:-Endemic to Madagascar, Elaphoglossum leucolepis subsp. nigricans is rare and grows as pendent epiphytes in wet evergreen forests from Center-South and South (Ranomafana, Andringitra, Andohahela) in the Central phytogeographic domain, 800-1,400 m (Fig. 24). This distribution area does not overlap with that of the other two subspecies, leucolepis and nanolepis. Subspecies nigricans might have a preference for riverside habitats, as, at least 4 out of the 6 known gatherings were in this habitat. Diagnosis:-Elaphoglossum longiacuminatum shows rhizome scales similar to those of E. approximatum Rouhan and E. rakotondrainibeae Rouhan (it is sympatric with the latter: see Rouhan et al., 1555 andRouhan et al., 1557), but E. longiacuminatum differs by long-decurrent fronds, round to obtuse laminae at apices, median veins obviously ending before the laminar apices, and rhizomes thicker than those of E. rakotondrainibeae. The soft and longer rhizome scales make the distinction easier with E. viridicaule Rouhan.
Etymology:-The specific epithet derives from the Latin adjectives longus, long, and acuminatus, acuminate; it refers to the shape of the base of sterile laminae.
Habitat and distribution:-Endemic to Madagascar, E. longiacuminatum is known only from the type gathering, and grows as terrestrial in wet evergreen, summit forest, from the North, in the Central phytogeographic domain, at 1,300 m (Fig. 26). Diagnosis:-Elaphoglossum patriceanum differs from E. coriaceum by the presence of laminar scales, numerous glutinous dots on fronds, by median veins sulcate but not immersed, laminae overall flat and not revolute, tip of laminar apices obtuse (vs. attenuate to angustate), and fertile fronds usually longer than the sterile ones (vs. shorter or equaling). Also similar to E. subglabricaule Rouhan, E. humbertii C.Chr. and E. gladiifolium Rouhan, E. patriceanum is distinguished by the presence of laminar scales, and rhizomes all over densely scaly. The substellate scales and glutinous dots on fronds might be compared to those of E. lancifolium (Desv.) C.V.Morton, but E. patriceanum shows smaller and darker rhizome scales, and coriaceous laminae with obtuse apices.
Sterile fronds erect, inserted in two distinct rows, <5 mm apart, 5-20(-27) cm long (Fig. 27A); petioles short and inconspicuous (subsessile fronds) to 10 cm long with long-decurrent laminae, 0.9-1.5 mm diam., with scales and numerous glutinous dots ferrugineous to black (Fig. 27D); petiole scales scattered, of two kinds but all non-subulate: the first ones similar to those of rhizomes but shorter, ovate to short-oblong, 0.3-0.6 × 0.2-0.3 mm, margins subentire, and the second ones similar to those of laminae (see below); sterile laminae coriaceous and rigid, linear or narrowly oblanceolate, 5-17 × 0.5-1.0 cm, bases attenuate and decurrent, apices cuneate but obtuse to round at the very tip, both surfaces deciduously scaly (scales persisting longer on margins) and with numerous glutinous dots ferrugineous, at first bright and translucent turning sometimes   (Humbert, 1955;Faramalala, 1995)  Fertile fronds as long as or slightly longer than the steriles ones, longer-petiolate (½-⅗ of total frond length); fertile laminae narrowly oblong, narrower than or as broad as the sterile ones, bases acute.
Eponymy:-The specific epithet honors our friend Patrice Antilahimena, Malagasy botanist working for MBG-Madagascar, collector of a paratype in the Ambatovy area where he has been much contributing to the knowledge of the flora.
Note:-Elaphoglossum patriceanum is sympatric -and thus has been confused-with E. humbertii C.Chr. and E. gladiifolium Rouhan, as illustrated by for example, Humbert 22448bis representing E. humbertii, and Humbert 22448 being a mixed gathering with specimens representing E. patriceanum and others E. gladiifolium.
Habitat and distribution:-Endemic to Madagascar, E. patriceanum is rare to locally frequent and grows as epiphytic in wet evergreen forests from the Nord and Center, in the Eastern and Central phytogeographic domains, 400-1,700 m (Fig. 28). Diagnosis:-Elaphoglossum perangustum resembles E. rakotondrainibeae Rouhan, E. longiacuminatum Rouhan, and E. approximatum Rouhan especially by the dark rhizome scales, but it differs by long-creeping rhizomes with rhizome scales scattered and dark brown to black, by widely spaced fronds, and narrow, linear laminae. Elaphoglossum perangustum differs from E. coursii Tardieu by longer, papyraceous and fully translucent rhizome scales, and by prominulous median veins that are not adaxially immersed.
Habitat and distribution:-Endemic to Madagascar, E. perangustum is rare and grows as terrestrial in large populations (including some dozens of fronds), in evergreen forests from the Centre, in the Central phytogeographic domain, 950-1,450 m (Fig. 30). Although being known by only four gatherings, E. perangustum might be more widely distributed because the species could have been mostly ignored in being confused with E. lepervanchei (Bory ex Fée) T.Moore which is one of the most frequent and very variable species including rather narrow fronds (rhizome scales are however distinct). ) Schelpe (Africa and Western Indian Ocean), but it is distinguished by different rhizome scales, and especially by particularly prominulous lateral veins, tangible and visible on both sides, which look like Chinese shadow. This latter character is shared with E. sinensiumbrarum Rouhan sp. nov., but E. prominentinervulum is clearly distinguished by the rhizome scales, which are ovate to lanceolate, dark castaneous and sometimes partially sclerotic (vs. narrowly lanceolate to linear, light brown to stramineous, translucent).
Fertile fronds about as long as the sterile ones, longer petiolate (>½ of total frond length), laminae narrower (<0.9-1.7 cm); sporangia not reaching margins, leaving all around a narrow, marginal strip.  (Humbert, 1955;Faramalala, 1995)  Eponymy:-The specific epithet honors our colleague, Dr. France Rakotondrainibe, who much contributed to the knowledge of pteridophytes in Madagascar, and especially in the Marojejy national Park (Rakotondrainibe, 2000;Rakotondrainibe et al., 2003) where she collected the type gathering.
Habitat and distribution:-Endemic to Madagascar, E. rakotondrainibeae is rare and grows as epiphytic in evergreen forests from the North, in the Central phytogeographic domain, 1,200-1,700 m (Fig. 34).
Etymology:-The specific epithet derives from the Latin adjective repandus, irregularly wavy, and refers to the laminar margins.
Note:-Elaphoglossum repandum is easily recognized among other Malagasy species of the genus, by small, linear, red, and patent (not subulate) frond scales, and by fronds small, narrowly oblanceolate to oblong, with repand margins.
Habitat and distribution:-Endemic to Madagascar, E. repandum is known only from the type gathering and grows as epilithic in wet evergreen forests from Andohahela area in the very South of Madagascar, in the Central phytogeographic domain, 500 m (Fig. 36).
Eponymy:-Elaphoglossum sabineanum is named in memory of our good friend and colleague Sabine Comtet-Andriamanjatoarivo (1961, a Malagasy botanist who was technician of the Herbarium P in the Muséum national d'Histoire naturelle (Paris, France); her botanical skills and human qualities were great, rare, and appreciated by everyone.
Etymology:-The specific epithet derives from the Latin adjective, sinensis, Chinese, and name umbrae, shadows; it refers to the lateral veins wich are particularly prominulous and look like Chinese shadows in the wild.  (Humbert, 1955;Faramalala, 1995)  Habitat and distribution:-Endemic to Madagascar, Elaphoglossum sinensiumbrarum is rare and grows as terrestrial or epiphytic in wet evergreen forests in Center, in the Central phytogeographic domain, 940-1,200 m (Fig. 40). Although being known by only 3 localities far from each other, E. sinensiumbrarum might be more widely distributed because the species could have been mostly ignored in being confused with E. lepervanchei (Bory ex Fée) T.Moore which is one of the most frequent and very variable species. Diagnosis:-Elaphoglossum subglabricaule, differs from other species with glutinous dots on fronds by short-creeping rhizomes with a few rhizome scales, and closely-spaced fronds (vs. E. humbertii C.Chr.), by fronds without scales (vs. E. patriceanum Rouhan and E. lancifolium (Desv.) C.V.Morton), by herbaceous laminae (vs. coriaceous in E. patriceanum) which are oblanceolate with obtuse to round apices, and smaller and rare to scattered rhizome scales (vs. dense rhizome scales in E. gladiifolium Rouhan and E. patriceanum). Elaphoglossum subglabricaule is clearly distinct from E. glabricaule Rouhan and E. perrierianum C.Chr. (all three species have glabrous or subglabrous rhizomes) by the narrowly oblanceolate laminae (vs. narrowly linear, and linear in E. glabricaule and E. perrierianum, respectively), and by fronds without scales (vs. E. perrierianum).