Cahiers scientifiques de l'océan Indien occidental 5, 2014: 21-26. 21 Confirmation of the presence of the fern species: Lepisorus schraderi (Mett.) Ching in Reunion island (Polypodiales: Polypodiaceae) YANNIS ROBERT1,2, JEAN MAURICE TAMON1 & HERMANN THOMAS1 1 - Association des naturalistes de Bourbon, 18 Rue des Capucines, 97431 La Plaine des Palmistes, île de la Réunion. yrobert@ecologie.re 2 - Association réunionnaise d'écologie, 188 chemin nid joli, 97430 Le Tampon, île de la Réunion reçu le 08/09/2014, accepté le 24/12/2014 ABSTRACT: Reunion Island (Mascarene Archipelago, Indian Ocean) belongs to one of the thirty-four world biodiversity hotspots. On this island, where approximately 250 species of Pteridophytes were recorded, the presence of Lepisorus schraderi (Mett.) Ching is confirmed for the first time. Only, one population of this fern was located in a mountain forest near the Piton de la Fournaise volcano. As L. schraderi could be confused with L. excavatus (Bory ex Willd.) Ching also present on the island, this paper provides a key to identify correctly L. schraderi and L. excavatus, using morphological characters, as well as cytologic methods. RÉSUMÉ: La présence de Lepisorus schraderi (Mett.) Ching (Polypodiaceae) est confirmée pour la première fois sur l'île de La Réunion. Les caractères morphologiques et cytologiques permettant de distinguer les deux espèces réunionnaises de Lepisorus, L. schraderi et L. excavatus (Bory ex Willd.) Ching, sont précisés. KEYWORDS: Lepisorus schraderi, Pteridophytes, Reunion island, Mascarene, chromosome numbers MOTS CLÉS: Lepisorus schraderi, Ptéridophytes, La Réunion, Mascareignes, nombres chromosomiques INTRODUCTION The studies on Pteridophytes species from Reunion island reveal regularly some new details. For example, recently, ROBERT (2011) showed that Christella parasitica (L.) Lév. ex Holttum is a new native fern. DUBUISSON et al. (2014) also described a new endemic variety: Crepidomanes inopinatum (Pic. Serm.) J.P. Roux var tamonii Y. Robert & Dubuisson. Lepisorus (J. Sm.) Ching is a fern genus including approximately 40 species (HENNIPAN & al., 1990; ZINK, 1993), mainly distributed in the Sino-Himalayan region. Around six Lepisorus species were observed in the Afro-Malagasy region including the Mascarene islands. A single one is present in the Hawaiian archipelago. WANG et al. (2012) showed that the Afro-Malagasy species result from a rapid radiation which began around 1.5 My ago from an ancestor native to the SouthWest of China. There are three species in the Malagasy region (TARDIEU-BLOT, 1960; ROUX, 2009): Lepisorus excavatus (Bory ex Willd.) Ching, Lepisosrus schraderi (Mett.) Ching and Lepisorus perrierianus (C. Chr.) Ching. L. excavatus and L. schraderi are present in Madagascar, in tropical and southern Africa while L. perrierianus is endemic to Madagascar. Hitherto, a single species, L. excavatus was known on Reunion island (CORDEMOY, 1891; TARDIEU-BLOT, 1960; BADRÉ, 2008; ROUX, 2009). 22 Lepisorus schraderi (Mett.) Ching in Réunion island Y. ROBERT, J.-M. TAMON & H. THOMAS It should be noted, however, that preliminary works conducted by the botanist Th. Cadet mentioned the presence in Reunion island of a plant identified by F. Rakotondrainibe as L. schraderi (Grangaud, comm. pers.). A voucher specimen (Cadet 3189) classified in Cadet’s Herbarium is preserved at the Reunion University Herbarium (REU). Th. Cadet collected this species in Acacia heterophylla (Lam.) Willd. forest over the « Rivière de l'Est » bottom near the Piton de la Fournaise volcano. This work provides the confirmation of the presence of L. schraderi on Reunion island. The comparison between L. schraderi and L. excavatus (Tab. I), the local and worldwide distribution as well as the cytology of L. schraderi and the threats against this fern into its environment are described in this paper. MATERIALS AND METHODS A specimen of L. schraderi was collected in Acacia heterophylla forest over the « Rivière de l'Est » bottom near the Piton de la Fournaise volcano as it was done by Th. Cadet. A specimen of L. excavatus was collected in Jean Maurice Tamon’s garden, located at the Plaine des Palmistes . The collected samples allowed to determine the chromosome number of both L. schraderi and L. excavatus by using GIBBY method (1985) which has been adapted by ROBERT (2014). MATERIAL EXAMINED: REUNION ISLAND: Commune de Sainte Rose, rempart de la rivière de l'Est near the Piton de la Fournaise volcano, alt. 1 900 m, 26/03/1971, Cadet 3189 (REU). NOMENCLATURAL ASPECT: – Lepisorus schraderi (Mett.) Ching in Bulletin of the Fan Memorial Institute of Biology 4, 3: 51. 1933b. – Polypodium schraderi Mett. in Abhandlungen herausgegeben von der Senckenbergischen Naturforschenden Gesellschaft 2, 1: 98, pl. 2, fig. 11. 1856b. Type: "Prom. b. spei", C. H. F. Hesse s. n. (LE. holo.). – Niphobolus schraderi (Mett.) Keyserl., Polypodiaceae et Cyatheaceae herbarii bungeani: 39. 1873. – Polypodium lineare Thunb. var schraderi (Mett.) Sim, Handbook of the ferns of Kaffraria: 52, pl. LVI. 1891, nom. nov. for Polypodium elongatum Schrad. (1818: 915). – Pleopeltis schraderi (Mett.) Tardieu in Flore de Madagascar et des Comores, 5 ème FamillePolypodiacées (sensu lato) [5(11) Blechnacées-5(14) Polypodiacées (sensu stricto)]: 110. 1960a. – Polypodium elongatum Schrad. in Göttingische Gelehrte Anzeigen (1818: 915), non Aiton (1789: 465), nom. superfl. [McNeill et al. (2006) Art. 53. 1]. Type: South Africa, Grahamstown, C. H. F. Hesse s. n. (LE. holo.). – Phymatodes elongata (Schrad.) Pappe & Rawson, Synopsis filicum Africae australis: 41. 1858, nom illeg. [MacNeill et al. (2006) Art. 53.1], non (Kaulf.) C. Presl. (1836: 196). – Polypodium gueinzii Mett. in Abhandlungen herausgegeben von der Senckenbergischen Naturforschenden Gesellschaft 2, 1: 91, pl. 3, figs 18, 19. 1856b, as "gueintzii". Type: "Ad portum Natalensem lectum", W. Gueinzius s. n. (LZ, Holo. B, S, ? iso.). – Polypodium lineare Thunb. var gueinzii (Mett.) C. Chr., Index filicum: (540: 1906). - L. gueinzii (Mett.) Ching in Bulletin of the Fan Memorial Institute of Biology 4, 3: 51 1933b, as "gueintzii". Cahiers scientifiques de l'océan Indien occidental 5, 2014: 21-26. 23 LIST OF EXSICCATA FROM REUNION ISLAND (IN YANNIS ROBERT PRIVATE HERBARIUM): Lepisorus schraderi: Sainte Rose, rempart de la Rivière de l'Est near the Piton de la Fournaise volcano, 13/05/2014, Robert 1701. Lepisorus excavatus: Plaine des Palmistes, Jardin de Jean Maurice Tamon, 11/07/2014, Robert 1779. RESULTS L. schraderi was found in the « Rivière de l'Est » bottom near the Piton de la Fournaise volcano at an altitude of 1 700 to 1 900 m. It grows among the native vegetation on the rim over the excavation where the river begins. This fern is an epiphyte growing on several trees or shrubs such as Acacia heterophylla, Sophora denudata Bory, Claoxylon glandulosum Boivin ex Baill., Dombeya ficulnea Baill. It is usually found with two other Polypodiaceae: L. excavatus and Pleopeltis macrocarpa (Bory ex Willd.) Kaulf. Its presence closer to these last two species could explain why this new species was not detected earlier because of the possible confusion. Moreover, a broad similarity with a fourth species belonging to the same family: Belvisia spicata (L. f.) Copel could also noted. The confusion is more likely when, under bad water conditions, B. spicata has not its fertil ear. Indeed, L. schraderi and B. spicata can withstand water stress by keeping a strong desiccation during drought period and can be revitalized when rains return. Our countings gave for L. excavatus n = 36 (Fig. 1a) and for L. schraderi n = 72 (Fig. 1b) this last result constitutes a first record. Thus, L. excavatus would be diploid while L. schraderi would be tetraploid by taking as basic chromosome number x = 36 in accordance with WANG et al. (2011). 1a 1b Figure 1. – Lepisorus spp. : 1a) L. excavatus, YR 1779: Microphotography and drawing of meiosis showing 36 bivalents; 1b) L. schraderi YR 1701: Microphotography and drawing of meiosis showing 72 bivalents. Scale bar = 10 µm DESCRIPTION OF L. SCHRADERI (FIG. 2). Rhizome shortly creeping, 2-3 mm in diameter, bearing black scales, peltate, lanceolate to ovate, acuminate. Frond tufted, evergreen. Stipe short, glabrous or sometimes with few scattered scales (Fig. 2a). Lamina narrowly lanceolate, gradually attenuate towards the acute apex, base deccurent on the very short stipe, simple, texture thick and fleshy, both sides glabrous at maturity, margins entire. Sorus round, arranged in two rows in distal third to half of the lamina (Fig. 2b); with small peltate paraphyse when young. 24 Lepisorus schraderi (Mett.) Ching in Réunion island Y. ROBERT, J.-M. TAMON & H. THOMAS Table I. – Comparison between L. schraderi and L. excavatus Plant parts Rhizome : - Diameter - Scales - Waxy coating Lamina - Texture - Abaxial side Cytology L. schraderi L. excavatus 2 - 3 mm black none More than 5 mm brown present fleshy glabrous or with few scattered scales Tetraploid (n = 2x = 72) membranous glabrous Diploid (n = x = 36) 2a 2b Figure 2. – Lepisorus schraderi, 2a) Short stipe with scattered scales on costa; 2b) Whole plant showing sorus in the distal third part of the frond (photographed by Fred Henze). Scale bar = 1 cm DISCUSSION L. Schraderi was observed only in the hygrophilous mountain forests [Code Hab. : 49.31], located over the « Rivière de l’Est » bottom near the Piton de la Fournaise volcano at an altitude of 1 900 m, exactly in the Acacia heterophylla forest [Code Hab. : 49.314]. WANG et al. (2012) related a sample collected in Bébour forest by Ronnald Viane (RV8253) in 1999, identified as L. schraderi. However, Ronnald Viane (comm. pers.) confirmed that a part of his collection, realized in 1999, preserved in its personal herbarium, corresponds to L. excavatus. In the paper of WANG et al. (2012), that would be probably, either a misidentification, or a confusion with a sample from another country. L. schraderi is present in Madagascar, in Southern and tropical Africa: Ethiopia, Kenya, Malawi, Mozambique, Rwanda, South Africa, Swaziland, Tanzania, Uganda, Zambia and Zimbabwe. In those areas, L. schraderi is found in high altitude such as in Reunion island. CROUCH et al. (2011) specify that in South Africa at the Cape Province, this species can be found until to 2 300 m of altitude. It is then much smaller, lithophyt and can easily be confused with Grammitis poeppigiana (Mett.) Pic. Serm. which is another Polypodiaceae present in this region. In Reunion island, L. schraderi would be present only in the A. heterophylla forest located at the « Rivière de l’Est » bottom near the Piton de la Fournaise volcano. This forest offers an important floral diversity with numerous protected or endangered species. But, this particular vegetation is submitted to fire risks in relation with human activities (Fig. 3a), and to the occurrence of cattle in this part of the Reunion National Park (Fig. 3b). Thus, precautionary measures are needed for the protection of L. schraderi and more generally of the whole local vegetation. Cahiers scientifiques de l'océan Indien occidental 5, 2014: 21-26. 25 CONCLUSION The substantial prospecting work realized by Th. Cadet continues today to serve as the basis of the studies on Pteridophytes flora in the Mascarene Islands. The present work allowed to add L. schraderi to the other ferns from Reunion island. However, real threats exist about both the single population of this taxon and the Reunion highlands which are yet well known as rich biodiversity reservoirs. Local authorities have to control the human activities in order to preserve this exceptional habitat in a sustainable way. 3a 3b Figure 3. – 3a) Photography of a volcano area after fire; 3b) Photography showing predation of Polypodiaceae by cattle in the area of L. schraderi. Scale bar = 10 cm ACKNOWLEDGEMENTS We wish to express our sincerest thanks to Pr. J. Smadja and Pr. A. Bialeki for their help to translate this paper from French to English. REFERENCES BADRÉ F., 2008. – In: Bosser J., Badré F. & Guého J. (Eds.), Flore des Mascareignes - La Réunion, Maurice, Rodrigues. Ptéridophytes. 1. Psilotacées à 26. Marsiléacées. 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