Willdenowia 43 – 2013 25

ÁNGEL BAÑARES BAUDET1*, AURELIO ACEVEDO RODRÍGUEZ2 & ÁNGEL REBOLÉ BEAUMONT3

Monanthes subrosulata, a new species of M. sect. Sedoidea () from La Palma, , Spain

Abstract Bañares Baudet Á., Acevedo Rodríguez A. & Rebolé Beaumont Á.: Monanthes subrosulata, a new species of M. sect. Sedoidea (Crassulaceae) from La Palma, Canary Islands, Spain. – Willdenowia 43: 25 – 31. June 2013. – Online ISSN 1868-6397; © 2013 BGBM Berlin-Dahlem. Stable URL: http://dx.doi.org/10.3372/wi.43.43103 Monanthes subrosulata (M. sect. Sedoidea) from La Palma, Canary Islands, Spain, is described as a species new to science and illustrated. Special attention is paid to the morphological characteristics that differentiate it from the other species of the section (M. anagensis and M. laxiflora), as well as from M. muralis (M. sect. Monanthes). Additional key words: Monanthes anagensis, M. laxiflora, M. muralis, , chorology

Introduction branched habit, never forming rosettes, and with their inflorescences arising from the tips of the axes. Monan­ After the recent treatment of the Moroccan species thes subrosulata, located in the south and south-eastern Monanthes atlantica Ball as surculosum Coss. parts of La Palma island, shares the above characters and (Mes & ’t Hart 1994; ’t Hart & Bleij 2003), the unequivocally belongs to M. sect. Sedoidea. The most Monanthes Haw. is confined to the Canary Islands and striking character to separate it from the other species of Ilhas Selvagens, two archipelagos that biogeographically the section is the presence of conspicuous bladder-cell comprise the Canarian Province in the Mediterranean idioblasts (papillae), especially on the leaves (usually in- Region (Rivas-Martínez 2009), previously known as part conspicuous and not protruding in M. anagensis and M. of the Macaronesian Region. A total of nine species and laxiflora), as shown in the species of M. sect. Monanthes, two heterotypic subspecies are endemic to the Canary Is- especially in M. muralis (Webb ex Bolle) Hook. f., a spe- lands, and only M. lowei (A. Paiva) P. Pérez & Acebes is cies that shares some similarities with of M. sect. located in the Ilhas Selvagens (Nyffeler 1992; Nyffeler Sedoidea by its ascending and tufted habit. 2003; Bañares 2008). Infrageneric classifications distinguish three (Nyf- feler 1992) or four (Sventenius 1960; Nyffeler 2003) Results and Discussion sections in Monanthes, all of them accepting M. sect. Sedoidea Svent. ex Nyffeler with two species: M. ana­ Monanthes subrosulata Bañares & A. Acev.-Rodr., sp. gensis Praeger and M. laxiflora (DC.) Bolle. These spe- nov. cies are genetically closely related (Mes & al. 1997) Holotypus: Spain, Canary Islands, La Palma, “Canal de and morphologically distinct from the other taxa of the Tigalate”, 425 m, Mar 2008, Á. Bañares & A. Acevedo genus, especially by their slightly subshrubby, diffusely 46878 (TFC; isotypus: B).

1 Departamento de Biología Vegetal (Botánica), Universidad de La Laguna, E-38271 La Laguna, , Canary Islands, Spain; *e-mail: [email protected] (author for correspondence). 2 Calle Abajo 49, E-38750 El Paso, La Palma, Canary Islands, Spain; e-mail: [email protected] 3 Parque Nacional Caldera de Taburiente, Centro de Visitantes El Paso, Carretera General Padrón 47. El Paso, La Palma, Canary Islands, Spain; e-mail: [email protected] 26 Bañares & al.: Monanthes subrosulata from La Palma, Canary Islands

Fig. 1. Monanthes subrosulata – A: ; B: leaves; C: leaf papillae; D: buds and ; E: petals and stamens; F: nectaries – Scale bars: A = 1 cm; B, D = 2 mm; C, E = 1 mm; F = 0.5 mm. – Drawings made from the holotype.

Latin description — Plantae suffruticosae, 5 – 15 cm altae. non pilosa, adusque papillosa, ad apicem acutiuscula. Axes ascendentes aut decumbentes, 2 – 3 mm in diametro, Inflorescentiae terminales, 4 – 10-florae, pedicellis glan- non pilosi, papillosi in partibus superioribus. Folia alter- duloso-pubescentibus, pilis 0.2 – 0.3 mm longis. Flores nanta, non rosulata vel subrosulata, elliptica, 10 – 13 mm (5 vel)6-meri, 3 – 5 mm in diametro. Sepala basaliter con- longa, 3.5 – 5 mm lata, 2.5 – 3.5 mm crassa, plerumque nata, lobis ovatis, 2.3 – 2.5 mm longis, 1.5 – 1.8 mm latis, centraliter et longitudinaliter sulcata in facie ventrale, plerumque non pilosis, dense papillosis in facie dorsale. Willdenowia 43 – 2013 27

Petala oblonga, 3 – 3.3 mm longa, 0.8 – 1.1 mm lata, gla- L., Schizogyne sericea (L. f.) DC., Sonchus bornmuelleri bra, apice acuto. Nectaria bilobata, valde unguiculata. Pit., and the lichen Stereocaulon vesuvianum Pers. Carpella 2.3 – 2.5 mm longa, 1.3 – 1.5 mm lata, non pi- losa, parce papillosa. Additional specimens examined (paratypes) — Spain, Canary Islands, La Palma: Cruz de la Mancha, Description — Suffruticose plants, diffusely branched, 250 m, NNE, Mar 2008, Á. Bañares & A. Acevedo 48685 5 – 15 cm tall. Axes ascending or decumbent, somewhat (TFC); sobre el canal de Tigalate, 425 m, NE, Apr 2012, tortuous, greyish, 2 – 3 mm in diam., without hairs, basally Á. Bañares & A. Acevedo 48689 (TFC). rugose and usually covered with whitish waxy platelets, distally (around leaves) with prominent and abundant pa- Related taxa — Monanthes subrosulata belongs to pillae. Leaves alternate, not rosulate to subrosulate, usu- M. sect. Sedoidea by having a perennial and diffusely ally clustered near tips of axes, dark green, abaxially with branched habit, leaves alternate, not forming rosettes, a reddish tinge along median portion, elliptic, 10 – 13 × with internodes somewhat elongate (leaves scattered 3.5 – 5 mm, 2.5 – 3.5 mm thick, mostly with a central along axes), inflorescences arising from tips of axes, longitudinal furrow ventrally, without hairs, completely flowers (5 or)6-merous, pedicels evenly arranged, pe­tals papillose, more prominently so at apex, apex somewhat oblong, and nectaries distinctly clawed. In addition, it acute. Inflorescences arising from tips of axes, of 1 or distinctly shares with the other species of the section axes 2 regularly branched thyrses, 4 – 10-flowered; pedicels generally covered with whitish wax platelets and leaves 4 – 10 mm, glandular-hairy, hairs 0.2 – 0.3 mm; buds glo- with a central longitudinal furrow ventrally. bose. Flowers (5 or)6-merous, 3 – 5 mm in diam. Calyx Monanthes sect. Sedoidea comprises two species: without hairs or with very few short glandular hairs; M. anagensis and M. laxiflora. M. anagensis is a single- sepals basally connate, lobes suffused with red-brown, island endemic from the eastern Anaga mountains in ovate, 2.3 – 2.5 × 1.5 – 1.8 mm, densely papillose abaxi- Tenerife. It is a very well-characterized plant by its alter- ally. Petals pale green suffused with red, oblong, 3 – 3.3 × nate, long and narrowly elliptic leaves. M. laxiflora is the 0.8 – 1.1 mm, glabrous, apex acute. Nectaries suffused most widespread species and also the most xeromorphic with red, bilobate, 1 – 1.2 × 1.5 – 1.7 mm, distinctly member of the genus. It occurs in La Palma, La Gomera, clawed, apically erose. Carpels pale green with a red- Tenerife, Gran Canaria, Fuerteventura, and . dish tinge, 2.3 – 2.5 × 1.3 – 1.5 mm, without hairs, slightly After its discovery and sole citation by Lems & Holz­ papil­lose. Flowering: March to May. apfel (1974) in La Palma, the species was neglected there by authors (Santos 1983; Nyffeler 1992; Hohenester & Illustrations — Fig. 1, 3. Welss 1993; Bramwell & Bramwell 2001), but its occur- rence in northern locations of that island is confirmed Distribution and ecology — South and southeastern parts here: near Garafía [La Palma: Barranco de Carmona, of the island of La Palma, Canary Islands, Spain. The May 2012, Á. Acevedo & Á. Rebolé 48687 (TFC)]; El species is locally common on cliffs and rocky walls in Mudo, Barranco de Magdalena, and also in the centre of northeastern and north-northeastern exposures at alti- the island inside the Caldera de Taburiente National Park tudes from 30 m to 570 m (Fig. 2). In the municipality from 300 to 800 m [La Palma: Brevera Macha, Caldera of Villa de Mazo it is found at Salto de Tigalate, 30 m de Taburiente National Park, 780 m, N, Mar 2008, Á. Re­ (UTM-WGS84: 28RBS226594); Cruz de la Mancha, bolé 48688 (TFC); La Estrechura, Caldera de Taburiente 250 m (UTM-WGS84: 28RBS226588); Canal de Ti- National Park, 380 m, NE, May 2012, Á. Bañares & A. galate, 450 m (UTM-WGS84: 28RBS225587); and Mon- Acevedo 48686 (TFC)] (Fig. 2). M. laxiflora is a very tes de Luna, 525 – 570 m (UTM-WGS84: 28RBS225590). well-defined taxon by its decussate, ovate to almost sub- In the municipality of Fuencaliente it is found at Los orbicular leaves, usually partly covered by a thick wax Quemados, 500 m (UTM-WGS84: 28RBS222550); layer. It is a very variable plant, and different forms, va- near Faro de Fuencaliente, 370 – 400 (UTM-WGS84: rieties, and closely related species have been described, 28RBS222538); Roque Orchilla, 305 m, (UTM-WGS84: such as the often distinguished M. microbotrys (Bolle & 28RBS222527); and Montaña del Mago, 410 m (UTM- Webb) Bolle from the eastern islands Fuerteventura and WGS84: 28RBS221534). It is usually established in Lanzarote (Bolle 1859, 1892; Bornmüller 1906; Praeger small holes exposed to humid north winds, associated 1932), but these taxa are included in the synonymy of M. with xerophytic plants of the Canarian white broom com- laxiflora (Nyffeler 1992). This variability – actually un- munities (Retamation rhodorhizoidis Del Arco & al. der study by the authors – is probably correlated with the 2009) in badlands of recent and historic lava fields. The different habitats where the species can be found: plants most common species found in these areas are from forested and northern locations are somewhat dif- da­vidbramwellii H. Y. Liu, Davallia canariensis (L.) ferent to those from arid zones where the species is well Sm., Euphorbia lamarckii Sweet, Kleinia neriifolia Haw., adapted with singular xeromorphic features. In fact, our Lavandula canariensis Mill., Retama rhodorhizoides recent discovery of M. laxiflora in La Palma exhibits this Webb & Berthel., Rubia fruticosa Aiton, Rumex lunaria same feature, with plants from northern locations differ- 28 Bañares & al.: Monanthes subrosulata from La Palma, Canary Islands

Fig. 2. Distribution of Monanthes subrosulata (, ), M. laxiflora (, ), M. muralis (, ã, ) and M. polyphylla subsp. amydros (, ã, ) on the island of La Palma. Symbols common to more than one taxon indicate co-occurrence of those taxa. Willdenowia 43 – 2013 29 ent to those from the central caldera of the island. Monanthes subrosulata differs from M. anagensis by having axes papillose, usually covered with white platelets, leaves differently sized and entirely papillose, pedi- cels glandular-hairy, sepals without hairs and dorsally papillose, petals glabrous, nectaries differently sized, and carpels slightly papillose. From M. laxiflora it differs by having a less robust habit, leaves alternate, elliptic, differently sized and en- tirely papillose, pedicels glandular- hairy, sepals and petals without hairs, and nectaries differently sized (see Table 1, mostly based on Nyf- feler, 1992). Among the rest of the species of the genus, only Monanthes muralis (M. sect. Monanthes) can be com- pared with the new species by hav- ing typically a suffruticose habit, axes ascending or decumbent, and axes, leaves, and sepals papillose; M. muralis is distributed in the is- lands of El Hierro and La Palma. M. subrosulata differs mainly by - hav ing a more robust and non-rosulate habit, axes without hairs and cov- ered with white platelets, leaves larger, without hairs, ventrally with a central longitudinal furrow, calyx without hairs, petals glabrous, and carpels scarcely papillose. Fig. 3. A – B: an individual of Monanthes subrosulata at the type locality (Spain, La Palma, “Canal de Tigalate”, 425 m) on 1 Apr 2006. – Photos by Á. Bañares Baudet. Remarks — After revision of the genus Monanthes (Nyffeler 1992), only two species stum & al. 2012). Extensive hybridization is known to were known on the island of La Palma: M. muralis (also occur among the taxa in the Canarian Crassulaceae present in El Hierro) and M. polyphylla subsp. amydros (Praeger 1932; Bañares 1990, 2007; Voggenreiter 1999). Nyffeler (also present in La Gomera; see Bañares 2008). Hybrids of the Crassulaceae species are represented in With the present study, two species are added to the flora small numbers or as single plants around their parents, of La Palma: M. laxiflora (known from all islands except usually in newly created habitats but also in co-occur- El Hierro) and the newly described M. subrosulata. ring original locations occupying the same ecological Recently, Nyffeler (1995) extensively illustrated that niche. Flowering coincidence, population proximity (up the genus Monanthes forms a comparium or a syngamo- to 50 m), and the presence of efficient pollinators (Hy­ deme (a group of taxa capable of hybridizing with one menoptera) facilitate the establishment of hybrids that another), a well-known phenomenon in the Crassula­ are easily recognized in growth form and detailed mor- ceae; thus special attention has been paid to rule out the phology (for the genus Aeonium Webb & Berthel. see possibility that M. subrosulata could represent a hybrid. Voggenreiter, 1999). Hybridization processes among species are a com- References on the chorology of the species of Monan­ mon feature in the Canarian flora as the increasing dis- thes in La Palma (Santos 1983; Nyffeler 1992; Bañares turbance of the natural habitats by human activities (e.g. 2008) and a recent survey in the field revealed two sites roads, waterways) reduces ecological separation and with co-occurring taxa (showing a close connection natural barriers that originally played an important role among individuals): (1) M. laxiflora – M. polyphylla sub- in the speciation process (Brochman 1984; van Heng- sp. amydros in the central part of La Palma at La Es- 30 Bañares & al.: Monanthes subrosulata from La Palma, Canary Islands

Table 1. Comparison of morphological characters of the species of Monanthes sect. Sedoidea and M. muralis. Monanthes laxiflora Monanthes anagensis Monanthes subrosulata Monanthes muralis Axes papillose, without hairs not papillose, without hairs papillose, without hairs papillose, glandular- hairy with whitish waxy platelets without platelets with platelets without platelets

Leaves decussate, not rosulate alternate, not rosulate, some- alternate, not rosulate to subro- alternate, rosulate what clustered sulate, usually clustered elliptic or ovate to suborbi- narrowly elliptic elliptic obovate cular 5 – 12 × 3 – 8 mm, 3 – 6 mm 9 – 18 × 2 – 4 mm, 2 – 4 mm 10 – 13 × 3.5 – 5 mm, 2.5 – 6 – 10 × 3 – 4 mm, thick thick 3.5 mm thick 2 mm thick furrowed ventrally furrowed ventrally furrowed ventrally not furrowed not papillose or scarcely so not papillose papillose papillose with whitish waxy platelets without platelets without platelets without platelets Pedicel glabrous or glandular-hairy glabrous or scarcely glandu- glandular-hairy glandular-hairy lar-hairy hairs ≤ 0.2 mm hairs ≤ 0.05 mm hairs 0.2 – 0.3 mm hairs ≤ 0.7 mm Sepals papillose dorsally not papillose papillose dorsally papillose dorsally with or without glandular without hairs or scarcely without hairs glandular-hairy hairs hairy Petals 2.9 – 4.4 ×0.9 – 1.4 mm 3.4 – 4.6 × 1.1 – 1.6 mm 3–3.3 × 0.8 – 1.1 mm 2.9 – 4.1 × 0.5 – 0.7 mm slightly glandular-hairy slightly glandular-hairy glabrous glandular-hairy Nectaries clawed clawed distinctly clawed distinctly clawed trechura, 380 m, close to the Caldera de Taburiente Na- Acknowledgements tional Park (known as producing hybrids in La Gomera, see Bañares 1990); and (2) M. subrosulata – M. muralis The authors are indebted to Carlos Rodríguez for pro- in southeastern­ La Palma, but hybrids between these ducing the drawings and Juana Pérez for translating the parents have not actually been found in La Palma. Some description into Latin. We thank Vicente García López, close populations of M. muralis and M. polyphylla subsp. Gerard Latorre, and Daniel González for providing cho- amydros are also found inside the central Caldera, but the rological data on Monanthes laxiflora. plants are not living together (Fig. 2). Monanthes subrosulata is located in southern and southeastern La Palma at altitudes from 30 m to 570 m, References and their populations occupy a total of 37.5 km2 (Extent of Presence, see IUCN Standards and Petitions Subcom- Bañares Á. 1990: Híbridos de la familia Crassulaceae en mittee 2010) (Fig. 2). M. muralis is distributed in western, las Islas Canarias. Novedades y datos corológicos II. southern, and southeastern La Palma at altitudes from – Vieraea 18: 65 – 86. 350 m to 1200 m, and it is found co-occurring with the Bañares Á. 2007: Híbridos de la familia Crassulaceae en uppermost populations of M. subrosulata (separated by las Islas Canarias. IV. – Vieraea 35: 9 – 32. only c. 20 m) in Montes de Luna (570 m, UTM-WGS84: Bañares Á. 2008: Taxonomic and nomenclatural notes on 28RBS225590). Other close populations of these species Crassulaceae of the Canary Islands, Spain. – Willde- are found in the south of La Palma, around Los Quema- nowia 38: 475 – 489. dos (T. M. Fuencaliente), but without connection among Bolle C. 1859: Addenda ad floram Atlantidis, praecipue individuals (separated by 700 – 900 m). No other species insularum Canariensium Gorgadumque. – Bonplan- have been found within the distribution of the new spe- dia 7: 238 – 246. cies so as to consider the possibility of a hybrid origin. Bolle C. 1892: Florula Insularum olim Purpurasiarum, M. laxiflora and M. polyphylla subsp. amydros are geo- nunc Lanzarote et Fuerteventuracum minoribus Is- graphically and ecologically separated, and their nearest letas de Lobos et la Graciosa. – Bot. Jahrb. Syst. 14: populations are considerably remote from the part of the 230 – 257. island occupied by M. subrosulata, ranging from 20.6 km Bornmüller J. 1906: Zur Gattung Monanthes. – Repert. and 17.5 km distant, respectively. Spec. Nov. Regni Veg. 3: 26 – 27. Willdenowia 43 – 2013 31

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