Nova Hedwigia 56 1—2 263—271 Stuttgart, Februar 1993 Orthotrichum ibericum sp. nov., a new moss from the Iberian Peninsula by Francisco Lara and Vicente Mazimpaka Departamemo de Biotogia (Botanica), Facultad de Ciencias, Universidad Autonoma de Madrid Cantoblanco, E-28049 Madrid With 4 figures and I table Lara, F. & V. Mazimpaka (1993): Orthotrichum ibericum sp. nov., a new moss from the Iberian Peninsu la. - Nova Hedwigia 56: 263-271. Abstract: A new Orthotrichum is described from the mountains of the central-western zone of the Iberian Peninsula. The new species, characterised by a long seta, exserted capsule and extreme reduction of the peristomc, is included in the subgenus Phaneroporum Delogne, section Leiocarpa Mol. Its relationships with some members of this section are discussed and its ecology and distribution in the area are com mented. Resumen: Se describe un nuevo Orthotrichum procedente de las montanas del centro-oeste de la Peninsu la Ibfrica. La nueva especie, caracterizada por su larga seta, capsula exerta y extrema reduccidn del peristoma, se incluye en el subgenero Phaneroporum Delonge, section Leiocarpa Mol. Se discute sus relaciones con algunos miembros de esta secci6n y se comenta su ecologia y distribucidn en el area. Introduction While carrying out a study on epiphytic bryophytes in oak woods of the marcescent Quercus pyrenaica Willd. in the Iberian Central Range, we found some Orthotri chum specimens with a rudimentary peristome. Assuming that this was due to acci dental damage, we included them in O. speciosum Nees in Sturm. However, as the number of studied woods and samples increased, it appeared that the "anomalous" features observed in the first samples were consistent and there were macroscopic features that afforded a clear segregation from O. speciosum. Later study of the dis tribution of this material within the Central Range of the Iberian Peninsula also sug gested its separation at specific level. Description Orthotrichum ibericum Lara & Mazimpaka, sp. nov. Fig. 1-3 Ut Orthotrichum speciosum Nees in Sturm, quo differt exostoma imperfecto, occulto vel vix annulo emergente, generaliter sine endostomae vestigiis; capsula 8-striata, cum striis parvis sed bene impressis, aurantiis vel fuscis, capsulae orem contrahentibusque. 0O29-5035/93/OO56-0263 $2.25 © 1993 J. Cramer in der Gebruder Bornlraeger Vcrlagsbuchhandlung, D-1000 Berlin - D-7000 Stullgan 263 HolotypE: SPAIN, Avila: Serranillos, oak-wood near the village, ca 1250 m a.s.l., 3OTUK36, corticolous on Quercus pyrenaica Willd., 1 November 1991, F. Lara & P. Ramirez, MA-Musci 12262. (Isotypes in ALTA, BCB, and authors herbarium). Material examined (paratypes): PORTUGAL: Beira Baixa, Manteigas, carretera al Poco do Inferno, 900 m, 29TPE27, 5-XII-1988, R. Garilleti & F. Lara, MA-Musci 12263. SPAIN: Avila, Candeleda, Garganta de Santa Maria, 1100 m, 30TUK15, 3-V-1991, F. Lara & P. Ramirez, MA-Musci 12264; Poyales del Hoyo, Fuente del Roble, 600 m, 3OTUK15, 4-V-1991, F. Lara & P. Ramirez, MA-Musci 12266; La Adrada, Los Pajonales, 1000 m, 30TUK66, 19-XI-I988, R. Garilleti & F. Lara, MA-Musci 12265; Navalonguilla, melojar cerca del pueblo, 1100 m, 30TTK86, 3-XI-1991, F. Lara & P. Ramirez, MA-Musci 12267; Caceres, Hoyos, Sierra de San ta Olalla, 600 m 29TPE94, 3-1-1989, F. Doinguez, R. Garilleti, F. Lara & F. Marti nez, MA-Musci 12268; Humilladero, corticicola sobre Ios castaflos, 800 m, 30STJ9871, 9-XI-1979, M.C. Vierra, MA-Musci 5127 (as Orthotrichum speciosum Sturm); Madrid, La Herreria (El Escorial), epifito sobre tronco de melojo, 900 m, 30TUK0191, 12-11-1989, J.M. Lopez & C. L6pez, MA-Musci 9464 (as Orthotrichum speciosum Nees); Salamanca, Navasfrias, melojar del rio AgUeda, 950 m, 29TPE86, 31-XII-I988, F. Dominguez, R. Garilleti, F. Lara & F. Martinez, MA-Musci 12269. Plants 1.0-2.5 cm long, in olive-green or brown-green mats of 1-5 cm diameter. Stems irregularly branched, often with branch tips subsecund. Leaves rigid, erect or erect-appressed and somewhat sinuose when dry; patent, spread or squarrose when moist. Costa strong but becoming slender near the apex, leaves keeled below to almost plane above. Margin recurved in the lower half, revolute in the upper, plane irregularly crenate near the apex and always unistratose. Upper leaves (3.0)3.5-4.0 mm long, lanceolate to ovate-lanceolate, apex acuminate often longly apiculate, rarely acute. Mid and lower leaves smaller and (2.0)2.5-3.0(3.5) mm, lanceolate to ovate-lanceolate, apex acute or apiculate. Upper cells elliptic or irregularly rounded, (8)10-13(18) fim wide and (9)11-18(20) /im long, with strongly incrassate walls; mid cells more frequently rounded, 9-12 x 10-17 /an, with incrassate walls. In both cases, with 1-2(3) simple (not forked), conical and, in general, scarcely prominent papillae per cell. Basal cells elongate-rectangular, 30-70/im long and 10-12//m wide, with variously incrassate walls, sinuose to nodu lose, rarely smooth; in the marginal region, cells shortly rectangular or quadrate, without papillae, except in upper marginal cells. Autoicous. Setae 1.25-2.25 mm, spirally twisted when dry, vaginula naked or with a few, long and finely papillose hairs. Capsules (1.6)2-2.5 mm, exserted or rarely emergent, cylindric or more or less longly ellipsoid, gradually narrowed to the seta through a long neck 0 '8-1 '5 mm, the mouth contracted when dry. In mature and peristome bared specimens, capsule mouth turning closed and characteristically starled when dry; when moist, capsule mouth non contracted or, rarely, constriction affecting only the upper part of the urn, just beneath the mouth. Conspicuously 8 ribbed 1/10 to 1/6 the length of the capsule; striae formed by 4-5 files of well differ entiated exothecial cells, broadly rectangular with yellow to orange thick walls, making the striate zone turn dark brown in old and dry capsules; other exothecial 264 B 1mm ,/V Fig. 1. Orthotrichum ibericum. A - mature capsule, dry. B - mature capsule, wet. C - old capsule, wet. D - inmature capsule with operculum. E - calyptra. F - habit, wet. 265 Fig. 2. Onhotrichum ibericum. A - uppermost leaves. B - basal leaves. C - leaf cells at different levels. D - cross sections of upper leaves, showing leaf margin at different levels. E - cross section of a portion of leaf above middle. F - different shapes of leaf apex. 266 IQOum Fig. 3. Orlholricfium ibericum. A - exostome with protruding teeth. B - exostome with immersed teeth. C - peristome with exostome and endostome remains. D - exothecial cells of striae at capsule apex. E - stomate. 267 cells fine, linear to narrowly rectangular, with hyaline and less thickened walls. Stomates phaneroporous, in the middle or lower half of the capsule, never in con tact with the striae. Peristome imperfect and generally single. Exostome scarcely de veloped, formed by 8 bigeminate teeth each with only 2-7 cells, in general densely papillose, immersed or shortly protruding from the rim. Endostome lacking or rare ly represented by 8 imperfect segments, each of them with 2-5 uniseriate cells, less papillose than exostome teeth. Preperistome lacking. Operculum very abruptly rostrate when dry, more gradually contracted to rostrum when moist; rostrum 0.35-O.SO mm, with rounded apex. Calyptrae mitrate, longly conic, plicate, abun dantly hairy, with hairs lightly papillose, ending in a dark point ca 1 mm. Spores lightly papillose, (14)16-25(30) urn. Ecology and distribution Orthotrichum ibericum has been repeatedly found in pioneer communities coloniz ing trunks of young or mid-aged oak trees of Quercus pyrenaica Willd., more rarely in bases and higher branches; exceptionally on chestnut-trees (Castanea saliva Mil ler) and ashes (Fraxinus angustifolia Vahl.). It grows together with other xerophilous and pioneer bryophytes, among which Frullania dilatata (L.) Dum. and many Orthotrichum species namely O. striatum Hedw., O. acuminatum Philib., O. rupestre Schleich. ex Schwegr., O. tenellum Bruch ex Brid., O. affine Brid. and O. pumilum Sw. are most frequent. Up to now, O. ibericum has been found solely in the western half of the Central Range and in Sierra de Guadalupe (fig. 4). It is most common in the northern slope of Sierra de Gredos, where it has been collected on 65-86% of the marcescent oak trees with a diameter less than 50 cm; on the southern slope, it is found on 2-25% of all the sampled trees. At the W of Gredos it becomes rarer, with a mean frequen cy of 2-3%, reaching 5-10% in Serra da Estrela. In the eastern zone of the Central Range, the occurrence frequencies fall abruptly and quickly: only 2% along the western border of Sierra de Guadarrama. Other ranges of the western half of the Iberian Peninsula (Toledo Mountains, Sierra Morena, Sierra Segundera) have been explored, without finding any record of this moss. In northern and eastern montane zones of the Iberian Peninsula, similar ecol ogical sites are occupied by O. speciosum. Both mosses seem to be absent in the southern territories of the Iberian Peninsula, excepting one O. speciosum record from Sierra Nevada. The distribution of both species of Orthotrichum in the Iberian Central Range (fig. 4) is significant, as it reveals a clear geographic substitution. Both require high preci pitation (>600 mm/year), but O. speciosum seems to be restricted to eurosiberian zone and to submediterranean environments with attenuated summer drought, whereas O. ibericum occurs in areas subjected to a more prolonged and intensive summer drought. Thus, both taxa seem to be ecological vicariants, adapted to dif ferent bioclimatic conditions. 268 Fig. 4. Distribution of Ortholrichum ibericum (•) in the Iberian Peninsula and occurrence of O. specio sum (A) in the Central Range. SA - Sierra de Ayllon. ES - Serra da Estrela. GA - Sierra de Gata. GR - Sierra de Gredos. GU • Sierra de Guadarrama. SG - Sierra de Guadalupe (Toledo Mountains). Discussion Orthotrichum ibericum is an epiphyte easy to identify on the account of the follow ing characters combination: I - capsule exserted, 2 - stomates phaneroporous, 3 - rudimentary peristome, 4 - cap sule mouth strongly contracted, with short but well marked, orange to dark brown striae. The last feature is macroscopic and affords recognition of the taxon in the field (under dry conditions). These features together with exostome teeth densely papillose and relatively opaque, though not recurved because of their scarce development, suggest its inclusion in the section Leiocarpa Mol. of the subgenus Phaneroporum Delogne. As for morfological affinities, this moss shows, precisely, closer relationships with other members of this section, chiefly with O. speciosum and O. acuminatum Philib. (table 1). Like wise, Vitt (personal communication) pointed out some resemblance with the north amcrican O. keeverae Crum & Anders. The long seta of O. ibericum as well as other consilient characteristics (calyptra densely hairy, big spores, etc.) suggest a close taxonomic relationship between the newly proposed taxon and O. speciosum. Differential features of the former could be considered as derived from those of O. speciosum, as a result of an effective 269 Table 1. Comparison of some Orthotrichum species of section Leiocarpa Mol. adaptation to a drier environment. In fact, reduction of the diplolepidous peristome in the genus Orthotrichum is a common evolutionary trend, related with specializa tion to xeric habitats (Vitt 1971, 1973, 1981). In the xerocastique O. speciosum, spore release takes place after rain events and du ring the drying out phase. However, the new moss has always appeared with cap sules open and spores spread over its gametophytes during and just after raining, thus it is hygrocastique. Patterson (19S3) reported hygrocastique mechanisms of spore release in epiphytic mosses with perfect peristomes and Mueller & Neumann (1988) synthetised available information on structure and function of such peri stomes. The originality of O. ibericum lyes in the fact that the whole urn takes con trol of spore dispersal, as functional loss of peristome is compensated by capsules movements which induce its mouth closure or aperture. In fact, the strong striation of the upper portion of the capsule acts as the morphological regulator, opening the capsule under wet conditions and closing it under dry ones. Thus, among other dis- 270 similarities, O. ibericum is different from O. speciosum in two points not necessary correlated: lack of a functional peristome and hygrocastique character. As we have commented above, geographical areas of both taxa in the Iberian Peninsula are sub jected to different climatic conditions: O. speciosum occurs in mesic forests, where as O. ibericum area is more xeric, due to its long and very dry summer. Therefore, even though factors influencing a new taxon appearance are diverse, complex and often not fully understood, it might be hypothesized in accordance with Vitt (1971, 1981) that peristome reduction or loss in the new moss is a consequence of adapta tion to a xeric environment, where there are no selective pressures to keep a func tioning peristome. As for the hygrocastique character, it could be related with selec tive pressures on spore dispersal and germination in a mediterranean environment with a very irregular regime of precipitation. Acknowledgments Dr. Vitt revised the material and confirmed the new taxon. We acknowledge him with our deepest thanks for this and for his helpful comments of the manuscript. We also are grateful to Pablo Ramirez for his contribution to the new moss collection and to Elena Bermejo for her drawings. References PATTERSON, P.M. (1953): The aberrant behavior of the peristome teeth of certain mosses. - Bryologist 56(3): 157-159. MUELLER, D.M.J. & A.J. NEUMANN (1988): Peristome structure and the regulation of spore release in arthrodontous mosses. - Advances in Bryology 3: 135-158. VITT, D.H. (1971): The infrageneric evolution, phylogeny, and taxonomy of the genus Orthotrichum (Musci) in North America. - Nova Hedwigia 21: 683-711. VITT, D.H. (1973): A revision of the genus Orthotrichum in North America, North of Mexico. - Bryophyt. Biblioth. 1: 1-208, pis. 1-60. VITT, D.H. (1981): Adaptative modes of the moss sporophyte. - The Bryologist 84(2): 166-186. 271 View publication stats