Bryophytes of St Helena, South Atlantic Ocean. 3
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Arctoa (2008) 17: 91-100 BRYOPHYTES OF ST HELENA, SOUTH ATLANTIC OCEAN. 3. SAINTHELENIA, A NEW GENUS OF BRACHYTHECIACEAE (BRYOPHYTA) МОХООБРАЗНЫЕ ОСТРОВА СВЯТОЙ ЕЛЕНЫ, АТЛАНТИЧЕСКИЙ ОКЕАН. 3. SAINTHELENIA, НОВЫЙ РОД МХОВ (BRACHYTHECIACEAE) M.S. IGNATOV1, M.J. WIGGINTON2, O.I. KUZNETZOVA3 & S. HUTTUNEN4 M.С. ИГНАТОВ1, М.Д. ВИГГИНТОН2, O.И. КУЗНЕЦОВА3, С. ХУТТУНЕН4 Abstract Brachythecium athrocladum (Mitt.) Paris, an endemic species of St Helena Is- land, South Atlantic Ocean, is re-studied by morphology and molecular markers, nr ITS region and chloroplastic trnL-F. Molecular markers independently indicate the position of the species in Brachytheciaceae subfamily Helicodontoideae, especially close to the genera Helicodontium and Clasmatodon. Common characters of the plants from St Helena with these genera are discussed. Resulting from these studies, the new genus Sainthelenia Ignatov & M. Wigginton is described, with a single species, confined in its distribution to this island. Резюме Brachythecium atrocladum (Mitt.) Paris, эндемик острова Святой Елены в южной части Атлантического океана, изучен в отношении как его морфологии, так и последовательностей ядерной (ITS) и хлоропластной ДНК (trnL-F). Оба молекулярных маркера независимо указывают на положение в подсемействе Helicodontoideae, и наиболее близко к родам Helicodontium и Clasmatodon. Обсуждается морфологическое сходство этих родов с растениями с острова Святой Елены. В качестве таксономического решения предложено выделение данного эндемичного для острова вида в род Sainthelenia Igantov & Wigginton. KEYWORDS: mosses, Brachytheciaceae, Sainthelenia, taxonomy, molecular phylo- genetics, ITS, trnL-F INTRODUCTION (1875) published it in Sect. Brachythecium. Paris The bryophyte collections of W.J. Burchell, (1900) later validated its placement in Brachyth- made on St Helena, South Atlantic Ocean, between ecium. 1805 and 1810 during his residence on the island, Brotherus (1925) in “Pflanzenfamilien...” include a small pleurocarpous moss that Mitten later overlooked this species, , and as this publication described as having “the habit of Homalothecium is still the only one that includes a worldwide clas- sericeum, but more rigid, and with a capsule ex- sification of the genus Brachythecium, its posi- actly corresponding to that of the section Brachy- tion within the genus remained unclear. thecium”. He noted that very little of this plant The only other known collections of this in- was gathered and that only one capsule was seen teresting species were made two hundred years by Burchell, who marked [the specimen] Hypnum later, in 2005, by one of the authors (MJW). athrocladum B., the name under which Mitten Brachythecium athrocladum looks quite odd com- 1 – Main Botanical Garden of Russian Academy of Sciences, Botanicheskaya, 4, Moscow 127276 Russia – Россия 27276 Москва, Ботаническая, 4, Главный ботанический сад им. Н.В.Цицина РАН; misha_ignatov@list ru 2 – 36 Big Green, Warmington, Peterborough PE8 6TU, U.K.; e-mail: [email protected] 3 – A.N.Belozersky' Research Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991 Russia – НИИ Физико-химической биологии им. А.Н. Белозерского, МГУ, Москва 119991 e-mail: [email protected] 4 – Laboratory of Genetics, Department of Biology, FI-20014 University of Turku, Finland; e-mail: [email protected] 92 M.S. IGNATOV, M.J. WIGGINTON, O.I. KUZNETZOVA & S. HUTTUNEN pared with the other known species of the genus, DISCUSSION and in order to clarify its taxonomic position, we The position of ‘Brachythecium athroclad- carried out a morphological and molecular study, um’ in the clade of Helicodontioideae and es- in particular with molecular markers that have pecially within the ‘oceanic-epiphytic’ group proved to be useful for Brachytheciaceae taxono- may look somewhat unexpected. Species of my (e.g. Huttunen & Ignatov, 2004; Ignatov & Clasmatodon, Helicodontium, Homalotheciel- Huttunen, 2002), as well as for other mosses and la and Remyella are epiphytes with erect cap- also many other groups of eukaryots. sules and usually strongly modified peristomes, METHODS and often with relatively short leaves and lam- The most variable loci in moss DNA, nr ITS inal cells. However, the group also includes and chloroplastic trnL-F, were studied. The pro- ‘Rhynchostegiella durieui’ which is character- tocols of PCR and sequencing was standard (as ized by its inclined capsule having the ‘perfect described, for example, in Gardiner et al., 2005), peristome’ that is commonly fully developed in and the program Nona with the Winclada shell epigeic and epilithic species. Rhynchostegiella was used for parsimony analyses (Nixon, 1999 durieui grows mostly on rocks (Hedenдs, 1992), a,b; Goloboff, 1994). The extracts from the sets and has a geographical range including islands of molecular data on the Brachytheciaceae already of the North Atlantic (Azores, Canaries, Ma- used in the analysis of Huttunen & Ignatov (2004), deira) and the Mediterranean Sea, and also Huttunen et al. (2007) and Huttunen et al. (2008) mountains in the oceanic regions of Atlantic were utilized as ‘testing chips’ to evaluate the re- Europe and North Africa. lationships of this enigmatic species. Similarly, ‘Brachythecium athrocladum’ grows on rocks and tree bases, i.e. is not a ‘true RESULTS epiphyte’, and also has an at least somewhat in- Molecular analysis of ITS and trnL-F are clined capsule which, however, has a slightly re- shown in the Fig. 1. duced peristome, with basal membrane of only 1/ Despite the rather low variation in the trnL-F 4 endostome length, narrow and narrowly perfo- sequences, the strict consensus tree resolved ‘Bra- rated segments, and no ciliae. The exostome teeth chythecium athrocladum’ in Brachytheciaceae are striolate below, and hygroscopic movements subfamily Helicodontioideae, and in the group are xerocastique (i.e. the teeth close the mouth especially rich in monospecific genera, many of when wet, and open when dry). Thus the degree which have a restricted distribution in oceanic re- of exostome reduction is similar to that in Helic- gions. The statistical support of the clades of the odontium capillare, a widespread South and Cen- trnL-F tree was, however, very low. tral American species which, however, has a sym- The ITS analysis gave almost the same topolo- metrical capsule and a xerocastique exostome that gy, though slightly differed due to a somewhat dif- is usually pale in colour. ferent species set (this was determined by the avail- The common morphological characters of ability of data). The high jack-knife support was members of the oceanic-epiphytic clade are un- found for some clades, including 92 for the Helic- known. Most of the representatives of the clade, odontioideae clade, thus supporting the ‘Brachyth- including Homalotheciella, Clasmatodon, Remy- ecium athrocladum’ position within this subfami- ella and Aerolindigia, have characters usually as- ly, and not in the Brachythecioideae. The group of sociated with epiphytic habitats: a variously re- ‘Brachythecium athrocladum’ plus Helicodontium duced peristome, erect perichaetial leaves and and Clasmatodon has only a very low support (53), large spores. The extent of peristome reduction and this clade was included in a broader clade with (or modification) is, however, very different – Homalotheciella, Remyella, Aerolindigia, ‘Rhyn- from moderate reduction in Helicodontium to chostegiella durieui’ and ‘Oxyrrhynchium pumi- ‘complete’ peristome development in ‘Rhyncho- lum’. The two latter taxa are shown in inverted com- stegiella durieui’, as described above. At the mas due to their distant position from the core taxa same time, Helicodontium has short and thick- of their respective genera (cf. Huttunen et al., 2007; walled laminal cells, whereas in ‘Rhynchostegiel- Aloign et al., submitted). la durieui’ they are fairly long. ‘Brachythecium Sainthelenia, a new genus of Brachytheciaceae 93 AB 96 90 83 84 99 100 99 83 78 81 87 61 65 92 100 57 78 53 Fig. 1. A: Strict consensus tree of 1143 shortest trees (L=128) found in parsimony ratchet analysis of trnL-F sequences (L=350; RI=1; CI=0); B: Strict consensus tree of 73 shortest trees (L=482) found in parsimony ratchet analysis of ITS sequences (L=1975; RI=1; CI=0); jackknife values calculated for 1000 replications are shown below branches. athrocladum’ would not be easy to confuse with ITS data they are similar and can be assumed as the latter species, as it has habit of ‘typical Rhyn- a closest relatives. chostegiella’, with leaves from lanceolate-trian- Although our molecular phylogenetic analy- gular base very longly acuminate, with length to sis indicates closely related genera, it does not link width ratio >3.5:1, laminal cells usually >15:1, ‘Brachythecium athrocladum’ to any particular and also it is dioicous. Clasmatodon and Helic- genus. Among the Helicodontioideae there are a odontium have dull plants with leaves composed few other genera, with just one or two species, of short cells, strongly reflexing in wet state so whose DNA has not yet been studied because they they for a long time were classified in Fabroni- are known only from old collections. African aceae or Myriniaceae. Blunt ovate leaves make Schimperella and South American Mandoniella Helicodontium quite distinct from ‘Brachytheci- are also in urgent need of molecular study. How- um athrocladum’, although in peristome struc- ever, both these genera have smooth setae which, ture, wide distribution in South America and by in addition to other