Journ. Hattori Bot. Lab. No. 71: 165- 173 (Jan. 1992)

ORTHODONTOPSIS, A NEW GENUS OF (MUSCI) FROM SOUTHERN SIBERIA, USSR

1 2 MICHAELS. IGNATOV AND BENITO C. TAN

Among the many bryophyte collections made recently by the senior author from the Altai mountain in southern Siberia, USSR, is an Orthodontium-like which proves to be new to science. The specimens were collected from a rotten log with Dicranum fragi/ifo/ium Lindb., Lepidozia reptans (Hedw.) Oum., Lophozia ventricosa (Dicks.) Oum. in subalpine Pin us sibirica forest on a south-facing slope at an elevation of 2100m in close proximity to the permafrost area. It grows also on soil under the roots of fallen trunks. The locality is Ayulyuyuzyuk Creek, Karakem River Basin in Central Altai (50 30'N - 89 lO'E). Later, Dr. L. V. Bardunov of Irkutsk Herbarium showed us his collection of the same species from Western Sayan Mt. adjacent to the Altai range, also from rotten wood at an elevation of 1700 m elevation in a Pin us sibirica and Larix sibirica forest. Both specimens have strong resemblance to species of Orthodontium, especially when dry. The gametophytes are erect, with loosely tufted habit, lanceolate-linear leaves, and the sporophytes are terminal in position. However, under the microscope, the leaf areolation is like a with rhomboidal to rectangular cells, except at the well developed leaf border. The capsule which is erect and also Orthodontium-like in shape and appearance has only a highly reduced endostome consisting of short and slender processes that are deeply inserted at the mouth and without a basal membrane (Plates 3 & 4). No remnants of an exostome is observed. Using the worldwide keys and descriptions contained in Brotherus ( 1924) and other regional floras or monographs, such as Fleischer ( 1902- 1904), Sainsbury (1955), Nyholm (1958), Ochi (1959), Lawton (1971), Gangulee (1974), Smith (1978), Crum and Anderson (1981), Koponen and Norris (1985), and Noguchi ( 1988), we are led to Orthodontium Schwaegr. (including Stableria Lindb.) or Mieli­ chhoferia Nees & Hornsch. The genus Orthodontium Schwaegr. has been treated in a worldwide monograph by Meijer (1952), who accepts eight species distributed chiefly in temperate oceanic and tropiCal mountainous climates, especially in the southern hemisphere. It is quite surprising therefore to find an Orthodontium-like moss in southern Siberia where there is a strong continental climate. Our Siberian moss is similar to species of Orthodontium in many respects: epixylic habitat, overall plant size, the branching pattern, the presence of fragile or deciduous branches, agreement in leaf outline, a spreading foliation with leaves often 3- 4 times twisted or flexuose, the costal anatomy, the autoicous condition and the papillose

1 Main Botanical Garden, Botanicheskaya 4, Moscow, USSR 127276. 2 Farlow Herbarium, Harvard University, 22 Divinity Avenue, Cambridge, Massachusetts, USA 02138. 166 Journ. Hattori Bot. Lab. No. 71 I 9 9 2 spores. All of these are strong indications that the new taxon may have evolved in isolation from an ancestral Orthodontium . However, all species of this genus, including the four presently known in northern hemisphere, namely, 0. lineare Schwaegr., 0. pellucens (Hook.) B. S. G ., 0. gracile Schwaegr. ex Bruch & Schimp. and 0. infractum Dozy & Molk., differ significantly from the Siberian moss in having ( 1) stems with a central strand, (2) unbordered leaves, (3) mostly elongate to linear laminal cells, and ( 4) a double peristome, albeit in various states of reduction. Obviously, to place the specimens in Orthodontium would require a basic alteration of its generic concept. The well differentiated and often bistratose leaf borders of the Siberian moss need additional comment. Consisting of 2 to 3 rows of elongate-linear cells, the bistratose borders occur on nearly all leaf margins except at the apex and proximal base. Within the subfamily Orthodontioideae, this is undoubtedly a disparate, autapomorphic char­ acter. We also compared this intriguing moss with the northern hemisphere species of Mielichhoferia and Asiatic members of Schizymenium Harv. ex Hook., the two genera of subfamily Mielichhoferioideae defined principally by the presence of a single peristome either representing a reduced exostome or endostome (see also Shaw 1985). Among those studied, the peristome structure of M. macrocarpa (Hook. ex Drumm.) Bruch & Schimp. (see Shaw & Crum 1984), M. himalayana Mitt. and S. javanicum (Broth. ex Fleisch.) Shaw come closest in their overall structural morphology. Nonetheless, the highly reduced, single structure observed in Mielichhoferia is the exostome (Shaw 1985) and not the endostome (cf. Shaw & Rohrer 1984) as is the case of Siberian moss. In Schizymenium javanicum, the single and endostomial peristome has a low basal membrane with remnants of cilium formation, and is quite different from that seen in our undescribed moss. It would appear that in bryaceous genera reduction of peristome into a single structure, either exostomial or endostomial, has evolved independently several times in separate lines of evolution. To force the Siberian moss into one of these two genera on the basis of a single peristome would create paraphyletic genera (see Fig. 1). In addition, species of Mielichhoferia and Schizymenium differ fundamentally from the Siberian moss in having ( 1) a caespitosely branching habit, (2) uniformly ovate­ lanceolate (rarely oblong to narrowly lanceolate) leaves, (3) laterally or basally located perichaetia, (4) thick, pyriformis capsules with well developed annuli, and (5) smooth to slightly papillose spores. In contrast, the moss under study has terminal inflores­ cences, although a few may grow on short lateral branch; and moreover, many

PLATE l. Orthodontopsis bardunovii (based on holotype). A. Plant habit in wet condition; Al. The same plant with detached branches; A' : diagramatic scheme of the same plant showing position of gametangia; A2: autoicous branch with a secondary branch bearing antheridia in leaf axil (A2'). B. Upper portion of stem with leaves mostly removed to show the terminal and lateral archegonia. C. Branch with an enlarged, fertilized archegoniun. D. Leaves in dry condition. E. Stem leaves. F. Stem cross-section. G. Axillary hairs. H. Rhizoids. M. S. IGNATOV & B. C. TAN: Orthodontopsis, a new genus of Bryaceae 167

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\H G 168 Journ. Hattori Bot. Lab. No. 71 I 9 9 2 ~~ ~ c M. S. IGNATOV & B. C. TAN: Orthodontopsis, a new genus of Bryaceae 169

3 archegonia are seen scattered along the stem without subtending perichaetial leaves • Furthermore, its capsular wall is thin, the annulus is not apparent, and the spores are clearly papillose (see Plate 4c). The exothecial cells of Mielichhoferia and Schizym­ enium also are rounded, polygonal, quadrate to short rectangular in shapes, and with thick walls, whereas our problematic moss, like species of Orthodontium, has exothecial cells that are rectangular and oblong in shapes and have thin walls. Additionally, species of Mielichhoferia are epilithic and none is primarily epixylic on rotten wood, like this Siberian moss. We sent a specimen, labelled "Orthodontium sp.", to Dr. H. Ochi for his taxonomic opinion. His reply (pers. comm., 1991) was, "I have no name. I also tried Mielich­ hoferia, but the species of this genus all have a different leaf shape, and their leaves have long cells and no borders.... " We believe that our moss specimen has sufficiently distinctive combinations of characters and that it deserves a generic recognition setting it apart from Orthodontium sensu Meijer ( 1952) and Mielichhoferia and Schizymenium sensu Shaw & Crum ( 1982, 1984) and Shaw (1985). A less satisfactory decision would be to describe it as a new subgenus in Orthodontium or Bryum. But to do so would only make the two contending genera polyphyletic and blur the traditional definition of genera in the family Bryaceae. We propose, therefore, a new monotypic genus to accomodate this unique Siberian moss pending a phylogenetic revision of bryaceous genera on a worldwide basis.

Orthodontopsis bardunovii lgnatov & Tan, gen. et spec. nova. Plates 1- 4. Caulis valde ramificans fasciculo centrali nullo. Folia basalia diminuta, versus apicem accrescentia, superiora linearia, breviter acuminata, margine ad apicem parce crenata, limbo bistratoso e cellulis bi­ triseriatis formato. Costa infra apicem folii evanescens. Cellulae laminorum rhomboideae, 1: 2-4. Autoicous. Perichaetia terminalia, rarius lateralia aeque ac archaegonia nuda lateraliter disposita. Capsula subcylindrica, pallida, membranacea. Operculum humiliter conucum obtusum. Annulus et peristomum extemum desunt. Peristomii intemi 16, perforati vet integri, membrana peristomii nulla. Sporae papillosae. in tufted clusters, forming mat or growing intermixed among other bryophytes. Stems 3- 5 mm long, 0.2--0.3 mm wide, without a central strand and a differentiated cortical layer, branched mostly at base, with fragile branches equal in length to the main stem or 2-3 times shorter. Rhizoids well developed, mostly colorless, with a few colored ones, profusely branched, ea. I0-15µm wide, at times only 3-4µm wide, thin-walled, smooth, rarely verrucose. Leaves dull green, spreading when moist, flexuose to strongly spiral-twisted when dry,

PLATE 2. Orthodontopsis bardunovii (based on holotype). A- J. Leaf cross-sections; K, L: leaves; Kl, K2, K3, LI & L2: leaf cells (position on the leaf indicated by arrows); M: medial lamina! cells.

3 Though a rare character, the lateral position of naked moss archegonia seems to have taxonomic values. So far, it is known in Splachnobryaceae and some members of Splachnaceae, namely Aplodon wormskjoldii (Homem.) R. Brown and Sp/achnum sphaericum Hedw. (Chopra & Sheet 1974, A. Koponen 1981). 170 Journ. Hattori Bot. Lab. No. 71 I 9 9 2 (/~ B

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PLATE 3. Orthodontopsis bardunovii (based on holotype). A, B. Single peristomes, the endostome; C-G: endostomial segments; H- J: capsules, with operculum (I', J) represent wet condition). narrowly oblong-lanceolate to lanceolate-linear, (2) 2.5-3 (5)mm long, and about 0.4--0.6mm wide, sometimes folded at base, much smaller in dimension near base of stem, about I mm long; costa ends in a few cells below the acute apex, rarely percurrent or excurrent, in cross-section showing various degrees of stereid development depending on the position of the leaf on stem axis and the thickness of the walls of surrounding abaxial and adaxial epidermal cells, commonly with one dorsal stereid band, at times without, and no guide cells; margins weakly denticulate near apex, otherwise nearly entire, with rather conspicuous borders nearly all around and in most leaves, consisting of 2- 3 ( 4) rows of elongate to linear cells in (I) 2- 3 layers in cross-section; lamina] cells in the upper part of the leaf short-rhombic, 35- 40 µm long and 15- 20 µm wide, about 2- 2.5 : I in 1: w ratio, at the middle level shortly oblong, intermixed with numerous cells of M. S. lGNATOV & B. C. TAN: Orthodontopsis, a new genus of Bryaceae 171

PLATE 4. SEM pictures of sporophyte of Orthodontopsis bardunovii (based on holotype). A, B & D. Single peristomes. C. Spore. Magnifications: A X 100, B X 440, C X 830, D x 2770.

polygonal or hexagonal shapes, mostly 60-70(90) µm long and 20-30 µm wide, about 2- 3.5 : I in I: w ratio, and at the base much longer and laxer, 150-200 µm long and 30-50 µm wide (3- 5 : I). Perigonial and perichaetial leaves not much different from the sterile leaves, infrequently becoming narrowly lanceolate. Paraphyses similar to axillary hairs, composed of 4- 5 elongate cells with a colored basal cell. Antheridia terminal on short lateral innovations, or in the axils of branch leaves, far fewer in number than the archegonia, about one perigonium per plant. Archegonia mostly found at the ends of stems and branches, but also scattered along the stem and branch axes, some with a stout basal stalk reaching half the archegonial length. Sporophytes common, mostly terminal, a few lateral, abundantly produced in early summer; setae pale brownish, to 4mm long, smooth. Capsules erect when dry, rarely bent, becoming horizontally oriented when moist owing to the twisting of the seta, subcylindric to pyriform, membranaceous, weakly sulcate when dry, slightly constricted below the rugulose mouth, about I mm long an 0.5 mm wide; exothecial cells oblong-rectangular, thin-walled, forming a band of 2- 3 rows of rounded to transversely rectangular cells near the mouth; stomata superficial, at neck region. Annulus not differentiated. Peristome single with no remnants of an exostome; 172 Joum. Hattori Bot. Lab. No. 71 I 9 9 2

,------Bryumr------ll Brachymenium

.._------Pohlia 1 1 ii'------ - L------~Sc:!:E.hizy~men~ium

Mielichhoferia

..------Orthodontium I L------orthodontopsis

Outgroup: Tayloria

FIG. I. Consensus cladogram showing the position of Orthodontopsis in relation to the other genera of the three subfamilies of Bryaceae. See text for more explanation.

endostome without basal membrance, segments up to 150 µm long and 20 µm wide, often reduced to much shorter processes, pale in color, smooth, perforated along the medial line, entire, cilia absent. Operculum with short and obtuse beak. Spores spherical, 15 to 20 µm in diameter, yellowish, papillose. Holotype: Altai Mts., Altai State Reserve, Karakem River basin, Ayulyuyuzyuk Creek, on rotten log, 20 Jun. 1989, M. Ignatov s.n. (MHA; isotype, FH, IRK). Paratype: Western Sayan Mts., upper range of Karasu River, on rotten log, 6 Jui. 1968, L. Bardunov s.n. (MHA, IRK) . To determine the subfamilial relationship of the new genus, Orthodontopsis, we ran the cladistic program (PAUP Version 2. 4. 1) using 9 characters taken from eight genera selected to represent the three subfamilies, with Tayloria as the outgroup. The resulting concensus cladogram is presented in Fig. 1. It is based on 18 equally parsimonious trees with a consistency index of 0.52. The characters selected and the polarity of character states analyzed in the cladogram will be discussed in separate paper under preparation. From Fig. 1, it appears that Orthodontopsis is most closely related to Orthodontium, and thus, belongs to the subfamily Orthodontioideae. It also shows that the subfamilial delimitation of Bryoideae and Mielichhoferioideae are both paraphyletic and would need realignment of the included genera.

ACKNOWLEDGMENTS We are grateful to Dr. Leonid V. Bardunov, the renowned Soviet bryologist who studies the of Southern Siberia, for placing his Western Sayan specimens of Orthodontopsis at our disposal. The specific epithet honors the man who first collected the species. Dr. Alexei K. Skvortsov kindly helped prepare the Latin diagnosis, Dr. Julia M. Plotnikova the SEM pictures and Dr. Nikolai I. Zolotukhin for arranging the field trip of the first author to the Altai region. Dr. H. Ochi kindly commented on the specimen and Dr. Z. Iwatsuki offered some good advices. Dr. D. Pfister helped edit the English text and Dr. B. Dutton assisted in running the initial PAUP program. The interpretation of the final consensus tree, however, is our responsibility. M. S. IGNATOV & B. C. TAN: Orthodontopsis, a new genus of Bryaceae 173

LITERATURE CITED Brotherus, V. F. 1924. Musci (Laubmoose). In Engler & Prantl (eds.), Die natiirlichen Pftiinzenfamilien, vol. 10. Leipzing. Chopra, R. N. & Sheel. 1974. Some new observations on the gametangia in Splachnaceae. Bryologist 77: 623- 628. Crum, H. A. & L. E. Anderson. 1981. Moses of Eastern North America, vol. I. Columbia University Press, New York. Fleischer, M. 1902- 1904. Die Musci der Flora von Buitenzorg, vol. 2. Leiden. Gangulee, H. C. 1974. Mosses of eastern India and adjacent regions, Fasc. 4. Funariales and . Calcutta. Koponen, A. 1981. Splachnobryaceae, a new moss family. Ann. Bot. Fennici 18: 123- 132. Koponen, T. & D. H. Norris. 1985. Bryophyte flora of the Huon Peninsula, Papua New Guinea. XL Brachymenium, Epipterygium , Leptobryum, Mielichhoferia , Orthodontium and Poh/ia (Bryaceae) and Leptostomataceae (Musci). Acta Bot. Fennica 131: 99- 127. Lawton, E. 1971. Moss Flora of the Pacific Northwest. Hattori Botanical Laboratory, Japan. Meijer, W. 1952. The genus Orthodontium. Acta Bot. Neerland. 1: 1- 80. Noguchi, A. 1988. Illustrated Moss Flora of Japan, Pt. 2. Hattori Botanical Laboratory, Japan. Nyholm, E. 1958. Illustrated Moss Flora of Fennoscandia, II. Musci, Fasc. 3. Lund. Ochi, H. 1959. A revision of the Bryaceae in Japan and the adjacent regions. Tottori University, Japan. Sainsbury, G. 0 . K. 1955. A handbook of the New Zealand mosses. Royal Soc. New Zealand Bull. 5: 1- 490. Shaw, J. 1985. Nomenclatural changes in the Bryaceae subfamily Mielichhoferioideae. Bryologist 88: 28- 30. --- & H. A. Crum. 1982. Comments on the Mielichhoferioideae of Central America with the description of a new species of Synthetodontium. Contr. Univ. Mich. Herb. 15: 209- 217. --- & ---. 1984. Peristome homology in Mie/ichhoferia and a taxonomic account of North American species. J. Hattori Bot. Lab. 57: 363- 381. ---& J. R. Rohrer. 1984. Endostomial architecture in diplolepideous mosses. J. Hattori Bot. Lab. 57: 41 - 61. Smith, A. J. E. 1978. The Moss Flora of Britain and Ireland. Cambridge University Press, England.