A Review of Taxithelium Subgenus Taxithelium (Bryophyta, Pylaisiadelphaceae) Author(s) :Paulo Eduardo A. S. Câmara Source: Systematic Botany, 36(4):824-835. 2011. Published By: The American Society of Plant Taxonomists URL: http://www.bioone.org/doi/full/10.1600/036364411X604840 BioOne (www.bioone.org) is a a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Systematic Botany (2011), 36(4): pp. 824–835 © Copyright 2011 by the American Society of Plant Taxonomists DOI 10.1600/036364411X604840 A Review of Taxithelium Subgenus Taxithelium (Bryophyta, Pylaisiadelphaceae) Paulo Eduardo A. S. Câmara Universidade de Brasília, Depto de Botânica. Campus Universitário Darcy Ribeiro, Asa Norte. Brasília, D. F. Brasil 70910-970. Missouri Botanical Garden, PO Box 299, Saint Louis, Missouri 63110, U. S. A. E-mail: pcamara@unb.br Communicating Editor: Jennifer Tate Abstract—Taxithelium, a moss genus traditionally associated with Sematophyllaceae and characterized by the presence of multiple papillae over the cell lumina, is revised with a worldwide perspective. Taxithelium subgenus Taxithelium comprises eight species. Endemic species include one each from Brazil, Africa, and South America, four from southeast Asia, and one species that occurs in both Africa and South America. Typifications, keys, descriptions, and illustrations are provided. Keywords—Bryophyta, pantropical, Pylaisiadelphaceae, Sematophyllaceae, Subgenus Taxithelium characters contrast to the filamentous pseudoparaphyllia and spreading lanceolate leaves found in subgenus Vernieri. Câmara and Kellogg (2010) have also shown variation in papillae shape and development between the two subgenera, with the so-called “baggy papillae” typical of subgenus Taxithelium, a possible synapomorphy for the group (Fig. 1). Subgenus Taxithelium is a particularly difficult group to study due to the variable and widespread taxon Taxithelium planum (Brid.) Mitt. The variable nature of this species has led to the description of many varieties and several new species. However after carefully examining as many as 6,200 specimens, I decided that those taxa represent one variable species and thus I adopt a wider concept of T. planum. In this paper, I present a taxonomic review of Taxithelium subgenus Taxithelium, completing a worldwide revision of the genus. Taxithelium Mitt. is a pantropical moss genus with 19 species found mostly between 30° N and 20° S, with most species occurring in southeast Asia, especially the Malesian region (Damanhuri and Longton 1996; Ramsay et al. 2002; Câmara 2011). Taxithelium was a member of the family Sematophyllaceae (Hypnales), but it lacks some typical “Sematophyllaceous” features, such as the absence of well developed alar cells, the lack of long rostrate opercula, and also the absence of collenchymatous exothecial cells (Seki 1969; Buck 1998). Consequently, Goffinet and Buck (2004) transferred Taxithelium to a newly described family Pylaisiadelphaceae; this familial placement was followed by Goffinet et al. (2009). As the relationship between these two families still remains unclear, I use the term Sematophyllaceae s. l. when needed to refer to the group Sematophyllaceae plus Pylaisiadelphaceae. The genus Taxithelium has been studied in a series of papers starting with Buck (1985), who revised the four Brazilian species. Various floristic studies have treated Taxithelium, e.g. Sharp et al. (1994) for Mexico, Buck (1998) for West Indies and Ramsay et al. (2002) for Australia. Câmara and Kellogg (2010) presented a detailed study of the morphology and development of Taxithelium papillae using scanning electron microscopy (SEM) and Câmara (2010) presented some new combinations for taxa formerly associated with Taxithelium. Câmara (2011) published a new circumscription of the genus to include two subgenera, Taxithelium (with eight species) and Vernieri (with 11 species). In that work (Câmara 2011), a complete taxonomic history and a detailed morphological study of the genus were presented, as well as a taxonomic review of subgenus Vernieri. A revision of subgenus Taxithelium has not previously been published and is presented in this paper. A phylogeny for the genus is also underway. The main character that traditionally defines Taxithelium is the presence of multiple papillae disposed in series on the lumina of leaf cells (hence, Tax- “taso” = arranged and thelion = nipple), a rare character within pleurocarpous mosses and even more rare among Hypnales. Câmara and Kellogg (2010) also have shown that some Taxithelium species have lost papillae during their evolution, but vestigial ones can be seen under SEM. This absence of papillae occurs only in two species, both in subgenus Taxithelium. Species within subgenus Taxithelium can be recognized by their complanate foliate stem and branches, oblong or ovate leaves, and the presence of foliose pseudoparaphyllia. These Materials and Methods Loans totaling 6,200 specimens have been obtained from 32 herbaria (B, BM, BR, CANB, DUKE, E, FH, G, H, INPA, JE, L, M, MG, MICH, MG, MO, NICH, NY, NSW, PC, PHS, S, SING, SINU, SP, TSN, UB, UFP, UPS, US, W). Specimens were re-hydrated in boiling water and then mounted in Hoyer’s solution (Anderson 1954). All observations and measurements were made from mounted material. Species are recognized on the basis of morphological characters, with support from molecular phylogenetic studies (Câmara and Shaw in prep.). Typifications are provided for all species and information from the protologue is presented when needed to clearly identify the type material and facilitate its location. When syntypes occurred, lectotypifications were done. For types not seen, new combinations, and excluded taxa see Câmara (2010, 2011). The morphological terms used are defined and illustrated in Magill (1990) and Gradstein et al. (2001). All measurements were made from leaves taken from the middle of the stem or branch. Specimens were mounted on a slide using Hoyer’s solution, and viewed under a Nikon Labophot-2 light microscope. Abbreviations of author’s names follow Brummitt and Powell (1992). Abbreviations of journals follow BPH (Lawrence et al. 1968). The selected specimens cited represent one plant per locality. Results Stem Anatomy—The stem anatomy shows no variation within the entire genus. The absence of a central strand is the only feature of taxonomic interest. Branching—Branching patterns show little or no intraspecific variation. Branches are mostly long creeping, prostrate to slightly-ascending, and forming flat mats. Branching 824 2011] Fig. 1. CAMARA: TAXITHELIUM 825 The typical “baggy” papillae present in subgenus Taxithelium and when such papillae form two rows (from Câmara and Kellogg 2010). patterns vary from irregular to subpinnate. The presence of foliose pseudoparaphyllia is constant and a diagnostic feature of the subgenus. Leaves—Leaves are not as variable as in subgenus Vernieri. Leaves in subgenus Taxithelium are always ovate and complanate varying only in size. A diagnostic feature of most species of subgenus Taxithelium is the presence of seriately arranged papillae over the lumina of the laminal cells. Two species lack leaf cell papillae under the light microscope, but in these cases vestigial papillae can be seen under SEM (Câmara and Kellogg 2010). Also according to Câmara and Kellogg (2010), the papillae are of the “baggy” kind and usually form one row, but it is not unusual to form two rows (Fig. 1). The only other Sematophyllaceous s. l. genus with pluripapillose leaf cells is Radulina W. R. Buck & B. C. Tan. This genus is easily distinguished from Taxithelium by the distally verrucose seta, collenchymatous exothecial cells, and inflated and colored alar cells. Phylogenetic studies also show that Radulina is not immediately related to Taxithelium (Tsubota et al. 2001). Costae are usually absent, but when present they are always double and short. This feature may vary within the same individual, although Taxithelium juruense (Broth.) Broth. appears to always have distinct short double costa, but unfortunately, the sampling for this taxon was poor (see taxonomy section). Alar cells are always present and differentiated, but usually not well developed, not inflated or colored. They resemble the alar region of some members of the Hypnaceae and usually consist of only one or two rows of cells. When occurring in several rows, they are still not inflated or colored. Exceptions are Taxithelium nepalense (Schwägr.) Broth., which has many upper quadratic alar cells and sometimes (rarely) colored ones, however it varies (even within the same individual). Taxithelium instratum (Brid.) Broth. and T. planum sometimes exhibit alar cells, even colored and slightly inflated, but again there is a significant amount of variation even within the same individual. On the other hand, the alar region is virtually absent in Taxithelium juruense. Representative variation can be seen in Fig. 2. The leaves do not vary considerably in shape. They are usually concave, or ovate to oblong. The margins can be entire or serrulate; the apex varies from acuminate to blunt (obtuse). Leaf size ranges from 0.55–1.65 mm long and 0.3–0.46 mm wide, but within a species there is much less variation. The branch and stem leaves usually do not differ in size, but when they do, the stem leaves are usually slightly larger than the branch ones. Leaf cells are usually linear (or long-linear), varying from 40–50 μm in length but with little variation in width (ca. 2– 3 μm wide). Measurements from mounted material were made from cell lumens. Perichaetia—The variation in perichaetial leaves is extensive. They can be oblong, lanceolate or ovate, with sizes ranging from 0.75–1.95 mm long and 0.17–0.45 mm across; the apex is usually distinct, acuminate, or setaceous. The margins can be entire or serrulate; and sometimes serrulate only near the apex. Costae are mostly absent, but when present, they are short and double. Both the laminal and apical cells are either pluripapillose, paucipapillose (poorly papilose), or smooth. There is little infraspecific variation in perichaetial features. Rhizoids—Rhizoids are usually yellowish to reddish; they can be either clustered or evenly distributed on the ventral surface of the stem. Sporophyte—Most sporophyte structures show little or no variation. Subgenus Taxithelium lacks a long-rostrate operculum, (this feature is present in some species in the subgenus Vernieri), and also lacks collenchymatous exothecial cells. The spores vary from 10–20 μm in diameter, smooth to lightly papillose. Fig. 2. Variation of alar region among the eight species of subgenus Taxithelium. Scale bars represent 100 μm. A. T. kerianum. B. T. instratum. C. T. leptosigmatum. D. T. homalophyllum. E. T. juruense. F. T. planum. G. T. concavum. H. T. nepalense. Intraspecific variation occurs but is not shown here. 826 SYSTEMATIC BOTANY Taxonomic Treatment Taxithelium Spruce ex Mitt., J. Linn. Soc., Bot. 12: 496. 1869. Hypnum Hedw. sect Omalia Müll. Hal. subsect. Sigmatella Müll. Hal., Syn. Musc. Frond 2: 263. 1851; Taxithelium Spruce, Cat. Musc. 14. 1867, nom. nud.; Hypnum sect. [Volume 36 Sigmatella (Müll. Hal.) Müll. Hal., J. Mus. Godeffroy 3(6): 86. 1874; Trichosteleum sect. Sigmatella (Müll. Hal.) A. Jaeger, Ber. Thätigk. St. Gall. Nat. Gess. 1876–77: 411. 1878; Sigmatella (Müll. Hal.) Müll. Hal., Bot. Jahrb Syst. 3: 328. 1896.—TYPE: Hypnum planum Brid., Musc. Recent. Suppl. 2: 97. 1812. Key to the Subgenera of TAXITHELIUM 1. Stem and branches complanate foliate with ovate to orbicular leaves; pseudoparaphyllia foliose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . subg. Taxithelium 1. Stems and branches spreading foliate with lanceolate leaves; pseudoparaphyllia filamentose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . subg. Vernieri Taxithelium subgenus Taxithelium—TYPE: Hypnum planum Brid., Musc. Recent. Suppl. 2: 97. 1812. Axes complanate, pseudoparaphyllia foliose, leaves ovate to orbicular. Plants small to medium-sized, forming flat mats. Stems long creeping, branching without order to subpinnate, short ascending or not; central strand absent; pseudoparaphyllia foliose, branches complanate. Stem and branch leaves usually similar, erect-spreading, broadly oblong-ovate, 0.55– 1.65 mm long × 0.2–0.60 mm wide; margins entire or serrulate; apex obtuse to blunt; costa absent or short and double; laminal cells linear, 40–50 μm long × 2–3 μm wide, seriately papillose over the lumina, sometimes smooth, never unipapillose, thin- or thick-walled; alar cells few, quadrate in basal angles, sometimes inflated and colored. Asexual propagula absent. Autoicous. Perigonia lateral; paraphyses present; antheridia 3–5; perigonial leaves lanceolate to oblong, concave; costae absent; laminal cells linear, lax, usually pluripapillose; alar cells not differentiated. Perichaetia lateral; paraphyses present; archegonia 3–5; perichaetial leaves lanceolate or ovate, 0.2–1.95 mm long × 0.17–0.45 mm wide; apex acuminate or aristate; costae absent or short and double; laminal cells linear, 24–95 μm long × ca. 2 μm wide, lax, pluripapillose or smooth; alar cells not or rarely differentiated. Setae elongate, slender, smooth, 0.8–2.0 cm long. Capsules inclined or erect, asymmetric, ovoid or cylindrical, constricted below mouth when deoperculate; 0.5–2.0 mm long; exothecial cells subquadrate, thick-walled, not collenchymatous; annulus not differentiated. Opercula short (rarely long), conic or obliquely conic-rostrate, ca. 0.3 mm long. Peristome double, hypnoid, exostome teeth narrowly triangular, with ziz-zag median line, cross-striolate below, papillose above, trabeculate at back; endostome with a high basal membrane, segments keeled, papillose, broad, perforate, as long as the teeth; cilia single, narrow, nodulose. Spores spherical, smooth or finely papillose, 10–20 μm in diameter. Calyptrae cucullate, naked, smooth. Key to the Species of TAXITHELIUM Subgenus TAXITHELIUM 1. Plants with smooth leaf cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Leaf cells thick-walled; perichaetial leaves 0.85–1.0 mm long; from southeast Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. T. leptosigmatum 2. Leaf cells thin-walled; perichaetial leaves 1.40–1.95 mm long; from Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. T. homalophyllum 1. Plants with pluripapillose leaf cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Perichaetial leaves smooth or paucipapillose at apex; from Brazil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. T. juruense 3. Perichaetial leaves pluripapillose; from Asia or Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Leaves 1.25–1.65 mm long, highly concave; from Northern South America . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. T. concavum 4. Leaves 0.5–1.2 mm long, slightly concave; from Asia, Africa or Southern South America . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Leaf margins entire at apex and below . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. T. kerianum 5. Leaf margins serrulate at apex or below . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6. Presence of many quadratic supra-alar cells; leaf apex obtuse or blunt acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. T. nepalense 6. Absence of many upper quadratic alar cells; leaf apex acute or long acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7. Leaf apex acuminate, margin strongly serrulate above; from southeast Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. T. instratum 7. Leaf apex acute, margin not or slightly serrulate; from the New World or Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. T. planum 1. Taxithelium concavum (Hook.) Spruce ex J. Florsch., Fl. Guianas, Series C, Bryophytes 1: 418. 1996. Hypnum concavum Hook., Syn. Pl. 2: 63. 1822.—TYPE: VENEZUELA. Rio Negro, San Carlos, Humboldt 34 (holotype: BM!). Sigmatella quelchii Müll. Hal., Malpighia 10: 519. 1896. Hypnum quelchii (Müll. Hal.) Paris, Index Bryol. 1898. Taxithelium quelchii (Müll. Hal.) Paris, Index Bryol. 1262. 1898.—TYPE: GUYANA. Georgetown, Marshall falls, J. Quelch s. n. (isotypes: BM!, M!, PC!, S!). Plants large, forming dull green or brown mats. Stems creeping, short–ascending, branched. Stem and branch leaves slightly differentiated; stem leaves larger and longer, erect- spreading, highly concave, 1.25–1.65 mm long × 0.20–0.25 mm wide, obovate or oblong, margins entire; apex slightly serrulate, acute or cuspidate; costae short and double or absent; laminal cells linear, 40–50 μm long × 2–3 μm wide, pluripapillose, thick-walled, basal cells sometimes smooth; alar cells poorly differentiated, consisting of 2 rows, supra alar cells many, not inflated, not colored. Rhizoids evenly distributed along the stem. Perichaetial leaves 1.65–1.85 mm long × 0.30– 0.40 mm wide, lanceolate, margins entire at base and slightly serrulate at apex; apex long-acuminate; costae absent; laminal cells linear, 50–65 × ca. 2 μm, thick-walled, pluripapillose at apex; alar cells poorly differentiated with 1 row, not inflated. Setae ca. 1.5 cm long. Capsules erect, asymmetric, ovoid, 2011] CAMARA: TAXITHELIUM 827 Fig. 3. A–D: Taxithelium concavum. A-B. Variation in leaf shape, C. Leaf margin cells, D. Alar region. E–H: Taxithelium instratum. E-F. Variation in leaf shape, G. Alar region, H. Leaf margin cells. A, B, E and F: scale a; D and G: scale b; C and H: scale c. 0.6–0.8 mm long, constricted below mouth; exothecial cells subquadrate, not collenchymatous. Opercula short, conic or obliquely conic-rostrate, ca. 0.3 mm long. Spores finely papillose, 15–20 μm across. Figures 3 A–D. Distribution and Habitat—Taxithelium concavum occurs from 80–300 m and is endemic to northern South America (Surinam, French Guiana, Guyana, and Venezuela; Fig. 4). Discussion—Taxithelium concavum is sometimes mistaken for T. planum, especially due to the variable morphology of the latter species. Buck (1985) has synonymized T. concavum with T. planum, however T. concavum can be differentiated by its larger size and the presence of non-inflated alar cells plus the presence of many upper alar cells. Leaf shape also differs in size, being much bigger in T. concavum. Representative Specimens Examined—FRENCH GUIANA. Saul, Tixier 13594 (PC). SURINAM. Sipaliwini, Allen 19187 (MO, NY); Corantijn River, Florschütz-de-Waard & Zielman 5730 (L, SP); Paramaribo, Price 396 (MO); Blanche Marie Falls, Allen 19294 (MO, SP). 2. Taxithelium instratum (Brid.) Broth., Rev. Bryol. 28: 110. 1901. Hypnum instratum Brid., Bryol. Univ. 2: 391. 1827.— TYPE: Patria ignota. Gaudichaud s. n. (isotypes: BM!, L!, NY!, PC!). Hypnum tenuisetum Sull. Proc. Amer. Acad. Arts 3: 78. 1854. Taxithelium tenuisetum (Sull.) Mitt., Fl. Vit. 397. 1873. Trichosteleum tenuisetum (Sull.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges.1876–77: 414, Sp. Musc. 2. 1878. Sigmatella tenuiseta (Sull.) Müll. Hal., Bot. Jahr. Syst. 23: 329. 1896.—TYPE: AMERICAN SAMOA. Island of Tutuila, sine legit (holotype: US! isotypes: BM!, PC!). Hypnum samoanum Mitt., J. Linn. Soc., Bot. 10: 184. 1868. Taxithelium samoanum (Mitt.) Mitt., Fl. Vit. 397. 1871. Trichosteleum samoanum (Mitt.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges 1876–77: 413, Sp. Musc. 2. Fig. 4. Distribution map for Taxithelium concavum (circles) and Taxithelium juruense (triangles). 1878.—TYPE: SAMOA. Upolu island, Powell 132 (holotype: NY!, isotypes: BM!, JE!, NY!). Hypnum capillipes Sande Lac., Bryol. Jav. 2: 188, 228. 287. 1868. Taxithelium capillipes (Sande Lac.) Broth., Nat. Pflanzenfam. I(3): 1091. 1908.—TYPE: INDONESIA. Java, Mount Salak, Blume s. n. (holotype: L!, isotypes: FH!, PC!). Taxithelium miokense M. Fleisch., Bot. Jahresber. 35(1): 276. 1908. nom. nud. Taxithelium binsteadii Broth. & Dixon, J. Bot. 53: 294. 540 f. 297. 1915.—TYPE: SRI-LANKA. Udapassellawa, Kirklees 413 (holotype: H!, isotypes: H!, NY!). Taxithelium papillisetum M. Fleisch., Musci Buitenzorg 4: 1340. 1923. Taxithelium instratum var. papillisetum (M. Fleisch.) Zanten, Nova Guinea, Bot. 10(16): 342. 1964.—TYPE: PAPUA NEW GUINEA. Moroka, Giussepe Loria s. n. (lectotype designated here: FH!, isolectotype: PC!) Taxithelium instratum var. kurzii Dixon, Bull. Torrey Bot. Club 51: 242. 1924.—TYPE: MYANMAR. Yonah, Kurz 2922 (holotype: BM!). Taxithelium batanense E. B. Bartram, Philipp. J. Sci. 68: 345. f. 444. 1939.—TYPE: PHILLIPINES. Batan, Mount Iraya, Bartlett 15471 (holotype: FH!, isotype: MICH!). Plants medium-sized, forming yellow-green mats. Stems creeping, short–ascending, branched. Stem and branch leaves same; erect-spreading, slightly concave, 0.85–1.10 mm long × 828 SYSTEMATIC BOTANY [Volume 36 MICH); Luzon, Ramos & Edaño B.S. 28938 (NY). SAMOA. Vaupel 130 (JE). SRI-LANKA. Udapassellawa, Binstead 413 (H). THAILAND. Pracinburi, Touw 12296 (NY), Phuket Island, Touw 11179 (NY), Nakhon Sawan, Touw 8346 (NY), Khao Chung Charoenphol et al. 3543 (NICH). VIETNAM. Tonkin: Laogai, Heinr 31 (H), Lam Dong, Tixier s. n. (PC). 3. Taxithelium juruense (Broth.) Broth., Natür. Pflanzenfam. I(3): 1090. 1908. Trichosteleum juruense Broth., Hedwigia 45: 285. 1906.—TYPE: BRAZIL. Acre. Rio Juruá -Mirim, Ule 2295 (holotype: H!). Fig. 5. Distribution map for Taxithelium instratum. 0.25–0.45 mm wide, ovate or lanceolate, margins entire below, strongly serrulate above; apex serrulate, acute or long acuminate; costae short and double or absent; laminal cells linear, 40–80 × 2–3 μm, pluripapillose, thick-walled, basal cells sometimes smooth; alar region small, alar cells few, oval, rarely slightly enlarged and colored, supra alar cells small, in triangular group, quadrate. Rhizoids clustered beneath the stem. Perichaetial leaves 1.20–1.90 mm long × 0.25–0.40 mm wide, lanceolate, margins entire at base and serrulate at apex; apex long-acuminate; costae absent; laminal cells linear, 50–65 × ca. 2 μm, thick-walled, strongly pluripapillose from midleaf above; alar cells poorly differentiated with 1 row, not inflated. Setae 1.5–2.0 cm long. Capsules erect, asymmetric, ovoid, 0.6–2.0 mm long, constricted below mouth; exothecial cells subquadrate, not collenchymatous. Opercula short, conic, or obliquely conic-rostrate, ca. 0.3 mm long. Spores 10–15 μm finely papillose. Figures 3E–H. Distribution and Habitat—Occurs on bark, tree trunks, and dead logs from sea level to 1,300 m in Malaysia, Borneo, Indonesia, Philippines, Myanmar, Papua New Guinea, Sri-Lanka, Samoa, Thailand, India, Australia, and Vietnam (Fig. 5). Discussion—This distinctive species can be easily recognized by the strongly serrulate acute or long-acuminate apex. The small alar region sometimes can be distinctive when it presents two essentially inflated and colored cells, but this not common. The papillation is strong even in the perichaetial leaves. Nomenclatural Notes—The protologue of Hypnum tenuisetum does not state who the collector was. All collections made during the Wilkes expedition lack collector information. However, Wilkes expedition material with matching protologue data was found in US and I am considering it the holotype. Representative Specimens Examined—AUSTRALIA. Queensland: Cape Tribulation, Streimann 45761 (NY), Rossville, Streimann 64593 (H). INDIA. Andaman Islands, Man 479 ( JE). INDONESIA. Java: Tijibodas Nyam s. n. (NY); Sumatra: Hoffmann 89–251 (NY), Bangka, sin. leg. (M), Seram, Akiyama 9534 (NY). MALAYSIA. Gombak, Câmara 957 (MO); Sabah, Poring, Câmara 1370 (MO); Sabah, Kinabalu Park Câmara 1047 (MO); Kuala Lumpur, Câmara 830 (MO); Johor, Ho 01–102 (SINU). PAPUA NEW GUINEA. East Sepik, Robbins 2426 (L); Moresby, Loria 1644 (NY), West Sepik, Koponen 34871 (NY), Morobe, Streimann 19770 (NICH). PHILIPINES. Mindanao, Zwickey 839 (MICH); Batan, Bartlett 15473 (FH, Plants large, forming dull-green mats. Stems creeping, short– ascending, branched. Stem and branch leaves slightly differentiated; stem leaves larger and longer, erect-spreading, slightly concave, 0.90–1.00 mm long × 0.25–0.35 mm wide, ovate or lanceolate, margins entire, slightly revolute; apex entire, acuminate; costae short and double or absent; laminal cells linear, 40–50 × 2–3 μm, pluripapillose, thick-walled, basal cells smooth; alar cells poorly differentiated, consisting of 2 rows, not inflated, not colored. Rhizoids evenly distributed along the stem. Perichaetial leaves 1.65–1.85 mm long × 0.30– 0.40 mm wide, lanceolate, margins entire at base and slightly serrulate at apex; apex long-acuminate; costae absent; laminal cells linear, 50–65 × ca. 2 μm, thick-walled, smooth or paucipapillose at apex; alar cells poorly differentiated with 1 row, not inflated. Setae ca. 0.8 cm long. Capsules erect, asymmetric, ovoid, 0.6–0.8 mm long, constricted below mouth; exothecial cells subquadrate, not collenchymatous. Opercula short, conic or obliquely conic-rostrate, ca. 0.3 mm long. Spores not seen. Figures 6F-I. Distribution and Habitat—Taxithelium juruense grows as an epiphyte on twigs in lowland Amazon forest and is only known from few collections. It is endemic to the state of Acre in Brazil and has not been collected since late 1970s (Fig. 4). Fig. 6. A–E: Taxithelium kerianum. A-C. Variation in leaf shape. D. Leaf margin cells. E. Alar region. F–I. Taxithelium juruense. F. Alar region, G. Leaf apex, H-I. Leaf shape variation. A, B, C, H and I: scale a; E and F: scale b; G and D: scale c. 2011] CAMARA: TAXITHELIUM 829 Discussion—This species is endemic to Brazil and is only known to occur in the state of Acre. It can be differentiated from T. planum by its mostly smooth perichaetial leaves, branch and stem leaves with revolute margins and the poorly developed alar region, which in some specimens is almost absent. Another useful character is the presence of papillae on the uppermost apex cells, which is usually smooth in T. planum. There were many collections mistakenly named as T. juruense in Brazilian herbaria, but they were mostly variations of T. planum or sometimes species of other genera, such as Hypnella. Câmara and Carvalho-Silva (2011) have studied this species in detail and provided its conservation status. Nomenclatural Notes—The protologue states that the collection was made in the state of Amazonas along the JuruáMyri river, however that river is actually within the state of Acre. Representative Specimens Examined—BRAZIL. Acre. Jurua-miry, Ule 2307 (H), Rio Moa, Prance 12541 (NY). 4. Taxithelium kerianum (Broth.) Broth., Natür. Pflanzenfam. I(3): 1091. 1908. Trichosteleum kerianum Broth., Oefvers. Förh. Finska Vetensk.-Soc. 33: 108. 1891.—TYPE: AUSTRALIA. Queensland, Harvey’s Creek, F. M. Bailey 598 (holotype: H). Taxithelium sublaevifolium Broth. & Paris, Rev. Bryol. 27: 79. 1900.—TYPE: VIETNAM, Tonkim, between Ba-Hoa et Pho-Lu, close to La-Kay, Moutier s. n. (holotype: H!, isotype: PC!). Taxithelium hirtellum Paris & Renauld, Rev. Bryol. 29: 80. 1902.—TYPE: MADAGASCAR, sine legit. (holotype: PC!, isotypes: BR!, FH!, H!, PC!). Plants small, forming pale golden-green mats. Stems creeping, short–ascending, branched. Stem and branch leaves same; not spreading, slightly concave, 0.85–1.10 mm long × 0.25–0.45 mm wide, ovate or lanceolate, margins entire, involute; apex entire, acute or long acuminate; costae short and double or absent; laminal cells linear, 40–80 × 2–3 μm, pluripapillose, thick-walled, basal cells sometimes smooth; alar region small, alar cells few, oval, sometimes slightly enlarged at angles, not colored, supra alar cells small, in 2–3 rows, quadrate. Rhizoids clustered beneath the stem. Perichaetial leaves 1.30–1.70 mm long × 0.20–0.30 mm wide, lanceolate, margins entire at base and serrulate at apex; apex longacuminate; costae absent; laminal cells linear, 50–65 × ca. 2 μm, thick-walled, pluripapillose at apex; alar cells poorly differentiated with 1 row, not inflated. Setae 0.5–1.0 cm long. Capsules inclined, asymmetric, ovoid, 0.8–1.5 mm long, constricted below mouth; exothecial cells subquadrate, not collenchymatous. Opercula short, conic, or obliquely conicrostrate, ca. 0.3 mm long. Spores 15–20 μm finely papillose. Figures 6A–E. Distribution and Habitat—Taxithelium kerianum occurs on bark, twigs, and small logs mostly from lowland forests in Indonesia, Borneo, Malaysia, Guam, Phillipines, Papua New Guinea, Madagascar, Australia, and Indochine (Fig. 7). Discussion—This species can be differentiated from T. instratum by the entire margins and the somewhat enlarged non-colored alar cells. Specimens from Madagascar are different in that the apex is much shorter and the alar cells are sometimes colored. As all other characters match T. kerianum, I am considering those characters as natural variation within the species. Fig. 7. Distribution map for Taxithelium kerianum. Nomenclatural Notes—It was not possible to locate the type specimen of T. kerianum. According to Ramsay et al. (2002), the holotype is at H (as expected) and an isotype exists at BRI. Unfortunately it was not possible to obtain a loan from BRI and even visiting H personally, I was not able to find the type. However, based on the original description, as well as the descriptions and illustrations provided by Gangulee (1980) and Ramsay et al. (2002), I believe that this will be the correct name of the species. There is no data on the type collector of Taxithelium hirtellum, although the protologue information states that the collection was made by Sakalave soldiers. It is known that Paris, as a general, had soldiers collecting for him. Representative Specimens Examined—AUSTRALIA. Queensland, Streimann 45764 (NY). GUAM. sin. leg. (MICH). INDONESIA. Bali, Touw & Snoek 24745 (L), Seram, Akiyama 16037 (NY). MADAGASCAR. Toamasina, Petiot 2–3/345 (MO); Maintirano, sin. leg. (PC). MALAYSIA. Selangor, Câmara 786 (MO); Johor, Ho 1–95 (SINU); Sabah, Kinabalu Park, Câmara 1194 (MO). PAPUA NEW GUINEA. sin. loc. Nyman s. n. (UPS). PHILLIPINES. Tan 89–1425 (FH). 5. Taxithelium leptosigmatum (Müll. Hal. ex Geh.) Paris, Rev. Bryol. 28: 111. 1901. Trichosteleum leptosigmatum Müll. Hal. ex Geh. Biblioth. Bot. 44: 24. 20. 1898.—TYPE: PAPUA NEW GUINEA. Soron 156 (isotypes: FH!, L!). Taxithelium merrillii Broth., Philipp. J. Sci. 13: 219. 1918.—TYPE: PHILLIPINES. Palawan, Taytay, Merrill 8992 (holotype: H!, isotypes: FH!, H!, L!, NY!, PC!, US!). Taxithelium subtrachaelophyllum Dixon, Bull. Torrey Bot. Club 51: 243. f.3: 18. 1924.—TYPE: SINGAPORE, Ridley 695 (lectotype designated here: BM!). Taxithelium dimorphophyllum Dixon & Herzog, Hedwigia 66: 353. 50–53. 1926.—TYPE: MALAYSIA. Sabah, Tandjoeng Redet, R. Wegner s. n. (holotype: BM!, isotype: JE!). Taxithelium novae-guineae Dixon, Farlowia 1: 39. 1943.—TYPE: PAPUA NEW GUINEA. Kanosia, Carr 11470 (holotype: BM!, isotypes: BR!, CANB!, DUKE!, FH!, H!, JE!, L!, M!, MICH!, NICH!, PC!, S!, SING!, US!, W!,). Plants large, forming brown-dark mats. Stems creeping, long–ascending, branched. Stem and branch leaves slightly differentiated; stem leaves larger and longer, erect-spreading, slightly concave, 0.75–0.95 mm long × 0.30–0.40 mm wide, 830 SYSTEMATIC BOTANY oblong-lanceolate, margins entire; apex entire, obtuse to acute; costae short and double or absent; laminal cells linear, 40–50 × 2–3 μm, smooth, thick-walled, basal cells smooth; alar cells poorly differentiated, consisting of a single basal row and a triangular group of few supra alar cells, not inflated. Rhizoids evenly distributed along the stem. Perichaetial leaves 0.85– 1.0 mm long × 0.20–0.30 mm wide, oblong to linear, margins entire; apex obtuse; costae absent; laminal cells linear, 50–65 × ca. 2 μm, thick-walled, smooth; alar cells poorly differentiated with 1 row, not inflated. Setae up to 1.7 cm long. Capsules erect, asymmetric, ovoid, 0.6–0.8 mm long, constricted below mouth; exothecial cells subquadrate, not collenchymatous. Opercula short, conic or obliquely conic-rostrate, ca. 0.3 mm long. Spores finely papillose, 15–20 μm across. Figures 8A–D. Distribution and Habitat—Taxithelium leptosigmatum occurs mostly on lowlands, on silty sediments, and sometimes on exposed mangrove roots in Singapore, Borneo, Papua New Guinea, Philippines, and Australia (Fig. 9). Discussion—For many years the genus Taxithelium has been recognized by the presence of pluripapillose cells, therefore specimens lacking this feature have been mostly ignored were not considered as Taxithelium. However, Câmara and Kellogg (2010) have shown that representatives of Taxithelium that lack papillae do retain some traces of them, which are only visible using SEM. Our molecular study has also shown that these plants do belong to the genus and that the papillae have been lost during evolution (Câmara and Kellogg 2010). This species is easily recognized by its dark-brown color and the absence of papillae in almost every specimen; however, some T. leptosigmatum from Australia may have faintly visible papillae over the lumina of leaf cells and have been called T. merrilli. Fig. 9. [Volume 36 Distribution map for Taxithelium leptosigmatum. Nomenclatural Notes—It was not possible to locate the holotype of T. leptosigmatum, it was probably lost during the bombing of Berlin herbarium in 1943. Representative Specimens Examined—AUSTRALIA. Queensland, Streimann 64500 (S). BRUNEI. Tutong Town, Tan 95–1312 (NICH). MALAYSIA. Sabah, Ridley 695 (BM). PAPUA NEW GUINEA. Morobe, Bellamy 186 (TNS). PHILLIPINES. Samar Island, Gruezo 8235 (TNS). SINGAPORE. Bukit Timah, Ridley 692 (BM, SING). 6. Taxithelium nepalense (Schwägr.) Broth., Monsunia 1: 51. 1899. Hypnum nepalense Schwägr., Sp. Musc. Frond., Suppl. 3. 1(2): 226. 1828. Stereodon nepalensis (Schwägr.) Mitt., J. Proc. Linn. Soc., Bot., Suppl. 2: 100. 1859. Trichosteleum nepalense (Schwägr.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges 1876–77: 412. Sp. Musc. 2. 1878.—TYPE: NEPAL. Hooker s. n. (holotype: G!, isotypes: BM!, G!). Hypnum polystictum Mitt., Hand. N. Zeal. Fl. 482. 1867. Taxithelium polystictum (Mitt.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges 1876–77: 423 (Gen. Sp. Musc. 2: 489). 1878.—TYPE: NEW ZEALAND. Northern Island, Knight s. n. (holotype: NY!). Hypnum gottscheanum Hampe ex Müll. Hal., Linnaea 38: 568. 1874. Taxithelium gottscheanum (Hampe ex Müll. Hal.) Broth., Nat. Pflanzenfam. I(3): 1091. 1908.—TYPE: PHILIPPINES. Bajosan, Dr. C. Semper 24, (holotype: BM!, isotypes: FH!, H!). Taxithelium glaucophyllum Besch. Ann. Sci. Nat.; Bot., sér. 6, 10: 310. 1880.—TYPE: MADAGASCAR. Nossi-Bé, Marie s. n. (lectotype designated here: BM!, isolectotype: PC!). Taxithelium planulum Besch., Ann. Sci. Nat.; Bot., sér. 6, 10: 309. 1880.—TYPE: MADAGASCAR. Nossi-Bé, Loucoubé, Marie s. n. (holotype: BM!, isotypes: H!, NY!, PC!, S!). Fig. 8. A–D: Taxithelium leptosigmatum. A-B. Variation in leaf shape. C. Leaf margin cells. D. Alar region. E–H: Taxithelium nepalense. E-F. Variation in leaf shape. G. Alar region. H. Leaf margin cells. A, B, E and F: scale a; D and G: scale b; C and H: scale c. Hypnum selenithecium Müll. Hal., Bot. Jahr. Syst. 5: 86. 1883. Taxithelium selenithecium (Müll. Hal.) Paris, Nat. Pflanzenfam. I(3): 1091. 1908. Trichosteleum selenithecium (Müll. Hal.) Kindb., Enum. Bryin. Exot., suppl. 2. 1891.— TYPE: SAMOA. H. Powell s. n. (isotypes: BM!, JE!). Hypnum turgidellum Müll. Hal., Bot. Jahr. Syst. 5: 87. 1883. Taxithelium turgidellum (Müll. Hal.) Paris, Index Bryol. 2011] CAMARA: TAXITHELIUM 831 (ed. 2) 4: 358. 1905.—TYPE: INDONESIA. Ambon island, Naumann s. n. (isotypes: BM!, JE!). Hypnum tabescens Müll. Hal., Biblioth. Bot. 13: 7. 1889. Taxithelium tabescens (Müll. Hal.) Kindb., Rev. Bryol. 28: 111. 1901.—TYPE: PAPUA NEW GUINEA. Fly River, W. Bäuerlen 58a (lectotype designated here: BM!). Taxithelium laetum Renauld & Cardot, Bull. Soc. Bot. Belgique 31(2): 110. 1892. Trichosteleum laetum (Renauld & Cardot) Paris, Index Bryol. 1312. 1898.—TYPE: MADAGASCAR. Analamazoatra, Camboué et Campenon s. n. (holotype: PC?, isotype: S!). Trichosteleum diaphanum Broth., Oefvers. Förh. Finska VetenskSoc. 37: 171. 1895. Taxithelium diaphanum (Broth.) Broth., Nat. Pflanzenfam. I(3): 1091. 1908.—TYPE: PAPUA NEW GUINEA. New Ireland, W. Micholitz s. n. (holotype: H!). Taxithelium nanangium Paris, Index Bryol. 1261. 1898. nom. nud. Taxithelium percapillipes Broth., Philipp. J. Sci. 8: 89. 1913.— TYPE: PHILLIPINES. Polillo, Bar. Sci. 6885 Robinson (holotype: H!, isotypes: BM!, E!, NY!, S!, US!). Taxithelium trachaelophyllum Dixon, Bull. Torrey Bot. Club 51: 243. f. 3: 17. 1924.—TYPE: MYANMAR. Yonah, Kurz 3332 (holotype: BM!, isotypes: G!, NY!, S!). Plants large, forming yellow-green mats. Stems creeping, short–ascending, branched. Stem and branch leaves slightly differentiated; stem leaves larger and longer, erect-spreading, slightly concave, 0.75–1.15 mm long × 0.22–0.42 mm wide, ovate or lanceolate, margins entire below, serrulate above; apex serrulate, obtuse or blunt acute; costae short and double or absent; laminal cells linear, 40–80 × 2–3 μm, pluripapillose, thick-walled, basal cells smooth; alar cells several, small, rectangular to oval, not inflated, supra alar cells many, quadrate. Rhizoids clustered beneath the stem. Perichaetial leaves 0.70–1.75 mm long × 0.25–0.40 mm wide, lanceolate, margins entire at base and slightly serrulate at apex; apex long-acuminate; costae absent; laminal cells linear, 50–65 × ca. 2 μm, thick-walled, pluripapillose at apex; alar cells poorly differentiated with 1 row, not inflated. Setae 0.8–1.5 cm long. Capsules inclined, asymmetric, ovoid, 0.6–2.0 mm long, constricted below mouth; exothecial cells subquadrate, not collenchymatous. Opercula short, conic or obliquely conicrostrate, ca. 0.3 mm long. Spores 15–20 μm finely papillose. Figures 8 E–H. Distribution and Habitat—Taxithelium nepalense grows on tree trunks, bark (trees?), dead logs, exposed roots, and rocks, from sea level to 1,000 m in Nepal, Singapore, Indonesia, Malaysia, Borneo, Papua New Guinea, Nepal, Thailand, Myanmar, Australia, Sri-Lanka, Madagascar, China, Comoros, New Zealand, India, Buthan, and Laos (Fig. 10). Discussion—Taxithelium nepalense is the most common and widespread Taxithelium in Asia. It has been synonymized with T. planum by Buck (1998), however both can be differentiated by the alar region, which in T. nepalense is not inflated or enlarged and has many upper quadratic alar cells. Another difference is that T. nepalense has serrulate margins only at the apex, while T. planum normally has serrulate margins below the apex. The Chinese specimens are somewhat different in having a longer acuminate apex, resembling T. instratum, but the alar Fig. 10. Distribution map for Taxithelium nepalense. cells are clearly those of T. nepalense. This may represent a new species, however, taking into consideration that T. nepalense is a variable species, it seems more appropriate to recognize it as a synonym. Representative Specimens Examined—AUSTRALIA. Queensland, Streimann 57566 (CANB), Cape Tribulation, Streimann 45758 (NY), Cooktown, Streimann 56999 (NY); Northern Territory, Greenant Creek, Streimann 48570 (MO), Melville Island, Russel-Smith 5728 (NY), Kadacu National Park, Streimann 39551 (NY), Pathericks rainforest, Streimann 48165 (NY). BUTHAN. sin. loc. Griffith 592 (PC). CHINA. Guandong province, Redfearn 34370 (MO, NY). COMOROS. Mayotte, Magill & Pócs 11602 (MO, NY). INDIA. Calcutta, Griffith s. n. (M), Assam, Marlen 5647 (PC). INDONESIA. Java, Bogor, Fleisher 336 (NY), Ambon Island, Robinson 2311 (NY), West Seram, Akiyama 15689 (NY). LAOS. Vientiane, Tixier s. n. (PC). MADAGASCAR. sin. loc. Marie J. s. n. (NY), Nosy Be, Marie 12 (PC), Tananarive, Cremers 21188 (PC). MALAYSIA. Gombak, Câmara 958 (MO), Penang, Moller s. n. (NY); Sabah, Poring, Câmara 1388 (MO). MYANMAR. Rangoon, Dickason 8667 (H). NEPAL. sin. loc. Wallich s. n. (H). PAPUA NEW GUINEA. West Sepik, Koponen 34837 (MO); East Sepik, Robbins 2477 (L). PHILLIPINES. Luzon, Merril 3543 (NY); Laguna, Brown 17928 (NY); Lumbucan island, Merrill 7193 (NY), Panay, Martelino & Edano B. S. 35804 (H). SINGAPORE. Câmara 1411 (MO).SRI-LANKA. Hiniduma, Herzog 7 (JE). THAILAND. Kao Chong, Charoenphol et al. 3532 (MO). 7. Taxithelium planum (Brid.) Mitt., J. Linn. Soc., Bot. 12: 496. 1869. Hypnum planum Brid., Muscol. Recent. Suppl. 2: 97. 1812. Stereodon planus (Brid.) Mitt., J. Proc. Linn. Soc. 7: 157. 1863. Sigmatella plana (Brid.) Müll. Hal., Hedwigia 37: 259. 1898.—TYPE: HISPANIOLA. Poiteau s. n. (holotype: B!). Hypnum acuminulatum Hornsch., Fl. Bras. 1(2): 76. 1840. Taxithelium planum var. acuminulatum (Hornsch.) Paris, Index Bryol. 1262. 1898.—TYPE: BRAZIL. Teffe, sine legit (isotype: BM!). Hypnum octodiceroides Müll. Hal., Linnaea 39: 463. 1875. Taxithelium octodiceroides (Müll. Hal.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1876–77: 423 (Gen. Sp. Musc. 2: 489). 1878.—TYPE: CAMEROON. Mbanga, Schweinfurthi s. n. (isotypes: H!, JE!, S!, W!). Taxithelium planum var. distichum Besch., Ann. Sci. Nat. Bot., sér. 6, 3: 256. 1876.—TYPE: MARTINIQUE. Husnot 180 (isotypes: H!, M!). Hypnum afroacuminulatum Müll. Hal., Bot. Jahr. Syst. 5: 88. 1883. Taxithelium afroacuminulatum (Müll. Hal.) Paris, 832 SYSTEMATIC BOTANY Index Bryol. 1260. 1898.—TYPE: CAMEROON. Mungo. Naumann s. n. (isotypes: BM!, E!, FH!). Hypnum chloropterum Müll. Hal., Flora 69: 522. 1886. Brachythecium chloropterum (Müll. Hal.) Paris, Index Bryol. Suppl. 1. 1900. Trichosteleum chloropterum (Müll. Hal.) Kindb., Enum. Bryin. Exotic. suppl. 2. 1891. Taxithelium chloropterum (Müll. Hal.) Renauld & Cardot, Rev. Bryol. 28: 110. 1901.—TYPE: EQUATORIAL GUINEA. Bioko, W. Mönkemeyer s. n. (isotypes: BR!, H!, JE!, PC!). Hypnum kuilui Müll. Hal., Flora 69: 523. 1886. Trichosteleum kuilui (Müll. Hal.) Kindb., Enum. Bryin. Exotic. suppl. 2. 1891. Taxithelium kuilui (Müll. Hal.) Renauld & Cardot, Rev. Bryol. 28: 111. 1901.—TYPE: EQUATORIAL GUINEA. River Kuilui, Dr. Pechuel –Losche s. n. (isotype: H!). Taxithelium leptopunctatum Broth., Bot. Jahr. Syst. 24: 266. 1897.—TYPE: LIBERIA. Monrovia, Dusén s. n. (holotype: H!, isotypes: BR!, PC!, S!). Taxithelium rotundatulum Broth., Bot. Jahr. Syst. 24: 265. 1897.— TYPE: CAMEROON. N’Dian, Dusén 703 (holotype: H!, isotypes: BM!, DUKE!, JE!, M!, NY!, PC!, S!, UPS!). Sigmatella pseudo-acuminulata Müll. Hal., Bull. Herb. Boissier 5: 214. 1897. Taxithelium pseudo-acuminulatum (Müll. Hal.) Paris, Index Bryol. 1897. Taxithelium pseudo-acuminulatum (Müll. Hal.) Paris, Rev. Bryol. 28: 111. 1901. Hypnum pseudoacuminulatum (Müll. Hal.) Paris, Rev. Bryol. 28: 111. 1901.—TYPE: GUATEMALA. Mazatenago, Bernoulli et Cario 87 (lectotype designated here: PC!, isolectotype: W!). Taxithelium planum var. subjulaceum Besch., Index Bryol. Suppl. 1. 317. 1900. nom. nud. [Volume 36 0.55–1.2 mm long × 0.30–0.60 mm wide, ovate or oblong lanceolate, sometimes obovate, margins not or slightly serrulate; apex serrulate, acute; costae short and double or absent; laminal cells linear, 40–50 × 2–3 μm, pluripapillose, thin-walled, basal cells smooth; alar cells 2–4, large, sometimes with many supra alar cells, sometimes inflated, colored or not. Rhizoids evenly distributed along the stem. Perichaetial leaves 0.85– 1.40 mm long × 0.20–0.30 mm wide, lanceolate, margins serrulate at apex; apex acuminate or aristate; costae absent; laminal cells linear, 50–65 × ca. 2 μm, thick-walled, pluripapillose; alar cells poorly differentiated with 1 row, not inflated. Setae 0.8–2 cm long. Capsules erect, asymmetric, ovoid, ca. 0.8 mm long, constricted below mouth; exothecial cells subquadrate, not collenchymatous. Opercula short, conic or obliquely conicrostrate, ca. 0.3 mm long. Spores finely papillose, 10–15 μm across. Figures 11E–K. Distribution and Habitat—Taxithelium planum is the most widespread species of the genus, occurring in most habitats, usually on tree trunks and dead logs between sea level and 1,165 m from Florida, Central and South America, and West Tropical Africa (Fig. 12). Discussion—Taxithelium planum is probably one of the most common and widespread moss species in the Neotropics. Probably more than 90% of herbarium specimens filed under Taxithelium belong to T. planum. Its morphology is variable and has led to the description of many new species and varieties. Buck (1998) has suggested that those forms are most likely due to ecological constraints. A careful study of many specimens have convinced me that T. planum presents a continuum of variation and I find no support for many varieties and forms, as well as many species, which reflect only a highly variable taxon. Therefore I adopt here a broad concept of T. planum encompassing a large range of variation. Sigmatella olida Müll. Hal., Hedwigia 40: 69. 1901. Taxithelium olidum (Müll. Hal.) Renauld & Cardot, Rev. Bryol. 28: 110. 1901.—TYPE: BRAZIL. Rio de Janeiro, Morro de Dois Irmãos, E. Ule 1723 (isotype: NY!). Taxithelium laxiusculum Renauld & Cardot, Rev. Bryol. 28: 110. 1901. nom. nud. Taxithelium guineense Broth. & Paris, Rev. Bryol. 31: 49. 1904.— TYPE: GUINEA. Kourousa, Pobeguin s. n. (holotype: H!, isotypes: FH!, H!, M!, PC!). Taxithelium subrotundatulum Broth. & Paris, Rev. Bryol. 31: 121. 1904.—TYPE: GUINEA. Kourousa, Pobeguin s.n (holotype: H!, isotypes: H!, L!, M!, PC!, S!). Taxithelium glaucovirens Cardot, Rev. Bryol. 36: 50. 1909.— TYPE: CENTRAL AFRICAN REPUBLIC. Ubangi, Laurent s. n. (holotype: PC!, isotypes: H!, PC!) Taxithelium planum var. teretiusculum Renauld & Cardot, Rev. Bryol. 38: 42. 1911.—TYPE: GUATEMALA. Watson s. n. (isotype: S!). Taxithelium rotundatulum var. minus Broth. ex Corb., Fl. Afr. Centr. Énum. Pl. Récolt. 1902–1904: 394. 1913.—TYPE: CENTRAL AFRICAN REPUBLIC. Ubangi, Desbordersville s. n. (isotypes: PC!, S!). Plants medium- to large-sized, forming green-yellow mats. Stems long-creeping, long–ascending, branched. Stem and branch leaves similar, erect-spreading, slightly concave, Fig. 11. A–D: Taxithelium homalophyllum. A-B. Variation in leaf shape. C. Leaf margin cells. D. Alar region. E–K: Taxithelium planum. E. Alar region. F. Leaf margin cells. G–K. Variation in leaf shape. A, B and G–K: scale a; D and E: scale b; C and F: scale c. 2011] Fig. 12. CAMARA: TAXITHELIUM Distribution map for Taxithelium planum. This point of view finds support also on investigations using molecular tools (Câmara and Shaw in prep.). Taxithelium planum has also been confused with T. nepalense, another variable species from southeastern Asia. Buck (1998) synonymized the two species, however I consider them to be distinct. Nomenclatural Notes—It was not possible to locate the holotypes for the following names: Sigmatella olida, Hypnum afroacuminulatum, Hypnum octodiceroides, Hypnum chloropterum, Hypnum kuilui, and Sigmatella olida, all Müller Hallensis names nad the type is was likely lost during the bombing of Berlin herbarium in 1943. Representative Specimens Examined—ANTIGUA AND BARBUDA. Antigua, Rose 3675 (NY). BAHAMAS. New Providence. Britton 68 (NY). BARBADOS. St. Joseph, Welch 21100 (NY). BELIZE. Cayo, Balick 2425 (NY), Toledo, Whittemore 6463 (MO). BOLIVIA. Beni, Marko Lewis 89–024 (MO); Cochabamba, Churchill et al. 19864-B (MO), Lewis 83–1363 (NY); La Paz, Fuentes 4404 (MO); Madidi, Fuentes 5472 (NY, MO); Pando, Catari et al. 290 (MO); Santa Cruz, Churchill et al. 21541 (MO). BRAZIL. Alagoas Murici, Porto s. n. (UFP); Amapá, Rio Jari, Egler & Irwin 46454 (NY); Acre, Brasileia, Lowy BBr 524 (MO); Amazonas, Rio Pitinga, Buck 3206 (MO), Tefé sin. leg. (BM), São Gabriel da Cachoeira, Buck 2582 (NY), Serra da Neblina at base camp, Maguire et al. 60218 (NY), Rio Uatumã, Buck 3036 (NY), Manaus, Ule 2332 (H); Bahia, Ilhéus, Messias & Oliveira 25 (NY); Distrito Federal: Área de Proteção Ambiental de Cafuringa, dolina da Garapa, sobre tronco vivo, Soares & Oliveira 136 (UB); Goiás, Apore, Silva 64 (MO), São João da Alianca, Irwin et al. 31992 (NY); Mato Grosso, Alto Garça, Silva 642 (MO), Cuiabá, Irwin s. n. (UB), Cáceres, Hoehne 481 (JE); Minas Gerais, Uberaba, Ule 1598 (H). Pará, Acará, Mexia 6944 (MO), Ilha de Marajó, Sobel et al. 4911A (NY), Serra Cachimbo, Reese 16140 (MO); Pernambuco, Cabo de Santo Agostinho, Guedes M. 05 (UFP), Caruaru, Porto 63 (UFP), Recife, Porto & Yano s. n. (UFP); Rondonia, Mibrasa, McFarland et al. 187 (MO); Roraima, Bonfim, Santiago 043 (UFP), Rio Uraricoera, Pires et al. 16750 (NY), Rio Surumu, Buck 2033 (MO); São Paulo, Bertioga, Schiffner 665 (H), Ilha do Cardoso, Vital 6849 (MO). CAMEROON. Fako, Thompson 1394 (NY). COLOMBIA. Amazonas, Churchill 16147 (NY); Antioquia, Churchill 17082 (NY); Chocó, Churchill 18604 (MO); Guainia, Churchill 17619 (MO); Nariño, Ramirez 9813 (MO); Vaupes, Schultes & Cabrera 11943 (MO). CONGO. Brazzaville, Lt. Jeannelle 4838 (PC). COSTA RICA. Cocos Island, Gómez 4612 (NY), Guanacaste, Rodriguez 304 (MO), Limon, Daly 98 (MO); Puntarenas, Crosby 3829 (MO); San Jose, Skutch 2843 (MO). CUBA. Pinar del Rio, Britton et al. 13975 (MO); Santiago de Cuba, Pócs & Reyes 9044/E (MO). DOMINICA. Sin. loc. Hegewald 9308 (MO). DOMINICAN REPUBLIC: Duarte, Zanoni 16114 (MO); El Seibo, Zanoni 12022 (MO); La Altagracia, Reese 15562 (MO); La Vega, Zanoni 30945 (MO); Samana, Smith 10411 (MO); San Cristobal, Mejía & Zanoni 9654 (MO); Sanchez Ramirez, Zanoni & Peláez 16175 (MO). ECUADOR. Los Rios, Dodson 5814b (MO); Morona-Santiago, Ortega 506 (MO); Napo, Mexia 7072a (MO); Pastaza, Mexia 6901a (MO); Sucumbios, Heikkinen RH 1990–313 (MO); Zamora- 833 Chinchipe, Churchill et al. 24243 (MO). EQUATORIAL GUINEA. Cogo, Patxi Heras 1004/93 (MO). FRENCH GUIANA. Cayenne, Buck 38014 (NY). GABON. Douya-Onoy, Magill & Crosby 8621 (NY). GRENADA. Belle Vue. Broadway s. n. (NY). GUADALOUPE. Sloover 23523 (MO). GUATEMALA. Alta Verapaz, Croat 41615 (MO), Mazatenago, Bernoulli & Cario 87 (PC). GUYANA. Mazaruni. Graham 99 (MO). HAITI. Sin. loc. Bartlett 17570 (MO). HONDURAS. Colón, Saunders 829 (MO). IVORY COAST. Tai National Park, Porembsri 381 (NY). JAMAICA. Manchester, Crosby 13849 (MO); Portland, Crosby 13738 (MO); St. James, Crosby 13958 (MO); St. Mary, Orcutt 4261 (MO); St. Thomas, Crosby 2956 (MO). MARTINIQUE. Stehlé 3828 (NY). MEXICO. Campeche, Cárdenas 1001b (NY); Oaxaca, San Pedro de Tepinapa, Santos 3409 (NY); Puebla, Santos 3652 (NY); Veracruz de Ignacio de la Llave. Delgadillo s. n. (NY). MONTSERRAT. Mt. Gages, Shafer 824 (NY). NETHERLANDS ANTILLES. Saint Eustatius, Wiersma et al. 263M (NY); Saint Maarten, Pic du Paradis, Buck 25908 (NY). NICARAGUA. Zelaya, Stevens 12934 (MO). PANAMA. Bocas del Toro, Allen 5539 (MO); Canal Area, Crosby 3939 (MO); Chiriqui, D’Arcy 6489 (MO); Colón, Crosby 10302 (MO); Darien, Allen 8750 (MO); Panamá, Crosby 4548B (MO). PERU. Ayacucho, Timme 12272 (MO); Huanuco, Hegewald 8303 (MO); Loreto, Mexia 6474 (MO); Madre de Dios, Majestyk 4208 (MO). PUERTO RICO. Crosby 2078 (MO). ST. LUCIA. Hegewald 9595 (MO). SAINT KITTS AND NEVIS. St. Thomas Middle Island Parish, Buck 29487 (NY). ST. VINCENT AND THE GRENADINES: St. Vincent. Parker s. n. (NY). SURINAM. Brokopondo, Allen 19333 (MO); Para, Magombo 5406 (MO); Sipaliwini, Allen 25506 (MO); Wanica, Magombo 5001 (MO). TOBAGO. Charlotteville, O’Shea 01P02 (NY). TRINIDAD. Crosby 2078 (MO). U. S. A. Florida: Dade Co., Brickell Hammock, near Miami, Small 3224 (NY); Small 5138 (NY); Collier Co., Skull 107 (NY); Everglades National Park, Higuchi 32535 (NY); Highlands Co., Brass 20381 (NY); Long Key, Small 2038a (NY); Monroe Co. Redfearn 3106 (NY). VENEZUELA. Amazonas, Maguire et al. 53739 (MO); Apure, Davidse & González 14721 (MO); Bolivar Liesner & Morillo 13923 (MO); Carabobo, Liesner & Medina 13648 (MO); Delta Amacuro, Davidse & González 16472 (MO); Falcon, Steyermark & Braun 94560 (MO); Miranda, Steyermark & Davidse 116779 (MO); Monagas, Pursell et al. 8167 (MO); Portuguesa, Liesner et al. 12660 (MO); Sucre, Steyermark & Rabe 96065 (MO). VIRGIN ISLANDS. Allen 4273 (MO). 8. Taxithelium homalophyllum (Mitt.) Broth., Nat. Pflanzenfam. I(3): 1092. 1908. Stereodon homalophyllus Mitt., J. Proc. Linn. Soc. 7: 158. 1863. Plagiothecium homalophyllum A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1876–77: 445 (Gen. Sp. Musc. 2: 511). 1878.—TYPE: NIGERIA. Barter s. n. (holotype: NY!, isotype: BM!). Hypnum stenosekos Welw. & Duby, Mém. Soc. Phys. Genève 21: 438. 1 f. 2. 1872. Isopterygium stenosekos (Welw. & Duby) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1876– 77: 437, Sp. Musc. 2. 1878. Trichosteleum stenosekos (Welw. & Duby) A. Gepp, Cat. Afr. Pl. 2(2): 303. 1901. Taxithelium stenosekos (Welw. & Duby) Broth., Nat. Pflanzenfam. I(3): 1090. 1908.—TYPE: ANGOLA. Pungo Andongo, Welwitsch s. n. (holotype: BM!). Hypnum schweinfurthii Müll. Hal., Linnaea 39: 462. 1875. Taxithelium schweinfurthii (Müll. Hal.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1876–77: 423 (Gen. Sp. Musc. 2: 489). 1878.—TYPE: SUDAN. Mount Baginse, Schweinfurthii s. n. (isotypes: BM!, H!, JE!, S!, W!). Taxithelium glabratum Broth. & Geh., Bull. Herb. Boissier 4: 412. 1896.—TYPE: DEMOCRATIC REPUBLIC OF CONGO. Hens s. n. (holotype: H!, isotype: BR!). Taxithelium compressicaule Broth., Bot. Jahr. Syst. 24: 265. 1897.—TYPE: CAMEROON. Birundi, Dusén 758 (holotype: H!, isotypes: BM!, BR!, PC!, S!, UPS!). Taxithelium glabriusculum Broth., Bot. Jahr. Syst. 24: 266. 1897.—TYPE: LIBERIA. Monrovia, Dusén s. n. (lectotype designated here: H!, isolectotypes: PC!, S!). Trichosteleum andongense A. Gepp, Cat. Afr. Pl. 2(2): 303. 1901. Taxithelium andongense (A. Gepp) Broth., Nat. 834 SYSTEMATIC BOTANY Pflanzenfam. I(3): 1092. 1908.—TYPE: ANGOLA. Pungo Andongo, Welwitsch 112 (holotype: BM!, isotype: H!). Taxithelium perglabrum Broth. & Paris, Rev. Bryol. 30: 104. 1903.—TYPE: GUINEA. Puy-Age, Maclaud s. n. (isotypes: BR!, L!, PC!, S!). Taxithelium suboctodiceras Broth. & Paris, Rev. Bryol. 31: 121. 1904.—TYPE: GUINEA. Bandi, Pobeguin s. n. (holotype: H!, isotypes: L!, PC!, S!). Taxithelium pobeguinii Broth. & Paris, Rev. Bryol. 34: 99. 1907.— TYPE: GUINEA. Pobeguin s. n. (holotype: H!, isotypes: PC!, S!). Taxithelium nigerianum Broth. & Paris, Rev. Bryol. 38: 32. 1911.—TYPE: MALI. Bammako, sine legit (holotype: H!, isotypes: BR!, L!, M!, PC!, S!). Plants large, forming green-yellow or dark brown mats. Stems creeping, long–ascending, branched. Stem and branch leaves slightly differentiated; stem leaves larger and longer, erect-spreading, slightly concave, 0.90–1.12 mm long × 0.30–0.40 mm wide, ovate-lanceolate or oblong, margins entire; apex slightly serrulate, acute; costae short and double or absent; laminal cells linear, 40–50 × 2–3 μm, smooth, thin-walled, basal cells smooth; alar cells poorly differentiated, consisting of a triangular group with one enlarged and few supra alar cells, not inflated, not colored. Rhizoids evenly distributed along the stem. Perichaetial leaves 1.40–1.95 mm long × 0.35–0.45 mm wide, lanceolate, margins entire; apex aristate; costae absent; laminal cells linear, 50–65 × ca. 2 μm, thick-walled, smooth; alar cells poorly differentiated with 1 row, not inflated. Setae ca. 1.5 cm long. Capsules erect, asymmetric, ovoid, 0.6–0.8 mm long, constricted below mouth; exothecial cells subquadrate, not collenchymatous. Opercula short, conic, or obliquely conic-rostrate, ca. 0.3 mm long. Spores finely papillose, 15–20 μm across. Figures 11A–D. Distribution and Habitat—Taxithelium homalophyllum occurs from sea level to 916 m, mostly on tree trunks from tropical Africa in Angola, Cameroon, Congo (Zaire), Equatorial Guinea, Gabon, Guinea, Guinea-Bissau, Liberia, Mali, Nigeria, Sudan, Sierra Leone, and Togo, and from Surinam in the Neotropics (Fig. 13). Fig. 13. Distribution map for Taxithelium homalophyllum. [Volume 36 Discussion—This is the only other Taxithelium species that has smooth leaf cells, the other being T. leptosigmatum. As discussed for T. leptosigmatum, even though papillae are a distinctive character, this smooth species belongs in Taxithelium. The two papillae-lacking taxa can be easily differentiated, because T. homalophyllum has thin-walled leaf cells. In T. homalophyllum the perichaetial leaves are bigger and lanceolate, while in T. leptosigmatum they are smaller and more linear. They can be also distinguished by their geographic distributions, with T. leptosigmatum restricted to southeastern Asia and Australia, while T. homalophyllum is mostly from tropical Africa. A single specimen from Surinam was collected recently (2003) by Bruce Allen, which is a odd record, but the specimen fits with all the features of T. homalophyllum and therefore it is the only record of this species outside Africa. Nomenclatural Notes—The collector of the type material of Taxithelium nigerianum is unknown. The protologue states that the collection was done under the care of the Lieutenant governor of Haut-Senegal-Niger. It is well known that Paris, as a general, had military people collecting for him, so it is possible that the collector was a soldier under the command of the governor, forever to be unknown. Representative Specimens Examined—CONGO. sin. loc. Hens s. n. (H, BR). EQUATORIAL GUINEA. sin. loc. Patxi Heras 877/93 (NY). GABON. Issogho, Le Testu 450 (PC). GUINEA-BISSAU. Rio Muni, Niefang, Patxi Heras 877/93 (NY). SIERRA LEONE. sin. loc. Marmo s. n. (NY), Freetown, Arnell 2254 (PC). SURINAM. Sipaliwini, Allen 25237 (MO). TANZANIA. Kasanga, Büttner s. n. (PC, S). Acknowledgments. I express my gratitude to Bob Magill, Peter Stevens, Toby Kellogg, Bill Buck, Bruce Allen, Steven Churchill, Si He, Benito Tan, Yong Kien Thai, Monica Suleiman, Ahmad Damanhuri Mohamed, Haji Mohamed, Royce Longton, Jose Hidalgo, Jack Regalado, Micheline Carvalho–Silva, and the curators of the herbaria cited. Funds were provided by CAPES, Brazilian government, Missouri Botanical Garden, Whitney Harris World Ecology Center, and University of Missouri, St. Louis. Literature cited Anderson, L. E. 1954. Hoyer’s solution as a rapid permanent mounting medium for bryologists. The Bryologist 57: 242–244. Brummitt, R. K. and C. E. Powell. 1992. Authors of plant names. Kew: Royal Botanic Gardens. Buck, W. R. 1985. A review of Taxithelium (Sematophyllaceae) in Brazil. Acta Amazonica 15(Suppl.): 43–53. Buck, W. R. 1998. Pleurocarpous mosses of West Indies. Memoirs of the New York Botanical Garden 82: 1–400. Câmara, P. E. A. S. and E. A. Kellogg. 2010. Morphology and development of leaf papillae in Sematophyllaceae. The Bryologist 113: 22–33. Câmara, P. E. A. S. 2010. New combinations and one new name for the moss genus Taxithelium (Pylaisiadelphaceae). Novon 20: 139–142. Câmara, P. E. A. S. 2011. A re-circumscription of the moss genus Taxithelium (Pylaisiadelphaceae) with a taxonomic revision of subgenus Vernieri. Systematic Botany 36: 7–21. Câmara, P. E. A. S. and M. Carvalho-Silva. 2011. Taxithelium juruense (Broth.) Broth. (Pylaisiadelphaceae) an endangered Brazilian endemic, with notes on the genus Taxithelium for Brazil. Acta Botanica Brasilica 25: 198–202. Damanhuri, A. and R. E. Longton. 1996. Towards a revision of the moss genus Taxithelium (Sematophyllaceae). Annales Instituto de Biologia. Universidad Autónoma de Mexico, Series Botanica 67: 35–58. Gangulee, H. C. 1980. Mosses E. India Fascicle 8. Calcutta: Privately published. Goffinet, B. and W. R. Buck. 2004. Systematics of the Bryophyta (mosses): From molecules to a revised classification. Monographs in Systematic Botany from the Missouri Botanical Garden 98: 205–239. 2011] CAMARA: TAXITHELIUM Goffinet, B., W. R. Buck, and A. J. Shaw. 2009. Morphology, anatomy, and classification of the Bryophyta. Pp. 55–138 in Bryophyte biology Ed. 2., eds. B. Goffinet and A. J. Shaw. Cambridge: Cambridge University Press. Gradstein, S. R., S. P. Churchill, and N. Salazar-Allen. 2001. Guide to the bryophytes of tropical America. Memoirs of the New York Botanical Garden 86: 1–577. Lawrence, G. H. M., A. F. G. Buchheim, G. S. Daniels, and H. Dolezal. 1968: Botanico-Periodicum-Huntianum. Pittsburgh: Hunt Botanical Library. Magill, R. E. 1990. Glossarium polyglottum bryologiae: A multilingual glossary for bryology. Monographs in Systematic Botany from the Missouri Botanical Garden 33: 1–297. View publication stats 835 Ramsay, H. P., W. B. Schofield, and B. C. Tan. 2002. The genus Taxithelium (Bryopsida, Sematophyllaceae) in Australia. Australian Systematic Botany 15: 583–596. Sharp, A. J., H. A. Crum, and P. M. Eckel. 1994. The moss flora of Mexico. Memoirs of the New York Botanical Garden 69: 581–1113. Seki, T. 1969. A revision of the family Sematophyllaceae of Japan with special reference to a statistical demarcation of the family. Journal of Science of Hiroshima University 12: 1–80. Tsubota, H., H. Akiyama, T. Yamaguchi, and H. Deguchi. 2001. Molecular phylogeny of the Sematophyllaceae (Hypnales, Musci) based on chloroplast rbcL sequences. The Journal of the Hattori Botanical Laboratory 90: 221–240.