Taxonomic Revision Of The Brotherella (Sematophyllaceae, Musci)

The Brotherella M. Fleischer is a member of the Semtophyllaceae andmost of them distributed in the East Asia. Few species have been reported fromthe North America and South America. Since Fleischer proposed the genusBrotherella in 1914, 65 taxa have so far been known under this genus. Thegenus has proven extremely difficult to define specially at the species levelbecause of strong morphological polymorphism among populations andoverlapping of characters exhibited between species. Phytogeographically,Brotherella is a temperate genus, though most members of Sematophyllaceaeare tropical ones. There is no taxonomic revision work for Brotherella sinceFleischer found it.According to the past several year's study, author confirms that the genusBrotherella is a natural group, which is distinguished the other genera ofSematophyllaceae from the golden-yellow and glossy habit, 2-3 yellow andinflated alar cells and exthecial cell vertical walls thickening.The morphological studies on Brotherella exihibit that leaf is the mostimportant organ for determining species. The leaf shape, leaf margin and leafapice et al. are variable at the level of species, but these difference are stablefor the same species. All Brotherella have smooth and elongate leaf cells, andlaminal cells has been confirmed no taxonomic value on this revision. One ofthe prominent characters of Brotherella is well developed inflated alar cells.Although somewhat differing among the species, they are elliptic in shape andsituated at each extreme basal angle, being 3 in number. So alar cells is animportant character which different from the other genera. Inner perichaetialleaf fewly was discussed in the past studies. All Brotherella have broad ornarrowly tri-angular inner perichaetial leaves with the serrate at the apice. Theinner perichaetial leaf morphology have no clearly difference among thespecies.In 1960, Horikawa and Seki stated, "Shape and inclination of the capsuleare rather characteristic for each species.". Author considers that Horikawa and Seki's statement is incorrect based on this revised work. In fact, the shape andinclination of capsule are variable with the age. The exothecial cells are noncollenchymatous in all species, but longitudinally thickened. This is animportant characteristic of the genus Brotherella within the familySematophyllaceae. All species are of hypnoid form bearing both outer andinner peristomes in complete. The peristome of SEM shows that there is noevidently difference in the morphology for the distinct species. Horikawa andSeki (1960) considered that the cilia seem to be important in classification ofthe species. But the cilia characters have not expressed the taxonomic value atthe level of species based on author's observation. The spores are ratherconstant in size and shape (usually is globose, 19-25μm in diameter), and theyare usually smooth.Author considers the strong differentiation of stem and branch leaves, the2-3-pinnately branching system and the nearly entire leaf margins seen in manyspecies of Wijkia as the three important features separating Wijkia fromBrotherella. In some species of Wijkia (eg. Wijkia hornschuchii), stem leave aresimilar to branch one in the shape. Oppositely, some species of Brotherella (eg.Brotherella longipes) stem leaves are differentiated from branch ones. In fact,there are some confusion between the Brotherella and Wijkia in the conceptionof genera. So there is necessity to make a revision on Wijkia. The systemicrelationship between Brotherella and Wijkia need to further research in thefuture. Phytogeographically, the distribution of Wijkia is wider than one ofBrotherella. Therefore, author guess that the Wijkia probably early diversedorigined than Brotherella in the evolution.Brotherella also is related to Pylaisiadelpha. The two genera haveregarded congeneric by some authors and Pylaisiadelpha is the senior name ofthe combined genus. Based on the recent study, species of Brotherella can bedistinguished further from Pylaisiadelpha by the toothed margins towards theleaf apex. The leaves of Pylaisiadelpha, as in Wijkia, have nearly entiremargins, except becoming toothed at the very distal tip. Alar cell morphology is the most important diagnosis for Brotherella and Pylaisiadelpha. InPylaisiadelpha, alar region is consisted of 2-3 clourless, inflated alar cells and3-5 small, hyaline supra-alar ones.Hypnum is similar to Brotherella with the glossy, the falcate leaves,hypnoid peristome and lanceolate inner perichaetial leaves, but the former isdistinguished the latter from having not 2-3 yellow inflated alar cells. Somespecies of Hypnum have 2-3 inflated alar cells, but alar cells are clourless, arenot yellow or brownish. Hypnum is a large and diverse group. Hypnum is ratherdifficult genus in classification of species. Some species have been transferredto the other genera in the previous studies. There is a strong need for a revisionon Hypnum.The Sematophyllum is similar to Brotherella in the inflated alar cells, butthe former is differeted the latter from the exothecial cells collenchymatous. Inaddition, the inner perichaetial leaf margins are entire or nearly entire inSematophyllum, but are serrate at apices in Brotherella.In the present study, Brotherella M. Fleischer is revised on a worldwidebasis. Historical and nomenclatural reviewers of Brotherella are presented indetail. The following synonyms and new combinations are made: Brotherellaamblystegia (Mitt.) Brotherus and Brotherella dixonii Herzog are respectlytransferred to Heterophyllium amblystogium (Mitten) Y. Jia et S. He andHomomallium dixonium (Herzog) Y. Jia et S. He. Brotherella coreana Sakurai,Brotherella otii Sakurai and Brotherella harveyana (Mitten) Dixon aresynonymous with Pylaisiadelpha tenuirostris (Bruch & Schimper ex Sullivant)Buck. Brotherella crassipes Sakurai is placed under synonymy of Brotherellacurvirostris (Schwagrichen) Fleischer. Brotherella herbacea Sakurai issynonymous with Brotherella henonii (Duby) Fleischer. One new species isrecognized: Brotherella cuspidate Y. Jia et J. M. Xu. In addition, Brotherellacomplanata Reim. et Sak. is a new record for China, B. erythrocaulis and B.fauriei are firstly reported in the North America in the present study.Conclusively, 14 species of Brotherella are confirmed: Brotherella erythrocaulis (Mitten) Fleischer; B. nictans (Mitten) Brotherus; B. curvirostris(Schw(?)grichen) Fleischer; B. henonii (Duby) Fleischer; B. fauriei (Cardot)Brotherus; B. falcata (Dozy et Molkenboer) Fleischer; B. complanata Reimerset Sakurai; B. opaeodon (Sullivant) Brotherus; B. luzonensis (Brotherus)Fleischer; B.recurvans (Michaux) Fleischer; B. longipes Brotherus; B,deplanatula (Cardot) Brotherus; B. minulate Bartram; B. cuspidata Y. Jia et J.M. Xu.The taxonomic value of leaf, laminal cell, alar cell, perichaetical leaf,capsule and peristome are re-evaluated in this revision. Key to the species ofBrotherella is provided. Detailed descriptions and illustrations of each taxon ofBrotherella are provided. The relationships with the other related genera arediscussed.