A Taxonomic Revision On Groutiella Steere (Orthotrichaceae, Bryopsida)

Groutiella Steere is a moss of the family Orthotrichaceae and is most closely related to the genera Macromitrium, Schlotheimia and Ulota. Geographically, it is distributed mainly in the tropical region area of the South and North America, Asia, Africa and Oceania, especially in Central America. This genus has never been revised monographically, except a few studies of American taxa. Fifteen species have been described. Among the characters of Groutiella, the followings are considered to be taxonomically important: (1) leaf basal margins consisted of several rows of narrow, elongate cells, (2) calyptra short and naked. For Groutiella, there are still some problems to be resolved: (1) this genus is confused with those related ones easily, should be clarified with more characters; (2) there are some confusions at the level of species, and they need to be further studied by checking type specimens. Finally, we consider that there is a strong necessity to have a revision on Groutiella.A total of 182 specimens from the various herbaria, including 13 type specimens were checked at the present study. Moreover, we also observed some specimens of Macromitrium, Schlotheimia and Ulota for clarifying the concept of the genus Groutiella further. In addition, we have researched the spores and peristomes of 10 species by SEM. It is the first time that this genus is revised in the world region taxonomically.The analysis of morphological characters for Groutiella showed that the most important diagnostic characters of this genus are the leaf differentiated border, peristome and shape of calyptra. The main differential characters between Groutiella and Macromitrium, Schlotheimia and Ulota are: (1) basal leaf cells round to rectangle; (2) marginal cells at base narrow and elongate; (3) calyptra short and naked; (4) peristome rudimental, only consisting of a low, papillose membrane. Taxonomy at the level of species depended mainly on the morphological characters of leaf, such as, leaf shape, apex, costa and leaf cells. The length of the margin differentiation and the basal cells can be considered as well. According to the shape of capsule, Allen has divided the genus into two groups, however, the author considered that Allen's opinion was incorrect. Although the shape and size of the capsule of Groutiella are different at the level of species, there is strong morphological polymorphism among populations and overlapping of characters exhibited among species. By the way, the changing of climate and environment usually result in the variation of capsule in shape and size.The author has observed several morphological characters which were neglected in the previous studies. (1) The peristome of Groutiella is a good diagnostic character among Orthotrichaceae, but the differences in the height and the pattern of the membrane is not significant to distinguish among species. (2) The stems of Groutiella have no central strand in the cross section, but there are no differences in the various species. (3) Axillary hairs exist in the most species of this genus, but their growing location, shape and the cell number are very similar among the species. (4) Perichaetial bracts are often considered as a character for classification, but in Groutiella, the perichaetial bracts have no or few differential from the branch leaves, except slightly shorter than them. (5) Observing by optical microscope and SEM, except G. apiculata and G. tumidula, the spores of Groutiella are isosporous, which are round and fine papillosa.The taxonomic revision of Groutiella Steere recognizes 9 species. Two species are treated as synonyms of other species, four species remain uncertain. Historical and nomenclatural reviews of Groutiella are introduced in detail. The following synonyms are suggested: Groutiella laxotorquata (C. Muell. ex Besch.) Wijk & Marg. is synonymous with G. tomentosa (Hornsch.) Wijk & Marg. Groutiella mucronifolia (Hook. & Grev.) Crum & Steere is placed under synonymy of G. apiculata (Hook.) Crum & Steere. Conclusively, 9 species of Groutiella are confirmed: Groutiella apiculata (Hook.) Crum & Steere, G. chimborazensis (Spruce ex Mitt.) Florsch., G. husnotii (Schimp. ex Besch.) Crum & Steere, G. maracaibensis (Broth.) Allen & Goffinet, G. obtusa (Mitt.) Florsch., G. reesei (Vitt) Allen, G. tomentosa (Hornsch.) Wijk & Marg., G. tuberculata Allen & Holz and G. tumidula (Mitt.) Vitt.