A Preliminary Treatment of the Genus Campylopus (Musci: Dicranaceae) in Central America Bruce H
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63 Tropical Bryology 1: 63-94, 1989 A preliminary treatment of the genus Campylopus (Musci: Dicranaceae) in Central America Bruce H. Allen Missouri Botanical Garden P.O. Box 299 St. Louis, Missouri 63166-0299, U.S.A. Abstract. There are 26 species of Campylopus in Central America. They are divided into three groups on the basis of two characters: the presence or absence in the costa of a ventral layer of enlarged, hyaline cells and the presence or absence in the stem of an outer hylodermis. Dicranum costaricensis Bartr. is transferred to Campylopus as C. valerioi nom. nov. Campylopus hoffmanii and C. standleyi are recognized as distinct species. Six new synonyms are proposed: C. straminifolius = C. densicoma; C. costaricensis = C. surinamensis; C. roellii = C. tallulensis; C. donnellii = C. zygodonticarpus; C. tuerckheimii = C. zygodonticarpus; C. sargii = C. zygodonticarpus. The genus Campylopus is a large and taxono- are occupied by groups of species whose characters mically complex group of world-wide distribu- exhibit shades of variation in reticulate tion. Frahm (1988) considers the genus to have combinations. As presently understood, the only originated in the subantarctic region of the world; features common to all species of the genus are: in terms of species numbers the group is most 1. dioicous sexual condition, 2. broad, single, diversified in Central and South America. excurrent costae, 3. estomatate capsules and 4. There is a remarkable amount of variation setae sinuose when moist. found in nearly all characters of Campylopus, and A consideration of the genera near Campylo- as a result the generic limits of the genus are pus makes it apparent that the above character diffuse. There is, however, a group of species that states are generalized. The character state that has is readily recognized as belonging to Campylopus. been given the greatest weight in defining the This group consists of medium to large, dioicous genus is the sinuous seta. The questionable value mosses with stiff, erect to spreading, (generally of this character state in defining Campylopus has unbordered), linear leaves. They have broad, been discussed by Frahm (1983). Simply stated, excurrent costae approximately 1/2 to 2/3 the leaf its presence in a number of other closely related width at base. The leaves in cross-section have genera, and its presence in the genus costae with a ventral layer of variously enlarged Dicranoweisia points to the multiple evolution hyaline cells (hyalocysts) and a well-developed of the character state in the family. Furthermore, dorsal stereid band. The upper leaf cells are firm- the presence of generic pairs whose species are walled and shortly oblong, and the alar cells are gametophytically nearly identical yet differ in differentiated. Sporophytically the setae are si- the condition of the their setae (Atractylocarpus- nuous when moist, the exserted capsules are cur- Dicranodontium; Dicranella-Campylopodium; ved, stomata are absent, and the peristome teeth Paraleucobryum- Campylopus p.p.; Pilopogon- are similar to those of Dicranum. The calyptrae Campylopus p.p.) provides additional evidence are cucullate and in many species the base of the that the sinuose setae has evolved several times calyptra is ciliate but the opposing character in the group. state, calyptra entire at base, is also common. There have been a number of attempts at Although in the typical sense Campylopus is subdividing Campylopus (see Frahm 1982b). easy to recognize, the generic edges of the genus Usually the genus has been divided along lines corresponding to variations in the arrangement of 64 chlorocysts, hyalocysts, and stereid cells of the into the lamina, ventral hyalocysts in the costa costa. But, a number of Campylopus species and erect capsules, it appears to belong to Group exhibit costae that are intermediate in form B of Campylopus (see key). between two or more costal types and it has been shown (Florschütz & Florschütz-de Waard 1974) Campylopus Brid., Musc. Rec. Suppl. 4: 71. 1819. that transitional forms between subgenera can be found in serial sections of a single leaf. As a result Plants small to robust, densely tufted. Stems more recent classifications of Campylopus do not sparsely branched often densely tomentose, leaf utilize the form of the costa as seen in cross- rhizoids frequently arising from cells on the lower section. Certainly, the development of dorsal dorsal surface of the costa; stems in cross-section stereid cells in the costa of Campylopus is variable with a well-developed central stand of small, to the degree that this character can not be used thin-walled, hyaline cells, inner cortex of large, in subdividing the genus. On the other hand, the hyaline to yellowish, thin- or firm-walled cells, presence or absence of a ventral layer of thin- outer cortex of smaller, thick-walled, dark-reddish walled hyaline cells in the costa has not been cells, epidermis of enlarged hyaline cells present reported to be a variable feature and in this study or absent. Leaves erect, flexuous, or spreading, was found to be a diagnostic character of two ovate-lanceolate, to ovate-subulate, margins groups of Campylopus species. Furthermore, this incurved, variably toothed, nearly always feature is supportive of Frahm’s (1983) division denticulate at the extreme apex; costa very broad of the genus into groups based on such features as below, occupying most of the leaf above, capsule position, peristome shape, spore mor- percurrent to excurrent, often ribbed or mamillose phology, stem cross-section and costa shape as at back, at times with multi-cellular lamellae; viewed from the surface. basal cells elongate, thin- walled or incrassate, Frahm (1983) recognized the artifical nature of alar cells almost always present and usually well- Campylopus, but he did not give his categories developed, upper cells quadrate, oval, rhombic, generic rank on the grounds that it was not possible oblong, rhomboidal or elongate, usually in to vegetatively recognize them. In this study oblique rows, incrassate, marginal cells at base three groups of Campylopus could be recognized some times forming a hyaline border; cells smooth, on the basis of two gametophytic characters: 1. a porose or entire. Dioicious. Setae strongly ventral layer of thin- walled, hyaline cells present/ cygneous when moist; capsules exserted, ovoid absent in the costa; 2. stem with/without a to ellipsoid, struma present or absent, usually hyalodermis. There are 26 Central American striate when dry, erect or curved; stomata absent; species of Campylopus and for the most part they annulus present; peristome teeth haplolepide- fall cleanly into the above three groups of ous, the 16 peristome teeth divided 1/2 to nearly Campylopus. There is one subgroup of their full lengths into two filaments, generally Campylopus, however, that is difficult to place. striate on the outer surface, papillose on the inner This subgroup (consisting of C. tallulensis, C. surface; opercula rostrate; calyptrae cucullate, fragilis, and C. heterostachys) has stem epidermal frequently fringed at base by long, single- celled cells that are somewhat enlarged and variably hairs. Spores 12-16 µm, yellow to brown, variously thin-walled. The stem epidermal cells in this papillose. group may appear as a typical hylodermis, more commonly they are only moderately enlarged and while the outer walls of the epidermal cells are thin-walled the lateral walls are usually firm- walled. The subgroup can be recognized by its basal leaf cells that are thin-walled and lax. In two members of the subgroup (C. tallulensis and C. heterostachys) the basal cells extend up the Key to the Campylopus groups margins of the leaf in a V-shaped pattern. Since the subgroup has a costa that is gradually narrowed 65 1. Costae in cross-section without a ventral layer 5. All leaves with long hair points; plants wi of hyaline, thin-walled cells ........ Group A thout comal tufts................ 2. C. richardii 5. Only the uppermost leaves with short hyaline 1. Costae in cross-section with a ventral layer of tips; plants with comal tufts ........................... hyaline, thin-walled cells ................................ 2. 4. C. valerioi 2. Stems in cross-section with outermost layer of 6. Basal leaf cells smooth ............................. cells larger and thinner-walled then cells just 3. C. savannarum below; costa gradually narrowed into the lamina 6. Basal leaf cells porose ............................. 7. .......................................................... Group B 7. Upper leaf cells quadrate ............................. 2. Stems in cross-section with outermost 2-3 5. C. weberbaueri layers of cells small and thick-walled; costa 7. Upper leaf cells oval, oblong rhomboidal abruptly contracted to the lamina ...... Group C ............................................................... 8. 8. Leaves at base with a short, hyaline bor der, most leaves over 10 mm long; basal and median cells strongly porose; The species of Group A are gametophytically plants with comal tufts .............................. distinct from the other members of Campylopus 4. C. valerioi but similar to Pilopogon, Dicranodontium, 8. Leaves elimbate, less than 10 mm long; Atractylocarpus and Chorisodontium in having cells moderately porose at base only; ventral stereid cells in the costa rather than plants without comal tufts ........ enlarged ventral hyalocysts. Only the presence of ....................................... 1. C. arctocarpus a cyneous seta