Lopholejeunea nigricans (Lindenb.) Schiffn.
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Authority
Gradstein, S. Robbert. 1994. Lejeuneaceae: Ptychantheae, Brachiolejeuneae. Fl. Neotrop. Monogr. 62: 216. (Published by NYBG Press)
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Family
Lejeuneaceae
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Scientific Name
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Type
Type. Java, unknown collector (holotype, W; isotype, G).
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Synonyms
Phragmicoma fischeriana Nees, Lopholejeunea muelleriana (Gottsche) Schiffn., Lejeunea abortiva Mitt., Lejeunea mariei (Spruce) Besch., Lejeunea rusbyi Spruce, Lejeunea atroviridis Spruce, Lopholejeunea andersonii Steph., Lopholejeunea rivularis Steph., Lopholejeunea spinosa Steph., Lopholejeunea fragilis Steph., Lopholejeunea abortiva (Mitt.) Steph., Lopholejeunea apiahyna Gottsche ex Steph., Lopholejeunea muelleriana (Gottsche) Schiffn., Lopholejeunea muelleriana subsp. floridana R.M.Schust., Lejeunea nigricans Lindenb., Symbiezidium nigricans (Lindenb.) Trevis., Lejeunea fischeriana Nees, Symbiezidium fischerianum (Née) Trevis., Lopholejeunea nigricans (Lindenb.) Schiffn., Lopholejeunea subfusca (Nees) Schiffn., Schiffneriolejeunea polycarpa (Nees) Gradst., Lejeunea muelleriana Gott, Lopholejeunea abortiva (Mitt.) Steph., Lopholejeunea mariei (Besch. & Spruce) Steph., Lopholejeunea rusbyi (Spruce) Steph., Lopholejeunea atroviridis (Spruce) A.Evans, Acrolejeunea atroviridis (Spruce) Steph. ex Spruce
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Description
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Species Description - Autoicous or dioicous. Plants to 4 cm long × 0.8-1.4 mm wide, glossy, brown green to blackish when dry. Branching irregularly pinnate, usually Lejeunea-type, rarely Frullania-type, recurved flagelliform branchlets occasionally present on lower portions of stem. Stems in cross section ca. 7-10 cells across, composed of ca. 10-20 epidermal cells surrounding 15-40 medullary cells, all cells thin-walled with colorless walls, epidermis symmetric or asymmetric, dorsal epidermal cells as large as or smaller than ventral epidermal cells. Leaves contiguous to imbricate, dorsal lobe asymmetrically ovate-oblong, 0.5-1 × 0.3-0.7 mm, apex rounded, obtuse or acute-apiculate, plane or recurved, margins entire, occasionally slightly toothed above, dorsal base rounded, ventral margin forming an angle of 100-150° with the keel; leaf cells in mid-leaf ca. 20-35 µm, trigones small to medium-sized, simple triangular to radiate, intermediate thickenings frequent, small; oil bodies (Schuster, 1980) 8-20 per median leaf cell, homogeneous, small, Massula-type. Lobules ovoid-oblong, sometimes reduced, when well-developed 0.3-0.45 × 0.2-0.3 mm, up to l/2× lobe length, weakly to strongly inflated along the keel, usually flattened distally, free margin without or with a one-celled tooth, at distal end attached to lobe surface by only one cell. Underleaves distant to subimbricate, transversally ovate to suborbicular, variable in size, ca. 0.2-0.5 mm long × 0.2-0.7 mm wide, 2-5× stem width, apex plane or recurved, bases cuneate or rounded, insertion line curved to arched (less than 100 µm deep). Androecia on short or long branches, bracts in 3-10 series. Gynoecia on short or long branches, without true subfloral innovations, occasionally with pseudo-innovation of the Lejeunea-type, bract lobes asymmetrically ovate-oblong, 0.8-1.2 × 0.6-0.8 mm, apex obtuse to acute-apiculate, rarely rounded, margin toothed to subentire above, lobule narrow rectangular-ligulate, hardly elongated beyond the keel, up to 2/3 × lobe length, sometimes reduced, margin entire or with a few teeth; bracteoles orbicular to oblong, rarely broadly ovate, 0.7-1 mm long, apex rounded or truncate-emarginate, margins plane or recurved, usually entire, rarely with a few teeth. Perianths exserted to 1/3-2/3, obpyriform, apex broad truncate, with 4-5 sharp, more or less winged, dentate-ciliate to laciniate keels: 2 lateral keels, 2 ventral keels and 1 dorsal keel which may be short or lacking altogether, teeth and laciniae up to 10 cells long (sometimes weak, perianth subentire), near perianth apex becoming randomly distributed, an additional row of lacinia sometimes developed on the dorsal side and on the ventral side between the two ventral keels; beak ca. 5 cells long. Sporophyte as in the genus.
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Discussion
Lopholejeunea nigricans grows on trunks, lianas, poles, and logs, mainly at forest edges and along creeks, in humid environments. The species is also common on rocks and boulders in meadows and streams.
The neotropical distribution of Lopholejeunea nigricans overlaps with that of L. subfusca, but the latter is basically a lowland species and rather xerophytic. Lopholejeunea nigricans is more common at higher elevations, above 300 m, and less tolerant of desiccation. Towards higher latitudes, e.g., southeastern Brazil and the United States, L. nigricans also occurs at sea level and here the two species may grow side by side. In the New World Lopholejeunea nigricans has commonly been known as L. muelleriana. Study of a number of collections of the Asiatic L. nigricans from the herbarium of Leiden has convinced me that the two are conspecific. I am indebted to Dr. Mizutani (pers, comm.) for confirming the conspecificity of the two. As the name L. nigricans antedates L. muelleriana, the former name has priority.Lopholejeunea nigricans is the most widespread species of the genus in the neotropics and quite variable. It has been described in the past under many different names. The species can be distinguished most readily by its emergent perianth and its pointed female bracts. The perianth may be 4- or 5-keeled depending on whether a dorsal keel is developed, and the leaves may be rounded or acute. An interesting feature of neotropical L. nigricans not mentioned by previous authors, is the fact that the stem epidermis may be quite asymmetric, with one or two dorsal epidermal cells smaller than the ventral epidermal cells. Populations with symmetric epidermis (dorsal cells = ventral cells) do also occur, however.Lopholejeunea nigricans is the only species of the genus Lopholejeunea in the neotropics which may produce populations with purely sharply acute-apiculate leaves (described as L. apiahyna Steph. and L. muelleriana subsp, muelleriana sensu Schuster, 1980). Acute leaves may also be observed in L. quelchii, but in that species they always occur mixed with rounded leaves. Occurrence of both rounded and acute leaves on a single plant is also common in L. nigricans. In addition, many populations have rounded leaves only (described as Z. rivularis Steph. and L. muelleriana subsp. puertoricensis Schust.), including those from the United States and the West Indian islands.Lopholejeunea abortiva (Mitt.) Steph. from tropical Africa is conspecific with L. nigricans, as was already suggested by VandenBerghen(1984). The African populations exhibit a variation somewhat similar as in the neotropics and two varieties were recognized by VandenBerghen: L. abortiva var. abortiva with a rounded leaf apex and perianth without dorsal keel, and L. abortiva var. fragilis (Steph.) VandenBerghen with a pointed or rounded leaf apex and a perianth furnished with a dorsal keel. The varieties apparently correspond with L. muelleriana subsp. puertoricensis Schust. and L. muelleriana subsp. muelleriana, except for the fact that female bracteoles are as a rule denticulate in African var. fragilis. In the neotropics female bracteoles are normally entire or sinuate and in only very few instances denticulate bracteoles have been observed in L. nigricans. Another difference seems to be the frequent occurrence in African populations of female bracts with entire margins and rounded apex. In tropical America rounded female bract apices are observed only very rarely (they are characteristic of L. subfusca!) and I have never seen forms with entire bract margins.According to VandenBerghen (1984), the two African varieties of L. abortiva have a different geographical range, var. abortiva being a lowland plant whereas var. fragilis occurs at higher elevations. In tropical America, I have also noted that forms with pointed leaves occur at higher elevations only, whereas forms with rounded leaves are more common in lowland areas. As noted above, rounded and pointed leaves may often occur on single plants; in addition, the development of a dorsal perianth keel is subject to variation within single specimens. The entire range of variation can be seen in collections of L. nigricans from Casanare, Colombia, ca. 1150 m (Aguirre & Gradstein 3030, 3044, 3079).Thiers and Gradstein (1989) have recently reported L. nigricans (as L. muelleriana) from Australia. They recognized two varieties, var. muelleriana and var. australis, each with a different geographical range. The variation exhibited by the Australian plants largely falls within the range of variation in the New World except for the presence of almost smooth perianth keels in var. australis.In this treatment I have chosen not to recognize infraspecific taxa in Lopholejeunea nigricans as the morphological differences observed among the neotropical populations are by no means sharp. A detailed biosystematic study of L. nigricans should be undertaken to assess the variation exhibited by this interesting taxon. As Vanden-Berghen (1984) has pointed out, such a study should focus on the entire range of the species, not just on the materials of one continent.Lopholejeunea nigricans may be confused with L. subfusca and sterile material cannot always be identified with certainty. Differences between the two are discussed under L. subfusca.Distribution: Pantropical. In the neotropics a widespread species, reaching northwards to North Carolina, southwards to SE Brazil, Bolivia and Juan Fernandez, from sea level to 1800 m. The populations of Lopholejeunea nigricans from the Juan Fernandez Islands, where the species was known as L. spinosa Steph., constitute a remarkable disjunction of the species. Lopholejeunea nigricans is also common in Africa, where it has been known as Lopholejeunea abortiva (VandenBerghen, 1984), and in Southeast Asia (Mizutani, 1979). Theirs and Gradstein (1989) have recently recorded the species from Australia (as L. muelleriana).
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Objects
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Distribution
Mexico North America| Chiapas Mexico North America| Costa Rica South America| Cocos Island Costa Rica Central America| Panama Central America| Panamá Panama Central America| United States of America North America| North Carolina United States of America North America| Florida United States of America North America| Cuba South America| Jamaica South America| Puerto Rico South America| Guadeloupe South America| Dominica South America| Saint Vincent and the Grenadines South America| Colombia South America| Casanare Colombia South America| Meta Colombia South America| Risaralda Colombia South America| Santander Colombia South America| Venezuela South America| Amazonas Venezuela South America| Miranda Venezuela South America|