Monographs Details: Acanthocoleus aberrans var. laevis Gradst.
Authority: Gradstein, S. Robbert. 1994. Lejeuneaceae: Ptychantheae, Brachiolejeuneae. Fl. Neotrop. Monogr. 62: 216. (Published by NYBG Press)
Family:Lejeuneaceae
Synonyms:Lejeunea loxensis Gottsche ex Gottsche, Lindenb. & Nees, Lejeunea caldana Ångstr., Dicranolejeunea setacea Steph., Dicranolejeunea renauldii Steph., Homalolejeunea corcovadensis Steph., Odontolejeunea paulina Steph., Cyclolejeunea paulina (Steph.) Steph., Dicranolejeunea paulina Gottsche ex Steph., Dicranolejeunea rotundata A.Evans, Thysananthus schiffneri S.W.Arnell, Dicranolejeunea loxensis (Gott ex Gott, Lindenb. & Nees) Steph., Acanthocoleus aberrans (Lindenb. & Gottsche) Kruijt
Description:Species Description - Autoicous. Plants 1-2 cm long × 0.6-1.5 mm wide, yellowish green to brown. Stems 0.1-0.15 mm in diam., in cross section composed of 9-12 epidermal cells surrounding 17-40 medullary cells, dorsal epidermal cells about as large as the ventral epidermal cells; ventral merophyte two cells wide. Leaves contiguous to imbricate, dorsal lobe ovate, 0.5-0.9 × 0.4-0.7 mm, apex apiculate to short acuminate, rarely rounded, margins entire to toothed near apex with 1-5 teeth, the teeth consisting of 1-6 cells, ventral margin forming an angle of ca. 90-170° with the keel; median cells ca. 30-40 × 25 µm, with very small, cordate trigones; oil bodies small, 10-15(-25) per cell, finely segmented, Jungermannia-type, ellipsoid to subglobose, ca. 2-6 × 2-2.5 µm. Lobules ovate, up to 0.3 mm long, l/4-l/3× lobe length, often reduced, keel arched, free margin with 1-2 teeth separated from each other by 3-7 margin cells, first tooth (1)2-4 cells long, inflexed, second tooth smaller, 1-2 cells long, sometimes obsolete. Underleaves subimbricate, 0,2-0.4 mm, 2-3× stem width, margins plane or slightly recurved, insertion line arched. Androecia as in var. aberrans. Gynoecia with (l-)2 innovations, innovations often fertile, bract lobes ovate-oblong, up to 0.7 mm long, apex apiculate to short acuminate, margins entire or toothed near apex with 1-5 teeth, lobule small, up to l/5× lobe lenght, sometimes reduced, keel smooth; bracteoles 0.5-0.6 mm long, margins plane or narrowly recurved. Perianths obcuneate, up to 1 mm long × 0.6-0.7 mm wide, emergent to 1/3-1/2, rather flattened, with 2 sharp lateral keels and one swollen, rounded, broad or narrow ventral keel, the lateral keels usually winged over 1/2 or more of perianth length and dentate to ciliate above, cilia up to 10 cells long and 1-3 cells wide, occasionally wings and cilia reduced, the ventral keel smooth or with a few ciliae; beak 2-4 cells long. Sporophyte as in the genus; seta with 16 outer rows of cells throughout its length.

Discussion:Acanthocoleus aberrans var. laevis is the most common and widespread taxon in the genus. All records from the South American mainland, except those from French Guiana, are referable to this taxon. In addition, African records of A. aberrans may also belong to this variety. In Central America and the West Indies, both var. laevis and the typical variety of A. aberrans occur.

Acanthocoleus aberrans var. laevis stands out by its perianth with a smooth ventral surface, lacking sharp keels (as in Dicranolejeunea axillaris). Occasionally a few ciliae are produced at the lateral edges of the swollen ventral perianth surface (e.g. Guadeloupe, Duss 440) but sharp ventral keels are never produced. In var. aberrans, on the other hand, the ventral surface of the perianth has (l-)2 sharp, ciliate ventral keels. Besides their different perianths, the two varieties tend to differ in a few other morphological traits, none of these being constant, however. In var. laevis innovations are always paired and frequently fertile, leaf lobules are frequently reduced, and leaf apices are sometimes rounded instead of pointed. In the typical variety of A. aberrans, innovations are mostly single (sometimes paired) and usually sterile, the lobules are never (?) reduced, and the leaf apex is always pointed, never rounded.

The cilia of the perianth vary considerably in length and may become reduced. Forms with subentire perianths, only bearing a few scattered teeth near apex, occur frequently near the southern limits of the range (e.g. collections from Paraguay, leg. Geissler).

Some collections of Acanthocoleus aberrans var. laevis, including the types of Dicranolejeunea rotundata Evans, D. renauldii Steph. and D. setacea Steph., have been misidentified as Brachiolejeunea phyllorhiza by Kruijt and Gradstein (1986). For differences with that species see under the latter. Acanthocoleus aberrans var. laevis is also very similar to Dicranolejeunea axillaris; differences have been discussed above under the genus. Sterile specimens with rounded leaf apices cannot be distinguished from A. trigonus.
Distribution:Mexico North America| Distrito Federal Mexico North America| Oaxaca Mexico North America| Tamaulipas Mexico North America| Cuba South America| Granma Cuba South America| Guantánamo Cuba South America| Santiago de Cuba Cuba South America| Villa Clara Cuba South America| Jamaica South America| Haiti South America| Guadeloupe South America| Colombia South America| Boyacá Colombia South America| Cundinamarca Colombia South America| Magdalena Colombia South America| Tolima Colombia South America| Lara Venezuela South America| Mérida Venezuela South America| Ecuador South America| Galápagos Islands Ecuador South America| Peru South America| San Martín Peru South America| Brazil South America| Distrito Federal Brazil South America| Minas Gerais Brazil South America| Paraná Brazil South America| Santa Catarina Brazil South America| São Paulo Brazil South America| Cochabamba Bolivia South America| Tarija Bolivia South America|