The Genus Rectolejeunea in India

Abstract

Two species of Rectolejeunea (R. olivacea (Steph.), comb. nov. and R. brittoniae Evans) are reported from western ghats, India. The former was earlier known from the eastern Himalayas only as R. subacuta whereas the latter is a new record for India. The genus Rectolejeunea Evans has close affinities with the genus Lejeunea Lib. and a remote relationship with Cheilolejeunea (Spruce) Schiffn. It is very close to the former in the position of the hyaline papilla and to the latter in dull texture of the plants, flattened perianth and usually few coarsely segmented, large oil-bodies. Rectolejeunea is easily separable from Cheilolejeunea by the proximal position of the hyaline papilla in the lobule, and is characterized by the following distinctive features (Schuster 1980): (i) The ability to produce caducous leaves, (ii) the compressed perianth with antical keel low or absent, (iii) usually the reduction of leaf lobules to a few cells with elongated and pluricellular apical tooth, (iv) usually 1-2 and often more coarsely segmented large oil-bodies and (v) tendency toward asexual reproduction. Some other characters, in combination with the above, also help in segregating Lejeunea and Rectolejeunea. For instance, in Rectolejeunea (i) leaf cells are usually hexagonal with minute trigones or evenly thick-walled having smaller marginal cells, (ii) underleaves are obovateorbicular, 2-3 times of the stem width, deeply bifid with a broad sinus and crenulate margin, and (iii) male bracteoles are present throughout the antheridial shoot. The genus is widely distributed in India but so far there are records of only two species: R. subacieta Steph. from Sikkim Himalayas (Stephani 19121917) and R. aloba (Sande Lac.) Steph. from peninsular India (Pande & Misra 1943). The plants described by Pande and Misra (1943) under R. aloba do not resemble the isotype of R. aloba but seem to be some other species of genus Lejeunea. Also the plants described by Stephani (1914) under R. aloba do not seem to be a species of Rectolejeunea but of Lejeunea. The recent collections from south India revealed the presence of two species ofRectolejeunea, ofwhich one is referable to R. olivacea (Steph.), comb. nov. and the other to R. brittoniae Evans. The details of both the species, collected from south India, have been provided. Rectolejeunea olivacea (Steph.) Srivastava et Agarwal, comb. nov. (Fig. 1-22) Eulejeunea olivacea Steph., Hedwigia 29: 85, Mar., Apr. 1890. Lejeunea olivacea (Steph.) Steph., Hedwigia 29: 137, MayJun. 1890 (non Lejeunea olivacea (Hook. f. et Tayl.) Gott. et al., Synop. Hepat.: 334, 1845). Rectolejeunea subacuta Steph., Spec. Hep. 5: 700, 1914 (synonymized by Mizutani 1965). Lejeunea subolivacea Mizut., Journ. Hattori Bot. Lab. 28: 121, 1965 (a substitute name for L. olivacea (Steph.) Steph. 1890, non (Hook. f. et Tayl.) Gott. et al. 1845). Plants 3-7 mm long, brownish-yellow, branching Lejeunea type; stem in cross section (45-55 gm in diameter) with 7 cortical and 3-4 comparatively smaller medullary cells, cells evenly thick-walled. Leaves distant to imbricate, widely spreading, orbicular, 0.32-0.48 mm long, 0.30-0.40 mm wide, margin somewhat wavy, apex rounded, cells thickwalled with very minute trigones, marginal cells 1014 x 9-12 gm, median cells 15-21 x 12-18 gm, basal cells 21-27 x 14-18 gm; leaf lobules variable in shape and size on the same axis, usually highly reduced at basal portion and inflated at apex, when fully developed 1/3 of the lobe length, first tooth 14 celled, elaborated with hyaline papilla at its apex. Underleaves suborbicular, 0.08-0.16 mm long, 0.07-0.15 mm wide, bilobed for 1/2 of their length, lobes divaricate, acute at apex, margin at places crenulate due to the projecting cells, attached to the stem by almost straight line, rhizoidal portion not differentiated. Asexual reproduction rare. Monoecious. Male inflorescence either terminal or intercalary on main axis or on short lateral branch, bracts in 3-4 pairs, imbricate, rounded at apex; bracteoles either present throughout or only at base. Female inflorescence terminal either on main axis or on lateral branch with one subfloral innovation, bractlobe oblong, 0.44-0.50 mm long, 0.33-0.40 mm wide, margin smooth or wavy, apex rounded-obtuse; bract lobule oblong, 0.24-0.30 mm long, 0.100.13 mm wide, usually acute at apex, adnate with lobe for almost all of its length; bracteole ovate, 0007-2745/86/195-199$0.65/0 This content downloaded from 157.55.39.25 on Mon, 25 Jul 2016 04:40:46 UTC All use subject to http://about.jstor.org/terms 196 THE BRYOLOGIST [Volume 89