Cheilolejeunea luensis C.J. Bastos, A.M. Sierra & C.E. Zartman, 2025

Cheilolejeunea luensis C.J. Bastos, A.M. Sierra & C.E. Zartman , sp. nov. Fig. 2–3 View FIGURE 2 View FIGURE 3 .

Plant similar to Cheilolejeunea aneogyna but differing in its androecial branches with bracteoles present throughout the spike, large, subrectangular leaf lobules, ca. 1/2−2/3 of the leaf lobe, keel with strongly mammillose cells, ventral merophytes 2−3 cells wide, and occasional presence of pseudo-innovations, and leaf lobe margins formed by two rows of quadrate cells.

Type:— BRAZIL. Amazonas: Manaus, Rio Negro , Praia da Lua, 3°02’04.9”S 60°09’32.5”W, floresta sazonalmente inundada (Igapó), epífita, 25 November 2016, A. M. Sierra 4590 ( holotype INPA; isotype ALCB) GoogleMaps .

Main axis with leaves 0.9−1.2 mm wide, branches Lejeunea - type. Stems 80 µm in diameter, in cross section with 7 epidermal cells and 10−11 medullary cells, ventral merophytes 2−3 cells wide. Leaves imbricate, spreading to suberect; leaf lobes ovate-oblong, convex, 410−560 µm long × 320−490 µm wide, dorsal margins slightly arched, crenulate to entire, ventral free margins straight, entire to crenulate, apices rounded, curved; lobe margins formed by two rows of quadrate cells; leaf cells oblong to hexagonal, basal cells 20−30 µm long × 15−23 µm wide, median cells 15−20 µm long × 13 µm wide, strongly mammillose, trigones small to median, intermediate thickenings 0−1 per cell; oil bodies not seen; ocelli absent; lobules oblong to oblong-subrectangular, large, 160−230 µm long × 95−115 µm wide, ca. 1/2−2/3 of the leaf lobe length, weakly inflated, free antical margin slightly involute, 8−10 cells long, lobule apices with two small, tightly associated teeth, apical free margin curved to oblique, keel slightly arched to straight, crenate due to mammillose cells; reduced lobules not observed. Underleaves contiguous to distant, 200−230 µm long × 190−280 µm wide, ca. 2.0−3.0× stem width, ovate to suborbicular, bifid to 1/2, lobes triangular, sinus V-shaped, bases cuneate, insertion line slightly curved. Autoicous. Androecia terminal in the main stem or intercalary, or on short to long lateral branches, 3−4 pairs of bracts, bracteoles present throughout the spike. Gynoecia on short or long lateral branches, or on the main stems, without innovations, occasionally with one subgynoecial branch Lejeunea - type (pseudo-innovation), bract lobes obovate, margins entire, apices rounded, 550 µm long × 380 µm wide, bract lobules oblong, apices acute, 480 µm long × 130 µm wide, bracteoles oblong, bifid, margins entire; perianths obovoid, 610 µm long, 480 µm in diameter, 4-keeled, keels smooth to crenulate, beak long, 110 µm long × 50 µm wide, 3−4 elongated cells high.

Etymology:—In reference to the type locality (Praia da Lua): a white sands beach along the Rio Negro near Manaus.

Distribution and habitat:—Restricted to the State of Amazonas, Northern Brazil. The holotype was collected on the base of trees in a seasonally inundated forest on a fluvial island of the Rio Negro near the Praia da Lua ~ 20 km from Manaus. However, other specimens were collected near São Gabriel in terra firme forest and in Serra do Aracá.

Notes:—The new species resembles the neotropical Cheilolejeunea aneogyna , but differs from the latter by the following characters: (1) leaf lobe margins formed by two rows of quadrate cells; (2) androecial branches with bracteoles present throughout the spike (bracteoles only at base of the spike in C. aneogyna ); (3) large, subrectangular leaf lobules (160−230 µm long × 95−115 µm wide), ca. 1/2−2/3 leaf lobe length (leaf lobule shorter, triangular-ovate to subrectangular, 100−140 µm long × 80−92 µm wide, ca. 1/3 of the lobe length in C. aneogyna ); (4) leaf lobe cells strongly mammillose (cells weakly mammillose in C. aneogyna ) (5) ventral merophyte 2−3 cells wide (only two cells wide in C. aneogyna ).

Asexual reproduction by caducous leaves, sometimes with rhizoids on the margin, was reported for C. aneogyna by Gradstein & Costa (2003) and Bastos (2008, 2012). This characteristic has not yet been observed in the specimens of C. luensis studied.

An interesting characteristic of C. aneogyna , also shared with C. luensis , is the greater development of the first tooth of the leaf lobule in relation to the reduced second tooth. This is unusual in Cheilolejeunea . Mizutani (1961), Bastos (2010) and Renner (2012) stated that the genus Cheilolejeunea is diagnosed not by the position of the hyaline papilla (this is always positioned at the proximal base of the first tooth and, consequently, distal to the second tooth), but rather by the greater development of the second tooth, in relation to the first tooth, which is reduced. Specimens of section Trachylejeunea with a more developed first tooth could be confused with species belonging to the genus Pycnolejeunea (Spruce 1884: 246) Schiffner (1893: 124) , especially due to the greater development of the first tooth and the strongly mammillose cells of the leaf lobe, since the absence of ocelli would not be unusual in Pycnolejeunea (some specimens of C. aneogyna were found with ocelli, as reported by Bastos 2012).

Additional specimens examined:— BRAZIL. Amazonas : Between Manaus and São Gabriel , along Rio Curicuriari near mouth of the Rio Cariua ; terra firme; 00°20’S, 66°55’W, 14 July 1979, R. M. Schuster 79-17-880 ( F) GoogleMaps ; Barcelos , Serra do Aracá , Rio Aracá, Igarapé Madixi, 0°14’29”S, 63°06’03”W, 18 August 2014, C. E. Zartman 9613 ( INPA / ALCB) GoogleMaps .

Cheilolejeunea remotistipula (C.J. Bastos & C.E. Zartman) A.M. Sierra, C.J. Bastos & C.E. Zartman , comb. nov. Basionym: Pycnolejeunea remotistipula C.J. Bastos & C.E. Zartman, Neodiversity View in CoL 10: 2. 2017. Type:― BRAZIL. Amazonas: Rio Negro,

between Manaus and São Gabriel, along BR 307, from São Gabriel, just N of igarapé-Mirim, near Jerusalém; primary forest,

00°20’N, 66°35’W, 17 July 1979, R. M. Schuster 79-18-835 ( holotype, F!). Description and illustration: Bastos & Zartman (2017).

Notes:―The Cheilolejeunea remotistipula was previously described as Pycnolejeunea remotistipula Bastos & Zartman (2017: 2) by Bastos & Zartman (2017) because the first tooth of the leaf lobule is well developed, and the second tooth is reduced. However, this possibility (the first tooth being elaborated in relation to the second tooth) was observed in some Cheilolejeunea species belonging to sect. Trachylejeunea , as observed in Cheilolejeunea aneogyna , for example. More detailed studies of the holotype of P. remotistipula , mainly in relation to the morphology of the leaf lobule, as well as the absence of innovation showed that P. remotistipula is a member of Cheilolejeunea Sect. Trachylejeunea .

Due to the long, subrectangular leaf lobule and lack of innovations, C. remotistipula also resembles the new species described here, C. luensis . However, the new species can be separated from C. remotistipula based on the following characteristics: (a) perianth with long beak (shorter to very short in C. remotistipula ); (b) androecial branches with bracteoles present throughout the spike (bracteoles only at base of the spike in C. remotistipula ); (c) free margins of the leaf lobule 8−10 cells long (15−17 cells long in C. remotistipula ); and (d) underleaves with acute lobe apices (rounded to obtuse in C. remotistipula ). In Cheilolejeunea luensis sp. nov. often the first tooth is more developed (as is also common in C. aneogyna ), and this tooth may be straight or vertically oriented, as is observed in C. remotistipula . In this condition the two species can be confused, and only careful examination of the four characters listed above can ensure correct identification of the specimens.

Additional specimens examined:— BRAZIL. Amazonas: São Gabriel da Cachoeira, Rio Negro, Ilha Cariuari, 20 km descendo o Rio desde a cidade de São Gabriel da Cachoeira, 0°10’47.5”S 67°01’25.0”W, floresta sazonalmente inundada (Igapó), epífita, 16 December 2016, A. M. Sierra & C. E. Zartman 4702 ( INPA).