Cheilolejeunea amazonica C. Bastos & C. E. Zartman, 2016

Bastos, Cid José Passos & Zartman, Charles E., 2016, Cheilolejeunea amazonica (Lejeuneaceae, Marchantiophyta), a new tepui species from northern Brazil, Phytotaxa 266 (1), pp. 15-20 : 15-17

Cheilolejeunea amazonica C. Bastos & C. E. Zartman , sp. nov. ( Figures 2‒7 )

Similar to Cheilolejeunea ornata , but differing by its triangular-ovate leaf lobes, straight dorsal margin, large, spreading lobules which reach greater than 1/3 the length of the leaf lobe, oblong second lobule tooth, 4 medullary cells in stem cross section and a rounded and truncate underleaf lobe apex.

Type :— BRAZIL: Amazonas , Barcelos , Rio Aracá, summit of Serra Aracá, 0°52’04”N, 63°19’56”W, elev. 1300 m, on rocks along stream 1 km southeast from the top of Arará (El Dorado) waterfall, 18 August 2014, C. E. Zartman 9667 (holotype ALCB; isotype NY). ( Figure 1 ) .

Plants growing in straggling mats, gametophytes small, 400–560 μm wide, vegetative branches Lejeunea - type. Stem 50 μm diameter, in cross-section 7 cortical cells and 4 medullary cells, thick walls. Ventral merophyte two cells wide. Leaves imbricate, spreading, slightly ascending; lobes triangular-ovate, 200–300 μm long × 150–200 μm wide, dorsal margin straight or slightly arched, strongly crenulate, ventral margin slightly arched, generally curved, apex sharp, curved; cells oblong and hexagonal, 25–40 μm long × 15–18 μm wide, thick walls, strongly papillose dorsally, papillae large, 10–13 μm long × 13–15 μm wide at base, trigones very large, intermediate thickenings occasional; oil bodies not observed; ocelli absent; lobule spreading, ovate-elongated, reaching 1/3 or more the length of the leaf lobe, apex characteristically curved inward, 150–200 μm long × 80–100 μm wide, free margin strongly involute, second tooth unicellular, short, acute, totally hidden by the free margin, apical margin circular, keel arched, strongly papillose. Underleaves small oblong to obovate, 130–180 μm long × 110–130 μm wide, sinus acute, ca. 1/3 the length of the underleaf, lobe apices rounded to truncate, slightly divergent or straight, base cuneate, insertion line slightly curved. Androecium and gynoecium not found.

Etymology: In reference to the Amazon, an important area of endemism for leafy liverworts.

Distribution: Super humid vertical sandstone rock faces and spray cliffs along streams draining the northern flanks of the Serra do Aracá ( Figure 1 ). This species is known only from the type locality, it has not been collected in other areas or environments. Of all Cheilolejeunea occurring in Brazil, 10 are considered endemic to the country (Bastos in prep.), in which four main areas of endemism are recognized in Brazil: Amazonas (northern Brazil), São Paulo (southeast Brazil), Minas Gerais (Southeast Brazil) and Bahia (northeast Brazil). Some Brazilian taxa, such as Cheilolejeunea asperiflora ( Spruce 1884: 183) Gradstein & Ilkiu-Borges (2009: 62) , Cheilolejeunea neblinensis Ilkiu-Borges & Gradstein (2008: 522) , Cheilolejeunea polystachya ( Spruce 1884: 250) Gradstein & Ilkiu-Borges (2009: 62) and Cheilolejeunea riparia ( Spruce 1884: 251) Reiner-Drehwald (2012: 467) , are apparently restricted to the Amazon region. The discovery of this species reinforces the Amazon region as one of the major areas of endemism for the genus Cheilolejeunea in Brazil, and highlights the importance of conducting floristic inventories especially in montane regions of northern South America.

Figures

FIGURE 1. Photograph showing the collection site, Rio Aracá, summit of Serra Aracá, rocks along stream (Photo by C. E. Zartman).

FIGURES 2‒7. Cheilolejeunea amazonica. 2: Portion of gametophyte, ventral view. 3: Portion of gametophyte with underleaf and leaf lobule. 4: Underleaf. 5: Apical tooth lobule. 6: Laminal cells. 7: Stem in cross section with remains of leaves and large papillae on dorsal leaf side. (from holotype, C.E. Zartman 9667).