NEW OR LITTLE-KNOWN EPIPHYLLOUS LIVERWORTS, XXIV. A COLLECTION MADE IN THE VENEZUELAN GUAYANA AT THE FOOT OF SALTO ANGEL WITH DESCRIPTION OF COLOLEJEUNEA BENCEI

A liverwort collection by Bence Pócs from the Venezuelan Guayana resulted in 31 species of liverworts, including Cololejeunea bencei new to science and C. cardiocarpa , C. obliqua , C. platyneura , C. schusteri , C. verwimpii , Lejeunea pulchra and Plagiochila crispabilis new to Venezuela. The distribution and differentiation of C. schusteri is discussed. and


INTRODUCTION
During the October of 2001 my son Bence Pócs made a major trip on the tepuis of the Venezuelan Guayana. He made collections of mostly epiphyllous liverworts at my request close to Angel Falls (Salto Angel) in the foothills of Auyán-tepui. As a result, he collected 32 species of liverworts and 2 species of mosses. From the collection a strange looking Cololejeunea species turned to be new to science and further 7 liverwort species were new to Venezuela.
The locality of the specimens, unless indicated otherwise, is: Bolivar state, Municipio Gran Sabana, foothills of Auyán-tepui SW of Canaima, at a ridge E of Rio Churún valley and Angel Falls (Salto Angel), on the way to viewpoint Mirador Laime, between 600 and 1,000 m elevation, in wet submontane rainforest, coll. B. Pócs (01161), 31 October 2001. I added a few records of the enumerated species from other collections; in the latter case their localities are given. All specimens were identified by the author and deposited in the herbarium of Eszterházy Károly University, Eger, Hungary (EGR).

DESCRIPTION OF THE NEW SPECIES
Cololejeunea bencei Pócs, spec. nova (Fig.  Description: Plants in herbarium pale brown, forming scattered colonies of 3-12 mm diameter on living dicotyledonous leaves. Shoots 0.8-0.95 mm wide. Stems up to 5 mm length, 30-60 µm thick, with 1 ventral merophyte. Cross section terete with 5-6 rows of cortical and 1 row of medullary cells. Rhizoids forming about 150 µm wide rosettes near each leaf base, colourless, 10-12 µm wide, at their end often bifurcate. Leaves broad ovate, somewhat asymmetric, falcate, 5-600 × 280-400 µm, ventral lobe margin forms an angle of 70-90° to the stem. Lobe apex acuminate or sometimes obtuse, margin entire and often with one interrupted row of hyaline border with rectangular or irregular shaped dead cells. Basal lobe cells 24-38 × 10-20, median 20-30 × 16-22, apical 10-20 × 7-12 µm, with moderately incrassate walls, small trigones and on part of them with 1-2 intermediate thickenings. About on 25% of the cells bear round papillae on their dorsal wall. The hyaline border cells with very thin walls without thickenings. Lobule inflate, ovate, 30-40% of lobe length, 50-80 × 25-50 µm, at its base with a larger socle cell. Median cells isodiametric or slightly rectangular with moderately thickened walls, very small trigones, without intermediate thickenings and papillae. First tooth 1-2 celled with a hyaline papilla on its ental side. Second tooth obsolete or completely missing. The keel joins the postical lobe margin with a very wide angle or continuous.
Autoicous. Antheridia on short side branches or at shoot apex, up to 600 µm length and 300 µm width. They consist of 4-8 pairs of male bracts, each up to 200 µm, ovate-lanceolate with acuminate apex sometimes tipped by 1-2 hyaline cells. Their lobule about half length of the lobe. Archegonia on the side or apex of shoot or branches, with one innovation. Female bracts cuneiform, usually with hyaline apex, reaching 3/4 length of the mature perianth, with lobule about 30% of lobe length. Perianth obpyriform, 600 × 400-450 µm, with moderately compressed side wings and a strongly inflated ventral segment. Perianth wall formed by 20-25 µm isodiametric cells with moderately thickened walls. Perianth apex umbilicate with a pore without beak, surrounded star-like with border cells of incrassate wall, in the near horizontal plane of perianth apex, similarly to the atming pores of Marchantiales. Sporophyte and vegetative ways of reproduction are unknown.
The new species seems to be endemic to the Venezuelan Guayana. By the acuminate leaf lobe tipped by hyaline cells the new species is similar to the neotropical Cololejeunea ecuadoriensis Pócs and C. minutilobula Herzog, but C. ecuadoriensis Pócs lacks styli and C. minutilobula Herzog has a very different lobule.

ENUMERATION OF THE OTHER COLLECTED SPECIES
Almost all species cited below were epiphyllous and collected at the same locality as the new species; two were corticolous (see text). Nomenclature follows Söderström et al. (2016). Synonyms are cited for recently changed names. General distribution is given in detail, with references for less common species. Records new to Venezuela (marked by asterisk) are based on Dauphin et al. (2008) and Morales et al. (2007).

Drepanolejeunea biocellata A. Evans -No 01161/X -A widely distributed neotropical species from Mexico to Bolivia and Brazil.
Drepanolejeunea crucianella (Tayl.) A. Evans -No 01161/Y -This tiny liverwort, especially its small form earlier called D. trifida Steph., covered large portions of the collected leaves. It is common from the Caribbean islands to Brazil.
*Lejeunea pulchra C. J. Bastos et Gradst. -No 01161/AB ( Fig. 3B-C) -This tiny species is hitherto known only from the type described from the state of Bahia, Brazil (Bastos and Gradstein 2020). It is well characteristised by the leaves directed forward, imitating a Microlejeunea, its papillose cuticle, strongly inflated lobuli with small, curved tooth and relatively wide underleaf lobes.
Lepidozia cupressina (Sw.) Lindenb. -No 01161/AD, collected from tree bark. -A bipolar temperate species widespread also in tropical American and African mountains .
*Plagiochila crispabilis Lindenb. (Syn.: P. patentissima Lindenb.) -No 01161/ AG (Fig. 3D), collected from tree bark. -A species common in eastern Brazil, not yet known elsewhere Costa 2003, Gradstein 2021). Its occurrence in the Venezuelan Guayana is a meaningful extension of its known distribution area. Its distinguishing characters are the terminal branching and the rectangular leaves with parallel, almost straight margins without border (Gradstein 2016(Gradstein , 2021.

DISCUSSION
The relatively high number of epiphyllous species on the rather few living leaves collected (ca. 0) is indicative of favourable microclimatic habitat conditions. The species composition of the collected epiphylls is presumably characteristic of the tepui foothills in the Venezuelan Guayana, in view of the common presence of Amazonian and Brazilian species, like Cheilolejeunea lineata, Cololejeunea schusteri, Lejeunea pulchra and Plagiochila crispabilis. The high number of species new to the country (1/4 of all collected species) shows the still inadequate knowledge of the bryoflora of the Venezuelan Guayana, in spite of numerous collections made at higher altitudes on the tepuis by Steyermark (Fulford 1967, Morales et al. 2007.
A group of species related to the worldwide distributed Cololejeunea cardiocarpa seems to have evolved in the Neotropics, many more than in other continents. These include C. ecuadoriensis, C. microandroecia, C. minutilobula, C. schusteri, C. subcardiocarpa and C. verwimpii. A molecular taxonomic study should be carried out on this interesting species complex. The taxonomic position of the C. schusteri-like population of C. cardiocarpa on the Galápagos Islands also needs further work.