New additions to leafy liverwort fl ora ( Marchatiophyta , Jungermanniopsida ) of Sri Lanka

Leafy liverworts (Marchantiophyta, Jungermanniopsida) comprise a morphologically diverse and complex group of liverworts. Based on past checklists and publications, 25 families, 62 genera and 290 species of leafy liverworts are known to occur in Sri Lanka. The existing checklists largely depend on old publications, and lack proper taxonomic descriptions, keys and locality details, hampering further research and conservation of this important group of plants. A detailed taxonomic survey was initiated to explore and document the leafy liverwort flora of Sri Lanka. Fresh samples were collected and surveyed for morphological, anatomical and spore morphological characters. Specimens were identified using the unique characters based on recent taxonomic keys and monographs and authenticated using type specimens and/or descriptions. Six new species were identified as new records to Sri Lanka: Lejeunea sordida (Nees) Nees, Leptolejeunea subdentata Schiffn., Spruceanthus polymorphus (Sande Lac.) Verd., Frullania udarii Nath et Singh, Heteroscyphus turgidus (Schiffn.) Schiffn. and Fuscocephaloziopsis lunulifolia (Dumort.) Vaňa et L.Soderstr. The genus Fuscocephaloziopsis Fulford is recorded as a new genus to Sri Lanka. Taxonomic descriptions along with photo plates are provided for all the species reported. Addition of the six new records increases the total number of leafy liverwort species of Sri Lanka from 290 to 296 and the number of genera from 62 to 63.


INTRODUCTION
The tropical island of Sri Lanka covering only a total land area of about 656,110 km 2 harbours a rich diversity of fl ora and fauna owing to its varied climate and topography (Gunawardene et al., 2007;Long & Rubasinghe, 2014). According to Myers et al. (2000) 1.6 % of the global plant species and 3.9 % of the global animal species are recorded in Sri Lanka and about half of both plants and animals are endemic to the island. However, bryophyte fl ora (liverworts, mosses, hornworts) of the island remains poorly researched. Among the bryophytes, leafy liverworts (Marchantiophyta, Jungermanniopsida) are one of the least studied. Yet, leafy liverworts comprise one of the most diverse and complex groups among bryophytes and include about 4500 species worldwide (Heinrichs et al., 2007). According to the latest checklist, 25 families, 62 genera and 290 species of leafy liverworts are known to occur in Sri Lanka (Long & Rubasinghe, 2014). Apart from the 03 new additions made by Samarakkody et al. (2018) no taxonomic surveys are being carried out on Sri Lankan leafy liverworts. The existing checklists are largely based on previously published old literature rather than actual specimens. Therefore, taxonomic descriptions, keys or illustrations for most of the recorded species are lacking.

June 2020
Journal of the National Science Foundation of Sri Lanka 48 (2) Lack of locality details or phenological data hampers the conservation of leafy liverworts within the island. Therefore, to fulfi ll this timely requirement, a detailed taxonomic survey was carried out to explore the diversity of leafy liverworts in Sri Lanka.

METHODOLOGY
Field excursions were carried out throughout the country to collect fresh samples of leafy liverworts. The collected samples were thoroughly surveyed for morphological and anatomical characters using light (Hertel and Reuss, Optik Kassel, Germany), binocular (Olympus CX21, Philippines) and trinocular (Zeiss, Primo Star, Germany) microscopes. Cellular measurements were obtained using a binocular microscope (Zeiss, Primo Star, Germany). Characters were recorded for each specimen collected. The specimens were identifi ed using recent taxonomic keys, descriptions and monographs based on the most recent classifi cation by Crandall-Stotler et al. (2009). Identifi ed species were authenticated using type descriptions. Herbarium specimens were prepared using Schofi eld (1985) method, and voucher specimens were deposited at the National Herbarium, Peradeniya (PDA). Note: Dioicous. Androecia terminal on short or long branches, with closely imbricate bracts; bracts in pairs, lobule strongly infl ated; bracteole smaller than the under leaf. Gynoecia terminal on short branch, with loosely arranged bracts with one innovation, usually with 1 -2 gynoecia in a lateral row; bracts slightly larger than the leaf, bracts and bracteoles in 2 series; lobe ovate, apex obtuse, margin entire; lobule lanceolate, apex obtuse. Perianth obovate, with 5-keels and 2 -3 cells long beak, base straight, stalk-like elongation absent (Lee, 2020).

RESULTS AND DISCUSSION
Habitat: Found growing on tree trunks and rarely on leaves of trees. Commonly found in lowland rain forests.
Habitat: An epiphyllous leafy liverwort found in low land rain forest.
Habitat: Found on tree barks and branches in rain forests.
Distribution: The species is reported from Indopacifi c region (Wang et al., 2016).
Remarks: Important characters of S. p olymorphus that can be used to separate the species from other similar species include: robust nature of the plant; dimorphic diff erentiation of gynoecial and vegetative branches (leaves and underleaves of vegetative branches have plane and entire margins but those in gynoecial branches are toothed and with undulate ventral margin); large leaf trigones; large and toothed female bracteoles (Thiers & Gradstein 1989;Gradstein, 2002;Wang et al., 2016). Spruceanthus poly morphus and S. p laniusculus are morphologically closely related. However, the size of S. planiusculus is smaller than S. polymorphus and also S. planiusculus does not have microphyllous branches, and vegetative and gynoecial shoots are not morphologically diff erent (Wang et al., 2016;Gradstein, 2002). notch. Leaf lobes narrowly connected with each other dorsally, slightly broader than long or almost rounded, 1.8-2.5 mm long, 2-3 mm wide, slightly convex. Leaf cells isodiametric, sub-rounded, trigones large, knot-like, marginal cells 10-24 µm long, 10-20 µm wide, median cells 14-35 µm long, 12-28 µm wide, basal cells same as median cells. Underleaves connected with lateral leaves, almost rounded, broader than long, apex shallowly 2-lobed, 1.0-1.8 mm long, 1-2 mm wide, margins with several teeth. Rhizoids at base of underleaves or scattered on ventral side of stem, numerous, fasciculate. Plants dioicous. Perianth large, mouth lobed, lobes lanceolate to ovate. Perichaetial leaves ovate, 2-lobed, irregularly toothed. Sporophyte not seen. Habitat: On trunks of trees in low land rain and sub montane forests.
Distribution: The species is also reported from China (Taiwan), Indonesia (Sumatra) and Papua New Guinea (Gao et al., 2004).
Remarks: Five species are recorded under the genus Heteroscyphus, from Sri Lanka (Long & Rubaisnghe, 2014). The species can be easily identifi ed from other species of the genus by the medium to large plants with olive green colour, glossy appearance of fresh plants, slightly convex leaves, leaf cells with very large trigones (Gao et al., 2004).   Habitat: Frequently found on tea stem barks of tea plantations in montane zone.
Distribution: The species is reported as endemic to India (Nath & Singh, 2006). This is the fi rst record of the species from outside of India.
Habitat: Found on wet soil of roadsides and on rocks and soil in montane forests.

Remarks:
The genus Fuscocephaloziopsis Fulford is newly reported from Sri Lanka. Twenty seven species are recorded under the genus (Söderström et al., 2016). Fuscocephaloziopsis lunulifolia is morphologically closely related to F. loitlesbergeri (Schiff n.) Váňa et L. Söderstr. However, F. lunulifolia can be easily distinguished by the yellowish green plants, leaf lobes ending in a row of 1-2 cells and perianth mouth with 1(2) celled teeth. In F. loitlesbergeri plants are brownish in colour, leaf lobes end in a row of 2-3 cells and perianth mouth has 2-6 celled cilia (Casas et al., 2009;Potemkin & Sofronova, 2013).