simple thalloid liverworts, Stotler & Crand.

Ruklani, Sumudu & Rubasinghe, Sumudu C. K., 2022, Thalloid Liverworts (Marchantiopsida) of Sri Lanka, Phytotaxa 551 (1), pp. 1-82 : 55-56

Key to families of simple thalloid liverworts in Sri Lanka

1. Plants with stem and leaves................................................................................................................................................................2

- Plants thalloid .....................................................................................................................................................................................3

2. Plants robust, reddish or purplish. Leaves deeply clasping the stem, undivided ......................................................... Pleuroziaceae

- Plants pale green, green or yellowish green, usually forming rosettes. Leaves succubously inserted to the stem .............................. .............................................................................................................................................................................. Fossombroniaceae

3. Thallus simple or pinnate, without midrib or with midrib only on branches. Gametangia on the thallus margin or on short lateral branches........................................................................................................................................................................... Aneuraceae

- Thallus simple or dichotomous, with a midrib throughout. Gametangia on the midrib on dorsal or ventral side ............................4

4. Thallus usually 2–3 mm wide, margins with unicellular hairs or rhizoids. Midrib without central strand in cross section. Gametangia on the ventral side of the midrib.................................................................................................................................. Metzgeriaceae

- Thallus usually more than 3 mm wide, margins without hairs. Midrib with central strand. Gametangia on the dorsal side of the midrib ....................................................................................................................................................................... Pallaviciniaceae

Key to the genera of simple thalloid liverworts of Sri Lanka

1. Plants thalloid .....................................................................................................................................................................................2

- Plants leafy .........................................................................................................................................................................................6

2. Thallus with a mid-rib, archegonia and antheridia on dorsal or ventral side of the midrib ...............................................................3

- Thallus mid-rib lacking or indistinct, archegonia and antheridia at thallus margin ..........................................................................5

3. Plants dendroid, thallus margin sharply toothed, thallus growing erect from a creeping rhizome ....................................... Jensenia

- Plants not dendroid; thallus margin entire or with hairs, not sharply toothed, thallus creeping/erect, rhizome lacking....................4

4. Thallus more than 3 mm wide, with undulate wings, without hairs; antheridia in rows on midrib; archegonia aligned on midrib.... .......................................................................................................................................................................................... Pallavicinia

- Thallus less than 3 mm wide, without undulate wings, with scarce hairs at margins or on ventral side; antheridia on ventral side of midrib; archegonia on ventral side of thallus ..................................................................................................................... Metzgeria

5. Thallus more than 3 mm wide, fleshy, irregularly branched, shortly stalked, multicellular; more than 6 oil-bodies in each epidermal cell; gemmae exogenous, shortly stalked, multicellular and bulbous ..................................................................................... Aneura

- Thallus less than 3 mm wide, pinnately branched or palmate; 0–2 oil-bodies in each epidermal cell; gemmae endogenous, formed within the walls of existing cells, 1–2 celled, at the thallus apex......................................................................................... Riccardia

6. Plants green, to light green with two rows of lateral thallus lobes which are leaf-like; slime papillae present as ventral appendages or present on leaves; antheridia scattered along stem; mostly bright orange to yellow in colour; archegonia naked and dispersed dorsally on the stem; capsules spheroidal .................................................................................................................... Fossombronia

- Plants reddish rarely green with succubous, complicatedly bilobed leaves; slime papillae lacking; antheridia solitary in the axils of reduced perigonial leaves; archegonia enclosed by a perianth; capsules ovoid to subspheroidal........................................ Pleurozia