complex thalloid liverworts, Doweld

Ruklani, Sumudu & Rubasinghe, Sumudu C. K., 2022, Thalloid Liverworts (Marchantiopsida) of Sri Lanka, Phytotaxa 551 (1), pp. 1-82 : 14-15

Key to the families of sterile complex thalloid liverworts of Sri Lanka

1. Thallus well differentiated into layers with air chambers ..................................................................................................................2

- Thallus weakly differentiated into layers without distinct air chambers.................................................................. Dumortieraceae

2. Thallus with compound air pores in the epidermis, gemmae present cupules cup-shaped..................................... Marchantiaceae

- Thallus with simple air pores in the epidermis, gemmae absent or present, cupules not cup-shaped ...............................................3

3. Gemmae present in crescent-shaped cupulues ............................................................................................................ Lunulariaceae

- Gemmae absent ..................................................................................................................................................................................4

4. Thallus very thin, 2-layered, translucent ..................................................................................................................... Cyathodiaceae

- Thallus thick, several layered, not translucent ...................................................................................................................................5

5. Air chambers with chlorophyllose filaments......................................................................................................................................6

- Air chambers without chlorophyllose filaments.................................................................................................................................7

6. Thallus green with purplish pigmentation ................................................................................................................... Targioniaceae

- Thallus green, without purplish pigmentation .......................................................................................................... Exormotheceae

7. Ventral scales in 2 or several rows, appendages absent ..................................................................................................... Ricciaceae

- Ventral scales in 2 rows, with 1–4 appendages ............................................................................................................... Aytoniaceae

Key to families of fertile complex thalloid liverworts of Sri Lanka

1. Perigonial chambers on stalked receptacles .......................................................................................................................................2

- Perigonial chambers aggregated in cushions or embedded in groups on dorsal surface of thallus or on short branches ..................3

2. Perigonial receptacles bearing compound air pores, stalk with 2 to 4 rhizoid furrows; involucre bivalved or cup-shaped; pseudoperianths present............................................................................................................................................ Marchantiaceae

- Perigonial receptacles bearing few open-air chambers, stalk with 2 rhizoid furrows; involucres tubular, bristly, opening by a slit; pseudoperianths absent............................................................................................................................................. Dumortieraceae

3. Sporophyte on stalked receptacles .....................................................................................................................................................4

- Sporophytes lacking receptacles.........................................................................................................................................................5

4. Perigonial chambers aggregated in terminal cushions on thallus; seta massive, elongating prior to spore dispersal.......................... ..................................................................................................................................................................................... Lunulariaceae

- Perigonial chambers embedded in dorsal groove of thallus or in irregular rows on thallus; seta remaining short............................6

5. Sporophytes embedded singly in the thallus; involucres absent; seta absent; elaters absent; capsules cleistocarpous ..... Ricciaceae

- Sporophytes ventral at the thallus apex; involucres bivalved; seta remaining short; elaters few per capsule; capsule dehiscence by a lid and irregular valves ....................................................................................................................................................................7

6. Receptacles bearing compound air pores; involucres bivalved, cup-shaped or flap-like; capsule dehiscence by a lid ....................... ......................................................................................................................................................................................... Aytoniaceae

- Receptacles bearing simple air pores, stalk with 1 rhizoid furrow; involucres tubular; capsule dehiscence by irregular valves or irregular lid and valves .......................................................................................................................................... Exormothecaceae

7. Thallus thicker (more than 2 layers), not translucent; antheridia borne on special branches; sporophyte in a dark, swollen, mussellike bivalved involucre below the thallus apex foot and seta of sporophyte well developed ...................................... Targioniaceae

- Thallus very thin, 2-layered, translucent; antheridia scattered in clusters along the edge of the thallus; sporophyte in an apical notch on the ventral thallus surface; foot and seta of sporophyte represented by a single filament ..................................... Cyathodiaceae

Key to the genera of Complex Thalloid liverworts of Sri Lanka

1. Thallus with cupules.......................................................................................................................................................................... 2

- Thallus without cupules......................................................................................................................................................................3

2. Gemma-receptacles cup-shaped; dorsal epidermis with compound pores....................................................................... Marchantia

- Gemma-receptacles crescent-shaped; dorsal epidermis with simple pores......................................................................... Lunularia

3. Photosynthetic tissue with narrow, vertical, channel-like air chambers or air chambers vestigial ....................................................4

- Photosynthetic tissue with air-chambers in one or more layers .........................................................................................................5

4. Air chambers absent, thallus weakly differentiated into layers........................................................................................ Dumortiera

- Air chambers in more than one layer or channel-like, thallus well differentiated into layers................................................... Riccia

5. Thallus very thin, 2-layered, translucent ......................................................................................................................... Cyathodium

- Thallus thick, several layered.............................................................................................................................................................6

6. Ventral scales hyaline, without appendages .................................................................................................................. Exormotheca

- Ventral scales purplish, with appendages ...........................................................................................................................................7

7. Ventral scales with 1 appendage; sporophytes ventral at the thallus apex ........................................................................... Targionia

- Ventral scales with 1 to 4 appendages; sporophytes on stalked receptacles.......................................................................................8

8. Ventral scales with ovate to lanceolate appendages; appendages purplish pink to hyaline, not constricted at base............................ ...................................................................................................................................................................................... Plagiochasma

- Ventral scales with 2 or 3 filiform appendages ..................................................................................................................... Reboulia