1	Thallus ribbon-like; shoots at the sinuses of the thallus or along the margins of the thallus	2
–	Thallus crustose; shoots scattered on the dorsal surface of the thallus	5
2	Flowers sessile; spathella apex round; capsule smooth	Z. sessile
–	Flowers pedicellate; spathella apex acute or obtuse; capsules ribbed	3
3	Shoots present along the margins and sinuses of the thallus; bracts 2 per floriferous shoot; spathella apex obtuse; stigmatic lobes unequal; capsules ellipsoidal	Z. manasiae
–	Shoots restricted to the sinuses of thallus; bracts 4–6 per floriferous shoot; spathella apex acute; stigmatic lobes equal; capsules globose	4
4	Spathella apex papillate; ovary 2-locular	Z. lichenoides
–	Spathella apex smooth; ovary 1-locular	Z. tailichenoides
5	Shoots dimorphic; primary shoot with a tuft of over 20 leaves; secondary shoots with 4–6 leaves	Z. olivaceum
–	Shoots monomorphic with 4–6 leaves	6
6	Leaves up to 10 cm long; bracts 3–4; gynophore absent	Z. johnsonii
–	Leaves 3–5 mm long; bracts more than 4; gynophore present	7
7	Bracts 4–6; stigma bilobed; capsules 8-ribbed	Z. crustaceum
–	Bracts 6–8; stigma multilobed; capsules 6-ribbed	Z. maheshwarii