2. Calasterella D.G.Long & T.X.Zheng, gen. nov.

Type species: Calasterella californica (Hampe ex Austin) D.G.Long & T.X.Zheng comb. nov. (≡ Fimbraria californica Hampe ex Austin, Hepat. bor.-amer. 33, 1873).

Fig. 1, 2, 3

Description: Dioicous; thallus lacking odour when crushed, branching strictly dichotomous, differentiated into upper photosynthetic aerenchyma with irregular air chambers in up to 5 layers and ventral compact tissue with mucilage cavities, epidermis with simple air pores; ventral scales in two rows, each with 1–4 subulate appendages; gemma cups absent; rhizoids dimorphic; androecium cushioned, dorsal, not terminating vegetative growth; female receptacle ovoid, deeply 4(5)-lobed, with stout, longitudinally ridged stalk, terminal on main thallus, not terminating vegetative growth which continues as innovations from both apical lobes; involucre deeply cleft to base, sporophyte enclosed in pseudoperianth; spores lemon-yellow with conspicuous trilete ridges, prominent equatorial wing, similar ornamentation on proximal and distal surfaces, lacking large areolae but with fine network of alveolae.

Etymology: The genus is named by the combination of the abbreviation of its main distribution region “ California ”, and the previous placement “ Asterella ”.

Distribution: North America (Mexico and United States).