According to Schwendener[434] development begins by an exuberant growth of the medulla which raises and finally bursts the cortex; prominent cyphellae have been thus formed in Sticta damaecornis ([Fig. 73]). In other species the swelling is less noticeable or entirely absent. The opening of the cup measures usually about 1/2 mm. across, but it may stretch to a greater width.
c. Pseudocyphellae. In these no margin is formed, the cortex is simply burst by the protruding filaments which are of the same colour—yellow or white—as the medullary hyphae. They vary in size, from a minute point up to 4 mm. in diameter.
d. Occurrence and Distribution. The genus Sticta is divided into two sections: (1) Eusticta in which the gonidia are bright-green algae, and (2) Stictina in which they are blue-green. Cyphellae and pseudocyphellae are fairly evenly distributed between the sections; they never occur together. Stizenberger[435] found that 36 species of the section Eusticta were cyphellate, while in 43 species pseudocyphellae were formed. In the section Stictina there were 38 of the former and only 31 of the latter type. Both sections of the genus are widely distributed in all countries, but they are most abundant south of the equator, reaching their highest development in Australia and New Zealand.
In the British Isles Sticta is rather poorly represented as follows:
§ Eusticta (with bright-green gonidia).
Cyphellate: S. damaecornis.
Pseudocyphellate: S. aurata.
§ Stictina (with blue-green gonidia).
Cyphellate: S. fuliginosa, S. limbata, S. sylvatica, S. Dufourei.
Pseudocyphellate: S. intricata var. Thouarsii, S. crocata.