[1] It has a dull yellowish-white to light brown and reddish-brown thallus and is typically 3–5 cm (1.2–2.0 in) long.

It is only known to occur in the Los Osos Oaks State Natural Reserve, in the Central Coast of California region, where it grows on a variety of shrubs.

The type specimen was collected in 1984 from Los Osos Oaks State Natural Reserve, in the Central Coast of California region; it was growing on Adenostoma fasciculatum.

[3] Sulcaria isidiifera is characterized by a thallus that is a dull yellowish-white, transitioning into light brown and reddish-brown at the more sun-exposed tips, and occasionally displaying shades of olive-gray.

[3] Sulcaria isidiifera is exclusively found near its original discovery site, confined within a region less than 7 mi (11 km) in diameter.