AUSTRALIA. Australian Capital Territory, Solar Village, J.A. Elix 39805 (holotype: CANB 783260).

Similar to Neoprotoparmeliaisidiata, but differs from it in having shorter isidia and a thicker thallus.

Derived from crassus (Lat. = fat) indicating that the thallus is thicker than that of the other isidiate species.

Thallus consisting of contiguous to centrally fusing, flat to rather convex areoles with irregular shape, of up to ca. 0.1 mm thick and 0.3 mm wide, somewhat shiny, pale brown to dark brown, marginal prothallus absent. Isidia covering most of the thallus except the outer margins, globose to ellipsoid, up to 0.15 mm long, persistently 0.07–0.1 mm wide, unbranched, of thallus colour, tips not darkened or somewhat brown. Apothecia and pycnidia not observed.

Spot tests: medulla of thallus and isidia UV+ greenish white, C–, P–, K–, KC+ pink. TLC: alectoronic acid.

On wood or bark of trees in open or closed forests. Known only from Australia (Australian Capital Territory and Northern Territory).

(specimen: Elix 39805, holotype: CANB 783260). KP822464 (mtSSU), KP822274 (ITS), KP796345 (nuLSU), KP822145 (RPB1), KP822359 (MCM7), KP823521 (TSR1).

This comprises the specimens recovered within ‘P.isidiata D’ in ‘Protoparmelia tropical clade’ in Singh et al. (2015). Similar to Neoprotoparmeliaisidiata but differing in having a thicker thallus and shorter isidia.

AUSTRALIA. Same as type, J. A. Elix 39795 (CANB); Northern Territory, Melville Island, H. Streimann 42469 (B, CANB).