thalline exciple (noun, pl. thalline exciples;ascocarp term; synonymous original Latinized form: sl. excipulum thallinum, pl. excipulae thallinae; alternatively: sl. amphithecium, pl. amphitheciae) – an anatomical term referring to an additional lateral layer surrounding an ascocarp, formed from thallus hyphae and photobiont cells; in apothecioid ascocarps forming a thalline margin, and in perithecioid ascocarps forming an involucrellum; generally with a similar structure as the surrounding thallus; ontogenetically derived not from the ascocarp itself but from the thallus; frequently but not always present in lichenized ascomycetes, absent from non-lichenized ascomycetes; if well-developed sometimes replacing (or at least diminishing) the proper exciple. Terms describing parts of the thalline exciple (amphithecium): cortical exciple, medullary exciple, amphithecial cortex. Related terms: proper exciple, lecanorine, involucrellum. This is:part of ascocarp.