Psychotria oxyalabastron T.Srisuk & Chamch., sp. nov.

Psychotria oxyalabastron is similar to P. cambodiana Pierre ex Pit. in having tomentose, puberulous or pilose indumentum on branches and the lower leaf surface (at least on the venation), bifid or bilobed stipules, elliptic or oblanceolate laminas, loose corymbose-like thyrsiform inflorescences, and glabrous floral buds. However, it differs from P. cambodiana in the glabrous upper leaf surface (vs pilose), glabrous on intercostal areas on the lower leaf surface (vs pilose), acute floral bud apex with corolla protrusion (vs rounded floral bud apex without corolla protrusion), shorter corolla tube 1.3–1.4 mm long (vs 2–2.3 mm long), and the glabrous to sparsely puberulent ovary (vs tomentose or pilose).

Etymology.— The specific epithet ‘oxyalabastron’ refers to the acute shape of the floral bud, and is modified from the Greek “oxy-” for acute, combined with “alabastrum” for floral bud (alabastron = adjective form).