A survey of corticolous crustose lichen collections in connection with the Flora Neotropica project revealed a number of undescribed species of Trichothelium. While a few typically foliicolous taxa may occasionally be found on bark, five species seem to be exclusively corticolous, all with a Trentepohlia photobiont. Three of them are new species: T. angustisporum, T. caudatum, and T. kalbii spp. nov. A key is provided to all five corticolous species, accompanied by data on their distribution and ecology. A considerable range extension is reported for T. horridulum, with new collections from Costa Rica and north-eastern Brazil.