Sclerocarps: undescribed propagules in a sand-inhabiting marine fungus

Abstract

Varicosporina ramulosa Meyers et Kohlm., a Fungus Imperfectus living on detritus of the intertidal zone in the tropics and subtropics, forms sclerotia-like propagules attached to grains of sand. These hitherto undescribed reproductive structures are shown to survive extreme conditions in beaches and to be homologues of Ascomycete fruiting bodies (ascocarps). Based on laboratory experiments and microscopical observations, we postulate here that V. ramulosa is an Ascomycete (probably in Halosphaeriaceae) that in the course of evolution has lost its ability to reproduce sexually. Accordingly, we propose the new term sclerocarp (from the Greek skleros = hard, karpos = fruit) to describe modified ascocarps that have permanently lost their sexual capacity and function now as sclerotia, i.e., resting structures. Cell walls in the center of sclerocarps contain pit connections that have been reported only from ascocarps of Halosphaeriaceae.