While most Melastomataceae have poricidal anthers, Miconia sect. Hypoxanthus (former sect. Chaenanthera) has anthers dehiscing by longitudinal pores, resembling rimose openings. Anther development of three species (Mironia pusilliflora and M. laticrenata from this section and M. cinnamomifolia from sect. Glossocentrum) studied through SEM and light microscopy showed that all have an epidermis with a thick and striate cuticle, except for the dehiscence area. This area is covered by a non-striate epidermis which is associated with the septum that lies between the two thecae. During dehiscence the septum holds the non-striate epidermis, which is torn at the margins of the dehiscence area. Since anther opening of all three species follows the same pattern, in terms of tissues and mechanisms, we conclude that the circumscription of Miconia sect. Hypoxanthus should comprise all species with stamens that dehisce along the septum, resulting in narrow openings that extend from the anther apex to the base (as in M. pusilliflora) or from the apex until half of the anther length (as in M. laticrenata). Miconia section Chaenopleura also has anthers opening by longitudinal slits, hut these expose four locules, instead of the two in Hypoxanthus.