ABSTRACT Studies that address biodiversity and its supporting mechanisms in different ecosystems are fundamental to understanding the relationships between species and the prevailing environmental conditions within each habitat type. This study presents information on the phenology of Promestosoma boggianii (Silvestri, 1898) and its association with seasonal flood and dry events in a floodplain of Mato Grosso’s northern Pantanal region, Brazil. Sampling was carried out in three areas located between the Bento Gomes and Cuiabá rivers, on the Porto Cercado Road, Poconé-MT. Each sample area was composed of two treatments: (I) floodable habitats and (NI) non-floodable habitats. Three quadrats (10 x 10 m) were established within each treatment, with sampling carried out using pitfall traps and mini-Winkler extractors during the dry season, rising water, high water and receding water phases for the duration of two hydrological cycles within the Pantanal (2010/2011 and 2011/2012). A total of 295 P. boggianii individuals were sampled at different stages of development (except stages I and II), distributed between the rising water (209 ind., 70.8%), dry (76 ind., 25.8%) and receding water (10 ind., 3.4%) seasons. No specimens were sampled during the high water season. The higher abundances recorded between the dry and rising water seasons, primarily at early stages of development, indicate that P. boggianii is characterized as a univoltine species in these habitats. The data demonstrate that individuals of P. boggianii were more abundant in floodable habitats. In addition, the results show that the life cycle of this diplopod is sinchronized to the seasonal nature of this floodable environment, as a strategy to survive the extreme conditions of terrestrial and aquatic phases Brazil’s northern Pantanal region.