Chromosomal and morphological divergences in Atlantic populations of the frillfin goby Bathygobius soporator (Gobiidae, Perciformes)

Evidence of population fragmentation and speciation processes has been reported for several species of marine fish, including small cryptobenthics forms of Atlantic. Four populations of the frillfin goby Bathygobius soporator, which cover a wide geographical area of the Atlantic coast in North/Northeast Brazil, were cytogenetically analyzed and their morphological patterns compared. Continental populations of this species (denominated MA, RN, and BA) exhibited divergences in morphological and chromosomal characteristics compatible with interpopulation differentiation. However, specimens from Rocas Atoll (RA) displayed notable divergences in these parameters, corroborating molecular data that suggest they are a different species. Furthermore, the RN population showed intrinsic chromosomal markers, revealing a certain level of population structuring. Chromosomal and morphological patterns found confirm the biodiversity of B. soporator, substantiating an evolutionary scenario of population divergences and adaptation to new habitats.

► Populations of B. soporator were analyzed by cytogenetic and morphometrics procedures.
► Karyotype traits of Rocas Atoll individuals pointed to a different species.
► Accessory 5SrDNA sites are exclusive of the Natal population.
► All populations showed morphologically differentiated.
► The combined data indicate genetic structuring in Atlantic B. soporator populations.