A new species of stygobitic aeglid from lentic subterranean waters in southeastern Brazil, with an unusual morphological trait: short pleopods in adult males

摘要

Abstract Aegla charon n. sp. is endemic to the ?￠????Lago Subterr???￠neo?￠???? cave from the Alto Ribeira karst region, southeastern Brazil. The most remarkable morphological trait observed in the new species was the presence of partially developed pair of uniramous pleopods 2?￠????5 in adult male specimens, whereas the absence of these pleonal appendages is the general condition in this sex in Aegla Leach, 1820. Some of the pleopods are even morphologically similar to those typically observed in adult females in that they may also be two-segmented, only shorter in size. The pigmented area of the cornea is slightly reduced, which is probably a troglomorphic adaptation to subterranean habitats. Aegla charon n. sp. is also the only obligate cave-dwelling aeglid known to inhabit lentic subterranean waters. A key to all species from the Alto Ribeira karst area is provided.