New species of the genus Elachisina (Gastropoda: Elachisinidae) from northeastern Brazil.

The family Elachisinidae Ponder, 1985 includes minute marine gastropods that live predominantly in the sublittoral zone (Ponder & Keyzer 1998; Rolán & Rubio 2001; Rolán & Gofas 2003). Most elachisinids have been included in the genus Elachisina Dall, 1918 based on their shell morphology (Warén 1996; Rolán & Rubio 2001; Rolán & Gofas 2003), consequently, very little is known about the habitat and ecological niche of the species (Ponder & Keyzer 1998; Rolán & Gofas 2003). Elachisina floridana (Rehder, 1943) is the only Atlantic congener collected alive, and is known to live beneath rocks and in rocky crevices in the intertidal zone to about 1 m depth in the Bahamas and Caribbean Sea (Ponder 1985; Ponder & Keyzer 1998; Rolán & Gofas 2003; Redfern 2013). Eastern Atlantic E. canarica (Nordsieck & García-Talavera, 1979) was also collected alive from the Canary Islands, but with no information on the habitat (Rolán & Gofas 2003). The islands of the northeastern Atlantic and West Africa are the regions with the greatest Elachisina richness known, totaling nine species (Rolán & Rubio 2001; Rolán & Gofas 2003). Only E. floridana has been recognized so far to be widely distributed throughout the Western Atlantic (Rolán & Gofas 2003; Rios 2009; Redfern 2013).

New species of Caecum (Caenogastropoda: Rissooidea: Caecidae) from the Atlantic coast of South America (Brazil) with a description of the protoconch and growth stages.

Two new species of Caecinae are described from the Brazilian coast. Specimens of Caecum metamorphosicum sp. nov. were collected from northern to southeastern Brazil. The teleoconch V of this species is characterized by strong, raised, quadrangular, rather closely arranged axial ribs, except the last two to three preceding the aperture, which are slightly larger and more widely separated, and a finger-shaped mucro. Specimens of Caecum trindadense sp. nov. were only collected from southeastern Brazil. The teleoconch VI of this species is characterized by conspicuous, sinuous longitudinal striae, finger-shaped mucro, and rather smooth varix. The protoconch and all growth stages of C. metamorphosicum sp. nov. and C. trindadense sp. nov. are described and figured here based on scanning electron microscopy. A brief discussion on the biodiversity of Caecidae on the Atlantic coast of South America is given. This report provides a basis for the better recognition of growth stages among members of Caecinae.