New Data on Warrana besnardi, a Tiny Bivalve Mollusk from the Southeastern Brazilian Coast

When size matters: the first comprehensive anatomical study of a species of “Condylocardiidae”, an extremely miniaturized bivalve

“…This condition is also found in the infaunal carditids and crassatellids, differing from the epifaunal byssally attached species of these families, in which there is an anterior inhalant current (Harry, 1966;Allen, 1968;Yonge, 1969;Taylor, Glover & Williams, 2005). Like all other archiheterodonts, W. besnardi has two pallial apertures, but the position of the mantle margin fusion in this species is more ventral in this species than in other archiheterodonts, which is reflected in the expansion of the antero-ventral shell margin during growth (Batistão & Passos, 2020). As illustrated in Fig.…”

“…140). Based on the prodissoconch size, Batistão & Passos (2020) suggested that W. besnardi has lecithotrophic development and suggested that it broods its young. In the present study, as no embryos or juveniles were found, brooding protection was not observed.…”

“…To address the limited anatomical knowledge of condylocardiids, focus herein is placed on a species that was recently explored for its unusual shell features, Warrana besnardi (Klappenbach, 1963) (Batistão & Passos, 2020). This species reaches up to 1.5 mm in shell length, and is the single member of the genus Warrana Laseron, 1953 in the Atlantic.…”

“…The genus encompasses 14 other species in the Pacific Ocean, all of them being extremely small-bodied (less than three mm in shell length; Middelfart, 2002b). Based on the larval shell of Warrana besnardi, Batistão & Passos (2020) hypothesized a lecithotrophic development, involving large eggs and brooding.…”