FIGURES 4A–D. Pisidium lebruni, anatomy. A. Gross anatomy. B in Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America

FIGURES 4A–D. Pisidium lebruni, anatomy. A. Gross anatomy. B. Left nephridium in dorsal view. C. Nephridia in lateral view, open type at left, closed type at right. D. Inner view of inner demibranch showing the position of brood sac in early stage of development. (aa. anterior adductor muscle; al: ascending lamellae; as: anal siphon; bs: brood; dl: descending lamellae; dln: dorsal lobe of nephridium; f. foot; h: heart; irm: inner radial mantle muscles; ld: left demibranch; ll: lateral loop of nephridium; n: nephridium; pa: posterior adductor muscle; pd: pericardial duct; pr: pedal retractor muscle; rd: right demibranch).