A new species of Latrunculia (Biannulata) (Porifera: Demospongiae) from Rio de Janeiro, south-eastern Brazil

In this study, we describe a new species of Latrunculia (Demospongiae: Poecilosclerida) from shallow waters in Rio de Janeiro, south-eastern Brazil. Latrunculia (Biannulata) janeirensis sp. nov. is cushion-shaped, brown in color, with raised oscular papillae and spherical or fungiform areolate porefields, a confused choanosomal skeleton without spicule tracts, and small styles. The developmental stages of the anisodiscorhabds have a thin axis and four whorls with irregular, non-ramified rays. The manubrium and the median whorl are only slightly larger than the apical and subsidiary whorls, making the spicule appear almost symmetrical. Fully developed anisodiscorhabds have a stout axis; the apical whorl is ramified, spined, with leaf-like rays. The manubrium is larger and smoother than the apical whorl, and the median and subsidiary whorls have pointed, spined rays fused only at their bases. This is the first species of Latrunculia described from Rio de Janeiro State and the second from Brazil. This new record extends the distribution of the subgenus Biannulata to the south-western Atlantic.