Placospongia cristata Boury-Esnault, 1973

(Tables 1–2, 7; Figures 10A–J)

Synonymy. Placospongia melobesioides, sensu Schmidt (1870) [non P. melobesioides Gray, 1867b]. Detailed synonymy in van Soest (2009).

Studied material. MNRJ 20489, Mucugê (16°29.861′ S, 39°4.068′ W, Arraial D’Ajuda, Porto Seguro, BA, Brazil), intertidal, coll. Leite D., 20 th March 2019 ; MNRJ 20508, Coroa Vermelha Reef (16°19.384′ S, 38°59.927′ W, Santa Cruz Cabrália, BA, Brazil), intertidal, coll. Hajdu, E. & Fioravanso, A. 21 st March 2019 .

Description. Thickly encrusting (less than 1 mm thick), 2.8 cm maximum length, with slender plates (<1 mm thick) and grooves (ca. 1 mm wide) on the surface. Consistency hard, but plates feel like crunchy flakes. Color in vivo orangey-brown overall, dull on plates and brighter in the grooves. Dark beige in fixative (Fig. 10A).

Skeleton. Ectosome with cortical plates of selenasters and smaller tylostyles. The choanosome with abundant dispersed spicules of every kind, aside the larger tylostyles, organised in ascending columns up to 200 µm thick beneath the cortical plates (Figs. 10B–D).

Spicules. Megascleres (Tab. 7; Figs. 10E–F): tylostyles, 251–480.1–797 x 6–10.1–15 µm. Microscleres (Tab. 7): selenasters, 54‒61.8‒71 x 39‒49.0‒55 µm (larger diameter x smaller diameter; Fig. 10G); spherasters, 15‒17.9‒ 25 µm (Fig. 10H); and microrhabds (varying among microspherasters, microamphiasters, microspirasters; Fig. 10I), ca. 1.4‒2.3 µm (n= 2).

Distribution. Previously Pernambuco (Brazil — Boury-Esnault 1973), Caribbean (Curaçao — Arndt 1927; Barbados — Hechtel 1969). New record—Costa do Descobrimento, BA, Brazil. The species had been previously recorded for BA (Todos os Santos Bay, Salvador), but without any accompanying description (Bispo et al. 2006).

Ecology. Spreading over calcareous substrate in a sciophilous microhabitat, next to a diverse assemblage of organisms comprising other sponges, and abundant filamentous organisms. This species appears rarer than P. ruetzleri in the study area (our observations) as well as from other areas of BA (Mácola & Menegola 2021).

Remarks. Currently, the distinction between the Western Atlantic P. cristata and the Indo-Western Pacific P. melobesioides rests on the tylostyles of the latter reaching larger dimensions. Van Soest (2009) suggests that microspherasters (= microrhabds in the present study) could be present in the type material of P. cristata, which is confirmed by Dr. J. Sandes (pers. com.; Museu Nacional, Rio de Janeiro, Brazil), who has analysed the species’ type material. Moreover, we found a few spirasters in specimen MNRJ 20489; ca. 20 µm long, which seem to be absent from the type specimen (Dr. J. Sandes, pers. com.; Museu Nacional).