Acarnus toxeata Boury-Esnault 1973

Acarnus toxeata Boury-Esnault, 1973 (Fig. 5A–K; Table 3) Synonymy: Acarnus toxeata Boury-Esnault, 1973: 285, van Soest et al., 1991: 62, Nascimento & Pinheiro, 2023: 529. Type locality. Brazil, Bahia State (18º09’S 38º39’W). Material examined. MNRJ 4903 and 4913, Brazil, Espírito Santo State, #y17, 18º39’48”S 37º52’13”W, 65 m depth, coll. R. V., “Astro Garoupa”, through dredging, 29. VI.2001; MUCIN 0152, Brazil, Bahia State, Camamu Bay, intertidal, 13°54’14”S 39°00’34”W, coll. Guerrazzi, M. C., free diving, 25.III.2005; UFBA 2700, Brazil, Bahia State, Camamu Bay, Cairu, 13°32’31.56”S 38°35’27.96”W, 9 m depth, Coll. Lopes, U., free diving, 28. VIII.2004; UFBA 2703, Brazil, Bahia State, Camamu Bay, Marau, 13°54’33.4”S 38°59’40.4”W, Coll. Guerrazzi, M. C., free diving, 06. VIII.2005; UFBA 2704, Brazil, Bahia State, Camamu Bay, Marau, 13°53’42.6”S 39°00’28.1”W, 3 m depth, Coll. Guerrazzi, M. C., free diving, -. IX.2003; UFBA 2705, Brazil, Bahia State, Camamu Bay, Maraú, 13°53’42.6”S 39°00’28.1”W, 9.15 m depth, Coll. Guerrazzi, M. C., free diving, 30.X.2004; UFBA 3170, Brazil, Bahia State, Camamu Bay, Cairu, 13°32’29.5”S 38°59’29.7”W, 11.7 m depth, Coll. Guerrazzi, M. C., free diving, 25.IX.2004. Diagnosis. Thinly (0.5–2 mm) incrusting in size; color of living specimens described as brown; accolada toxa (I) extremely long: 500–945 µm (from Boury-Esnault, 1973). Description. Finely embedded in coral fragments and coralline algae. With an average thickness of 1 mm and indefinite length (MNRJ 4913). Surface generally smooth; however, in some regions it is rough due spicules projections. Fragile consistency, tearing easily. Color in life varying from orange (MNRJ 4913) to red (MNRJ 4903) and, when fixed, it appears as a thin semi-transparent film. Oscules not observed. Skeleton. Detachable ectosome, basically formed by perpendicular tylotes. Organic choanosome with diffusely distributed sand grains. In this region, there are also bundles of megascleres echinated by cladotylotes and with scattered microscleres. Spicules (Figure 5A–K). Megascleres: styles stout (Fig. 5F–G), slightly curved, with microspined ends (430– 536.9–646/ 7.9–9.6–13.3 µm). Tylotes (Fig. 5H–I) slender, straight and smooth, with microspined ends (295–349.7– 436/ 5.6–6.9–7.9 µm). Cladotylotes I (Fig. 5A–B) microspined with four clads (210–263.6–311/ 5.3–8.1–10.6 µm). Cladotylotes II (Fig. 5C–D) with a highly spinated shaft (71.8–115.2–159.6/ 2.2–3.2–5.3 µm). Microscleres: Toxas I (accolada) (Fig. 5K) thin and straight, with a short and shallow curvature at the center (106–459.2–825 µm); Toxas II, deeply curved (61.9–155.8–272.8 µm); Toxa III (oxhorn) (Fig. 5J) (31.9–57.7–82.4 µm). Palmate isochelae (Fig. 5E) (7.9–10.6–13.3 µm). Distribution. Endemic from Brazil: Bahia (Boury-Esnault, 1973; van Soest et al. 1991; Muricy et al. 2011; Nascimento & Pinheiro 2023) and Espírito Santo States (Muricy et al. 2006; Muricy et al. 2011). Remarks. Boury-Esnault (1973) did not designate the type material for this species, but van Soest et al. (1991) has designated the holotype from the original series of syntypes. The examined material conforms to A. toxeata based on the redescription of the type material (2 microscopic slides) by van Soest et al. (1991). Additionally, the spicule measurements of the material examined match the specimens of A. toxeata recently redescribed by Nascimento & Pinheiro (2023) from the northeast Brazil region. A variation of four to six clads in cladotylotes I and II have been reported by van Soest et al. (1991) and Boury-Esnault (1973) for the species. Part of our material (UFBA 2700, 2703, 2704, 2705) has cladotylotes with four clads. We consider it to be only an intraspecific variation. Toxas I were only present in two specimens among examined material (MNRJ 4913 and MUCIN 0152) and varied greatly in length (106–825 µm). The type material of A. toxeata described by Boury-Esnault (1973) and redescribed by van Soest et al. (1991) presents strictest length variation 500–945 µm. Lower variations (<500 µm) had never been registered for A. toxeata until then, and it may be an intraspecific variation. Acarnus toxeata has been originally reported from at 7 m to 50 m depth by Boury-Esnault (1973) and van Soest et al. 1991. Recently, Bettcher et al. (2023) have found the species in intertidal areas from reefs of the south Bahia region. Here, we expanded the bathymetric range down to 65 m depth and recorded for the first time for the state of Espírito Santo.