Acanthotetilla walteri Peixinho, Fernandez, Oliveira, Caíres & Hajdu, 2007 (Tab. 1–2, 10; Fig. 13A–G) Studied material. MNRJ 21180 — P.M.M. Coroa Alta (16°14.056′ S, 38°57.252′ W, Santa Cruz Cabrália, BA, Brazil), intertidal, coll. Leite, D., 25 th March 2019. Additional material. MNRJ 23318 — Recife do Mutá (16°34.49117′ S, 39°00.40300′ W), Santa Cruz Cabrália, BA, Brazil), intertidal, coll. Fernandez, J.C. & Clerier, P., 12/xii/2020. Description. Encrusting (1 cm x 2 cm x 0.1 cm) to endolithic. Surface irregular, abundantly pierced by spicules. Consistency firm, but compressible. Color in vivo not recorded, and light beige in fixative (Tab. 10). Skeleton. Ectosomal skeleton unspecialized, merely a radial arrangement of abundantly triaenes (protriaenes and prodiaenes) and oxeas piercing the surface (Figs. 13A–B). Sigmaspires concentrated slightly underneath the surface (Fig. 13C); some acanthoxeas scattered too. Choanosomal architecture radially organized by oxeas and rhabdome of protriaenes, with abundantly and scattered acanthoxeas and sigmaspires (Figs. 13A, E). Spicules. Megascleres (Tab. 10; Figs. 13A–G): protriaenes or prodiaenes (Figs. 13A–B), rhabdomes slightly stouter right beneath the cladome, gradually thinning to the apex (mostly broken),> 290–524.4–972 x 1–2.1–4 µm (n=7), cladi 30–44.7–59 x 1–2.0–3.8 µm (n=10); acanthoxeas (Figs. 13C, F–G), slightly curved centrally, sharp points, heavily spined, 233–272.6–371 x 9–15.4–21 µm; and oxeas (Fig. 13F), slightly curved, sharply pointed, 704–972.5– 1180 x 6 –9.3– 12 µm (n=9). Microscleres (Tab. 10; Figs. 13C): sigmaspires (13C), 9–12.0–14 µm. Distribution. Only known from northeast Brazil: Camaçari (type locality), the northern sector of BA, and Santa Cruz Cabrália, the southern sector of BA—new record. Ecology. The specimen was growing in a piece of hard coral (viz., not in live), which is associated with calcareous algae and hydrozoans. Remarks. Our material matches the original description of A. walteri by Peixinho et al. (2007), as amended in Fernandez et al. (2012). The species was originally described from northern Bahia (22 to 35 m depth) and had not yet been reported again. Here we are recording it from an intertidal area in southern Bahia. The endolithic/cryptic habit of A. walteri likely explains the few records of the species this far, which is absent from large taxonomic inventories such as those by Muricy et al. (2006, 2011), Moraes (2011) and Moura et al. (2016). Spicules A bud made of spicules and spongin was observed (Fig. 13D). So far, a similar reproductive specialisation has not been reported from other known species of Acanthotetilla (cf. van Soest 1977, Peixinho et al. 2007, Fernandez et al. 2012). However, surface buds were reported from other tetillid sponges, for instance: Cinachyrella apion (Uliczka, 1929) from the western Atlantic (Ŗtzler & Smith 1992), C. australiensis (Carter, 1886) from the Indopacific (cf. Ŗtzler & Smith 1992) and C. anatriaenilla Fernandez, Kelly & Bell, 2017 from the west Pacific (Fernandez et al. 2017). The latter two species share spined microxeas, which resemble acanthoxeas of Acanthotetilla species. Although acanthoxeas and microxeas are acanthose monaxonic spicules (Fernandez et al. 2012), the origin of both (as homologous or not) has still not been determined by phylogenetic analysis (Szitenberg et al. 2013). Some important observations about spicules of A. walteri should be made here, a consequence of imprecisions in the original description of the species. In regard to protriaenes, a single category is present, with rhabdome thickness of 3.6–3.8–7.2 µm, as already pointed out in Fernandez et al. (2012). As for the acanthoxeas, also only a single category is present, the smaller ones shown in Peixinho et al. (2007) being misinterpreted due to the angle of the spicules in the SEM image. Micrometric values for these spicules are 238–297.1–378/28–28.0–28 µm as mentioned in Fernandez et al. (2012), and reproduced in Table 10.

Published as part of Bettcher, Larissa, Fernandez, Julio C. C., Gastaldi, Marianela, Bispo, André, Leal, Camille V., Leite, Dora, Avelino-Alves, Dhara, Clerier, Pedro H. B., Rezende, Dafinny, Gulart, Clara M. R., Pinheiro, Ulisses & Hajdu, Eduardo, 2023, Checklist, diversity descriptors and selected descriptions of a highly diverse intertidal sponge (Porifera) assemblage at Costa do Descobrimento (Bahia, Brazil), pp. 443-489 in Zootaxa 5277 (3) on pages 470-475, DOI: 10.11646/zootaxa.5277.3.2, http://zenodo.org/record/10268325