Antarctotetilla coactifera

Antarctotetilla coactifera (Lendenfeld, 1907)

Synonymy: Tethya coactifera Lendenfeld, 1907; Cinachyra coactifera (Lendenfeld, 1907); Craniella coactifera (Lendenfeld, 1907); Tetilla coactifera (Lendenfeld, 1907).

Material examined: Syntype of Tethya coactifera, ZMB Por 4175 Lendenfeld, 1907 from Kerguelen (Subantarctic). GenBank accession number: Syntype of Tethya coactifera, ZMB Por 4175 (MF168949, S1).

Description (Fig. 10). Globular, 5 cm in diameter, sponge (Fig. 10a). Surface smooth, slightly rugose. Oscules small and very scarce (Fig. 10b). Pores grouped in slight depressions (Fig. 10c), widespread on the sponge surface. Color yellowish brown in alcohol. Pseudocortex (Fig. 10d) made of auxiliary oxeas, loosely arranged, perpendicularly to the sponge surface. Not conspicuous basal spicule tufts in the syntype examined.

Spicules (Fig. 11; Table 1). Megascleres: oxeas I (Fig. 11a) large and fusiform: 2850–4310–5400 µm x 25–40 – 50 µm. Auxiliary small oxeas II (Fig. 11b): 470–686.6–960 µm x 10 –16.25–22.5 µm. Anatriaenes I (Fig. 11f): 7000–9400–11580 µm x 20 – 25.4–30 µm in size with long and thin clades: 150–167.7–200 µm; rhabdomes fusiform, thicker at the middle and filiform at the terminal part. Anatriaenes II: 2862.5–3647.8–4700 µm x 5–11 – 17.5 µm in size (Fig. 11e) with short clades: 20–47.5–70 µm and fusiform rhabdomes. Anatriaenes III (Fig. 11g): 3900–6620–9400 µm x 17.5–23.8–30 µm in size with thick clades: 75–110.6–140 µm; rhabdomes fusiform, thicker at middle and filiform at the terminal part. Protriaenes I (Fig. 11c): 3050– 4539.4–7200 µm x 12.5–14.7–20 µm, with clades: 50–121.3–200 µm long, usually one clade longer than the other two; rhabdomes tapering from the base of the clades to end in a filamentous termination. Protriaenes II (Fig. 11d): 1450–2245 –2960 µm x 7.5–9.2– 12.5 µm, clades: 10–61.7–112.5 µm, usually one clade longer than the other two; rhabdomes tapering to a filiform end. Trichodal protriaenes (Fig. 11h) very small with filamentous rhabdomes: 425–551–675 µm x 2.5–2.6–3.75 µm long and thin,10–18.3–50 µm long clades. Microscleres: Sigmaspires (Fig. 11i): 10–13.7–20 µm in length.

Skeletal arrangement. Bundles of oxeas, anatriaenes, and protriaenes spirally arranged from the central part to the sponge periphery.. Auxiliary oxeas arranged in palisade at the sponge periphery and scattered in the choanosome. Trichodal protriaenes concentrated at the peripheral zone. Sigmaspires throughout the sponge.

Distribution and habitat. Kerguelen (Lendenfeld, 1907 and Lévi, 1956).

Remarks. The type of Tethya coactifera Lendenfeld, 1907 also owns grouped pores, a pseudocortex made of auxiliary oxeas mainly concentrated at the peripheral zone. Thus, as suggested in Carella et al. (2016), T. coactifera belongs in Antarctotetilla. This species is very similar to A. grandis but does not possess the oscules on the apex of conical elevations, typical of the former species. Moreover, it has a different spicule size range than in the other known Antarctotetilla species: larger fusiform and auxiliary oxeas, and smaller clades of all anatriaenes and protriaenes, and also has a third type of anatriaene (anatriaenes III). The anchoring basal mass composed of anatriaenes, reported by Lendenfeld (1907) was not visible in the syntype.