Paratetilla arcifera Wilson, 1925

Santodomingo, Nadiezhda & Becking, Leontine E., 2018, Unravelling the moons: review of the genera Paratetilla and Cinachyrella in the Indo-Pacific (Demospongiae, Tetractinellida, Tetillidae), ZooKeys 791, pp. 1-46 : 8-10

Paratetilla arcifera Wilson, 1925 Figs 3, 4, 5

Paratetilla arcifera Wilson, 1925: 380; plate 40, fig. 2; plate 48, fig. 6 (type seen).

Material examined.

Holotype USNM 21278, Albatross Stn. 5400, Malapascua Island, Cebu, Philippines, 46 m, 16 Mar 1909. INDONESIA. East Kalimantan, Berau reef, RMNH.POR.11131, RMNH.POR.11265, RMNH.POR.11266, RMNH.POR.11269, RMNH.POR.11267, RMNH.POR.11268, RMNH.POR.11270, RMNH.POR.11271, RMNH.POR.11272, RMNH.POR.11273. Bali, RMNH.POR.1870. Java, Thousand Islands, RMNH.POR. 2076. Sulawesi, Bunaken, RMNH. POR.3114; Manado RMNH.POR.3114. Ternate , Ternate reef, RMNH.POR.11310. West Papua, Kerupiar Island reef, RMNH.POR.11280; Outside Ctenophore Lake, RMNH.POR.11275; Gam Island, RMNH.POR.11277, RMNH.POR.11278, RMNH.POR.11279, RMNH.POR.11274, RMNH.POR.11276. TAIWAN. Reef, RMNH.POR.3196, RMNH.POR.3206, RMNH.POR.3225, RMNH.POR.3236.

Description.

External morphology. Globular sponges, size from 3 to 6 cm in diameter (Figs 3A, 4A). Surface hispid due to the projecting spicules, covered by numerous porocalices. Porocalices are bowl-shape, with oval apertures, up to 10 × 5 mm and 6 mm deep, few, mainly on the top surface of the sponge; in preserved material, most porocalices remained open (Figs 3A, 4A). Color generally bright orange when alive, which turns darker or even brown in ethanol. No granules in choanosome. Fleshy consistency.

Skeleton. No cortex. Skeleton composed by bundles of oxeas and triaenes radiating from a central core, and spaced between each other, giving a softer consistency (Figs 3C, D, 4C).

Megascleres. Holotype and Indonesian specimen size ranges are summarized in Table 4. Holotype: Oxeas 1650 –2435– 4500 mm × 20 –36.8– 65 mm; anatriaenes very abundant (Figure 3J), rhabds generally broken, up to 6000 × 10 mm, apparently tapering to dimensions of <1 mm, cladi thin, slightly flattened, 40 –68– 80 mm × 25 –39.4– 45 mm × 5 –8.2– 10 mm; few protriaenes (Figure 3K,L), thinner and small cladi (40 –65– 80 mm × 60 –85– 110 mm), rhabds mostly broken, up to 5000 × 15 mm, tapering to dimensions of <1 mm; two types of calthrop-like short shafted triaenes, one type with four rays of which three are short (150-300 mm) and one is large (400 mm) (Figure 3H), the other type has three rays of almost equal length up to 400 mm (Figure 3 F-G, I); calthrops are abundant in some specimens, but can be in very low numbers till almost absent in some others, they are located immediately below the surface, constituting a thin layer that can be missed in some spicule preparations.

Microscleres. Thin microxeas are common, 180 –308.4– 380 mm, ‘hair-like’ (Figs 3M, N, 4R, S). Sigmaspires, 7.5 –12.5– 17.5 mm, C-S shape (Figs 3O, 4T).

Ecology.

Coral reef habitats at depths from 1- 20/30 m. Absent from marine lakes, mangroves and other localities with higher sedimentation and/or variable salinity.

Distribution.

Occur in coral reefs of Berau, Bunaken, Ternate , and Raja Ampat. An additional record from its type locality, Philippines (Wilson, 1925) could be inferred from the literature (see Longakit et al. 2005: Figure 9 as P. bacca ), and collections from Taiwan (Figure 5).

Remarks.

Spicule sizes for most Indonesian specimens vary within the holotype ranges, except for the Ternate population, which exhibits smaller sizes and lack of protriaenes (Table 4). The typical orange color and ‘fleshy’ soft consistency are easy distinctive characters of this species (Figure 4A). The differences between P. arcifera and its congener P. bacca lie in the stark orange coloring, the fleshy consistency, the lack of granules, the larger porocalices, and thin microxeas generally longer than in P. bacca . P. arcifera specimens are typically larger than P. bacca. We, furthermore, deem P. arcifera a distinct species from P. bacca , based on recent molecular phylogenetic analyses that included P. arcifera (genbank accession number LT628349) and P. bacca (LT628350) specimens reviewed in our current study and support the hypothesis of two species ( Schuster et al. 2017).