Paratetilla bacca (Selenka, 1867)

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 : 5-7

Paratetilla bacca (Selenka, 1867) Figs 1, 2

Stelletta bacca Selenka, 1867: 569, pl. xxxv, figs 14, 15 (type not found, material from type locality seen).

Tethya merguiensis Carter, 1883: 366, pl. xv, figs 6-8; Carter, 1887: 80 (type seen).

Tetilla merguiensis ; Sollas, 1888: 14; Topsent, 1897: 441, pl. xviii, fig. 4-5, pl. xxi figs 34.

Tetilla ternatensis Kieschnick, 1896: 527. Thiele, 1900: 39, pl. ii, fig 13; Not Tetilla ternatensis Lindgren, 1898: 329 pl. 17, fig. 14; pl. 19, Fig. 25 a-e, a’, b’.

Tetilla bacca ; Lindgren, 1897: 485; Lindgren, 1898: 328; Thiele, 1900: 39, pl. ii, fig 13; Kirkpatrick, 1900: 132 (material seen); Lendenfeld, 1903: 19.

Tetilla amboinensis Kieschnick, 1898: 10.

Tetilla violacea Kieschnick, 1898: 15.

Tetilla rubra Kieschnick, 1898: 18.

Paratetilla cineriformis Dendy, 1905: 97, pl. iii, fig. 7 (type seen).

Paratetilla eccentrica Row, 1911: 306, pl. xxxv, fig. 1, pI. xxxvi, fig. 8 (type seen).

Cinachyra amboinensis ; Hentschel, 1912: 331.

Paratetilla bacca ; Dendy, 1922: 21 (material seen).

Paratetilla bacca var. violacea ; Dendy, 1922: 22, pl. 1, fig. 6 (material seen).

Paratetilla lipotriaena de Laubenfels, 1954: 244, text figure no. 168 (type seen).

Material examined.

Neotype ZMA.POR.13029, Tutuila Island, American Samoa. Holotype of first junior synonym Tethya merguiensis Carter, 1883 (?) NHMUK 1894.11.16.17, Mergui Archipelago, Myanmar. Holotype NHMUK 1954.2.23.106 Gulf of Manaar, Sri Lanka (as Paratetilla cineriformis Dendy, 1905). NHMUK unreg. type, Crossland Collection, Red Sea (as Paratetilla eccentrica Row, 1911). NHMUK 1898.12.20.19, Flying Cove Fish, Christmas Islands (as Tetilla bacca = Paratetilla merguiensis Kirkpatrick, 1900). NHMUK 1921.11.7.10, Sealark Sponges, Indian Ocean (as Paratetilla bacca var. violacea ). Holotype USNM 23049, East part of Lagoon, Ponape, Caroline Islands, 1 Aug 1949 (as Paratetilla lipotriaena de Laubenfels, 1954). INDONESIA. Bali, Bali reef, RMNH.POR.1732; East Kalimantan, Berau reef, RMNH.POR.11281, RMNH.POR.11282, RMNH.POR.11283; Kakaban Lake, RMNH.POR.11289, RMNH.POR.11290, RMNH.POR.11291, RMNH.POR.11292, Haji Buang Lake, RMNH.POR.11284, RMNH.POR.11287, RMNH.POR.11288, RMNH.POR.11285, RMNH.POR.11286, RMNH.POR.3515. Sulawesi, Bunaken reef, RMNH.POR.3100, RMNH.POR.3106, RMNH.POR.3115; Bunaken mangrove, RMNH.POR.2819; Spermonde Archipelago, ZMA.POR.13221. Ternate , Ternate reef, RMNH.POR.5344, RMNH.POR.5467. West Papua, Wallace Lake, RMNH.POR.11293, RMNH.POR.11294, RMNH.POR.11295; Outside Wallace Lake, RMNH.POR.11296, RMNH.POR.11297, RMNH.POR.11298; Ctenophore Lake, RMNH.POR.11302; Gam Mangrove, RMNH.POR.11299, RMNH.POR.11300, RMNH.POR.11301; Outside Ctenophore Lake, RMNH.POR.11303; Big Caulerpa Lake, RMNH.POR.11304; Gam Island, RMNH.POR.11305, RMNH.POR.11306, RMNH.POR.11307.

Other material: East Kalimantan, Makassar Straits, ZMA.POR.1735, Siboga Expedition, St. 81. Singapore, RMNH.POR.2506, RMNH.POR.2512. Western Indian Ocean, ZMA.POR.20673.

Description.

External morphology. Globular sponges, size between 1 and 5 cm in diameter. Surface hispid due to the projecting spicules, covered by numerous porocalices (Figure 1A, B). Porocalices are bowl-shape, with oval to circular apertures, up to 5 mm in diameter and 7 mm deep, numerous, scattered uniformly over the surface of the sponge; in preserved material, some porocalices are closed and only a narrow aperture is visible giving to the sponge a rough appearance. External color generally brown when alive, which turns dark brown in ethanol, choanosome light brown, and has a 'dried out’ appearance (Figure 1B). Numerous small dark brown granules in the tissue (Figure 1E, F). Consistency compact.

Skeleton. No cortex. Choanosomal skeleton composed by bundles of oxeas and triaenes radiating from a central core, ⅕-⅓ of the diameter of the sponge.

Megascleres. The material from Indonesia and the type of P. merguiensis have oxeas 850 –3085.3– 4500 mm × 5 –41.5– 65 mm (Table 4, Figure 1E, D, G). Anatriaenes always present, very abundant, cladi stout, slightly flattened, 20 –62.6– 100 mm × 12.5 –48.3– 75 mm, long rhabd up to 6000 × 20 mm, tapering to dimensions much less than 1mm (Figure 1H, I). Protriaenes scarce in some specimens and absent in the type specimen; when present, they exhibit two different shapes, the first one with stouter and smaller cladi, the second one with thinner and larger cladi (27.5 –53.9– 100 mm × 37.5 –107.4– 200 mm × 2.5 –6.5– 12.5 mm), rhabd up to 5850 × 15 mm, tapering to dimensions of <1 mm. Calthrop-like short shafted triaenes, three types are distinguished with a wide range of sizes, from which measurements are shown as a general summary (Table 4). In the first type, four rays can be recognized (Figure 1L), three of them large, up to 400-600 mm, and a short one up to 100 mm long, usually pointing down to the centre of the body; the second one with three rays, almost the same length up to 400 mm; and the third one with three rays as well, two of them in an angle of 180° and the other one perpendicular, 50-100 mm. The calthrops are located immediately below the surface, constituting more or less a homogeneous layer.

Microscleres. Thin microxeas are common, 105 –241.6– 380 mm, ‘hair-like’. Sigmaspires, 10 –14.1– 25 mm, C-S shape (Figure 1F, M).

Ecology.

Inhabiting all studied environments in Indonesia, including coral reefs, mangroves, and marine lakes. Specimens more common in mangroves and marine lakes, and shallow reef flats where they are usually found on dead coral skeletons or coral rubble, typically ranging in depth from 0-5m. No specimens collected from deeper coral reefs in Indonesia.

Distribution.

Paratetilla bacca has a wide distribution in Indonesia, including Berau, Bunaken, Raja Ampat, Ternate , and Java. Previous Indonesian records are from Spermonde Archipelago ( Becking et al. 2006), Berau ( de Voogd et al. 2009), and Raja Ampat ( Becking 2008). In addition, this species has also been reported from Seychelles Islands ( Thomas 1973), Southwest Madagascar ( Vacelet et al. 1976), Zanzibar ( Pulitzer-Finali 1993), Thailand ( Putchakarn 2007), Singapore ( Lim et al. 2008), Philippines ( Longakit et al. 2005) (Figure 2).

Remarks.

We did not succeed in locating the holotype of Paratetilla bacca , despite concerted effort. At this time, we assume that the type is no longer available. The description by Selenka of the type specimen does not mention the occurrence of any type of sigmaspires. It is a matter of speculation whether Lindgren (1897) actually examined Selenka’s material to propose Carter’s species Paratetilla merguensis as a junior synonym to Paratetilla bacca , or whether he based his conclusion merely on the literature. It is possible that sigmaspires may have been overlooked by Selenka in his original description and drawings, yet the arrangement of the megascleres in the skeleton shows a clear similarity with Carter’s species P. merguensis (Suppl. material 2, Figure S1). In contrast to Selenka’s description, Carter (1883) included a complete and detailed account of P. merguiensis , which was verified through examination of two slides deposited in the NHM collection (NHMUK 1894.11.16-17); few oxeas are complete in these slides (most broken), therefore limited variation of this character was observed. For most of spicule types enough measurements were possible. Although we did not succeed finding Selenka’s type, we did examine one specimen and its associated slide preparation from Samoa identified as P. bacca (ZMA.POR.13029), which has all the characteristic spicules, including sigmaspires, that are present in our specimens from Indonesia (Figure 1C-F). This material is designated here with the status of neotype following the rules of the International Code of Zoological Nomenclature, article 75. Therefore, we conclude that P. bacca is a valid species, and subsequent species should be designed as junior synonyms. In all of our Paratetilla samples, we have furthermore not encountered one specimen without sigmaspires. Here, we show the measurements of the holotype of P. merguiensis , as well as specimens from different localities in Indonesia (Table 4). Although there is a large variation in spicules sizes among the different localities, there was also great intra-specific variation and we did not find any reason to declare the validity of any junior synonym included in this revision. In general, populations from marine lakes (Kakaban and Haji Buang) exhibit smaller spicules in comparison with their reefal counterparts at the same localities (Table 4). This variation could be a response to different environmental conditions within the marine lakes ( Becking et al. 2011), or a consequence of genetic selection after isolation of these populations about 8000-10000 years ago ( Dawson and Hamner 2005, Becking et al. 2013, Becking et al. 2016), or a synergistic effect between environmental and genetic factors.

According to the WPD ( van Soest et al. 2018), other four valid Paratetilla species are P. amboinensis (Kieschnick, 1898), P. lipotriaena de Laubenfels, 1954, P. corrugata Dendy, 1922 and P. aruensis Hentschel, 1912. Based on the description of P. amboinensis (Kieschnick, 1898), the shape and skeleton features exhibited by this species fit within the current diagnosis of P. bacca , therefore we recommend that these two species should be synonymized. The species P. lipotriaena was erected by de Laubenfels based on the absence of triaenes. Our examination of the type specimen (USNM 23049) revealed the presence of triaenes and the same characters as P. bacca , therefore we have synonymized this species with P. bacca. On the other hand, P. bacca can be distingished from P. corrugata Dendy, 1922, because of the abundant trichodragmata exhibited by the latter species. Consequently, P. corrugata can still be considered a valid species. Finally, the status of P. aruensis Hentschel, 1912 within this genus should be reconsidered. After examination of two slides available at the NHMUK, no calthrops were found, only the typical amphitriaenes originally described for this species. Amphitriaenes make this species more similar to the genus Amphitethya instead of Paratetilla . Further examination of specimens would corroborate our preliminary conclusion.

In a molecular phylogenetic study, which was based in part on specimens that we review in the current study (see Suppl. material 1, Table S1 for corresponding GenBank numbers), Schuster et al. (2017) distinguishes P. bacca as a monophyletic clade in the Tetillidae . Due to the wide distribution of this species and large intraspecific morphological variability we recommend further molecular studies, particularly of P. bacca from its type locality (American Samoa). This would allow a more detailed description of the genetic variation of P. bacca and verify our initial taxonomic proposal based on morphology.