Salacia tetracythara Lamouroux, 1816

Mendonça, Luana Marina de Castro, Guimarães, Carmen Regina Parisotto, González-Duarte, Manuel María & Haddad, Maria Angélica, 2021, First record of Salacia tetracythara Lamouroux, 1816 (Hydrozoa, Sertulariidae) as an alien hydroid for the Atlantic Ocean, Papéis Avulsos de Zoologia 61, pp. 1-7 : 3

Salacia tetracythara Lamouroux, 1816 ( Figs. 2 A-F, 3A-C)

Synonyms available in Bale (1884); Billard (1925); Watson (2000).

Material examined: Two infertile colonies – CZUFS CNI-00065 , 16.08 mm, sampled on 10 October 2017, depth of 4 m, rope 2, plates 1-2 ( Fig. 2A ) ; CZUFS CNI-00066 , 7.13 mm, sampled on 10 October 2017, depth of 4 m, rope 2, plates 5-6 ( Fig. 2B ). The colonies described in this paper were found on an artificial substrate. At the collection site, which was 16.4 km (straight line) from the TMIB port area, the water column was 4 m deep, the mean temperature was 26.5℃, pH 6.47,salinity 24.3 ppm, and dissolved oxygen 48 %.

Description: Colonies erect, 7.13 mm ( Fig. 2B ) and 16.08 mm ( Fig. 2A ) high, bearing alternating hydrocladia. Stems unbranched arising from a thick, short hydrorhiza, perisarc thick, two lateral rows of unconnected hydrothecae in subopposite pairs, three between successive hydrocladia (one inferior, one axillary and one opposite). Hydrocladia straight and rigid, on a single plane,alternating, branched once in two hydrocladia. One colony bearing tendrils on all hydrocladia (average: 1.16 ± 0.75 mm). Hydrothecae in two lateral rows in opposite to subopposite pairs, members of the same pair not in contact, but successive hydrothecae of a row in contact or overlapping. Hydrothecae tubular, adnate for nearly their entire length, slightly curved distally, aperture rounded, vertical with delicate margin showing signs of renovation, operculum composed of one oval valve attached to abcauline side. No teeth observed on margin. Adcauline wall of hydrothecae extended below by a triangular to ovoid adcauline space below each hydrotheca ( Fig. 2F ). Only one type of nematocyst was found, probably large microbasic mastigophores ( Fig. 3 ). Undischarged and discharged nematocysts were observed on stem and hydrothecae.The measurements are presented in Table 1.

Distribution: Australian tropical to temperate east and southeast coast ( Lamouroux, 1816; Bale, 1884; Watson, 2000), Indian Ocean (Kei Islands, Gulf of Aden) ( Rees & Vervoort, 1987; Schuchert, 2003), tropical and subtropical regions of Indo-Pacific (Albany Passage, Comoros, and Mascarene archipelagos, Off Cumberland Island, Fiji, Murray Island) ( Billard, 1925; Gibbons & Ryland, 1989; Gravier-Bonnet, 2008), China Sea ( Song, 2016).

Ecology: This species is mentioned mainly for the open ocean on mud with some radiolarians and globigerines, coral sand, coarse and fine sand with clay, small stones and shells ( Watson, 2000), on organic hard substrates of the outer slope of coral reefs and basaltic cliffs (Gravier- Bonnet, 2008). The colonies described in this paper were found on an artificial substrate, with hydrorhiza partially on Polychaeta tubes. The plates were S. tetracythara was found also had calcareous and membranous Polychaeta tubes, oysters, barnacles, bryozoans, and other hydroid species.

Figures

Figure 2. Salacia tetracythara Lamouroux, 1816, two colonies found in estuary of Sergipe River, northeast Brazil: CZUFS CNI-00065 (A) and CZUFS CNI-00066 (B). Details of first pair of hydrothecae from one hydrocladium of first colony (C). Details of second colony: terminal region of two hydrocladia showing tendrils (D); stem and three parts of hydrocladia (E); first pair of hydrothecae from one hydrocladium (F). Red arrows showing thin triangular to ovoid adcauline spaces.Scales: A = 5 mm; B = 2 mm;C = 200 µm; D-E= 500 µm;F = 100 µm.

Figure 3.Large microbasicmastigophore nematocysts undischarged and discharged (red arrow) found in polypbody (A,B)and coenosarc between hydrothecae on hydrocladia (C).Scales:A-C = 50 µm.