Iotrochota cf. sinki Samaai Pillay & Janson, 2019

Calcinai, Barbara, Belfiore, Giuseppe, Pica, Daniela, Torsani, Fabrizio, Palma, Marco & Cerrano, Carlo, 2020, Porifera from Ponta do Ouro (Mozambique), European Journal of Taxonomy 698, pp. 1-56 : 37-38

Iotrochota cf. sinki Samaai Pillay & Janson, 2019

Fig. 20

Iotrochota sinki Samaai et al. 2019: 40 , fig. 16a–g.

Material examined

PONTA DO OURO • 3 fragments about 1 cm 3; 26°46′55.65″ S, 32°54′13.41″ E; Three Sisters; 24.2 m deep; 22 Mar. 2017; Cerrano leg.; PO85 • 1 single fragment 4.5× 2× 1 cm; 26°49′17.512″ S, 32°53′42.5″ E; Kev’s; 26.2 m deep; 22 Apr. 2017; Cerrano leg.; PO100 .

Description

Sponge massively encrusting or massive ( Fig. 20 A–B). On the surface, the exhalant system is evident as a vein-like pattern converging on the oscula ( Fig. 20B ). The color is yellow, mottled with brick red patches ( Fig. 20 A–B). In alcohol, the sponge changes its color to brown. Where the ectosome is preserved, the surface is smooth and the areolate surface still evident. The consistence is firm and incompressible.

SKELETON. The ectosome consists of a layer of compact smooth styles, easily detachable. The choanosome presents a reticulum of multispicular primary fibers, between 70 and 150 µm, with meshes up to 300 µm, and secondary multispicular fibers, 30–50 µm in section, with smooth, interstitial styles.

SPICULES. Styles ( Fig. 20C ), 140–(167, 14.8)– 195 µm ×5–(6.1, 0.8)– 7.5 µm, bent in the proximal part, closer to the head, the tips acerate or mucronate; thin and straight styles ( Fig. 20D ) 220–(232.5, 7.7)– 245 µm × 3–(4.5, 0.6)– 5 µm; less common and slightly curved, strongyles ( Fig. 20E ) 150–(170)– 190 µm ×5– (6.5)– 8 µm; birotulas ( Fig. 20F ) 12–(16, 1.3)– 17 µm.

Remarks

The specimens belong to the genus Iotrochota Ridley, 1884 , due to the structure of the choanosome with multispicular fibers and the presence of two different kinds of megascleres and birotulas. It comprises 15 species, with nine spread in the Indo-Pacific Ocean. Iotrochota nigra (Baer, 1906) was recorded in the same geographic area (East Africa), but differs in morphology and color, and, above all, in the absence of birotulas. Iotrochota baculifera Rildley, 1884 and I. purpurea (Bowerbank, 1875) are from the West Pacific Ocean, I. pella (de Laubenfles, 1954) and I. iota (de Laubenfels, 1954) are from Micronesia, I. protea (de Laubenfels, 1950) is from Hawaii, I. membranacea (Esper, 1794) is recorded in the East Pacific Ocean, I. coccinea (Carter, 1886) is from Australia. All these species are massive, dark violetblack colored and differ from the Mozambican specimens in spicule sizes and morphology. Iotrochota sinki , recently described by Samaai et al. (2019) from South Africa, perfectly matches the specimens from Mozambique, especially in the external morphology. Some differences are in the megascleres, as in I. sinki , styles in three size classes are recognized, and strongyles (that are considered rare) are longer (168–281 × 4 µm).

The species here described fits the description of Iotrochota birotulata (Higgin, 1877) , recorded many times in the Caribbean Sea and in Brazil ( Van Soest et al. 2019), in the general external morphology and its spicule features. Iotrochota birotulata shows a highly variable morphology, often erect, and is dark purple colored. The Mozambican specimens are characterized by the presence of two kind of styles (typical of the species of this genus) and strongyles are intermingled throughout the sponge; even the spicule dimensions fit those of the type species I. birotulata . Considering the disjunct geographic distribution of this record with respect to I. birotulata , it is convenient to identify the Mozambican species as Iotrochota cf. sinki Samaai et al. 2019 pending further molecular studies that could clarify its cryptogenic nature. The specimen PO85 ( Fig. 20A ) is in association with Zyzzyzus warreni Calder, 1988 (Class Hydrozoa, Phylum Cnidaria).

Figures

Fig. 20. Iotrochota cf. sinki Samaai et al. 2019. A–B. Massive (PO85) and encrusting (PO100) specimens in situ. C. Styles. D. Thin and straight style. E. Slightly curved strongyle. F. Birotula.