Ircinia repens, Sandes, Joana & Pinheiro, Ulisses, 2014

Sandes, Joana & Pinheiro, Ulisses, 2014, Dictyoceratida (Porifera: Demospongiae) from Tropical Southwestern Atlantic (Northeastern Brazil, Sergipe State) and the description of three new species, Zootaxa 3838 (4), pp. 445-461 : 448-453

Ircinia repens sp. nov.

(Fig. 1–2; Fig. 3 ; Tab. 1–2)

Ircinia ramosa, sensu Boury-Esnault 1973: 289 .

Not Hircinia ramosa Keller, 1889: 345 ; Hircinia ramosa de Laubenfels 1934: 24; Hircinia dickinsoni de Laubenfels, 1936: 18; Ircinia ramosa , de Laubenfels 1948: 73; de Laubenfels 1950: 12, de Laubenfels 1954: 23, Hartman 1955: 164.

Type specimens. Holotype—MNRJ17619, off Pirambu (10º45’36’’S 36º36’08’’W), Sergipe State, Brazil, 20 m depth, coll. Cosme Assis and Damião Assis, July 2003. Paratypes: UFSPOR47, UFSPOR129, off Pirambu (10º45’36’’S 36º36’08’’W), Sergipe State, Brazil, 20 m depth, coll. Cosme Assis and Damião Assis, July 2003; UFPEPOR1622, off Pirambu (10º45’36’’S 36º36’08’’W), Sergipe State, Brazil, 20 m depth, coll. Cosme Assis and Damião Assis, July 2002; UFSPOR34, UFSPOR103, UFSPOR117, UFSPOR 152, off Aracaju (11º03’14.71’’S 36º54’52.36’’W), Sergipe State, Brazil, 30 m depth, leg. Petrobras, July 2002 (Fig. 1–2).

Diagnosis. Ircinia of ramose growth form, composed by repent branches and oscular projections.

External Morphology ( Fig. 3 A–B). Ramose shaped, composed of repent branches with pointed ends ( Fig. 3 A). The largest specimen is 18 x 2 cm (length x width). Conulose surface, with conules less than 1 mm high, 0.5–2 mm apart from each other. The oscular projections are up to 10 mm high ( Fig. 3 B) and irregularly distributed over the surface. The oscules have 2 mm in diameter. The consistency is compressible, elastic and easy to cut. Light to dark brown color in ethanol.

Skeleton ( Fig 3 C–E). The skeleton consists of a loose network of fasciculated spongin fibers, cored with foreign spicules and debris. The dermis is covered with an abundance of foreign debris. Primary fibers are125–215–287.5 µm wide and secondary fibers are 35–81–112.5 µm. The primary fibers are cored with more debris than the secondary fibers. Some secondary fibers aren’t cored ( Fig. 3 C–D). Collagenous filaments are 2.5–5 µm wide and occur in high density. Its expanded end is oval, 5–6.3 µm in diameter ( Fig. 3 E).

Ecology. The specimens were found 20–30 m deep and some of them were observed attached to coralline algae.

Geographical distribution. Tropical Southwestern Atlantic, Northeastern of Brazil, Bahia and Sergipe States ( Boury-Esnault 1973 and present study).

Etymology. The species name refers to its repent growth.

Remarks. The new species belongs in Ircinia due to the presence of fasciculated fibers cored with foreign debris and collagenous filaments. The presence of a dermal dusting of foreign debris is similar to Psammocinia . However, the massive fascicular fibers differentiate the new species from this genus, which makes Ircinia the best fit for the new species.

Of all species of Ircinia from the Tropical Western Atlantic, Ircinia repens sp. nov. is more similar to Ircinia ramosa , since both have ramose form (Tab. 1). This species was described by Keller (1889) and collected in the Red Sea, characterized by possessing a ramose growth form and thin collagenous filaments (2 mm thick), but its material type was unknown. De Laubenfels (1950) and Hartman (1955) reported this species to the Caribbean and Western Mexico, respectively. Their characterizations differ from the description of Keller (1889), mainly in the distance between conules, the thickness of collagenous filaments and the presence of a dermal dusting of foreign debris (Table 2). However, this latter feature is not reliable to separate these populations since the foreign debris in dermis might be a result of environmental conditions. De Laubenfels (1954) and Bergquist (1965) recorded I. ramosa for the Pacific Ocean and their characterizations were quite similar to the original description of Keller (1889). Bergquist (1965) noticed that I. ramosa from Pacific Ocean is co-specific with the Red Sea, and concluded that, due to the morphological differences and the great geographical distance between the Caribbean and these regions, the population of I. ramosa from Caribbean needed a new name.

Nevertheless, Boury-Esnault (1973) identified sponges collected in Brazil (Bahia and Sergipe State) as I. ramosa . Analyzing images of these specimens, we realized that the new species is co-specific with I. ramosa sensu Boury-Esnault (1973) , which differs from its congeners in the Tropical Western Atlantic in the presence of repent branches and oscular projections, whereas the population of I. ramosa from the Caribbean has vertical branches and absence of oscular projections (Table 1–2).

Even though the ramose growing form is a common characteristic I. ramosa , I. dickinsoni (de Laubenfels, 1936) and I. felix , I. repens sp. nov. differs from them because of the presence of repent branches and oscular projections. Additionally, compared to the new species, I. dickinsoni has higher and more widely spaced conules (1–2 mm high and 2–3 mm apart), no visible oscules and a spongy consistency, whereas I. felix has larger oscules (3–6 mm in diameter) scattered over the surface, and higher and more widely spaced conules (0.5–4 mm high and 1–6 mm apart).

Figures

FIGURE 3. Ircinia repens sp. nov. (A) Holotype (MNRJ 17619); (B) Oscular projection; (C) Fiber skeleton through transverse section highlight the dermis covered with foreign debris; (D) Reticulated skeleton of isolated spongin fibers; (E) Collagenous filaments. Scale bars: A, 1 cm; B, 3 mm; C – D, 205 µm; E, 21 µm.