Ircinia sergipana, 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 : 446-448

Ircinia sergipana sp. nov.

(Fig. 1–1; Fig. 2 ; Tab. 1)

Type specimen. Holotype—MNRJ17618, off Pirambu (10º45’36’’S 36º36’08’’W), Sergipe State, Brazil, 20 m depth, coll. Cosme Assis and Damião Assis, December 2002 (Fig. 1–1).

Diagnosis. Ircinia with massive lobed form, conulose surface with projections up to 10 mm high and region between conules perforated by oscules.

External morphology ( Fig. 2 A–B). Massive lobed in shape, single specimen, 8 x 7.5 cm (width x height) ( Fig. 2 A). Conulose surface with projections up to 10 mm high and region between conules perforated by oscules smaller than 1 mm in diameter. The conules are 1–5 mm high, 3–5 mm apart ( Fig. 2 B). Consistency firm, elastic, easy to cut, and little compressible. Light beige color in ethanol.

Skeleton ( Fig. 2 C–D). The skeleton consists of a loose network of fasciculated spongin fibers with primary and secondary elements cored with foreign debris. Fibers are 35–82.8–130 µm wide and oval meshes up to 160 µm in diameter ( Fig. 2 C). Collagenous filaments are 2.5–5 µm wide and occur in high density. Its expanded end is a circle of 5–7.5 µm in diameter ( Fig. 2 D). Foreign spicules were also observed coring the fibers.

Ecology. The specimen was found at 20 m depth.

Geographical distribution. Tropical Southwestern Atlantic, Northeastern of Brazil, Sergipe State.

Etymology. The species name refers to the study area, Sergipe State.

Remarks. The family Irciniidae is characterized by spongin fiber skeletons supplemented with thin collagenous filaments. Ircinia is different from other genera of Irciniidae due to the presence of fascicular primary fibers, cored with foreign debris, and the absence of sand-armoured crust ( Cook & Bergquist 2002b). Even though the genus is easily recognized, the presence of a dermal dusting of foreign debris makes it difficult to differentiate Ircinia and Psammocinia Lendenfeld, 1889 . However, characteristics of fascicular primary fibers are useful in separating these groups, since Ircinia species have massive fascicular fibers, whereas Psammocinia species sometimes show moderate fasciculation with simple primary fibers ( Cook 2007). More difficult is the ability to consistently and clearly differentiate species of Ircinia due to uniformity of their internal morphology, habitat variability and surface characteristics. This difficulty makes ecological and morphological studies urgently needed in this genus ( Bergquist 1965).

Ircinia presently consists of 74 species, 13 of which occur in the Tropical Western Atlantic (Van Soest et al. 2014). Five of the species occur on the Brazilian coast: Ircinia campana (Lamarck, 1814) ; Ircinia felix ( Duchassaing & Michelotti, 1864) ; Ircinia pauciarenaria Boury-Esnault, 1973 ; Ircinia ramosa ( Keller, 1889) and Ircinia strobilina ( Lamarck, 1816) ( Muricy et al. 2011) .

Ircinia pauciarenaria was described by Boury-Esnault (1973) based on the presence of collagenous filaments of small thickness and small amount of foreign debris. However, when Muricy et al. (2011) proposed syntypes based on material from the Muséum National d' Histoire Naturalle (MNHN), they realized that the only two specimens identified as I. pauciarenaria were in fact not co-specific. Moreover, Moraes (2011) remarked that the species was a junior synonym of I. strobilina . We analyzed fragments of specimens and realized that the syntype MNHN 1012 actually corresponds to I. strobilina (see Muricy et al. 2011, p. 76, fig.7H). Thus, we designated MNHN 1022 as lectotype of I. pauciarenaria (see Muricy et al. 2011, p. 77, fig.8A).

The new species described here belongs in Ircinia because of the presence of collagenous filaments, the absence of dermal armour and fasciculate fibers cored with foreign debris. Traditionally, only the fasciculate primary fibers of Ircinia are cored by foreign debris. However, like Ircinia sergipana sp. nov., Ircinia felix sensu van Soest (1978) has both primary and secondary fibers cored. Also, it differs from Ircinia sergipana sp. nov. due to the presence of small conules (up to 4 mm high) and the absence of projections and oscules with dark edges.

Ircinia sergipana sp. nov. is set apart from its congeners in the Tropical Western Atlantic by reason of the combination of massive lobed growth form, the presence of projections up to 10 mm high and the region between conules is perforated by oscules. The only species that has conules up to 10 mm high is Ircinia strobilina . However, compared to the new species, it presents more widely spaced conules (5–15 mm) and no projections. Both species have visible oscules on the surface, but the oscules of I. strobilina are larger (4–10 mm in diameter) and always occur in groups, while the oscules of I. sergipana sp. nov. are less than 1 mm in diameter and distributed in the region between conules ( Fig. 2 B; Tab. 1). Ircinia sergipana sp. nov. shares the massive lobed form with I. pauciarenaria . However, it differs from the new species in the dark brown color, the absence of projections up to 10 mm high and the absence of a region between conules perforated by oscules. Moreover, I. campana also has large conules (up to 8 mm high) as for I. sergipana sp. nov., but differs from the new species due to its cup-shaped growth form (Tab. 1).

Figures

FIGURE 2. Ircinia sergipana sp. nov. (A) Holotype (MNRJ 17618); (B) Region between conules perforated by oscules; (C) Reticulated skeleton of isolated spongin fibers; (D) Collagenous filaments. Scale bars: A – B, 1 cm; C, 205 µm; D, 21 µm.