Paraleucilla magna, Klautau, Michelle, Monteiro, Leandro & Borojevic, Radovan, 2004

Klautau, Michelle, Monteiro, Leandro & Borojevic, Radovan, 2004, First occurrence of the genus Paraleucilla (Calcarea, Porifera) in the Atlantic Ocean: P. m a g n a sp. nov., Zootaxa 710, pp. 1-8 : 3-8

Paraleucilla magna sp. nov.

INSTITUTIONAL ABBREVIATION — MNRJ (Museu Nacional do Rio de Janeiro, Brazil).

TYPE MATERIAL — MNRJ 5147 (holotype / alcohol). Praia Vermelha, Rio de Janeiro, Brazil. Collected by E. Hajdu (11 / December / 2001), 4 to 5 m depth. ETYMOLOGY — From the Latin magna : “large”.

MATERIAL EXAMINED — MNRJ 3921, MNRJ 5186 (paratypes, Comprida Island, Cagarras Archipelago, collected by G. Muricy and L. Monteiro, 6 to 12 m depth); MNRJ 3814, MNRJ 3830, MNRJ 5163, MNRJ 5165, MNRJ 5181, MNRJ 5368, MNRJ 5510, MNRJ 5577, MNRJ 5577, MNRJ 5580 (Palmas Island, Cagarras Archipelago, collected by E. Hajdu, G. Muricy and L. Monteiro, 6 to 20 m depth); MNRJ 3873 (Laje das Cagarras, Cagarras Archipelago, collected by L. Monteiro, 6 to 12 m depth); MNRJ 7427; MNRJ 7430; MNRJ 7469 (Praia dos Anjos, Arraial do Cabo, collected by G. Muricy, 2 to 8 m depth); MNRJ 5831, MNRJ 5844 (Alcatrazes Archipelago, collected by U. Pinheiro and M. Carvalho, 16 m depth).

KNOWN DISTRIBUTION — Praia Vermelha, Urca, Cagarras Archipelago, Arraial do Cabo (Rio de Janeiro State); Alcatrazes Archipelago (São Paulo State) — Brazil. TYPE LOCALITY — Praia Vermelha, Rio de Janeiro, Brazil.

DESCRIPTION —The holotype is a massive specimen (more than 12 x 12 x 12 cm), white in life and in alcohol ( Fig. 2 A and B). The body has folds and oscula are located at the top of apical projections. There is no oscular fringe surrounding them ( Fig. 2 C). Below each osculum there is an atrium to which arrive some few canals. The surface is smooth. The aquiferous system is leuconoid and the choanocyte chambers are spherical, ranging from 56 to 112 m.

The skeleton is typical of the genus, being inarticulate near the surface (outer region) and without organization below the subatrial skeleton (inner region). The subatrial skeleton is not adjacent to the atrial skeleton, but it is followed by scattered large tetractines and some triactines similar to those of the subatrial skeleton ( Fig. 3 A). If the body wall is thin, the skeleton is only inarticulate ( Fig. 3 B). This condition can be observed in younger specimens or in younger (apical) parts of the sponge.

The cortical skeleton is composed of triactines and tetractines ( Fig. 3 C). Triactines are equiangular or, more frequently, sagittal. The size of the triactines is very variable. They lay tangentially to the surface, giving a smooth appearence to the sponge. The tetractines are large and their basal actines are almost equiangular. The apical actine is longer than the basal ones, and cross the choanosome. It runs parallel to the apical actine of the subatrial tetractines or, less frequently, to the unpaired actine of the triactines. While the apical actine of the cortical tetractines points toward the atrium, the apical actine of the subatrial tetractines and the unpaired actine of the subatrial triactines point to the surface.

The atrial skeleton is composed of sagittal triactines, with the unpaired actine shorter than the paired ones and penetrating the choanosome.

SPICULES. Cortical triactines: These spicules can be equiangular, but they are more frequently sagittal. Their size is very variable, and they lay tangentially to the surface. Actines are conical, with sharp tips ( Fig. 3 D).

Cortical tetractines: They are aproximately equiangular. The apical actine is longer than the others, centripetally directed, and it crosses the choanosome, being restricted to the outer layer in regions where the sponge body is thick but reaching nearly the atrium in the thin regions. Actines are straight or sometimes undulated with conical tips ( Fig. 3 E).

Subatrial tetractines and triactines: Differently from the cortical tetractines, the apical actine of the subatrial tetractines is shorter than the basal ones. The unpaired actine crosses the choanosome to the surface and it is shorter than the paired actines. The best way to differentiate this spicule from the cortical tetractines is by the shape of the paired actines ( Fig 3 F). The triactines are similar to them, but the shape of the paired actines is more similar to that of the cortical tetractines ( Fig 3 G). The unpaired actine also points to the surface, but it is frequently longer than the paired actines. Actines are slightly undulated, conical and sharp at the tips. These spicules are the same that compose the inner region.

Atrial triactines: These spicules are sagittal and have the unpaired actine shorter than the paired ones. Actines are conical, sharp, and frequently strongly undulated ( Fig. 3 H).

The micrometry of the holotype is presented in Table 1, and the micrometry of a paratype (MNRJ 3921) is presented in Table 2.

ECOLOGY — P. magna sp. nov. is the most abundant calcareous sponge in Rio de Janeiro State. The specimens are always attached to hard substrate, even when it is found on sand area. They live in photophylous and shaded environments, and were found from 0.5 to 20 meters depth. It seems to be resistant to pollution, having been found in clean waters but also in areas under strong influence of anthropic activities.

Length (m) Width (m)

Spicule Actines min mean max mean n

Cortical triactines Paired 168.0 292.8 71.2 408.0 24.0 4.8 30 Unpaired 176.0 289.6 75.2 424.0 24.0 5.6 30 Cortical tetractines Basal 224.0 434.4 89.6 568.0 34.4 7.2 30 Apical 184.0 468.8 104.0 640.0 31.2 5.6 30 Subatrial tetractines Paired 200.0 394.4 87.2 576.0 33.6 5.6 30 Unpaired 208.0 338.4 63.2 456.0 31.2 5.6 30 Subatrial triactines Paired 144.0 266.4 76.8 440.0 24.0 7.2 25 Unpaired 248.0 358.4 66.4 496.0 25.6 6.4 25 Atrial triactines Paired actines 240.0 371.2 53.6 456.0 22.4 4.0 30 Unpaired actines 80.0 164.0 48.8 328.0 21.6 3.2 30 Length (m) Width (m)

Spicule Actines min mean max mean n

Cortical triactines Paired 130.0 254.7 63.2 385.0 15.8 2.8 30

Unpaired 135.0 216.7 63.6 390.0 15.0 2.7 30 Cortical tetractines Basal 230.0 396.7 92.1 620.0 33.2 6.6 30 Apical 330.0 524.0 124.6 800.0 34.7 7.2 30 Subatrial tetractines Paired 290.0 381.3 57.8 500.0 32.0 4.8 30 Unpaired 200.0 300.7 62.9 420.0 31.3 5.2 30 Subatrial triactines Paired 210.0 297.1 93.0 450.0 22.1 6.8 30 Unpaired 180.0 330.0 114.8 600.0 22.2 6.9 30 Atrial triactines Paired 175.0 281.8 50.8 400.0 15.3 2.4 30 Unpaired 65.0 94.7 20.6 140.0 14.8 2.3 30 This species has a strong seasonality, being more abundant in summer and disappearing during autumn, to reappear as small individuals in winter. Several organisms were found associated to this species, such as: crustaceans, echinoderms and polychaetes. Starfishes of the species Echinaster brasiliensis (Müller & Troschel) were seen eating specimens of this species.

REMARKS — Of the 5 recognized species of Paraleucilla , only P. c u c u m i s, the type species of the genus, could be mistaken for our species. The known distribution of P. cucumis is Australia (Gulf of Saint Vincent and Bass Strait) and Sri Lanka (Palk Strait) ( Burton 1963). It is the only described Paraleucilla with triactines composing the atrial skeleton, all the other species having tetractines. P. magna sp. nov., however, can be easily differentiated from P. c u c u m i s by the form of the body, the absence of giant diactines at the surface, and by the presence of tetractines instead of just triactines in the cortical skeleton.

Until now the distribution of the genus Paraleucilla was restricted to the Indian Ocean and the Red Sea. Paraleucilla magna sp. nov. extends the distribution of the genus to the Atlantic Ocean. This species was first seen in Brazil (Rio de Janeiro) in the beginning of nineties, and since then it became the most abundant calcareous sponge, being in some places even the dominant sponge.

Figures

FIGURE 2. External morphology of Paraleucilla magna sp. nov. A — Sponge in situ; B — Preserved holotype; C — Detail of osculum and atrial cavity of holotype.

FIGURE 3. Internal morphology of Paraleucilla magna sp. nov. A — Cross section with disorganized layer; B – H holotype: B — Cross section without disorganized layer; C — Tangential section of cortex (tr — cortical triactines, te — tetractines); D — Cortical triactines; E — Cortical tetractine; F — Subatrial tetractine; G — Subatrial triactine; H — Atrial triactine.