Leucascus roseus Lanna, Rossi, Cavalcanti, Hajdu & Klautau, 2007

Lanna, Emilio, Cavalcanti, Fernanda F., Cardoso, Lilian, Muricy, Guilherme & Klautau, Michelle, 2009, Taxonomy of calcareous sponges (Porifera, Calcarea) from Potiguar Basin, NE Brazil, Zootaxa 1973, pp. 1-27 : 5-7

Leucascus roseus Lanna, Rossi, Cavalcanti, Hajdu & Klautau, 2007

Synonyms. Leucascus roseus, Lanna et al. 2007: 1554 .

Type material. MNRJ 5827 (holotype /ethanol).

Type locality. Alcatrazes Archipelago, São Sebastião, São Paulo state, Brazil (24°06'S – 45°41'W).

Material examined. UFPEPOR 571, Urca do Tubarão, Guamaré, Rio Grande do Norte state (04º50’52.7”S – 36º27’02.1”W), depth: 8 m, coll. G. Muricy, 03/III/2007. UFPEPOR 614, Cabeço do Oliveira, Guamaré (04º53’10.9”S – 36º11’W), depth: 12 m, coll. L. Monteiro, 02/III/2007.

Other specimen examined for comparison: MNRJ 5827 (holotype), Alcatrazes Archipelago, São Sebastião, São Paulo state, Brazil (24°06'S – 45°41'W), depth 14 m, coll. E. Hajdu and M. Custódio, 2/V/2002.

Description. Sponge pink with or without white-ringed oscula in life and white to beige in ethanol. The largest specimen measures 8.5 x 8.0 x 8.0 cm. The cormus is massive and lobate, formed of tightly anastomosed tubes and covered by a thin and smooth membrane (Fig. 3A, B). Consistency is soft and fragile. Oscula are present on top of elevations and are surrounded by the same membrane that covers the cormus. Below FIGURE 3. Leucascus roseus (UFPEPOR 571). A— in situ photograph of a live specimen; B—transversal section of the cormus (cx—cortex, at —atrium); C—tangential section of the cortex; D—tangential section of the atrial wall; Edetail of an apical actine (arrow) projected into the lumen of a tube; F—triactine and tetractine.

each osculum there is an atrium without choanoderm, surrounded by a thin membrane. The aquiferous system is leuconoid. The skeleton is composed of triactines and tetractines. Triactines are the most abundant spicules of the membrane that covers the cormus (Fig. 3C), while tetractines are the most abundant spicules of the atrial membrane (Fig. 3D). Tube walls are composed of triactines and few tetractines. Consequently, most of them are smooth, although hispid lumens are also present (Fig. 3E).

Spicules ( Table 2). Triactines: equiangular and equiradiate. Actines are cylindrical and straight, with blunt tips [75.0–108.1 (±1.0)–129.0 / 11.8 (±0.1) µm (n = 2 specimens)] (Fig. 3F). Tetractines: equiangular and equiradiate. Actines of the basal system are cylindrical and straight, with blunt tips [72.0–100.6 (±0.6)–120.0 / 11.0 (±0.2) µm (n = 2 specimens)]. The apical actines are cylindrical, curved, with sharp tips [27.0–50.3 (±1.2)–90.0 / 4.8 (±0.1) µm (n = 2 specimens)] (Fig. 3F).

Min Mean s Max Mean s Triactine

UFPEPOR 571 75.0 107.1 10.0 129.0 11.7 0.9 30 UFPEPOR 614 87.0 109.0 10.0 123.0 11.8 0.8 30 All specimens 75.0 108.1 1.0 129.0 11.8 0.1 - Tetractine

UFPEPOR 571 basal 87.0 101.1 7.0 120.0 10.8 1.3 30 UFPEPOR 614 72.0 100.0 8.5 114.0 11.1 1.7 30 All specimens 72.0 100.6 0.6 120.0 11.0 0.2 - UFPEPOR 571 apical 30.0 49.1 7.9 66.0 4.7 0.8 30 UFPEPOR 614 27.0 51.4 14.4 90.0 4.9 0.8 30 All specimens 27.0 50.3 1.2 90.0 4.8 0.1 - Known distribution. Endemic from Brazil: São Paulo state (São Sebastião; Lanna et al. 2007). First record for Rio Grande do Norte state.

Ecology. Sponge photophilous, living on vertical substrata. Some specimens were associated to algae and hydrozoans.

Remarks. Only two species of Leucascus , L. roseus and L. simplex Dendy, 1892 , were previously reported from Brazil ( Borojevic & Peixinho 1976; Muricy et al. 1991). The skeleton of both species is composed of only one type of triactine and one of tetractine. Leucascus roseus differs from L. simplex by its pink colour, the cylindrical shape of its actines, the length of the apical actine of the tetractines (which is shorter in L. simplex ), and the higher abundance of tetractines in its skeleton. Leucascus roseus was previously recorded only from São Sebastião (São Paulo state), its type locality ( Lanna et al. 2007), located approximately 2,300 Km far from Potiguar Basin.

The abundance of tetractines in the external membrane was highly variable in L. roseus . In the specimen UFPEPOR 614, only one tetractine was found in the external membrane.