Leucascus flavus, Cavalcanti, Fernanda F., Rapp, Hans Tore & Klautau, Michelle, 2013

Cavalcanti, Fernanda F., Rapp, Hans Tore & Klautau, Michelle, 2013, Taxonomic revision of Leucascus Dendy, 1892 (Porifera: Calcarea) with revalidation of Ascoleucetta Dendy & Frederick, 1924 and description of three new species, Zootaxa 3619 (3), pp. 275-314 : 297-299

Leucascus flavus sp. nov.

Etymology: Latin flavus : yellow. Describing the colour of the sponge alive.

Diagnosis: Colour alive is yellow. Spicules are slightly conical to conical, with sharp tips. Choanocyte tubes are hispid.

Type material: ZMAPOR 13145 (Holotype; Sulawesi, Bone Baku, Indonesia; station BB/NV/ 120597 /27; coll.: N. J. de Voogd; 16/V/1997; depth: 12 m).

Type locality: Sulawesi, Bone Baku, Indonesia.

Description: The colour of this specimen is yellow alive and beige after fixation ( Figure 14 A). The sponge measures 3.5 x 3.0 x 0.7 cm. The surface is smooth and the consistency is soft. The osculum was damaged, but it is possible to observe that there was no membrane or crown of spicules. A thin membrane covers the entire body. Below this membrane there are tightly anastomosed tubes and a wide atrium also lined by a membrane.

The skeleton is composed of triactines and tetractines. Both categories are present in the cortical membrane, but the triactines (both types) are more abundant ( Figure 14 B). Inside the cormus, slightly conical triactines and tetractines are present in equal proportions. The tetractines project their apical actine into the lumen of the choanocyte tubes ( Figure 14 C), which are slightly hispid. The atrial skeleton is composed of triactines and tetractines, but the tetractines are the most abundant spicules ( Figure 14 D).

Spicules ( Table 9 ):

(i) Triactines ( Figure 14 E, F): Regular. Actines are slightly conical or conical, straight, with sharp tips; (ii) Tetractines ( Figure 15 A): Regular. Actines are slightly conical. The apical actine is commonly straight, thinner than the basal actines, and ornamented with spines ( Figure 15 B).

Remarks: Leucascus roseus is most similar to L. flavus sp. nov. Both species present a cortical skeleton mainly composed of triactines and an atrial skeleton mainly with tetractines. Nevertheless, L. flavus sp. nov. is yellow alive, while L. roseus is pink. Other important differences between these species are the tip of the actines, sharp in L. flavus sp. nov. and blunt in L. roseus , and the choanocyte tubes, which are more hispid in L. flavus sp. nov.

Distribution: Indian Ocean. Sulawesi, Bone Baku, Indonesia. Spalding et al. (2007) corresponding ecoregion: Northeast Sulawesi.

Figures

FIGURE 14. Leucascus flavus sp. nov (ZMAPOR 13145, holotype). A, Preserved specimen; B, Cortical membrane; C, Apical actine of a tetractine projected into the lumen of a tube; D, Atrial membrane; E, Conical triactine; F, Slightly conical triactine.

FIGURE 15. Leucascus flavus sp. nov (ZMAPOR 13145, holotype). A, Tetractine; B, Apical actine of a tetractine with spines (SEM).

Tables

TABLE 9. Spicules measurements (µm) of the holotype of Leucascus flavus sp. nov.

Spicules	Actine		Length (µm)			Width (µm)		N
		Min	Mean SD	Max	Min	Mean SD	Max
Triactine		70.0	100.9 9.5	120.0	7.5	9.7 1.1	12.5	30
Tetractine	Basal	75.0	98.7 7.4	115.0	7.5	8.9 1.3	10.0	30
	Apical	41.3	49.6 5.3	60.7	3.6	4.2 0.6	4.9	30