Ascoleucetta sagittata, 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 : 308-309

Ascoleucetta sagittata sp. nov.

Etymology: Related to the sagittal triactines present in its skeleton.

Diagnosis: Skeleton composed of two categories of triactines and one of tetractines. Spicules are in general regular, but sometimes triactines become sagittal.

Type material: ZMAPOR 13283 (holotype; SW Sulawesi, Kudingareng Keke; field number KK/NV/ 130497 / 32; coll. N. J. de Voogd; 13/IV/1997; colour in vivo: yellow).

Type locality: SW Sulawesi, Kudingareng Keke, Indonesia

Description: Only a fragment of the type specimen was available. It has a smooth surface and is beige in alcohol ( Figure 21 A). The anastomosis is not evident, but in some regions it is loose. The atrium and osculum could not be observed. Cortical skeleton composed mainly of two categories of triactines, but tetractines are also present ( Figure 21 B). The large triactines are restricted to the cortex. Inside, small triactines and few tetractines are present. This last category of spicules points the apical actine into the lumen of the tubes, which are slightly hispid ( Figure 21 C). The atrial skeleton is composed of small triactines and tetractines, the former being the most abundant spicule type ( Figure 21 D). Sagittal triactines can be found in both cortical and atrial skeletons ( Figure 21 E).

Spicules ( Table 12 ):

(i) Cortical triactines ( Figure 21 F): Regular and large. Actines are straight, slightly conical, with sharp tips;

(ii) Triactines ( Figure 22 A): They are smaller than the cortical triactines and are frequently regular. Actines are straight, slightly conical to conical, with sharp (in the cortex) or blunt (in the atrium) tips. Some of them are sagittal, with curved paired actines, straight unpaired actine, and rounded tips ( Figure 21 E).

(iii) Tetractines ( Figure 22 A): Regular. Actines are slightly conical to conical, with blunt tips. The apical actine is short, thinner than the basal ones, and smooth ( Figure 22 B).

Remarks: Ascoleucetta sagittata sp. nov. can be easily differentiated from A. compressa and A. ventricosa mainly because of the absence of diactines (microdiactines and trichoxeas) in its skeleton. The third species of the genus, A. amitsba , differs from A. sagittata sp. nov. by the composition of the skeleton: A. amitsba presents three categories of triactines and two of tetractines, while A. sagittata sp. nov. has two categories of triactines and one of tetractines. Moreover, A. sagittata sp. nov. is the only species of the genus with sagittal spicules in its skeleton.

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

Figures

FIGURE 21. Ascoleucetta sagittata sp. nov. (ZMAPOR 13283, holotype). A, Fragment of the preserved specimen; B, Cortical membrane; C, Apical actine of tetractines projected into the lumen of a choanocyte tube; D, Atrial membrane; E, Sagittal triactine (arrow); F, Cortical triactine (arrow).

FIGURE 22. Ascoleucetta sagittata sp. nov. (ZMAPOR 13283, holotype). A, Choanosomal triactine (left) and tetractine (right); B, Apical actine of a tetractine (SEM).

Tables

TABLE 12. Spicules measurements (µm) of the holotype of Ascoleucetta sagittata sp. nov.

Spicules			Length (µm)		Width (µm)
	Actine	Min	Mean SD Max	Min	Mean SD Max	N
Cortical triactine		300.0	414.7 61.3 550.0	20.0	33.5 8.3 55.0	30
Choanosomal sagittal triactine	Paired	80.0	109.6 18.3 155.0	5.0	8.5 1.4 10.0	27
	Unpaired	85.0	114.6 14.4 140.0	7.5	8.7 1.3 10.0	23
Choanosomal regular triactine		110.0	137.7 12.4 160.0	10.0	12.1 1.6 15.0	30
Tetractine	Basal	110.0	129.0 9.0 150.0	10.0	11.3 1.3 12.5	30
	Apical	37.5	51.5 7.0 65.0	5.0	5.3 0.6 7.5	30