Sycettusa cf. hastifera (Row, 1909)

Azevedo, Fernanda & Klautau, Michelle, 2007, Calcareous sponges (Porifera, Calcarea) from Ilha Grande Bay, Brazil, with descriptions of three new species, Zootaxa 1402, pp. 1-22 : 16-19

Sycettusa cf. hastifera (Row, 1909)

MATERIAL EXAMINED—UFRJPOR 4937, UFRJPOR 4938, UFRJPOR 4939, UFRJPOR 4940, UFR­ JPOR 4941, UFRJPOR 4942, UFRJPOR 4943, UFRJPOR 4944, UFRJPOR 4945, UFRJPOR 4946, UFR­ JPOR 4947, UFRJPOR 4948, UFRJPOR 4949, UFRJPOR 4950, UFRJPOR 4951, UFRJPOR 4952, UFRJPOR 4953, UFRJPOR 4954, UFRJPOR 4955, UFRJPOR 4956. Angra dos Reis (Botinas Islands). Collected by M. Klautau & A. Rossi, 1 m depth.

KNOWN DISTRIBUTION—Red Sea, Indian Ocean, South Africa, Arraial do Cabo (Rio de Janeiro, Brazil).

COLOUR—Beige in life and in alcohol.

DESCRIPTION—The body is tubular with a single apical osculum surrounded by a fringe of trichoxeas ( Fig. 6 A). The atrium is smooth and central with several canals regularly distributed, as the aquiferous system is syconoid ( Fig. 6 B). The organization is typical of the genus, with an inarticulate tubar skeleton comprising the centripetal paired actine of the subcortical pseudosagittal triactines ( Fig. 6 C) and the unpaired actine of the subatrial triactines ( Fig. 6 E). The cortical skeleton is composed of triactines, and the surface is very hispid because of the presence of large diactines ( Fig. 6 D). The atrial skeleton is composed of triactines similar but shorter than those of the cortical skeleton ( Fig. 6 E).

SPICULES ( Table 11). Diactines: Slightly curved. The tip that protrudes through the surface is one side barbed, while the other tip is sharp ( Fig. 6 F).

Cortical triactines: Almost equiangular. The paired actines are slightly conical and sharp, while the unpaired actine is straight, conical and sharp. The paired actines are shorter than the unpaired one ( Fig. 6 G).

Subcortical triactines: Pseudosagittal. Actines are conical and sharp. The longest paired actine is straight (paired 1), while the shortest one is curved (paired 2). The unpaired actine is the shortest actine. Like in all pseudosagittal spicules, the paired 2 actine and the unpaired actine support the cortex, while the paired 1 actine points centripetally ( Fig. 6 H).

Subatrial triactines: Sagittal. The paired actines are conical, curved and sharp. The unpaired actine is conical and sharp, it points toward the surface, and it is longer than the paired ones ( Fig. 6 I).

Atrial triactines: Almost equiangular. They are similar to the cortical triactines in shape, but different in size. Their actines are shorter than those of the cortical skeleton ( Fig. 6 J).

Length Width

(µm) (µm)

Spicule Actines min mean S max mean S n

Diactines 302.5 679.0 193.2 1,025.0 20.0 4.4 25

Cortical triactines Paired 149.0 192.0 24.0 231.0 13.0 1.0 30 Unpaired 168.0 214.0 34.0 297.0 14.0 1.0 30

Subcortical triactines Paired 1 205.0 278.0 347.0 45.0 13.0 2.0 30 Paired 2 79.0 145.0 182.0 24.0 13.0 1.0 30 Unpaired 40.0 97.0 132.0 21.0 12.0 1.0 30

Subatrial triactines Paired 125.0 179.0 250.0 32.0 16.0 3.0 30 Unpaired 180.0 338.0 425.0 60.0 18.0 4.0 30

Atrial triactines Paired 125.0 153.0 188.0 17.0 9.0 1.0 30 Unpaired 99.0 144.0 191.0 27.0 10.0 1.0 30 REMARKS—The description of Sycettusa hastifera given by Row (1909) is not clear. He did not recognize the presence of pseudosagittal spicules in the subcortical skeleton, but differentiated two types of spicules forming the tubar skeleton: triactines and prochiacts. He considered that the former had paired actines of unequal length and were present in both subcortical and subatrial skeletons. On the other hand, prochiacts had the two paired actines of equal length and were the most abundant spicules in the tubar skeleton, being found mainly in the subatrial skeleton. We interpret that what Row called triactines of the tubar skeleton are pseudosagittal triactines, while what he called prochiacts are in fact the subatrial triactines. Independently of a possible misunderstanding on the spicules categories, our specimens are very similar to S. hastifera and can be differentiated only by the size of the spicules, which are larger in the Red Sea specimens ( Table 12). Considering the morphological similarity to S. hastifera from the Red Sea but also the tendency to endemism shown by calcareous sponges ( Solé­Cava et al. 1991, Klautau et al. 1994), we decided to call our specimens S. cf. hastifera , until species designation can be corroborated by molecular data.

Length Width (µm) (µm)

Spicule Actines

Diactines 1,000–1,100 30–40 Cortical triactines Paired 300 30–35 Unpaired 270–300 30–35 Subcortical and subatrial triactines Paired 1 320–350 30 Paired 2 200–300 30 Unpaired 100–120 25–30 Subatrial triactines “Prochiacts” Paired 100–120 25–30 Unpaired 400–450 25–30 Atrial triactines Paired 240 15–18 Unpaired 180–240 15–18

Figures

FIGURE 6. External and internal morphology of Sycettusa cf. hastifera. A—Preserved specimen; B—Longitudinal section showing the atrium; C—Cross­section showing the subcortical skeleton (arrow); D—Cross­section showing diactines protruding through the surface (arrow); E—Cross­section showing the subatrial skeleton (arrow); F—Diactine; G— Cortical triactine; H—Pseudosagittal triactines (u: unpaired actine; p 1: paired 1 actine; p 2: paired 2 actine).