Kebira tetractinifera

Van, Rob W. M. & De, Nicole J., 2018, Calcareous sponges of the Western Indian Ocean and Red Sea, Zootaxa 4426 (1), pp. 1-160: 141-144

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Kebira tetractinifera


Kebira tetractinifera  sp.nov.

Figs 87a–d View Figure , 88a–f View Figure , 89a–e View Figure

Material examined. Holotype, ZMAAbout ZMA Por. 15245, South Africa, Port Elizabeth, Sea View, 32.9333°S 27.7°E, coll. A. van Schie, field nr. UPES 96–074, 6 February 1998.GoogleMaps 

Paratype, ZMAAbout ZMA Por. 13952, South Africa, Port Elizabeth , Cape Recief, coll. H. Engel, 20 November 1938  .

Description. A mass of upright tubular shapes, connected by flattened ridges. The holotype ( Fig. 87a View Figure ) is wet (alcohol preservation) and has a light beige color and a smooth surface. Size of the entire specimen is 3 x 2 x 2 cm, tubular individuals about 0.5 cm diameter. The paratype ( Figs 87b–c View Figure ) is a dried tubular individual of 4 cm high, pale yellow in color, with a broad base and a diameter of 1 cm, with atrial wall 2 mm thick and atrial cavity 5 mm in diameter. Consistency firm to hard.

Aquiferous system. Leuconoid.

Skeleton. ( Figs 87d View Figure , 88a–f View Figure ) In a cross section of the wall ( Figs 87d View Figure , 88a–c View Figure ), there is a cortical skeleton ( Fig. 88d View Figure ) formed by triactines with longer unpaired actines, carried by the pointed ends of perpendicular giant diactines, with only few of the diactines in a tangential position. The choanosomal skeleton is a dense mass of large triactines partitioned off by giant diactines and thin tracts of nail-shaped triactines (arrows in Fig. 88b View Figure ). The atrial skeleton is a layer of sagittal tri- and tetractines with short unpaired actines, with the apical actines of the tetractines protruding into the atrial cavity ( Figs 88c,e–f View Figure ).

Spicules. ( Figs 89a–e View Figure ) Giant diactines, nail-shaped triactines, triactines with long unpaired actines, triactines with short unpaired actines, tetractines with short unpaired actines.

Giant and smaller diactines ( Figs 89a View Figure ), fusiform, curved, 400– 904 – 1380 x 15 – 33.8 –45 µm.

Nail-shaped triactines ( Figs 89b,b View Figure 1 View Figure ), fusiform shaft, one end pointed, the opposite with conical or further extended short actines, arranged under a slight angle, often asymmetrical, unpaired actines 155– 249 –352 x 7.5– 9.7 –14 µm, paired actines 4– 14.5 – 40 x 4 – 7.5 –12 µm.

Triactines with long unpaired actines ( Figs 89c View Figure ), usually sagittal with paired actines similar in length or shorter, occasionally equiangular equiradiate; unpaired actines 156– 260 –355 x 10 – 15.4 –22 µm, paired actines 115– 182 –256 x 7 – 14.2 –20 µm.

Triactines with short unpaired actines and straight paired actines ( Fig. 89d View Figure ); unpaired actines 49– 76 –100 x 8 – 9.8 –12 µm, paired actines 155– 169 –195 x 7.5– 9.9 –11 µm.

Tetractines with short unpaired actines and straight paired actines ( Figs 89e View Figure ); unpaired actines 58– 82 –115 x 8 – 9.1 –10 µm, paired actines 126– 151 –181 x 7 – 8.9 –10 µm, apical actines 32– 43.6 – 50 x 6 – 7.6 –10 µm.

Distribution and ecology. Port Elizabeth region, Eastern South Africa, in shallow water.

Etymology. The name reflects the presence of sagittal tetractines, a feature distinguishing the new species from the type species, K. uteoides  .

Remarks. The possession of tetractines is the defining character of the new species, but the diactines differ from K. uteoides  in being shorter and thinner and not forming a thick cortical layer. Less definite is the difference in thickness of the triactines with long unpaired actines, with those of K. uteoides  being measurably thinner. See also below in the description of the Seychelles Kebira  specimen.

We obtained partial 28S sequences for the two Red Sea specimens of K.uteoides  and the holotype of K. tetractinifera  sp.nov. They grouped together in our Phylogeny of Fig. 3 View Figure with a high bootstrap value (94%). A separately investigated trimmed alignment of these three sequences, totaling 400 sites, showed four site differences between the two identical K. uteoides  sequences and the sequence of the new species.


Universiteit van Amsterdam, Zoologisch Museum