Kebira tetractinifera, Van & De, 2018

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

Kebira tetractinifera sp.nov.

Figs 87a–d , 88a–f , 89a–e

Material examined. Holotype, 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.

Paratype, 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 ) 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 ) 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 , 88a–f ) In a cross section of the wall ( Figs 87d , 88a–c ), there is a cortical skeleton ( Fig. 88d ) 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 ). 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 ).

Spicules. ( Figs 89a–e ) 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 ), fusiform, curved, 400– 904 – 1380 x 15 – 33.8 –45 µm.

Nail-shaped triactines ( Figs 89b,b 1 ), 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 ), 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 ); 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 ); 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 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.

Figures

FIGURE 1. Marine Ecoregions in the Western Indian Ocean with localities (numbered blue squares) from where the studied calcareous sponges were obtained. 1, Israelian Red Sea, Gulf of Aqaba, 2, Saudi Arabian Red Sea, off Jeddah, 3, Eritrean Red Sea, Dahlak Archipelago, 4, Oman, Gulf of Arabia, 5, Maldives, 6, India, Lakshadweep, 7, Seychelles, Mahé region, 8, Seychelles, Amirantes, 9, Mayotte, 10, Mozambique Channel, 11, Mauritius, 12, Rodrigues, 13, South Africa, Kwazulu Natal, 14. South Africa, Port Elizabeth, 15. Nosy Be, Madagascar.

FIGURE 3. Maximum-likelihood tree based on analysis of sequences of the partial 28S gene (C2–D2 region, comprising 461 sites) of Western Indian Ocean Calcaronea newly generated by the Naturalis Biodiversity Center and sequences additionally obtained from GenBank, the Sponge Barcode Project and from Oliver Voigt (München) from the Red Sea, Indonesia, Australia, and a few sequences from other parts of the world, to demonstrate the affiliation of the compared species. Numbers at the root of clades are bootstrap values of 1000 replicates.

FIGURE 87. Kebira tetractinifera sp.nov. from Eastern South Africa, a, habitus of holotype ZMA Por. 15245 (scale bar = 1 cm), b, habitus of paratype ZMA Por. 13952 (scale bar = 1 cm), c, detail of the same, d, light microscopic image of cross section of body wall of holotype.

FIGURE 88. Kebira tetractinifera sp.nov., holotype ZMA Por. 15245, SEM images of sections of the skeleton, a, cross section of body wall, b, detail of cross section of peripheral skeleton (arrows: tracts of nail-shaped triactines), c, detail of the cross section of atrial skeleton, d, overview from above of peripheral skeleton, e, overview from above of atrial skeleton, f, detail of the atrial skeleton with protruding apical actines of the tetractines with short unpaired actines.

FIGURE 89. Kebira tetractinifera sp.nov., holotype ZMA Por. 15245, SEM images of the spicules, a, giant and smaller diactines, b, nail-shaped triactines, b, details of nail-shaped triactines, c, triactines with long unpaired actines, d, triactine with short unpaired actine, e, tetractines with short unpaired actines.