Arturia, 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 : 25-26

Arturia (?) adusta ( Wörheide & Hooper, 1999)

Figures 5a–e

Clathrina adusta Wörheide & Hooper, 1999: 865 , figs 4D–H.

Ernstia adusta ; Klautau et al. 2013: 12.

Arthuria adusta ; Voigt & Wörheide 2016: 61

Clathrina aff. adusta ; Voigt et al. 2017: 5, fig. 3.

Material examined. ZMA Por. 10612, Seychelles, La Digue Island, S coast, 4.3833°S 55.8333°E, depth 2–8 m, snorkling, coll. R.W.M. van Soest, field nr . NIOP-E stat. 735/ 32, 23 December 1992.

Description. Cormus a small cushion ( Fig. 5a ), about 1 x 0.7 cm in lateral expansion, thickness 2–4 mm. Life color is unknown, in alcohol it is orange-yellow. Structure compact, made up of tightly anastomosed thin tubuli. No visible oscules. Consistency soft.

Aquiferous system. Asconoid.

Skeleton. ( Fig. 5b ) Wall of tubuli thin, consisting of one-two spicule layers with a prominence of triactines. The apical actines of the tetractines are protruding into the tubule lumina.

Spicules. ( Figs 5c–e ) Triactines and tetractines, the latter present in clearly smaller numbers. No distinct trichoxeas were found.

Triactines ( Figs 5c ) equiradiate and equiangular, with conical actines, some verging toward tripod-shape; actine sizes 48– 76 –108 x 6.5– 8.7 –12 µm.

Tetractines ( Figs 5d ) of similar shape and size to the triactines, actines of the basal triradiate system 54– 73 – 87 x 6.5– 7.6 –9.5 µm; apical actines ( Fig. 5e ) smooth, straight, sometimes with a slightly upturned apex, 39– 55 – 78 x 3 – 5.9 –7.5 µm.

Distribution and ecology. Egyptian Red Sea ( Voigt et al. 2017), Seychelles, NE Australia, on reefs in shallow depths.

Remarks. We base our identification largely on the sequence we obtained for our species, which ended up in a clade together with Voigt et al. ’s (2012) Australian sequence of Arturia adusta and Voigt et al. ’s (2017) Red Sea Clathrina aff. adusta (see his fig. 3). Klautau et al. (2013) had earlier assigned Clathrina adusta to Ernstia. Voigt & Wörheide (2016) discovered that this species falls outside the Ernstia clade and suggested that it should go to Arturia . We confirm that C. adusta is not an Ernstia, but with Voigt et al. (2017) we agree that assignment of C. adusta to Arturia s.s. is probably not correct, because Arturia sueziana and the type species of the genus Arturia , did not group in the same clade as C. adusta (see discussion above).

The present specimen resembles the type of Wörheide & Hooper (1999), although the white color cannot be affirmed. In glutaraldehyde the color of the type apparently changed to dark brown. Actine sizes 90–142 x 12–20 µm, more robust than in the Seychelles specimen, but overlapping. Voigt et al.’s (2017) record from the Red Sea mentioned actine sizes of 66– 73 x 9–10 µm, more similar to our specimen than to the type. The three sequences for these specimens differed only in a few sites (two between the type and the Seychelles specimen, three between the type and the Red Sea specimen).

Figures

FIGURE 5. Arturia (?) adusta (Wörheide & Hooper, 1999), ZMA Por. 10612, from the Seychelles, La Digue island, a, preserved habitus (scale bar = 1 cm), b, light microscopic image of cormus showing tight anastomosis of tubuli, c–e, SEM images of the spicules, c, triactines, d, tetractines, e, detail of apical actine of tetractine.