Clathrina maremeccae, 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 : 50-52

Clathrina maremeccae sp.nov.

Figures 25a–c

Material examined. Holotype, RMNH Por. 9662, Saudi Arabia, Jeddah , near Thuwal, Um Albalam, 22.193556°N 38.9475°E, scuba, coll. N.J. de Voogd, field nr. THU10/JED166, 12 November 2014.

Description. Cormus clathroid ( Fig. 25a ), forming a loosely anastomosed small mass of tubuli 0.2–1 mm in diameter leading to a few wider oscules. The single specimen is 15 x 8 x 4 mm in size. No evident water-collecting tubes. Color pale yellow, based on an on deck photo as there is no in situ photo.

Skeleton. ( Fig. 25b ) The tubule walls have a single layer of overlapping triactines.

Spicules. ( Figs 25c ) Equiradiate and sagittal triactines, with cylindrical actines, ending in often slightly swollen, blunt endings. Actines 67– 127.8 –165 x 5 – 6.4 –7.5 µm. A few broken trichoxeas are considered foreign.

Distribution and ecology. Saudian part of the Red Sea, on reefs.

Etymology. The name refers to the type locality, the Red Sea, which was named Mare Mecca by historical geographers (Wikipedia.org).

Remarks. The new species resembles Red Sea Clathrina rotundata Voigt et al., 2017 both in morphological aspects (loosely clathroid and with cylindrical actines of the triactines), and in a molecular sense as this species, based on partial 28SrRNA, also falls outside the larger clades of Clathrina species in our phylogenetic tree of Western Indian Ocean Clathrina species ( Fig. 2A ). However, there are also compelling reasons not to assign the present specimen to C. rotundata . Morphologically, the on deck photo shows a pale yellow color, whereas C. rotundata is white, and the upper actine length of the triactines is considerably higher than that of C. rotundata (165 vs. 123 µm). Molecularly, according to our phylogenetic analysis, the two species are not closely related. In a separate trimmed alignment of the two species of 382 sites length, C. maremeccae sp.nov. and C. rotundata differed in 49 sites.

There is considerable morphological similarity with Indonesian Clathrina beckingae Van Soest & De Voogd, 2015 , which has the same shape and tube diameter, colors also white and cream in various specimens, and equiradiate triactines with cylindrical actines. Differences are the presence of distinct water-collecting tubes and the absence of sagittal spicules in C. beckingae . Actine sizes of the triactines are also considerably smaller than those in C. maremeccae sp.nov. (up to 103 µm in C. beckingae ). We obtained partial 28srRNA sequences for this Indonesian material, and found that it differed in a separate trimmed 28S rRNA alignment of 382 sites length in 26 different sites.

No closely related species were identified in our partial 28SrRNA tree ( Fig. 2A ).

At the suggestion of one of the reviewers, we obtained an ITS sequence (not submitted to GenBank) for this species and in an analysis (not shown here) of ITS sequences of Clathrina species that appeared highly similar in a BLAST attempt, downloaded from GenBank, we noted that the new species ended up in a highly supported clade with Clathrin a sp. 4 and sp. 5 sensu Klautau et al. 2013, respectively a species from the Caribbean and from French Polynesia. A trimmed alignment of 556 sites of the three species showed 35 site differences between C. maremeccae sp.nov. and C. sp. 4, and 21 site differences with C. sp. 5.

Figures

FIGURE 2. Maximum-likelihood tree based on analysis of sequences of the partial 28S gene (C2–D2 region, comprising 442 sites) of Western Indian Ocean Calcinea 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. Please note that Arturia sequences do not appear in the same clade, indicating Arturia is non-monophyletic. Numbers at the root of clades are bootstrap values of 1000 replicates. Since the high number of sequences were difficult to read in detail, we subdivided the present tree in three detailed sections 2A, 2B, and 2C.

FIGURE 25. Clathrina maremeccae sp.nov., holotype RMNH 9662 from Saudi Arabia, Jeddah, a, habitus on deck (photo N.J. de Voogd), b, light microscopic image of the cormus, c, SEM images of triactines.