Leuclathrina translucida Voigt et al., 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 : 70-73

Leuclathrina translucida Voigt et al., 2018

Figures 39a–f , 40a–c

Leuclathrina translucida Voigt et al., 2018: 151 , figs 2A–I, 3A–F.

Material examined. RMNH Por. 10072, Maldives, Faafu Atoll, Wallino, 3.087472°N 72.9567°E, depth 20 m, scuba, coll. N.J. de Voogd, field nr. MAD02 /MAS022, 16 February 2015 ; RMNH Por. 10090, Maldives, Faafu Atoll , Coral Garden, 3.0875°N 72.968861°E, depth 18 m, scuba, coll. N.J. de Voogd, field nr. MAD04 /MAS043, 17 February 2015 .

Description. In life, these sponges form pale yellow cushions ( Figs 39a–b, e ) consisting of dense layers of anastomosed thin tubes, from which issue long upright tubes. These long tubes are yellow at the base, but become transparent towards their ends ( Figs 39a–b ). The ends may be broadly flattened or occasionally bifid or curling downwards. The tubes are mostly closed but some are open and may function as oscules. The yellow base is ‘punctate’, i.e. there are regularly spaced rounded openings separating the tubes. On deck photos ( Figs 39c,f ) show the specimens to become uniformly yellow, while preserved specimens (3 in RMNH 1 0 0 72, 1 in RMNH 10090) become pale orange-brown all over ( Fig. 39d ). The size of preserved specimens is up to 4 x 3 x 1 cm, length of upright tubes 1–2 cm, width 3–4 mm, but the preservation has caused notable shrinkage, so in situ sizes are larger.

Aquiferous system. Leuconoid, not supported by spicules.

Skeleton. ( Figs 40a,b ) Thickness of tube walls consisting of two layers of overlapping triactines, or more than two layers in the upright long tubes. Insides of the bottom layer tubes and the basal parts of the long upright tubes ( Fig. 40b ) covered in yellow-colored organic mass, devoid of spicules, presumed to be choanoderm. The extent and thickness of this choanoderm precludes the tubes to be asconoid. This organic layer is absent from the end of the long tubes coinciding with the transparent parts observed in situ.

Spicules. ( Figs 40c ) Triactines only.

Triactines, equiradiate and equiangular, in a large size range, 101– 181 –243 x 8 – 13.1 –19 µm (RMNH Por. 10072: 101–238 x 8–19 µm, RMNH Por. 10090: 122–243 x 10–15 µm).

Distribution and ecology. Maldives, coral reefs

Remarks. This is a peculiar and deviating Clathrinida , assigned to Leuclathrina by Voigt et al. (2018) because of the presence of uniformly sized triactines at the surface with a choanoderm not supported by spicules. The 28S sequence we obtained (GenBank acc.nr. MF872789 ) grouped with Oliver Voigt’s sequence (nr. GW393) with 99% bootstrap value confirming the specimens belong to the same species. Because the affiliation of this species is rather uncertain, we included in our phylogenetic tree several sequences of possible close relatives ( Burtonulla , Ascandra , Levinella and Soleneiscus ). Although Leuclathrina translucida appeared indeed in the same clade as these genera (cf. Fig. 2B ), the bootstrap value is low, so none of the mentioned genera is likely close.

In the process, we made the discovery that the Indonesian Ernstia chrysops Van Soest & De Voogd, 2015 is apparently not an Ernstia but more likely an Ascandra .

So far, the position of Leuclathrina translucida in the molecular tree of Fig. 2 is outside and independent of the clades of Clathrina , Leucaltis, Ernstia and Leucetta . Ascandra species may have a rather similar habitus, but they have a majority and diversity of tetractines. Previously, Leuclathrina was monospecific and occurred in bathyal coral reefs off the coasts of Northwestern Europe. This second species is unlike the type species in shape, color and habitat.

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 39. Leuclathrina translucida Voigt et al., 2018, RMNH Por. 10072 and 10090 from the Maldives, habitus in situ, on deck and preserved, a–b, habitus in situ of RMNH Por. 10072, c, habitus on deck of RMNH Por. 10072 (both photos N.J. de Voogd), d, preserved habitus of RMNH Por. 10072 (scale bar = 1 cm), e, habitus in situ of RMNH Por. 10090, f, habitus on deck of RMNH Por. 10090 (both photos N.J. de Voogd).

FIGURE 40. Leuclathrina translucida Voigt et al., 2018, RMNH Por. 10072, from the Maldives, a, light microscopic image of surface skeleton, b, light microscopic image of a longitudinal cross section of a tube, showing surface cover of spicules and choanosomal soft parts, c, SEM images of the spicules.