Leucandra mozambiquensis, 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 : 100-103

Leucandra mozambiquensis sp.nov.

Figs 60a–f , 61a–e

Material examined. Holotype, ZMA Por. 22408a, Mozambique Channel, between Mozambique and Madagascar, E of Juan de Nova Island, 17.2817°S 43.1567°E, depth 60 m, dredged, Pelagia Around Africa Exped.II, leg 6, field nr. 20 ASC 10, 1 April 2001.

Description. Irregular cup-shaped hollow mass ( Fig. 60a ) with undulating unequal lumpy walls, size 5 x 5 x 4 cm, walls approximately 1 cm thick. Color in alcohol pale brownish to dirty white. Surface rough. Inner surface of the atrial ‘hollow’ with a few oscular openings of 3–4 mm diameter. Consistency firm but fragile.

Aquiferous system. Leuconoid.

Skeleton. ( Figs 60b–f ) A cross section ( Fig. 60b ) shows a confused mass of spicules separated by a clearly developed cortical skeleton ( Figs 60c–d ) of smaller, mostly sagittal ‘oxhorn’ triactines and a clearly developed atrial skeleton ( Figs 60e–f ) of atrial tetractines. The choanosomal mass of spicules consists of giant triactines and smaller triactines. Near the atrial skeleton there are also sagittal subatrial tetractines recognizable by unpaired actine of length equal to the paired actines (whereas the atrial tetractines have shorter unpaired actines).

Spicules. ( Figs 61a–e ) Giant triactines, smaller triactines, atrial and subatrial tetractines.

Giant triactines ( Figs 61a ) of the choanosomal region, sagittal, usually with unpaired actine shorter than the paired actines, occasionally irregular with actines all of different lengths, actines relatively thin compared to other Leucandra species, 471– 903 – 1322 x 30 – 52.9 –72 µm.

Smaller triactines ( Figs 61b ) of the surface and the choanosome, not clearly differentiated, but either regular or more often ‘oxhorn’-like sagittal with curved and often slightly wobbly paired actines; unpaired actines 184– 258 –346 x 10 – 15.6 –26, paired actines 191– 348 –574 x 10 – 15.9 –34 µm.

Tetractines ( Figs 61c–d ), sagittal, with straight unpaired actines, straight or slightly curved paired actines, and straight or slightly curved apical actines, divisible into subatrially located tetractines with unpaired actines approximately as long as the paired actines, and proper atrial tetractines with unpaired actines clearly shorter than the paired actines.

Subatrial tetractines ( Fig. 61c ) with unpaired actines measuring 174– 221 –247 x 8 – 11.8 –15 µm, paired actines 187– 239 –298 x 11 – 12.6 –15 µm, apical actines 40– 55.6 – 73 x 5 – 6.7 –10 µm.

Atrial tetractines ( Figs 61d ) with unpaired actines 84– 108 –151 x 5 – 8.8 –12 µm, paired actines 210– 245 –289 x 6 – 9.2 –15 µm, apical actines 41– 62 – 92 x 5 – 6.3 –7 µm.

Distribution and ecology. Mozambique Channel, on continental platform of NW Madagascar, depth 60 m.

Etymology. Named after the type locality.

Remarks. By the absence of giant diactines, this elaborate species stands out among Leucandra species in the region. Only the above described L. pilula sp.nov. shares the lack of giant diactines, but that species has radically

different morphology and also the spicules have different dimensions (cf. above). The new species shows morphological similarities to NE Australian Leucandra nicolae Wörheide & Hooper, 2003 , which also lacks giant diactines and has elaborate shape, but that species has microdiactines lining the choanocyte chambers, which are not present here. The giant triactines of L. nicolae have shorter and thicker actines than the present material.

The tetractines of the subatrial region indicate a possible membership of the new species of the genus Leucandrilla (cf. below), because subcortical spicules in that genus include tetractines. However, the presence of the long-shafted tetractines in the present material is always close to the atrial skeleton, not in the subcortical region, and they are probably to be considered part of the atrial skeleton.

We obtained a partial 28S sequence of the holotype. In our Calcaronea phylogeny ( Fig. 3 ), the new species grouped together with L. pilula sp.nov. and L. nicolae at a modest bootstrap value (see also above under Remarks of L. pilula sp.nov.). The relationship with the other two species in the clade is not close.

The nearest group to Leucandra in our phylogeny ( Fig. 3 ) is Paraleucilla , currently assigned to the family Amphoriscidae . The general lack of sufficient 28S sequences of Calcaronea makes this position debatable. A separate inspection of the trimmed alignment of sequences of the clade of the three Leucandra species and the two Paraleucilla species (length 423 sites) showed 37 non-conserved sites indicating a large difference between the genera (see also below).

Figures

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 60. Leucandra mozambiquensis sp.nov., holotype ZMA Por. 22408a, from northern Mozambique Channel, a, preserved habitus (scale bar = 1 cm), b–f, SEM images of the skeleton, b, cross section (cortical skeleton above, atrial skeleton below), c–d, view of surface and detail, e–f, view of atrial skeleton and detail.

FIGURE 61. Leucandra mozambiquensis sp.nov., holotype ZMA Por. 22408a, from northern Mozambique Channel, SEM images of the spicules, a, giant triactines, b, cortical smaller triactines, c, subatrial tetractine, d, atrial tetractines.