Leucandra Haeckel, 1872

Borojevic, Radovan, Boury-Esnault, Nicole & Vacelet, Jean, 2000, A revision of the supraspecific classification of the subclass Calcaronea (Porifera, class Calcarea), Zoosystema 22 (2), pp. 203-263 : 224-225

Genus Leucandra Haeckel, 1872

TYPE SPECIES. — Sycinula egedii Schmidt, 1870 by subsequent designation (Dendy & Row 1913).

DIAGNOSIS. — Grantiidae with a sylleibid or leuconoid organization. Longitudinal large diactines, if present, are not restricted to the cortex, but lie obliquely across the external part of the sponge wall and protrude from the surface of the sponge.

DESCRIPTION

This is a very large genus containing many species ( Fig. 21 ). Initially it was defined primarily by negative characters, and included most of the leuconoid Calcarea. Dendy & Row (1913) narrowed the definition of the genus, and succeeded in giving it a more positive and circumscribed definition. In particular, they clearly perceived the difference between Leucetta and Leucandra , the first step required to separate a large group of leuconoid Calcinea from the genus Leucandra . In the present study we separate another group of leuconoid sponges, which have a particular skeletal organization and had been classified as Leucandra , into the order Baeriida . At the same time, following Jenkin (1908a) and BrØndsted (1931), we separate the sponges with thin walls and an inarticulate type of choanoskeleton into the family Jenkinidae , and following Dendy (1913), we separate grantiid sponges with tetractines in the cortical skeleton into the new genus Leucandrilla .

As pointed out by Dendy & Row (1913), Leucandra can be derived from grantiid sponges by a progressive substitution of the syconoid aquiferous system by a sylleibid or a leuconoid organization, and a concomitant replacement of the choanoskeleton of the tubes with a scattered one. Nonetheless, traces of the original radial organization are clearly preserved in the subatrial skeleton. Several authors have considered Leuconia Grant, 1841 as a senior synonym of Leucandra . As shown by Vosmaer (1887) and Dendy (1893), Leuconia has to be rejected, being previously used for a genus of mollusks. Leucandra Haeckel, 1872 being a valid synonym is the valid name of the taxon.

Leucandra has numerous representatives in all oceans.

Figures

FIG. 21. — A transverse section through the wall of Leucandra aspera (Schmidt, 1862) (light micrograph). Abbreviations: a, atrium; as, atrial skeleton; ch, choanosome; cx, cortex. Scale bar: 230 µm.