Leuconia pumila

Bowerbank, 1866

Species Overview

Leuconia pumila Bowerbank, 1866 are thin calcareous tubes with an even surface, not hispid. The consistency is firm. It may be distinguished from similar Leuconia species by the absence of oxeas (microscopic examination).

Taxonomic Description

Colour: White.
Shape, size, surface and consistency: Cylindrical, with optically smooth surface. Length up to 2 cm, diameter 5 mm. Apical oscule "naked" (no fringe). Consistency firm, fragile.
Spicules: (Leuconia pumila spics) Calcareous. Ectosomal triactines, regular to sagittal, in two size classes, rays: 600-1200 x 30-80 µm and 200-300 x 10-20 µm; choanosomal triactines similar to ectosomal triactines, likewise in two size classes. Atrial tetractines, sagittal, paired rays: 150-300 x 10-20 µm, basal rays: 250-350 x 10-20 µm, apical rays: 50-150 x 10-20 µm.
No oxeas.
Skeleton: (Leuconia pumila Haeckel) Ectosomal skeleton a layer of large and small triactines; choanosomal skeleton a mass of large and small triactines; atrial skeleton a tangential layer of tetractines.
Reproduction: July-August.
Ecology: Intertidal, under rocks; very common on hard bottoms in the sublittoral down to 12 m.
Distribution: Channel Islands, Roscoff, Iles de Glénan, coast of Spain; Mediterranean. Recorded from other regions and oceans, but these need confirmation.
Etymology: Pumilus (Latin) = dwarfish, small, referring to the size.
Type specimen information: Lectotype: BMNH: 1910.1.1.475 (dry), Norman Collection. Also 1 slide 1855.11.2.58a (Bk. 914) marked "type" and 3 other dry specimens 1855.11.2.58-60, all from Guernsey.

Remarks

Superficially similar to Aphroceras ensata , Leuconia aspera and L . fistulosa but these have oxeas among the spicules.
Source: Burton, 1963.