Fig. 13L, M; Table 15
Sertularia leiocarpa Allman, 1888: 52, pl. 25 figs 1, 1a.
Sertularella leiocarpa. – Stechow, 1925: 477, fig. 35. – Galea, 2015: 9, fig. 3P.
Material examined: HRG-1056; Tristan da Cunha group of islands, E of Inaccessible I., -37.32000° 12.60000°, 160 m, coll. British Antarctic Survey, Stn. 80, lot DB12-0340; 24.05.2013; a ca. 5 cm high, sterile stem bearing a single side branch.
Description: Colonies up to ca. 7.5 cm high, arising from thin hydrorhizal fibers. Stems mono- or lightly polysiphonic basally, moderately stiff, giving rise to roughly alternate, coplanar side branches; stems and branches divided into moderately long, slender, geniculate internodes by means of indistinct oblique nodes; a hydrotheca confined to the distal end of each internode; side branches given off irregularly, directly (no apophyses present) and laterally from below a stem hydrotheca; up to 2nd order branches. Hydrothecae long, tubular, adnate for ca. 1/3rd their length to the corresponding internode, then curving gently outwards; abaxial wall almost straight, free adaxial wall slightly convex proximally, then nearly straight for most of its length; aperture facing outwards, provided with 4 small, triangular cusps separated by very shallow embayments; usually without intrathecal, submarginal cusps, but occasionally 2-4 present, one below each embayment; a 4-flapped operculum. Gonothecae arising from the stem internodes at level of hydrothecal bases, on opposite side to hydrotheca; spindle-shaped, walls entirely smooth, apically 3-4 short spines.
Dimensions: See Table 15.
Remarks: The colony shape and the gonotheca are illustrated by both Allman (1888) and Millard (1975). Although generally absent, internal, submarginal hydrothecal cusps may occasionally occur (Vervoort, 1966; Gili et al., 1989).
Distribution: Tristan da Cunha group of islands, Namibia, New Caledonia, New Zealand, as well as scattered records from the south and southeast Indian Ocean (Galea, 2015).