Poricellaria ratoniensis (Waters, 1887)

(Figs 2B, 4 A–C; Table 2)

Micropora ratoniensis Waters, 1887: p. 185, pl. 4, fig. 5.

Poricellaria ratoniensis: Harmer, 1926: p. 314, text-fig. 12, pl. 17, fig. 14, pl. 23, figs 3–8. TABLE 2. Measurements (µm) of Poricellaria ratoniensis (TAB 11). Min. Minimum; Max. Maximum; SE. Standard error; N. Sample size.

Material examined. TAB 11 from Stn JP 01-2.

Description. Colony erect (Fig. 4A), narrow (130–133 µm), dichotomously branched, stems narrow. Autozooids asymmetrical, oval, longer than wide (mean L/W = one-third), curved to face on one side of branch. Lateral walls gymnocystal. Cryptocyst extensive, deeply concave with a single opesiule (Fig. 4B). Adventitious avicularium (Fig. 4C) small, situated proximally on gymnocyst, with large subrostral chamber, rostrum acute, somewhat subtriangular, narrow, with hooked tip, oriented outwards.

Remarks. This is the only known Recent species of the genus, occurring in shallow waters of the Indo-West Pacific (Cook et al. 2018).

Distribution. Poricellaria ratoniensis was originally described from Papua New Guinea (Waters 1887), and later reported from Zanzibar (Waters 1913) and Indonesia (Harmer 1926).