Poricellaria ratoniensis ( Waters, 1887 )

Poricellaria ratoniensis ( Waters, 1887) View in CoL

Figure 16 View FIGURE 16

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

v. 1926 Poricellaria ratoniensis (Waters) ; Harmer, p. 134, pl. 17, fig. 14, pl. 23, figs. 3–8.

v. 1984 Poricellaria ratoniensis (Waters) ; Ryland, p. 70, fig. 39.21.

v. 2018 Poricellaria ratoniensis (Waters) ; Cook, Bock, Hayward and Gordon, p. 137, fig.

3.81.

Figured material. PMC EDM-Collection J.H.B.128a, sample 19085 ( Figure 16A–B, D View FIGURE 16 ) and sample 19048 ( Figure 16C View FIGURE 16 ); Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Description. Colony erect, flexible, articulated; branches narrow, 230–280 µm in width, quadriserial. Autozooids distinct, separated by thin furrows, asymmetrical, oval, elongate (mean ZL/ZW 2.24), arranged alternately in longitudinal rows. Gymnocyst well developed both proximally and laterally, smooth, convex. Mural rim thin, slightly elevated. Cryptocyst forming an extensive flat, slightly and asymmetrically depressed shelf mediodistally, rising proximal to orifice, nodular and smooth; a single slit-like opesiule, 77–88 µm long by 14–19 µm wide, positioned on the same side towards which the orifice inclines at the midpoint of the cryptocyst. Orifice semicircular, slightly wider than long, facing laterally, protruding from branch axis. Adventitious avicularia placed on the proximal gymnocyst, very close to the mural rim, salient; rostrum acutely triangular, narrow, long, channelled, directed proximolaterally almost transversely to branch axis, opposite to orifice; crossbar complete. Rhizoidal pore adjacent to avicularian rostrum tip, 5–9 µm in diameter, placed at the centre of a circular depression 29–37 µm in diameter. Ovicells not observed.

Measurements (µm). ZL 424±33, 380–472 (3, 13); ZW 189±16, 163–220 (3, 13); CryL 261±41, 199– 318 (3, 13); CryW 143±24, 108–176 (3, 13); GymL 146±20, 121–173 (3, 7); LatGymW 55±15, 36–77 (3, 7); OpL 57±4, 49–62 (3, 13); OpW 66±4, 61–73 (3, 13); AvL 105±20, 79–136 (3, 10); AvW 47±12, 36–67 (3, 10).

Remarks. Our specimens correspond to Poricellaria ratoniensis , a species extensively found across the Indo-Pacific. Previous records of P. ratoniensis have been documented in Indonesia (Harmer, 1926), Australia ( Waters, 1887; Ryland, 1984; Cook et al., 2018), New Guinea and Zanzibar (Cook et al., 2018), and the South China Sea (Gordon, 2016). Additionally, this species has also been recorded in the Miocene of southeastern Australia (Bock, 2024). To the best of our knowledge, this is the first record of this species in Japan.