Reteporella sp. 1

Reteporella sp. 1

Figure 58 View FIGURE 58

Figured material. PMC EDM-Collection J.H.B.147a, sample 19015 ( Figure 58A–E View FIGURE 58 ) and sample 19025 ( Figure 58F–K View FIGURE 58 ); Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Description. Colony erect, rigid, non-fenestrate with dichotomous branching occurring at an angle of c. 60º; branches 410–750 µm wide, tri- to quadriserial, flat, and elliptical in cross-section. Autozooids arranged in alternating longitudinal rows, irregularly shaped, ranging from polygonal to flask-shaped to rounded/elliptical (mean ZL/ZW 1.35), covered by secondary calcification but remaining distinct, separated by raised margins, although it is uncertain if these boundaries correspond to the original margins of the autozooids. Frontal shield flat to slightly convex, faintly nodular, imperforate, except for 1–2 circular pores placed medially approximately at zooidal half length, 90– 135 µm from the orifice, with a diameter of 7–13 µm. Primary orifice deep, concealed by a short peristome proximally lodging the suboral avicularium on one side (the avicularium occupying about two-thirds of the proximal margin length), and forming a narrow (18–20 µm), U-shaped to drop-shaped pseudosinus, 30–35 µm deep, on the other side; secondary orifice semicircular; up to 6 robust oral spines, with 2–4 persisting in ovicellate zooids and/or when secondary calcification occurs; spine base 12–22 µm in diameter. Suboral avicularium constantly present, placed transversely in respect to the orifice, and directed laterally, or positioned slightly obliquely and directed proximolaterally, oval, with a slightly spatulate rostrum and a complete crossbar. Frontal avicularia seemingly absent. Ovicell globular immersed in secondary calcification but always leaving out a median longitudinal fenestra; a short labellum sometimes visible. Dorsal side nodular and pitted, with smooth, raised vibices outlining irregularly kenozooidal polygonal sectors of varying sizes, each sector with a few sparse circular pores, without avicularia. Measurements (µm). ZL 366±37, 314–464 (3, 18); ZW 271±46, 191–332 (3, 18); AvL 60±4, 54–71 (3, 18); AvW 44±5, 37–54 (3, 18).

Remarks. Among Reteporella species previously reported from Japan, R. obtecta (Buchner, 1924) is the only one with a similar suboral avicularium. However, it differs by having the rostrum projecting into the orifice (Harmer, 1934). Other Reteporella species from different regions of the world with similar suboral avicularium, such as the Mediterranean R. mediterranea Hass, 1948 and R. pelecanus Lopez de la Cuadra and Garcia-Gomez, 2001 , or R. tenuitelifera Canu and Bassler, 1929 and R. millespinae Canu and Bassler, 1929 from the Philippines, all differ by having fenestrate colonies or trabeculae with a greater number of zooids, numerous and variable frontal avicularia, or avicularia on the dorsal side (Canu and Bassler, 1929; Ramalho et al., 2018). We leave this species in open nomenclature due to the heavy secondary calcification, which prevents observation, description, and measurements of ovicells.