Smittoidea notoensis Hayami, 1975

Smittoidea notoensis Hayami, 1975 View in CoL

Figure 30 View FIGURE 30

v. 1975 Smittoidea notoensis Hayami , p. 114, pl. 16, fig. 8.

Figured material. PMC EDM-Collection J.H.B.132a, sample 19072; Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Description. Colony encrusting, multiserial, unilaminar. Autozooids distinct, separated by shallow grooves, elongate (mean ZL/ZW 1.68), rectangular to irregularly polygonal, seemingly arranged in alternating longitudinal rows. Frontal shield flat, slightly convex around the orifice, nodular, imperforate except for a single row of 13–15 (most commonly 15) circular to elliptical marginal areolar pores, 18–65 µm in maximum diameter, placed in deep, rounded quadrangular, funnelling depressions; an additional smaller pore, 12–18 µm in diameter, placed centrally below the avicularium. Primary orifice subcircular, almost as long as wide, with a rectangular lyrula occupying approximately one-third of its width; orifice surrounded by a short peristome developed proximally and laterally, forming two lateral flaps hiding condyles; secondary orifice keyhole-shaped, 100–110 µm long by 130–145 µm wide, with rounded triangular proximal constrictions; four distal oral spine bases, 20–28 µm in diameter, hidden in ovicellate zooids. Avicularium adventitious, single, suboral, median, embedded in proximal peristome with its distal margin adjacent to the base of lyrula, plectrum-shaped; rostrum rounded triangular, directed proximally; crossbar complete with a ligula outlining a slit-like opening distally and a transversely C-shaped opening proximally. Ovicell hyperstomial, globular, formed by the distal zooid, not closed by zooidal operculum; ooecium smooth, striated, densely and evenly pierced by 30–35 circular to elliptical pseudopores, with a maximum diameter of 9–27 µm, semilunar proximal margin imperforate, sloping inwards; secondary calcification spreading from adjacent zooids forming a narrow (25–50 µm wide distally, 35–55 µm laterally), nodular, peripheral perimeter.

Measurements (µm). ZL 613±37, 563–665 (1, 5); ZW 365±13, 351–386 (1, 5); OL 135 (1, 1); OW 137 (1, 1); AvL 52±5, 45–58 (1, 6); AvW 70±2, 68– 73 (1, 6); OvL 243±2, 242–245 (1, 3); OvW 292±6, 286–296 (1, 3).

Remarks. Smittoidea notoensis was previously known in Japan only as a fossil. The holotype was found in the Pleistocene Hiradoko Formation of Suzu City, while additional specimens have been discovered in the Pliocene Hamada Formation of Chikagawa and the Shibikawa Formation of Anden (Hayami, 1975). Our Holocene specimen matches the morphological description provided by Hayami (1975) and falls within the specified size range for ovicells, but has larger autozooids compared to those of the holotype (length 0.44–0.42 mm, width 0.24–0.32 mm).