Smittoidea ligata, Martino & Rosso & Taylor & Chiu & Fujita & Kitamura & Yasuhara, 2025

Genus SMITTOIDEA Osburn, 1952 View in CoL Smittoidea ligata sp. nov.

Di Martino, Rosso and Taylor

Figure 29 View FIGURE 29

zoobank.org/ 76B02F1B-D891-4C69-948B-CB3793409E93

Type material. Holotype PMC. B58. 29.7.2024 a, sample 19052 ( Figure 29A–D View FIGURE 29 ); paratype PMC. B58. 29.7.2024 b1, sample 19185 ( Figure 29E–F View FIGURE 29 ); paratype PMC. B58. 29.7.2024 b2, sample 19210 ( Figure 29G–H View FIGURE 29 ); paratype PMC. B58. 29.7.2024 b3,

sample 19044 ( Figure 29I–K View FIGURE 29 ); Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Etymology. Latin, meaning linked, referring to the raised rim linking the proximal peristomial pseudosinus to the avicularium.

Diagnosis. Smittoidea with autozooids separated by thin, raised sutures; nodular frontal shield with single row of marginal areolae, and additional pores around the avicularium; orifice with anvil-shaped lyrula occupying more than half of its width and acutely triangular condyles; peristome curved frontally with small marginal pores on its backside, forming a U-shaped pseudosinus proximally; 7–8 oral spine bases, 0–2 visible in ovicellate zooids; suboral avicularium teardrop-shaped, proximally directed, located a short distance from pseudosinus, connected to pseudosinus by a perpendicular suture; crossbar with blunt ligula; ooecium nodular and pseudoporous.

Description. Colony encrusting, multiserial, uni- to multilaminar. Autozooids distinct, separated by thin raised sutures of smooth calcification, elongate (mean ZL/ZW 1.53), oval to irregularly polygonal, irregularly arranged. Frontal shield flat to slightly convex, nodular, imperforate except for a single row of 10–18 (average 16) circular to elliptical marginal areolar pores, 14–45 µm in maximum diameter, placed in deep, funnel-like depressions; additional pores, 23–33 µm in diameter, placed around the avicularium, one on each side and one proximally. Primary orifice subcircular, almost as long as wide, with an anvil-shaped lyrula occupying more than half of its width (LyW/OW 0.66), with slightly downwardly curved tips; acutely triangular condyles directed medially or slightly downward, aligned with the lyrula distal margin; orifice surrounded by a short, tubular peristome, forming a Ushaped pseudosinus proximally; 7–8 (most commonly 8) oral spine bases, 14–26 µm in diameter, arranged in an arch, the proximalmost pair aligned with or slightly above the distal margin of the lyrula; 0–2 spine bases visible in ovicellate zooids, encased between the rim outlining the frontal shield and the rim of the projecting proximolateral margins of the ovicell; autozooids at colony edge with peristome curved frontally, its backside with small marginal pores. Avicularium adventitious, single, suboral, median, teardrop-shaped, positioned 15–50 µm from pseudosinus, connected to pseudosinus by a perpendicular raised suture of calcification; rostrum acutely triangular, directed proximally; crossbar complete with a small ligula outlining two elliptical openings, the smaller one distally. Ovicell hyperstomial, globular, formed by the distal zooid, not closed by zooidal operculum; ooecium smooth, striated (nodular if covered by secondary calcification), pseudoporous, with approximately 15 circular pores, 12–26 µm in diameter. Pseudoancestrula partially overgrown, resembling later autozooids but smaller, measuring approximately 248–366 µm in length by 212–224 µm in width, with 7–8 oral spines and an avicularium 69–89 µm long by 39–49 µm wide, surrounded by 4–5 autozooids slightly smaller than later ones, measuring 465–610 µm in length by 280–360 µm in width.

Measurements (µm). ZL 573±45, 527–625 (1, 5); ZW 374±66, 276–457 (1, 5); OL 114 (1, 1); OW 116 (1, 1); AvL 94±5, 87–100 (1, 10); AvW 49±5, 41–56 (1, 10); OvL 239±13, 225–250 (1, 3); OvW 323±35, 284–352 (1, 3).

Remarks. Smittoidea ligata sp. nov. differs from all Northern Pacific species described to date, including those reported from Japan. Considering the Japanese species: the Pleistocene Smittoidea reticulata ascoporoides ( Sakakura, 1935) differs in having significantly longer avicularia, measuring approximately 0.17 mm, and a pseudosinus that becomes a rounded pore separated from the proximal peristome (see also Kataoka, 1961); Smittoidea reticulata okadai Sakakura, 1938 , also from the Pleistocene, features similarly long and pointed avicularia; the Pliocene Smittoidea matobai Hayami, 1975 is distinct in that it lacks spines; and S. notoensis Hayami, 1975 is characterized by four distal spines that are consistently concealed in ovicellate zooids. Among the Smittoidea species documented from Sagami Bay by Hirose (2010): S. levis (Kirkpatrick, 1890) has the avicularium positioned adjacent to the proximal margin of the peristome, its ligula is better developed, and the orifice has a denticulate anter; S. pacifica ( Soule and Soule, 1973) differs in having an avicularium centrally located on the frontal shield, and a lyrula spanning nearly the entire length of the proximal margin. Hirose (2010) also identified two potential new species: Smittoidea n. sp. 1 stands out because of its narrower and deeper pseudosinus, absence of spines, and a distinct pattern of secondary calcification extending from the distal peristome to cover the proximal part of the ooecium, which is remarkably flat and embedded; Smittoidea n. sp. 2 is characterized by the lack of spines, a denticulate anter, and a larger avicularium that is differently shaped and positioned more proximally compared to the new Holocene species. In addition, the North Pacific species Smittoidea marginata (Canu and Bassler, 1929) , from the Philippines, has a long, narrow avicularium, which is more centrally located on the frontal shield.