Celleporaria cf. triangula Seo, 1994

Celleporaria cf. triangula Seo, 1994 View in CoL

Figure 56 View FIGURE 56

cf. 1994 Celleporaria triangula Seo , p. 189, pls.

1, 2.

cf. 2005 Celleporaria triangula Seo ; Seo, p. 397, pls. 120B, 121.

cf. 2017 Celleporaria triangula Seo ; Dick and Grischenko, p. 187, fig. 14f–h.

Figured material. PMC EDM-Collection J.H.B.146a, sample 19057; Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Description. Colony encrusting, multiserial, multilaminar. Autozooids distinct in the flat portion of the colony, separated by a thin raised rim, irregularly polygonal, irregularly arranged, longer than wide (mean ZL/ZW 1.36). Frontal shield convex, coarsely tubercular with rounded tubercles 12–18 µm in diameter, imperforate except for 2–4 rounded to elliptical marginal pores per side, approximately 10–30 µm in maximum diameter. Orifice wider than long (mean OL/OW 0.78), transversely D-shaped with concave proximal margin and three median denticles; the two lateralmost denticles triangular and delicate, the central one stout and rectangular, 8–12 µm long, delineating two small, rounded sinuses, one slightly wider than the other or the same size (16–18 µm and 16–16 µm in the only two preserved orifices measured); oral spines generally absent, a single spine observed in one of the distolateral orifice corners of three autozooids, spine base 14–20 µm in diameter. Peristome usually absent in young autozooids, with older autozooids developing a short, thick collar-like peristome not concealing the orifice. Adventitious avicularium single, suboral, placed on a cystid becoming more raised when the peristome develops, parallel to the proximal margin of the orifice, directed laterally, elliptical with complete crossbar, rostrum tip seemingly denticulate. Interzooidal avicularia randomly distributed and randomly oriented, placed on polygonal cystids coarsely granular with marginal areolar pores like the autozooids; rostrum seemingly rounded triangular or parallel-sided with complete crossbar. Ovicells not observed.

Measurements (µm). ZL 399±40, 358–449 (1, 7); ZW 293±41, 245–363 (1, 7); OL 114±2, 110–116 (1, 5); OW 147±9, 137–159 (1, 5); AvL (adventitious) 59±23, 43–75 (1, 2); AvW (adventitious) 45±1, 44–46 (1, 2); AvL (interzooidal) 162±9, 154– 171 (1, 3); AvW (interzooidal) 78±11, 69–90 (1, 3).

Remarks. The specimen of Celleporaria cf. triangula from Daidokutsu cave is poorly preserved and small, preventing the observation of all diagnostic characters of the species. Dick and Grischenko (2017), who recorded this species from a rocky-intertidal habitat on the west side of Okinawa ( Japan), listed several diagnostic features to distinguish C. triangula from other Celleporaria with similar orificial denticles: 1) one or two ephemeral spines, which we observed in two zooids of the colony fragment; 2) oral denticles delineating one micro- and one macro- sinus: in our specimen the denticles are preserved only in two zooids, and the sinuses appear to be more or less the same size, with one only slightly smaller; 3) interzooidal avicularia with blunt triangular mandibles: although the mandibles are not preserved in our material, the rostrum in two out of three observed avicularia appears rounded triangular, suggesting a similarly shaped mandible. One avicularium, partially obscured by cemented sediment, appears more parallel-sided; 4) the bluntly denticulate rostral margin of both adventitious and interzooidal avicularia is not clearly discernible. While it seems serrated, it is difficult to determine if this denticulation is genuine or due to breakage, given the preservational state of the specimen. Another difference is in the development of the peristome, which is only visible in three autozooids of our specimen.