Torquatella imperforata Yang, Seo & Gordon, 2018

Dick, Matthew H., Ngai, Nguyen Danh & Doan, Hung Dinh, 2020, Taxonomy and diversity of coelobite bryozoans from drift coral cobbles on Co To Island, northern Vietnam, Zootaxa 4747 (2), pp. 201-252 : 230

Torquatella imperforata Yang, Seo & Gordon, 2018

( Figs 13 A–D; 20C)

Torquatella imperforata Yang, Seo & Gordon, 2018, p. 509 , figs 29–31.

Material examined. VNMN-0251 (CT-10), VNMN-0252 (CT-21), on SEM stubs.

Measurements. AzL, 0.31–0.34 (0.322 ± 0.012); AzW, 0.17–0.25 (0.219 ± 0.024); OrL, 0.07–0.10 (0.088 ± 0.006); OrW, 0.08–0.11 (0.095 ± 0.009); OvL, 0.12–0.17 (0.145 ± 0.013); OvW, 0.14–0.20 (0.170 ± 0.018) (n = 12, 2).

Description. Colony small, encrusting, unilaminar, sheet-like.

Zooids small; distinct only toward colony margin; zooidal boundaries indistinct in colony interior. Frontal wall with four to six pseudopores and a few small, indistinct marginal pores; slightly convex, surface texture smooth, but with up to five or six conspicuous, coarse, irregular, haphazardly distributed nodules. Primary orifice slightly broader than long; anter semicircular, separated from broadly U- or rounded-V-shaped poster (sinus) by conspicuous, blunt condyles. Orifice completely surrounded by raised peristomial collar; collar cormidial, proximal half comprising raised frontal calcification proximal to orifice, distal half produced by frontal calcification from nextdistal zooid. Oral spines lacking.

Ooecium prominent but somewhat flattened in young zooids, later becoming subimmersed; imperforate; surface calcification smooth. Peristome continuing as raised flange along proximal ooecial margin.

Most but not all zooids bearing proximal suboral avicularium to right or left of midline inside peristomial collar, directed frontolaterally; face of rostrum concave; rostrum tapering and rounded-triangular proximally, blunt and raised distally; crossbar complete or incomplete; mandible semicircular.

Remarks. Yang et al. (2018) originally described this species from a single specimen from near Jeju Island off the southern coast of South Korea. The Co To specimens match the original description remarkably well, except that all measurements related to zooid size are nearly twice as great in the Co To specimens as in the Korean specimen. The average zooid length (0.179 mm) and range (0.13–0.25 mm) in length in the Korean study are unusually small for a neocheilostome bryozoan, and additional measurements from topotype specimens would eventually be useful. One of the Co To specimens has more pronounced frontal nodulation than the Korean specimen, although weak nodulation is evident in the latter.

Tilbrook (2006) erected the new monogeneric family Torquatellidae for the genus Torquatella , separating this genus from Celleporidae . Yang et al. (2018) argued against this change and recommended abandonment of Torquatellidae , which course we have followed here.

Distribution. The only previous record for this species was from near Jeju Island, South Korea, in the East China Sea ( Yang et al. 2018).

Figures

FIGURE 13. A–D. Torquatella imperforata Yang, Seo & Gordon, 2018. A. Colony, VNMN-0251. B. Orifice, VNMN-0251. C. Young autozooids with and without ooecia; arrowhead, suboral avicularium, VNMN-0252. D. Older autozooids with semiimmersed ooecia, VNMN-0252. E, F. Scorpiodinipora costulata (Canu & Bassler, 1929). E. Autozooids, VNMN-0254. F. Presumed ancestrula (arrowhead) and periancestrular zooids, VNMN-0255. Scale bars: A, 1 mm; B, C, 50 µm; D–F, 250 µm.