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Juxtacribrilina dobrovolskii n. sp. (Fig. 11; Table 4) urn:lsid:zoobank.org:act: C88EE938-BEEE-4FD3-B3B4-EBA40EEE38EA Diagnosis. Non-ovicellate zooids with 12–16 costae, 3 or 4 oral spines (predominantly 3); intercostal lacunae 6–9 in transverse series. Most zooids in basal layer with 1 or 2 frontal pore chambers on proximal gymnocyst. Ovicellate zooids occurring in basal layer, roughly same size (including ooecium) as non-ovicellate zooids; lacuna evident in midline at base of projection formed by suboral costae. Frontally budded dwarf ovicellate zooids occurring profusely in colony center; 4–7 costae (average 4.9); dwarf costal shield variable; tight, with wide, tapering costae and small intercostal lacunae, or reticulate, with narrow costae and very wide intercostal lacunae. Dwarf ooecium moderately reduced, cap-like, with a few irregular pseudopores; typically bearing single slit-like, oval, or ramifying pseudopore in midline. Etymology. Named for Dr. Andrej Alexandrovitch Dobrovolskij (1939–2019), Head of the Department of Invertebrate Zoology at Saint Petersburg State University, Russia, zoologist, protistologist, and parasitologist, specializing on Digenea. Material examined. Holotype and paratype: ZIRAS 01 /50733-A and -B, single pebble with one mature colony (holotype, A) and one ancestrular colony (paratype, B), Krabovaya Bay, Cape Severnyy Vkhodnoy, Shikotan Island, Lesser Kuril Chain (43.87722°N, 146.82000°E), collected by A.P. Tsurpalo, 28 August 1996; mid-intertidal, rocky shore; prepared for SEM examination. Measurements. See Table 4. Description. Colony (Fig. 11A) encrusting, multiserial, unilaminar except for frontally located dwarf zooids. Zooids (Fig. 11B–D) oval or spindle shaped, sometimes extended proximally; gymnocyst irregular, present as intermittent narrow band, widest at proximolateral corners (Fig. 11B, C), bearing 1 or 2 small, oval frontal pore chambers in most zooids. Frontal shield highly convex, sometimes slightly keeled; non-ovicellate zooids with 12–16 costae (average 14.5); intercostal lacunae circular, oval, irregular, or heart-shaped, 6–9 (average 7.5) in transverse series, each costa with minute lumen pseudopore at or near tip. In non-ovicellate zooids, suboral costae similar to or somewhat wider than others in width; ends of suboral costae often biramous, with more-distal pair of rami extending frontally or fronto-distally, meeting at midline to form projection proximal to orifice. Secondary orifice roughly semicircular, corners relatively sharp; 3–4 (average 3.1) articulated oral spines present; median one or two spines thinner than lateral spines, flattened, wider basally and tapering distally if single, cylindrical if paired. Ovicellate zooids abundant in basal layer (Fig. 11A, C), occurring in broad band five or six zooid generations wide between central region and margin, with ovicellate zooids again giving rise to non-ovicellate zooids at margin. Ovicellate zooids in basal layer with suboral costae markedly wider than rest (Fig. 11C), each with terminal lumen pseudopore; bifurcate at end, with more-distal rami meeting at midline to form broad, labiate flange directed fronto-distally and overhanging orifice; median lacuna at base of flange. Ooecial complex (Fig. 11C) with broad, thickened, non-articulated, modified latero-oral spines, each with near-terminal lumen pseudopore, arching toward and meeting at midline, twisted and narrower distally, often flattened and elevated, giving rise to wide, blunt, frontodistally directed flange. Secondary orifice of ovicellate zooids wider than long, with appearance of smiling mouth, flanked by proximal (suboral costae) and distal (latero-oral spines) labiate flanges. Ooecium likely kenozooidal, arising from roof of distal pore chamber; cap-shaped, broader than long, proximal edge overlain by modified spines but not visible in frontal view; with one to several irregular or ramifying pseudopores. Basal ovicellate zooids often in columnar series with other zooids. No. oral spines 3.1 (3–4) No. costae 14.5 (12–16) No. intercostal lacunae 1 7.5 (6–9) Ovicellate zooids, basal n = 7, 1 Zooid length 2 552 (495–685) Zooid width 294 (258–353) Orifice length 77 (47–99) Orifice width 180 (163–199) Ooecial complex length 146 (116–172) Ooecial complex width 234 (174–280) Ooecium length 62 (33–89) Ooecium width 172 (151–194) No. costae 12.0 (11–13) Frontal dwarf zooids n = 13, 1 Zooid length 2 317 (225–577) Zooid width 227 (178–357) Orifice length 80 (52–130) Orifice width 151 (117–231) Ooecial complex length 143 (95–231) Ooecial complex width 200 (138–312) Ooecium length 71 (52–111) Ooecium width 142 (112–215) No. costae 4.9 (4–7) 1 Number of lacunae in transverse series between second and third pairs of costae from orifice. 2 Includes the ooecium. Frontally budded dwarf zooids (11D, E) scattered abundantly in colony center; ooecial complex similar to that of larger, basal ovicellate zooids but with flanges proximal and distal to orifice less prominent; suboral flange comprising blunt or sharp "double" mucro formed from cylindrical, more-distal rami of suboral costae; distal, elevated flange on proximal margin of ooecial complex often lacking. Ooecium of dwarf zooids cap-like, kenozooidal, terminal, variable in size and shape, as wide as or wider than long; with one or two circular or elongate pseudopores in midline, or single ramifying pseudopore. Dwarf zooids with 4–7 costae (including suboral pair; average 4.9); costal shield either nearly flat, with wide, tapering costae and small intercostal lacunae, or markedly convex, inflated, with narrow costae and very wide intercostal lacunae forming a reticulate shield (both types evident in Fig. 11E). Ooecium sometimes with basal pore chamber distally (Fig. 11E). Only one reduced-size ovicellate zooid observed in basal layer—a dwarf zooid closer to colony center than to margin (not illustrated). One newly settled ancestrula observed (Fig. 11F); cribriform; tight shield composed of 14 costae; with 5 oral spines, median spine shorter and thinner than rest. Remarks. Juxtacribrilina dobrovolskii n. sp. differs from J. annulata in the same ways as do J. pushkini n. sp. and J. ezoensis n. sp.: most basal zooids bear one or two frontal pore chambers on the proximal gymnocyst; frontal dwarf zooids arise from these chambers and are often abundant and closely packed in the colony center; and the ooecium is cap-like and closely integrated with the modified latero-oral spines forming its proximal boundary. Juxtacribrilina dobrovolskii n. sp. differs most conspicuously from J. pushkini n. sp. and J. ezoensis n. sp. in features of the dwarf zooids. In J. dobrovolskii n. sp., the dwarf ooecium usually has a single irregular (slit-like, elliptical, or ramifying) pseudopore in the midline, and the costal shield bears 4–7 costae and is variable (Fig. 11E), either flatter with fewer costae, or more tumid, with the costae forming a reticulate shield. In the latter two species, the dwarf ooecium usually has two transversely arranged pseudopores, and the costal shield is either somewhat tumid, usually with 5 or 6 costae (J. pushkini n. sp.; Fig. 10A, B), or flatter, usually with 3 or 4 costae (J. ezoensi s n. sp.; Figs 4D, 6C). Basal zooids in both J. dobrovolskii n. sp. (Fig. 11C) and J. ezoensis n. sp. (Fig. 4A) have larger intercostal lacunae relative to costal width than J. pushkini n. sp. (Fig. 9A), and this is reflected in lower average numbers of intercostal lacunae in transverse series: 7.5, 6.9–7.5, and 8.2–9.0, respectively (Tables 2–4). Likewise, basal ovicellate zooids in both J. dobrovolskii n. sp. (Fig. 11C) and J. ezoensis n. sp. (Fig. 5C, D) tend to lack the distinct fold, seen in J. pushkini n. sp. (Fig. 9B), in each of the modified latero-oral spines contributing to the ooecial complex. Finally, the conspicuous median lacuna at the base of the flange formed by the suboral costae in basal ovicellate zooids in J. dobrovolskii n. sp. (Fig. 11B, C) is lacking in J. pushkini n. sp. (Fig 9B) and J. ezoensis n. sp. (Fig. 5B–D). Occurrence. Shikotan Island in the Lesser Kuril Chain is the only known locality for J. dobrovolskii n. sp., Published as part of Dick, Matthew H., Grischenko, Andrei V., Gordon, Dennis P. & Ostrovsky, Andrew N., 2021, The " Cribrilina annulata " problem and new species of Juxtacribrilina (Bryozoa Cheilostomata: Cribrilinidae) from the North Pacific, pp. 333-364 in Zootaxa 5016 (3) on pages 352-355, DOI: 10.11646/zootaxa.5016.3.2, http://zenodo.org/record/5222210

Exechonella similis C��ceres-Chamizo, Sanner, Tilbrook & Ostrovsky, 2017 (Fig. 6E, F) Exechonella similis C��ceres-Chamizo et al., 2017, p. 43, fig. 17. ? Exechonella brasiliensis: Winston & Heimberg 1986, p. 15, figs 26���27. Exechonella brasiliensis: Tilbrook et al. 2001, p. 65, fig. 8g. Material examined. VNMN-0226 (CT-24), on SEM stub. Measurements. AzL, 0.78���1.09 (0.930 �� 0.094); AzW, 0.52���0.80 (0.670 �� 0.074) (n = 15, 1). OrL, 0.18���0.21 (0.198 �� 0.012); OrW, 0.19���0.21 (0.203 �� 0.006) (n = 7, 1). Description. Colony encrusting, unilaminar, sheet-like. Zooids large, hexagonal, delineated by groove. Frontal shield convex, with minute areolae; perforated with 19���36 (29.7 �� 4.0; n = 13) foramina, each with smooth, raised rim. Orifice on average about as wide as long; with low, rounded condyles slightly proximal to middle; poster as wide as anter or nearly so, rounded-quadrate. Raised peristome surrounding orifice, slightly flared, smooth inside, pustulose outside, not obscuring orifice; often with low, blunt projection on proximal rim. Lateral-most foramen on one or both sides larger than rest, converted to avicularium, scarcely differentiated externally from other foramina. Oral spines, ooecia lacking. Remarks. C��ceres-Chamizo et al. (2017) described this species in detail, with excellent illustrations. Average zooid size at Co To (AzL �� AzW, 0.93 �� 0.67 mm) is larger than presented in the original description (0.78 �� 0.62 mm), but the number of frontal foramina is similar (19���36 at Co To vs 21���36 originally described). The original description states that the orifice is wider than long, but this is scarcely reflected in the accompanying measurements (OrL �� OrW, 0.19 �� 0.20 mm), and not at all at Co To (0.20 �� 0.20 mm). Distribution. The type locality is Lizard Island, Great Barrier Reef; this species is also known from Vanuatu (C��ceres-Chamizo et al. 2017). The previously known latitudinal range was 14��� 15��S; the Co To record extends the range northward nearly to 21��N., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on page 216, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Caceres-Chamizo, J. P., Sanner, J., Tilbrook, K. J. & Ostrovsky, A. N. (2017) Revision of the Recent species of Exechonella Canu and Bassler in Duvergier, 1924 and Actisecos Canu & Bassler, 1927 (Bryozoa, Cheilostomata): systematics, biogeography and evolutionary trends in skeletal morphology. Zootaxa, 4305 (1), 1 - 79. https: // doi. org / 10.11646 / zootaxa. 4305.1.1","Winston, J. E. & Heimberg, B. F. (1986) Bryozoans from Bali, Lombok, and Komodo. American Museum Novitates, 2847, 1 - 49.","Tilbrook, K. J., Hayward, P. J. & Gordon, D. P. (2001) Cheilostomatous Bryozoa from Vanuatu. Zoological Journal of the Linnean Society, 131, 35 - 109. https: // doi. org / 10.1111 / j. 1096 - 3642.2001. tb 01309. x"]}

Rhynchozoon lunifrons Dick & Grischenko, 2017 (Fig. 15) Rhynchozoon lunifrons Dick & Grischenko, 2017, p. 245, figs 37, 38. Material examined. VNMN-0262 ( CT-1), on SEM stub. Measurements. AzL, 0.40–0.62 (0.524 ± 0.073); AzW, 0.28–0.34 (0.309 ± 0.021); OrL, 0.10–0.11 (0.105 ± 0.005); OrW, 0.10–0.12 (0.106 ± 0.004); OvL, 0.16–0.19 (0.177 ± 0.010); OvW, 0.15–0.21 (0.189 ± 0.017); frontal AvRL, 0.076 –0.107 (0.092 ± 0.011); frontal AvRW, 0.031 –0.055 (0.050 ± 0.006) (n = 15, 1). Description. Colony encrusting, sheet-like, unilaminar at margin, multilaminar in older parts of colony due to frontal budding, but not becoming nodular. Zooids in marginal zone distinct; spindle-shaped or oval, delineated by groove; in older parts of colony, zooidal boundaries obscured; zooidal orientation haphazard in zones of frontal budding. Frontal shield in young zooids markedly convex, with three to five small areolae along each lateral margin; imperforate, texture smooth but surface slightly irregular. Orifice in marginal zooids parallel to frontal plane or tilted down distally, flanked by lateral flanges and sometimes low proximal projection. Primary orifice about as broad as long; with distinct, shallow, rather narrow, U-shaped median sinus; sinus flanked by sharp lateral projections that merge with fine diagonal ridges leading proximolaterally; low, rounded condyle between sinus and orificial rim on each side. Periphery of orifice distal to condyles beaded with 14–17 blunt denticles. Primary orifice sunken in low, D-shaped peristome; sharp rim around orifice distal to condyles. Oral spines lacking. Zooids in large parts of colony lack suboral or other avicularia. When present, suboral avicularium with rostrum longer than width of orifice, offset to one side or other, directed frontolaterally and also tilted toward distal end of zooid; crossbar complete; rostrum semicircular proximal to crossbar, long-triangular distal to crossbar, blunt or acute, slightly hooked at end, rostral plane straight or convex. Frontal avicularia developing primarily in secondary layers of colony; same size or somewhat smaller than suboral avicularia but similar in shape; usually along lateral or proximal margin, directed toward margin; usually one per zooid; chamber often raised, rostrum tilted frontally at angle of up to 45 degrees from frontal plane. Ooecium hyperstomial or sub-immersed, broader than long in frontal view, with extensive circular or semicircular window of non-calcified ectooecium, manifested as smooth endooecial layer when soft tissue removed; with or without narrow labellum along proximal margin of ooecium. Secondary orifice in older, haphazardly arranged zooids surrounded by up to four cylindrical projections that may arise from any of several surrounding zooids contributing to secondary orifice. Remarks. Features that identify this specimen as R. lunifrons include zooid and ooecium sizes similar to those in the original description (Dick & Grischenko 2017); the characteristic ooecium with a large, moonlike zone of smooth, exposed endooecium; the nearly circular orifice having a distinct, rather shallow U-shaped sinus; lack of oral spines; lateral and median processes flanking the orifice in both young and old zooids; relatively few, small areolae in marginal zooids; a large suboral avicularium oriented at a high angle to the frontal plane; frontal avicularia similar in shape to the suboral avicularia; and the development of cylindrical processes around the secondary orifice in older zooids, with these processes arising from two or more surrounding zooids. There are also differences with the specimens from Okinawa, the type locality and the only previously known locality for this species. In the Okinawa population, the marginal zone with well-delineated zooids having a relatively smooth frontal wall is much narrower, with zooids rapidly become coarsely pustulose, whereas in the Co To specimen, even the oldest zooids in the colony remain comparatively smooth.At Okinawa, the proximal orificial sinus is wider, without the sharp flanking projections leading to diagonal ridges, and the surrounding shallow peristome is not conspicuously D-shaped. Suboral avicularia are uncommon in the Co To specimen, and the highly raised avicularian chambers developing proximolateral to the orifice in marginal zooids were not seen. We conclude that the similarities outweigh the differences and that the two populations are conspecific, although examination of more material from Co To could alter this conclusion. Some of the differences observed between the two populations may be ecophenotypic; the specimens from Okinawa came from the rocky-intertidal habitat on a shore exposed to strong wave action, whereas the Co To specimen probably lived subtidally in a cavity and was not exposed to strong waves. Distribution. Previously known only from west-central Okinawa (Dick & Grischenko 2017).

Drepanophora gutta Tilbrook, Hayward & Gordon, 2001 (Fig. 7E, F) Drepanophora gutta Tilbrook, Hayward & Gordon, 2001, p. 74, fig. 10E, F. Drepanophora gutta: Gluhak, Lewis & Popijac 2007, p. 414, fig. 20A���C. Drepanophora cf. gutta: McCuller & Carlton 2018, p. 153, suppl. fig. S18C, D Material examined. One colony detected, VNMN-0227 (CT-33), on SEM stub with Celleporaria triangula. Measurements. AzL, 0.31���0.43 (0.370 �� 0.045); AzW, 0.20���0.32 (0.253 �� 0.035) (n = 13, 1). OrL, 0.085 ��� 0.087 (0.086 �� 0.001); OrW, 0.125 ���0.128 (0.127 �� 0.002) (n = 2, 1). OvL, 0.11���0.17 (0.137 �� 0.018); OvW, 0.16���0.20 (0.183 �� 0.014) (n = 9, 1). Description. Colony encrusting, unilaminar, sheet-like. Zooids small, variable in shape, distinct, delineated by shallow groove and 4���7 small, irregular marginal pores along each lateral margin. Frontal wall convex, imperforate, coarsely pustulose. Primary orifice broader than long but clearly visible only in marginal zooids; with conspicuous, broad, alate or truncate lyrula in midline. Mature zooids with primary orifice obscured by raised peristome having pustulose sculpturing like rest of frontal wall. Several oral spine bases observed, off-center, indicative of at least two oral spines. Most zooids with small avicularium in midline on proximal side of peristome, just below peristomial opening, mandible short-triangular, directed laterally to one side or other. Secondary orifice quadrate or irregular, sometimes with asymmetrical sinus between avicularian rostrum and small opposing peristomial projection. Ooecium hyperstomial, lying on frontal wall of next-distal zooid, surface smooth; ooecium bearing pair of peripheral foramina, one distolaterally on each side; imperforate centrally; peristome continues as collar around proximal edge of ooecium. Distribution. This species was originally described from a single colony found among coral debris at Port Vila Harbor, Efate, Vanuatu (Tilbrook et al. 2001). Gluhak et al. (2007) found it at Taiwan, and McCuller & Carlton (2018) reported it from Crook Point, Oregon, USA, on drift plastic presumably originating from Japan as the result of the 2011 tsunami., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on page 217, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Tilbrook, K. J., Hayward, P. J. & Gordon, D. P. (2001) Cheilostomatous Bryozoa from Vanuatu. Zoological Journal of the Linnean Society, 131, 35 - 109. https: // doi. org / 10.1111 / j. 1096 - 3642.2001. tb 01309. x","Gluhak, T., Lewis, J. & Popijac, A. (2007) Bryozoan fauna of Green Island, Taiwan: first indications of biodiversity. Zoological Studies, 46, 397 - 426.","McCuller, M. I. & Carlton, J. T. (2018) Transoceanic rafting of Bryozoa (Cyclostomata, Cheilostomata, and Ctenostomata) across the North Pacific Ocean on Japanese tsunami marine debris. Aquatic Invasions, 13, 137 - 162. https: // doi. org / 10.3391 / ai. 2018.13.1.11"]}

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).

Celleporaria triangula Seo, 1994 (Fig. 7 A���D) Celleporaria triangula Seo, 1994, p. 190, pls 1, 2. Celleporaria triangula: Dick & Grischenko 2017, p. 187, fig. 14f���h. Material examined. VNMN-0227 (CT-33), on SEM stub. VNMN-0228, three badly worn specimens. Measurements. AzL, 0.40���0.54 (0.465 �� 0.042); AzW, 0.28���0.41 (0.315 ��0.041); OrL, 0.10���0.13 (0.119 ��0.008); OrW, 0.13���0.16 (0.147 �� 0.010) (n = 15, 1). OvL, 0.17���0.21 (0.185 ��0.023); OvW, 0.21���0.27 (0.226 �� 0.020) (n = 4, 1). Description. Colony low, encrusting, multilaminar. Zooids distinct, delineated by groove; variably oriented with indistinct boundaries in layers other than basal layer. Frontal wall convex, imperforate, evenly coarsely pustulose, with three to seven small, circular areolae along each lateral margin. Orifice broader than long, D-shaped; proximal margin straight or slightly concave, irregular, typically with large and small sinus side by side, each bounded laterally by sharp projection, separated by sharp or truncate median denticle. Main oral sinus varies greatly in depth; sometimes scarcely evident. With age, primary orifice slightly sunken, surrounded by peristomial collar. Three or four short, ephemeral oral spines or spine bases evident in some marginal zooids. Small avicularium proximal to orifice, offset to one side or other of midline, on small chamber on peristomial collar, rostrum pointing frontolaterally or frontodistolaterally; mandible rounded, crossbar complete. Interzooidal avicularium large, with semi-elliptical mandible. Ooecium cucullate (hood shaped), with broad, semicircular opening. Remarks. Only a single non-worn specimen was obtained, which bore only one interzooidal avicularium. In zooid size, zooid morphology, shape of the interzooidal avicularium, and the shapes of (and variation in) the oral sinuses, this specimen greatly resembles specimens from Okinawa, Japan, reported as Celleporaria triangula by Dick & Grischenko (2017). However, zooids at Co To differ from both the Okinawa population and the Korean population originally described (Seo 1994) in having three or four rather than one or two short, ephemeral oral spines or spine bases evident in marginal zooids. The Korean population differs from those at both Co To and Okinawa in having deeper oral sinuses and wider, more pronounced median and flanking projections, and in having some of the vicarious avicularia narrower, almost lanceolate. Finally, in both the Co To and Okinawa populations, the fully formed cucullate ooecia appear to have the opening facing frontally, rather than oriented perpendicular to the colony surface and facing proximally. While these differences might indicate that the Okinawa and Co To populations are not conspecific with the Korean population, we retain the name C. triangula for all three, until more material can be examined from Korea southward. The variation in the proximal orificial margin within colonies at Okinawa and Co To mirrors to a great extent the variation that Harmer (1957, p. 674, text-fig. 56) illustrated for nominal C. aperta (Hincks, 1882). This latter species, however, both in the original description (Hincks 1882) and subsequently (Winston & Heimberg 1986; Ryland & Hayward 1992), has a single median oral sinus, very different from the condition in C. triangula. A significant proportion of the material Harmer (1957) attributed to C. aperta may actually be C. triangula or belong to a species complex that includes C. triangula. Distribution. Previously reported only from southern Korea and Okinawa, Japan., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 216-217, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Seo, J. E. (1994) Two species of Celleporaria (Cheilostomata: Bryozoa) from Korea. Korean Journal of Systematic Zoology, 10, 189 - 197.","Dick, M. H. & Grischenko, A. V. (2017) Rocky-intertidal cheilostome bryozoans from the vicinity of the Sesoko Biological Station, west-central Okinawa, Japan. Journal of Natural History, 51, 141 - 266. https: // doi. org / 10.1080 / 00222933.2016.1253797","Harmer, S. F. (1957) The Polyzoa of the Siboga Expedition, part 4, Cheilostomata Ascophora II. Siboga Expedition Reports, 28 d, 641 - 1147, pls. 42 - 74.","Hincks, T. (1882) Contributions towards a general history of the marine Polyzoa. IX. Foreign Cheilostomata (Miscellaneous). Annals and Magazine of Natural History, Series 5, 9, 116 - 127, pl. 5. https: // doi. org / 10.1080 / 00222938209459003","Winston, J. E. & Heimberg, B. F. (1986) Bryozoans from Bali, Lombok, and Komodo. American Museum Novitates, 2847, 1 - 49."]}

Hippothoa sp. (Fig. 5 D���F) Material examined. VNMN-0217 (CT-11; with Antropora minor), VNMN-0219 (CT-37; with Antropora minor), on SEM stubs. Material was limited, consisting of a single autozooid from one colony and six autozooids from another. Measurements. AzL (dilatation), 0.27���0.30 (0.288 �� 0.012); AzW, 0.16���0.19 (0.176 �� 0.013) (n = 7, 2). Cauda length, 0.394 ���0.527 (0.441 �� 0.075) (n = 3, 1). OrL, 0.059 ���0.071 (0.065 �� 0.008); OrW, 0.048 ���0.056 (0.052 �� 0.006) (n = 2, 1). Description. Colony encrusting, uniserial, branching. Branching pattern cruciform, with zooids giving rise to daughter zooids distally and laterally; daughter zooids arise laterally close to middle of dilatation or between middle and level of proximal edge of orifice. Zooids comprising long cauda expanding to form dilatation; cauda length 1.5���1.8 times length of dilatation. Dilatation highly transversely convex, oval in outline. Frontal wall gymnocystal, with faint transverse striation and slight median keel. Orifice nearly terminal, raised, oriented parallel to frontal plane, longer than broad, with deep, evenly U-shaped sinus flanked by sharp, bracket-like condyles; small pit at base of each condyle; no pit proximal to sinus. Spines, avicularia lacking. One zooeciule seen, arising proximolaterally from dilatation, unpaired, elongate opening comprising more than half zooeciule length (zooeciule incompletely developed?). Ancestrula, ooecium not observed. Remarks. This species was probably more abundant than our samples indicate, but was likely prone to loss by abrasion due to its small, widely separated zooids typically encrusting flat, open patches of substrate. Several species of uniserial Hippothoa having zooids with a long, narrow cauda occur in tropical and subtropical reef-rubble habitats, and the Co To specimens are not clearly identifiable with any of them. In Hippothoa flagellum Manzoni, 1870, zooids have only one lateral pore chamber and thus produces zooeciules in place of daughter zooids (Ryland & Gordon 1977), rather than additionally and proximolaterally. Hippothoa divaricata Lamouroux, 1821 var. pacifica Gordon, 1984 has the orifice tilted down distally rather than oriented in the frontal plane; there is a conspicuous median keel; and zooeciules are elongate, arising either laterally in place of daughter zooids, or proximolaterally. Hippothoa calciophila Gordon, 1984 is similar to the Co To specimens, but has a broader proximal orificial sinus with a pit proximal to the sinus, and larger condyles. Hippothoa petrophila Dick & Grischenko, 2017 is also similar to the Co To specimens, but has much longer caudae; more-conspicuous, rounded condyles; a pit proximal to the orificial sinus; and zooeciules with a small, circular opening. Key features we could not observe include the ancestrula and its budding pattern, the distribution of pores and pore chambers in the lateral and transverse walls, and the form of female zooids and ooecia. Identification of this species will require more material from the Co To vicinity., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 212-214, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Canu, F. & Bassler, R. S. (1929) Bryozoa of the Philippine region. United States National Museum Bulletin, 100, I-XI + 1 - 685.","Manzoni, A. (1870) Briozoi fossili italiani. Quarta contribuzione. Sitzungsberichte der Akademie der Wissenschaften in Wien, Abteilung 1, 61, 323 - 349.","Ryland, J. S. & Gordon, D. P. (1977) Some New Zealand and British species of Hippothoa (Bryozoa: Cheilostomata). Journal of the Royal Society of New Zealand, 7, 17 - 49. https: // doi. org / 10.1080 / 03036758.1977.10419334","Lamouroux, J. V. F. (1821) Exposition Methodique des Genres de l'Ordre des Polypiers, avec leur Description et Celles des Principales Especes, Figurees dans 84 Planches; les 63 Premieres Apartenant a 1 'Histoire Naturelle des Zoophytes d'Ellis et Solander. V. Agasse, Paris, 115 pp., 84 pls. https: // doi. org / 10.5962 / bhl. title. 11328","Gordon, D. P. (1984) The marine fauna of New Zealand: Bryozoa: Gymnolaemata from the Kermadec ridge. New Zealand Oceanographic Institute Memoir, 91, 1 - 198.","Dick, M. H. & Grischenko, A. V. (2017) Rocky-intertidal cheilostome bryozoans from the vicinity of the Sesoko Biological Station, west-central Okinawa, Japan. Journal of Natural History, 51, 141 - 266. https: // doi. org / 10.1080 / 00222933.2016.1253797"]}

Microporella tonkinensis n. sp. (Fig. 12 A–D) urn:lsid:zoobank.org:act: D8480B51-CC0D-4B7B-B038-581C87933ADC Etymology. The specific name comes from the Gulf of Tonkin, wherein lies the Co To island group. Material examined. Holotype, VNMN-0248 (CT-6); paratype, VNMN-0249 (CT-41); both on SEM stubs. Measurements. Holotype, VNMN-0248: AzL, 0.43–0.59 (0.513 ± 0.050); AzW, 0.28–0.48 (0.357 ± 0.051); OrL, 0.062 –0.074 (0.068 ± 0.003); OrW, 0.106 –0.124 (0.113 ± 0.005); OvL, 0.19–0.23 (0.207 ± 0.011); OvW, 0.23–0.27 (0.260 ± 0.011); AvRL, 0.090 –0.114 (0.102 ± 0.007); AvRW, 0.046 –0.063 (0.053 ± 0.006) (n = 15, 1). Paratype, VNMN-0249: AzL, 0.34–0.49 (0.428 ± 0.039); AzW, 0.23–0.38 (0.294 ± 0.043); OrL, 0.056 –0.072 (0.066 ± 0.004); OrW, 0.087 –0.104 (0.098 ± 0.005); AvRL, 0.068 –0.092 (0.082 ± 0.007); AvRW, 0.038 –0.057 (0.046 ± 0.005) (n = 15, 1). Diagnosis. Orifice with straight, weakly denticulate proximal margin; small condyles mediad to proximolateral corners of orifice. Modal number of oral spines four or five; spine bases often evident in zooids away from colony margin. Ascopore non-cribriform, without conspicuous umbo; pustulation between ascopore and orifice. Avicularia lateral or proximolateral to ascopore, one per zooid, small relative to orifice size. Non-personate, non-ribbed ooecium retaining pair of spines at proximolateral corners. Description. Colony unilaminar, encrusting, sheet-like. Zooids irregularly hexagonal, distinct, delineated by groove. Frontal wall markedly convex, with two to five small, inconspicuous areolae along each lateral margin; perforated over entire surface by small pseudopores, except in zone between ascopore and orifice; texture uniformly coarsely pustulose between pores; pustules usually present between ascopore and orifice, sometimes in discrete row. Orifice broader than long, broadly D-shaped, surrounded by low, smooth rim; proximal margin straight or slightly concave between conspicuous triangular condyles; condyles positioned slightly mediad to proximolateral corners of orifice; proximal margin weakly denticulate. Oral spines short, articulated; three (n = 5) or four (n = 27) in colony CT-6; three (n = 1), four (n = 13), five (n = 17), or six (n = 4) in colony CT-41; spines retained even in older parts of colony. Ascopore small, broader than long, encircled by smooth, raised rim, separated from proximal orificial margin by 1–1.5 times height of ascopore plus rim; with small lingula projecting proximally, leaving C-shaped opening; margin of opening finely denticulate all around. Sometimes proximal part of ascopore rim widened and raised as low, smooth tubercle. One avicularium per zooid, lateral to ascopore and directed distolaterally or sometimes laterally, or along zooidal margin proximolateral to ascopore, sometimes at lateral corner of zooid or even more proximally, directed distolaterally or laterally. Frontal avicularia moderately small, rostrum raised, sides and edges smooth, crossbar complete, area proximal to crossbar semicircular, mandibular area triangular, slightly longer than broad, guttered distally to allow for setiform mandible; setiform portion of mandible as long as or shorter than triangular rostral portion. Ooecium prominent, resting on frontal wall of next-distal zooid, broader than long, closed by operculum, with narrow, smooth, flat zone around proximal margin where operculum meets ooecium; with many small pseudopores around steep periphery, few in central-proximal area; top more finely pustulose than frontal wall, coarsely pustulose around periphery, with some moderately large marginal openings at base around distal margin; ooecium appearing peripherally ribbed at low magnification. Most-proximal pair of spines lateral to orifice retained in ooecium-bearing zooids, abutting proximolateral corners of ooecium. Remarks. Microporella is a speciose genus, with roughly 140 mostly Recent species described worldwide, from polar regions to the tropics (Bock 2018). The generic features are rather stereotyped, simplifying identification to genus but complicating identification to species. Until relatively recently, taxonomists viewed the European species M. ciliata (Pallas, 1766) as having a cosmopolitan distribution that essentially mirrored the range of the genus. While many species worldwide were correctly delineated from M. ciliata on the basis of unique apomorphies or combinations of characters, in the older literature many specimens from the tropical Pacific and elsewhere more or less similar to M. ciliata were attributed to that species, without description; for example, Canu & Bassler (1929) list M. ciliata from Hong Kong and the Philippines. Some of the characters utilized in the taxonomy of this genus are variable rather than discrete. For example, M. germana Dick & Ross, 1988 at Kodiak, Alaska, had three to five oral spines, with the modal number four, but at Ketchikan had four to six spines, with the modal number five (Dick et al. 2005). Similar interpopulation variation is seen in the frequencies of zooids having single, paired, or no avicularia per zooid, and in the shape of the ascopore (e.g., Harmelin et al. 2011, p. 18, fig. 9). One useful character that distinguishes one large group of species from another is the presence or absence of a personate ooecium (ooecium-bearing zooids have a raised peristomial rim, proximal and lateral to the orifice, that meets the ooecium distally) (Harmelin et al. 2011); M. dentilingua above has a personate ooecium, whereas M. tonkinensis n. sp. does not. Several similar species in the northwestern Pacific differ from M. tonkinensis n. sp. in the following ways. Microporella formosa Suwa & Mawatari, 1998 from Hokkaido, Japan, has larger avicularia relative to orifice size; the proximal orificial margin is smooth, with the condyles larger and occupying the proximolateral corners of the orifice. The orifice in Microporella antiborealis Liu & Liu, 2001 [listed in Liu et al. (2001) as previously described rather than as a new species, but we could find no reference for Liu & Liu (2001)] from China has a similarly finely denticulate proximal margin, but has larger avicularia relative to orifice size, a larger ascopore, and modal spine number six, and lacks the pair of lateral oral spines remaining at the proximolateral corners of the ooecium. Like M. tonkinensis n. sp., Microporella borealis Suwa & Mawatari, 1998 from Hokkaido, Japan, has a finely denticulate proximal orificial margin, and has four or five oral spines, retaining one pair at the proximolateral corners of the ooecium, but the condyles are larger and in the proximolateral corners of the orifice, the avicularia are much larger relative to orifice size, and there is no pustulation between the ascopore and orifice. Only two specimens of M. tonkinensis were found; these differed markedly in zooid size, with CT-6 having larger zooids than CT-41. This sort of variation seems to be common in tropical to subtropical cheilostomes, both within and between colonies; a similar case was observed in Rhynchozoon lunifrons Dick & Grischenko, 2017 at Okinawa. While some of this variation may be due to differences in temperature at time of growth (O’Dea & Okamura 1999, 2000), the degree of variation seems greater than occurs in cold-temperate faunas, and intercolony variation may require additional explanation. In any case, bryozoan taxonomists working in the tropics and subtropics should be aware that zooid size should be treated with caution as a taxonomic character. Distribution. Co To Island is the only known locality.

Bryopesanser tonsillorum Tilbrook, 2012 (Fig. 12E, F) Bryopesanser tonsillorum Tilbrook, 2012, p. 47, figs 17���22, table 1; and synonyms therein. Material examined. VNMN-0250 (CT-9), on SEM stub. Measurements. AzL, 0.52���0.76 (0.633 �� 0.066); AzW, 0.41���0.67 (0.482 �� 0.068) (n = 15, 1). OrL, 0.09���0.12 (0.108 �� 0.013); OrW, 0.103 ���0.123 (0.112 �� 0.011) (n = 4, 1). OvL, 0.12���0.15 (0.139 �� 0.010); OvW, 0.18���0.25 (0.218 �� 0.018) (n = 15, 1). Description. Colony encrusting, unilaminar, sheet-like. Zooids irregularly hexagonal, distinct, delineated by groove. Frontal wall convex, tumid, entirely perforated proximal to peristomial region with numerous small pseudopores. Primary orifice with horseshoe-shaped anter and deep proximal median sinus that is longer than broad; raised, coarsely denticulate condyles flank sinus, making proximal orifical margin convex. Non-ooeciate zooids with predominantly seven oral spines (eight seen in one zooid). Proximal to orifice, raised, imperforate, crescent-shaped ridge merging with chambers of lateral oral avicularia; ridge weakly flared around inside curvature; sometimes with raised median projection. Avicularia paired lateral to orifice; crossbar at roughly same level as most proximal pair of oral spines. Ooecium prominent, forming shallow cap distal to orifice, often with thickened, crescentic transverse ridge. Ooecium-bearing zooids showing three pairs of spines lateral to orifice, most distal pair incorporated in proximolateral margins of ooecium. Remarks. Species of Bryopesanser typically form small, inconspicuous colonies in crevices in coral-rubble substrata and are easily overlooked. With the raised condyles, convex proximal margin of the orifice, and deep oral sinus, B. tonsillorum is readily distinguished from several superficially similar congeners (Tilbrook 2012). Distribution. Broadly distributed; previously reported from the Atlantic (Ghana), Indian (Sri Lanka, Indonesia) and Pacific (Philippines, Columbia) oceans (Tilbrook 2012, and citations therein)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 228-230, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Tilbrook, K. J. (2012) Review of the bryozoan genus Bryopesanser Tilbrook, 2006 (Escharinidae: Cheilostomata) with the description of 11 new species. Zootaxa, 3165 (1), 39 - 63. https: // doi. org / 10.11646 / zootaxa. 3165.1.3"]}

Oncousoecia sp. (Fig. 19B) Material examined. VNMN-0271 (CT-42), on SEM stub with Tubulipora sp. Measurements. AzOr inside diameter, 0.11���0.16 (0.132 ��0.017) (n = 6). Ancestrular disk diameter, 0.264; ancestrular tube outside diameter, 0.159 (n = 1). Description. Young, ancestrular colony with 11 zooids; recumbent, zooids alternating in biserial lobes, though lobes perhaps wider later; peristomes not connate; exterior perforated by minute pseudopores. Zooidal orifices circular or transversely elliptical. Ancestrular primary disk circular, without pseudopores; ancestrula budding zooid distally and giving rise to another zooid laterally, apparently by peristomial budding. Remarks. Without a more fully developed colony and reproductive structures, this specimen can only tentatively be identified to genus Oncousoecia, and not at all to species., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on page 242, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740

Microporella dentilingua Tilbrook, 2006 (Fig. 11) Microporella dentilingua Tilbrook, 2006, p. 210, pl. 45E���F. Material examined. VNMN-0243 (CT-3), VNMN-0244 (CT-42), VNMN-0245 (CT-45), VNMN-0246 (CT-46), on SEM stubs; VNMN-0247, 23 dried specimens. Measurements. AzL, 0.52���0.60 (0.567 �� 0.023); AzW, 0.32���0.46 (0.378 �� 0.041); OrL, 0.070 ���0.081 (0.075 �� 0.003); OrW, 0.11���0.12 (0.116 �� 0.004); OvL, 0.21���0.32 (0.240 �� 0.026); OvW, 0.24���0.31 (0.281 �� 0.019); AvRL, 0.10���0.13 (0.117 �� 0.009); AvRW, 0.08���0.11 (0.092 �� 0.008) (n = 15, 1). Description. Colony encrusting, unilaminar, sheet-like. Zooids distinct, delineated by groove. Frontal wall moderately convex, with up to five small, slit-like areolae along each lateral margin; perforated over entire surface by numerous minute pseudopores; texture coarsely pustulose between pores. Orifice terminal, semicircular, broader than long; inside corners rounded, proximal margin straight, densely denticulate; orifice surrounded by smooth, raised rim. Usually three (n = 24) but occasionally two (n = 4) short, ephemeral oral spines present; if two, these placed either widely apart at distolateral corners of orifice, or closer together near midline. Ascopore rimmed; circular or wider than long, 1���1.5 ascopore lengths (including rim) distant from orificial rim; distal margin with moderately or extensively projecting lingula, leaving broadly or narrowly crescentic opening; opening finely denticulate all around. Avicularium single, large, nearly lateral or proximolateral to ascopore, directed distolaterally. Rostrum wide, raised distally at low angle from frontal plane; crossbar complete; narrowly semicircular proximal to crossbar, forming nearly equilateral triangular distal to it; distal end hollowed to accommodate setiform distal portion of mandible; lateral flaps lacking from setiform portion. Ooecium prominent, globose, as broad as long, texture densely pustulose, perforated by minute pseudopores; personate, with raised peristomial rim proximal and lateral to orifice; rim extends as ridge around proximal margin of ooecium, forming complete, slightly flared peristome. Remarks. With predominantly three oral spines, the ascopore relatively close to the orifice, the denticulate proximal orificial margin, the personate ooecium, and the large single avicularium proximolateral to the ascopore, the Co To specimens well match the original description of this species (Tilbrook 2006). One apparent difference is in the ascopore, which in many of the Co To zooids has a nearly circular outline almost completely filled by an extensive, nearly circular lingula projecting from the distal margin, leaving a narrow, distinctly C-shaped denticulate opening. However, there is intra- and intercolony variation in the ascopore in the Co To material, with some zooids having an ascopore that is broader than long, with a small lingula, leaving a wider, crescentic opening, as Tilbrook (2006, fig. 45F) illustrated for M. dentilingua. This local variation in the ascopore resembles that reported in geographically separate populations of Microporella harmeri Hayward, 1988 (Harmelin et al. 2011, fig. 9). In fact, M. harmeri greatly resembles M. dentilingua, but differs from the latter in having the ascopore farther from the orifice, and in having the avicularian mandible asymmetrically lanceolate in shape, with wing-like lateral expansions. Tilbrook (2006) mentioned a simple setiform mandible for M. dentilingua, as was the case for the Co To specimen that retained mandibles. Distribution. Previously known only from the Solomon Islands (Tilbrook 2006)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 225-227, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp.","Hayward, P. J. (1988) Mauritian cheilostome Bryozoa. Journal of the Zoological Society of London, 215, 269 - 356. https: // doi. org / 10.1111 / j. 1469 - 7998.1988. tb 04900. x","Harmelin, J. - G., Ostrovsky, A. N., Caceres-Chamizo, J. P. & Sanner, J. (2011) Bryodiversity in the tropics: taxonomy of Microporella species (Bryozoa, Cheilostomata) with personate maternal zooids from Indian Ocean, Red Sea and southeast Mediterranean. Zootaxa, 2798 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 2798.1.1"]}

Parasmittina parsevalioidea Liu, 2001 (Figs 8, 20D) Parasmittina parsevalioidea Liu, 2001 in Liu et al. 2001, p. 625, pl. 56, figs 1���4. Material examined. VNMN-0229 (CT-12), VNMN-0230 (CT-22), VNMN-0231 (CT-23), VNMN-0232 (CT-27), VNMN-0233 (CT-39), VNMN-0234 (CT-43), all on SEM stubs; VNMN-0235, 13 colonies and fragments. Measurements. AzL, 0.41���0.65 (0.504 �� 0.060); AzW, 0.24���0.39 (0.311 �� 0.044); OrL, 0.082 ���0.112 (0.096 �� 0.008); OrW, 0.083 ���0.102 (0.093 �� 0.006); OvL, 0.18���0.21 (0.193 �� 0.009); OvW, 0.19���0.24 (0.215 ��0.013) (n = 15, 1). Description. Colony encrusting, unilaminar, sheet-like. Zooids variable in shape (sub-rectangular, oval, spindle-shaped, irregularly polygonal), distinct, delineated by raised line of calcification between adjacent rows of marginal pores (circular, five to 10 along each lateral margin). Frontal wall slightly convex, imperforate, entirely coarsely pustulose. Primary orifice semicircular distally, widest at condyles; distal margin smooth; low, wide, non-alate median lyrula; strong, curved, tusk-like, acute, proximomedially directed condyles originating just proximal to widest part of orifice, finely denticulate along curved edge. Sharp peristomial lip surrounding orifice proximally and laterally, often forming raised lateral flanges. Oral spine bases, when evident, predominantly two, but occasional zooids with one, three, or four. Adventitious avicularia polymorphic, including the following types. 1) Small oral avicularium with short-triangular mandible, usually lateral to and directed toward orifice, tip of rostrum reaching top of peristomial flange, crossbar complete unless damaged; often degenerate, rostrum replaced by irregular opening; single, or often lacking. 2) Oval, shoe-shaped, or rounded-quadrate frontal avicularia, somewhat larger than oral avicularia, occurring proximally or laterally on frontal wall; one or occasionally two per zooid when present, lacking in many zooids; mandible short-spatulate, wider distally than proximally, pointing in any direction; crossbar usually incomplete but sometimes complete. 3) Large, spatulate avicularium originating lateral or distolateral to orifice, extending to lateral corner of zooid, directed proximolaterally; sides of rostrum parallel for about half rostral length, then expanding to spatulate end, about twice width of proximal portion; rim of rostrum smooth; large avicularia uncommon in Co To specimens and lacking in some colony fragments. Ooecium prominent, with about 25 pseudopores, imperforate in proximocentral area; periphery covered by narrow zone of pustulose frontal calcification from surrounding zooids; peristomial collar thickened, higher in ooeciate zooids, narrowing proximally as pseudosinus, extending part way onto ooecium on each side, occasionally forming complete collar across proximal part of ooecium. In reproductive parts of colony, large, secondary areolar openings surrounding peristome and ooecium, with calcified struts forming coarse reticular network. Remarks. The Co To specimens agree well with the original description of Parasmittina parsevalioidea Liu (in Liu et al.), 2001, from Hainan Island, China, roughly 200 km southeast of Co To. The original description notes that Parasmittina parsevalioidea varies in colony form from unilaminar to multilaminar, but we observed only the unilaminar condition in the colonies collected at Co To. Tilbrook (2006) declared P. parsevalioidea to be a junior synonym of P. galerita Ryland & Hayward, 1992, originally described from the Great Barrier Reef; however, while the two are very similar, they also appear to show consistent differences, and we retain the former name for populations in China and Vietnam. In P. galerita, the condyles are relatively small, blunt, and directed medially, with fine denticulation around the blunt end; in P. parsevalioidea, the condyles are long, tusk-shaped, acute, and directed proximomedially toward the lyrula, with denticulation along the curved edge. The lyrula in P. parsevalioidea appears to be wider than in P. galerita. In P. galerita, the peristome is complete around the proximal margin of the ooecium, whereas in P. parsevalioidea, short extensions of the peristome extend onto the ooecium but only occasionally meet to form a continuous peristome. Finally, the original description of P. galerita indicates that zooids have a single, ephemeral oral spine; spine number in our material ranges from one to four but most zooids have two, with spine bases remaining in older parts of the colony far from the margin. Nominal Parasmittina galerita from the Solomon Islands (Tilbrook 2006) has blunt condyles, one or two ephemeral oral spines, giant avicularia with the distal rim coarsely toothed, one or two triangular avicularia associated with each orifice, a triangular avicularium sometimes associated with the ooecium, and a flared peristome, and may represent a distinct species���in other words, nominal P. galerita may represent a complex of closely related species. Distribution. Previously reported from Hainan Island, China, at depths of 0���20 m (Liu et al. 2001)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on page 219, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Liu, X., Yin, X. & Ma, J. (2001) Biology of Marine-Fouling Bryozoans in the Coastal Waters of China. Science Press, Beijing, 860 pp., 82 pls.","Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp."]}

Scorpiodinipora costulata (Canu & Bassler, 1929) (Figs 13E, F; 20A, E) Schizoporella costulata Canu & Bassler, 1929, p. 317 (part), pl. 36, fig. 10; not pl. 36, fig. 11. Scorpiodinipora costulata: Harmelin et al. 2012, p. 127, figs 1���5, and synonyms therein; Taylor & Tan, 2015, p. 29, fig. 15G���I. Material examined. VNMN-0253 (CT-18), VNMN-0254 (CT-19), VNMN-0255 (CT-23), on SEM stubs. Measurements. AzL, 0.36���0.51 (0.423 �� 0.035); AzW, 0.23���0.37 (0.270 �� 0.043); OrL, 0.12���0.15 (0.139 �� 0.008); OrW, 0.09���0.11 (0.095 �� 0.007) (n = 15, 1). Description. Colony unilaminar, encrusting, sheet-like. Zooids small, oval in outline, distinct, delineated by groove. Frontal shield imperforate, with short costate ridges around periphery; with small, circular marginal pores between bases of ridges. Orifice subterminal, elongate, equally rounded proximally and distally, separated into anter and poster by pair of rounded condyles near middle; orifice surrounded by distinct, raised orificial rim. Oral spines, avicularia, and ooecia lacking. One ancestrula observed; similar in morphology to later zooids, but smaller, with proportionally smaller orifice; budding pattern affected by local impediment, unclear. Remarks. Harmelin et al. (2012) redescribed S. costulata, clarified synonyms, and revised the known global distribution. They treated this species as a case study relevant to a number of other species (e.g., Antropora minor above) having global distributions encompassing allopatric populations showing minor morphological differences from one another, raising the question whether these broad distributions reflect broadly distributed species complexes, or are the result of anthropogenic dispersal from a native source locality via floating debris or ships, or a combination of both. Distribution. Circumtropical in distribution; reported from the southwestern Atlantic, Caribbean Sea, eastern Atlantic, Indian Ocean, Red Sea, southeastern Mediterranean Sea, and western Pacific (Harmelin et al. 2012, and citations therein). In the Pacific, known from the Philippines (Canu & Bassler 1929), Malaysia (Taylor & Tan 2015), and Vietnam (this study)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 231-232, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Canu, F. & Bassler, R. S. (1929) Bryozoa of the Philippine region. United States National Museum Bulletin, 100, I-XI + 1 - 685.","Harmelin, J. - G., Vieira, L. M., Ostrovsky, A. N., Caceres-Chamizo, J. P. & Sanner, J. (2012) Scorpiodinipora costulata (Canu & Bassler, 1929) (Bryozoa, Cheilostomata), a taxonomic and biogeographic dilemma: complex of cryptic species or humanmediated cosmopolitan colonizer? Zoosystema, 34, 123 - 138. https: // doi. org / 10.5252 / z 2012 n 1 a 5","Taylor, P. D. & Tan, S. - H. A. (2015) Cheilostome Bryozoa from Penang and Langkawi, Malaysia. European Journal of Taxonomy, 149, 1 - 34. https: // doi. org / 10.5852 / ejt. 2015.149","Yang, J. Y., Seo, J. E. & Gordon, D. P. (2018) Sixteen new generic records of Korean Bryozoa from southern coastal waters and Jeju Island, East China Sea: evidence of tropical affinities. Zootaxa, 4422 (4), 493 - 518. https: // doi. org / 10.11646 / zootaxa. 4422.4.3"]}

Rhynchozoon setiavicularium n. sp. (Fig. 16) urn:lsid:zoobank.org:act: E9957EDC-7E61-4D15-ADD3-5FA8627BF14A Etymology. The specific name is a combination of the Latin seta (bristle) and avicularium, referring to the inferred setiform end of the frontal avicularia. Material examined. Holotype, VNMN-0263 (CT-40), on SEM stub. Measurements. AzL, 0.40–0.54 (0.458 ± 0.044); AzW, 0.30–0.35 (0.323 ± 0.018); (n = 10, 1). OrL, 0.11–0.12 (0.116 ± 0.005); OrW, 0.11–0.13 (0.113 ± 0.006) (n = 9, 1). OvL, 0.16–0.21 (0.175 ±0.018); OvW, 0.18–0.21 (0.197 ± 0.012) (n = 7, 1). Frontal AvRL, 0.19–0.24 (0.221 ± 0.018); Frontal AvRW, 0.067 –0.089 (0.075 ± 0.007) (n = 10, 1). Diagnosis. Suboral sinus U-shaped, moderately shallow, narrow. 20–23 oral denticles. Oral spines lacking. Zooids with suboral avicularium and single frontal avicularium. Suboral avicularium with mandibular part of rostrum right-angled, and with proximal uncinus. Rostrum of frontal avicularia diamond shaped, decurved, with narrow, distal channel for setiform mandible; avicularian crossbar simple. Ooecium with large endooecial panel vertical in peristome, flat, with marginal pustulation; labellum wide. Scattered surface nodules in older parts of colony. Description. Colony encrusting, sheet-like, unilaminar, possibly becoming bi- or trilaminar with age through frontal budding, but not nodular. Zooids irregularly hexagonal or barrel-shaped; discrete only near margin, delineated by line of calcification between adjacent rows of marginal areolae. Frontal wall initially convex, smooth, imperforate, with six or seven small, irregular areolae along each lateral margin. Orifice with anter broader than long; overall (including sinus) about as long as broad. Median sinus distinct, moderately wide and deep, U- or rounded-V-shaped, flanked by prominent, rounded condyles, bounded by small secondary condyles. Periphery of orifice distal to condyles beaded with 20–23 rounded denticles. Oral spines lacking. With age and increasing secondary calcification, zooidal boundaries obscured; frontal surface smooth, but irregular, with scattered coarse tubercles; secondary orifice with distinct, wide pseudosinus on one side or other, with up to five or six tuberculate prominences around proximal and lateral margins. Most zooids have suboral avicularium, offset toward one side or other of midline; rostrum length equal to or somewhat greater than orifice width; rostral plane tilted toward distal end of zooid, almost perpendicular to frontal plane; rostrum with complete crossbar; anter semicircular, with smooth cryptocyst, and bearing slight uncinus; mandibular part asymmetrical but not curved, forming right triangle with narrow base along crossbar, side toward orifice at right angle to crossbar, other side longer; cryptocystal margin of rostral part irregular with coarse, rounded denticles. Most zooids having single frontal avicularium roughly in center of frontal shield, directed laterally or proximally. Rostrum up to twice as long as orifice width; ratio of average rostrum length to rostrum width = 2.9. Rostral poster triangular, with smooth crytocyst. Mandibular part long-triangular, tapering and quite narrow distally, forming groove for setiform mandible; often decurved; opesial opening long-triangular, opesial margin irregular, with several coarse, rounded denticles on each side. Ooecia seen forming rapidly near colony margin, appearing in second row of fully formed zooids in from margin; completely immersed with age, visible only inside sunken peristome; window of non-calcified ectooecium exposing large, semicircular zone of endooecium on proximal face of ooecium; endooecial zone vertically oriented in peristome, smooth, flat, but with small pustules around margin; with unusually broad labellum along proximal margin of ooecium, beneath exposed endooecial area. Remarks. This species resembles Rhynchozoon scimitar Dick & Grischenko, 2017 in having a deep, narrow oral sinus; in having a single elongate, diamond-shaped frontal avicularium per zooid; in lacking oral spines; and in having the ooecium with a large endooecial panel of similar texture. However, in R. setiavicularium n. sp., the oral sinus is shallower, broader, and varies from rounded-V-shaped to U-shaped; the suboral avicularium is shorter, and the mandibular portion, while asymmetrical, is not curved but forms a right triangle. In R. setiavicularium n. sp., both a suboral and a frontal avicularium can occur on the same zooid, whereas in R. scimitar, zooids have one or the other. The frontal avicularium, while similarly elongate and diamond-shaped in the two species, is narrower distally and forms a distinct channel for a setiform end of the mandible in R. setiavicularium n. sp.; furthermore, the frontal avicularian rostrum is often decurved in R. setiavicularium n. sp.; in R. scimitar, occasional frontal rostra are curved in the frontal direction, but never decurved. While the ooecia are similar in the two species, they are smaller in R. setiavicularium n. sp.; the endooecial panel seems proportionally larger; and the labellum is much wider. Rhynchozoon haha Hayward, 1988 and R. splendens Hayward, 1988 have a similarly diamond-shaped frontal avicularium. The former differs from R. setiavicularium n. sp. in having a broad, shallow proximal orifical sinus; the latter differs in having smaller, less-elongate frontal avicularia, the ooecium with a much smaller ectooecial panel and narrow labellum, and the suboral avicularian rostrum with a distinct uncinus, or projection, on the proximal end. Distribution. Co To Island is the only known locality.

Antropora minor (Hincks, 1880) (Figs 4 C���F; 20B) ���? Membranipora trifolium, S. Wood, var. minor ��� Hincks, 1880, p. 87, pl. 11, fig. 6. Antropora minor: Tilbrook 1998, p. 34, fig. 2A���F, and synonyms therein; Tilbrook et al. 2001, p. 41, fig. 3A; Tilbrook 2006, p. 30, pl. 4B; Dick et al. 2006, p. 2209, fig. 5A, B; Gordon et al. 2007, p. 48, fig. 1G; Taylor & Tan, 2015, p. 13, fig. 7A. Material examined. VNMN-0217 (CT-11), VNMN-0218 (CT-20), VNMN-0219 (CT-37), VNMN-0220 (CT-47), VNMN-0221 (CT-48), VNMN-0276, (CT-52), on SEM stubs; VNMN-0222, 11 colony fragments. Measurements. AzL, 0.28���0.40 (0.350 �� 0.034); AzW, 0.20���0.26 (0.230 �� 0.015); OpL, 0.15���0.22 (0.185 �� 0.018); OpW, 0.12���0.15 (0.133 �� 0.012) (n = 15, 1). Description. Colony encrusting, sheet-like; initially unilaminar but becoming bi- or trilaminar as additional layers are produced, initiated by budding in frontal direction. Zooids small, distinct, delineated by sharp groove, distal third raised, forming sharp mural rim; gymnocyst negligible, sometimes evident at proximal end of zooid; cryptocyst extensive, coarsely granulate, widest proximally, narrowing laterally, continuing around inside of raised distal rim. Opesia occupying half or more of frontal length; irregular, pear-shaped, or oval; small, smooth gymnocystal papillae occasionally present proximally or proximolaterally. Spines lacking. Small interzooidal avicularia common in angular positions formed by zooidal intersections; on raised cystid, mandible rounded, no crossbar. Vicarious avicularia rare; only one found among all specimens examined; similar in size (0.35 �� 0.21 mm) to autozooids, with raised, smooth-walled, circular mandibular part of rostrum separated from smaller, proximal, cryptocystal part by sharp, medially directed condyles. Reproducing zooids with vestigial ooecium manifested as crescent-shaped zone of smooth, inflated calcification at proximal end of next-distal zooid; when ooecium fully developed, cap entirely covering sharp distal rim of reproducing zooid. Embryos brooded endozooidally. Ancestrula similar to but smaller than subsequent zooids; appears to bud first daughter zooid(s) distolaterally on one or both sides, with subsequent spiral budding pattern from first daughter zooid on one side. Remarks. Diagnostic characters for this species include the irregular occurrence of ���kenozooidal papillae��� at the proximal end of some zooids, and large vicarious avicularia interspersed with autozooids (Tilbrook 1998). Some zooids in our specimens have proximal papillae, but these do not appear to be kenozooidal, but rather are raised swellings in the exposed proximal gymnocyst. Some of the supposed kenozooidal papillae illustrated by Tilbrook (1998) likewise appear to be gymnocystal swellings rather than interzooids (e.g. Tilbrook 1998, fig. 2C), whereas others are ambiguous (e.g. Tilbrook 1998, fig. 2E). We observed only one vicarious avicularium, with most colonies lacking any; Tilbrook (1998) noted that vicarious avicularia may be absent from large areas of some colonies of A. minor. Distribution. Originally described from Bahia, Brazil (Hincks 1880 b), this nominal species putatively has a circumtropical distribution in shallow shelf areas (Tilbrook 1998, 2006; Tilbrook et al. 2001). Given the improbability of connectivity between Atlantic and Pacific populations in the era preceding widespread transoceanic shipping, this species has either been widely dispersed anthropogenically over the past few centuries, or comprises a complex of morphologically similar but genetically divergent geographical clades. The closest previous records to northern Vietnam are from the Philippines, Sabah (Malaysia), and China (Tilbrook 1998, 2006)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 210-211, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Hincks, T. (1880) Contributions towards a general history of the marine Polyzoa. II. Foreign Membraniporina. Annals and Magazine of Natural History, Series 5, 6, 81 - 92, pls. 9 - 11. https: // doi. org / 10.1080 / 00222938009458895","Tilbrook, K. J. (1998) The species of Antropora Norman, 1903 (Bryozoa: Cheilostomatida), with the description of a new genus in the Calloporoidea. Records of the South Australian Museum, 31, 25 - 49.","Tilbrook, K. J., Hayward, P. J. & Gordon, D. P. (2001) Cheilostomatous Bryozoa from Vanuatu. Zoological Journal of the Linnean Society, 131, 35 - 109. https: // doi. org / 10.1111 / j. 1096 - 3642.2001. tb 01309. x","Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp.","Dick, M. H., Tilbrook, K. J. & Mawatari, S. F. (2006) Diversity and taxonomy of rocky-intertidal Bryozoa on the Island of Hawaii, USA. Journal of Natural History, 40, 2197 - 2257. https: // doi. org / 10.1080 / 00222930601062771","Gordon, D. P., Hossain, Md. M. M. & Wood, T. S. (2007) The known and anticipated bryozoan diversity of Bangladesh. Journal of Taxonomy and Biodiversity Research, 1, 45 - 58.","Taylor, P. D. & Tan, S. - H. A. (2015) Cheilostome Bryozoa from Penang and Langkawi, Malaysia. European Journal of Taxonomy, 149, 1 - 34. https: // doi. org / 10.5852 / ejt. 2015.149","Hincks, T. (1881) Contributions towards a general history of the marine Polyzoa. IV. Foreign Membraniporina (second series). Annals and Magazine of Natural History, Series 5, 7, 147 - 156, pls. 8 - 10. https: // doi. org / 10.1080 / 00222938109459489"]}

Disporella phaohoa n. sp. (Figs 18, 20F) urn:lsid:zoobank.org:act: 6C16A5DC-2688-4DBD-AF0D-25CC88754823 Etymology. The specific name comes from the Vietnamese ph��o hoa (firework), referring to the starburst pattern of the radiating connate series of zooids. Material examined. VNMN-0268 (CT-35), three colonies on SEM stub; largest colony, with broken brood chamber, is the holotype; the others are paratypes. Paratypes, VNMN-0268 (two of three colonies), VNMN-0269 (CT-36), on SEM stubs. Other material: VNMN-0256, one colony with Plesiocleidochasma porcellaniforme; VNMN-0270, seven dried specimens. Measurements.Az inside diameter, 0.055 ���0.080 (0.068 ��0.007); alveoli inside diameter, 0.069 ���0.115 (0.085 �� 0.012) (n = 15, 1). Diameter of largest colony observed 5.5 mm; most colonies 4.0��� 4.5 mm. Diagnosis. Mature colony typically ca. 5 mm in diameter. Colony with smooth (non-spinous) marginal lamina; with single macula. Zooids in radiating connate series, two to three zooids wide in widest portion. Peristomes erect at margin, each with acute tip distal to orifice. Alveolus inside diameter up to twice peristome inside diameter; alveolar spinules lacking. Brood chamber smooth-walled, in macular center; ooeciostome angled to frontal surface, not flared. Description. Colony disk-like, circular or elliptical in outline; surrounded by narrow marginal lamina traversed by radiating lines indicating newly forming zooidal boundaries; comprising single circular or irregularly elongate macula. Zooids arranged in connate series radiating from center; series initially one zooid wide toward center but two (occasionally three) zooids wide in alternating arrangement toward margin. As colony size increases, space between adjacent radiating connate series widening, with new, secondary connate series not reaching center of macula becoming intercalated between them. Peristomes in radiating series shorter toward center, becoming increasingly longer and sometimes erect toward margin; end of peristome with acute tip distal to orifice. Alveoli (= kenozooids) irregularly polygonal; inside diameter up to twice that of autozooids; becoming constricted by centripetally deposited calcification; no spinules observed inside alveoli. Brood chamber evident as smooth area in macular center, sometimes extending as interradial lobes; with distinct, smooth roof; presumed ooeciopore appears to open at end of tube angled to frontal surface; opening terminally or frontally directed, not flared. Remarks. Disporella is a speciose genus, with close to 60 nominal species described worldwide (Bock 2018). The name Lichenopora Defrance, 1823 was mistakenly applied to this genus for over a century, until Gordon & Taylor (1997, 2001) clarified that it applies to Cretaceous to Miocene species having conical-pedunculate colonies, with the names Disporella Gray, 1848 and Patinella Gray, 1848 applying to Cenozoic and Recent species having adnate, discoid colonies. Among several nominal Disporella species previously reported in East Asia (as Lichenopora), the species most similar to D. phaohoa n. sp. is D. wanganuiensis (Waters, 1887), as redescribed by Gordon & Taylor (2001). The two species have in common a smooth marginal lamina; large alveoli lacking pinhead spinules; zooids arranged in connate series one to three zooids wide; and the brood chamber located in the macular center, with or without interradial lobes. Disporella wanganuiensis differs in having alveolar walls extending over the surface the brood chamber roof, which also bears numerous, minute pseudopores that are nearly closed by fine radial spokes (Gordon & Taylor 2001: fig. 34); in D. phaohoa n. sp., the roof of the brood chamber is smooth, without the alveolar covering or pseudopores. In D. wanganuiensis, the ooeciostome is flared and distinctively composed of stacked, concentric layers. While it is not clear whether the arrowed structure in Fig. 18F represents the ooeciostome in D. phaohoa n. sp., as opposed to the terminal end of an isolated autozooid, a structure like this was seen in the macular center in several colonies. Finally, Disporella wanganuiensis can produce daughter colonies by frontal budding, leading to stacked colonies, a feature not observed in D. phaohoa n. sp. Disporella wanganuiensis was originally described from New Zealand, where it is a shelf species typically found on calcareous substrata, with a known depth range of 107���419 m (Gordon & Taylor 2001). It is unlikely from an ecological standpoint that the same species also occurs in the shallow, subtropical, reef-rubble habitat at Co To. It is noteworthy that many of the synonyms Gordon & Taylor (2001) present for D. wanganuiensis are uncertain and prefaced by a question mark; records of that species from outside the New Zealand region need to be reexamined. Distribution. Co To Island is the only known locality., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 239-241, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Bock, P. (2018) Indexes to bryozoan taxa. Available from: http: // www. bryozoa. net / indexes. html (accessed 15 December 2018)","Defrance, J. L. M. (1823) Polypiers. In: Dictionnaire des Sciences Naturales. Vol. 26. F. G. Levrault, Strasbourg, pp. 1 - 553.","Gordon, D. P. & Taylor, P. D. (1997) The Cretaceous-Miocene genus Lichenopora (Bryozoa), with a description of a new species from New Zealand. Bulletin of the Natural History Museum, London, Geology, 53, 71 - 78.","Gray, J. E. (1848) List of the Specimens of British Animals in the Collections of the British Museum. Part 1. Centrionae or Radiated Animals. Trustees of the British Museum, London, pp. 91 - 151. [Polyzoa]","Waters, A. W. (1887) On Tertiary cyclostomatous Bryozoa from New Zealand. Quarterly Journal of the Geological Society, London, 43, 337 - 350, pl. 18. https: // doi. org / 10.1144 / GSL. JGS. 1887.043.01 - 04.27","Gordon, D. P. & Taylor, P. D. (2001) New Zealand Recent Densiporidae and Lichenoporidae (Bryozoa: Cyclostomata). Species Diversity, 6, 243 - 290. https: // doi. org / 10.12782 / specdiv. 6.243"]}

Plesiocleidochasma porcellaniforme (Soule, Soule & Chaney, 1991b) (Figs 14, 20G) Schedocleidochasma porcellaniforme Soule, Soule & Chaney, 1991b, p. 481, pl. 1, fig. 1, pl. 5, figs 3, 4, and synonyms therein. Schedocleidochasma porcellaniforme: Tilbrook et al. 2001, p. 98, fig. 21A, B; Liu et al. 2001, 705, pl. 79, figs 1���3; Tilbrook 2006, p. 293, pl. 64B. Cleidochasma porcellanum (Busk): Winston and Heimberg 1986, p. 34, figs 85���87. Material examined. VNMN-0256 (CT-7), VNMN-0257 (CT-8), VNMN-0258 (CT-13), VNMN-0259 (CT-15), VNMN-0260 (CT-29), VNMN-0261 (CT-31), on SEM stubs. Measurements. AzL, 0.37���0.47 (0.403 �� 0.025); AzW, 0.22���0.39 (0.306 �� 0.041) (n = 15, 1). OrL, 0.11���0.15 (0.131 �� 0.010); OrW, 0.089 ���0.115 (0.099 �� 0.007) (n = 15, 2). OvL, 0.17���0.22 (0.194 �� 0.015); OvW, 0.19���0.25 (0.221 �� 0.015) (n = 15, 1). Description. Colony unilaminar, encrusting, sheet-like; sometimes partly bilaminar due to self-overgrowth. Zooids small, boundaries indistinct. Frontal wall slightly convex, imperforate; surface weakly pustulose; often bearing several scattered, low, rounded nodules; with a few marginal pores, some of which may be positioned inside margin. Marginal zooids show three small spine bases, which are not evident in interior zooids. Orifice keyhole-shaped; anter circular or subcircular, separated by strong, proximomedially directed condyles from narrower, rounded poster. Frontal avicularia single or paired lateral or proximolateral to poster, although zooids lacking frontal avicularia not uncommon. When paired, avicularia directed at slightly different angles, one sometimes pointing laterally and other distolaterally. Avicularian rostrum rounded proximally, acute distally; crossbar complete or incomplete; opesial opening more or less arrowhead-shaped. Ooecium subimmersed, imperforate, same texture as frontal wall; opening covered by broad, flat labellum, with narrow transverse slit above, distinct lateral slits, and narrow transverse slit below that merges with lateral slits. Remarks. This species was originally placed in the genus Schedocleidochasma Soule, Soule & Chaney, 1991b, but Berning (2012), concluding that no clear boundary could be drawn between that genus and Plesiocleidochasma, declared the former a junior synonym of the latter. Distribution. Widely distributed in the central to western Pacific, ranging from the Hawaiian Islands westward to Indonesia, Thailand, Vietnam, and the Maldives (Indian Ocean) (Soule et al. 1991b; Tilbrook 2006; this study)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on page 232, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Soule, D. F., Soule, J. D. & Chaney, H. W. (1991 b) New tropical Pacific and Indian Ocean Cleidochasmatidae (Cheilostomata: Ascophora). In: Bigey, F. P. & d'Hondt, J. - L. (Eds.), Bryozoaires Actuels et Fossiles: Bryozoa Living and Fossil. Societe des Sciences Naturelles de l'Ouest de la France, Nantes, pp. 465 - 486.","Tilbrook, K. J., Hayward, P. J. & Gordon, D. P. (2001) Cheilostomatous Bryozoa from Vanuatu. Zoological Journal of the Linnean Society, 131, 35 - 109. https: // doi. org / 10.1111 / j. 1096 - 3642.2001. tb 01309. x","Liu, X., Yin, X. & Ma, J. (2001) Biology of Marine-Fouling Bryozoans in the Coastal Waters of China. Science Press, Beijing, 860 pp., 82 pls.","Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp.","Winston, J. E. & Heimberg, B. F. (1986) Bryozoans from Bali, Lombok, and Komodo. American Museum Novitates, 2847, 1 - 49.","Berning, B. (2012) Taxonomic notes on some Cheilostomata (Bryozoa) from Madeira. Zootaxa, 3236, 36 - 54. https: // doi. org / 10.11646 / zootaxa. 3236.1.2"]}

Rhynchozoon latiavicularium n. sp. (Fig. 17) urn:lsid:zoobank.org:act: D543ACD0-6CEA-46F5-8624-F9FD808E0A37 Etymology. The specific name combines the Latin word lata (wide) with avicularium, referring to the relatively wide frontal avicularia. Material examined. Holotype, VNMN-0264 (CT-14); paratypes, VNMN-0265 (CT-4), VNMN-0266 (CT-25), VNMN-0267 (CT-34), all on SEM stubs. Measurements. AzL, 0.45–0.63 (0.536 ± 0.062); AzW, 0.30–0.54 (0.399 ± 0.056); OrL, 0.10–0.14 (0.121 ± 0.010); OrW, 0.10–0.12 (0.106 ± 0.006) (n = 15, 2). OvL, 0.14–0.21 (0.173 ± 0.023); OvW, 0.19–0.23 (0.208 ± 0.013) (n = 15, 1). Frontal AvRL, 0.14–0.18 (0.157 ± 0.014); frontal AvRW, 0.066 –0.102 (0.080 ± 0.008) (n = 30, 2). Diagnosis. Suboral sinus U-shaped, moderately shallow, narrow, flanked by straight orificial margin and broad, semicircular condyles. Oral denticles indistinct. Oral spines lacking. Zooids with suboral avicularium and single frontal avicularium. Suboral avicularium relatively broad; uncinus scarcely evident. Frontal avicularia relatively short, broad; weakly diamond shaped or semicircular proximally; scarcely decurved, with triangular mandibular portion lacking setiform end; paired crossbar elements V-shaped. Ooecium with transversely oval endooecial panel in peristome; labellum present but not markedly broad. Cylindrical projections around secondary orifice in older parts of colony. Description. Colony encrusting, sheet-like, initially unilaminar, developing bilaminar zones due to frontal budding, but not nodular. Zooids irregularly hexagonal but boundaries distinct only at colony margin. Frontal wall at margin smooth, convex, imperforate, with 7–10 small, circular areolae along each lateral margin; with thickening frontal calcification, areolar openings become larger and fewer, five or six along each lateral margin. Primary orifice with anter D-shaped or nearly circular; median sinus variable, ranging from narrowly U-shaped to more broadly rounded-V-shaped, flanked on each side by small shelf, with rounded condyle filling angle between shelf and lateral orifical margin; condyles not directed distally. Oral spines lacking. With increased calcification, scattered low, rounded tubercles appearing on frontal wall, though surface texture remaining smooth; from two to seven short, blunt cylindrical processes forming around secondary orifice as outgrowths from the frontal walls of surrounding zooids; and deep, asymmetrical secondary orifical sinus forming to one side of midline or other. Zooids with suboral avicularium, usually 20–25% longer than orifice width; poster broadly semicircular, with smooth cryptocyst. Rostrum directed laterally, with rostral plane also tilted slightly toward distal end of zooid; mandibular portion asymmetrical, forming right triangle, or symmetrical, forming short-equilateral triangle; opesial margin of mandibular portion irregular with one or two coarse, nodular denticles on each side. Hinge element on each side of rostrum narrowly V-shaped, apex pointing medially, with or without complete crossbar extending between opposing elements. Suboral avicularium occasionally larger, twice as long as orifice width, with rostral plane convex in frontal direction. Most zooids have single frontal avicularium located in proximal half of frontal shield, directed distolaterally, laterally, proximolaterally, or proximally; frontal avicularia similar in size and shape to suboral avicularia; ratio of average rostrum length to rostrum width = 1.9; proximal end of rostrum usually acute (rostrum diamond-shaped), but sometimes rounded as in suboral avicularia; mandibular portion usually symmetrical and long-triangular, sometimes asymmetrical and comprising right triangle. Opesial margin of mandibular portion irregular, with up to six coarse, rounded denticles on each side. Rostrum slightly decurved at end, indicating mandible is probably hooked distally. Ooecium immersed with age; non-calcified ectooecium leaving circular or oval zone of exposed endooecium vertically oriented in sunken peristome, with broad labellum along proximal ooecial margin; secondary calcification atop ooecium typically giving rise to one or two coarse tubercles. Remarks. Rhynchozoon latiavicularium n. sp. is quite similar to R. setiavicularium n. sp. above, but differs in the following characters (character state of R. setiavicularium n. sp. in parentheses). Rhynchozoon latiavicularium n. sp. has larger zooids, average ZL × ZW = 0.54 × 0.40 mm (0.46 × 0.32 mm); the orifical condyles are not discrete, filling angle between lateral and proximal margins of orifice (discrete, distally directed knobs); the frontal avicularian rostrum is wider relative to length, with an average L/W ratio ≈ 2.0, with a triangular mandible not distinctly nar- row distally (L/W ratio ≈ 3.0, tapering and narrow distally); the frontal avicularian rostrum is not markedly decurved (rostrum often markedly decurved); the poster in the frontal avicularia varies from acute and triangular to rounded and semicircular (sharply acute and triangular); the avicularian hinge element comprising each side of the crossbar is sharply V-shaped (hinge elements uniform in width, not V-shaped); the endooecial panel on the proximal side of the ooecium is smaller, and transversely oval or semicircular in outline (proportionally larger, semicircular). Rhynchozoon setiavicularium n. sp. and R. latiavicularium n. sp. are probably closely related, as the differences between them are slight. Dick & Mawatari (2005) documented a parallel case for two similar Rhynchozoon species co-occurring at a locality in southeastern Alaska. In that study, a mitochondrial DNA (mtDNA) analysis detected two mitochondrial clades, and a morphological analysis showed slight but consistent qualitative and quantitative, clade-specific differences. One species had already been described and the other was eventually described as new (Dick et al. 2005). Distribution. Co To Island is the only known locality.

Smittipora harmeriana (Canu & Bassler, 1929) (Fig. 5 A���C) Velumella harmeriana Canu & Bassler, 1929: p. 128. Smittipora harmeriana: Winston & Heimberg 1986, p. 11, figs 23���24; Hayward 1988, p. 281, Fig. 1c; Tilbrook 2006, p. 76, pl. 12B. Smittipora abyssicola: Harmer 1926, p. 259, pl. 16, figs 10���13; not Smittipora abyssicola (Smitt, 1873). Material examined. VNMN-0223 ( CT-2), on SEM stub; VNMN-0224, six fragments. Measurements. AzL, 0.51���0.79 (0.664 �� 0.075); AzW, 0.33���0.49 (0.429 �� 0.050); AzOpL, 0.15���0.21 (0.184 �� 0.015); AzOpW, 0.14���0.18 (0.163 �� 0.010); reproductive ZL, 0.60���0.81 (0.677 �� 0.059); reproductive ZW, 0.37���0.48 (0.426 �� 0.036); reproductive ZOpL, 0.20���0.29 (0.251 �� 0.026); reproductive ZOpW, 0.17���0.20 (0.185 �� 0.010); AvL, 0.44���0.59 (0.522 �� 0.043); AvW, 0.22���0.42 (0.305 �� 0.051); AvOpL, 0.17���0.27 (0.219 �� 0.024); AvOpW, 0.079 ���0.133 (0.111 �� 0.018) (n = 15, 1). Description. Colony unilaminar, encrusting, sheet-like. Zooids irregularly semi-hexagonal proximally, rounded distally; distinct, delineated by sharp incision. Cryptocyst extensive, completely granulated, raised around margins to form rounded mural rim, depressed around and proximal to opesia, but forming broad median lip slightly turned up along proximal opesial margin, flanked by opesiular indentations. Inside opesia distally, below level of frontal surface, is a nearly semicircular shelf with straight proximal margin. Spines lacking. Opesiae campanulate in outline, dimorphic. Smaller opesiae slightly longer than broad, semicircular distally, widest proximally, with slight or marked opesiular indentations in proximolateral corners. Larger opesiae longer relative to width; opesiular indentations similarly variable. Avicularia large, interzooidal, shorter and narrower than autozooids; truncate, rounded, or triangular distally, not curved; frontal surface like that of autozooids; opesia long-oval, often widest distally, with center of opesia at or distal to center of zooid; crossbar lacking; paired condylar socket on each side at top of mural rim flanking distal half of avicularian opesia. Reproducing zooids have vestigial ooecium in form of small, semicircular cap immediately distal to orifice, outlined by distal groove and flanking sutures, often not evident in putatively reproducing zooids with large opesia; conversely, sometimes evident in presumably non-reproducing zooids with smaller opesia. Remarks. Harmer (1926) considered this Indo-Pacific species to be conspecific with Smittipora abyssicola (Smitt, 1873), originally reported from the Caribbean region. Canu & Bassler (1929) realized it was not the same species as treated by Harmer and gave it a new name, Velumella (= Smittipora) harmeriana, with no additional description. Harmer���s (1926) description and illustrations, which thus comprise the original description, well represent the material found at Co To. Harmer specifically mentions opesial dimorphism between reproducing and non-reproducing zooids, and his illustrations show diagnostic features seen at Co To, including the opesial dimorphism; avicularia that are shorter and narrower than autozooids, and truncate distally; the distal shelf inside the opesia; and the suture lines flanking the inconspicuous, often completely immersed vestigial ooecium. An important character in onychocellids is the nature of the avicularian mandible, which often consists of a median rachis with expanded ���wings��� on one or both sides; unfortunately, the mandibles were missing in the Co To specimens. Tilbrook (2006) noted for material from the Solomon Islands that there is no opesial dimorphism, which is contrary to Harmer���s (1926) description and our observations of the Co To specimens. However, at Co To, while opesiae showed a bimodal size distribution, there was only a loose correlation between opesia size and presence of the reduced ooecium, with some zooids of each size having an ooecium. Distribution. This species has a broad Indo-West Pacific distribution, having been reported from Mauritius (Hayward 1988); Indonesia, Torres Strait, the Celebes, and Myanmar (Burma) (Winston & Heimberg 1986); Ceylon (Sri Lanka), Queensland, and Singapore (Harmer 1926); and the Solomon Islands (Tilbrook 2006). The Co To record extends the previously known range (close to and south of the equator) northward nearly to 21��N., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 211-212, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Canu, F. & Bassler, R. S. (1929) Bryozoa of the Philippine region. United States National Museum Bulletin, 100, I-XI + 1 - 685.","Winston, J. E. & Heimberg, B. F. (1986) Bryozoans from Bali, Lombok, and Komodo. American Museum Novitates, 2847, 1 - 49.","Hayward, P. J. (1988) Mauritian cheilostome Bryozoa. Journal of the Zoological Society of London, 215, 269 - 356. https: // doi. org / 10.1111 / j. 1469 - 7998.1988. tb 04900. x","Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp.","Harmer, S. F. (1926) The Polyzoa of the Siboga Expedition, part 2, Cheilostomata Anasca. Siboga Expedition Reports, 28 b, v-vii + 183 - 501, pls. 13 - 34.","Smitt, F. A. (1873) Floridan Bryozoa, collected by Count L. F. de Pourtales. Part 2. Kongliga Svenska Vetenskaps-Akademiens Handlingar, 11, 1 - 83, pls. 1 - 13."]}

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): 201-252, DOI: https://doi.org/10.11646/zootaxa.4747.2.1

Trypostega henrychaneyi Tilbrook, 2006 (Fig. 6 A���D) Trypostega henrychaneyi Tilbrook, 2006, p. 110, pl. 19D���F, and synonyms therein. Trypostega henrychaneyi: Gordon et al. 2007, p. 49, fig. 2E. Material examined. VNMN-0225 ( CT-43), on SEM stub. Measurements. AzL, 0.34���0.49 (0.402 �� 0.045); AzW, 0.19���0.29 (0.242 �� 0.033) (n = 10, 1). OrL, 0.061 ��� 0.101 (0.080 �� 0.011); OrW, 0.059 ���0.101 (0.075 �� 0.011); distal zooeciule L, 0.059 ���0.226 (0.085 �� 0.032); distal zooeciule W, 0.059 ���0.226 (0.093 �� 0.054) (n = 12, 1). OvL, 0.226; OvW, 0.213 (n = 1). Description. Colony unilaminar, encrusting, sheet-like. Autozooids spindle-shaped, delineated by shallow groove, boundaries often unclear due to low relief of zooids. Frontal wall only slightly convex, often with faint transverse striation, with approximately 50 to 80 circular, evenly spaced pseudopores. Orifice flush with frontal surface, pear-shaped, longer than wide, anter separated from poster by sharp, proximomedially directed condyles; poster tripartite, with lateral indentations just proximal to condyles. Zooeciule distal to each autozooid and possibly each ooecium; small, irregularly quadrate, often not much larger than area of orifice, with small, circular orificial opening and several pseudopores. Only one ooecium observed; longer than broad, perforated over entire surface by pseudopores of same size and spacing as on frontal wall. Remarks. This species is identified by the pear-shaped orifice with a relatively narrow, tri-partite poster, and relatively small zooeciules. Tilbrook���s (2006) original description indicates more numerous (80���100), somewhat smaller pseudopores in the frontal wall than in the Co To specimen (50���80), although variation is evident even between the two images of complete zooids he shows for this species. In addition, zooids in the Co To specimen have the orificial poster narrower than indicated in the original description, although some zooids at Co To have a wider poster. Finally, average zooid size in the Co To specimen is somewhat smaller than in the original description (0.40 �� 0.24 mm, compared to about 0.48 �� 0.28 mm). Distribution. Tropical Pacific, from Panama westward to the Great Barrier Reef, New Guinea, Torres Strait, Sulu Archipelago, and Red Sea (Tilbrook 2006); Bangladesh (Gordon et al. 2007); Vietnam., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on page 214, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp.","Gordon, D. P., Hossain, Md. M. M. & Wood, T. S. (2007) The known and anticipated bryozoan diversity of Bangladesh. Journal of Taxonomy and Biodiversity Research, 1, 45 - 58."]}

Metroperiella cotoensis n. sp. (Figs 9 D���F; 20H) urn:lsid:zoobank.org:act: DEB38710-D95B-472C-8E28-83627EA25362 Etymology. The specific name comes from Co To Island, the type locality. Material examined. Holotype, VNMN-0238 (CT-39), on SEM stub. Measurements. AzL, 0.64���0.85 (0.709 �� 0.054); AzW, 0.37���0.49 (0.416 �� 0.035) (n = 15, 1). OrL, 0.16���0.19 (0.167 �� 0.012); OrW, 0.14���0.17 (0.154 �� 0.012) (n = 7, 1). OvL, 0.228 ���0.268 (0.249 �� 0.020); OvW, 0.281 ���0.344 (0.308 �� 0.033) (n = 3, 1). AvRL, 0.11���0.16 (0.138 �� 0.017); AvRW, 0.06���0.09 (0.071 �� 0.011) (n = 15, 1). Diagnosis. Frontal shield rugose, with numerous small psuedopores. Primary orifice longer than broad; proximal sinus broad and deep between small condyles. Rounded orificial collar proximolaterally and laterally, with slight lateral lappets. Single small avicularium in midline proximal to orifice, slightly shorter than orifice width; di- rected proximally, mandible long-triangular. Ooecium ininially smooth, hyperstomial, with numerous pseudopores, becoming rugose, immersed with age, but retaining pseudopores. Description. Colony encrusting, unilaminar, sheet-like. Zooids irregularly hexagonal or long-oval, distinct, delineated by groove. Frontal shield convex, evenly perforated by small pseudopores, surface between pores irregular. Orifice terminal, ovoid in overall shape, with anter horseshoeshaped, poster deeply and broadly U-shaped, sometimes flattened at bottom, separated from anter by small, rounded condyles. Dimorphism of primary orifice unclear; that of ooecium-bearing zooids possibly slightly larger, broader than that of zooids lacking ooecia. Orifice with smooth, blunt rim proximally and laterally, often raised laterally to form low lappet on each side; rim confluent distally with sharp, raised distal margin of orifice. Oral spines lacking. Each zooid bearing avicularium proximal to orifice; very close to orificial rim, usually in midline and directed proximally, occasionally slightly offset from midline and directed proximally or proximolaterally. Rostrum raised from frontal surface, face slightly convex rather than parallel to frontal plane; proximal end of rostrum semicircular, mandibular part long-triangular, acute; rostral opesia oval, crossbar complete; average avicularium length about equal to orifice width. No spatulate avicularia observed, either in place of suboral avicularium or as enlarged frontal avicularia; no interzooidal avicularia. Ooecium prominent, closed by operculum, slightly broader than long, proximal margin confluent with lateral oral lappets; surface smooth, evenly perforated by pseudopores except in proximocentral area; pseudopores about same size as frontal pores. With age, ooecium becomes completely immersed in thick, pseudoporous frontal calcification from next-distal zooid. Remarks. Most species of Metroperiella have a suboral avicularium that lies in the midline or can be somewhat offset from it, and that bears an acute or rounded mandible; in some species, it can be replaced by a more-or-less spatulate, sometimes enlarged median avicularium. In addition, in some species, zooids can additionally or exclusively produce an enlarged, markedly spatulate frontal avicularium proximolateral or lateral to the orifice, directed proximally or distally. In species that have an acute, usually median suboral avicularium, spatulate avicularia can be uncommon. Only a single size of acute, more-or-less median suboral avicularium was seen in the Co To specimen, although in this single, small colony, enlarged spatulate avicularia might simply be absent. However, two additional features distinguish it from congeners. One is the unusually deep, broad poster. The other is the immersed ooecium; while the ooecium in young stages is typical of the genus, few other Metroperiella have been reported to have an immersed ooecium in later stages. Metroperiella ovoidea (Canu & Bassler, 1929), described from the Philippines, has the ooecium similarly immersed, covered with the same frontal calcification as the autozooids, but the poster is shallower and narrower in that species, and the zooids smaller (ZL, 0.44���0.54 mm) (Canu & Bassler 1929). The median suboral avicularia are much smaller and, while there is no mention in the original description of large, spatulate adventitious avicularia, large vicarious avicularia occur. Metroperiella montferrandii (Audouin, 1826) is a common species supposedly distributed almost circumtropically, with previous records from the region of Vietnam (Tilbrook 2006); the median suboral avicularia are quite similar to those in M. cotoensis n. sp., but some zooids in M. montferrandii have the smaller, median avicularium replaced by an enlarged, spatulate avicularium proximolateral to the orifice, the poster is much shallower, and there has been no report of immersed ooecia. Metroperiella agassizi Winston & Woollacott, 2009, reported from Barbados in the eastern Caribbean, has monomorphic suboral avicularia similar in size, shape, and position to those in M. cotoensis n. sp., and zooid size is similar, but the poster is shallower and the ooecia in mature colonies are not immersed. Metroperiella anatina (Canu & Bassler, 1927), described from Hawaii, and M. hastingsi (Soule, Soule & Chaney, 1995), described from the Galapagos, may be conspecific with one another. In both species, some zooids have a relatively broad, deep poster, and many zooids have an acute suboral avicularium like that in M. cotoensis n. sp.; however, some zooids have the acute suboral avicularium replaced by an enlarged, spatulate avicularium in the same position. Distribution. Co To Island is the only known locality., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 221-223, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Canu, F. & Bassler, R. S. (1929) Bryozoa of the Philippine region. United States National Museum Bulletin, 100, I-XI + 1 - 685.","Audouin, J. V. (1826) Explication sommaire des planches de polypes de l'Egypte et de la Syrie, publiees par Jules-Cesar Savigny [Planches 1 - 14 by J-C Savigny (1817)]. In: Audouin J. V. (Ed.), Description de l'Egypte, ou Receuil des Observations et des Recherches qui ont ete Faites en Egypte Pendant l'Expedition de l'Armee Francaise, Publie par les Orders de sa Majeste l'Empereur Napoleon le Grand. Histoire naturelle. Tome 1. 4 e Partie. Imprimerie Imperiale, Paris, pp. 225 - 244.","Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp.","Winston, J. E. & Woollacott, R. M. (2009) Scientific results of the Hassler expedition. Bryozoa. No. 1. Barbados. Bulletin of the Museum of Comparative Zoology, 159, 239 - 300. https: // doi. org / 10.3099 / 0027 - 4100 - 159.5.239","Canu, F. & Bassler, R. S. (1927) Bryozoaires des Isles Hawai. Bulletin de la Societe des Sciences de Seine-et-Oise, 7 (Supplement), 1 - 67.","Soule, D. F., Soule, J. D. & Chaney, H. W. (1995) Taxonomic atlas of the benthic fauna of the Santa Maria Basin and western Santa Barbara channel. Irene McCulloch Foundation Monograph Series, 2, 1 - 344."]}

��� Stomatopora ��� sp. (Fig. 19C, D) Material examined. VNMN-0272 (CT-9), on SEM stub. Measurements. AzL (excluding peristome), 0.33���0.67 (0.542 �� 0.110); AzW, 0.16���0.32 (0.215 �� 0.042) (n = 12). Or inside diameter, 0.057 ���0.096 (0.079 �� 0.013) (n = 6). Description. Colony encrusting; zooids in dichotomously branching uniserial series, each autozooid producing pair of distal buds giving rise to bifurcation; angle of branching variable, from acute to obtuse; in some cases, one of paired daughter zooids at branch point aborted. Some paired daughter zooids at branch points appressed to one another for one-third to one-half their length before diverging; others diverging immediately at branch point. Zooids uniform in width, or up to twice as wide distally; wall with weak transverse striation, evenly perforated by minute pseudopores. Unbroken peristomes in our specimen not tall, length at most three times peristome diameter; acute projection on distal side at top of some peristomes. Some orifices partially closed, with restricted, circular opening in center. Brood chamber and ancestrula not observed. Remarks. The nominal genus Stomatopora has a stratigraphic range from the Triassic to Recent, with one Ordovician species of dubious status (Bock 2018). Harmelin (1979) discussed taxonomic problems associated with the genus, noting that the type species, Alecto dichotoma Lamouroux, 1821, described from a Jurassic fossil, initially forms a uniserial and biserial adnate colony but later forms erect branches, with the brood chamber arising as a simple swelling of the peristome. The generic placement of cyclostome species having a stable uniserial colony is thus problematic and will eventually require the erection of new genera based on information on budding patterns and the mode of formation the gonozooid (Harmelin 1979). While our specimen resembles several Jurassic species having a type-II budding pattern (Illies 1973), we cannot rule out that it is the adnate portion of a colony that will later form erect reproductive branches. Here we list this specimen as ��� Stomatopora ��� in the sense of a form-genus, making it accessible to literature searches in future studies of uniserial cyclostomes., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 242-243, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Bock, P. (2018) Indexes to bryozoan taxa. Available from: http: // www. bryozoa. net / indexes. html (accessed 15 December 2018)","Harmelin, J. - G. (1979) On some stomatoporiform species (Bryozoa Cyclostomata) from the bathyl zone of the northeastern Atlantic Ocean. In: Larwood, G. P. & Abbott, M. B, (Eds.), Advances in Bryozoology. Academic Press, London, pp. 403 - 422.","Lamouroux, J. V. F. (1821) Exposition Methodique des Genres de l'Ordre des Polypiers, avec leur Description et Celles des Principales Especes, Figurees dans 84 Planches; les 63 Premieres Apartenant a 1 'Histoire Naturelle des Zoophytes d'Ellis et Solander. V. Agasse, Paris, 115 pp., 84 pls. https: // doi. org / 10.5962 / bhl. title. 11328","Illies, G. (1973) Different budding patterns in the genus Stomatopora (Bryozoa, Cyclostomata). In: Larwood, G. P. (Ed.), Living and Fossil Bryozoa. Academic Press, London, pp. 307 - 315."]}

Dibunostoma reversum (Harmer, 1926) (Fig. 3) Thalamoporella rozieri form falcifera: Thornely 1905, p. 112. Calpensia reversa Harmer, 1926, p. 309, pl. 20, figs 13���16. Dibunostoma reversum: Cheetham 1963, p. 53, text-fig. 27a; Gordon et al. 2007, p. 49, fig. 2B. Thalamotreptos reversus: Soule et al. 1991a, p. 460, pl. 4, fig 5. Dibunostoma reversa: Badve & Sonar 1997, p. 36, pl. 1, fig. 2, pl. 4, fig. 1. ? Thalamoporella transversa Guha & Krishna, 2004, p. 29, figs 26���27. Not Dibunostoma reversum: Yang et al. 2018, p. 495, fig. 1. Material examined. VNMN-0213 (CT-26), VNMN-0273 (CT-49), VNMN-0274 (CT-50), VNMN-0275 (CT-51), on SEM stubs; VNMN-0214, five fragments. Measurements. AzL, 0.55���0.79 (0.654 �� 0.073); AzW, 0.30���0.41 (0.356 �� 0.033); OrL, 0.082 ���0.107 (0.094 �� 0.007); OrW, 0.10���0.13 (0.114 �� 0.011) (n = 15, 1). AvL �� AvW, 0.192 �� 0.189, 0.225 �� 0.175 (average = 0.209 �� 0.182); AvRL �� AvRW, 0.211 �� 0.063, 0.197 �� 0.065 (average = 0.204 �� 0.064) (n = 2, 2). Description. Colony encrusting, sheet-like, mostly unilaminar but self-overgrowth occurring in some parts of colony. Zooids rectangular, ovoid, spindle-shaped or irregularly polygonal; distinct, delineated by thin incision in raised marginal gymnocysts. Cryptocyst perforated by small, infundibular pseudopores proximal to level of opesiules; surface between pseudopores faintly pustulose, irregular. Frontal wall scarcely depressed below level of marginal rim proximally, markedly depressed proximal to opesia-orifice in vicinity of opesiules; rising sharply, sometimes nearly vertically, from opesiules to orifice. Smooth gymnocystal calcification surrounding orifice laterally and distally; within gymnocystal region and lateral to orifice on each side is pronounced, smooth, conical lateral-oral tubercle. Opesia-orifice D-shaped, on average slightly broader than long; with low, narrow, smooth, rim raised around periphery laterally and distally; proximal margin straight, without rim. Narrow shelf around curvature of distal orificial wall, just inside orifice. Oral spines lacking. Opesiules irregularly circular or irregular, variable in size, their combined area sometimes less than area of orifice, sometimes nearly twice as great; set in from lateral margins. Avicularia interzooidal; uncommon, with only two found among hundreds of zooids in six colony fragments; ratio of average avicularium length (n = 2) to average autozooid length (n = 15), 0.32; chamber nearly square or long-rectangular, surrounded by same raised marginal rim as autozooids, imperforate; rostrum raised, smooth, with proximal end at center of chamber, mandibular end acutely long-triangular, of variable width, directed across proximolateral corner of chamber toward base of sister zooid, crossing and abutting distal orificial margin. Kenozooids common, ranging in size from much smaller than to as large as autozooids; surface typically smooth, set below raised marginal rim, with small, circular, central opening, sometimes additionally with a few tiny pseudopores. Autozooidal orifice can similarly have closure plate with circular central opening; orifices in this condition can give rise to two or three distal zooids, which in turn continue to bud distally, producing wedge-shaped zone of self-overgrowth (Fig. 3A, C), forming frontal layer. Ooecia not detected. Remarks. The generic history of this species is convoluted. Harmer (1926) originally described it in Calpensia Jullien, 1888, but had to amend the diagnosis of that genus to include opesiules descending to the basal wall, paired lateral-oral tubercles, and avicularia. Supporting placement in Calpensiidae, he found no trace of the internal spicules that are one of the defining features of Thalamoporellidae. Cheetham (1963) erected the new genus Dibunostoma in Calpensiidae (now synonymized with Microporidae) to accommodate Calpensia -like species having vicarious avicularia, lateral-oral tubercles, large opesiules, and a straight proximal margin of the orifice. Cheetham noted that Dibunostoma is intermediate between Calpensia and Thalamoporella, but differs from the latter in having a straight proximal orificial margin and in lacking polypide tubes. Soule et al. (1991a) reexamined Thornely���s (1905) specimen (Thalamoporella rozieri form falcifera), upon which Harmer (1926) had based his original description of Calpensia reversa, and detected compass spicules, which disqualified this species from Calpensia and Microporidae. Furthermore, they noted that several species of Thalamoporella have a straight proximal orificial margin. In addition, Harmer���s (1926) illustrations of C. reversa clearly show the basal insertions of calcified structures (presumably contributing to a polypide tube) descending from the opesial openings. It is thus now clear that Dibunostoma belongs in Thalamoporellidae rather than Calpensiidae (= Microporidae). Soule et al. (1991a) established the genus Thalamotreptos for thalamoporellids having one or both opesiules extending to the basal wall, the avicularian rostrum pointing proximally or proximolaterally and occupying most of the frontal surface of the chamber, and compasses as the only spicules present. However, it was not clear what distinguishes Thalamotrepos from Dibunostoma, and the former is now treated as a junior synonym of the latter. Dibunostoma, as it now stands, is characterized by a D-shaped orifice with a straight proximal margin; lateral-oral tubercles; basal insertions of one or both opesiules; the presence of only compass spicules; and vicarious (interzooidal) avicularia with the mandible pointing proximally or proximolaterally. Dibunostoma shares the first four of these features with some or many Thalamoporella species, which leaves only the nature of the avicularium defining the genus. Whether this is enough to ultimately justify a genus distinct from Thalamoporella is an open question (see Soule et al. 1992, p. 7). Interestingly, ooecia are unknown in Dibunostoma verrilli (Soule & Soule, 1970), D. expansa (Levinson, 1909), and D. reversum, the living species presently known (three other species are known only from the fossil record), and this might prove to be a diagnostic generic character. Guha & Krishna (2004) reported Thalamoporella transversa from the early Miocene (Aquitanian); that species is so similar to D. reversum that if it had been found in a Recent fauna, the two might well be considered conspecific. Zooid measurements are more similar between Miocene T. transversa (average ZL �� ZW, 0.635 �� 0.378 mm) and Recent D. reversum from Co To (0.654 �� 0.356 mm) than between either of these and Recent D. reversum from Bangladesh (ZL range, 0.45���0.62 mm; ZW range, 0.23���0.36; Gordon et al. 2007). The orifice in T. transversa is as broad as long, whereas it is broader than long in D. reversum at Co To. Gordon et al. (2007) did not adequately describe the orifice of D. reversum from Bangladesh, but it appears to be more like that in T. transversa than that in D. reversum from Co To. Thalamoporella transversa differs from Holocene���Recent D. reversum in having many (but not all) autozooids narrowing distally, appearing somewhat flask-shaped, and in having the mandible of the avicularium oriented perpendicular to the long axis of the next-proximal autozooid, rather than pointing proximolaterally. The large, autozooid-sized kenozooids with a small, circular opening, which were common in the Co To material and occurred in Holocene material from western India (Badve & Sonar 1997), were not reported in T. transversa (Guha & Krishna 2004), nor did Gordon et al. (2007) report them in Recent D. reversum from Bangladesh. While T. transversa and D. reversum may represent a single, non-branching phyletic lineage from Miocene to Recent, we suggest retaining different names for the Miocene and Holocene���Recent material, based on the slight differences between them and the epistemological difficulties inherent in demonstrating conspecificity between Miocene and Recent populations. However, T. transversa clearly belongs in Dibunostoma rather than Thalamoporella, and we propose a nomenclatural change to Dibunostoma transversum. Finally. we note that Badve & Sonar (1997), in their summary of the distribution of D. reversum but not in a corresponding table, mistakenly attributed a geological time range for D. reversum from Eocene to Recent, based on Cheetham (1963). However, Cheetham illustrated Recent D. reversum but Eocene D. purii Cheetham, 1963, when he erected Dibunostoma to accommodate those two temporally disjunct species. Yang et al. (2018) reported Dibunostoma reversum from Jeju Island, in the East China Sea off southern Korea. However, their material differs from other reports of both living and fossil D. reversum in several ways. All measurements in the Korean material are markedly larger (e.g. average AzL = 0.895 mm, AzW = 0.472 mm), and the peristomial region distal to the orifice is conspicuously expanded and flared. The interzooidal avicularia are different; the rostrum occupies the entire frontal surface of the chamber; the opesial opening is enlarged; and the mandible is short and wide, forming an equilateral triangle directed perpendicularly toward the orifice and indenting the contour of the orificial rim, rather than being markedly elongate and extending laterally along the distal margin of the rim. We thus conclude that the Korean material is not conspecific with D. reversum and requires description as a new species. Distribution. Dibunostoma reversum was originally described from Sri Lanka (Ceylon) (Harmer 1926), and Gordon et al. (2007) reported it from coastal Bangladesh. Co To is the third known locality for Recent material, extending the known range from the western Indian Ocean eastward to Vietnam. In the fossil record, it is known from Holocene deposits along the western coast of India (Badve & Sonar 1997)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 205-209, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Harmer, S. F. (1926) The Polyzoa of the Siboga Expedition, part 2, Cheilostomata Anasca. Siboga Expedition Reports, 28 b, v-vii + 183 - 501, pls. 13 - 34.","Thornely, L. R. (1905) Report on the Polyzoa collected by Professor Herdman, at Ceylon, in 1902. Report to the Government of Ceylon on the Pearl Oyster Fisheries of the Gulf of Manar, 4, 107 - 130.","Cheetham, A. H. (1963) Late Eocene zoogeography of the eastern Gulf Coast region. Memoirs of the Geological Society of America, 91, 1 - 113. https: // doi. org / 10.1130 / MEM 91 - p 1","Gordon, D. P., Hossain, Md. M. M. & Wood, T. S. (2007) The known and anticipated bryozoan diversity of Bangladesh. Journal of Taxonomy and Biodiversity Research, 1, 45 - 58.","Soule, D. F., Soule, J. D. & Chaney, H. W. (1991 a) Some little-known genera of Thalamoporellidae: Thairopora, Diploporella, and new genera Marsupioporella and Thalamotreptos. In: Bigey, F. P. & d'Hondt, J. - L. (Eds.), Bryozoaires Actuels et Fossiles: Bryozoa Living and Fossil. Societe des Sciences Naturelles de l'Ouest de la France, Nantes, pp. 447 - 464.","Badve, R. M. & Sonar, M. A. (1997) Some fossil neocheilostomine bryozoans from the Holocene of the west coast of Maharashtra and Goa, India. Journal of the Palaeontological Society of India, 42, 35 - 48.","Guha, A. K. & Krishna, K. G. (2004) Fossil Thalamoporella (Bryozoa) from the Tertiary Sequences of Western Kachchh, Gujarat, India. Irene McCulloch Foundation Monograph Series, 7, 1 - 51.","Yang, J. Y., Seo, J. E. & Gordon, D. P. (2018) Sixteen new generic records of Korean Bryozoa from southern coastal waters and Jeju Island, East China Sea: evidence of tropical affinities. Zootaxa, 4422 (4), 493 - 518. https: // doi. org / 10.11646 / zootaxa. 4422.4.3","Jullien, J. (1888) Bryozoaires. Mission Scientifique du Cap Horn 1882 - 1883, Series 6, 3, 1 - 92, 15 pls.","Soule, D. F., Soule, J. D. & Chaney, H. W. (1992) The genus Thalamoporella worldwide (Bryozoa Anasca): morphology, evolution and speciation. Irene McCulloch Foundation Monograph Series, 1, 1 - 93.","Soule, D. F. & Soule, J. D. (1970) New species of Thalamoporella (Ectoprocta) from Hawaii, examined by scanning electron microscopy. American Museum Novitates, 2417, 1 - 18."]}

Cranosina coronata (Hincks, 1881) (Fig. 4A, B) Membranipora coronata Hincks, 1881, p. 147, pl. 10, fig. 1. Setosellina coronata: Harmer 1926, p. 265, pl. 16, figs 2 ��� 4. Cranosina coronata: Tilbrook 2006, p. 25, pl. 2e; Taylor & Tan 2015, p. 12, fig. 6; Dick & Grischenko 2017, p. 63, fig. 6e, f. For other synonyms and records, see Harmer (1926) and Tilbrook (2006). Material examined. VNMN-0215 (CT-5), on SEM stub; VNMN-0216, four colony fragments. Measurements. AzL, 0.49���0.65 (0.573 �� 0.048); AzW, 0.32���0.50 (0.409 �� 0.047); OpL, 0.19���0.48 (0.391 �� 0.071); OpW, 0.15���0.27 (0.212 �� 0.033); AvRL, 0.08���0.22 (0.178 �� 0.036); AvRW, 0.09���0.18 (0.122 �� 0.028) (n = 15, 1). Description. Colony unilaminar, encrusting, sheet-like. Zooids distinct, delineated by deep groove; often widest at, or proximal to, middle. Cryptocyst extensive, comprising wide, rounded mural rim, granulated on sides and top, with coarse ridges perpendicular to opesia on inside of mural rim; mural rim smooth laterally and distally in opercular region. Opesia extensive, often irregular in outline. Avicularium distal to each zooid, distal end of rostrum forming semi-cylindrical channel to house setose mandible, directed laterally or slightly distolaterally. Spines lacking. Ooecia lacking; zooids use internal sac for brooding. Distribution. This species is broadly distributed in the Indo-West Pacific region, occurring from East Africa and the Red Sea to Indonesia, the Great Barrier Reef, New Guinea, Singapore, Malaysia, Vanuatu, the Solomon Islands, Vietnam, the Philippines, and Japan (Chimonides & Cook 1994; Tilbrook et al. 2001; Tilbrook 2006; Taylor & Tan 2015; Dick & Grischenko 2017; this study)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on page 209, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Hincks, T. (1881) Contributions towards a general history of the marine Polyzoa. IV. Foreign Membraniporina (second series). Annals and Magazine of Natural History, Series 5, 7, 147 - 156, pls. 8 - 10. https: // doi. org / 10.1080 / 00222938109459489","Harmer, S. F. (1926) The Polyzoa of the Siboga Expedition, part 2, Cheilostomata Anasca. Siboga Expedition Reports, 28 b, v-vii + 183 - 501, pls. 13 - 34.","Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp.","Taylor, P. D. & Tan, S. - H. A. (2015) Cheilostome Bryozoa from Penang and Langkawi, Malaysia. European Journal of Taxonomy, 149, 1 - 34. https: // doi. org / 10.5852 / ejt. 2015.149","Dick, M. H. & Grischenko, A. V. (2017) Rocky-intertidal cheilostome bryozoans from the vicinity of the Sesoko Biological Station, west-central Okinawa, Japan. Journal of Natural History, 51, 141 - 266. https: // doi. org / 10.1080 / 00222933.2016.1253797","Chimonides, P. J. & Cook, P. L. (1994) Notes on the genus Cranosina (Bryozoa, Cheilostomida). Zoologica Scripta, 23, 43 - 49. https: // doi. org / 10.1111 / j. 1463 - 6409.1994. tb 00372. x","Tilbrook, K. J., Hayward, P. J. & Gordon, D. P. (2001) Cheilostomatous Bryozoa from Vanuatu. Zoological Journal of the Linnean Society, 131, 35 - 109. https: // doi. org / 10.1111 / j. 1096 - 3642.2001. tb 01309. x"]}

Parasmittina acondylata n. sp. (Fig. 9 A���C) urn:lsid:zoobank.org:act: D3FE34D9-98B3-4883-9A6C-AC0C5B74281A Etymology. The specific name is derived from the Greek prefix a- (without) and condyle, referring to the apparent lack of condyles. Material examined. Holotype, VNMN-0236 (CT-32), on SEM stub. VNMN-0237, additional dried specimens. Measurements. AzL, 0.35���0.56 (0.430 �� 0.063); AzW, 0.19���0.32 (0.267 �� 0.037); SecOrL, 0.088 ���0.143 (0.119 �� 0.013); SecOrW, 0.077 ���0.117 (0.103 �� 0.009); OvL, 0.13���0.17 (0.158 ��0.014); OvW, 0.19���0.23 (0.203 �� 0.014) (n = 15, 1). AvRL, 0.07���0.13 (0.103 �� 0.024); AvRW, 0.03���0.04 (0.034 �� 0.003) (n = 12, 1). Diagnosis. Three oral spines. Orifice with lyrula moderately broad and tall, alate or non-alate; condyles lacking. Frontal shield coarsely pustulose; areolae conspicuous, circular. Single, rather small frontal avicularium per zooid, proximolateral to orifice (occasionally medial), abutting peristomial collar, directed proximally, rostrum elongate, narrow, rounded at both ends; no giant avicularia observed. Ooecium broader than long, smooth, with around 20 scattered pseudopores; peristomial rim continuous around proximal ooecial margin. Description. Colony encrusting, unilaminar, sheet-like. Zooids irregular; rectangular, barrel-shaped, or spindle-shaped; distinct, delineated by groove and marginal line flanked by opposing columns of areolae. Frontal wall highly convex, rising to raised peristomial collar surrounding orifice laterally and proximally; coarsely pustulose, with six to nine conspicuous areolae along each lateral margin, with short struts between adjacent areolae. Primary orifice submerged, appearing longer than broad, with median lyrula about one-third as wide as orifice; lyrula moderately long, tapering, weakly alate or truncate. Condyles appear lacking, or scarcely evident, possibly represented by slight, broad convexity on either side distolateral to lyrula. Secondary orifice pear-shaped in outline, with proximal median constriction forming weak or pronounced pseudosinus. Three oral spines. Many but not all zooids with single frontal avicularium abutting peristomial collar, offset to one side of midline or other, occasionally in midline; rostrum elongate, parallel-sided, rounded at both ends, directed proximally; opesial opening oval, occupying nearly half of rostrum; no crossbars observed, but possibly lost. Ooecium prominent, first forming as concavity in proximal frontal wall of next-distal zooid, later appearing to rest on frontal wall; broader than long; globose, somewhat flattened, smooth, with up to 25 small, scattered pseudopores. Sides of peristomial collar continue as raised lip around proximofrontal part of ooecium, forming secondary orifice; oocium ringed around lateral and distal margin with band of raised secondary calcification from next-distal zooid. Remarks. This species was detected as a single small, worn colony. While it clearly belongs in Parasmittina, it is unusual in lacking well-defined condyles, which is one of the diagnostic features of the genus. If condyles are present at all, they are evident only as a slight convexity in each lateral margin of the primary orifice, and we are aware of no other Parasmittina species with this condition. The frontal avicularia are similar in shape, size, and position to those in P. soulesi Scholz & Cusi, 1991, which differs in having two oral spines; the orifice with a narrow, truncate lyrula and massive condyles, creating a deep sinus on each side of the lyrula; and the ooecia subimmersed, with a single row of large pseudopores around the distal margin. Distribution. Co To Island is the only known locality., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 220-221, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Scholz J, & Cusi, M. A. V. (1991) Paleoecologic implications of modern coral and bryozoan communities from southern Leyte, Philippines. Mitteilungen aus dem Geologisch-Palaontologischen Institut der Universitat Hamburg, 71, 405 - 431."]}

Hippopodina adunca Tilbrook, 2006 (Fig. 10A) Hippopodina adunca Tilbrook, 2006, p. 248, pl. 54C, D, and synonyms therein. Hippopodina adunca: Dick & Grischenko 2017, p. 211, fig. 24a, b. Material examined. VNMN-0239 (CT-17), on SEM stub; VNMN-0240, two colony fragments. Measurements. AzL, 0.73���1.00 (0.850 �� 0.080); AzW, 0.56���0.84 (0.670 �� 0.079); OrL, 0.24���0.26 (0.248 �� 0.008); OrW, 0.19���0.24 (0.213 �� 0.015) (n = 15, 1). OrL, ooeciate zooid, 0.224; OrW, ooeciate zooid, 0.263 (n = 1). OvL, 0.602; OvW, 0.619 (n = 1). Description. Colony encrusting, sheet-like, unilaminar but occasionally bilaminar due to self-overgrowth. Zooids large, rectangular, delineated by groove. Frontal wall convex, perforated by numerous tiny pseudopores. Orifice hoof-shaped; poster same width as anter or slightly narrower, separated by sharp condyles; proximal margin of orifice straight or markedly concave. Orifices dimorphic, with those of ooecium-bearing zooids wider than those of zooids lacking ooecia. Adventitious avicularia usually paired, sometimes single; each with large chamber lateral to orifice, rostrum long, tapering, directed distomedially and slightly curving around distal end of orifice, crossbar complete. Ooecium prominent, resting on frontal wall of next-distal zooid; circular in outline, perforated over entire surface with tiny pseudopores. Spines lacking. Remarks. The large avicularia having setiform mandibles directed distomedially are typical of H. adunca, which, however, also typically has the proximal margin of the orifice straight. While some zooids in the specimens from Co To have the proximal orificial margin nearly straight, most have a concave, distinctly rounded margin. In addition, the only ooeciate zooid observed has a sharp, raised suboral collar. A key character that helps differentiate among Hippopodina species is the ancestrular complex, which forms a triad in in some species (including H. adunca) but a tetrad in others (Tilbrook 1999, 2006). No ancestrular complex was found in the Co To specimens. Distribution. Broadly distributed in the Indo-West Pacific, ranging from Mauritius westward to Fiji (Tilbrook 2006) and northward as far as Okinawa, Japan (Dick & Grischenko 2017)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 223-224, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp.","Dick, M. H. & Grischenko, A. V. (2017) Rocky-intertidal cheilostome bryozoans from the vicinity of the Sesoko Biological Station, west-central Okinawa, Japan. Journal of Natural History, 51, 141 - 266. https: // doi. org / 10.1080 / 00222933.2016.1253797","Tilbrook, K. J. (1999) Description of Hippopodina feegeensis and three other species of Hippopodina Levinsen, 1909 (Bryozoa: Cheilostomatida). Journal of the Zoological Society of London, 247, 449 - 456. https: // doi. org / 10.1111 / j. 1469 - 7998.1999. tb 01008. x"]}

Tubulipora sp. (Fig. 19A) Material examined. VNMN-0271 (CT-42), on SEM stub with Oncousoecia sp. Measurements. AzOr inside diameter, 0.06���0.10 (0.082 ��0.012) (n = 15). Description. Young colony with about 24 zooids, forming a recumbent lobe. Zooids with openings circular, irregularly polygonal, or transversely elliptical; singly arranged or in connate bundles of two; surface perforated by minute pseudopores. Peristomes probably tall, but broken in most zooids. Ancestrula and reproductive structures not observed. Remarks. Without a more fully developed colony and reproductive structures, this specimen can only tentatively be identified to genus Tubulipora, and not at all to species., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on page 241, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740

Calloporina sigillata Canu & Bassler, 1929 (Fig. 10 B���D) Calloporina sigillata Canu & Bassler, 1929, p. 333, pl. 40, figs 9, 10. Calloporina sigillata: Harmer 1957, p. 973, pl. 62, fig. 44; Ristedt and Hillmer 1985, p. 137, pl. 3, fig. 5; Tilbrook 2006, p. 216, pl. 47C���E. Calloporina cf. sigillata: Scholz 1991, p. 316. Material examined. VNMN-0241 ( CT-16), VNMN-0242 (CT-30), on SEM stubs. Measurements. AzL, 0.58���0.95 (0.723 �� 0.091); AzW, 0.45���0.64 (0.556 �� 0.055); OrL, 0.12���0.14 (0.124 �� 0.006); OrW, 0.12���0.14 (0.127 �� 0.006) (n = 15, 1). OvL, 0.29���0.36 (0.321 �� 0.021); OvW, 0.33���0.43 (0.405 �� 0.033) (n = 8, 2). Ancestrula: L �� W, 0.485 �� 0.294; opesia L �� W, 0.226 �� 0.187 (n = 1). Description. Colony unilaminar, encrusting, sheet-like. Zooids large, distinct, irregularly hexagonal, delineated by deep furrow. Frontal wall highly convex; nodulose; eight to 12 areolar pores close to margin and another, less numerous row of pseudopores inset from margin. Orifice subterminal, elevated; subcircular, proximal margin concave; small shelf-like condyles sometimes evident in proximolateral corners; with seven (n = 5) or eight (n = 6) oral spine bases in arc laterally and distally around orifice. Ascopore roughly in center of zooid, circular, surrounded by rim. Large adventitious avicularia proximolateral to orifice, rostrum long, tapering, extending to either side of orifice; usually paired, but sometimes single or lacking; when paired, usually (but not always) unequal in size; rostrum parallel-sided or tapering, distal end acute. Ooecium prominent, broader than long, with transversely oriented, C-shaped ridge covered by non-calcified ectooecium (?), exposing minutely perforate endooecium (?) after bleaching, open end of ���C��� facing proximally; frontal calcification from next-distal zooid forming broad, smooth peripheral band around ooecium laterally and distally; two spine bases visible on each side of orifice proximal to ooecium. Ancestrula tatiform, with numerous spines; one avicularium observed but spine count not possible; initially budding distal (and one distolateral?) zooid, followed by spiral budding pattern on one side. Remarks. This species is readily distinguished from congeners by its large zooids; more than one series of marginal pores; seven or eight oral spines; the smooth proximal orifical margin; large, acute, usually paired frontal avicularia proximolateral and lateral to the orifice, directed distally or distolaterally, unequal in size when paired; the rimmed, circular ascopore in the center of the zooidal area, distant from the orifice; and the ooecium with a Cshaped, minutely perforate transverse ridge. Distribution. Originally described from the Philippines (Canu & Bassler 1929), this species has subsequently been reported from Tizard Bank in the Spratly Islands; Taiwan Strait; Sumbawa, Indonesia; the Great Barrier Reef, western Australia; and the Solomon Islands (Tilbrook 2006)., Published as part of 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, pp. 201-252 in Zootaxa 4747 (2) on pages 224-225, DOI: 10.11646/zootaxa.4747.2.1, http://zenodo.org/record/3694740, {"references":["Canu, F. & Bassler, R. S. (1929) Bryozoa of the Philippine region. United States National Museum Bulletin, 100, I-XI + 1 - 685.","Harmer, S. F. (1957) The Polyzoa of the Siboga Expedition, part 4, Cheilostomata Ascophora II. Siboga Expedition Reports, 28 d, 641 - 1147, pls. 42 - 74.","Ristedt, H. & Hillmer, G. (1985) The cheilostomate bryozoan fauna from shallow waters of the Hilutangan Channel, Cebu, Philippines: part 1. The Philippine Scientist, 22, 133 - 143.","Tilbrook, K. J. (2006) Cheilostomatous Bryozoa of the Solomon Islands. Santa Barbara Museum of Natural History, Santa Barbara, 386 pp."]}