Vasopora ceramica Grischenko & Gordon & Melnik 2021, n. sp.
Creators: name: Grischenko, Andrei V.
name: Gordon, Dennis P.
name: Melnik, Viacheslav P.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Bryozoa
Stenolaemata
Cyclostomatida
Alyonushkidae
Vasopora
Vasopora ceramica

description: Vasopora ceramica n. sp.
(Figs 2–4)
Genus et species indet.: Grischenko, Gordon & Melnik 2018: p. 55, figs 36–38.
Material examined. Holotype: ZIRAS 1 /50740, colony attached to nodule particle, YMG R. V. Gelendzhik cruise GLD4–19, Stn 421, 8 February 2021, 13.23408° N, 134.22180° W, 4809 m. Paratype 1: ZIRAS 2 /50738, colony (‘colony 1’ in Grischenko et al. 2018, p. 55, figs 36A, B, 37A, D, F, G), attached to nodule particle, YMG R. V. Gelendzhik cruise GLD4–11, Stn 211, 21 April 2012, 13.27820° N, 133.05707° W, 4846 m. Paratype 2: ZIRAS 3 /50739, colony (‘colony 2’ in Grischenko et al. 2018, p. 55, figs 36C, D, 37B, C, E, H, I), attached to nodule particle, YMG R. V. Gelendzhik cruise GLD4–12, Stn 255, 8 April 2013, 12.91588° N, 132.78325° W, 4801 m. Additional material: YMG18–01, Stn 38; YMG4–06, Stns 80, 81; YMG4–07, Stn 128; GLD4–09, Stns 183, 192; GLD4–12, Stn 272; YMG4–17, Stn 381; GLD4–19, Stn 421. Total specimens examined eleven.
Etymology. Latinized form of Greek keramos, ceramic, alluding to the very smooth, glabrous surface of the colony stalk (column), resembling the surface of a ceramic vase. Gender feminine.
Description. Colony erect, miniature, vasiform, with relatively convex capitulum on proportionately thin and tall column (Figs 2A–D, F, 3A, B). Capitulum:column height ratio 1:3. Capitulum with thin outer rim encircling eight radially orientated autozooidal peristomes and alveoli arranged along periphery (Fig. 2E, F), with centrally located incubation chamber on top (Figs 2E, F, 3A–C). Alveoli immediately inside calyx rim ovoid to slit-like. Much of remainder of capitulum comprising polygonal to subrounded alveoli, their combined rims giving a reticulated appearance (Fig. 2E, F). Entire skeletal surface of capitulum minutely densely granular to subspinulate (Figs 2G‒L, 3D‒H).
Peristomes relatively short, eight in number, directed obliquely outwards at angle of c. 30–65° (Figs 2F, 3A–F). Peristomial rims of a few well-preserved peristomes with six to eight spine-like processes around margin (Figs 2F, 3A–D), each associated with longitudinal ridge on outside of peristomial base (Fig. 3D, E, J–L). Peristomial walls with sparse, simple communication pores (Figs 2G, 3D, E, J‒M). At higher magnification, outer surface constructed of irregular (Fig. 3L) or wedge-shaped crystallites (Fig. 3M).
Gonozooid solitary, capacious, sac-like, domed, swollen, located centrally, with insignificant marginal shift relative to capitulum center, unidirectional (Figs 2E, F, I–L, 3A–C). Ooeciostome negligible, barely discernible, in form of very narrow, densely granulated band of calcification encircling ooeciopore and lacking pores (Fig. 2G, J, K). Ooeciopore (Fig. 2M, N) transversely subcircular, with flatter and straighter upper margin, located on slope of gonozooid, orientated perpendicularly relative to main colony axis, facing outwards (Figs 2F, I–K, 3D, E). Gonozooid with tiny circular pores concentrated on roof and less frequent on lateral and back sides (Fig. 2G‒L). Gonozooid covered by dense network of polygonal ridges (Fig. 2E, H) representing shallow alveoli, continuous with larger, deeper surrounding alveoli. Surface microstructure of gonozooid with imbricated irregular crystallites (Fig. 2O–Q).
Column vase-like, elongated (Fig. 2A–D), 75% of colony height, narrowest in middle, flaring toward base (Fig. 3N) and capitulum. Entire column surface exterior-walled, smooth, glabrous, lacking pseudopores, with traces of regeneration preserved in form of weakly prominent rims with roughly uneven edges (Figs 2A–D, 3N). Skeletal microstructure (Fig. 3O) comprising planar-spherulitic surface fabric of closely appressed acicular to irregular sharp crystallites, clustered into parallel horizontal to oblique strips or fans parallel to wall surface. Upper margin of column (outer rim) even along whole perimeter (Figs 2A–D, 3A–E, G, H), smooth-surfaced, identically to main column surface, locally with gentle undulations in horizontal profile and very short straightening in vertical profile. Basal column margin deeply undulating over entire length (Figs 2A–D, 3N), following irregularities of substratum microrelief.
Early astogeny (examined using non-type specimen, Fig. 4A–F) indicates protoecial dome, rather narrow in diameter (Fig. 4F), with erect ancestrular peristome arising from its entire roof (Fig. 4B, D, F), with first zooid also produced from dome adjacent to it (best seen in Fig. 4E). Multiple elongated to shortened trabeculae occupy periphery of expanded colony base to support continuing elevation and expansion, with greatly variable (tubular, cubical, oval to irregular) extrazooidal alveolar spaces or kenozooid-like chambers supporting base and stem (Fig. 4B, C).
Measurements (mm). Holotype, ZIRAS 1/50740 (Figs 2, 3): Colony height 2.18; capitulum height 0.55; capitulum cross-section 1.16 × 1.06; column height 1.63; base at substratum cross-section 0.93 × 0.80; column narrowest cross-section 0.42 × 0.38; column upper margin (outer rim) cross-section 1.11 × 1.08. ZL 0.306 –0.507 (0.423 ± 0.058) (n = 8); PeL 0.141 –0.306 (0.240 ± 0.050) (n = 8); PeD 0.153 –0.173 (0.163 ± 0.007) (n = 8); ApL 0.143 –0.164 (0.153 ± 0.007) (n = 8); ApW 0.121 –0.134 (0.127 ± 0.004) (n = 8). Gonozooid (n = 1): GZL 0.504; GZW 0.341; GZH 0.357; OpL 0.111; OpW 0.132.
Non-type specimen YMG4–17, Stn 381 (Fig. 4D, E): AnPrD 0.149 (n = 1); AnPeD 0.094 (n = 1).
Remarks. Vasopora n. gen. clearly conforms to the characters of the rectangulate cyclostome family Alyonushkidae in general gross morphology, i.e. in possessing: 1) erect pedunculate colony with flaring capitulum of radially orientated autozooidal peristomes in one irregular level; 2) relatively large incubation chamber located in calyx center and surrounded by alveoli; 3) proximally tapering column to expanded base, incorporating vertically erect ancestrula with peristome arising from apex of protoecial dome (Fig. 4). At the same time, the new genus displays a combination of characters not previously observed in the two earlier-described alyonushkid genera. A comparison shows the following principal differences:
1) Species of Alyonushka and Calyssopora have no distinct structural boundary between the stalk (column) and capitulum, so that the stalk calcification is continuous with that of the capitulum and autozooidal peristomes in both of these taxa; in contrast, in Vasopora n. gen. the capitulum is encircled by a thin outer rim, present at all stages of astogeny, including ancestrulate and young infertile colonies (Grischenko et al. 2018, p. 58, fig. 38), conferring a consistent vasiform appearance, with a clear border between column and capitulum, where the autozooidal peristomes are always trapped inside the edge of the vase-like column. Among CCFZ fungiform cyclostomes, the sharp margin between stalk and capitulum is also known for Discantenna metallica Grischenko, Gordon & Melnik, 2018, but the latter species is tubuliporine, and clearly differs in having a stem with peristomes of feeding zooids between substratum and disk.
2) The reticulate appearance of the gonozooid roof and whole capitulum, giving the appearance of a network of ridges and contrasting with the smooth column, is unknown in any species of Alyonushka and Calyssopora. An alveolate calyx surface with a moderately developed trabeculate network is seen only in C. vasiformis (Grischenko et al. 2018, p. 50, fig. 31) but colonies of the latter species have a wholly dimpled surface over the capitulum and stalk.
3) Colonies of known species of Alyonushka and Calyssopora have a single type of microscopic calcification. Specifically, the entire outer colony surface is minutely prickled in every Alyonushka species, while in Calyssopora it is granular-tubercular (C. volcano), irregularly textured with minute dimples and granules (C. clarionensis), or dimpled (C. vasiformis), but in all cases the surface shows uniform topography for each given species. Microstructurally, the surface of these taxa is nearly identical, with imbricated platy crystallites (see for detail Grischenko et al. 2018, p. 38, fig. 22E; p. 42, fig. 25; p. 44, fig. 27E; p. 48, fig. 29H; p. 50, fig. 31I; p. 53, fig. 34J, K). In contrast, V. ceramica n. gen., n. sp. shows two different types of calcification with two clearly distinguishable forms of crystallites within colony: whereas surfaces of capitulum structures (peristomes, gonozooid, and trabeculate network) are minutely granular to subspinulate, the column surface is exterior-walled, smooth, glabrous and lacking pseudopores. Capitulum microstructure comprises polygonal wedge-shaped crystallites, while that of the column is planar-spherulitic with appressed acicular crystallites, clustered into horizontal to oblique belts or fans parallel to the surface. At the macro-level, these microstructural differences result in the strongly contrasting appearance of capitulum and column.
In sum, the vivid contrast between the coarsely-surfaced reticulate capitulum and perfectly smooth glabrous column, with a clear boundary (rim) between, supplemented with two types of calcification and two forms of crystallites, makes Vasopora ceramica n. gen., n. sp. clearly distinguishable from other alyonushkids and hence a unique taxon among cyclostome genera described from the CCFZ.
Distribution. The newly obtained holotype colony was collected from 13.23408° N, 134.22180° W at 4809 m. Overall, Vasopora ceramica n. gen., n. sp. so far occurs only within the Russian exploration area of the Clarion– Clipperton Fracture Zone from eleven stations (Fig. 1), bounded by coordinates 12.91588 – 13.82842 ° N, 129.06438– 134.73936° W, at 4725–5280 m depth.
description: Published as part of Grischenko, Andrei V., Gordon, Dennis P. & Melnik, Viacheslav P., 2021, Vasopora ceramica n. gen., n. sp. - a new abyssal cyclostome bryozoan from polymetallic nodules in the Russian exploration area, Clarion-Clipperton Fracture Zone, eastern Pacific Ocean, pp. 444-452 in Zootaxa 5047 (4) on pages 446-450, DOI: 10.11646/zootaxa.5047.4.4, http://zenodo.org/record/5543057