Alyonushka filia, Grischenko & Gordon & Melnik, 2018

Grischenko, Andrei V., Gordon, Dennis P. & Melnik, Viacheslav P., 2018, Bryozoa (Cyclostomata and Ctenostomata) from polymetallic nodules in the Russian exploration area, Clarion - Clipperton Fracture Zone, eastern Pacific Ocean-taxon novelty and implications of mining, Zootaxa 4484 (1), pp. 1-91 : 36-40

Alyonushka filia n. sp.

( Figs 21–23 , 52 )

Material examined. Holotype: ZIRAS 1/50710, colony attached to particle of nodule, YMG R.V. Gelendzhik cruise GLD4–08, Stn 164, 4 August 2009, 13.26703° N, 133.84563° W, 4922 m. Paratype: NIWA 127724, colony attached to particle of nodule, YMG R.V. Yuzhmorgeologiya cruise YMG4–07, Stn 123, 31 July 2007, 13.29668° N, 134.17724° W, 4774 m. Additional material: YMG4–04, Stn 48; GLD4–08, Stn 156; GLD4–09, Stns 173, 180, 195; GLD4–11, Stns 222, 224, 227; GLD4–12, Stns 235, 236; YMG4–13, Stns 294, 299, 319; YMG4–14, Stns 351, 357, 363, 365. Total specimens examined 19.

Etymology. Latin, filia , daughter, linking with the genus name; used as a noun in apposition.

Description. Colony erect, pedunculate and subcalyciform, with outwardly flaring capitulum of relatively long autozooidal peristomes in mature colonies ( Fig. 21A, B ), up to maximum of c. 27 long and short peristomes in single irregular whorl; lower parts of some peristomes fused with shorter neighbors in slightly more abfrontal position. Calyx center in immature colonies bowl-like with a few relatively large peripheral alveoli. Column narrowest in middle, widening evenly to moderately broad base. Entire external skeletal surface of colony minutely and excessively prickled ( Fig. 22F–J, L ). Skeletal microstructure of generally irregular angular imbricated crystallites ( Fig. 22E ). Proximal half of column may become thickened by development of layers of overlapping flattened, cushion-like alveoli/kenozooid-like chambers.

Autozooidal peristomes with staggered barbed ridges ( Figs 21 , 22A–D ). Pores simple, small, sparse ( Fig. 22D ). Apertures rounded, the rims bearing up to 10 evenly spaced projections of peristomial ridges ( Fig. 22A, C–E, I, K ). Interior of peristomes with simple scattered spinules ( Fig. 22K ); these longer and more acicular in openings of developing zooids ( Fig. 22F ).

Gonozooids 1–2 per mature colony ( Figs 21A–C , 22A ), occupying calyx center, large, convex; surface highly irregular owing to rims of adjacent alveoli bearing irregularly oriented thorn-like processes ( Figs 21C , 22B ), all minutely prickled ( Fig. 22G ). Incubation-chamber floor continuous ( Figs 21E , 52C ). Ooeciostome(s) relatively broad and low, ooeciopore subrounded, very little elevated, thin-walled; inner face with sparse granulation ( Fig. 22J, L ). CT scans show narrow shelf within ooeciostome at inner entrance to gonozooid ( Fig. 52C ).

Ancestrula not seen in isolation, but erect judging from smallest (four-zooid) colony stages seen ( Fig. 23A–J ); CT scans confirm protoecial dome with erect peristome arising from its center, with first daughter zooid also produced from dome adjacent to it ( Fig. 52D, E ). Low trabeculae form in center of developing colony to support continuing elevation and expansion, with extrazooidal alveolar spaces between trabeculae and kenozooid-like chambers supporting stem.

Measurements (mm). Holotype, ZIRAS 1/50710 ( Fig. 21A, B ): Colony height 3.20; capitulum 2.44 × 1.86; attachment base 1.15 × 1.03; stalk height 1.71, thickness 0.45 × 0.41 to 0.80 × 0.77; ZL 0.932–1.238 (1.062 ± 0.102); PeL 0.593–1.055 (0.812 ± 0.138); PeD 0.151–0.173 (0.160 ± 0.007); ApL 0.130–0.154 (0.143 ± 0.009); ApW 0.103–0.125 (0.116 ± 0.007). Gonozooid 1 (n = 1): GZL 0.695; GZW 0.410; OsL 0.123; OsW 0.101. Gonozooid 2 (n = 1): GZL 0.780; GZW 0.558; OsL 0.130; OsW 0.116.

Non-type specimen GLD4–09, Stn 173 ( Fig. 23A, B ): AnPeD 0.123 (n = 1).

Remarks. Alyonushka filia n. gen., n. sp. is distinguished from the following two new species by its much longer, barbed, peristomes and spinose apertures, as well as the chaotic thorny surface of its gonozooid(s).

Distribution. Recorded from 19 stations within coordinates 12.55585– 14.57215° N, 130.83310– 134.17724° W, at depth range 4774–5275 m.

Figures

FIGURE 21. Alyonushka filia n. gen., n. sp. A, holotype, ZIRAS 1/50710, profile of colony with paired gonozooid; B, paratype, NIWA 127724, profile of colony with single gonozooid; C–E, specimen YMG4–13, Stn 299, bilaterally compressed, showing developing gonozooid with continuous floor. Scale bars: A, B, 500 µm; C–E, 250 µm.

FIGURE 22. Alyonushka filia n. gen., n. sp. A–E, G–L, holotype, ZIRAS 1/50710; E, F, paratype, NIWA 127724. A, frontal (apical) view of colony showing two gonozooids separated by a narrow cleft, each chamber with an ooeciopore (arrows); B, oblique view of A from 8 o’clock perspective, showing two gonozooid mounds separated by cleft (concealed in furrow), each mound with complex spiky alveolate surface; C, same, from different angle, cleft at middle left; D, autozooidal peristomes with linear ridges and barbs, and pores; E, skeletal microstructure of gonozooid surface; F, I, incompletely developed autozooidal peristomes with abundant internal spinules; G, close-up of part of cleft between adjacent gonozooids; H, base of colony with hummocks indicating underlying alveolar/kenozooid-like chambers; note densely prickled surface; J, L, ooeciostomes of the two gonozooids shown in A; K, apical view of mature autozooidal peristome. Scale bars: A, 500 µm; B–D, H, 250 µm; F, G, I, J, L, 100 µm; E, K, 50 µm.

FIGURE 23. Alyonushka filia n. gen., n. sp. Progressive stages of development of ancestrulate and slightly older colonies. A, B, specimen GLD4–09, Stn 173, at four-zooid stage, with alveoli; C, D, specimen YMG4–14, Stn 363, four-zooid colony with one peristome occluded and spikes on trabeculae; E, F, specimen GLD4–11, Stn 224, also at four-zooid stage but with broader base; G, H, specimen YMG4–14, Stn 365 with more-convex colony center; I, J, specimen YMG4–14, Stn 351, nearsymmetrical four-zooid colony; K, L, specimen GLD4–09, Stn 180, colony with disproportionately thickened base and irregular column margin, suggesting possible regeneration after damage; M, N, specimen GLD4–12, Stn 235, an asymmetrical five-zooid colony; O, P, specimen YMG4–13, Stn 294, with unusually thick basal support. Scale bars: 200 µm.

FIGURE 52. Alyonushka filia n. gen., n. sp. Micro-CT scans of paratype, NIWA 127724, as back-face isosurface renders showing colony interiors. A, entire colony in profile; note the density of kenozooidal chambers in the column; B, close-up of distal part of column showing diminished numbers of kenozooids where it broadens into the calyx; C, optical section through gonozooid and ooeciostome, with arrowhead indicating a ledge at inner opening of ooeciostome; D, optical section through base of column showing protoecial dome with ancestrular peristome emerging from its apex (purple) and first daughter zooid (red) also originating from protoecium (its communication pore outside plane of section); note multiple layers of kenozooids; E, three successive sections through ancestrular region, moving upwards from left to right, respectively showing protoecium (red) and first daughter zooid (yellow), narrowing to ancestrular peristome and broadening peristome of daughter zooid. Scale bars: A, B, 250 µm; C–E, 100 µm.