Abyssoecia elevata, 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 : 25-29

Abyssoecia elevata n. sp.

( Figs 2G, H , 13–15 )

Material examined. Holotype: ZIRAS 1/50703, colony detached from nodule, YMG R.V. Yuzhmorgeologiya cruise YMG4–13, Stn 302, 30 July 2014, 13.16460° N, 132.52885° W, 4934 m. Paratype 1: ZIRAS 2/50704, colony detached from nodule, YMG R.V. Yuzhmorgeologiya cruise YMG4–06, Stn 106, 2 September 2006, 13.26750° N, 134.51797° W, 4805 m. Paratype 2: ZIRAS 3/50705, colony attached to particle of nodule, YMG R.V. Gelendzhik cruise GLD4–09, Stn 191, 3 January 2011, 13.40957° N, 133.47513° W, 4897 m. Paratype 3: ZIRAS 4/50706, colony fragment (with gonozooid) detached from nodule, YMG R.V. Yuzhmorgeologiya cruise YMG4–13, Stn 282, 12 July 2014, 13.41580° N, 132.28818° W, 4946 m. Additional material: YMG4–04, Stn 44; YMG4–06, Stn 99; YMG4–07, Stns 129, 135; GLD4–09, Stn 196; YMG4–13, Stn 313. Total specimens examined 11.

Etymology. Latin, elevatus, raised, alluding to the elevation of colony above the substratum.

Description. Colony suberect to erect, flabellate ( Fig. 13 ), pale lemon yellow ( Fig. 2G, H ), supported by founding zooids and additional pillars derived from autozooids ( Figs 13B, F , 15C–I ); up to 5.77 mm long and 9.09 mm wide. Arcuate lateral margins of large colonies tending to curve proximad, occasionally meeting around a space or spaces, creating open calyciform shape ( Figs 2G , 13A ). Supportive pillars of about 4–8 connate zooids, each budded in such a way as to be bent, with proximal portion subvertical, descending towards substratum (e.g. Fig. 15F ), and frontodistal part forming peristomial tubes (e.g. Fig. 15I ). No kenozooids. Surface calcification of colony forming sinuous concentric striae ( Figs 13D , 14A, E–J ) and having fibrous (planar-spherulitic) microstructure ( Fig. 14K ); pseudopores small, simple, sparse, evenly distributed.

Frontal surface with evenly distributed autozooidal peristomes, all obliquely inclined in direction of colony growth, generally longer towards colony margin, fully formed apertures mostly circular ( Fig.14J ), calcified terminal diaphragms rare. New zooids budded from part of distobasal wall of preceding zooid ( Fig. 14G, H ), hence zooids partly overlapping. Interior wall surface of imbricated foliated fabric of wedge-shaped crystallites; no spinules ( Fig. 14K ).

Gonozooid simple, transversely reniform ( Fig. 14A ), wedged in among autozooidal peristomes at colony margin, moderately densely pseudoporous, narrow ooeciostome directed outwards, with more or less circular ooeciopore ( Fig. 14B–E ).

Ancestrula ( Figs 14L–N , 15D–I, K ), suberect, inclined at 50–60° angle to substratum. Protoecium typically flared at base, narrowing at base of peristome but no distinction in surface calcification of needle-like crystallites; peristome tending to be angled to one side ( Figs 14L , 15H, I ). Later daughter zooids tending to form descending outgrowths to substratum, helping to support ancestrula as colony grows; no basal kenozooids.

Measurements (mm). Holotype, ZIRAS 1/50703 ( Fig. 13A–B ): Colony length 3.28, width 4.88, height 2.79; ZL 0.597–0.802 (0.711 ± 0.074); PeL 0.062–0.191 (0.108 ± 0.037); PeD 0.148–0.185 (0.171 ± 0.012); ApL 0.136–0.165 (0.149 ± 0.008); ApW 0.124–0.143 (0.133 ± 0.006).

Paratype 3, ZIRAS 4/50706 ( Fig. 14A–E ): Gonozooid (n = 1): GZL 0.703; GZW 0.880; GZH 0.383; OsL 0.155; OsD 0.133; OpD 0.111.

Non-type specimen YMG4–04, Stn 44 ( Figs 14L–M , 15G–K ): Ancestrula (n = 1): AnH 0.903; AnPeD 0.221; AnPrL 0.247; AnPrW 0.234.

Remarks. Eleven colonies, representing a range of sizes, were isolated from the nodule samples; only one was fertile. The elevated, flabellate form of the colony is consistent, with the pillar-like supports providing stability as the colony expands.

Distribution. Recorded from 10 stations within coordinates 13.09421– 13.49873° N, 130.80695– 134.72239° W, at depth range 4787–5050 m.

Figures

FIGURE 2. Colonies of some cyclostome bryozoans, in vivo, attached to polymetallic nodules. A–E, Pandanipora helix n. gen., n. sp.: A, specimen GLD4–09, Stn 190; B, specimen GLD4–12, Stn 262; C, specimen YMG4–07, Stn 143; D, specimen YMG4–13, Stn 295; E, specimen GLD 4–11, Stn 212. F, Tubuliporina sp. indet., specimen YMG18–01, Stn 7. G, H, Abyssoecia elevata n. gen., n. sp.: G, specimen GLD4–09, Stn 196; H, specimen GLD4–09, Stn 191. I, Discantenna metallica n. sp.: specimen GLD4–11, Stn 224. J, K, Frontohornera frontalis n. gen., n. sp.: J, specimen YMG4–07, Stn 124; K, specimen GLD4–11, Stn 210. L, Alyonushka hystricosa n. gen., n. sp.: specimen GLD4–09, Stn 199. M, Calyssopora volcano n. gen., n. sp.: specimen YMG18–01, Stn 33. N, O, Anyuta anastema n. gen., n. sp.: N, specimen GLD4–09, Stn 180; O, specimen YMG4–06, Stn 71. Scale bars: 1 mm.

FIGURE 13. Abyssoecia elevata n. gen., n. sp. Holotype and paratype colonies detached from their substrata. A, B, holotype, ZIRAS 1/50703, frontal and profile views; note foramen in colony formed by growth and fusion of lobes around a space; C, D, paratype 1, ZIRAS 2/50704 frontal and abfrontal views; E, F, paratype 2, ZIRAS 3/50705, frontal and profile views. Scale bars: 500 µm.

FIGURE 14. Abyssoecia elevata n. gen., n. sp. A–E, paratype 3, ZIRAS 4/50706; F, specimen YMG4–06, Stn 106; G, J, specimen YMG4–13, Stn 302; H, I, N, specimen YMG4–07, Stn 129; K, specimen GLD4–09, Stn 191; L, M, specimen YMG4–04, Stn 44. A, gonozooid at upper left of image with projecting ooeciostome; B, D, distal and distolateral views of gonozooid; C, E, frontal and distal views of ooeciostome with subcircular ooeciopore; F–H, distolateral (F) and distal views of colony margin with developing zooids; I–K, frontal views of short autozooidal peristomes; L–N, ancestrular region of two colonies. Scale bars: A, 500 µm; B, D, F–J, L–N, 200 µm; C, E, 100 µm; K, 50 µm.

FIGURE 15. Abyssoecia elevata n. gen., n. sp. Progressive stages of development of young ancestrulate colonies viewed from different angles, showing development of either supportive columns or growth of lateral margins towards substratum as colony grows larger. A–C, specimen GLD4–09, Stn 196; D–F, specimen YMG4–07, Stn 129; G–L, specimen YMG4–04, Stn 44. Scale bars: A, B, D–F, 250 µm; C, 200 µm; G–L, 500 µm.