Alyonushka echinata, 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 : 41-43

Alyonushka echinata n. sp.

( Figs 26 , 27 )

Material examined. Holotype: ZIRAS 1/50712, colony attached to nodule particle, YMG R.V. Yuzhmorgeologiya

cruise YMG4–13, Stn 288, 26 July 2014, 12.94712° N, 132.54418° W, 5056 m. Paratype: ZIRAS 2/50713, colony attached to particle of nodule, YMG R.V. Gelendzhik cruise GLD4–11, Stn 206, 18 April 2012, 13.47733° N, 133.02290° W, 4824 m. Total specimens examined two.

Etymology. Latin, echinatus, spiny, prickly, alluding to the minutely prickled colony surface.

Description. Colony erect, pedunculate and subcalyciform, with outwardly flaring capitulum of seven short autozooidal peristomes ( Fig. 26 ), in single whorl. Column of more or less equal diameter to base or broadening somewhat at base, thickened, with small, shallow alveolar chambers at surface ( Fig. 26A ). Entire external skeletal surface of colony covered by tiny minutely branching prickles ( Fig. 27K ), except for distal part of peristomial surface where prickles are a little less complex ( Fig. 27H ). Pores simple, most evident on outer surface of peristomial tubes ( Fig. 26C, F ).

Surface of autozooidal peristomes with crystallites aligned into coarse, upwardly directed micro-nodules ( Fig. 27E ); skeletal ultrastructure of generally narrow, irregular imbricated crystallites. Aperture subrounded, rim granulated or prickled, inner surface of peristomes also with simple and minutely branching prickles/spinules ( Fig. 27I, J ).

Gonozooid ( Figs 26A–F , 27A–D ) occupying calyx center, large, slightly convex, with sparsely distributed tiny openings of alveoli, centrally imperforate, surrounded by irregular alveoli around periphery. Ooeciostome(s) difficult to discriminate from larger alveoli; one broken, one more evident ( Fig. 27B, F, G ), very short with thin prickled rim, inner surface with sparse low irregularities. Ooeciopore much smaller than autozooidal apertures.

Ancestrula and very small colonies not seen.

Measurements (mm). Holotype, ZIRAS 1/50712 ( Fig 26A–C ): Colony height 1.54; capitulum 1.02 × 0.66; base at substratum 0.41 × 0.51; ZL 0.331–0.478 (0.386 ± 0.049) (n = 7); PeL 0.144–0.303 (0.204 ± 0.059) (n = 7); PeD 0.153–0.178 (0.163 ± 0.009) (n = 7); ApL 0.121–0.153 (0.135 ± 0.013) (n = 7); ApW 0.098–0.133 (0.114 ± 0.014) (n = 7); OpD 0.044 (n = 1).

Remarks. Alyonushka echinata n. sp. is most readily distinguished from the type species by its short peristomes with a less-barbed lineated surface texture, and the form of the gonozooid and its openings. It differs most obviously from A. hystricosa n. sp. in that the interior walls of zooidal peristomes are prickled, not smooth.

Distribution. Recorded from two stations within coordinates 12.94712– 13.47733° N, 132.54418– 133.02290° W, at depth range 4824–5056 m.

Figures

FIGURE 26. Alyonushka echinata n. gen., n. sp. A–C, holotype, ZIRAS 1/50712, rotational views of fertile colony; D–F, paratype, ZIRAS 2/50713, rotational views of fertile colony. Arrows indicate the ooeciostome in all photos. Scale bars: 250 µm.

FIGURE 27. Alyonushka echinata n. gen., n. sp. Details of morphology. A, C, H, K, holotype, ZIRAS 1/50712; B, D–F, G, I, J, paratype, ZIRAS 2/50713. A, C, apical and oblique views of calyx with gonozooid (ooeciostome arrowed); note variable sizes of alveolar openings; B, D, oblique and near-profile views of calyx with gonozooid, with broken entrance to gonozooid arrowed; E, skeletal ultrastructure of outer peristomial wall; F, G, close-ups of broken entrance to gonozooid; H, lateral view of zooidal peristome with simpler spiky structures than those more proximal at calyx surface; I, J, spinules on interior walls of peristomes; K, variable alveolar openings and spinose texture of gonozooid surface. Scale bars: A–D, 200 µm; E–G, 100 µm; H–K, 50 µm.