Alyonushka echinata

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. 26 A). Entire external skeletal surface of colony covered by tiny minutely branching prickles (Fig. 27 K), except for distal part of peristomial surface where prickles are a little less complex (Fig. 27 H). Pores simple, most evident on outer surface of peristomial tubes (Fig. 26 C, F). Surface of autozooidal peristomes with crystallites aligned into coarse, upwardly directed micro-nodules (Fig. 27 E); 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. 27 I, J). Gonozooid (Figs 26 A – F, 27 A – 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. 27 B, 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 26 A – 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.

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

Material examined. Holotype: ZIRAS 1 / 50712, colony attached to nodule particle, YMG R. V. Yuzhmorgeologiya cruise YMG 4 – 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 GLD 4 – 11, Stn 206, 18 April 2012, 13.47733 ° N, 133.02290 ° W, 4824 m. Total specimens examined two.