Saccocamera ampulla, 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 : 33-34

Saccocamera ampulla n. sp.

( Figs 19 , 20 )

Material examined. Holotype: ZIRAS 1/50709, colony attached to nodule particle, YMG R.V. Yuzhmorgeologiya cruise YMG4–14, Stn 359, 19 January 2016, 14.08687° N, 131.78558° W, 5122 m. One specimen only.

Etymology. Latin, ampulla , bottle, flask, alluding to the shape of the gonozooid; used as a noun in apposition.

Description. Colony squat, tiny, on very short base showing alveoli around periphery, no surrounding lamina ( Fig. 19 ), 1.72 × 1.51 mm, 1.39 mm high. Alveoli with uneven openings of various sizes; these surround incubation chamber in sole fertile colony. Colony center encircled by two whorls of autozooidal peristomes. Entire surface minutely granular-tubercular, some granules longer and minutely prickle-like ( Fig. 20F–J ). Pores tiny, rare.

Autozooidal peristomes moderately long in uppermost whorl, shorter below, each with bumpy discontinuous longitudinal ridges, some barbed ( Fig. 20H ). Apertures subcircular to oval with up to eight spines ( Fig. 20J, K ), each representing distal extension of longitudinal ridge. Inner surface of peristome more or less smooth, lacking spinulation ( Fig. 20K ).

Gonozooid single, prominent, saccular, highly convex, occupying almost entire center of colony ( Figs 19A–D , 20A ). Surface minutely prickly-granular ( Fig. 20C–E ), lacking pores or surficial alveoli. Ooeciostome like neck of flask, narrowed but slightly flared at rim ( Fig. 20C, D ), ooeciopore transversely oval ( Fig. 20E ), inner surface slightly ridged and textured, but no spinulation.

Ancestrula and early astogeny not seen.

Measurements (mm). Holotype, ZIRAS 1/50709 ( Fig. 19A–D ): ZL 0.353–0.653 (0.509 ± 0.108); PeL 0.268–0.563 (0.438 ± 0.102); PeD 0.170–0.203 (0.185 ± 0.012); ApL 0.148–0.201 (0.178 ± 0.016); ApW 0.121–0.155 (0.140 ± 0.012). Gonozooid (n = 1): GZL 0.718; GZW 0.674; GZH 0.379; OsL 0.063; OsW 0.196; OsH 0.183; OpL 0.131; OpW 0.159.

Remarks. The gonozooid of Saccocamera ampulla n. sp. resembles that illustrated in Moyano’s (1991) line drawings of S. minima in terms of its proportions and placement relative to the rest of the colony, but he illustrated a much smaller ooeciopore. Saccocamera minicamera can have two calyces of autozooids per colony and the gonozooid is even more discrete, with no ooeciostome as such, just a wide ooeciopore. Saccocamera minutissima , which has the smallest-known mature colony of any cyclostome (perhaps of any skeletonized bryozoan), has just five autozooidal peristomes surrounding a tiny chamber with a minute ooeciostome and ooeciopore.

Distribution. Recorded from a single station with coordinates 14.08687° N, 131.78558° W, at 5122 m depth.

Figures

FIGURE 19. Saccocamera ampulla n. gen., n. sp. A–D, four profiles of fertile holotype colony, ZIRAS 1/50709, YMG4–14, Stn 359. Scale bars: 250 µm.

FIGURE 20. Saccocamera ampulla n. gen., n. sp. Holotype, ZIRAS 1/50709. A, Frontal (apical) view of gonozooid, with peristome at 4 o’clock; B, lateral view of gonozooid, peristome directed to right; note the numerous alveolar openings; C, D, gonozooid showing lageniform ooeciostome; E, ooeciopore; F–J, profiles of autozooidal peristomes showing surface texture and spinose processes; K, autozooidal aperture. Scale bars: A, B, 200 µm; C, D, F–J, 100 µm; E, K, 50 µm.