Rhamphostomella tatarica ( Androsova, 1958 )

Grischenko, Andrei V., Gordon, Dennis P., Taylor, Paul D., Kuklinski, Piotr, Denisenko, Nina V., Spencer-Jones, Mary E. & Ostrovsky, Andrew N., 2022, Taxonomy, ecology and zoogeography of the Recent species of Rhamphostomella Lorenz, 1886 and Mixtoscutella n. gen. (Bryozoa, Cheilostomata), Zootaxa 5131 (1), pp. 1-115 : 67-70

publication ID	https://doi.org/ 10.11646/zootaxa.5131.1.1
publication LSID	lsid:zoobank.org:pub:CF550031-D6A9-48A3-A953-A1BD40C72F5E
DOI	https://doi.org/10.5281/zenodo.6520699
persistent identifier	https://treatment.plazi.org/id/03892374-0B75-3378-FF73-A8371DCCFD15
treatment provided by	Plazi
scientific name	Rhamphostomella tatarica ( Androsova, 1958 )
status

Treatment

Rhamphostomella tatarica ( Androsova, 1958) View in CoL

( Figs 20 View FIGURE 20 , 33C, D View FIGURE 33 )

Escharopsis tatarica Androsova, 1958, p. 168 View in CoL , fig. 98.

Escharopsis tatarica: Kluge et al. 1959, p. 213 View in CoL ; Kluge 1961, p. 141.

Posterula tatarica: Denisenko 2013, p. 185 .

Material examined. Holotype: ZIRAS 1 /3701, single colony, RV Toporok , Stn 12, 6 July 1947, eastern Tatar Strait , coastal waters of southern Sakhalin Island, Sea of Japan, depth 117 m, boulders, beam-trawl, collector Z.I. Kobjakova. Paratype: ZIRAS 2 /3852, single colony , RV Toporok , Stn 29, 21 August 1949, Tatar Strait, Sea of Japan, depth 43 m, silted sand with shells, dredge, collector Z.I. Kobjakova.

ZIRAS 7 /50548, two colony fragments , MFRT Rodino, 12 September 1992, about 32 km from Cape Hayryuzova, western Kamchatka shelf, Sea of Okhotsk , 57°36.2ʹ N, 156°09.0ʹ E, depth 78–81 m, crab trap, collector A GoogleMaps . V. Grischenko .

Measurements. ZIRAS 7/50548, western Kamchatka, Sea of Okhotsk ( Fig. 20A–M View FIGURE 20 ). ZL, 0.82–1.20 (1.01 ± 0.10). ZW, 0.37–0.78 (0.53 ± 0.07). ZD, 0.43–0.54 (n = 2). OrL, 0.21–0.29 (0.25 ± 0.02). OrW, 0.24–0.31 (0.28 ± 0.02). OeL, 0.29–0.36 (0.31 ± 0.02) (n = 10). OeW, 0.39–0.45 (0.42 ± 0.02) (n = 10). Av(s)L, 0.13–0.20 (0.16 ± 0.02). P(m)N, 19–30 (25). P(oe)N, 9–18 (15) (n = 10).

Description. Colonies encrusting, multiserial, unilaminar ( Fig. 20A View FIGURE 20 ), irregular in form; largest among our fragments was about 13 × 7 mm; bright brown when alive, light brown when dry. Zooids large, oblong hexagonal, pyriform, rectangular or irregular in shape ( Fig. 20A, D–G View FIGURE 20 ), arranged in checkered pattern, demarcated by fine sinuous sutures between lateral and transverse walls recognizable in all colony parts.

Frontal shield umbonuloid ( Fig. 20A View FIGURE 20 ), thin, dimpled with reticulate appearance, flat or moderately convex in young zooids ( Fig. 20A, D View FIGURE 20 ), becoming more convex in older zooids ( Fig. 20E–G View FIGURE 20 ). Frontal shield with angular marginal areolae ( Fig. 20A, B, D–H View FIGURE 20 ), separated by short narrow interareolar ridges in young zooids ( Fig. 20A, D View FIGURE 20 ), becoming more elongate and distinctly larger with age and, thus occupying noticeably larger area on frontal shield ( Fig. 20F–H View FIGURE 20 ). Umbonuloid component very extensive, occupying about 90% of length of frontal shield (89% in one measured zooid), with fine parallel lineation and accretionary banding ( Fig. 20I View FIGURE 20 ). Ring scar indistinct ( Fig. 20I, L View FIGURE 20 ).

Primary orifice ( Fig. 20A, B, J View FIGURE 20 ) submerged, transversely oval; distal and lateral margins formed by upper terminal part of distal transverse wall, bearing wide, flared shelf distally ( Fig. 20A–C View FIGURE 20 ). Distal margin of orifice shallowly rounded, proximal margin with median oval sinus flanked by blunt or acute projection on each side ( Fig. 20A–C, J View FIGURE 20 ). Condyles absent.

Secondary orifice ( Fig. 20C View FIGURE 20 ) transversely oval, with deep, median U-shaped sinus in proximal margin, cormidial; sinus formed by ridges flanking primary orifice that continue into peristome, forming prominent peristomial “denticle” on one side and another “denticle” from proximo-interior corner of suboral avicularian cystid on other. Secondary orifice distally formed by vertical concave thickening of proximal shield of daughter zooid ( Fig. 20B– D View FIGURE 20 ), proximally restricted by thin-walled peristome incorporating cystid of suboral avicularium on one side and high lappet with terminal denticle on opposite side. In ovicellate zooids, avicularian cystid and lappet both connecting to proximolateral corners of ooecium ( Fig. 20E View FIGURE 20 ). Extensions of lateral walls of contiguous distolateral zooids growing as secondary calcification over ooecium, as two converging lobes that sometimes meet. Together with peristomial lappet and avicularian cystid, these lobes forming complete or incomplete circle ( Fig. 20F–H View FIGURE 20 ), conferring tubular, transversely oval to irregular outline to peristomial orifice. No oral spines.

Cystid of suboral avicularium small, slightly elevated, with dimpled surface and one communication pore ( Fig. 20A–H View FIGURE 20 ), asymmetrically placed proximally on left or right of orificial margin and slightly overhanging it. Frontal surface (rostral/postmandibular areas) of avicularium to one side of zooidal midline, facing distally or obliquely upwards. Rostrum lingulate, with slightly curved distal end, directed distolaterally ( Fig. 20B–H View FIGURE 20 ), extending over surface of neighbouring zooid ( Fig. 20D–G View FIGURE 20 ). Palate lingulate, foramen elongate oval with distal cryptocystal shelf; opesia semicircular. Crossbar complete.

No adventitious avicularia.

Ovicells initially hyperstomial, rapidly becoming subimmersed and sometimes appearing endozooidal through overgrowth of ooecium by secondary calcification encroaching from walls of surrounding lateral and daughter zooids ( Fig. 20F–H View FIGURE 20 ). Ooecium formed by distal autozooid, ooecial fold developing at colony periphery concurrently with formation of frontal shield of distal zooid. Ooecium smooth ( Fig. 20F–H View FIGURE 20 ), with scattered circular or oval pseudopores, some occluded by secondary calcification; proximal margin arched.

Zooids interconnected by 2‒3 mural pore chambers in each distolateral wall ( Fig. 20M View FIGURE 20 ) and two multiporous septula (sometimes with individual pores in between) in basal half of transverse walls ( Fig. 20B View FIGURE 20 ).

Basal wall of zooids fully calcified, smooth, flattened, with fine transverse parallel lineation in places ( Fig. 20K View FIGURE 20 ). Boundaries between zooids visible basally as fine, sinuous incisions.

Ancestrula and early astogeny not observed.

Remarks. Androsova (1958) attributed her new species to Escharopsis Verrill, 1880 based solely on the absence of a lyrula in the primary orifice. At the same time, Escharopsis lacks evenly pseudoporous ooecia; instead, there are either no pseudopores or just a single central pseudopore. Denisenko (2013) placed this species in Posterula Jullien, 1903 , but the peristomial secondary orifice with an asymmetrically set suboral avicularium and ovicells with numerous pseudopores warrant placement of this species in Rhamphostomella .

Ecology. Rhamphostomella tatarica has been recorded from depths of 30–117 m, on gravel and mollusc shells.

Distribution. The species was originally described from the northern part of the Sea of Japan, including off Kholms, Tomari, Ilyinskoye and Belinskoye along the southwestern coast of Sakhalin Island (47°03.0ʹ N, 142°00.0ʹ E to 48°15.0ʹ N, 142°08.0ʹ E) and from Primorye near capes Zolotoy (47°18.0ʹ N, 139°00.0ʹ E) and Syurkum (50°05.0ʹ N, 140°41.0ʹ E). It was subsequently reported by Kluge et al. (1959) and Kluge (1961) from the western part of southern Sakhalin and at Primorye. We obtained specimens from the western Kamchatka shelf of the Sea of Okhotsk. Based on these records, R. tatarica is a Pacific Asian high-boreal, sublittoral species.