Cheilopora sincera ( Smitt, 1868 )

Grischenko, Andrei V., Dick, Matthew H. & Mawatari, Shunsuke F., 2007, Diversity and taxonomy of intertidal Bryozoa (Cheilostomata) at Akkeshi Bay, Hokkaido, Japan, Journal of Natural History 41 (17 - 20), pp. 1047-1161 : 1125-1127

Cheilopora sincera ( Smitt, 1868)

( Figure 31 )

Discopora sincera Smitt 1868, p 28 , 177 (part), Plate 27, Figures 178–180.

Mucronella sincera: Nordgaard 1895, p 29 , Plate 1, Figure 6 .

Eschara sincera: Nordgaard 1905, p 168 , Plate 3, Figures 12–14 .

Cheilopora sincera: Nordgaard 1912, p 21 ; Androsova 1958, p 174, Figure 105; Kluge 1962, p 562, Figure 396; 1975, p 684, Figure 396.

Cheiloporina sincera: Gontar and Denisenko 1989, p 357 ; Gontar 1996, p 46.

Cheilopora sincera var. orientalis Kluge 1952, p 162 , Text figure 15.

Cheilopora orientalis: Kluge 1961, p 142 .

Material examined

ACT, colony on the erect bryozoan Phidolopora elongata (NHM 2006.2.27.77); NB, colony fragment (NHM 2006.2.27.78).

Description

Colony initially encrusting, unilaminar, sheet-like, later rising in erect, meandering expansions, reaching 2 cm in maximum dimension, bright yellow in colour when alive. Zooids ( Figure 31A, B ) hexagonal, barrel-shaped, or rectangular, rounded distally, 0.53– 0.93 mm long (0.73¡ 0.10 mm), 0.33–0.48 mm wide (0.39¡ 0.04 mm), delineated by narrow incision between adjacent vertical walls. Frontal wall moderately to markedly convex, smooth, uniformly perforated with small pores over entire surface, except for peristome; marginal zooids with an imperforate zone along each lateral margin. Orifice ( Figure 31A ) semicircular or rounded-quadrate in immature zooids, irregularly semicircular to rounded-quadrate in ovicellate zooids, 0.18–0.25 mm long (0.21¡ 0.02 mm), 0.19–0.25 mm wide (0.22¡ 0.02 mm), without oral spines, lyrula, or condyles. Peristome raised, continuous; cormidial, formed distally by raised, proximal wall of distal zooid, proximally by thick, raised, arcuate rim with a sharp median tooth ( Figure 31B, C ) and distolateral prominences. Avicularia and ovicells not seen in immature intertidal material. Interzooidal communications via multiporous septula. Ancestrula not observed.

In an ovicellate colony collected subtidally, zooids 0.67–1.10 mm long (0.87¡ 0.13 mm), 0.45–0.63 mm wide (0.52¡ 0.06 mm); orifice 0.21–0.27 mm long (0.23¡ 0.02 mm), 0.22– 0.31 mm wide (0.27¡ 0.03 mm); in ovicellate zooids, proximal peristomial rim overlaps proximolateral lappets of ovicell; sides of peristome finely granulated externally; median suboral tooth prominent, thin and hollow, or stout and blunt. Ovicells ( Figure 31C, D ) hyperstomial, globose, overlying frontal wall of distal zooid; broad, 0.27–0.35 mm long (0.32¡ 0.02 mm), 0.40–0.45 mm wide (0.43¡ 0.02 mm); granulated, uniformly perforated with many small pores; with large, oblong or slit-like basal openings in frontal wall of distal zooid, flanking ovicell on each side proximolaterally. Similar openings often occur at proximolateral edge of peristome of maternal zooid.

Remarks

Despite the apparent absence of lateral oral avicularia in our material, other characters confirm the identification of Cheilopora sincera . These characters include the convex, uniformly perforated frontal wall; cormidial secondary orifice with a well-developed median suboral tooth; and narrow slits at the base of the ovicell proximolaterally. In the absence of avicularia and the rounded-quadrangular outline of the secondary orifice, especially in mature zooids, Akkeshi specimens resemble Cheilopora inermis ( Busk, 1880) , previously recorded on the Pacific side of Hokkaido near Shirikishinai ( Mawatari and Mawatari 1981b). However, the frontal shield of C. inermis is always flat (see Kluge 1962, p 563, Figure 398), whereas that of C. sincera is convex, especially in ovicellate zooids; the proximal margin of the peristome is only gently convex in C. inermis , whereas in C. sincera the median suboral tooth is usually prominent.

Kluge (1952) described a new variety, C. sincera orientalis , based on material collected from the Chukchi Sea near Bering Strait. Subsequently, he reported the same form from Avacha Inlet, eastern Kamchatka, elevated to the rank of species as C. orientalis ( Kluge 1961) . Kluge’s primary justifications for elevating that taxon to species rank were the form of the suboral tooth (a wide, inflated process instead of a sharp tooth) and the occurrence of bilaminar colony form. However, Androsova (1958) described and illustrated the form and size of the suboral process in C. sincera as a significantly variable character that can be sharp, blunt, straight, cone-like, long or short, wide or narrow, or sometimes forked or entirely absent. Furthermore, colonies of C. sincera from the Ust’ Khayryuzovo area, western Kamchatka shelf, Sea of Okhotsk, can be quite variable in form (A. V. Grischenko, unpublished data). Some colonies encrusting the internal concave surface of dead shells of Chlamys sp. bivalves can be loosely attached with elevated margins, or even produce small, bilamellar frills and folds. Hence, C. orientalis falls within the range of variation of C. sincera , and we here consider it as a junior synonym of C. sincera .

Distribution

This is a circumpolar, Arctic-Boreal species; Kluge (1962, 1975) and Gontar and Denisenko (1989) provide detailed records for the Arctic. In the northwestern Pacific, C. sincera has been reported from eastern Kamchatka, the southern Kuril Islands, western and southern Sakhalin Island, the Shantar Archipelago ( Kluge 1961), and Primorye ( Androsova 1958); Akkeshi Bay is the southernmost known locality on the Asian side. Osburn (1952) expressed the opinion that C. praelucida (Hincks) , described from British Columbia, is likely synonymous with C. sincera (Smitt) , but he hesitated to make a formal synonymy without examining type material. O’Donoghue and O’Donoghue (1926) also reported C. praelucida from British Columbia.

Figures

Figure 6. Conopeum nakanosum n. sp. (A, F) NHM 2006.2.27.26; (B, D) NHM 2006.2.27.27; (C, E) NHM 2006.2.27.25; (G, H) NHM 2006.2.27.28. (A) Colony margin with differentiating zooids, bleached; (B) zooids with developing angular cone-shaped kenozooids, bleached; (C) mature zooids with erect and curved spines, unbleached; (D) group of mature zooids with granulated cryptocyst, bleached; (E) distally facing triangular avicularia replacing kenozooids, unbleached; (F) distal view of kenozooids, bleached; (G) lateral view of zooids showing multiporous septula, bleached; (H) interior of distal zooidal wall showing developing angular kenozooids and also multiporous septula, bleached. Scale bars: 0.5 mm (A, G); 1 mm (B–D); 0.2 mm (E, F, H).

Figure 12. Cauloramphus niger n. sp. (A–E) NHM 2006.2.27.16; (F) NHM 2006.2.27.17. (A) Developing zooids at colony margin, unbleached; (B) general view of group of zooids with immersed vestigial ovicells, unbleached; (C) zooids from colony periphery, showing numerous avicularia, unbleached; (D) close up of zooids with avicularia, unbleached; (E) autozooids with immersed ovicells and bases of spines, bleached; (F) ancestrula and periancestrular zooids, bleached. Scale bars: 0.5 mm.

Figure 13. Cauloramphus spinifer (Johnston, 1832). (A) NHM 2006.2.27.38; (B) NHM 2006.2.27.41; (C) NHM 2006.2.27.18; (D) NHM 2006.2.27.17. (A) Group of autozooids, unbleached; (B) distal half of zooid, showing avicularia, unbleached; (C) autozooids, bleached; (D) ancestrula and periancestrular zooids, bleached. Scale bars: 0.5 mm (A, C, D); 0.1 mm (B).

Figure 14. Tegella aquilirostris (O’Donoghue and O’Donoghue, 1923). HNM 2006.2.27.42. (A) Developing zooids near colony margin, bleached; (B) immature zooids with large frontal avicularia, bleached; (C) zooids with developing and completed ovicells, bleached; (D) mature zooids, showing ovicells with associated frontal avicularia, and also straight and curved spines, bleached. Scale bars: 0.5 mm.

Figure 31. Cheilopora sincera (Smitt, 1868). (A, B) NHM 2006.2.27.77; (C, D) NHM 2006.2.27.78. (A) Zooids differentiating at colony margin; (B) immature zooids; (C, D) mature zooids with ovicells. Scale bars: 0.5 mm (A, B, D); 1 mm (C).