Phidolopora elongata ( 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 : 1147-1150

Phidolopora elongata ( Smitt, 1868)

( Figure 41 )

Retepora cellulosa forma notopachys var. elongata Smitt 1868, p 36 , Plate 28, Figures 226–332. Retepora wallichiana: Hincks 1877, p 107, Plate 11, Figures 9–13 ; 1884, p 55.

Retepora elongata: Androsova 1958, p 117 , Figure 107; Kluge 1961, p 142; 1962, p 527, Figure 368.

Phidolopora elongata: Hansen 1962, p 45 ; Cuffey and Turner 1987, p 67; Kubanin 1997, p 125; Grischenko and Ivanyushina 2002, p 32, Text figure 2.

Phydolopora elongata [sic]: Gontar 1980, p 13; 1990, p 133; 1992, p 188; 1993, p 202; 1996, p 46; Gontar and Denisenko 1989, p 357; Grischenko 1997, p 188.

? Retepora pacifica Robertson 1908, p 310 , Plate 24, Figures 81–84.

? Retepora pacifica: O’Donoghue and O’Donoghue 1923, p 189 .

? Phidolopora pacifica: Canu and Bassler 1923, p 154 , Plate 39, Figures 1–7 ; O’Donoghue and O’Donoghue 1925, p 106; 1926, p 118; Osburn 1952, p 448, Plate 53, Figures 1 , 2 ; Soule et al. 1995, p 277, Plate 106A–E.

Material examined

ANC, 10 colony fragments (NHM 2006.2.27.107), three colony fragments (NHM 2006.2.27.108), two young colonies on rock (NHM 2006.2.27.109) Additional material: three specimens; holotype, SMNH-1316, Svalbard, Hinlopen Strait , Waigatsöarna .

Description

Colony ( Figure 41A ) erect, orange in colour when alive, consisting of fenestrate bilaminar sheets, complexly folded and fused into rigid three-dimensional meshwork, largest observed 11×8× 4.5 cm in dimensions, rising from rounded base attached to substratum by kenozooids. Branches range from three to 11 zooids wide between fenestrulae. All feeding zooids open on one surface of a sheet; opposite surface consists of kenozooids. Fenestrulae elongate-oval or irregularly rhombic in shape, 0.7–1.9 long by 0.3–0.9 mm wide. Zooids ( Figure 41C ) hexagonal, rhombic, or oval, 0.48–0.70 mm long (0.59¡ 0.07 mm), 0.24–0.38 mm wide (0.31¡ 0.04 mm). Newly budded zooids delineated by raised vertical walls; in older regions of colony, boundaries between zooids occluded by secondary calcification or represented by fine sutures. Frontal wall slightly convex to inflated in young zooids, markedly convex in mature zooids, finely granulated, imperforate except for two or three pores along each proximolateral margin. Primary orifice ( Figure 41D ) long-semicircular, with beaded rim, 0.10–0.13 mm long (0.11¡ 0.01 mm), 0.09–0.13 mm wide (0.11¡ 0.01 mm); proximal margin straight, with shallow but distinct U-shaped sinus flanked by condylar shelves bearing low, blunt condyles. With age, primary orifice submerged in peristome; secondary orifice with median pseudosinus. Two short, hollow, ephemeral oral spines with enlarged bases frequently present at distolateral edges of primary orifice in marginal zooids. Large frontal avicularium ( Figure 41C–E ), 0.14– 0.20 mm long, with raised, beak-shaped rostrum, occupies central part of frontal wall in many zooids; cross-bar complete, rostral opesia triangular to oval in shape; mandible longtriangular, with acute tip, directed proximally or proximolaterally; avicularian chamber broad, conical, very prominent in immature zooids, inflated in ovicellate zooids ( Figure 41D ) by general thickening of frontal wall owing to secondary calcification, coarsely granulated, with two or three small pores flanking its base. Single transversely orientated avicularium occupies proximal abfrontal axils of fenestrulae ( Figure 41B ), 0.15– 0.18 mm long, with short, equilaterally triangular mandible; one or two pairs of circular pores flank rostrum. Ovicell ( Figure 41F ) hyperstomial, spherical, smooth, often forming a hood overhanging orifice, 0.18–0.23 mm long (0.20¡ 0.01 mm), 0.20–0.25 mm wide (0.22¡ 0.01mm), with incompletely calcified ectooecium having fine concentric striae; proximal edge of ovicell often with slight median denticle. Ovicell rapidly immersed ( Figure 41E ) by secondary calcification from distal and lateral zooids covering most of its surface, with fine sutures delineating calcification from different zooids. Dorsal surface of colony ( Figure 41B ) shows outlines of kenozooids of irregular form and size, recognizable by sutures indicating raised vertical walls; kenozooids inflated, roughly granulated, with a few sparse circular pores on the surface; avicularia lacking dorsally except for those in axils of fenestrulae. Ancestrula and early astogeny not observed.

Remarks

Specimens from Akkeshi Bay are similar in many characters to the type specimen of P. elongata (SMNH-1316, many fragments) ( Figure 41G, H ). Both have rhombic zooids with a submerged, rounded primary orifice having a shallow median sinus and encircled by peristome bearing a proximal pseudosinus. Large frontal avicularia are similar in form and position; the ovicells have, on the proximal margin, a median denticle that is often incompletely closed. There are some differences; specimens from Akkeshi Bay have 3–11 zooids comprising branches between fenestrulae, the type of P. elongata three to seven. This may be ecophenotypic variation, as depth-dependent variation in branch width occurs in P. elongata from the Commander Islands region; colonies from depths of 1–25 m have twice the number of zooids per branch than those from depths of 65–165 m (A. V. Grischenko, unpublished data). Another is that the abfrontal avicularian mandibles are larger with a long-triangular mandible in the type of P. elongata , versus smaller, with an equilateral mandible in specimens from Akkeshi.

A congener, P. pacifica ( Robertson, 1908) , is known from the eastern Pacific, reported from Alaska, Puget Sound, and the coast of California ( Robertson 1908); British Columbia ( O’Donoghue and O’Donoghue 1923, 1925, 1926); and from the Santa Barbara Channel to Mexico and the Galapagos Islands ( Soule et al. 1995). Soule et al. (1995) illustrated this species for the first time using SEM. Phidolopora pacifica appears to be similar to P. elongata in the shape of the orifice and the ovicell with a median denticle, which was also illustrated in line drawings by Robertson (1908) and Osburn (1952). However, P. pacifica seems to form more pronounced lappets flanking the peristomial pseudosinus, and the abfrontal avicularium appears to differ somewhat in shape and orientation. Unfortunately, Robertson’s types of P. pacifica were mixed with other specimens, and neotypes will eventually have to be selected; in any case, we here consider this species as valid. Records of P. pacifica from Mexico and the Galapagos Islands ( Osburn 1952; Soule et al. 1995) need re-examination.

Many large, erect colonies of P. elongata were found growing in horizontal crevices in solid rock at the base of a cliff overhang at Aininkappu Cape; these were inhabited by a number of benthic organisms, including ascidians, sabellid and spirorbid polychaetes, sponges, crustaceans, sipunculids, holothurians, nemerteans, and ophiuroids. A similar hermatypic growth form of this species, supporting a rich associated fauna, occurs below cliffs in the Commander Islands ( Grischenko and Ivanyushina 2002).

Distribution

Phidolopora elongata is considered a circumpolar Arctic-Boreal species; Kluge (1962, 1975) and Gontar and Denisenko (1989) gave many distributional records. In the northern Pacific, it has been previously reported from the Bering Sea near the Commander Islands ( Kluge 1961; Grischenko 1997; Grischenko and Ivanyushina 2002), along the Kuril Islands ( Gontar 1980, 1993), and in Tatar Strait in the northern Sea of Japan ( Kluge 1961). Akkeshi Bay is the southernmost known locality for this species in the western North Pacific.

Figures

Figure 1. Map of Akkeshi Bay showing the 10 sampling stations (filled squares); 5, 10, and 20 m depth contours are indicated. Inset shows the location of Akkeshi Bay on Hokkaido Island, northern Japan.

Figure 2. Dendrogram (below) showing similarity of sampling localities based on species presence/absence, and a map (above) showing the geographical distribution of three groups of sampling localities (circled) that are less than 70% similar in species composition between groups.

Figure 3. Electra korobokkura Nikulina, 2006. (A–C) NHM 2006.2.27.1; (D) NHM 2006.2.27.2. (A) Colony fragment with uniserial branches; (B) colony fragment with anastomosing, multiserial branches; (C) zooids without spinous processes; (D) zooids with spinous processes. All unbleached. Scale bars: 2 mm (A, B); 1 mm (C); 0.5 mm (D).

Figure 4. Electra arctica Borg, 1931. ZIRAS 36/50535. Colony on rock collected by A. V. Grischenko, 12 September 1992, Sea of Okhotsk, western Kamchatka shelf (57°36.039N, 156°9.009E), depth 78–81 m. (A) Portion of colony showing anastomosing, narrowly multiserial branches; (B) autozooids and kenozooids; (C) enlargement of autozooids and kenozooids; (D) autozooids with operculum in place and kenozooids with nearly completely closed aperture. Specimen lightly bleached. Scale bars: 2 mm (A); 1 mm (B); 0.5 mm (C, D).

Figure 5. Electra asiatica n. sp. (A, G) NHM 2006.2.27.19; (B) NHM 2006.2.27.20; (C, D) NHM 2006.2.27.21; (E, F) NHM 2006.2.27.24. Colony from Ptichiy Island, Sea of Okhotsk (H). (A, B) Colonies radiating in coherent, fan-shaped lobes from the point of origin, unbleached; (C) colony margin with developing zooids, unbleached; (D) astogenetically mature zooids, unbleached; (E) astogenetically mature zooids, bleached; (F) astogenetically mature zooids with a small interzooidal kenozooid (lower right quadrant), bleached; (G) ancestrula and periancestrular zooids; enlargement of ancestrular area seen in panel (A), unbleached; (H) astogenetically mature zooids, bleached. Scale bars: 2 mm (A, B); 0.5 mm (C–H).

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 7. Callopora craticula (Alder, 1856). NHM 2006.2.27.29. (A) General view of colony fragment, unbleached; (B) immature zooids near colony margin, unbleached; (C) mature zooids showing ovicells and associated avicularia, unbleached; (D) group of immature zooids and vicarious avicularium on right, unbleached. Scale bars: 0.5 mm (A); 0.2 mm (B–D).

Figure 9. Cauloramphus cryptoarmatus n. sp. (A, C, E) NHM 2006.2.27.14; (B, F) NHM 2006.2.27.31; (D) NHM 2006.2.27.13. (A) Colony margin with developing zooids, unbleached; (B) zooids at colony margin in interaction with Cribrilina annulata, showing numerous additional avicularia developing along vertical walls from pore chambers, bleached; (C) autozooids, unbleached; (D) autozooids, showing strongly developed granulated cryptocyst, bleached; (E) two zooids showing details of avicularia and spines, unbleached; (F) ancestrula surrounded by periancestrular zooids, bleached. Scale bars: 0.5 mm (A–D, F); 0.4 mm (E).

Figure 10. Cauloramphus magnus Dick and Ross, 1988. (A, C, D) NHM 2006.2.27.33–34; (B) NHM 2006.2.27.54; (E) NHM 2006.2.27.35; (F) NHM 2006.2.27.32. (A) Colony margin with developing zooids, unbleached; (B) same, bleached; (C) autozooids, unbleached; (D) close up of autozooids showing details of avicularia and spines, unbleached; (E) autozooids, bleached; (F) ancestrula and periancestrular zooids, bleached. Scale bars: 0.5 mm (A–C, E, F); 0.4 mm (D).

Figure 11. Cauloramphus multispinosus n. sp. (A) NHM 2006.2.27.36; (B, C) NHM 2006.2.27.38; (D, E) NHM 2006.2.27.37; (F) NHM 2006.2.27.40. (A) Colony margin with developing zooids, unbleached; (B) group of autozooids, unbleached; (C) close up of zooids showing details of distal erect spines and thin proximal spines strongly curved and arched over opesia, unbleached; (D) autozooids with variable form of proximal gymnocyst, bleached; (E) close up of zooids, unbleached; (F) ancestrula surrounded by periancestrular zooids, bleached. Scale bars: 0.5 mm.

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 41. Phidolopora elongata (Smitt, 1868). (A, F) NHM 2006.2.27.108; (B–E) NHM 2006.2.27.107; (G, H) SMNH-1316. (A) General view of colony fragment; (B) dorsal surface of colony, showing kenozooids and avicularia in abfrontal axils of fenestrulae; (C) immature zooids; (D) zooids with developing ovicells; (E) mature zooids; (F) close up of ovicells, showing details of denticles in middle of proximal margin; (G) mature zooids with ovicells possessing peculiar sharp denticle; (H) dorsal colony surface with kenozooids and avicularia in abfrontal axils of fenestrulae. Scale bars: 2 mm (A); 0.5 mm (B–E, G, H); 0.2 mm (F).