Pacificincola perforata ( Okada and Mawatari, 1937 )

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 : 1122-1125

Pacificincola perforata ( Okada and Mawatari, 1937)

( Figure 30 ) Mucronella perforata Okada and Mawatari 1937, p 442 , Plate 1, Figure 8 , Text figure 4A–C. Hippoporina perforata: Huang et al. 1990, p 744 , Figure 8 , c. Pacificincola perforata: Liu and Liu 1999, p 340 , Text figure 1a–c, Plate 1, Figures 1–5 ; Liu et al. 2001, p 572, Plate 44, Figures 1 , 2 . Hippodiplosia insculpta: Kubanin 1975, p 123 , Figure 3b, c (not Schizoporella insculpta Hincks, 1882 ).

Material examined

KAI, colony on rock (NHM 2006.2.27.60), colony on rock (NHM 2006.2.27.75), young colony detached from bivalve shell (NHM 2006.2.27.76). Additional material: 201 specimens.

Description

Colony encrusting, unilaminar, coherent, forming delicate crusts of very irregular form with meandering margins, up to about 3 cm in maximum dimension, light yellow when alive. Zooids ( Figure 30A, B, E ) hexagonal, ovoid, or irregularly rectangular, widest in middle, 0.40–0.60 mm long (0.53¡ 0.06 mm), 0.25–0.43 mm wide (0.33¡ 0.05 mm), rounded distally, demarcated by a groove and fine suture line. All zooids of one type; non-fertile and fertile zooids similar in size and in size and form of orifice. Frontal wall convex, vitreous, texture smooth or granulated, uniformly perforated with circular pores, except for suboral area; with age, pores become infundibular and the frontal wall appears reticulate; proximal to orifice is a heterozooidal chamber ( Figure 30C ) appearing as a raised, crescentic arch or umbo, with a median distal cavity covered by membrane. Primary orifice ( Figure 30C ) roughly circular or broader than long, 0.10–0.14 mm long (0.12¡ 0.01 mm), 0.10– 0.15 mm wide (0.13¡ 0.01 mm); with a high, semicircular anter separated from narrower, shorter poster by a pair of small condyles pointing proximomedially; proximal orificial margin straight. Peristome low; orifice flanked laterally by low, sharp, curved peristomial flanges extending distally from umbo, connecting with proximal corners of ovicell or raised proximal margin of distal zooid, sometimes present as distinct lateral lappets. Ovicell ( Figure 30D, E ) globose, prominent, 0.19–0.25 mm long (0.22¡ 0.02 mm), 0.20–0.27 mm wide (0.23¡ 0.02 mm), recumbent on frontal wall of distal zooid and partially overhanging orifice; imperforate, with smooth or slightly nodular central area and short, finely tuberculate radiating ribs around periphery, with series of slit-like pores around distal margin. Spines and avicularia lacking. Zooids intercommunicate via multiporous septula. Ancestrula ( Figure 30F ) similar to later zooids but elongate-oval, 0.45 mm long, 0.23 mm wide, inflated frontal wall finely granulated and perforated with numerous pores; ancestrular orifice roughly circular, 0.10 mm long, 0.09 mm wide, with reduced peristomial rim and small suboral opening; ancestrula buds quartet of smaller zooids, two distolaterally and two laterally; surrounded by seven zooids.

Remarks

Pacificincola perforata ( Okada and Mawatari, 1937) was originally described from Onagawa Bay on the Pacific side of northern Honshu. It was subsequently reported (as Hippodiplosia insculpta ) from the Peter the Great Gulf ( Kubanin 1975) and (as Hippoporina perforata ) from the Hong Kong vicinity ( Huang et al. 1990). Liu and Liu (1999) used P. perforata from the coastal waters of China as the type species for the new genus Pacificincola and a new family, Pacificincolidae .

Pacificincola perforata most resembles its congener P. insculpta ( Hincks, 1882) in having a similar, crescentic proximal suboral arch with a central cavity covered by membrane, and prominent spherical ovicells with radiating ribs. However, P. perforata differs from the latter in the following characters: (1) non-fertile and fertile zooids of P. perforata are all of the same type, whereas they are dimorphic in P. insculpta ; (2) zooids of P. perforata are mostly distinctly hexagonal, widest in the middle, whereas zooids of P. insculpta are widest at the orifice, and tapering or truncate; (3) the lateral peristomial lobes, peculiar to P. perforata , are absent in P. insculpta , where the secondary orifice is a continuous rim; (4) the condyles are minute in P. perforata , but larger, prominent and shelf-like, in P. insculpta ; (5) ovicells of P. perforata have reduced peripheral ribbing, in contrast to the well-developed ribs on ovicells of P. insculpta ; and (6) the ancestrula of P. perforata is similar to later autozooids and buds four daughter zooids, whereas that of P. insculpta is tatiform and buds three daughter zooids (see Nielsen 1981, p 108, Figures 14 , 15 ); and (7) colonies of P. perforata are always encrusting and tightly attaching to the substrate, whereas those of P. insculpta are initially unilaminar but then rise in irregular, bilaminar lobes and frills.

Distribution

This species ranges from Akkeshi Bay on the Pacific side of Hokkaido and Peter the Great Gulf, Sea of Japan ( Kubanin 1975) southward to Onagawa Bay, Honshu ( Okada and Mawatari 1937), Hong Kong ( Huang et al. 1990), and China ( Liu and Liu 1999).

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 8. Callopora sarae n. sp. (A, E) NHM 2006.2.27.5; (B) NHM 2006.2.27.3; (C, D, F) NHM 2006.2.27.4. (A) Zooids at colony edge, unbleached; (B) immature zooids with spines, lateral and proximal avicularia, unbleached; (C) immature zooids, showing bases of spines and lateral avicularia, bleached; (D) two immature zooids showing bases of additional spines on outer distolateral gymnocyst, bleached; (E) mature zooids with ovicells and associated avicularia, unbleached; (F) mature zooids with heavily calcified ovicells, bleached. Scale bars: 0.5 mm (A–C, E, F); 0.4 mm (D).

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 15. Tegella arctica (d’Orbigny, 1851). (A, C) NHM 2006.2.27.44; (B) NHM 2006.2.27.46; (D) NHM 2006.2.27.43. (A) General view of group of autozooids, unbleached; (B) zooids from region near colony margin, bleached; (C) immature zooids with small paired angular and large frontal avicularia, unbleached; (D) mature zooids with ovicells and associated frontal avicularia, unbleached. Scale bars: 1 mm (A); 0.5 mm (B, C); 0.4 mm (D).

Figure 30. Pacificincola perforata (Okada and Mawatari, 1937). (A, D) NHM 2006.2.27.75; (B, C, F) NHM 2006.2.27.76; (E) NHM 2006.2.27.60. (A) Colony edge with differentiating zooids; (B) immature zooids; (C) orifice of immature zooid, showing minute sharp condyles and suboral umbo with central cavity; (D) zooids with developing ovicells; (E) two mature zooids with completed ovicells; (F) ancestrula and periancestrular zooids. Scale bars: 0.5 mm (A, B, D, E); 0.1 mm (C); 0.4 mm (F).