Integripelta, 2002

Gordon, Dennis P., Mawatari, Shunsuke F. & Kajihara, Hiroshi, 2002, New taxa of Japanese and New Zealand Eurystomellidae (Phylum Bryozoa) and their phylogenetic relationships, Zoological Journal of the Linnean Society 136 (2), pp. 199-216 : 205

INTEGRIPELTA NOVELLA SP. NOV.

( FIG. 2A, B )

Material examined

Holotype: ZIHU 02034 , from 43°3¢N, 140°35¢E, 0 m, the rocky tidal flat of Kamekawa, Kikonai-cho, Shirabeshi Prefecture , Hokkaido.

Paratype: ZIHU 02035 , same locality as holotype .

Description

Colony encrusting, multiserial, unilaminar. Autozooids contiguous, quincuncially arranged, 0.39– 0.75 mm long (0.52 ± 0.08 mm), 0.33–0.45 mm wide (0.39 ± 0.03 mm). Gymnocystal frontal shield smoothsurfaced, somewhat convex, no umbo or carina, lacking fenestrae. Orifice somewhat hat-shaped, the anter high-arched with the proximal embayments rounded, the proximal rim of the poster gently and evenly concave or straight; the lateral excavations of the gymnocyst very well developed, occurring adjacent to the embayments and extending proximally, on one or both sides, for a considerable distance, often equivalent to half the zooid length. Orifice of maternal zooids dimorphic, though not always obviously so (0.26–0.31 mm wide at the proximal margin compared to that of autozooids 3/4 0.20–0.26 mm); distal kenozooidal chamber forming a somewhat triangular cap, with a transverse to circular sloping shelf of interior wall and a small circular foramen. No basal porechambers, interzooidal communications comprising a row of uniporous septula along each lateral wall. Ancestrula not seen.

Etymology

From novellus (L.), diminutive of novus, new.

Remarks

Integripelta novella closely resembles the type species, I. bilabiata , which, however, is much larger in size. According to Soule et al. (1995), autozooids of I. bilabiata are 0.60–0.65 mm long and 0.50–0.55 mm wide with an orifice width of 0.30–0.32 mm (hence the widths of zooids and orifices do not even overlap in the two species). Additionally, the shallow gymnocystal excavations in I. novella are proportionately very much longer whereas the kenozooidal foramen is tiny and surrounded by a broader area of interior wall.

Apart from those sources already mentioned, Integripelta bilabiata has been recorded or described by Hincks (1882, 1884), Robertson (1908), O’Donoghue & O’Donoghue (1925, 1926), Osburn (1952), and Banta (1973). Soule et al. (1995) gave its range as Nootka Island, Alaska, through British Columbia to southern California and to Navidad Head, Mexico, at depths of 168–237 m, but it has also been recorded intertidally ( McBeth, 1971). It is also known from the Pleistocene of southern California ( Soule & Duff, 1957). Robertson (1908) described the operculum of I. bilabiata in some detail — it appeared to be two-layered and, together with the distal rim of the orifice, the whole structure appeared to be superficially bilabiate. Judging from observations on I. sextaria (below) the ‘bilabiate’ appearance obtains in dried material, in which the distal vestibular wall may be accentuated if slightly protruding. While the operculum proper may be thin, a descending cuticular rim around its periphery can give the appearance of thickness. The orificial structure of I. japonica (below) is not known.

Distribution

Known with certainty only from the intertidal zone at the type locality in Hokkaido.

Figures

Figure 2. A, B. Integripelta novella sp. nov. Hokkaido, intertidal. A, autozooids and two maternal zooids, the kenozooid distal to the one at left lacking a foramen, ¥89. B, maternal zooid with distal foraminate kenozooid, ¥121. C, D, Integripelta japonica sp. nov. Mi-shimi, Honshu. C, autozooids and maternal zooids, ¥53. D, maternal orifice and kenozooid, ¥211. E, F, Integripelta sextaria sp. nov. NZOI Stn Z9700. E, autozooids and maternal zooids, ¥48. F, autozooidal orifice, ¥181.