Porella donoghueorum, Dick & Grischenko & Mawatari, 2005

Dick, Matthew H., Grischenko, Andrei V. & Mawatari, Shunsuke F., 2005, Intertidal Bryozoa (Cheilostomata) of Ketchikan, Alaska, Journal of Natural History 39 (43), pp. 3687-3784 : 3735-3738

Porella donoghueorum , new species

( Figure 12C–H)

Porella columbiana: Osburn 1952, p 398 , Plate 46, Figures 7 , 8 ; Dick and Ross 1988,

p 64, Plate 5B, C; Soule et al. 1995, p 253, Plate 95; Grischenko 1997, p 180.

not Porella columbiana O’Donoghue and O’Donoghue 1923, p 41 , Plate 3, Figure 28;

1926 (as Smittina columbiana ), p 69.

Diagnosis

Zooids small to moderate in size; frontal wall smooth, with four to five conspicuous areolae along each lateral margin, some becoming occluded with age; marginal zooids with four ephemeral distal spines; rostrum of suboral avicularium elliptical, mandible semicircular; avicularian chamber with two to three conspicuous frontal pores; marginal frontal avicularia variably present; ovicell globose when young, immersed with age.

Type material

Holotype: ETN, unbleached and uncoated ( YPM 35845) . Paratype 1: KV, specimen KE- 122 bleached and coated for SEM ( YPM 35846) . Paratype 2: KV, specimen KE-2 bleached and coated for SEM ( YPM 35847) . Paratype 3: KV, specimen KE-18 bleached and coated for SEM ( YPM 35848) . Paratype 4: KV, specimen KE-27 bleached and coated for SEM ( NHM 2005.7.11.6) . Paratype 5: ETN, unbleached and uncoated ( NHM 2005.7.11.7) . Paratype 6: HP, unbleached and uncoated ( YPM 35849) . Paratype 7: ETN, unbleached and uncoated ( ZIRAS 1 /50531) .

Etymology

The species is named in honour of Charles and Elsie O’Donoghue, who contributed much to the knowledge of bryozoans along the Pacific coast of North America.

Description

Colony. Unilaminar, encrusting, white, glistening, forming circular to irregular patches on hard substrates; largest observed 1.5 cm across.

Zooids. Roughly hexagonal, barrel-shaped, or oval; translucent when young, opaque with age; marginal zooids distinct ( Figure 12C), separated by a shallow to deep groove flanked by areolar pores; small, 0.28–0.45 mm long (average 50.359 mm, n 540, 4) by 0.18– 0.33 mm wide (average 50.240 mm, n 540, 4).

Frontal wall. Inflated, irregular and convex in young zooids, with four to five large, irregularly shaped areolae along each lateral margin proximal to level of orifice, sometimes with slight marginal ribs between them; wall rapidly thickened by secondary calcification, becoming smoother and flatter in later stages ( Figure 12D); areolae diminished in size, with some of them occluded, but still conspicuous.

Orifice. Primary orifice ( Figure 12E) more than semicircular, with sides turning inward toward proximal margin; broader than long, 0.06–0.09 mm long (average 50.078 mm, n 540, 4) by 0.09–0.15 mm wide (average 50.108 mm, n 540, 4); corners rounded; lyrula low, broad, often so reduced it constitutes little more than a convexity; condyles small, rounded. Peristome of young zooids consists of sharp, raised, curved flanges lateral to the orifice, meeting a raised lip or the ovicell margin distally; with age, primary orifice lies deep in peristome. Secondary orifice irregularly oval, interrupted by avicularian rostrum near top of peristome.

Avicularia. Each zooid bears a suboral avicularium; rostrum circular or shortelliptical, tilted in proximal direction at about 45 ° to colony surface; bisected by a hinge bar; mandible semicircular, pointing proximally. Avicularian chamber broader than long; rectangular or crescentic, developing from an areolar pore on each side; occupying one-third to one-half the length of frontal wall; in later stages completely immersed by secondary calcification. Chamber bears usually two, sometimes three, frontal pores resulting from incomplete closure of the chamber as it forms ( Figure 12C). In addition, some zooids have one to three marginal frontal avicularia ( Figure 12F), budded from any of the areolae along the zooidal margin; chamber raised, irregular in size and shape, with one or two pores; rostrum and mandible similar in shape to those of suboral avicularium. Frontal avicularia occur sporadically; some colonies lack them altogether, and when present they occur on a few scattered zooids, or in small patches of the colony.

Spines. Marginal zooids have four long, ephemeral distal spines ( Figure 12C, E), the bases of which can sometimes be seen in the peristome of older zooids.

Ovicell ( Figure 12C, D, F). Globose and distinct in young zooids, overlying the frontal wall of the next distal zooid; broader than long, 0.11–0.18 mm long (average 50.136 mm, n 540, 4) by 0.10–24 mm wide (average 50.185 mm, n 540, 4); smooth, imperforate, the proximal margin upturned as a narrow lip; immersed with age, the top flush with the colony surface.

Ancestrula ( Figure 12G, H). Orifice with straight proximal margin, surrounded by eight spines; with a complement of five periancestrular zooids (one distal, two lateral, two proximolateral).

Remarks

O’Donoghue and O’Donoghue (1923) described Porella columbiana , a species that they noted is similar in some respects to P. major Hincks, 1884 . The original description of neither of these species mentions distal spines on marginal zooids, or pores in the chamber of the suboral avicularium. Osburn (1952) erroneously described and illustrated a different species as P. columbiana , characterized by having two to four distal spines and a suboral avicularian chamber with ‘‘about three small areolar pores’’. The areolae along the zooidal margin in Osburn’s (1952, Plate 46, Figure 7 , 8 ) species are clearly fewer than illustrated by O’Donoghue and O’Donoghue (1923, Plate 3, Figure 28) for P. columbiana . Subsequent authors ( Dick and Ross 1988; Soule et al. 1995) continued Osburn’s (1952) mistaken concept of P. columbiana .

Soule et al. (1995) declared a lectotype (NHM 1964.1.2.15) for P. columbiana O’Donoghue and O’Donoghue , which we have examined. The box labelled ‘‘ Lectotype, Pacific coast of N. America, O’Donoghue Collection’’ contains three colonies on separate bivalve shell fragments, all of which are clearly conspecific with one another and with two other colonies in a wooden depression slide labelled ‘‘ Porella columbiana O’D and O’D, Pac. Coast N. Amer. (Brit. Col.), part 1964.1.2.15)’’, which we consider as paralectotypes. SEM images ( Figure 13A–D ) of one of the colonies from the depression slide show that P. columbiana is clearly allied with P. major and P. acutirostris (see Remarks for P. acutirostris herein), and not conspecific with what Osburn (1952) and subsequent authors ( Dick and Ross 1988; Soule et al. 1995) treated as P. columbiana . Osburn’s species requires a new name, which we have given as P. donoghueorum .

Osburn (1952) and Soule et al. (1995) indicated larger zooids for populations of this species from British Columbia to southern California, as compared to populations from Kodiak ( Dick and Ross, 1988) and Ketchikan, Alaska. Furthermore, both Osburn (1952) and Soule et al. (1995) specifically noted the absence of frontal avicularia, which we observed in some of the Ketchikan specimens. Dick and Ross (1988) likewise did not find them in Kodiak specimens. The Alaskan material agrees so well in other characters with material from farther south that we suspect the size difference may reflect a latitudinal cline. As for the frontal avicularia, these were not present in every colony found at Ketchikan, and were sparse or patchily distributed when they did occur, which might explain why previous authors missed them. Thus, we consider P. donoghueorum a single species from the Gulf of Alaska to southern California.

Distribution

This is a boreal Pacific species, known in the eastern Pacific from Kodiak, Alaska ( Dick and Ross 1988) (as P. columbiana ) southward to Redondo Beach and Santa Monica, California ( Osburn 1952) (as P. columbiana ), and on the Asian side from the Commander Islands ( Grischenko 1997) (as P. columbiana ). Osburn’s (1952) record of this or a similar species (as P. columbiana ) from the Galapagos Islands needs to be re-examined.

Figures

Figure 7. (A, B) Cribrilina annulata (Fabricius): (A) autozooids and frontally budded dwarf ovicellate zooids; bleached; (B) autozooids (lower right), ovicellate zooids in primary layer (lower centre and left), and frontally budded dwarf ovicellate zooids (top); bleached. (C–F) Cribrilina corbicula (O’Donoghue and O’Donoghue): (C) astogenetically young autozooids; unbleached; (D) ovicellate zooids in primary layer and frontally budded dwarf ovicellate zooids; bleached; (E) ovicellate zooids in primary layer and newly forming dwarf ovicellate zooids with membranous front only (upper left of centre) or with incomplete costae (lower right and centre); note compressed, subspatulate suboral costae; unbleached; (F) ancestrula and surrounding zooids; unbleached. Scale bars: 500 Mm (A–E); 1 mm (F).

Figure 8. (A–D) Puellina caesia n. sp.: (A) group of autozooids; bleached; (B) group of ovicellate zooids; bleached; (C) colony margin showing several stages of ovicell formation; bleached; (D) enlargement showing setiform papillae proximolateral to orifice; unbleached. Scale bars: 400 Mm (A); 500 Mm (B, C); 200 Mm (D).

Figure 13. Porella columbiana O’Donoghue and O’Donoghue, paralectotype, BMNH 1964.1.2.15; bleached: (A) group of autozooids; (B) zooids near colony margin showing stages in formation of suboral avicularian chamber; (C) group of ovicellate zooids; (D) enlargement of autozooidal orifice showing condyles and weak lyrula. Scale bars: 500 Mm (A–C); 200 Mm (D).