Microporella setiformis O’Donoghue and O’Donoghue, 1923

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 : 3752-3753

Microporella setiformis O’Donoghue and O’Donoghue, 1923

( Figure 18C, D )

Microporella setiformis O’Donoghue and O’Donoghue 1923, p 32 , Plate 3, Figure 21;

1926, p 65, Plate 5, Figure 44.

Microporella setiformis: Osburn 1952, p 385 , Plate 44, Figure 8 ; Soule et al. 1995, p 150,

Plate 53.

Description

Colony. Unilaminar, encrusting; white, covered with shiny ectocyst.

Zooids. Irregularly hexagonal, distinct, separated by a deep groove; variable in size and shape, markedly elongate or nearly as wide as long; 0.55–0.80 mm long (average 50.666 mm, n 511, 1) by 0.40–0.58 mm wide (average 50.492 mm, n 511, 1).

Frontal wall. Convex, rising sharply around margin, flatter on top, even, without umbo, finely granulated; with 10–14 areolar pores along each lateral margin and smaller, slightly infundibular pores over entire surface.

Orifice. As wide as or slightly wider than long, 0.10–0.13 mm long (average 50.122 mm, n 511, 1) by 0.13–0.15 mm wide (average 50.138 mm, n 511, 1); sides recurve slightly toward proximal margin, which is shallowly concave between small, shelf-like condyles; peristome a low, smooth, rim around curvature of orifice, with a straight hinge shelf along proximal margin.

Ascopore. More-or-less circular, often with a small denticle projecting from the distal margin; surrounded by a flat, smooth collar abutting proximal rim of orifice.

Spines. No spines or spine scars evident in our specimens.

Avicularia. Small, oval; near zooidal margin lateral to ascopore on one or both sides, pointing distolaterally, with a setose mandible roughly three times as long as rostrum.

Ovicell. Not observed.

Ancestrula . Not observed.

Remarks

Microporella setiformis was rare at Ketchikan; we collected two colonies at Higgins Point. Although we observed no spines or spine scars, both Osburn (1952) and O’Donoghue and O’Donoghue (1926) reported this species to have five evanescent oral spines on marginal zooids.

Distribution

Microporella setiformis is a boreal species endemic to the north-eastern Pacific. Osburn (1952) summarized records from numerous localities in British Columbia, Puget Sound, and as far southward as the Channel Islands in Southern California. Ketchikan is the northernmost extent of the known range .

Figures

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 18. (A, B) Cryptosula zavjalovensis Kubanin: (A) group of autozooids with broad-type orifice; (B) group of autozooids, with broader and narrower orifices. (C, D) Microporella setiformis O’Donoghue and O’Donoghue: (C) group of autozooids; (D) enlargement of orifice, ascopore, and marginal avicularium. All specimens bleached. Scale bars: 500 Mm (A–C); 200 Mm (D).