Hincksina Norman, 1903

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 : 3711-3712

Genus Hincksina Norman, 1903

Hincksina longiavicularia Gontar, 1982

( Figure 5E, F )

Hincksina longiaviculari a Gontar 1982, p 547, Plate 1, Figure 3a, b.

Hincksina longiaviculari a: Dick and Ross 1988, p 32, Plate 1E.

Hincksina sp. : Dick and Ross 1986, p 89.

Description

Colony. Unilaminar, encrusting, sheet-like, forming circular, bright golden-orange patches on hard substrates; largest observed 10 cm across. Tightly adhering, but sometimes with raised margin attached by radicles, each originating from the basal wall at the distal midline of a zooid, with a branched holdfast.

Zooids. Elongate, barrel-shaped, widest in middle, 0.40–0.55 mm long (average 50.462 mm, n 515, 3) by 0.19–0.25 mm wide (average 50.221 mm, n 515, 3); distal end of each zooid raised above proximal end of succeeding zooid, often with a sharp, raised lip distal to orifice. Cryptocyst lacking; opesia occupies entire frontal surface.

Spines ( Figure 5E, F ). Each autozooid surrounded by dense palisade of 10–17 coarse, tapering, acuminate, straight or slightly curved spines, including two pairs of nearly erect orificial spines and 6–13 opesial spines angled inward, tips meeting at midline.

Avicularia. Large, vicarious ( Figure 5E ), 0.30–0.45 mm long (average 50.370 mm, n 515, 3) by 0.14–0.18 mm wide (average 50.159 mm, n 515, 3); rostral walls smooth, the end overhanging succeeding zooid; mandible long-spatulate. Avicularia usually occur at a branch point where a zooid in series gives rise to two daughter zooids, one of which develops as an autozooid, the other as an avicularium. This arrangement is not obligatory; an avicularium occasionally replaces a zooid not at a branch point, and not every branch point has an avicularium.

Ovicell ( Figure 5F ). Globose, 0.10–0.18 mm long (average 50.126 mm, n 515, 3) by 0.13– 0.18 mm wide (average 50.155 mm, n 515, 3); endozooecial in cystid of succeeding zooid; endooecium covered by lateral flaps of ectooecium growing from each margin and fusing in midline; ovicell not closed by zooidal operculum, but rather by an extension of frontal membrane distal to operculum. In ovicellate zooids, distalmost pair of orificial spines often tilt medially, the tips meeting in the midline to form an arch protecting ovicell.

Ancestrula . One observed; oval, 0.35 mm long by 0.25 mm wide, with 10 (?12) short spines, including four erect orificial spines and six (?eight) thinner opesial spines angled inward; surrounded by seven zooids: one distal, two distolateral, two proximolateral, two proximal.

Distribution

The occurrence of this species at Ketchikan extends the known range in the north-eastern Pacific considerably southward from Kodiak and Prince William Sound ( Dick and Ross 1988). On the Asian side, H. longiavicularia has been reported from the Kurile Islands ( Gontar 1982) and Commander Islands ( Grischenko 1997).

Figures

Figure 5. (A–D) Tegella horrida (Hincks): (A) group of ovicellate zooids near colony margin, well separated with scattered lacunae between them; bleached; (B) group of heavily calcified ovicellate zooids, the avicularium proximal to opesia completely immersed; bleached; (C) group of ovicellate zooids; unbleached; (D) autozooid (left) and intramural reparative avicularium (right); bleached. (E, F) Hincksina longiavicularia Gontar: (E) group of autozooids and spatulate vicarious avicularia; unbleached; (F) several ovicellate zooids; unbleached. Scale bars: 500 Mm (A–C, E); 200 Mm (D, F).