Tegella horrida (Hincks, 1880)

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 : 3708-3711

Tegella horrida (Hincks, 1880)

( Figure 5A–D )

Membranipora horrida Hincks 1880a, p 82 , Plate 10, Figure 6 .

Membranipora californiensis Waters 1898, p 681 , Plate 49, Figure 14.

Membranipora horrida: Robertson 1908, p 260 , Plate 14, Figures 3, 4 ; O’Donoghue and

O’Donoghue 1923, p 24.

Callopora horrida: O’Donoghue and O’Donoghue 1925, p 97 ; 1926, p 33; Osburn 1950, p 69, Plate 6, Figure 9 ; Androsova 1958, p 98, Figure 9 ; Mawatari and Mawatari 1980, p 42, Figure 9 .

Tegella robertsonae: Osburn 1950, p 81 , Plate 9, Figure 5 (in part).

Tegella aquilirostris: Dick and Ross 1986, p 89 (in part).

Tegella horrida: Dick and Ross 1988, p 45 , Plate 3D–G.

Description

Colony. Unilaminar, encrusting, sheet-like, tightly adhering to hard substrates; light tanbrown in colour; largest observed 1.5 cm across.

Zooids. Oval, rounded distally, widest proximally; 0.45–0.66 mm long (average 50.559 mm, n 515, 3) by 0.28–0.38 mm wide (average 50.321 mm, n 515, 3); distinct when young ( Figure 5A ), separated by a groove, with scattered infundibular pits (incipient kenozooids, connecting to pores) and occasional small lacunae between zooids. Lateral gymnocyst smooth and sloping in young zooids; proximal gymnocyst obscured by chamber of avicularium, ovicell of preceding zooid, or both. With age, groove filled by kenozooidal secondary calcification ( Figure 5B ), zooidal boundaries indistinct, with external interzooidal (kenozooidal/lacunar) openings remaining; all gymnocyst obscured by heavy, irregular, smooth or finely tuberculate secondary calcification. Cryptocyst steeply sloping, moderately wide proximally, narrow distally, covered with small, sharp conical tubercles. Opesia occupies about three-fifths of frontal length; 0.25–0.40 mm long (average 50.302 mm, n 515, 3) by 0.15–0.25 mm wide (average 50.188 mm, n 515, 3); oval or rounded-rectangular; well separated from surrounding opesiae. Basal wall completely calcified.

Spines ( Figure 5C ). Marginal zooids have four to seven (mode56) straight orificial spines, erect or distally angled, sometimes longer than zooids; most or all of these are lost with age and abrasion. Around mural rim proximal to orifice are three to six short, tapering, acuminate, slightly curved spines angled toward midline. Some spines have an uncalcified ring at the base.

Avicularia. Three types occur. Some zooids have one to three small frontal avicularia arising anywhere around proximal or lateral gymnocyst, rostrum short and raised at 45 °, mandible an equilateral triangle pointing toward zooidal margin. Most common type is a large frontal avicularium ( Figure 5A–C ) with chamber covering most or all of proximal gymnocyst, connecting to it by several pores, and overlapping ovicell of preceding zooid; rostrum moderately raised, often laterally curved, decurved, or both, extending to a greater or lesser extent around proximolateral margin of opesia; mandible elongate, tapering, acute, hooked at tip. With increased secondary calcification ( Figure 5B ), frontal surface of avicularium comes to lie flush with colony surface. The third type comprises intramural avicularia ( Figure 5D ) scattered sparsely throughout colony; these are regenerated from autozooids, the autozooidal opesia partly closed with a horizontal lamina from which arises a raised rostrum of varying size, pointing in any direction, with a spatulate or triangular mandible.

Ovicell. Raised, globose, 0.20–0.30 mm wide (average 50.255 mm, n 515, 3) by 0.14– 0.23 mm long (average 50.173 mm, n 515, 3); ectooecium thick, rough, with proximal margin thickened as a transverse ridge ( Figure 5A ). The two layers nearly meet proximally, the space between them becoming occluded by secondary calcification except for occasional minute pores. With age, ovicell becomes partly or completely immersed by secondary calcification ( Figure 5B, C ).

Ancestrula . Not observed.

Remarks

This aptly named species is robust; the surface is rough in appearance, often abraded or fouled. We have examined a specimen from the Natural History Museum (London) labelled ‘‘97.5.1.512, Membranipora horrida Hincks , California, Pt. of TYPE? material’’. Specimens from Ketchikan are clearly conspecific with this specimen. In the NHM specimen, zooids show the characteristic elongate, curved and decurved proximal avicularia, with some having the smaller type; heavy, rough, granulate secondary calcification with kenozooidal/lacunar openings between zooids; widely spaced opesiae; up to six orificial spines and two to four short, acuminate opesial spines, with some spines having an uncalcified base. The ovicells in the Californian specimen are smooth, with a slight transverse ridge; similar ovicells are evident in young zooids in our material .

Distribution

This is a boreal North Pacific species, reported from Pacific Grove, California ( Robertson 1908) to Kodiak in the western Gulf of Alaska ( Dick and Ross 1988); northern Honshu and Hokkaido Islands, Japan ( Mawatari and Mawatari 1980); and the Sea of Japan ( Androsova 1958).

Figures

Figure 4. (A–D) Cauloramphus tortilis n. sp.: (A) autozooids; unbleached; (B) autozooids, bleached; complete zooid at right is a brooding zooid, with a crescentic kenozooidal ooecium around distal margin; (C) young autozooids near colony margin, showing intermeshing spine bases; bleached; (D) colony margin, showing pore chambers; bleached. (E, F) Tegella aquilirostris (O’Donoghue and O’Donoghue): (E) ovicellate zooids; unbleached; (F) ovicellate zooids; bleached. Scale bars: 500 Mm.

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).

Figure 6. (A, B) Bugula pacifica Robertson: (A) general colony view; (B) autozooids and lateral avicularia. (C, D) Bugula pugeti Robertson: (C) general colony view; (D) autozooids and lateral avicularia; note smaller avicularium near branch point (near top, right of centre). (E, F) Dendrobeania lichenoides Robertson: (E) autozooids and one ovicellate zooid; (F) abfrontal surface of portion of colony, showing attachment radicles. All specimens unbleached. Scale bars: 2 mm (A, C); 400 Mm (B); 1 mm (D, F); 500 Mm (E).

Figure 9. Celleporella hyalina (L.) species complex, showing variation between two colonies encrusting a single mussel (Mytilus edulis) individual collected subtidally; (A, B) are from one colony, (C, D) are from the other; both specimens bleached. (A) Autozooids near colony margin; (B) autozooids in primary layer (large primary orifices), a frontally budded male zooid (small primary orifice, at left), and frontally budded ovicellate zooids; (C) autozooids near colony margin; (D) autozooids in primary layer (large primary orifices), frontally budded male zooids (small primary orifices), and frontally budded ovicellate zooids. Scale bars: 500 Mm.