Cauloramphus multiavicularia, 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 : 3701-3704

Cauloramphus multiavicularia , new species

( Figure 3A–F)

Membranipora spinifera: O’Donoghue and O’Donoghue 1923, p 26 (in part?).

Cauloramphus spinifer: O’Donoghue and O’Donoghue 1926, p 39 (in part?).

Cauloramphus pseudospinifer: Dick and Ross 1988, p 37 , Plates 2A, H, 13C.

Diagnosis

Up to seven stout orificial spines, erect or nearly so, well differentiated from tight basket of thinner, more acuminate spines proximal to orifice that angle over opesia, variably meeting in midline. Gymnocyst smooth; cryptocyst sloping, with coarse, rounded tubercles. Basal wall uncalcified in centre. Up to five avicularia per zooid emerging from middle of zooid on either side and around distal margin. Avicularia thin, clavate, pedunculate, often directed nearly horizontally at colony margin.

Type material

Holotype: ETN, unbleached and uncoated ( YPM 35832) . Paratype 1: ETN, unbleached and uncoated ( YPM 35833) . Paratype 2: ETN, unbleached and uncoated (NHM 2005.7.11.1). Paratype 3: KV, specimen KE-8 bleached and coated for SEM ( YPM 35834) . Paratype 4: KV, specimen KE-59 unbleached and coated for SEM ( ZIRAS 1 /50527) . Paratype 5: SC, specimen KE-61, aberrant ecophenotype, lightly bleached and coated for SEM ( YPM 35835) . Paratype 6: KV, specimen KE-31 bleached and coated for SEM ( ZIRAS 2 /50527) .

Etymology

The species name derives from Latin meaning ‘‘many avicularia’’.

Description

Colony. Unilaminar, encrusting, light tan-brown in colour, forming irregular to circular patches tightly adhering to hard substrates; largest observed 2 cm across.

Zooids. Irregularly oval to rounded-hexagonal, variable in size and shape with irregularities in substrate, 0.50–0.87 mm long (average 50.685 mm, n 515, 3) by 0.38–0.50 mm wide (average 50.412 mm, n 515, 3); closely set, but separated by a distinct groove; proximally quadrate or tapering to a median or two lateral lobes between adjacent zooids; basal wall with an irregular marginal shelf but uncalcified in centre ( Figure 3B). Openings to pore chambers ( Figure 3D) unusually small for the genus (compare Figure 3D with Figures 2H and 4D ); seen from margin, the circular or irregularly oval openings lie at base of distolateral and distal walls, and are about one-third the height of the wall. Gymnocyst smooth; narrow or obscured if zooids crowded; generally evident proximally. Cryptocyst rounded, sloping inside mural rim; covered with coarse, rounded tubercles ( Figure 3B, D). Opesia elliptical to oval, 0.38–0.58 mm long (average 50.495 mm, n 515, 3) by 0.25– 0.33 mm wide (average 50.274 mm, n 515, 3).

Spines ( Figure 3A, C). Total 16–23 (mode518, n 515, 3), including five to seven stout, blunt, erect orificial spines (mode56, n 515, 3) and 11–17 (mode514, n 515, 3) slightly curved, acuminate opesial spines angled over proximal two-thirds of opesia, the tips usually meeting nearly horizontally at midline to form a tight basket.

Avicularia ( Figure 3A, C). Thin, clavate, 0.20–0.28 mm long (average 50.241 mm, n 516, 3); peduncle expanding gradually to a chamber about as thick as thickest spines; often laterally compressed. Avicularia originate from marginal gymnocyst anywhere around the distal margin anterior to the third pair of erect orificial spines, or from either side in the zone between the first and fourth pairs of angled opesial spines; the most avicularia observed on a single zooid was five. Avicularia angle away from zooid to a greater or lesser extent ( Figure 3C), sometimes orientated nearly horizontally on marginal zooids, the rostral side facing upward.

Ovicell. Embryos brooded inside the distal part of maternal zooid; ooecium exists as a small kenozooid budded by the maternal zooid and occupying the distal margin of the mural rim ( Figure 3B), evident as a raised, crescentic lip in brooding zooids.

Ancestrula . 0.38 mm long by 0.30 mm wide, with 12 spines ( Figure 3E); periancestrular zooids smaller than subsequent autozooids, but similar in form, often bearing avicularia.

Remarks

In Alaska, this species was previously found at Kodiak by Dick and Ross (1988), who identified it as C. pseudospinifer Androsova, 1958 . This determination was based largely on a specimen from the Sea of Japan, obtained from the Academy of Sciences in St Petersburg and labelled as C. pseudospinifera . After re-examination of that specimen by SEM and comparison with Ketchikan specimens, we believe the two are distinct species; hence, we here describe the Ketchikan material as a new species, C. multiavicularia .

Cauloramphus multiavicularia is similar to C. pseudospinifera ( Figure 3G, H) in most characters. In both, the smooth gymnocyst is reduced laterally and variably evident proximally; the sloping cryptocyst is covered with coarse, rounded tubercles; spines are similar in number (18–23 in C. pseudospinifera , 16–23 in C. multiavicularia at Ketchikan), form, and arrangement (e.g. compare Figure 3A with Figure 3G). Both species have the basal wall uncalcified in the centre. Zooid length is similar; C. pseudospinifera is 0.5–0.8 mm long ( Androsova 1958); C. multiavicularia is 0.60–0.80 mm long at Kodiak ( Dick and Ross 1988) and 0.50–0.87 mm long at Ketchikan. Both species can have at least two avicularia on the same side of the zooid.

The diagnostic difference between the two species lies in the shape and number of avicularia (compare Figure 3A and C with Figure 3G and H). Androsova (1958) noted for C. pseudospinifera that avicularia are rare, usually one or two per zooid when they occur; and similar in form to those of C. spinifera , with a short peduncle and a short, rather wide chamber ( Figure 3G, H). In C. multiavicularia , the avicularia have a long peduncle that expands gradually to a narrow chamber that is often scarcely, if at all, thicker in any direction than the thickest of the orificial spines ( Figure 3C). In Ketchikan specimens, avicularia are profuse and especially evident on marginal zooids ( Figure 3C), which may have up to five horizontally orientated avicularia per zooid scattered around the lateral and distal margins. In bleached specimens, most marginal zooids show one or more avicularium scars ( Figure 3D) around the distal end and one or more scars on each side laterally. Avicularia are less profuse in material from Kodiak ( Dick and Ross 1988), though their narrow, pedunculate form is the same as at Ketchikan.

At Settlers Cove, we found one colony ( Figure 3F) that appeared to represent yet another Cauloramphus species at Ketchikan. All spines are very thick, nearly straight, and blunt. However, zooid size, a sloping cryptocyst with coarse, rounded tubercles, and distal avicularium scars indicate that this specimen is an ecophenotypic variant of C. multiavicularia .

Distribution

C. multiavicularia is known only from the vicinities of Kodiak and Ketchikan, Alaska. However, O’Donoghue and O’Donoghue (1923, 1926) described specimens they identified as C. spinifera from British Columbia as having avicularia distributed both laterally and distally, with up to six present on some zooids, strongly suggesting that at least part of the material they examined was C. multiavicularia .

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.