Cauloramphus cryptoarmatus, Grischenko & Dick & Mawatari, 2007

Grischenko, Andrei V., Dick, Matthew H. & Mawatari, Shunsuke F., 2007, Diversity and taxonomy of intertidal Bryozoa (Cheilostomata) at Akkeshi Bay, Hokkaido, Japan, Journal of Natural History 41 (17 - 20), pp. 1047-1161 : 1074-1077

Cauloramphus cryptoarmatus new species

( Figure 9 )? Cauloramphus spiniferus [sic]: Liu et al. 2001, p 458, Plate 20, Figures 2–4 .

Diagnosis

Zooids closely appressed; gymnocyst negligible; cryptocyst strongly developed, widest proximally, entirely and uniformly coarsely granulate; 8–10 spines, generally short, not meeting in opesial midline, including two to four straight orificial and four to six thin, curved opesial spines; avicularia commonly paired, originating between orificial and opesial spines, approximately lateral to proximal orificial border, with short, thin pedicel abruptly expanding into curved chamber; non-pedunculate avicularia can arise from pore chambers at colony margin, sometimes in abundance.

Etymology

The species name is from the Greek kruptos (hidden) and Latin armatus (armed), referring to the occurrence of small marginal avicularia, which are unusual for the genus.

Material examined

Holotype: ANC, colony on rock (NHM 2006.2.27.14). Paratypes: ANC, colony on rock (NHM 2006.2.27.13); ANC, colony on rock (NHM 2006.2.27.31). Additional material: 80 specimens.

Description

Colony unilaminar, encrusting, coherent, irregularly circular in outline, up to 2.2 cm across; light yellow, greyish, or whitish when alive. Zooids ( Figure 9A–F ) very variable in form: oval, irregularly hexagonal, pyriform, tapering, or irregular; 0.52–0.73 mm long (0.60¡ 0.06 mm), 0.30–0.40 mm wide (0.35¡ 0.03 mm); closely appressed, separated by shallow groove with fine, undulating suture. Mural rim cryptocystal ( Figure 9B, D, E ); wide, rounded, tumid, entirely covered with uniform, coarse granules; relatively narrow and steep distally, widening laterally, widest proximally; opesiae well separated. Gymnocyst greatly reduced, negligible. Opesia ( Figure 9B, D, E ) irregularly oval, often with straight proximal margin, widest in middle or more proximally, 0.32–0.40 mm long (0.37¡ 0.02 mm), 0.17–0.27 mm wide (0.20¡ 0.02 mm), occupying 60–75% of zooidal length. Mural rim with 8–10 spines ( Figure 9C, E ), including three or four hollow, straight, vertically orientated orificial spines, arranged in a semicircle around distal curvature of orifice, that are slightly longer, thicker, and blunter than the rest; and four to six short, thin, acuminate spines curving over opesia. Pedunculate avicularia ( Figure 9E ) originate from distolateral gymnocyst between orificial and opesial spines, approximately in line with proximal edge of orifice; longer than distal spines, with comparatively short, thin peduncle abruptly expanding into curved chamber; orientated vertically or angling over opesia, with rostral side facing proximolaterally; mandible narrow, elongate-triangular; avicularia commonly paired, sometimes single; rarely zooids lack them altogether. Where colonies of C. cryptoarmatus encounter other bryozoan species, zooids at the colony margin can produce numerous (up to nine) small, closely set additional avicularia ( Figure 9B ), each developing from a pore chamber along the free distal and distolateral walls; these avicularia non-pedunculate, chamber slightly elevated; mandible triangular, with sharp tip. Embryos brooded endozooidally; fertile zooids have a small kenozooidal ooecium ( Figure 9D ) comprising the mural rim distal to the orifice. Six pore chambers in each lateral wall and two or three in distal wall. Ancestrula ( Figure 9F ) tatiform, oval, 0.28 mm long, 0.20 mm wide, with large, oval opesia, 0.19 mm long by 0.13 mm wide, with 12 short, hollow spines. Ancestrula ( Figure 9F ) buds triplet of small zooids distally and distolaterally; eventually surrounded by seven zooids.

Remarks

Cauloramphus cryptoarmatus resembles eastern-Pacific C. variegatus ( Hincks, 1881) and C. tortilis Dick et al., 2005 and Korean C. korensis Seo, 2001 in having closely appressed zooids with a broad, cryptocystal mural rim uniformly covered with coarse granules. However, in C. variegatus , the bases of the spines are yellowish brown to black in colour ( Dick and Ross 1988), and their number, shape, and arrangement are different: there are three pairs of blunt, cylindrical distal spines and two to six much finer, acuminate proximal spines curved over the opesia, with the tips often converging near the midline. Cauloramphus tortilis has more and longer spines (9–15 heavy, elongate spines, with strong bases conspicuous after bleaching), and the pedunculate avicularia are as long as the longest spines, with a peduncle that is twisted around the spine near which it originates. Cauloramphus korensis is similar in having a coarsely granulated cryptocyst widest proximally ( Seo 2001). However, C. korensis has dark spines that are brown or violet in colour, fewer total spines (five to nine) and fewer orificial spines (one to three), and the proximalmost opesial spines originating close to the edge of the opesia (see Seo 2001, Figure 1A ) rather than at the zooidal margin. Furthermore, the pedunculate avicularium of C. korensis is quite curved in the rostral direction, whereas that of C. cryptoarmatus is fusiform. Finally, the kenozooidal ooecium of C. korensis is larger and more conspicuous than that of C. cryptoarmatus . The non-pedunculate marginal avicularia observed in some colonies of C. cryptoarmatus have not been reported in the other species just mentioned.

Distribution

Cauloramphus cryptoarmatus is presently known only from Akkeshi Bay.

Figures

Figure 1. Map of Akkeshi Bay showing the 10 sampling stations (filled squares); 5, 10, and 20 m depth contours are indicated. Inset shows the location of Akkeshi Bay on Hokkaido Island, northern Japan.

Figure 2. Dendrogram (below) showing similarity of sampling localities based on species presence/absence, and a map (above) showing the geographical distribution of three groups of sampling localities (circled) that are less than 70% similar in species composition between groups.

Figure 3. Electra korobokkura Nikulina, 2006. (A–C) NHM 2006.2.27.1; (D) NHM 2006.2.27.2. (A) Colony fragment with uniserial branches; (B) colony fragment with anastomosing, multiserial branches; (C) zooids without spinous processes; (D) zooids with spinous processes. All unbleached. Scale bars: 2 mm (A, B); 1 mm (C); 0.5 mm (D).

Figure 4. Electra arctica Borg, 1931. ZIRAS 36/50535. Colony on rock collected by A. V. Grischenko, 12 September 1992, Sea of Okhotsk, western Kamchatka shelf (57°36.039N, 156°9.009E), depth 78–81 m. (A) Portion of colony showing anastomosing, narrowly multiserial branches; (B) autozooids and kenozooids; (C) enlargement of autozooids and kenozooids; (D) autozooids with operculum in place and kenozooids with nearly completely closed aperture. Specimen lightly bleached. Scale bars: 2 mm (A); 1 mm (B); 0.5 mm (C, D).

Figure 9. Cauloramphus cryptoarmatus n. sp. (A, C, E) NHM 2006.2.27.14; (B, F) NHM 2006.2.27.31; (D) NHM 2006.2.27.13. (A) Colony margin with developing zooids, unbleached; (B) zooids at colony margin in interaction with Cribrilina annulata, showing numerous additional avicularia developing along vertical walls from pore chambers, bleached; (C) autozooids, unbleached; (D) autozooids, showing strongly developed granulated cryptocyst, bleached; (E) two zooids showing details of avicularia and spines, unbleached; (F) ancestrula surrounded by periancestrular zooids, bleached. Scale bars: 0.5 mm (A–D, F); 0.4 mm (E).