Cauloramphus dicki, Min, Bum Sik, Seo, Ji Eun, Grischenko, Andrei V. & Gordon, Dennis P., 2017

Min, Bum Sik, Seo, Ji Eun, Grischenko, Andrei V. & Gordon, Dennis P., 2017, Intertidal Bryozoa from Korea — new additions to the fauna and a new genus of Bitectiporidae (Cheilostomata) from Baengnyeong Island, Yellow Sea, Zootaxa 4226 (4), pp. 451-470 : 454-455

Cauloramphus dicki n. sp.

( Figs 2–5 )

Cauloramphus ‘Korea Baeng. sp. 1’: Dick et al. 2013: 33, 40, 41.

Etymology. Honorific for Dr Matthew H. Dick, Hokkaido University, Japan, who has greatly advanced knowledge of bryozoans in the North Pacific, especially the genus Cauloramphus .

Material examined. Holotype: NIBRIV0000325931, Yeonhwa-ri , 37.9378° N, 124.6233° E, Baengnyeong Island, 27 November 2007, low tide, collected by B.S. Min and A.V. Grischenko . Paratypes: NIBRIV0000711262, same collection data as for the holotype. Other material: Woosuk University collection—Baengnyeong Island: Dumujin (27 colonies), Yeonhwa-ri (21 colonies), mostly on rocky substrata, but also on plastic debris, shell and crustose coralline algae ( Clathromorphum ).

Description. Colony encrusting, unilaminar, up to 20 mm in diameter, brownish when dried. Autozooids contiguous, arranged in quincunx, more or less elongate-oval and tending to be widest in proximal half; interzooidal boundaries clearly defined by furrows. Gymnocyst very narrow laterally or not evident in frontal view, slightly developed proximally or not at all, smooth, bearing 10–16 periopesial spines; these more or less straight, obliquely angled part way across opesia; distalmost 3–5 spines stouter and more vertical; spine bases not dark. Cryptocystal rim inside and between periopesial spine bases, coarsely granular-tubercular except in distal quarter, of same width throughout except distally where it is narrowed to the point of absence. Opesia large, oval. Operculum comprising a transversely D-shaped flap, somewhat high-arched, at distal end of membranous frontal wall. Avicularia single or paired, fusiform in frontal view, asymmetrically clavate in lateral view, placed between the 2nd and 3rd, or 3rd and 4th, periopesial spines on either side, the mandibular-opesial surface steeply slanted, facing proximolaterally; rostrum and mandible acute; basal stalk of avicularium cuticular. Ooecium vestigial, comprising a small transversely arcuate structure with a flattened area of interior wall and a tiny pore, having 1–4 short distal lobes between spine bases. Communication pore areas in open-fronted pore-chambers along the base of the distolateral walls, with 1–2 such chambers mid-distally and 2–3 on each side distolaterally. Ancestrula not seen.

Measurements. ZL, 358–474 (410) µm; ZW, 230–313 (276) µm; OpL, 279–341 (301) µm; OpW, 144–198 (174) µm.

Remarks. Cauloramphus dicki n. sp. is very similar to material from Akkeshi Bay, Hokkaido, Japan, attributed by Grischenko et al. (2007) to Cauloramphus spinifer ( Johnston, 1832) , a species first described from Britain that is nominally widespread in the northern Pacific (Dick & Ross 1998; Grischenko et al. 2007). The specimens from Japan have the same total number of spines, similar avicularia (though less elongate), and the same relative proportions of gymnocyst and gymnocyst, but the vestigial ooecium is different. Whereas it is smooth and concave with a crest in putative C. spinifer from Hokkaido ( Ostrovsky et al. 2007), that in C. dicki is flattened, with lobes extending between spine bases.

Furthermore, in a study comparing morphological divergence with genetic distance using cytochrome c oxidase I ( COI) sequences, Dick et al. (2013) showed that material from Baengnyeong Island here named as C. dicki was isolated from C. spinifer in the gene tree. It should be noted that the vestigial ooecium of C. spinifer from Europe has not been described, nor have COI sequences been obtained, so it remains to be demonstrated that this species really is in the North Pacific. [In passing, it should be noted that the specific epithet is sometimes rendered spiniferum (e.g. Hayward & Ryland 1998), but, whereas rhamphos (Greek, curved beak or bill) is neuter in gender, the Latinized form of the noun is masculine, hence spinifer is the correct spelling, as in several authors from O’Donoghue & O’Donoghue (1926) to Grischenko et al. (2007).]

Distribution. Korea: Baengnyeong Island. Japan: Akkeshi Bay, Hokkaido; low intertidal on hard substrata.

Figures

FIGURES 2 – 5. Cauloramphus dicki n. sp., Yeonhwa-ri. 2, Part of an unbleached colony with periopesial spines and three claviform avicularia (arrows); scale bar, 200 µm. 3, Frontal view of the mandible and opesial frontal membrane of an avicularium; scale bar, 20 µm. 4, Non-ovicellate zooids with periopesial spine bases; scale bar, 100 µm. 5, An entire autozooid and parts of neighbours showing two vestigial ooecia, each with a distal extension between a pair of spines; arrows indicate a flattened area of interior wall and a pore; scale bar, 200 µm.