Crisia guang n. sp.

(Figs 3–6)

lsid:zoobank.org:act: 1E1DF6A1-190C-4689-AA38-5377226CC530

? Crisia eburnea: Mawatari & Mawatari, 1973: p. 97, text-fig. 3, pl. 1, figs 7, 8.

? Crisia eburneo-denticulata: Mawatari & Mawatari, 1973: p. 96, text-fig. 2, pl. 1, figs 5, 6.

v. Crisia eburneo-denticulata: Liu, Yin & Ma, 2001: 379, pl. 4, figs 3–5.

Diagnosis: Crisia with gonozooid occupying almost the entire width of the branch and brood chamber as long as 2–3 autozooids. Ooeciopore larger than an autozooidal aperture, facing frontally, oval, with a straight distal edge, and often adjacent to an autozooidal aperture.

Holotype. Specimen MBM 284486 from Yangkou (Laoshan) (Figs 3, 4).

Paratypes. MBM 284371 and MBM 284372 ( Lingshan Island) , MBM 284479 ( Haijiao, Lingshan Island) , MBM 284485 and MBM 284488 (Yangkou, Laoshan).

Additional material. More than 30 colonies, from samples MBM 0 92255, MBM 194665, MBM 194688, MBM 194759, MBM 194937 and MBM 194942 (Haijiao, Lingshan Island), MBM 0 92292, MBM 0 92315, MBM 0 92318 and MBM 188532 (Jiaozhou Bay), MBM 2843975 (Yangkou, Laoshan) and MBM 284367, MBM 284364 (Lingshan Island).

Etymology. Referring to the wide gonozooid occupying the full width of the branch; in Chinese phonetic transcription, ‘wide’ is guǎng .

Description. Width of internodes approximately 270–350 µm, length approximately 1.3–3.8 mm; approxi- mately 15–20 autozooids per internode. Autozooids approximately 230 µm long (the zooids attached to gonozooid can exceed its length, up to 320 µm), width approximately 80–100 µm. Apertures circular, approximately 58–68 µm in diameter, with peristome facing frontally. Pseudopores on the frontal wall slit-like (approximately 25 µm long by 2 µm wide), numerous and longitudinally oriented. Gonozooid as long as two to three autozooids, extending across entire branch width. The proximal part of the gonozooid (before dilation) is wider than the equivalent part of an autozooid. Ooeciopore frontally oriented, larger than an autozooidal aperture, oval, wider (ca. 115 µm) than long (ca. 50 µm), distal edge more or less straight, adjacent to the neighbouring autozooidal aperture. Pseudopores more numerous than in autozooids but similar in shape or size.

Remarks. The most similar species is Crisia denticulata (Lamarck, 1816), which based on Hayward & Ryland (1985) has a similarly extended gonozooid and a similar shape and position of the ooeciopore. The new species mainly differs in having a less convex gonozooid and in the lack of characteristic black joints between internodes. Moreover, C. denticulata has been reported only from Europe (Hayward & Ryland 1985).

Crisia eburneo-denticulata Smitt ms in Busk, 1875, distinctly differs in the position of the gonozooid, occupying approximately three-fourths of the fertile branch width, and shifted slightly towards the margin of the branch. One fully developed autozooid is always situated alongside the margin of the gonozooid. Crisia eburneo-denticulata has been reported mainly from the northern Atlantic (Brunel et al. 1998). The other occurrences of Crisia eburneo-denticulata in Asia are doubtful (e.g. Seo 2005), so it is highly probable that this species is absent from the western Pacific.

The specimens described and illustrated by Mawatari & Mawatari (1973) as Crisia eburnea as well as Crisia eburneo-denticulata show the same extension of the gonozooid and similar position and shape of the ooeciopore. These two species differ according to the original Mawatari & Mawatari’s (1973) description only in the size of the ooeciopore. This feature might be, however, just an extreme variant in a species with ooeciopores that vary greatly in size. As we do not have the original material at our disposal, the identification of these specimens remains uncertain.

The most distinctive feature of this species is the very large size of the ooeciopore on the extended gonozooid.

Occurrence. Haijiao (Lingshan Island), Jiaozhou Bay and Yangkou (Laoshan).