Spirobranchus cf. polytrema

Sun, Yanan, Ten, Harry A. & Qiu, Jian-Wen, 2012, Serpulidae (Annelida: Polychaeta) from Hong Kong, Zootaxa 3424, pp. 1-42 : 30-32

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https://doi.org/ 10.5281/zenodo.213363



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Spirobranchus cf. polytrema


Spirobranchus cf. polytrema not ( Philippi, 1844), Type A sensu Imajima 1977

( Figure 14 A–C View FIGURE 14. A – C , Figure 15 View FIGURE 15 A–E)

Spirobranchus cf. polytrema — Imajima 1977: 102 –106; Fiege and Sun 1999: 126 –129. Spirobranchus polytrema not ( Philippi, 1844) sensu Sun and Yang 2001 a: 200 –201.

Material examined. AM W41412 View Materials , 2 specimens (22 ° 21 ’N, 114 ° 17 ’E, Sharp Island, on dead coral, 6 m, May 21, 2009).

Description. TUBES: white, subtriangular with a flattened area of attachment in cross-section, with a small longitudinal additional tube (or hollow keel) on top, flanked by a row of pits, a lateral longitudinal ridge and a row of slits at either side ( Figure 14 A View FIGURE 14. A – C ). About 1.0 mm wide with lumen 0.4 mm, however, anterior part of tube missing.

BRANCHIAE: together only 7 radioles, 4 on the right side, 3 on the left, arranged in a circle. Terminal filaments long, about three times longer than pinnules, approximately 0.5 mm. Branchial eyes not observed.

PEDUNCLE: smooth, flattened in cross-section, bearing a pair of wings, fringed along anterior margin with 4–6 digitiform processes. Inserted just below left branchial lobe.

OPERCULUM: with a fleshy, slightly translucent bulbous base and a tilted cone-shaped cap ( Figure 14 B–C View FIGURE 14. A – C , Figure 15 View FIGURE 15 A). Length of the operculum about 1 mm, width 0.5 mm.


THORAX: with 7 chaetigers, 6 uncinigerous. Collar chaetae bayonet type, with striated blade and numerous small teeth forming squarish emboss at base of blade, and limbate chaetae. Other thoracic notochaetae limbate capillaries ( Figure 15 View FIGURE 15 B). Uncini along entire thorax saw-shaped 9 to 10 saw-shaped, incidentally with 3 to 4 teeth above peg, anterior peg gouged ( Figure 15 View FIGURE 15 C). Tori of similar size along thorax, approaching each other posteriorly, leaving a ventral depression.

ABDOMEN: incomplete. Uncini of anterior and mid-body rasp-shaped, with 10–12 teeth seen in profile, 3 teeth in a row, anterior peg gouged and curved underneath ( Figure 15 View FIGURE 15 D). Chaetae true trumpet-shaped, abruptly bent distally, with two rows of denticles separated by a hollow groove and forming long lateral spine ( Figure 15 View FIGURE 15 E).

SIZE: incomplete specimens, up to 8.8 mm long and 1 mm wide.

COLOUR: in ethanol pale yellow, with brown operculum.

Habitat. Depth: 3–6 m, on dead coral skeletons.

Remarks. The occurrence of the temperate/subtropical Atlantic/Mediterranean species Spirobranchus polytrema ( Philippi, 1844) in tropical Asian seas is rather doubtful; it is more likely that similar (cf.) material from these seas will prove to be genetically different. See discussions in Imajima (1977: 106) and Pillai (2009: 153) as well. Records of Spirobranchus cf. polytrema from the Indo-West Pacific include two morphotypes, type A and type B ( Imajima 1977; Fiege & Sun 1999), both have an operculum consisting of a fleshy proximal part (ampulla) and a distal calcareous cone with rounded knobs, but differ from each other by the shape of tube and peduncular wings. Our material resembles type A in the shape of peduncular wings and tube. However, the opercula have a single tip to their calcareous cap instead of rounded knobs. Sun and Yang (2001 a, Figure 10 View FIGURE 10 ) figured specimens with and without rounded knobs on the distal calcareous cone of the operculum in their material from Hainan Island. To our knowledge this is the first report of a hollow keel, almost an additional tube, in the genus Spirobranchus (though Figure 16 View FIGURE 16 E of Fiege and Sun 1999 leaves room for an interpretation as one being present).

Distribution. Indo-West Pacific, Sri Lanka, Australia, Japan.














Spirobranchus cf. polytrema

Sun, Yanan, Ten, Harry A. & Qiu, Jian-Wen 2012

Spirobranchus cf. polytrema

Sun 2001: 200
Fiege 1999: 126
Imajima 1977: 102