80 



T.G. PILLAI AND HA. TEN HOVE 



present along each flank (Fig. 20, A). Transverse ridges are 

 present, which may be thickened in places, representing 

 peristomes (Fig. 20, B,F,G). Although broken into fragments 

 during collection, total lengths appear to have been between 

 30-40 mm, and their maximum external diameters up to 

 about 3.0 mm. Their fractured ends show two concentric 

 layers of different consistency and thickness, an inner one 

 that is more vitreous and transparent than the outer which is 

 white and opaque. Their lateral margins are fragile and 

 chambered, with thin walls. 



The posterior ends of the tubes are coiled. ITS consist of a 

 low unserrated dorsal ridge, and a serrated ventral ridge 

 (Fig. 20, D-G). The latter may be represented by a row of 

 separate teeth (Figs. 20, D; 3, J). 



worms: The total length of the worms, based on the frag- 

 ments, exceeds 15.0 mm. The branchial crown is 4.0-5.0 mm 

 long, and each side bears 8-10 radioles and an operculum or a 

 rudimentary operculum. The opercular peduncle is long and 

 slender, of the same thickness as the radioles. One of the 

 specimens has a well-developed operculum on one side, and 

 another, much smaller, but similar operculum on the other. 

 The operculum is big and short, massive, bell-shaped, and 

 slightly concave distally. The radii end in large, rounded 

 marginal lobes, and range from 10 to 15 in number (10 in 1, 

 11 in 3, 12 in 1, and 15 in 1). The number of thoracic segments 

 per side varies from 10 to 14. A pair of small ocellar clusters is 

 present. Collar large, roughly divided into three large ventral 

 lobes and a pair of latero-dorsal lobes. Thoracic membranes 

 are broad up to the third segment, after which they narrow, 

 and do not form an apron. 



The longest opercular peduncle (holotype) together with 

 its operculum is 5.5 mm long. The operculum (Fig. 21, 

 A,C,D) is separated from the peduncle by a faint constric- 

 tion, where the peduncle is only 1/2-1/3 the diameter of the 

 base of the operculum. The variations in the dimensions of 

 opercula of the older specimens are as follows: length: 

 0.6-0.7 mm; width: 0.55-0.6 mm. They are bell-shaped, with 

 a small shallow concavity distally. They have a thick and 

 transparent cuticle (Fig. 21, A,C,D). The second radiole of 

 the opposite side is modified into a rudimentary operculum 

 (Fig. 21, B). The radioles end in short pinnule-free tips which 

 are about 1/10— l/15th the total length of the radioles (Fig. 21, 

 A-C). 



One of the specimens, a juvenile, provides an indication of 

 the possible ontogenetic changes in the operculum of this 

 species. Unlike in the adults, where peduncle and operculum 

 are markedly separated from each other, the slender 

 peduncle of the juvenile merges gradually into the base of the 

 operculum. In addition, the shape of the latter is an elongated 

 funnel, and its distal end is convex (Fig. 21, E). 



The collar fascicles may bear up to about 5 fully formed 

 bayonet chaetae and one developing deep within. Each 

 possesses a long serrated blade, a short unserrated notch, and 

 several moderately large teeth on the basal boss (Fig. 21, 

 F-K). Thoracic uncini show 5-6 teeth in side view; however, 

 in oblique edge view it is evident that they are saw-rasp 

 shaped, with an anterior single row and a posterior cluster of 

 teeth (Fig. 21, L). This is more clearly seen in the anterior 



abdominal uncini (Fig. 21, M). In side view, the number of 

 teeth in the latter vary from 4 or 5 towards the lateral end of 

 the torus to 7 at the dorsal end. Flat trumpet chaetae number 

 9-11 per bundle. Their distal ends terminate in a slender 

 hook-shaped process on one side and are drawn out into an 

 acute angle on the other (Fig. 21, N). 



Etymology. As suggested by Zibrowius (pers. comm.), the 

 species is named after its collector, P. Vasseur. 



Habitat and distribution. A reef dweller found on oyster 

 shells in submarine caves at depths of around 55 m. Hitherto 

 collected only from the Mozambique Channel. 



Spiraserpula deltoides sp. nov. 



(Figs. 22, A-N; 3, C) 



Material examined. 



Lesser Sunda Islands, Sumba (Indonesia): Snellius II 4.051, 

 NE coast of Sumba, E. of Melolo 09°53.5'S 120°42.7'E, 

 75-90 m. (HOLOTYPE & 1 PARATYPE (empty tube): 

 RMNH 18296; 3 PARATYPES: ZMA V. Pol. 3736; 

 2 PARATYPES: BM(NH) 1992.37 & 38). 



Type locality. Sumba (Indonesia). 



Description. 



TUBES: White, small, and spirally coiled upon themselves. 

 They are squarish in cross-section, smooth and rounded 

 dorso-laterally, and with a shallow longitudinal depression in 

 between (Fig. 22, A). They have an extremely fine granular 

 overlay, which can only be seen at certain angles of illumina- 

 tion, and very fine transverse grooves. The coil diameter is 

 generally about 3 mm, maximally 9 mm; the maximum exter- 

 nal tube diameter is generally 0.7 mm, maximally 1.3 mm. In 

 two of the tubes an inner transparent lining was observed. 



ITS consist only of a serrated dorsal ridge along the convex 

 wall of the tube (Figs. 22, B,C; 3, C). The serrations are 

 delta-shaped, mostly separate, and opaquely white in colour. 

 worms: The holotype (Fig. 22, D) is 5.0 mm long, 0.35 mm 

 wide in the thorax and its abdomen is 3.2 mm long. One 

 paratype is incomplete posteriorly, the other is 8.0 mm long, 

 with an abdomen of 3.5 mm. Some measurements and counts 

 are given Table 17: 



The operculum is bell-shaped, with a shallow distal concav- 

 ity extending inwards as far as the inter-radial grooves. The 

 radii end in rounded marginal lobes, the constriction between 

 operculum and peduncle is sharp, and the diameter of the 

 distal end of the peduncle is about 1/2-3/4 that of the 

 proximal part of the operculum (Fig. 22, D-G). The rudimen- 

 tary operculum is 1.5 mm long, thread-shaped. The radioles 

 end in short pinnule-free tips, about 1/7 the total length of the 

 radioles. Two clusters of prostomial ocelli are present. It is 

 difficult to determine whether ventral thoracic glands are 

 present. Thoracic membranes do not extend to the end of the 

 thorax, but exactly where they end cannot be located, it may 

 be at the 7th chaetiger in one paratype. The abdomen of the 

 holotype has about 67 segments, with capillaries on the last 8 

 or 9; the complete paratype has 85 abdominal segments, 24 

 with capillaries. The abdomen of the incomplete paratype is 



Fig. 21 Spiraserpula vasseuri sp. nov. A, Holotype. B-N, Paratypes. A, The left branchial crown and three views of the operculum and its 

 slender peduncle. B, Left branchial crown and rudimentary operculum from another specimen. C & D, branchial crowns and differrent 

 views of the opercula of two other specimens. E, Two views of the convex operculum of a juvenile. F-K, Bayonet collar chaetae bearing 

 several teeth on the basal boss, and a short unserrated notch. L, Thoracic uncini, with more than one row of teeth towards their posterior 

 ends. M, Anterior abdominal uncini. N, Bundle of anterior abdominal chaetae with flat trumpet-shaped ends. 





