76 



T.G. PILLAI AND H.A. TEN HOVE 



Table 15 S. caribensis from Grenada. Measurements and counts. 



Radioles 



Abdomen 



Total Thoracic Number 



Specimen length width Length Length of Capillaries 



no. (mm) (mm) (mm) No. (mm) segments on 



1 



9.2 



0.5 



2.0 5/5 6.6 



50 



44 



2 



8.1 



0.5 



1.2 4/3 4.7 



30 



7 



3 



3.1 



0.35 



0.6 3/3 1.8 



35 



10 



lost their tapered tips through abrasion may appear some- 

 what like the bayonets of S. caribensis from elsewhere 

 (Fig. 16, E, K; PI. 5, C-E), but the newly formed bayonets, 

 within the fascicle, possess tapered tips. 



Habitat and distribution. Appears to inhabit shallow 

 water and capable of withstanding the silty conditions found 

 in mangrove backwaters. It was found on the inside of a dead 

 oyster shell covered with much silt. 



Remarks. The extensively branching tubes and differences 

 in the collar chaetae initially led us to consider the Grenada 

 material as possibly belonging to a distinct species. However, 

 branching as such, although inconspicuous, was also subse- 

 quently observed in some specimens of S. caribensis from 

 Bonaire (Stn. 2123) and Curacao (Stns. 2090, 2096,75-38; see 

 above), in S. paraypsilon from Curacao (lO.i.90). Moreover, 

 S. snellii, described later in this paper, revealed a schizont 

 with parent in one tube. By itself, therefore, branching 

 cannot be a good character to separate the Grenada material 

 as a distinct species. The fully formed bayonet chaetae, 

 including those within the fascicle, of S. caribensis proper, 

 have short dagger-shaped blades with blunt tips, while blades 

 of the Grenada material typically end in tapered tips. 

 Although the tip of a fully formed chaeta in the Grenada 

 material might be lost through abrasion (Fig. 16, E-K), those 

 deep within the fascicle are tapered. 



Further work on additional material is necessary to deter- 

 mine whether frequent branching of the tubes and the 

 features of the bayonet chaetae are consistent, and whether 

 there are other characters which would justify the separation 

 of the Grenada material into a distinct species or not. 



Spiraserpula nudicrista sp. nov. 



(Figs. 17, A-N; 18, A-O; 3, F; PI. 3, A-D) 



Material examined. 



Bonaire (Neth. Ant.): 1. Karpata, reef, cryptic, 10 m, legit H. 



A.ten Hove, 9.xi.l988, (HOLOTYPE & PARATYPE: 



ZMAV.Pol.3711). 



Curacao (Neth. Ant.): 2. Savonet, E of Boca Braun, reef, no 



sand, about 22 m, from corals, some dead, legit H. A. ten 



Hove, 28.xi.1970, Stn. 2101 (PARATYPES 2 & 3: BM(NH) 



1992.61 & 62). 



Type locality. Bonaire (Netherlands Antilles). 



Description. 



tubes: White to creamish white and have a conspicuous 

 granular overlay (Fig. 17, A,E,M). They may be covered over 

 by encrusting calcareous organisms. They are trapezoidal in 

 cross-section, with two longitudinal ridges along the crest of 

 the tube and one along each flank (Fig. 17, A). The maximum 

 external tube diameter of the holotype is 1.0 mm. 



ITS consist of an unserrated ventral ridge which is rounded 

 and smooth towards its middle (Figs. 17, H; 3, F), from where 

 it decreases in thickness and height both anteriorly and 

 posteriorly (Fig. 17, C-E, F-G). A dorsal ridge is generally 

 absent, even on the convex pulley-shaped posterior end 

 (Fig. 17, I). However, paratype 1 from Bonaire showed some 

 isolated dorsal teeth. The mid-ventral longitudinal groove of 

 the abdomen (Fig. 17, M) is applied to the unserrated ventral 

 ridge . 



worms: Only two worms were yielded by the tubes from 

 Bonaire. The complete holotype has a total length of 

 15.6 mm, a thoracic width 0.7 mm, an abdominal length 

 11.9 mm and about 101 segments, with capillaries on the last 

 7. The radioles are 2.5 mm in length, and their pinnule-free 

 tips of 0.6 mm are comparatively long (Fig. 17, L, N). The 

 paratype is incomplete posteriorly. 



The holotype has 9 pairs of radioles while the paratype has 

 8 pairs. Both specimens have a short filamentous rudimentary 

 operculum on each side (Fig. 17, L). Two clusters of prosto- 

 mial ocelli are present, and are seen as conspicuous brown 

 patches through the collar (Fig. 17, J,K,M). This is in contrast 

 to the other known members of the genus in which they can 

 be seen when viewed from the anterior end with the radioles 

 removed or when mounted. 



Both specimens have 8 pairs of thoracic chaetal tufts, and 

 the thoracic membranes end on the fourth chaetiger on the 

 left (Fig. 17, K) and the 5th on the right. Ventral thoracic 

 glands appeared to be absent. 



The collar fascicles of the holotype possess four bayonet 

 chaetae with long serrated to pilose blades and several conical 

 teeth on the basal boss (Fig. 18, A-D; PI. 3, A). There may be 

 a number of accessory teeth arranged around the bases of the 

 larger teeth, which are lacking in the paratype (Fig. 18, E-G). 

 The unserrated notch is short. Thoracic uncini (Fig. 18, H; 

 PI. 3, B) and anterior abdominal uncini (Fig. 18, I; PI. 3, C) 

 possess 4 or 5 teeth arranged in a single row. There are about 

 4 flat trumpet chaetae in each abdominal fascicle (Fig. 18, 

 J;P1.3, D). An anterior hook, as in most of the species of the 

 group, cannot be discerned, all distal teeth appearing more or 

 less equally developed. 



Tubes of the specimens from Curacao are similar to those 

 from Bonaire with regard to colour, form and ITS (Fig. 18, 

 K). Their maximum external diameters are 1.1-1.2 mm. Two 

 of them yielded worms which are incomplete posteriorly. 

 Some data from them are presented in Table 16. 



Both specimens possess a rudimentary operculum on each 

 side (Fig. 18, L,M). Bayonet collar chaetae (Fig. 18, N,0), are 

 similar to those of the specimens from Bonaire, although 

 their basal bosses are somewhat stouter. 



Remarks. A small fragment from the inside of the coil of 



Fig. 18 Spiraserpula nudicrista sp. nov. A-J, From Bonaire. A-D, Bayonet chaetae, holotype. E-G, Three, out of five, bayonet chaetae 

 from paratype. H-J, from paratype: H, Thoracic uncini; I & J, flat trumpet-shaped chaetae and uncini from anterior abdomen. K-O, From 

 Curaao. K, Tube, with granular overlay, external longitudinal ridges, and internal ventral longitudinal ridge seen through fractured end. L, 

 Branchial crown of older specimen with pair of rudimentary opercula. M, Branchial crown of younger specimen, with pair of shorter 

 rudimentary opercula. N & O, Two, out of four, bayonet chaetae. 



