ON RECENT SPECIES OF SPIRASERPULA REGENHARDT, 1961 



67 



Spiraserpula zibrowii sp. nov. 

 (Figs. 12, A-N; 3, O; P1.4, A-D) 



Material examined. 



Curacao (Neth. Ant.): 1. Lagoon of San Juan, E, raised reef, 

 lagoon side, Halimeda present, limestone cobbles, 10-15 cm; 

 from up to 20 cm deep crevices between cobbles, legit H. A. 

 ten Hove, 29.vi.1970, Stn. 2043 [HOLOTYPE & 

 PARATYPES 3-5: ZMA V.Pol. 3707; PARATYPES 1 

 (slide), 2 (worm & tube fragments), and 7 (empty tube: 

 BM(NH) 1992.148-150); PARATYPE 6: USNM 130980 

 (unopened tube)]. 



Bonaire (Neth. Ant.): 2. Kralendijk, Flamingo Beach Hotel, 

 from corals, partly in sand, 45 m, legit H. A. ten Hove, 

 27.vii.1970, Stn. 2115D, (4 empty tubes, BM(NH) 

 1992.151-155). 3. 250 m N of Witte Pan, sandflat below reef, 

 47 m, mainly from the side of boulders, partly buried in sand, 

 legit H. A. ten Hove, 3.vii.l970, Stn. 2117B (4 empty tubes, 

 ZMAV. Pol. 3708). 



Type locality. Curasao (Netherlands Antilles). 



Description. 



TUBES: Whitish, very tiny, and coiled upon themselves like 

 spirorbids, either individually (Fig. 12, B), or in mutually 

 bonded aggregations of a few individuals. The direction of 

 coiling may reverse (see below). A fine granular overlay is 

 present. Longitudinal ridges are absent, but fine, smooth, 

 transverse growth markings are present. Juvenile tubes are 

 white. Although older tubes are white posteriorly, they have 

 a greyish-brown overlay anteriorly. The diameter of an 

 individual coil is 0.73 mm, with a tube diameter of 0.18 mm. 

 The maximum tube diameter is only 0.44 mm, which is the 

 smallest among the known species of the genus. 



ITS consist of a serrated ventral ridge and an unserrated 

 dorsal ridge (Fig. 12, A,B). The ventral ridge may consist 

 either of a continuous row of serrations, or only of a short 

 row of small separate teeth (Figs. 12, A,B; 3, O). The dorsal 

 ridge is colourless and transparent, wedge- to Y-shaped in 

 cross-section, with its edges curved in places; it is spiral on a 

 columella-shaped axis when the tube is coiled upon itself. 

 Lateral ridges have not been found. The interior of the tube 

 may have a creamish lining. 



One tube is coiled in one direction proximally, and in the 

 opposite direction distally. In the proximal coil the ITS are 

 similar to those described above. However, the distal coil has 

 only a columella-shaped axis with a dorsal ridge, which 

 became detached from the tube and is shown in situ (Fig. 12, 

 E); a serrated ventral ridge is absent here. 



The mid-dorsal and mid-ventral longitudinal grooves of the 

 abdomen are applied to the unserrated dorsal ridge (Fig. 12, 

 D) and serrated ventral ridge of the tube, respectively. 

 WORMS: Measurements and meristic data are presented in 

 Table 12. 



The right branchial half of the holotype (left missing) 

 shows a rudimentary operculum. The latter is present on both 

 sides in the first paratype, but not in the second which is a 

 juvenile. The numbers of radioles on both sides are ?/3, 4/4 

 and 3/4, respectively. The pinnule-free tips are about 1/5-1/7 

 of their total length. 



Two clusters of prostomial ocelli are present. The numbers 

 of thoracic chaetal tufts on both sides in the three specimens 

 are: 7/7, 8/7 and 8/7, respectively. The thoracic membranes 

 end on chaetigers 3/3 in the holotype and 4/4 in the juvenile 

 paratype; they are damaged in the second paratype. Two 



Table 12 S. zibrowii sp. nov. Measurements and meristic data 

 from Holotype and two paratypes. 





Total 

 length 

 (mm) 



Thoracic 

 width 

 (mm) 





Abdomen 







Length 

 (mm) 



Number of 

 segments 



capillaries 

 on 



Holotype 

 Paratype 1 

 Paratype 2 



9.7 

 7.0 

 3.4 



0.23 

 0.18 

 0.18 



8.5 

 5.8 

 2.1 



54 

 43 

 27 



4 

 7 

 9 



translucent ventral thoracic glands are present, although not 

 as easily discerned as in some of the other species. 



There are 2 or 3 fully developed bayonet chaetae per side 

 in the juvenile, 4 in the older specimens. They have moder- 

 ately long serrated blades, an unserrated notch which is about 

 1/4-1/5 the length of the blade, and 4 or 5 somewhat large 

 teeth and some accessory ones on the basal boss (Fig. 12, F,I; 

 PI. 4, A). The thoracic uncini have a single row of 6-7 teeth 

 (PI. 4, B). Anterior abdominal uncini bear a cluster of small 

 teeth in two to seven rows at their posterior ends, and a single 

 row of larger teeth anteriorly; this type of uncini may occur in 

 juvenile specimens also (Fig. 12, J-M). The posterior abdomi- 

 nal uncini are, however, similar to those of the other species 

 in being rasp-shaped, with 6 transverse rows of 2-5 teeth 

 each, except for the single anterior tooth (Fig. 12, O; PI. 4, C). 

 The abdominal flat trumpet chaetae number about 5 per 

 bundle. Their somewhat triangular, curved distal ends are 

 thickened and hooked at one end, and drawn out into an 

 acute angle at the other (Fig. 12, N; PI. 4, D). Up to 54 

 abdominal segments are present, the last 4-9 with capillary 

 chaetae. 



Remarks. The collections from Bonaire, a mere 50 km from 

 Curasao, consist of a total of 8 empty tubes whose ITS are 

 identical with those of the present species. The largest tube 

 from Witte Pan has a coil diameter of 2.2 mm; two tubes have 

 erect portions with peristomes. Three tubes are white. The 

 fourth is creamish in colour, with a creamish interior lining. 

 Fine transverse growth markings are present on all. The 

 serrations of the ventral ridge are arranged on a low longitu- 

 dinal ridge in some of them. 



In the absence of worms, and the markedly different 

 habitat from which they were collected (at a depth of 

 45-47 m), these tubes cannot be conclusively identified as S. 

 zibrowii. 



Etymology, named after H. Zibrowius, who recognized 

 some of these small species as being new. 



Habitat and distribution. Appears to be a shallow water 

 species inhabiting crevices between boulders and their under- 

 sides in sandy areas close to coral reefs. Hitherto collected 

 from Curasao. Two uncertain records from Bonaire. 



Spiraserpula plaiae sp. 

 (Figs. 13, A-T; 3, K) 



nov. 



Material examined. 



Curasao (Neth. Ant.): 1. Salinja Fuik, near Ceru Preekstul, 

 open reef, coral debris, 33 m, from limestone boulder on 

 sand, legit H. A. ten Hove, 18. ix. 1970, Stn. 2088A (HOLO- 

 TYPE & PARATYPES 1 & 5: ZMA V. Pol.3713; 



