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Zoo1.J. Linn. Soc., 4 8 , p p . 363-385. With 13figures August 1969 Spirorbinae (Polychaeta : Serpulidae) from Chios (Aegean Sea) JULIE H. BAILEY Zoology Department, University College of Swansea Accepted for publication October 1968 Twelve species are described, of which two are new, viz. Spirorbis (Janua)gnomontcus and Spirorbis (9.) parvulus, and three others have been recognized only very recently, viz. S. (Pileolaria) clavus, S. ( P . ) endoumenris, S . (P.) heteropoma. Some such as S. (J.) corngatus and S. ( P . )koehleri were widely distributed between depths of M O m, but others showed a tendency towards depth zonation, with S.(J.)pagenstecheriabundant in shallow and S. (Spirorbis)cuneatus in somewhat less shallow water. S. ( P . ) pseudomilitaris and S. (Marsipospira) striatus were confined to greater depths except where the former occurred amongst ships fouling and the latter in a dark cave. S. (P.) militaris seems rather uncommon. A remarkably high percentage of the species (over 80%) are opercular incubators. Outside the Mediterranean, the only areas known to have similar percentages are Ceylon and the West Indies, suggesting that the habit may have originated in the Sea of Tethys. CONTENTS Introduction and methods . Key to the species observed. . Descriptions of species . Spirorbis (Spirorbis) Cuneatus . Spirorbis (Marsipospira) striatus . Spirorbis (Pileolaria) militaris . Spirorbis (Pileolaria)pseudomilitaris . Spirorbis (Pileolaria) heteropoma . Spirorbis (Pileolaria) clavus . Spirorbis (Pileolaria) koehleri . Spirorbis (Pileolaria) endoumensis . Spirorbis (Janua)pagenstecheri . Spirorbis (Janua) corrugatus . Spirorbis (Janua) gnomonicus sp. nov. Spirorbis (Janua) paruulus sp. nov. Distribution and relative abundance . Zoogeographical considerations . Acknowledgements . References . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . PAGE 363 365 366 366 368 369 369 371 372 373 374 375 375 376 377 378 380 383 383 INTRODUCTION AND METHODS Accounts of Spirorbinae from the Mediterranean include those of Claparkde (1868), Marion & Bobretsky (1875), Marion (1879), Caullery & Mesnil (1897), Harris & Knight-Jones (1964), Thiriot-Quibvreux (1965), Zibrowius (1967, 1968) and Harris (1968a), but all these deal with species found in the western part of the Mediterranean, mainly from France and Naples. The nearest records to the Aegean are those of Sterzinger (1909) and Pixel1 (1914), from Suez, Fauvel(l955) from Israel and Sterzinger (1910) from the northern Adriatic. Nothing seems to have been published about the Spirorbinae of the Aegean. JULIE H.BAILEY 364 Chios is one of the larger Greek islands and lies at 38'20" and 26'00'E, about five miles west of the nearest point on the Turkish coast. Collections of Spirorbinae were made at several locations off the southern and south-western coasts and from one more northern area, during August 1967, by an expedition from the University College of Swansea, sent at the invitation of the Chios Committee. The main collecting localities are indicated in Fig. 1. The expedition's camp site was by Station 1, at Emborios. 10 miles lOkm FIGURE 1. Map of Chios showing collecting stations. 1, Emborios bay, cave and cobble beach; 2, submarine peak; 3, Cape Mastikho;4, Venetico; 5, MoulaPetra;6, Nisos Aspro;7,Foradhas; 8, Nisos Margaritis. T o collect Spirorbinae, rocks, stones, shells, erect plants and incrustations of coralline algae were picked up or prised out of crevices by divers, examined briefly and taken ashore. They were then sorted over, usually with the help of magnlfying lenses, and most of the Spirorbis were scraped with a knife into specimen tubes, to reduce the volume of preserved material. The recorded notes did not usually include details of the substrata sampled, but gave depths and locations. Some of the collections were from a succession of shallow depths near Emborios, one was from a shore-line cave, another from a local fishing vessel and the rest from various greater depths down to about 60 m. Most collections were preserved in sea-water with 5% formaldehyde and these showed, even after five or six months, colours which have been noted in descriptions of species. Some other material was preserved in 50% alcohol, however, to ensure that calcareous opercular structures were not dissolved. Polyvinyl-lactophenol was used as a mountant, for laboratory examination of setae and uncini, the detailed structure of which was studied by phase-contrast microscopy, using oil-immersion and iodinequartz illumination. SPIRORBINAE FROM THE AEGEAN SEA 365 Twelve species were recorded, eight of which were sinistral and four dextral. Five of the twelve had not previously been described, but correspondencewith other specialists revealed that two of the five were known from Marseille (Zibrowius, 1968) and . remaining two are described here as new. another from Naples (Harris, 1 9 6 8 ~ )The The Spirorbinae are here regarded as comprising the single genus Spirorbis, which may be split into several subgenera according to the scheme proposed by Bailey (1969 u). Compared with Spirorbinae from the Atlantic and most other areas, a remarkably high proportion of the Chios species incubate their embryos in opercular brood chambers, and the physiological and zoogeographical implications of this peculiarity are discussed later. KEY T O THE SPECIES OBSERVED Mouth of tube faces clockwise . Mouth of tube faces anticlockwise 1. 2. (1) Operculum has a massive conical talon . . Operculum lacks a massive conical talon 3. (2) Tube opaque (p. 367) . Tube translucent (p. 368) . . . . 13 . . 3 4 . S . cuneatus Gee S . striutus (QuiCvreux) 4. (3) Flat to concave opercular plate, peg-talon and no embryos Embryos in a calcareous brood chamber. 2 . . . - 5 8 . . 6 Narrow talon, with a row of spines projecting from one side (p. 370) juvenile S. militaris Clapartde 5. (4) Simple peg-like talon 6. (5) Peg-talon reaches floor of ampulla and passes through it into the stalk (p. 372) . . juvenile S. clavus Harris Peg-talon does not reach floor of ampulla . . 7 7. (6) Tube with three longitudinal ridges, peg-talon small and eccentric (p. 371) . . juv. S. heteropomu Zibrowius Tube smooth or with indistinct longitudinal ridges ; peg-talon small and eccentric (p. 370) . juv. S. pseudomilitaris Thiriot-QuiCvreux . 8. (4) Brood chamber associated with a stack of two or three concave opercular plates . . Brood chamber a simple calcareous chamber . . 9 10 9. (8) Two or three opercular plates, stacked and interlocking; eggs incubated below them in a calcareous sac (p. 373) S. koehleri Caullery & Mesnil Two or three opercular plates stacked, but not interlocking; eggs incubated between the plates (p. 374) . . S. endournensis Zibrowius . 23 JULIE H. BAILEY 366 10. (8) Brood chamber with one or more spiny processes Brood chamber lacking spines (p. 372) . . 11. (10)Brood chamber with many distal spiny processes Brood chamber with a single distal process (p. 371) . . 11 S. clavus Harris . 12 S . heteropoma Zibrowius 12. (1 1) Brood chamber flat or slightly domed, witha peripheral spiny rim (p. 370) S . pseudomilitaris Thiriot-Quikvrewr Brood chamber helmet-shaped, with some spines forming a peripheral rim and others scattered over the surface (p. 370) . S . militaris Clapartde 13. (12) Tube with three longitudinal ridges . Tubesmpoth . . . 14 17 14. (13) Opercular plate flat, with a round peg-like talon Opercular plate concave or convex . S . pagenstecheri Quatrefages . 15 15. (14)Opercular plate with a bilobed eccentric talon (p. 375) juvenile S. corrugatus Caullery & Mesnil . . 16 Operculum lacks a talon 16. (15) Opercular plate with no distal process, except for a thin peripheral . older S. corrugatus Caullery & Mesnil collar (p. 375) , Opercular plate with a distal median crest (p. 376) S. gnomonicus sp. nov. 17. (16) Concave plate forming the top of a brood chamber containing only about two embryos; mouth of tube coiled into an almost apical position (p. 377) . . S.parvulus sp. nov. DESCRIPTIONS OF SPECIES Genus Spirorbis Daudin (1800) Hermaphrodite serpulids living in a dextrally or sinistrally coiled tube. The thorax has no more than four segments, and the opercular stalk lacks pinnules. Subgenus Spirorbis sensu stricto Sinistral tube; thorax of three segments; each collar seta with a proximal fin and a distal toothed blade ; egg-string incubation inside the tube. ' Spirorbis (Spirorbis) cuneatus Gee (Fig. 2) Sinistral, white tube, 1-1-5 mm in greatest diameter across the coil, with three longitudinal ridges forming teeth over the mouth. The last whorl may partially overlap previous whorls and forms a flange against the substratum. SPIRORBINAE FROM THE AEGEAN SEA 367 The operculum has a flat or slightly concave plate and a massive conical talon with three pointed lobes, one of them on each side and the other terminal. Three thoracic segments. Collar setae each with a cross-striated distal blade and a proximal fin. Second and third segments have simple setae, in addition to which the third has recurved, toothed setae. Ten to fourteen abdominal segments with finely toothed geniculate setae. Egg strings incubated in the tube. A B "i a E P in N C H FIGURE 2. Spirorbis (Spirorbis)cuneatus. A, Tube; B, face view and C, lateral view of operculum; D, collar seta; E, capillary seta of first segment; F, seta of second or third segment; G, seta of third segment; H, thoracic uncinus; J, abdominal uncinus; K, abdominal seta. The specimens agreed closely with Atlantic coast material studied by Gee (1964) and with the description of Zibrowius (1968) from Marseille. The lobes of the talon vary somewhat in their arrangement and it seems possible that this species provided the material on which Caullery & Mesnil (1897) founded their description of Spirorbis mediterraneus. That older name might thus be adopted here (Nelson-Smith & Gee, 1966 ;Nelson-Smith, 1967), but Zibrowius (1968) reported from Marseille two specimens which were distinct from S . cuneatus and agreed perfectly with the original description of S . mediterraneus. They seemed to represent either a distinct species or immature and somewhat aberrant S . militaris. Pending further studies the older name should perhaps lapse, as having been based upon an inadequate description. Distribution elsewhere: Naples (Harris, 1968a) ; Marseille (Zibrowius, 1968) ; Costa Brava (Harris & Knight- Jones, 1964) ;west coasts of Britain. JULIE H. BAILEY 368 Subgenus Mursipospiru Bailey (1969a) Sinistral coiling ; tube usually translucent, with transverse ridges ; thoracic brood pouch with a stalk; traces of a fourth thoracic segment ;collar setae each with a fin and cross-striated blade ;abdominal setae brush-like. Spirorbis (Marsipospiru) striutus (Quitkreux) (Fig. 3 ) Sinistral translucent tube, with a round mouth and prominent transverse ridges. The last whorl partially covers the preceding whorls. Diameter across coil 1-2.5 mm. Slightly concave opercular plate, with a massive conical talon bearing a ventral spur, which is more developed in large specimens than in smaller ones, and two lateral lobes, each with a row of knobs. _I D F 0 N 0 E ni Ln 0 C FIGURE 3. Spirorbis (Mursipospiru) striutus. A, Tube; B, face view and C, lateral view of operculum; D, collar seta; E, capillary seta of first segment; F, seta of second and third segments; G, seta of third or (when present) of fourth segment; H, thoracic uncinus; J, abdominal uncinus; 11, abdominal seta. I n the original material from Roscoff, the type locality, the thorax has ‘three and three quarters segments’, the fourth segment being represented by a complete parapodium on the convex side and a neuropodium on the concave side. Most specimensfrom Chios, however, only have ‘three and a quarter segments’ (i.e. a neuropodium on the concave side only) ;but one of the larger specimens may be said to have three and a half, the extra half segment being represented by the neuropodia on both concave and convex SPIRORBINAE FROM THE AEGEAN SEA 369 sides. The rudiments of the extra thoracic segment probably develop during growth, as is known to occur in Spirorbis (Paralaeospira) malardi and Spirwbis (Paradexiospira) witreus (Crisp, Bailey & Knight-Jones, 1967). It is probable that the notopodium on the convex side of S. striatus at Roscoff appears during further growth, for the largest Chios specimens were smaller than those recorded from Roscoff. The absence of these parapodial rudiments from the Chios specimens seems better regarded as a neotenous trend, than as a basis for distinguishing them specifically from the Roscoff forms (see also Bailey, 1969a). Collar setae each have a proximal fin separated by a gap from a distal, cross-striated blade. The fin has three large and three smaller teeth. Setae on the second segment are simple blades, those on the third and fourth when present bear recurved hooks. The abdominal setae are brush-like. Eggs are redlorange and incubated in a thoracic brood pouch in the tube. This species differs from S. ambilateralis Pixell (1912), which has four complete thoracic segments, and S. racemoms Pixell (1912) which has three and a quarter and lacks lateral knobs on the opercular talon (see also Rioja, 1962). S. translucem Bailey (1968) also lacks rounded knobs laterally and has angular ridges instead. Distribution elsewhere : Roscoff and Cap Ferrat (France). Subgenus PiZeolaria Claparkde (1 868) Sinistral coiling ;incubation in an opercular brood chamber; three thoracic segments ; fin and blade collar setae (which may bear cross striations). Spirorbis (PiZeolaria)miZitaris Claparkde (Fauvel, 1927) Sinistral, smooth tube with a wide, round mouth, transverse growth lines and the whole spiral loosely coiled. Diameter across coil 1-3 mm. This species shows opercular dimorphism (Fig. 4). The opercula of two immature stages have previously been described as separate species (Zibrowius, 1967). The firstformed operculum has a three-pronged talon and was called s.cornuarietis (Caullery & Mesnil, 1897). The second stage has a long talon, with a row of projecting spines, and was called S. beneti Marion (1878). The brooding operculum develops below the 'beneti' type operculum as a calcareous dome. A frill of spines develops around the dome and the distal surface becomes covered with individual spines. There are three thoracic segments. The collar setae each have a cross-striated distal blade separated by a gap from a proximal toothed fin. The second segment has setae with simple blades, the third bears some simple setae and others with recurved teeth. Abdomen of 8-10 segments with geniculate toothed setae. Distribution elsewhere : English Channel, Madeira and Naples (Caullery & Mesnil, 1897) ;north-west Spain (Rioja, 1923) ; Mexico (Rioja, 1942). Spirorbis (Pileolaria) pseudomilitaris Thiriot-QuiCvreux, 1965 Tube sinistral, white and smooth, diameter of coil 1-2 mm. There is opercular dimorphism (Fig. 9, similar to that in S. militaris but with only one type of primary operculum. In immature specimens the opercular plate is concave, with an eccentric peg talon. The incubatory chamber can be seen developing under- JULIE H. BAILEY 370 FIGURE 4. Spirorbis (Pileolaria) miiitaris. A, Face view and B, side view of primary operculum (‘S.cornuarietis’ type); C, face view and D, side view of primary operculum (‘S.beneti’ type); E,‘S.bmeti’ type operculum which lay in the distal groove of F,which is a developing opercular brood chamber; G, side view and H,face view of a brood chamber with eggs. neath the plate, as a thin calcareous dome. The adult loses the primary plate and the flat-topped incubatory chamber has a peripheral frill of spines. There may also be a few spines placed more centrally on the distal surface. Three thoracic segments. Collar setae each with a cross-striated distal blade, separated by a gap from a proximal toothed fin.Second and third segments both have simple blades. Abdomen of 15-20 segments with geniculate toothed setae. C 1: FIGURE5 . Spirorbis (Pileo1aria)pseudotnilitaris.A,Face view and side view of primary operculum; B, primary plate with incubatory chamber developing underneath; C, views of incubatory chamber; D, views of chamber full of eggs. SPIRORBINAE FROM THE AEGEAN SEA 371 Distribution elsewhere:Villefranche, Toulon, Tamaris-sur-mer (Thiriot-Quikvrew, 1965); Marseille (Zibrowius, 1968); Naples (Harris, 1968a, as S. berkeleyanus). I n the French material the tube bears longitudinal ridges. Spirorbis (Pileolaria)heteropoma Zibrowius, 1968 (Fig. 6) Sinistral tube 1-2 mm in diameter, with two or three longitudinal ridges. The mouth is round and often coils up on previous whorls. There is opercular dimorphism. The primary plate is very similar to that of S. pseudomilitaris, with a concave plate and eccentric peg-talon. 0 FIGURE 6. Spirorbis (Pileolaria) heteropoma. A, Tube; B, face view of primary operculum; C & C1, two views of incubatory chamber full of eggs, with primary operculum still attached; D & D1, two views of another incubatorychamber full of eggs; E, collar seta; F, capillary seta of first segment ; G, seta of second or third segment;H, seta of third segment;J, thoracic uncinus; K, abdominal uncinus; L, abdominal seta. A domed chamber develops underneath this, forming a helmet-like calcareous brood chamber, with a distal spine. The peg of the talon remains attached to the spine until it is sloughed off. There are three thoracic segments. Collar setae each have a cross-striated distal blade separated by a gap from a proximal toothed fin.The second segment has simple setae, the third both simple and recurved toothed setae. Abdomen with 8-12 segments bearing geniculate setae. Tentacles tinged yellow, thorax red, hepatic region brown, abdomen pale yellow. Eggs in the domed opercular chamber pale yellow. 372 JULIE H. BAILEY Distribution elsewhere : Marseille (Zibrowius, 1968); Naples (Harris, 1968a as S . moerchi). Spirorbis (Pileoluria) cluvus Harris, 1968a (Fig. 7) Sinistral, white tube with two faint longitudinal ridges towards the inner curve of the whorl. Round mouth with a thickened rim, diameter of coil 1-2 mm. There is opercular dimorphism. In small individuals the operculum has an ampulla topped by an uneven calcareous plate, with a peg-like talon extending to the floor of the chamber and into the stalk. Prior to brooding the ampulla increases in length considerably, and the opercular plate and talon appear relatively smaller, so that the peg no longer reaches far into the ampulla. Calcareous thickening of the roof and walls takes place under the opercular plate. This plate eventually drops off, leaving the elongated ampulla borne eccentrically on the stalk and calcified except for one side. When incubating, the eggs can be seen clearly in this area and do not appear to be covered over. FIGURE 7. Spirmbis (Pileolaria) clawus. A, Tube; B. primary operculum; C, developing incubatory chamber;D, incubatory chamber with eggs; E, collar seta; F, capillary seta of first segment; G, seta of second and third segments; H, seta of third segment; J, thoracic uncinus; K, abdominal uncinus; L, abdominal seta. There are three thoracic segments. The collar setae each have a cross-striated, distal blade separated by a gap from a proximal toothed fin. The second segment has simple blades, the third a mixture of simple blades and recurved, toothed setae. Abdomen of 10-12 segments with simple, toothed setae. Tentacles colourless, thorax orange, hepatic region orange/yellow, abdomen colourless. Eggs in operculum yellow. Distribution elsewhere: at a depth of 55 m off Mergellina, near Naples (Harris, 1968~). SPIRORBINAE FROM THE AEGEAN SEA 373 Spirorbis (Pileoluriu) koehleri Caullery & Mesnil (Fig. 8) Sinistral, white tube with three obvious longitudinal ridges, which are divided into short spines along the outer whorl and form teeth over the round mouth. Operculum consists of two or three concave, calcareous plates, which interlock by means of a peg and socket arrangement at the periphery. Eggs are incubated below the last plate and the peg of this plate is elongated to form a keel, which contributes to the calcareous wall of the chamber. A fragile calcareous sac forms under this, interlockingwith the keel of the plate above, which thus helps to keep the eggs in the chamber. FIGURE 8. Spirorbis (Pileolaria) koehleri. A, Tube; B, operculum face view; C, incubatory chamber;D, incubatory chamber showing eggs ;E, collar seta ;F, capillary seta of first segment; G, seta of second or third segment;H, seta of third segment ;J, thoracic uncinus ;K, abdominal uncinus; L, abdominal seta. There are three thoracic segments. The collar setae each have a simple, distal blade, separated by a gap from a proximal fin of three large and six smaller teeth. The second segment has setae with simple blades, the third some with simple and others with recurved, toothed blades. The abdomen consists of 10-15 segments, bearing geniculate setae with large, rounded teeth. Tentacles pale yellow, thorax yellow/buff, hepatic region light brown, ovary yellow, rest of abdomen colourless, eggs in operculum pale yellow. Distribution elsewhere : La Ciotat ; Marseille (Zibrowius, 1968) ; West Indies (Bailey, 1969b). 374 JULIE H. BAILEY Spirorbis (Pileolaria) endournensis Zibrowius, 1968 (Fig. 9) Sinistral, white tube with three smooth l o n g i t u d d ridges, which extend over the mouth as teeth. The outer whorl lies flat against the substratum and forms a closely adherent peripheral flange. Diameter across coil 1-2 mm. Operculum bears one or more plates, each with a deep eccentric concavity, from which a peripheral projection extends proximally and rests in the concave part of the plate below. Eggs are incubated between the plates and calcareous walls are formed round the brood chamber by thin peripheral and proximal extensions of the plate which lies immediately above it. D FIGURE 9. Spirorbis (Pileolaria) endoumpnsis. A, Tube; B, side and rear views of opercular plate; C, operculum with eggs; C1,operculum after liberatinglarvae; D, collar seta; E, capillary seta of first segment; F, seta of second or third segment; G, seta of third segment; H, thoracic uncinus; J, abdominal uncinus; K, abdominal seta. There are three thoracic segments. Collar setae each have a distal blade, separated by a gap from a proximal fin, which comprises three large and five smaller teeth. Setae of the second segment have simple blades ; some on the third have simple blades and others recurved hooks. The abdomen has 12 segments, bearing geniculate setae with large rounded teeth. Distribution elsewhere :Marseille (Zibrowius, 1968). Subgenus Junuu Saint-Joseph Dextral coiling ;incubation in an opercular brood chamber, three thoracic segments ; collar setae without a gap between the fin and blade, or lacking a fin altogether. SPIRORBINAE FROM THE AEGEAN SEA 375 Spiror6is (Janua)pagemtechmi Quatrefages (Fauvel, 1927) Dextral, white tube with three longitudinal ridges, the last whorl not overlapping previous whorls. Diameter across coil 1-1.5 mm. Opercular plate flat, with a peg-like eccentric talon. Opercular walls form the sides of an incubatory chamber, but do not appear to be strengthened by calcareous deposits. There are three thoracic segments. The collar setae are simple geniculate blades, each with a fin not separated from the blade. The blade is not cross-striated. Setae of the second and third segments have simple blades without fins. Abdomen has 6-10 segments bearing geniculate setae with finely toothed blades. Distribution elsewhere : west Mediterranean, north-west coasts of Europe, Israel (Fauvel, 1955), Ceylon (de Silva, 1965), Galapagos (Bailey & Harris, 1968). Spirmbis (Janua)corrugutus Caullery & Mesnil (Fig. 10) Dextral, white tube with three longitudinal ridges and a round mouth. The last whorl may partially overlap the preceding whorl. 1 E F G H FIGURE 10.Spirorbis (~anua) corrugatus. A-D, Views of opercula with developing embryos at different stages; E-H, views of juvenile opercula. Opercular plate slightly concave, bearing in young individuals a peripheral talon which is often bilobed. When the plate forms the top of a brood chamber, however, it often lacks any talon, but has a distinct rim protruding all round the periphery. The side walls of the brood chamber are strengthened distally by a thin calcareous wall, which has numerous minute perforations. A basal plate is formed under a brood chamber containing well developed embryos. There are three thoracic segments. The collar setae are simple geniculate blades, those on the convex side being larger, with cross-striations, whilst those on the concave side lack cross-striations. The second and third thoracic setae are simple blades. The abdomen has 8-14 segments, bearing geniculate setae with fine teeth. JULIE H. BAILEY 376 These abundant forms agree quite well with the descriptions of S. corrugatus from north-west Spain by Rioja (1923) and from the Adriatic by Steninger (1910), except that the tubes of those forms were smooth. Caullery& Mesnil(1897), however, who gave the first adequate description of this species, found that their material (from near Cherbourg) had ridged tubes. The species is fairly close to S. ceylonicus Pillai (1960) and to other forms with which, indeed, it may be synonymous (Zibrowius, 1968). Distribution elsewhere : Adriatic, west Mediterranean, north-west Spain ; Roscoff (L’Hardy & Quikreux, 1964) ; Cherbourg ; Caribbean (Augener, 1936). Spirmbis (Janua) gnomonicus sp. nov. (Fig. 11) Dextral, white tube with three longitudinal ridges and obvious transverse growth lines. The mouth is round and the last whorl coils up on the previous ones. Diameter across coil 0.75-1 mm. Opercular plate flat or slightly convex with a very distinctive median crest projecting distally, like the gnomon of a sun-dial. S. unicornis Bailey (1968) and S.epichysis Bailey (19693) seem to be the only other known species of theJunua complex, which have the operculum bearing a distal process. Eggs are incubated below the opercular plate and there is then some calcareous thickening of the ampulla walls. A basal calcareous plate develops below the embryos. C FIGURE 11. Spirorbis (Janua)gnomonicussp. nov. A, Tube; B, operculum with developing brood chamber; C, operculum full of eggs; D, collar seta; E, seta of second or third segment; F, seta of third segment; G ,abdominal uncinus; H, thoracic uncinus;J, abdominal seta. SPIRORBINAE FROM THE AEGEAN SEA 377 Three thoracic segments. Collar setae are simple striated blades, with no trace of fins and without cross striations. On the second segment the setae have simple blades and on the third there is a mixture of some simple and other recurved, hooked blades. There are five abdominal segments, bearing geniculate setae with fine teeth. Found commonly on stones in samples from stations 1 (four samples), 2(3), 3(2), 4(2), 7(1). Depths from 5 to 40 m. Holotype and paratypes deposited in the British Museum (Nat. Hist.), Register Nos. 1968.91 and 92. Spirorbis (Janua) parvulus sp. nov. (Fig. 12) Dextral, white smooth tube. Last whorl coils up, so that the round mouth occupies an almost apical position over the umbilicus. Diameter across coil 0-75 mm. Slightly concave opercular plate with a thickened edge which forms the top of the brood chamber. There is a basal plate and no more than two embryos have ever been seen through the transparent walls of the chamber. 0 D FIGURE 12. Spirorbis (Janua)parvulussp. nov. A, Tube; B, operculum with two embryos; C, collar seta from convex side of the thorax; D, collar setafrom concaveside ;E, seta of second or third segment; F, thoracic uncinus; G, abdominal uncinus; H, abdominal seta. There are three thoracic segments. The collar setae are simple blades, cross-striated on the convex side of the body, simple on the concave. The setae of the second and third segments are simple blades. There are only three abdominal segments, each with uncini and a single geniculate, fine-toothed seta on each side. 378 JULIE H. BAILEY Found occasionally on stones in samples from Stations 1 (4 samples), 2(1), 4(1), 7( l),with no more than ten specimens in each collection. Depth 0-25 m. The shape ofthe tube is characteristic. It is only rarely that the tubes of S. corrugatus approach this shape. Some individuals of S. cormgatus, measuring less than 1mm in diameter across the coil, also bore embryos. These usually contained three or more embryos, however, and the bilobed eccentric talon, which is characteristic of juvenile S. corrugatus, could be seen clearly through the transparent walls of the brood chamber. Lack of a talon in S.parvuzus is highly characteristic. Holotype and paratypes deposited in the British Museum (Nat. Hist.), Register Nos 1968.89 and 90. DISTRIBUTION AND RELATIVE ABUNDANCE The distribution of species between collections is indicated in Table 1, in which the locations are arranged in order of depth, with the shallowest on the left. The main collecting site was Emborios bay (Station 1in Fig. l),which is very enclosed and shallow. At the mouth of the bay, on the south side, is a large cave, with a small wave-washed entrance, an average depth of 10 m and very reduced illumination. Outside the cave the bottom shelves to about 15 m depth. All this area is littered with stones and small boulders, very suitable for Spiror6is. Just south of the bay is a storm beach, of cobble stones. Station 2 was a rocky submarine peak, about 2.5 km south of Emborios and 100-200 m off shore. It rose from a sandy bottom, about 25 m deep, and came to within about 10 m of the surface. Station 3 was just south of Cape Mastikho and Station 4 south of the island of Venetiko. At both those sites the shore cliffs continue down almost vertically to about 30 m and then go on quite steeply to beyond diving range. Station 5, just south-east of an isolated rock, Mikro or Moula Petra, was also fairly steep and deep. Station 6 was off the small island of Aspro or Kokkina. Collections off the west point of Aspro went down to about 30 m, others from the south side were from a more shallow rocky bottom. Station 7 was around some rocks (Foradhas) which just break the surface about 600 m off shore. Station 8 was near Marmaron, off the north-west point of Nisos Margaritis. There were few Spirorbis from there, perhaps because those collections were rather general ones, which did not include many suitable substrata. A few dives were made off the north-west part of the main island, from Volissos to Point St. Nikolaos, but that coast is shallow and wave-washed, with a high sand table. The rocks and stones off shore are therefore too abraded to be suitable for Spirorbinae, which were not seen there, whilst the shore rocks were inaccessible, because of heavy surf. All those collections remote from Emborios involved overland journeys and coastal voyages in an inflatable speed boat. Table 1 indicates the distribution of species between various depths. Spirorbis corrugatus was the dominant species in shallow water, along with S. endournensis and S. cuneatus. Of the Janua complex, only S. gnomonicus seemed to favour the deeper locations. S.heteropoma was perhaps the most generally distributed, at all depths except the water’s edge. Marsipospira and most of the species of Pileolaria occurred predominantly at greater depths. They also occurred very commonly, however, in collections JULIE H. BAILEY 380 made from near the back of the cave (shown on right of Table 1).Their absence or scarcity in shallow water would therefore appear to be due to their shunning strong light. A small series of samples were scraped from cobble stones at measured depths off the beach just south of Emborios. The percentage contribution of each species to the Spirorbis population at each depth is indicated in Fig. 13. As in the bay, the species of the Janua complex were dominant in the shallow water samples, but Spirorbis endoumertSiS was not found off the beach, perhaps because it favours more sheltered environments. Scale A I B C ;j I D E F 0-5 G FIGURE 13. The distribution of Spirorbis on cobble stones at various depths off the beach south of Emborios. A, S. cormgatus; B,S. pagmtecheri; C, S. gnomonicus;D, S.parvulus; E,S. cuneatus F, S. koehleri; G, S. heteropoma. Scale indicates percentage of each species in the total population of Spirorbis at each depth sampled ( 0 , 2 , S , 10,12 m). The caique, a local fishing vessel from which scrapings were made by Mr A. R. D. Stebbing, was often tied alongside the Emborios jetty and was quite heavily fouled by Spirorbis and by Balanus amphitrite (the latter not being otherwise seen in Emborios Bay). Evidently Spirorbis may be readily transported by coastal vessels. ZOOGEOGRAPHICAL CONSIDERATIONS Of the species found on Chios two (S. cuneatus and S.pugenstechmi) extend to British waters (Gee, 1964) whilst another three (S.strktus, S.militaris and S. corrugatus) reach the Channel Islands and Roscoff. The pattern of distribution of the Chios species between subgenera, however, is very different from that on the Atlantic coast of Europe. Remarkably enough, the Atlantic coast pattern resembles that on the Galapagos (Bailey & Harris, 1968) rather than that on Chios, the latter being characterized by a very high proportion of species with opercular incubation. It is interesting to consider the nature of this pattern in some other of those few areas of the world from which the Spirorbinae have been studied. Table 2 shows the distribution of species between 15 such areas, including Chios. The Spirorbinae of the rest of the Mediterranean are dealt with by the authors named 382 JULIE H. BAILEY in the introduction. The record of S. borealis from Banyuls (Laubier & Paris, 1962) is perhaps questionable in the light of a later survey (Harris & Knight-Jones, 1964) which included the Banyuls area. The species of the western basin include most of those found at Chios, with the addition of S . (Spirorbis) infundibulum Harris & Knight-Jones, S. (Leudora)laevis (Quatrefages) and S . (Junua) pusilluides (Saint-Joseph). The Spirorbinae at Suez need further study. Outside the Mediterranean, the only other areas knownto have such a high proportion of opercular incubators are Ceylon (Pillai, 1960; de Silva, 1961, 1965) and the West Indies (Bailey, 1969 b). With the single exception of S. (Junua) pagenstecheri the Ceylon species are different from the Mediterranean ones, but some are obviously quite closely related and the pattern of representation in subgenera is very similar. In the Pacific only the eastern part is well known and the pattern there, revealed for Mexico by Rioja (1942,1962) and for the Vancouver area by Pixell (1912) and Potswald (1969, includes only between 40% and 50% of species incubating in the operculum. In western Europe there are records for north-west Spain (Rioja, 1923), Roscoff in north-west France (L’Hardy & QuiGvreux, 1964) ; south-west Britain (Gee, 1964; Harris, 1968b); Norway (Bergan, 1953) and the Arctic (Fauvel, 1909; Augener, 1913). Off Spain about half the species are opercular incubators, but off Roscoff this fraction falls to about a third. On analysis it seems that the Bay of Biscay acts as a barrier more for northern, littoral, tube-incubating forms t h n for the opercular incubators from the Mediterranean. In the South Atlantic two areas have been studied, Patagonia by Caullery & Mesnil (1897) and the tip of South Africa by Day (1961, 1963). S . adeonella Day (1963) was originally placed in Paralaeospira, but in Table 2 it is placed provisionally in Marsipospira, because of the form of the tube. This point needs further study, but it has no important bearing on the present discussion. Table 2 shows a clear tendency for forms with traces of a fourth thoracic segment (subgenera Paralaeospiru, Paradexiospira and Marsipuspira) to be favoured by low temperatures. It is only to be expected that tropical conditions would favour neotenous loss of this character, which develops gradually in older individuals (p. 369). High temperatures appear to favour opercular incubators, and might be expected to present special problems for the embryonic respiration of tube incubators, particularly where there is not much water movement. In barnacles embryonic development may be retarded or terminated by anoxia, at high temperatures (Crisp, 1959). Opercular incubation would presumably help respiration, but it seems likely that calm conditions would be necessary for this habit to be evolved. That conclusion may be drawn tentatively from two considerations. First, opercular incubators are less common off Galapagos and the west coast of Mexico, where the temperatures are high but the waters are presumably more disturbed by wave action than are those of the Mediterranean. Secondly, the broods of ill-adapted opercular incubators would be lost very readily in turbulent conditions, for in several species the opercular brood chambers are open proximally. It seems likely that the embryos are pushed into them by that route, the parents probably withdrawing into their tubes whilst spawning takes place (Bailey, 1969~).This problem, of how the eggs reach the brood chamber, is still not properly resolved, but the balance of opinion seems to favour SPIRORBINAE FROM THE AEGEAN SEA 383 their being pushed in basally, from the outside. The opercula of several Chios species look like inverted cups, which are more or less open basally or laterally (Figs 6 and 7), and the embryos of S . cluvus are readily displaced through the lateral opening, when material is being manipulated during laboratory study. This species would seem to be ill-adapted to retain its embryos, in turbulent conditions, and it may be significant that so far it has been found only in fairly deep water. One British opercular incubator, S. gsanulatus, is notably restricted to calm environments (Bailey, Nelson-Smith & Knight-Jones, 1967), although it seals its brood chamber effectively. Admittedly some others, like S. pugemtechmi, can live on wave-washed coasts, but it seems likely that turbulence would be an important hazard during the early evolution of opercular incubation, if the embryos are pushed into the brood chambers basally from the outside. One can thus imagine that the partially enclosed, semitropical Sea of Tethys may well have been the cradle of evolution for opercular incubators. Time has allowed more speciation of such forms in the area centred on the Mediterranean than in other regions. Fully adapted opercular incubators have subsequently reached latitudes where winds and tides are stronger, but have not yet been recorded from Patagonia. It should perhaps be noted that none of the three methods of brood retention found in modern Spirorbinae can be regarded credibly as ancestral to the others. It is more likely that each method (1, egg strings fixed to tube wall as in the subgenus Spirorbis; 2, thoracic pouch fured to a tentacular stalk as in the subgenus Mursipospiru; 3, opercular brooding as in the subgenus Pileoluriu) has been derived independently, from ancestral serpulids spawning into their tubes (Bailey, 1 9 6 9 ~ ) . The links between the Mediterranean, Ceylon and the West Indies, suggested by Table 2, involve relatively few species, which agrees with the remark of PCr&s(1967) that the zoogeographical links between the Mediterranean and the Indian Ocean involve genera and not species. The subgenera of Spirorbis could well be regarded as separate genera (see Bailey, 1 9 6 9 ~ )The . suggestionthat opercular incubators may have originated in the Tethys region does not, of course, require them to have lived in the Mediterranean area ever since. Ruggieri (1967) has suggested that the Tethys fauna was probably removed from the Mediterranean area by adverse conditions in the Miocene, after the connection with the Indian Ocean had been broken (though he admits the possibilities of survival in some basins). ACKNOWLEDGEMENTS I am indebted to the S.R.C. for a research studentship and to my academic supervisor Professor E. W. Knight- Jones for collecting the material, with the help of other members of the expedition. The Chios Committee, particularly Dr Philip Argenti and Mr D. J. Chandris, initiated and supported the project, in collaboration with the University College of Swansea. Dr Helmut Zibrowius, of Marseilles, gave me helpful information and Mr Tegwyn Harris, of Exeter, allowed me to use a prepublication copy of his invaluable key to the Spirorbinae of the world. REFERENCES AUGENER, H., 1913. Polychaeten von Franz-Joseph-Land 11. Zool. Anz., 41 : 253-273. AUGENER, H., 1936. Polychaeten aus den marinen Salinen von Bonaire und CuraGao. ZooZ.Jb. 67: 338-352. (Syst.). 384 JULIE H. BAILEY BAILEY,J. H., 1969a. Methods of brood protection as a basis for the reclassification of the Spirorbinae (Serpulidae). Zoo1.J. Linn. SOC.,48: 387-407. BAILEY,J. H., 1969b. Spirorbinae (Polychaetn: Serpulidae) from the West Indies. Stud. Fauna Curacao, in press. BAILEY,J. H. & HARRIS,M. P., 1968. 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