Priapulus atlantisi and Priapulus profundus. Two new species of Priapulids from bathyal and abyssal depths of the North Atlantic

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P r i a p u l u s atlangisi and P r i a p u l u s p r o f u n d u s . Two new species of Priapulids from bathyal and abyssal depths of the North Atlantic HOWARD L. SANDERS and ROBERT R. HESSLER*

(Received 2 April 1962) A RECENT paper by MURINA and STAROBOGATOV (1961) recognizes six species belonging to the class Priapuloidea. Our present qualitativeand quantitativesurvey of the benthonic fauna along a transect between southern N e w England and Bermuda has yielded two new species of priapulids representing the seventh and eighth known members of this class, Because this is the firstclear record of totally hathyal and abyssal priapulid species (see MUR1NAand STAROBOGATOV, 1961, regarding Priapulus tuberculatospinosus abyssorum MENZlF.S, 1959), we feel that this note is particularly appropriate for

Deep-Sea Research. P R I A P U L U S A T L A N T I S I N. SP.

Introvert ovoid, transparent, large, comprising in most specimens 53-63 per cent of total length excluding caudal appendage (see Fxos. IA and 3). Approximately thirty circular muscle bands discernibie. Twenty-five longitudinal rows of minute spines alternate with 25 bands of longitudinal muscles along rrmjor axis of introvert. Two ventral rows of spines parallel and closely opposed to white opaque nerve cord which terminates anteriorly at neural zone. Spines on longitudinal rows bluntly pointed and composed of 16 clusters or less. Each cluster made up of six spines; first (most anterior) spine twice the length of second which is slightly longer than third. Remaining three spines merely elevated protuberances (FIG. IB). Number of spines in more posterior clusters reduced. Collar region containing nerve ring with well-developed papillae m/l~h ~irger than spines on longitudinal row 6 (FIG. lA). Trunk somewhat translucent in some specimens; usually smaller than introvert; form variable, may be pear-shaped, barre!-shaped or cylindrical (Fzo. 5D) with circular ridge-like swelling (not always obvious) near posterior end. Nerve cord present as opaque, white band on ventral surface. Approximately 50 transver~ annulatious present. Longitudinal furrows readily detectable in some specimens (FIo. IA). Posterior margin truncated. No warts or small papillae evident either on posterior extremity or elsewhere on trunk. Caudalappendage paired, composed of two annulated vascular stalks bearing as many as ten nodes depending on length. Each node gives rise to a quartet of bladder-like vesicles, minute on base of stalk but successively lar~r distally (Fzo. IA); tiny papillae or spines on surface of vesicles(FJo. IC). Mouth with ci~umoral teeth arranged in rows; the first 5 or 6 rows pentagonal (FIQ. ID). Teeth of first pentagon (closest to mouth) in form of small, shallow ridge with 8-10 spines. Teeth of second pentagon large, broadly V-shaped distally, smoothly rounded proximally; with 16--19spines. Teeth of third pentagon ~ t , with strongly developed long medial spine and 14-18 lateral spines extending to lateral edge of concave distal margin. Teeth of pentagon 4 similar to pentagon 3 but smaller in size; lateral spines extend further distally on median spine than in pentagon 3. Teeth of pentagon 5 smaller in size but similar in shape to fourth; with 18-22 lateral spines. Teeth of row 6 smaller than previous row; with 12-16 lateral spines confined to lateral margin of median spine; lateral edge of distal margin smoothly rounded. Teeth of row 7 like sixth but larger; with 10 lateral spines. Eighth row like seventh but smaller; ninth row smaller than eighth. Row ten still smaller and roughly triangular in outline. Priapulus atlantisi differs from all other known species by its proportionately larger introvert (FIo. 3), the large number of lateral spines on the circumoral teeth (Flo. 4), and the morphology of the caudal appendage (F]os. lA and IC; see MtmlNAand STAROBOGATOV,1961, FIo. 7). The lengths of 21 specimens, including the caudal appendages, ranged from 1"13 to 7.70 mm. On May 24, 1961 four specimens ofPriapulus atlanti$iwere collected from a sample taken aboard the R.V. Atlantis from a depth of 1500 metres on the continental slope south of New England (station F; lat. 39°4TN, long. 70°45'W). On the same day, 26 additional individuals of the same species, *'Contribution No. 1268 from the Woods Hole Oceanographic Institution. This research was supported by National Science Foundation Grant G°15638.

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Shorter Communications PRIAPULUS

PROFUNDUS

N. SP.

Introvert ovoid, transparent, comprising about 42 per cent of total length excluding caudal appen¢h]ge (FIGs. 2A and 3). Approximately forty circular muscle bands discernible. Twenty-five longitudinal rows of small spines alternate with 25 bands of longitudinal muscles along major axis of introvert. Spines on longitudinal rows bluntly pointed and arranged in about 11 clusters. Four spines present in each of five anterior clusters (Fro. 2B); three in sixth cluster; two in seventh; one or two in eighth; single spine on ninth through eleventh. First (most anterior) spine about one-third longer than s e ~ n d ; remaining two spines progressively smaller. Collar with papillae not much larger than spines on longitudinal rows (Fro. 2A).

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Fxo. 3. Showing the percentage of introvert length to total length excluding caudal appendage in the various priapulid species. The data for Haticryptus spinulosus and Priapulus bicaudatus are derived from the figures of THEEL, 1906: for Priapulus tuberculatogpinosus tuberculatospinosus, BAIRD, ! 868 and DE GUERNE,1891 ; Priapulus horridus, TXEEL, 191 I ; Priapulus tuberculatospinosu$ abyssorum, MENZlES, 1959; Priapulus augtralis, DE GUEaNE, 1891; Priapulus caudatus, our measurements of specimens from Tomales Bay, California; Priapulus atlantisi and Priapulus profundus, present paper.

Trunk light tan and somewhat translucent, appreciably longer than introvert, cylindrical in shape, with well-developed swelling near posterior end. Nerve cord present as narrow, opaque, white longitudinal band on ventral surface. Approximately 50 well-developed transverse annulations present; swelling near posterior end single annulus appreciably enlarged, about five times as wide as other annuli. Girdle of about 25 evenly spaced warts present on enlarged annulus on circular ridge (Fio. 2C). Region posterior to enlarged annulus entirely covered with small papillae giving appearance of honeycomb. Small papillae irregularly dispersed elsewhere on trunk. Longitudinal furrows not discernible. Posterior margin acutely rounded. Caudal appendage single elongate tube-like vesicle divided by three constrictions into four segments which become progressively longer distally. Entire structure covered with minute bristles or spines (FIG. 2C). Mouth with circumoral teeth arranged in rows; the first 5 or 6 rows pentagonal (Flo. 2D). Teeth of first pentagon (closest to mouth) in form of slightly convex ridge with about 12 small spines on median portion. Teeth of second pentagon asymmetrical with 5 spines on one side of largest spine and single spine on other. Teeth of pentagon 3 shallow, with broadly V-shaped distal edge bearing 9 spines across entire margin; median spine no longer than lateral spines. Teeth of pentagon 4 smoothly rounded proximally, with distal edge more acutely V-shaped than of previous pentagon ; IT~dlan spine wcll-deve]op(:d; 8 intern] spines extend along entire distal margin, becoming progressively smaller laterally. Teeth of pentagon 5 l a r i a t , similar in shape to teeth of pentagon 4 but

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with relatively longer and more robust median spine and with I0 lateralspines. Teeth of row 6 much smaller, rounded; with well-developed median spine and 6 lateral spines. Teeth of row 7 rounded; median spine small, weakly developed; with 8 lateral spines restricted to apex of tooth. Teeth of row 8 like previous row but smaller and with only 4 lateral spines. Pr/opu/m proft~dw differs from all other known species by the enlarged posterior annulus with a row of warts (Flo. 2C) and the morphology of the caudal appendage (Fio. 2C; see MUR]NAand STAItOaOOATOV,1961, FIO. 7). The lengths of the three specimens ofP. profundus are 4.6, 4.3, and 2.6 nun, including the caudal appendage. Two specimene of Prlapulusprofundus were collected on October 2, !961 from a sample taken under the Gnlf Stream at a depth of 4483 metres (station JJ; lat. 37°27~N,long. 68°41'W). A third specimen was collected by R.S. Scheltema on August 9, 1961 from 3800 metres (station II; lat. 38°00"N, long. 69°31'W).

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Fro. 4. Showing the range in number of lateral spines on single pentagonal tooth of various prlapulid species. The data for Priapulus caudatus, Priapulus bicaudatusandPriapulus tuberculatospinosus tuberculatospinosus taken from THEFt, 1911; Priapulus australis, DE GUER~, 1891; Priapulus tuberculatospinosus abyssorum, ME'NzI~, 1959; Priapulus profundu$ and Priapulua atlantisi, present paper.

THE L O R I C A T E

LARVA

OF PRIAPULUS

ATLANTISI

W e have assumed that the nine Ioricatelarvae collectedat stationO belong to the species,Priapulus atlantisi, because it was the only adult priapulid found at this station. These larvae differed little in size, the lorica or cuticularize~ encasernent varying only from 0"82 to 1"02 nun in length. Lorica somewhat vase-shaped, composed of several transparent plates (F[o. 5A). Dorsal and ventral plates large. Interposed between them on each lateral surface are three narrow lateral plates. Each plate separated from neighbour by thin furrow or membrane. Two pairs of tactile spines arise near posterior end of lorica from dorsal and ventral mar~us of middle lateral plate (FIG. 5A). Along anterior margin of dorsal plate is small, narrow, crescent-shaped plate; two minute, somewhat triangular plates are at its anterolateral edges, and a minute narrow plate, rounded laterally, is at its anteromedial margin. An identical set of plates are found anterior to the ventral plate. All of the plates anterior to the dorsal and ventral plates are light tan and have roughened punctate appearance. Anterior to each lateral plate is minute narrow anterior lateral plate (Fro. 5C). Introvert rounded in shape with about twenty-five rows of posteriorly directed spines alternating with twenty-five rows of longitudinal muscles. Eight large papillae of spines form circle on introvert posterior to mouth (Fro. 513). Trunk elongate, smoothly rounded with posterior end prolonged into fleshy protuberance and

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attached to lorica by funnel-shaped muscle. Arising from surface of ~runk are numerous fine spines (Flo. 5A). The loricate larva of Priapulu~ atlantisi differs from two other described loricate larvae, Priapulus caudatus (LAI~o, 1948) and Halicryptu8 spinulosu$ (H~MI~ARS'r~, 19| 5) by ira large number of plates~ 22 in P. atlantisi, 10 in P. caudotus, 8 in 14. spinulosus--and the presence of nmnerous fine spines on

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FIG. 5. A, loricate larva of Priapulus atlantisi. B, introvert of loricate larva. C, anterolateral view of lorica showing small anteriOr lateral plates. D, Priapulusatlantisi adult, showing variable form of trunk.

the trunk. The larger total number of plates in P. atlantisi is accounted for by the numerous accessory anterior plates. The small foot present on the posterior end of the larva ofP. caudatus (L^N¢3, 1939) is absent in P. atlantisi. REFERENCES

BAIRD, W. 0868) Monograph of the species of worms belonging to the subclass Gephyrea; with a notice of such species as are contained in the collection of the British Museum. Proc. Zool. Soc. 1868, 76-114. DE GUERNE,J. (1891) Priapulides. Mission scientifique du Cap Horn 1882-1883, 6, 1-20. HAMMARSTEN,O. D. (1915) Zur Entwicklunpge~h~hte von Halicrypt~ spinulosus (yon Siebold). Z. f. Wiss. Zooi. 112, 527-571. LJ~'qo, K. (1939) Uber die Entwicklung von Priapulus caudatus Lam. Kungl. Fysiogr. Sdllsk. Lund Fitrhandi. 9 (7), 80-87. LAN6, K. (1948) On the morphology of the larva of Priapulus caudatus Lain. Ark. f. Zool. 41A (9), 1-8. MENZmS, R. J. (1959) Priapulus abyssorum, new species, the first abyssal priapulid. Nature Lond. 184, 1585-1586. MugrNA, V. V. and STAROSOOATOV,J. I. (1961) Classification and zoogeography of Priapuloidea. Trud. Inst. Okeanol. 46, 179-200. (In Russian.) THEgL, l-IJ. (1906) Northern and Arctic invertebrates in the collection of the Swedish State Museum. II. Priapulids, Echiurids etc. Kungl. Sv. Vet.-Akad. Handl. 40 (4), 1,-28. TH~L, HJ. (1911) Priapulids and Sipunculids dredged by the Swedish Antarctic Expedition 1901-1903 and the phenomenon of bipolarity. Kungl. Sv. Vet.-Akad. HandL 47 (1~, 1-36.