UNIVERSITY OF AMSTERDAM. Bundesrepublik Deutschland. Abstract. five representatives of this genus so far known. from the Mediterranean.

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1 Beaufortia INSTITUTE OF TAXONOMIC ZOOLOGY (ZOOLOGICAL MUSEUM) UNIVERSITY OF AMSTERDAM Vol. 41, no. 1 October 22, 1990 The genus Rhynchothorax (Pycnogonida) in the Mediterranean Sea Françoise Arnaud & Franz Krapp * Centre d'océanologie de Marseille, Station Marine d'endoume, Rue de la Batterie-des-Lions, F-1007 Marseille, France ** Zoologisches Forschungsinstitut und Museum Alexander Koenig, Adenauerallee , D-500 Bonn 1, Bundesrepublik Deutschland Abstract Ofthe five species of Rhynchothorax recorded from the Mediterranean, the description of Rh. alcicornis is completed with new material, and Rh. anophthalmus is synomymized with Rh. philopsammum. Created by Costa (1861) for a species collected on the Northern African coast (Tunisia or five reatives of this genus so far known from the Mediterranean. Eastern Algeria) that he named Rhynchothorax mediterraneaus, this genus comprises only minute-sized which were species long overlooked after Dohrn's record of the above species from In 1966 Capri (Italy). Stock (1966) Rhynchothorax alcicornis Krapp, 197 Rhynchothorax alcicornis Krapp, 197: 120, fig. 1; Child 1979: 67; Arnaud 1987: 47, 54; Arnaud described Rh. voxorinum from the vicinity of & Bamber 1987: 2. Banyuls-sur-Mer. Arnaud (1972) rediscovered New material examined: 2 O", NW Corsica, Ile Rousse, in calcareous algal concretions, Rh. mediterraneus in the Marseille area and described Rh. anophthalmus. Krapp (197) found Rh. alcicornis near Ischia (Italy). Finally, Rh , 1 to 1,5 m, (H. Zibrowius coll., diving). 1 C, Gulf of Foss-sur-Mer (about 0 km monnioti Arnaud, 1974, described from the W of Marseille), 11m, , in Posidonia Azores Is. (North Atlantic Ocean) was recorded west of Marseille (Arnaud, 1987). oceanica altered grounds; 4 O", same place, (A. Willsie coll., diving); 1 O* from Up to now, 15 species have been recorded Ischia, near the Institute, August-September from the World oceans and the paper, 1972, sponges, hydroids with sand (U. Schiecke in honour of our friend Jan H. Stock who has coll.). devoted a large part of his intensive scientific Male. Tegument finely granulated. Trunk activity to study the taxonomy of Pycnogonida sampled all over the world, intends to revise the Presence completely segmented. of middorsal tubercles: two on somites 1, 2,, one on 4th 1

2 Fig. 1: Rhynchothorax alcicornis, from Ischia, topotypical material: A dorsal view, B ventral view, C dorsal contour. Scale in all 1 mm. somite. Lateral processes less than separated by their diameter, with three multiple apophyses dorsal ornamentation, barrel-shaped, with dorsal antimere well developed and with triradiate on the distal distal extremities of processes 1 to mouth. Palps 5-segmented with the very typical. No individualized ocular tubercle, but two cephalic extensions (which are not to be considered as cheliphores) pointing forwards, with two clear behind them. Proboscis spots without 4th and 5th segments (fig. xxx). Cheliphores, contrary to the assertion in the original description, in which the two cephalic extensions were misinterpreted as such organs. Child 2

3 Fig. 2: Rhynchothorax alcicornis, same specimen as in fig. 1: A palp, B oviger, C distal articles of third leg (scale 0,1 mm); D a single special spine (scale 0,05 mm). (enlarged doubly)

(1979) clearly recognized this error and we After Costa (1861) who found Rh. mediter- agree that no adult Rhynchothorax has raneus on the Northern African coast (probably cheliphores.

4 (1979) clearly recognized this error and we After Costa (1861) who found Rh. mediter- agree that no adult Rhynchothorax has raneus on the Northern African coast (probably cheliphores. The legs are robust, with a short Tunisia or Eastern Algeria, where Italian conical point directed forwards on each first fishermen of these days had the monopoly of coxa. The male sexual orifice is situated on the large posterior dilatation of the second coxae of red coral collecting) "sulle rocce coralligene, tra fuchi, vermeti e serpole", Dohrn (1881) was the fourth legs. The femoral gland is a rather second author to record it from Capri at 90 m. inconspicuous ventral bulge bearing a small It was considered a rare species until Arnaud spine of the third legs only. Abdomen squaretipped, with two small distal corners (1972) discovered two specimens in a depth of 5 m among the infauna of a coralligenous algal individualized, and two round tubercles at habitat 20 km NW of Marseille. After that no midlength, dorsally. less than 49 individuals of both sexes have been Female. Unknown. counted in 18 samples taken between the Gulf Geographical distribution. The holotype found at Ischia (near Naples, Italy) by diving at 12 m on "coarse sand with rather much detritus" was accidentally partly damaged, but of Marseille and Cannes (French Riviera), Hyères Is., and NW Corsica (Bay of Calvi), mainly on detritic substrates. One record exists from the oriental Mediterranean Basin (Aegean another was discovered later in the same Sea, Antipsara I.) at "Calypso" station 801 locality. Two other locations should be added: The first is the SE zone of Fos-sur-Mer (0 km NW of Marseille) at Pointe Donnelle, 11 m, in (8 1 'N-25 1 'E, dredging m, On the Atlantic coast of Morocco (5 4'0"N 'W, 200 m, ) Posidonia oceanica beds. There, one O* was taken one O* was identified on dead branches of the in the four uppermost cm of a core made among Stylasteridae Errina aspera. roots of Posidonia. 4 more C were collected This species was also recorded from tropical between 4 and 8 cm under the surface of the sediment (sand accumulated the scales among localities as different as South Brasil, NW Madagascar and Aldabra Atoll (Seychelles Is.) of basal P. oceanica leaves). The second is from in the Indian Ocean, from 1 to 200 m. In the the NW coast of Corsica (Ile Rousse area), Mediterraneanit occurs mainly among calcareous algal concretions, at 1 to 1.50 on detritic bottoms (coralligenous algae*, substrates with m, in a sciaphilous habitat. small echinids or brachiopods, rock covered Rh. alcicornis seems to be strictly infeoded to with Laminarians) in relatively clean waters, sand, as it has never been collected mixed with from 5 to 120 m. other species of pycnogonids. Like Rh. philopsammum, it is devoid of burrowing organs and we must think that the size of sand particles and its porosity are two essential factors for finding these two species buried several cm below the Rhynchothorax monnioti Arnaud, 1974 Rhynchothorax monnioti Arnaud 1974: , figs. 1-5; Arnaud 1987: 48; Sanchez & Munilla surface. So far it is recorded from depths of : , fig. 4; Child 1988: 56. Only one and 12 m. new Ç specimen has been recorded in the Mediterranean Sea, in the vicinity of Marseille Rhynchothorax mediterraneus Costa, 1861 (Gulf of Fos-sur-Mer) at 15 m from coralligenous algae, from a rather sciaphilous Rhynchothorax mediterraneus Costa 1861: 8-9, pi. habitat. The 9 holotype came from the Azores 1; Dohrn 1881: ; pi. 17, figs. 1-9; Thompson 1909: 55, fig. 284; Arnaud 1972: 408 (key), 409; Krapp 197: 121 (key); Arnaud 1976: 70; Arnaud 1987: 47-48; Arnaud & Bamber 1987: 2, 57, 69; Child 1988: 56. * In Arnaud & Bamber (1987: 2), at the end of chapter "Tropism", instead of R. alcicornis from coralligenous algae in the same area" should be read R. mediterraneus from coralligenous..." 4

5 Table 1. Tabular key for differentiating the five mediterranean species of Rhynchothorax Oculated species Blind species mediterraneus monnioti voxorinum alcicornis philopsammum Proboscis type* C 2 E" G' 2 B 2 E"' C 1 B 1 dorsal antimere dorsal ornamentation 1 median horn at 1 tubercle anterior light bosses the proximal third to midlength Ocular tubercle with anterior hori- large, conical, zontal projection anteriorly bent low, rounded Eyes 4 pigmented 4 pigmented 4 pigmented 2 round spots Post ocular tubercles Palp segments 5 (rd with a 6(1, & 4 with 6 (1st with a lateral 5 (5th bifid 4 (rd with a spur) a spur) strong spur) distally) strong dorsal tubercle) Lateral cephalic spurs Trunk sutures 2 2 Middorsal tubercles columnar conical strong, granular 5 low, rounded Spurs on lat. processes 1 dorsal, poste- 1 strong posterior, long, multi- 1 anterior and 1 1st and on strong riorly with short setae tuberculated posterior, short 2nd lateral processes Tegument shagreened with small with small with numerous shagreened granulations granulations granules Legs slender with some slender, smooth slender with some strong with nu- relatively strong, granulations setae merous granules with few setae Auxiliary claws about half the half of the main thirds of the two main claw claw main claw Sexual orifice in cr long spur on rd small ventral swel- small spur on 2nd large posterior coxae of rd legs ling on 2nd coxae coxae of 4th legs swelling on 2nd of rd legs coxae of rd legs Segments of the O* oviger cr oviger spines simple denticulated denticulated denticulated Segments of the 9 oviger reduced to a small (with simple cone spines) + as defined by Fry & Hedgpeth (1969). Is. (Atlantic Ocean) at 7 16'54"N-24 47'W, Charcot" station m, "Jean 207, on peculiarities. Only the O* sex is known from the surface of a sponge encrusting the inferior face gravel, shells and stones. Sanchez & Munilla of a stone at Cape Creus (NE Spain), -18 m (1987) have identified another Ç from the SE of deep. It is a very tiny pycnogonid measuring Tenerife at (Canary Is.) 62 m on calcareous algal bottom, and Child (1988) recognized 1.1 mm in total length. This species confirms the negative Zilberberg's Brazilian specimen no. 2 as a phototropism also exhibited by the four other juvenile of Rh. monnioti. So the male sex Mediterranean relatives, which have cryptic remains todate. tendencies, living in crevices or being endopsammic as Rh. alcicornis and philopsammum, and Rhynchothorax voxorinum Stock, 1966 even lacking any burrowing organ. We have tabulated the main characters permitting the Rhynchothorax voxorinum Stock 1966: , easy identification of the five Mediterranean fig. ; Arnaud 1987: 48. reatives so far recorded, hoping that the No other specimen having been discovered lack of informations about one sex of a few since its description, despite our careful searches, nothing could be added to its life species will be filled in the coming years (table!) 5

Rhynchothorax philopsammum Hedgpeth, 1951 RE-DEFINITION OF THE FAMILY RHYNCHOTHORACIDAE THOMPSON, 1909 1951: Rhynchothorax philopsammum Hedgpeth 111-115, ; Stock 1966: 415 (key).

6 Rhynchothorax philopsammum Hedgpeth, 1951 RE-DEFINITION OF THE FAMILY RHYNCHOTHORACIDAE THOMPSON, : Rhynchothorax philopsammum Hedgpeth , ; Stock 1966: 415 (key). Zago 1970: (key); Arnaud 1972: 408 (key); Krapp 197: 121 (key); Clark 1976: 295 (key); Child 1979: 67, 72, fig. 24h; Stock 1986: 700. Arnaud Rhynchothorax anophthalmus 1972: , figs 1-7; Arnaud 1974: , figs 6-7; Child 1979: 67, fig. 24i; Arnaud 1987: 47, 54; Arnaud & Bamber 1987: 8, 2, 69. Already in the original description the strong morphological similarities of Rh. anophthalmus with philopsammum were pointed out. Eleven new individuals from the Azores Is. dredged at of 77 a m on a depth bottom composed of gravel, shelly sand with calcareous algae on and (8 4'N 'W) three The familial affiliation of the genus Rhynchothorax has long been uncertain, being variously the placed among Ammotheidae or the Colossendeidae. Thompson (1909) created the family Rhynchothoracidae for the single genus Rhynchothorax, at a time when only two species were known: Rh. mediterraneus Costa, 1861 from the Mediterranean Sea and Rh. australis Hodgson, 1902 from the Antarctic. Child (1979) discussed the opportunity of removing this genus from the "old" families and was tempted to adopt Rhynchothoracidae, as it was already accepted by Arnaud & Bamber (1987). We the propose following characters for this family: minute-sized body (total length usually less than 2 mm), trunk with 2 or sutures, very to re- more Mediterranean examples lead us examine the two species comparatively. The integument is Absence of dorsal ornamentation, of an ocular finely granulated. tubercle, and of have been cheliphores which misinterpreted until Child (1979) demonstrated that these organs were in fact cephalic extensions as for alcicornis. The palps are only 4- The males segmented. exhibit stronger lateral apophyses and the 2nd coxae of the rd legs bear a posterior conical sexual gland with sexual orifice. The Mediterranean specimens were found the invertebrates settled after 6 and 12 among months on immersed artificial reefs in the Gulf of Marseille at 4 m on coralligenous bottom, and in the dark central part of these reefs. The 4 9 from California were collected "from coarse sand some five or six inches below the surface" (Hedgpeth 1951). We have no doubt that Rh. anophthalmus is of Rh. ajunior synonym short legs, absence of in cheliphores adults (vestigial in juvenile stages of a few species), palps 4- to 6-segmented. Ovigers -segmented (Cf) or 9-segmented (<?) Strigilis with simple or denticulated spines, the distal segment being typically enlarged with a terminal claw forming a subchela. This very distinctive family of tiny pycnogonids lives cryptic in biodetritic or psammophilous habitats, including even endopsammic forms. It possesses reatives in and cold Antarctic temperate, tropical waters. REFERENCES ARNAUD, F., Un nouveau pycnogonide de Méditerranée nord-occidentale: Rhynchothorax anophthalmus n. sp. et redécouverte de Rhynchothorax mediterraneus Costa, Téthys, (2) ("1971): philopsammum., Pycnogonides récoltés aux Açores par les The geographical distribution includes now campagnes 1969 et Biaçores Bull. zool. Mus. the Pacific Ocean (coastal California, shores of the Gulf of Tehuantepec and Bora Bora I.), Atlantic Ocean (Azores Is.), and the NW part Univ Amsterdam, (21):, Sur quelques pycnogonides de Turquie et de la mer Egée(Méditerranée orientale). Acta ecológica Iranica, 1: of the Mediterranean (Marseille area)., Les pycnogonides (Chelicerata) de Méditer- 6

7 , - ranée: Distribution écogique, bathymétrique et HODGSON, T. V., Pycnogonida. - "Discovery" biogéographie. Mésogée (Bull. Mus. Hist. nat. Marseille), 47: national Antarctic Expedition (Zoology), (1): 1-71, pis. ARNAUD, F. & R. N. BAMBER, KRAPP, F., 197. A fourth mediterranean Rhynchothorax The biology of Pycnogonida. Advances mar. Biol., 24: and remarks on the genus (Pycnogonida). Bull. zool. CHILD, C. A., Shallow-water Pycnogonida of the Mus. Univ. Amsterdam, (17): Isthmus of Panama and the coasts of Middle MÜLLER, H.-G., Shallow-water Pycnogonida from America. Smithsonian Contr. Zool., 29: coral reefs at Moorea, Society Islands, with descrip-, Pycnogonida from Carrie Bow Cay, Belize. tion of Rhynchothorax tiahurensis n. sp. Bonner Smithsonian Contr. mar. Sei., 12: zool. Beitr., 40(2): Pycnogonida from Aldabra Atoll. Bull. biol. Soc. Washington, 8: SANCHEZ, E. L. & T. MUNILLA, Picnogónidos (Pycnogonida) de la comunidad de Dendrophyllia ramea COSTA, O. G., Microdoride mediterranei o descri- en el Sureste de Tenerife. Vieraea, 17: zione de' poco ben conosciuti od affatto ignoti viventi &, 1989: Estudio ecológico de los primeros Pic- minuti e microscopici. Con tredici tavole: XVIII + nogonidos litorales de las islas Canarias. Cah. Biol. 80 pp. (Napoli, Stamperia dell'iride). Mar., 0: DOHRN, A., Die Pantopoden des Golfes von Neapel STOCK, J. H., Sur quelques pycnogonides de la und der angrenzenden Meeresabschnitte. Fauna und Flora des Golfes von Neapel und der angranzenden région de Banyuls (e note). Vie Milieu, 17(1B): FRY, Meeresabschnitte, : W. G. & J. W. HEDOPETH, The fauna of the THOMPSON, W. d'arcy, Pycnogonida. In: S. F. Harmer & B. E. Shipley (eds.): The Cambridge Ross Sea. Part 7. Pycnogonida, 1: Colossendeidae, Natural History, 4: (Macmillan, London). Pycnogonidae, Endeidae, Ammotheidae. (New Zealand Océanographie Institute Memoir No. 49). New Zealand Dept. Sei. Ind. Res. Bull., 198: HEDGPETH, J. W., Pycnogonids from Dillon Beach and vicinity, California, with descriptions of two new species. WasmanJ. Biol., 9(1): Received: December 15, 1989 Institute of Taxonomic Zoology (Zoologisch Museum), University of Amsterdam, P.O.Box 4766, 09 AT Amsterdam, the Netherlands 7

Bulletin Zoologisch Museum

Bulletin Zoologisch Museum 23 S3 VAN AMSTERDAM Vol. 3 no. 17 23-X-1973 A fourth Mediterranean Rhynchothorax and remarks on the genus (Pycnogonida) Franz Krapp Abstract pycnogonids known to share this unusual