Italian Journal of Zoology

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Marine gastrotrichs from the Tremiti archipelago in the southern Adriatic Sea, with the description of two new species of Urodasys Fregni Elena , Maria Grazia Faienza , Susanna De Zio Grimaldi , Paolo Tongiorgi & Maria Balsamo To cite this article: Fregni Elena , Maria Grazia Faienza , Susanna De Zio Grimaldi , Paolo Tongiorgi & Maria Balsamo (1999) Marine gastrotrichs from the Tremiti archipelago in the southern Adriatic Sea, with the description of two new species of Urodasys , Italian Journal of Zoology, 66:2, 183-194, DOI: 10.1080/11250009909356254 To link to this article: http://dx.doi.org/10.1080/11250009909356254

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Ital. J. Zool., 66. 183-194 (1999)

Marine gastrotrichs from the Tremiti Archipelago in the southern Adriatic Sea, with the description of two new species of Urodasys FREGNI ELENA Dipartimento di Biologia animale, Università di Modena e Reggio Emilia, via Università 4, 1-41100 Modena (Italy)

MARIA GRAZIA FAIENZA SUSANNA DE ZIO GRIMALDI Dipartimento di Zoologia, Università di Bari, via Orabona 4, 1-70125 Bari (Italy)

PAOLO TONGIORGI Dipartimento di Biologia animale, Università di Modena e Reggio Emilia, via Università 4, 1-41100 Modena (Italy)

MARIA BALSAMO Istituto di Scienze Morfologiche, Università di Urbino, via Oddi 21, 1-61029 Urbino (Italy)

ABSTRACT Twenty-four macrodasyid and thirteen chaetonotid species of marine Gastrotricha are reported. Two of these species - Urodasys apuliensis and U. bucinastylis - are new, while the macrodasyid genus Crasiella is reported for the first time in Italy and the Mediterranean basin. Samples were taken at depths varying from 1 to 34 metres. Altogether, the number of species found was relatively high and comparable with the range of fauna found on the major Italian islands. A possible evolution of the reproductive system in the genus Urodasys is briefly discussed.

INTRODUCTION In order to complete the faunistic and zoo-geographic picture of the marine species of the phylum Gastrotricha, our study has recently focused on insular fauna. A number of small and very small islands of different origin and morphology with coastal sediments of an extremely various nature are scattered around the Italian coasts. Even the latitudes of the islands vary considerably: the most northern island is Palmaria (La Spezia), which lies between the Ligurian and the Tyrrhenian Seas, while the furthest south is Lampedusa (Pelagian Archipelago), in the middle of the Sicilian Channel. The only archipelago in the Adriatic Sea is the Tremiti Archipelago, which faces the Apulian coast and the Gargano headland at the boundary between the central and lower Adriatic. The archipelago has a total area of about 3 km2 and comprises three small islands of friable, calcareous rocks - San Domino, San Nicola and Caprara (or Capraia) - and the clayey rock Cretaccio. A fourth island, Pianosa, lies 12 miles further east. The coasts of the islands are rocky and steep, as is the northern coast of Pianosa. The only sandy beach is on the east coast of San Domino, while there are several other very small beaches at Caprara. The islands are surrounded by almost exclusively rocky sea bottoms, but there are some sandy or gravel areas at the bottom of submarine depressions and gorges. As the various basins composing the Mediterranean Sea are relatively isolated, the hydrological conditions around the islands and the archipelagos vary greatly, thus influencing the bio-diversity of the local faunas in different ways. The gastrotrich fauna of the major Italian islands, Sicily and Sardinia, was studied by Balsamo et al. (1995, 1996), while that of some of the minor islands was addressed in a series of surveys covering Elba, Giglio, Capraia (Balsamo et al, 1992; Todaro et al, 1992) and Montecristo (Balsamo et al, 1994) in the Tuscan Archipelago; Ponza in the Pontine Archipelago (Todaro, 1992), Ischia and Procida in the Campania Archipelago (Hummon et al, 1996, 1998), and Lampedusa in the Pelagie Islands (Fregni, 1995). MATERIALS AND METHODS Collecting time and sites

KEY WORDS: Gastrotricha - Marine meiofauna - Mediterranean fauna - Tremiti Archipelago - Italian fauna. ACKNOWLEDGEMENTS We wish to thank Mr Lucio Rositani (Laboratory of Marine Biology, Bari) and Prof. Angelo Tursi for their collaboration in collecting samples. This research was supported by grants from the Italian Ministry of Higher Education and Scientific and Technological Research (within the MURST 40% research programme 'Popolamento animale del Mediterraneo Occidentale') to PT. (Received 20 February 1999 - Accepted 24 April 1999)

The collecting trips were carried out in May 1998. Samples of sediment were collected from five stations on San Domino and from three stations on San Nicola and Capraia (Fig. 1). Altogether, samples were taken from twenty-three different sites, the geomorphological characteristics and the depth of each collecting site (depths from lm to 34 m) are specified below. Only at one site was the sample collected from the water-line (littoral sample). Some other samples (July 1997 and March 1998) were given to us for study by Prof. Angelo Tursi of the University of Bari. Caprara Island Station 1 (Cala dei Turchi): 25/05/98, 12 m depth (mediumcoarse sand from a depression among the rocks), 28 m depth (medium-fine sand), 34 m depth (medium-fine sand with mud).

F. ELENA, M. G. FAIENZA, S. DE ZIO GRIMALDI, P. TONGIORGI, M. BALSAMO

184

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by Todaro (1992). An alternative extraction technique was used to study fixed specimens. This involved a hypotonic shock of the sample by washing the sand with fresh water, followed by rapid centrifugation of the percolating fluid, filtering of the supernatant through a 42 um mesh sieve, and fixing in 10% formalin. Very fine sediments were treated with Ludox AM (Dupont), a solution of silica in formalin with a specific weight less than that of the sediment, at a ratio of 1:3. After two centrifugations, the first for 5 min at low speed (700 rev/min) and the second for 10-15 min at high speed (1000 rev/min), the supernatant was filtered through a 42 um-mesh sieve, then washed in sea water and finally fixed in 5% neutralised formalin. Specimens were mounted on slides in Hoyer's liquid (modified according to Higgins, 1983), or slowly dehydrated in a mixture of ethanol and glycerine (95:5) and mounted in glycerine or glycerinated Kaiser gelatine (Merck) (Higgins & Thiel, 1993). Morphometric parameters, which are the basis of the taxonomy of a species, are given for those species new to Italian fauna. For the others, morphology is indicated only where it contrasts data in the literature. The location of the morphological characteristics along the body of the new species of the genus Urodasys are given in percentage units (U) of the total body length measured from anterior to posterior, but excluding the tail.

RESULTS

Systemic account Altogether, thirty-seven gastrotrich species (twentyfour Macrodasyida and thirteen Chaetonotida) were collected from seventeen of the twenty-three sites (Table I). The macrodasyids belonged to twelve genera (AcanthoStation 2 (Secca delle Vedove, in a cave): 25/05/98, 24 m depth dasys, Crasiella, Dactylopodola, Lepidodasys, Macro(medium-coarse sand, with coral fragments and mud). dasys, Mesoddsys, Paraturbanella, Platydasys, TetranStation 3: 26/05/98, 7 m depth (medium-coarse sand at the chyroderma, Thaumastoderma, Turbanella, Urodasys), edge of a sea-grass bed), 10 m depth (medium sand), l l m depth (medium sand with pebbles, from the bottom of pits among the and the chetonotids to five genera (Aspidiophorus, rocks). Chaetonotus, Draculiciteria, Heterolepidoderma, Xenotrichuld). One species could be identified only at a San Nicola Island generic level because of the insufficient number of Station 4: 25/05/98, 18 m depth (medium, coralline sand). specimens. Two macrodasyid species of the genus UroStation 5: 26/05/98, 20 m depth (medium-fine sand with mud), 26 m depth (medium-fine sand with mud). dasys are new to science, and the -macrodasyid genus Station 6: 25/03/98, 9 m depth (coarse sand from a relatively Crasiella is reported for the first time in Italy and the flat and open area among sea-grass). Mediterranean basin. Photographic negatives of holotypes and paratypes are deposited at the Museum CiviSan Domino Island Station 7 (locality I Pagliai): 11/07/97, 10 m depth (medium co di Storia Naturale, Verona (Italy)/ sand and organogenic detritus among the rocks). For each species, the name of the island, the number Station 8 (near Cala Spino): 25/03/98, 12 m depth (medium of the collecting station and the depth of the sampling sand from sea-grass with high and dense leaf covering); 26/05/98, site are given. 30 m depth (medium sand). Fig. 1 - Location of sampling sites: isobars are indicated by broken lines and Posidonia beds by the dotted areas.

Station 9 (Cala delle Arene, a beach sheltered by surrounding rocks): 26/05/98, littoral sample (fine sand and organogenic detritus), 1 m depth (medium sand), 2 m depth (medium sand). Station 10 (Grotta del Sale, near the cave): 25/03/98, 5 m depth (medium-coarse sand); 11/07/97, 10 m depth (coarse sand from the unevenness of the cave wall, substrate with flat pebbles and encrusted coralline algae); 11/07/97, 20 m depth (coarse sand with organogenic detritus, small pebbles with encrusted coralline algae). Station 11 (Grotta delle Viole, inside and outside the cave): 26/05/98, 7 m depth (medium-coarse sand at the centre of the cave from small pits among the rocks), 9 m depth (medium sand rich in organic matter at the cave mouth), 18 m depth (mediumcoarse sand outside the cave). Methods The samples of sediments were collected by SCUBA diving. Specimens were studied in vivo following the methods described

Order Macrodasyida Rao & Clausen, 1970 Family DACTYLOPODOLIDAE Strand, 1929 Genus Dactylopodola Strand, 1929

Dactylopodola typhle (Remane, 1927) Caprara, station 3 , 7 m depth.

Widespread along the coasts of Liguria, Tuscany, Latium, Campania, Apulia and Friuli, D. typhle has also been found on the islands of Capraia and Elba (Tuscan

MARINE GBASTROTRICHS FROM THE TREMITI ARCHIPELAGO

185

TABLE I - Macrodasyida and Chaetonotida at the Tremiti Archipelago.

Island

Caprara

Stations

1

Depth at the cotecting site (m)

San Nicola

2

3

12

28

34

24

7

-

-

-

-

•

4

10

11

San Domino

5

18

6

20

28

S

10

12

30

ittoral

1

2

5

10

20

7

9

18

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.

-

MACRODASYIDA DACTYUOPODOLIDAE Dactylopodola D. typhle LEPIDODASYIDAE

Lepidodasys L. martini Mesodasys M. adenotubulatus M. ischiensis M. laticaudatus

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MACRODASYIDAE

Macrodasys M.caudatus M.gerlachi M. thuscus Urodasys U. apuliensis n. sp. U. bucinastylis n. sp. U. viviparus PLANODASYIDAE Crasiella C. sp. THAUMASTODERMAT1DAE Acanthodasys A. aculeatus Platydasys P. sp. Tetranchyroderma

T. heterotubulatum T. hypopsilancrum T. pofypodlum T. s a r d u m T. thysanogaster T. thysanophorum Thaumastoderma T.heideri TURBANELLIDAE Paraturbanella P.dohmi P.pallida Turbanelta

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T. subterranea Total macrodasylds 24

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CHAETONOTIDA CHAETONOTIDAE

Aspidiophorus A. mediterraneus A. parameditBrraneus Chaetonotus C. (E.) aegilonensis C. (B.) apechochaetus C. (E.) siciliensis C. (S.) atrox C. (S.) dispar C. (S.) hilarus C. (S.) luporinii C. (S.) neptuni Haterolepidoderma H. loricatum XENOTRICHULIDAE Draculiciteria D. tesselata Xenotrichula X. intermedia Total chaetonotids Total species 37

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Archipelago), Ponza (Latium) and Procida (Campania), in Sicily and in Sardinia. It inhabits coarse and shell-rich

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1

0

5

0

3

0

15

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sands and Amphyoxus sediments from the littoral to water depths of over 7 m.

186

F. ELENA, M. G. FAIENZA, S. DE ZIO GRIMALDI, P. TONGIORGI, M. BALSAMO

Mesodasys laticaudatus Remane, 1951 San Domino, station 10, 5 m depth; station 11, 9 m depth.

Mesodasys laticaudatus has been reported in Liguria, Tuscany and the Tuscan Archipelago, Latium and the island of Ponza, Campania, Lucania, Apulia and Sardinia. This species is found in sub-littoral medium to coarse sands with organic detritus, and in organogenic fine sands. Family MACRODASYIDAE Remane, 1926 Genus Macrodasys Remane, 1924

Macrodasys caudatus Remane, 1927 Fig. 2 - Lepidodasys martini: detail of the trunk scales (SEM, X2000)

Family LEPIDODASYIDAE Remane, 1927 Genus Lepidodasys Remane, 1926

Lepidodasys martini Remane, 1926 (Fig. 2) Caprara, station 3, 10 m depth.

The identification of the specimens was certain because of the peculiar herring-bone arrangement of the scales. However, SEM observations showed that the scales actually have only one very thick keel in contrast to Remane's original description (1926). The apparent double keel of scales may be related to misleading optical effects of light microscopy. The species is rare but cosmopolitan and recorded along the coasts of the entire peninsula.

San Domino, station 9, littoral sample, 1 m depth, 2 m depth; station 10, 5 m depth; station 11, 9 m depth.

An adult specimen showed a 85 pm long frontal organ and a caudal organ 114 pm in length and 20 pm in width. Macrodasys caudatus is a cosmopolitan species known from many localities of the peninsular coasts, as well as in the Tuscan Archipelago, Sicily and Sardinia. It inhabits fine to coarse sediments, mostly with organic detritus or even mud, and also Amphyoxus sand and sea-grass beds.

Macrodasys gerlachi Papi, 1957 San Domino, station 9 , 1 m depth.

This is the second finding of the species in Italy. The site was medium sands, while the first recording, in Campania, was in fine sands rich in organic detritus.

Macrodasys thuscus Luporini,

Genus Mesodasys Remane, 1951

Mesodasys adenotubulatus Hummon, Todaro & Tongiorgi, 1993 San Domino, station 10, 5 m depth, 20 m depth.

Mesodasys adenotubulatus has been reported along the Tyrrhenian coasts of Tuscany, Latium, Campania and the island of Ischia, from the Adriatic coast of Marches, and from Sardinia and Sicily. It is commonly found in medium to fine sand.

Magagnini & Tongiorgi, 1973 San Domino, station 8, 12 m depth. Macrodasys thuscus has been reported in Tuscany and Friuli-Venezia Giulia in coarse and very coarse sediments, but never in medium sand. Genus Urodasys Remane, 1926

Urodasys apuliensis n. sp.

Mesodasys ischiensis Hummon,

(Fig. 3)

Todaro & Tongiorgi, 1993 Diagnosis San Domino, station 10, 10 m depth.

The species is known from the Tyrrhenian coast (Latium, Campania and the island of Ischia), the Adriatic coast (Marches) in fine to coarse sand from the littoral to a water depth of 10 m.

Body length 640-670 pm, tail length 1700 urn, head width 52-68 pm, maximum trunk width 77-86 um, pharynx length 268-282 urn; 19-21 lateral adhesive tubes per side (11-13 in the pharyngeal tract, 8 (3+2+3) in the trunk region). Simultaneous hermaphrodite, with the left testis slightly longer than the right. Caudal organ, stylet and frontal organ absent.

MARINE GBASTROTRICHS FROM THE TREMITI ARCHIPELAGO

187

Description The body is 640-670 pm in length; the extremely contractile tail is about 1700 pm long. The head, 52-68 pm in width, has a rounded anterior edge and is not clearly distinct from the trunk. The maximum width of the trunk is 77-86 pm, while the tail is very thin (10 pm, 29 pm at the base). Neither cephalic ciliature nor ventral locomotory ciliature were observed. Cephalic sensory organs were not apparent. At least 22 sensory bristles, 30 pm long, are regularly arranged in a longitudinal row on each side of the body, together with a longitudinal row of numerous, small, rounded glands, 10 x 10 pm. Anterior adhesive tubes were not observed. A row of 11-13 regularly arranged lateral tubes 13-15 pm in length runs along the pharyngeal tract on each side of the body. The first tube is inserted slightly ventrally. There are eight (3+2+3) lateral tubes, 24-27 pm, in the trunk region: three at the anterior edge of each testis, two a slight distance away at the beginning of sperm ducts, and the last three at the posterior end. On each side of the tail, fifty-six caudal tubes, which are shorter than body tubes (6-10 pm), are arranged alternately The mouth is apical and 25 pm in width. The buccal capsule is 26 pm long. The length of the pharynx is 268-282 pm, and the pharynx-body length ratio is 0.4. The pharyngeal pores are sub-terminal (U35). The digestive tract can be divided into a well-developed stomach and a short intestine; the anus is absent. Simultaneous hermaphrodite. Two large testes with bundles of filiform spermatozoa begin just below the pharyngo-intestinal junction, beside the first third of the stomach (U58). The left testis is longer than the right: 93150 pm vs 72-124 pm. Each testis extends into a short sperm duct which turns medially. The presence of a fully-grown oocyte in the trunk region made it impossible to check the confluence of the ducts or the existence of one or two male pores. One specimen shows an evident distal widening of the left sperm duct (seminal vesicle), where a mass of close-packed spermatozoa is visible. Both the caudal organ and the stylet are absent. Two dorso-lateral ovaries lie beside the posterior end of the intestine. Oocytes mature in a posterior-anterior direction, and the fully-grown oocyte (77 x 46 pm) is dorsal and posterior to the testes (from U66 to U78). The frontal organ is absent. Remarks The genus Urodasys includes eleven species, three of which are unnamed. The new species, U. apuliensis, belongs to the group which has neither the caudal organ nor the cuticular stylet: U. elongatus Renaud-Mornant, 1969, U. mirabilis Remane, 1926, U. roscoffensis Kisielewski, 1987 and U. viviparus Wilke, 1954. Urodasys apuliensis is close to the first three species in having both ovaries and testes, with the left testis larger than the right one. On the other hand, it clearly differs from U. viviparus, which is parthenogenetic and viviparous.

Fig. 3 - Urodasys apuliensis n. sp., dorsal view.

Urodasys mirabilis differs from U. apuliensis n. sp. because it has eight lateral tubes gathered along the pharyngeal tract and ten others along the trunk. U. roscoffensis shows seven lateral and two-four dorso-lateral tubes along the pharyngeal tract, and a smaller number (five) along the trunk. Urodasys elongatus is notably smaller in size (only 250-350 pm in body length), and shows two clusters of four anterior tubes each which are absent in the other species. Moreover, it has four lateral and six ventral-lateral tubes along the pharyngeal tract of each side of the body. A possible evolution of the genus and the systemic position of Urodasys apuliensis are outlined in the final discussion. Distribution Type locality: Tremiti Archipelago (Foggia, Apulia), island of San Domino, Grotta delle Viole, 9 m depth. Other locality: Monopoli (Bari, Apulia) 'Grotta di Cala Corvino', 10 m depth, Polignano, Cala Paura, 5 m depth. Derivatio nominis From 'Apulia', the Latin name of the Italian region in which the type locality of the species is situated.

188

F. ELENA, M. G. FAIENZA, S. DE ZIO GRIMALDI, P. TONGIORGI, M. BALSAMO

XJrodasys bucinastylis n. sp.

The body is 375-456 pm and the extremely contractile tail about 1500 pm long. The head has a rounded anterior edge, is not clearly distinct from the trunk and is 47-50 pm wide. The maximum width of the trunk is 7585 pm (Figs 4, 5). The cephalic ciliature consists of a row of about ten cilia per side. These are 19-21 pm in length and run parallel to the cluster of anterior tubes. Cephalic sensory organs (piston pits) were not observed. There are 29-30 sensory bristles (20 pm) regularly arranged in a longitudinal row on each side, as well as 19-22 oval

epidermal glands (12.5 x 7 pm), again regularly arranged, along each side of the body. The ventral body surface is covered anteriorly up to U52 by a continuous ciliary field and posteriorly by two longitudinal, parallel ciliary bands. A cluster of three-four anterior adhesive tubes (9.7 pm) is located on each ventral side of the head (Fig. 6). On each side of the body, there is a longitudinal row of twenty-one-twenty-three 12.5 pm long adhesive tubes. Only the first tube is lateral (U9). A longitudinal row of sixteen-seventeen ventral-lateral tubes runs along each side of the body. The first five-seven are regularly spaced along the pharyngeal region, one is located just posteriorly to the pharyngo-intestinal junction, five-six are arranged along the trunk region, and the last three, slightly separated from the others, are at the level of the stylet from U88 to U94. A row of six dorso-lateral tubes per side (10 pm long) is composed of three tubes on the posterior pharyngeal tract from U27 to U40, one between the 9th and 10th ventral-lateral tubes (U52), and two just anterior to the last ventral-lateral tubes from U85 to U88. Forty-two-forty-five short tubes (8.3 pm) are inserted alternately on each side of the tail. The mouth is 20 pm wide and apical. The pharynx is 165-207 pm long and shows sub-terminal pores at U38.

Fig. 4 - Urodasys bucinastylis n. sp., dorsal view.

Fig. 5 - Urodasys bucinastylis n. sp., habitus of an adult specimen (Nomarski optics, x45O)

(Figs 4-7) Diagnosis Body length 375-456 pm; tail length 1500 pm, head width 47-50 pm, maximum trunk width 75-85 pm, pharynx length 165-207 pm, a cluster of 3-4 anterior, ventral adhesive tubes per side, one lateral cephalic tube, 16-17 ventral-lateral tubes per side (5-7 along the pharyngeal tract and 8-9 on the trunk), 6 dorso-lateral tubes (3 on the pharyngeal region, 3 on the trunk). Testes absent; caudal organ with a rolled up, complex cuticular stylet shaped like a French horn. Two dorso-lateral ovaries; frontal organ absent.

Description

189

MARINE GBASTROTRICHS FROM THE TREMITI ARCHIPELAGO

50 .Mm

Fig. 6 - Urodasys bucinastylis n. sp., ventral side of the head.

The pharynx-body length ratio is 0.4. The digestive tract includes a swollen anterior stomach and a short, blind intestine. The specimens observed did not show testes. The caudal organ 40-45 pm long and folded, as is typical for the Urodasys genus, and lies just posteriorly to the ovaries. Its anterior part is glandular, while the posterior is muscular and contains a complex cuticular stylet rolled up in one and half turns (Figs 7A, B). When rolled up the stylet measures 20 x 29 pm in diameter, while when it is unrolled the total length reaches 81-82 pm. Its basal part is funnel-shaped, while the distal part is tapered with the point directed laterally. The distal end of the stylet is enveloped in a funnel-shaped muff which looks like those in Urodasys acanthostylis and U. uncinostylis (Fregni et al, 1998). We propose to name this structure 'conductor1, since it probably allows the correct gliding of the stylet. The external pore of the caudal organ was not observed. Two ovaries lie dorso-laterally to the caudal organ (U89). The oocytes mature in an anterior direction. Two full-grown oocytes (51.5 pm) were observed in all the Fig. 7 - Urodasys bucinastylis n. sp. A, schematic drawing of the specimens studied, one on each body side from U63 to cuticular stylet; B, the cuticular stylet into the caudal organ (Nomarski optics, xl600) U79. The frontal organ is absent. Remarks Due to the peculiar shape of the stylet and the body size, the specimens can be assigned with certainty to Urodasys sp. 2, the species found by Schoepfer-Sterrer at Banyuls-sur-Mer in France (1974). All the individuals collected showed two mature oocytes rather than one, and the caudal organ equipped with the cuticular stylet, but did not have testes. This might suggest that Urodasys bucinastylis reproduces by parthenogenesis, maintaining both the caudal organ and the stylet as vestigial elements. An alternative hypothesis is that the individuals studied were in the first, female phase of a proteroginic reproductive cycle. However, a proteroginy has never been reported for the Urodasys genus, nor for any other macrodasyid. The phylogenetic relationships of the species in the Urodasys genus and the systemic position of Urodasys bucinastylis are considered in the final discussion.

Distribution Type locality: Tremiti Archipelago (Foggia, Apulia), island of San Domino, Grotta delle Viole, 9 m depth. Other localities: Tremiti Archipelago (Foggia, Apulia), island of San Domino, Grotta del Sale, 9 m depth; Monopoli (Bari, Apulia), Grotta di Cala Corvino, 10 m depth; Polignano, Cala Paura, 5 m depth. Derivatio nominis From the Latin 'bucina', a spiral-shaped musical instrument like a horn referring to the shape of the cuticular stylet.

Urodasys viviparus Wilke, 1959 San Domino, station 8, 12 m depth; station 10, 10 m depth; station 11, 9 m depth.

F. ELENA, M. G. FAIENZA, S. DE ZIO GRIMALDI, P. TONGIORGI, M. BALSAMO

190

Urodasys viviparus is widespread along the Tyrrhenian coasts (Tuscany, the Tuscan Archipelago, Campania), the Adriatic coasts (Apulia, Friuli-Venezia Giulia) and in Sardinia in fine to coarse sand of the sub-littoral. Family PLANODASYIDAE Rao & Clausen, 1970 Genus Crasiella Clausen, 1968

Crasiella sp.

erotubulatum inhabits fine to coarse sands of the littoral and sub-littoral.

Tetranchyroderma hypopsilancrum Hummon, Todaro & Tongiorgi, 1993 San Domino, station 9, 1 m depth.

Tetranchyroderma hypopsilancrum has been reported along the Tyrrhenian coasts of Tuscany and Campania, the Ionian and Adriatic coasts of Apulia, in Veneto and in Sicily. It is usually found in littoral and sub-littoral sediments of fine to medium sand.

Caprara, station 1, 12 m depth

The only specimen collected was a sub-adult, so its assignation to this genus was certain, but specific identification was not possible. This is the first recording of the genus as well as of the family in Italy and in the Mediterranean. Of the four known species of Crasiella, only C. diplura has been reported in Europe, in a Norwegian fjord, in coarse shell gravel. Family THAUMASTODERMATIDAE Remane, 1926

Tetranchyroderma polypodium Luporini, Magagnini & Tongiorgi, 1973 San Domino, station 8, 12 m depth.

The caudal feet of the specimens studied were composed of only two rather than three tubes. Tetranchyroderma polypodium is a rare species, reported in Italy only in Tuscany and Sardinia in medium to very coarse sand.

Tetranchyroderma sardum Todaro, Balsamo & Tongiorgi, 1988

Genus Acanthodasys Remane, 1927

Acanthodasys aculeatus Remane, 1927 Caprara, station 1, 12 m depth.

All the specimens collected were longer in body size than reported in the literature: 988 pm vs 800 um. This is a common species known along the entire Italian coastline, in Sicily and in Sardinia. The species seems to prefer fine sand rich in organic detritus, even it is also found in fine to coarse and Amphyoxus sand. Genus Platydasys Remane, 1927

Platydasys sp. San Domino, station 7, 10 m depth

The only specimen found was a hermaphrodite adult, but it was too damaged to be identified with certainty. Genus Tetranchyroderma Remane, 1926

Tetranchyroderma heterotubulatum Hummon, Todaro & Tongiorgi, 1993 San Nicola, station 6, 9 m depth; San Domino, station 11, 9 m depth.

The Italian distribution of the species is widespread: it has been found in Tuscany and the Tuscan Archipelago, Latium and the island of Ponza, Campania and the island of Ischia, along the Ionian coasts of Lucania, in Apulia and Friuli, and in Sicily. Tetranchyroderma het-

San Domino, station 9, littoral sample, 1 m depth.

The first finding in Sardinia has been followed by recordings of the species on the island of Ischia and along the coasts of Campania (Hummon & Todaro, unpublished data), as well as in Sardinia and Sicily in medium to coarse sand of the sub-littoral.

Tetranchyroderma thysanogaster Boaden, 1965 San Nicola, station 6, 9 m depth; San Domino, station 9, 1 m depth; station 11,9m depth.

Tetranchyroderma thysanogaster has a preference for fine and medium sands. It is known in the Tuscan Archipelago, along the coasts of Campania and in Sardinia. Tetranchyroderma thysanophorum Hummon, Todaro & Tongiorgi, 1993 San Nicola, station 4, 18 m depth; San Domino, station 11, 9 m depth.

The morphology and dimensions of the two specimens found agree with the data in the literature, with the exception of the presence of eight intrafurcal tubes rather than six. The habitat of this species is medium and fine sands of the sub-littoral. In Italy, it has been found along the coasts of Liguria and Tuscany, in the Tuscan Archipelago, in Latium, on the islands of Ponza and Ischia, in Campania, Sardinia and Sicily. Genus Thaumastoderma, 1927 Thaumastoderma heideri Remane, 1926 San Nicola, station 4, 18 m depth; San Domino, station 7, 10 m depth; station 8, 12 m depth; station 9 , 1 m depth; station 11, 9 m depth.

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MARINE GBASTROTRICHS FROM TOE TREMITC ARCHIPELAGO

This is the first recording of Thaumastoderma heideri in Italy and the Mediterranean Sea. The species is rare, and is known in the Atlantic and along the northern coasts of Europe in fine to coarse sands. Family TURBANELLIDAE Remane, 1925 Genus Paraturbanella Remane, 1927

Paraturbanella dohrni Remane, 1927 San Domino, station 9 , 1 m depth; station 10, 10 m depth.

The only specimen studied was larger than reports for this species, although the number of tubes on the body and tail was consistent with the original description. Paraturbanella dohrni is a common species mostly in fine sandy sediments. In Italy, it is widespread along the Ligurian and Tyrrhenian coasts (Tuscany, the Tuscan Archipelago, Campania, Calabria), the Ionian coast (Lucania and Apulia and the Adriatic littoral (Apulia, Molise, Abruzzi, Marches, Veneto, Friuli), and in Sardinia and Sicily.

Paraturbanella pallida Luporini, Magagnini & Tongiorgi, 1973

Aspidiophorus mediterraneus is cosmopolite and colonises substrates of different grain size. Its distribution in Italy is widespread, extending from Liguria to the Tyrrhenian coasts (Tuscany and the Tuscan Archipelago, Latium, Campania and the island of Ischia), the Ionian (Apulia) and Adriatic coasts (Veneto, Friuli), Sardinia and Sicily. Aspidiophorus paramediterraneus Hummon, 1974 Caprara, station 1, 34 m depth; San Nicola, station 5, 20 m depth; San Domino, station 9, 1 m depth; station 10, 5 m depth, 10 m depth, 20 m depth; station 11,9 m depth.

The species is known in Liguria, Tuscany and the Tuscan Archipelago, Latium, the island of Ischia (Campania), Apulia, Abruzzi, Marches, Veneto, Friuli, Sardinia and Sicily. It inhabits fine to coarse sediments of the sub-littoral. Genus Chaetonotus Ehrenberg, 1830 Subgenus Euchaetonotus Schwank, 1990

Chaetonotus (E.) aegilonensis Balsamo, Todaro & Tongiorgi, 1992

San Nicola, station 6 , 9 m depth; San Domino, station 9, 2 m depth.

Caprara, station 3, 11 m depth.

The individuals collected were smaller than the original description (the length of body was 450-537 pm vs 600-650 um, the length of pharynx was 135-178 pm vs 190-200 pm) The first report of Paraturbanella pallida was along the medium sub-littoral zone of the Tuscan coast (Leghorn) in sand rich in organic matter at 3-4 m depth. Subsequently, the species was found along the coasts of Liguria, in the Tuscan Archipelago, in Campania, on the island of Ischia, in Apulia, Marches, Veneto, Friuli, Sardinia and Sicily.

Metric parameters of the specimens were slightly smaller than those reported in the literature (the length of body was 150-175 pm vs 200 pm, the length of pharynx was 32.5-38.5 pm vs 41.0 pm and the length of the furca was 32.5 pm vs 36.0 pm). Chaetonotus aegilonensis has so far been recorded along the coasts of Tuscany, in the Tuscan Archipelago and in Sardinia in medium sand rich in detritus.

Genus Turbanella Schiiltze, 1853

Turbanella subterranea Remane, 1934 San Domino, station 11, 9 m depth.

The only specimen found was damaged, meaning that the main morphometric measurements could not be recorded. Nevertheless, some morphological features, in particular the number of anterior and caudal tubes and the presence of very short, lateral tubes always joined to a sensory bristle, enabled specific identification. Turbanella subterranea is reported in Italy for the first time. Order Chaetonotida Rao & Clausen, 1970 Family CHAETONOTIDAE Zelinka, 1889

Chaetonotus (E.) apechochaetus Hummon, Balsamo & Todaro, 1992 Caprara, station 3, 10 m depth; San Nicola, station 4, 18 m depth.

The species has been collected in Liguria, Tuscany, the Tuscan Archipelago, Campania and the Campanian Archipelago, along the Ionian coast of Apulia, in Sardinia and Sicily.

Chaetonotus (E.) siciliensis Hummon, Balsamo & Todaro, 1992 San Domino, station 9 , 1 m depth; station 10, 5 m depth.

Chaetonotus siciliensis is known from the coasts of Tuscany and Tuscan archipelago, the island of Ponza, Molise, Apulia, Sardinia and Sicily. It inhabits sediments of various grain size.

Genus Aspidiophorus Voigt, 1904

Subgenus Schizochaetonotus Schwank, 1990

Aspidiophorus mediterraneus Remane, 1927

Chaetonotus (S.) atrox Wilke, 1954

San Domino, station 10, 5 m depth.

Caprara, station 3, 10 m depth; San Domino, station 11, 9 m depth.

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192

The specimen from the island of Giglio was slightly smaller in body length compared to reports in the literature, 136 um vs 150 um. Chaetonotus atrox is quite common and widespread in Italy, having been collected in Liguria, Tuscany and the Tuscan Archipelago, Campania and the Campanian Archipelago, along the Ionian coasts of Calabria, and in Apulia, Molise, Marches, Friuli and Sardinia. The species is found both in littoral and sub-littoral zones in sediments of various grain size. Chaetonotus

(S.) dispar Wilke, 1954

The specimens collected were slightly larger than reported in the literature (body length was 107-120 pm vs 105-110 pm, pharynx length was 33.5 pm vs 31.0 pm and the furca length of was 16-19 pm vs 14 pm). Heterolepidoderma loricatum is a widespread species in Italy, where it is known in Liguria, Tuscany, the Tuscan Archipelago, Latium, the island of Ponza, Campania, the island of Ischia, Apulia, Abruzzi, Marches, Veneto, Friuli, Sardinia and Sicily. Generally found in fine sand, the species has also been collected in very coarse littoral sediments.

Caprara, station 3, 7 m depth; San Domino, station 8, 12 m depth; station 11, 9 m depth.

Famiglia XENOTRICHULIDAE Remane, 1926

The morphometric parameters of the specimens matched the data in the literature with the exception of the furca length, which was slightly shorter, 25 um vs 35 pm. Chaetonotus dispar is a common species both in littoral and sub-littoral sand of various grain size. In Italy, it has been reported in Tuscany and the Tuscan Archipelago, Latium, Campania, on the island of Ischia, along the Tyrrhenian coast of Calabria, and in Apulia, Friuli, Sardinia and Sicily.

Genus Draculidteria Hummon, 1974

Chaetonotus (S.) hilarus Schrom, 1972 San Domino, station 9, littoral sample.

This rare species is only known along the Adriatic coast of Emilia-Romagna and Veneto in fine sands even rich in detritus.

Chaetonotus (S.) luporinii Balsamo, Fregni & Tongiorgi, 1996 Caprara, station 3, 10 m depth; San Nicola, station 4, 18 m depth; station 5, 20 m depth; San Domino, station 9, 1 m depth; station 11, 9 m depth.

Draculiciteria tesselata Renaud-Momant, 1968 San Domino, station 9 , 1 m depth.

The specimens from the Tremiti islands were notably larger than those described in the literature (body length was 295-302 pm vs 165 pm). The species is known along the coasts of Tuscany, in the Tuscan Archipelago, Latium, on the island of Ponza, in Campania, on the island of Ischia, in Apulia, Marches, Veneto, Friuli and Sardinia. It is mainly found in fine, littoral sediments. Genus Xenotrichula Remane, 1927 Xenotrichula intermedia Remane, 1927 San Domino, station 11, 9 m depth. A cosmopolitan species widely present in Italy along both the western (Liguria, Tuscany and the Tuscan Archipelago, Latium, Campania and Calabria) and the eastern coasts (Apulia, Abruzzi, Marches, Emilia-Romagna, Veneto and Friuli), in Sardinia and Sicily. It is usually present in fine sands, even with detritus.

The specimens were generally larger than those reported in the literature (body length was 250-342 pm vs 100-236 pm, and body width was 43.6-58.0 pm vs 30-40 pm; furca length 40.0-47.5 pm vs 14-34 pm). Chaetonotus luporinii was previously found only along the coasts of Tuscany and Sicily (Taormina) in littoral sediments DISCUSSION with medium grain size at up to 2-3 m depth. The large number of species (37) found in the Tremiti Archipelago is evidence of the greater faunistic richness Chaetonotus (S.) neptuni Wilke, 1954 of these islands compared to the small Tyrrhenian islands where altogether 54 species were recorded on ElSan Domino, station 8, 12 m depth. ba, Giglio and Capraia (Todaro et al, 1992), 20 species In Italy, the species has been recorded in Tuscany, on Ponza (Todaro, 1992) and 19 species on Montecristo the Tuscan Archipelago, Campania, on the island of Is(Balsamo et al, 1994). A similar number of species has chia, in Apulia and Sardinia. It is mainly found in fine been recorded for the two major islands: 55 species on and medium sand, but also in Amphyoxus sand. Sardinia (Balsamo et al., 1995) and 41 species on Sicily (Balsamo et al, 1996). Genus Heterolepidoderma Remane, 1926 The number of species per site is low, from 1 to 6, except for sites 9 (1 m depth) and 10 (9 m depth) on Heterolepidoderma loricatum Schrom, 1972 the Island of San Domino, at which 12 and 15 species, respectively, were recorded, numbers which appear San Nicola, station 4, 18 m depth; San Domino, station 9, 1 m depth. high for sites sampled once.

MARINE GBASTROTRICHS FROM THE TREMITI ARCHIPELAGO

193

Most samples were taken between 10 m and 54 m depth, which distinguishes this research from previous studies concerning the littoral and shallow sub-littoral zone from 3-5 m down to 8-10 m depth (island of Montecristo). The transparency of the waters of the Tremiti Archipelago is such that the coralligenous biocoenosis flourishes as deep as 35 m, whereas the turbid sea along the Apulian coast limits the presence of the biocoenosis to a depth of 10-15 m (Marano et al, 1992). However, almost all species found at greater depth are also present in shallower water, as well as in the littoral. Unlike other factors such as salinity, the hydrodynamic characteristics of the sediment and its silt and organic matter content, depth does not seem to limit the spatial distribution of gastrotrichs. There are references in the literature pointing out that gastrotrichs are able to colonise deep sediments (Swedmark, 1956; d'Hondt, 1971): significant in this respect is the recording in 1974 of Chordodasys antennatum at a depth of 97 m along the Atlantic coast of USA (Rieger et al., 1974) and of Muselliferprofundus in maddy sediment at 370 m depth in the Mediterranean Sea off Marseille (Vivier, 1974). The data show a slight decrease in species number as the depth of the sampling site increases. That is in contrast with the results of a recent study showing that the average number of the species found at depths ranging from 1 to 47 m is reasonably uniform, with just a slight increase between 1 and 6 m (Fregni & Tongiorgi, unpublished data).

%

U. acanthostyts U. calicostylis U. comusfyf/s

U. nodostylis U nmostytls . U. spirostylis U. unctnostyils U. sp.1 Sctixp.Ster U. sp.2 Valb. I Lup. U.budnastylisnsp.

U. vMparus

Possible evolution of the reproductive system in the genus Urodasys

Fig. 8 - The two hyphotetic evolutionary lines of the reproductive system in the genus Urodasys.

The different morphology of the reproductive system of the new species U. apuliensis and U. bucinastylis allows to the evolutionary picture of the genus Urodasys outlined some years ago by Schoepfer-Sterrer (1974) to be revised. Four morphological situations are evident, reflected in as many groups of the Urodasys species. 1 - simultaneous hermaphrodite species with two identical or slightly different testes (U- elongatus, U. roscoffensis), or even quite different testes (£/. mirabilis), but without a caudal organ, stylet or frontal organ. The latter is recognisable in a vestigial form only in U. mirabilis. Urodasys apuliensis n. sp. belongs to this group; 2 - simultaneous hermaphrodite species with only one testis, the left, and with both a caudal organ equipped with a complex stylet and a frontal organ (U- acanthostylis, U. calicostylis, U. cornustylis, U. nodostylis, U. remostylis, U. spirostylis, U. uncinostylis and U. sp.l Schoepfer-Sterrer, 1974). If Valbonesi and Luporini (1984) are right in seeing only one testis in Urodasys sp. 1, even this species belongs to this group although it lacks a frontal organ. Otherwise it would be a member of the following group; 3 - obligate parthenogenetic species which have lost both testes but still maintain the stylet, e.g. U. bucinastylis n. sp. The very similar morphology of the stylet

in this species and that in the species in group 2 should be stressed; 4 - obligate parthenogenetic species which have lost the testes as well as the caudal organ with stylet and have become viviparous (£/. viviparus). From this overview, two evolutionary lines of the reproductive system in the genus Urodasys may be hypothesised, both perhaps arising from a primitive plan composed of two testes, two ovaries, a frontal organ and a caudal organ with stylet (Fig. 8). The first line maintains two testes, even if the right one tends to decrease in size through lack of development or early loss, a caudal organ with stylet, and a frontal organ which regresses considerably up to complete disappearance. The second line shows an early, complete regression of the right testis, followed by that of the left one, and disappearance of the frontal organ, but maintains the caudal organ with stylet, which may be considered a vestigial feature. The obligate parthenogenetic forms, which lack testes, frontal organ and even a caudal organ with stylet, may have evolved from either of the two evolutionary lines: by progressive regression of the testes in the first case, or by disappearance of the caudal organ and stylet in the second.

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REFERENCES Balsamo M., Todaro M. A., Tongiorgi P., 1992 - Marine gastrotrichs from Tuscan Archipelago (Tyrrhenian Sea). II. Chaetonotida, with description of three new species. Boll. Zool., 59: 487-498. Balsamo M., Fregni E., Tongiorgi P., 1994 - Marine and freshwater Gastrotricha from the Island of Montecristo (Tuscan Archipelago, Italy), with the description of new species. Boll. Zool., 61: 217-227 Balsamo M., Fregni E., Tongiorgi P., 1995 - Marine Gastrotricha from the coasts of Sardinia (Italy). Boll. Zool., 62: 273- 286. Balsamo M., Fregni E., Tongiorgi P. 1996 - Marine Gastrotricha from Sicily with the descriptions of a new species of Chaetonotus. Ital. J. Zool., 63: 173 - 183. Clausen C., 1968 - Crasiella diplura gen. et sp. n. (Gastrotricha, Macrodasyoidea). Sarsia, 33: 59-64. Fregni E., 1995 - Gastrotrichi interstiziali marini e dulciacquicoli: indagini faunistiche, sistematiche e filogenetiche. PhD Thesis, Università di Modena (Italy). Fregni E., Tongiorgi P., Faienza M. G., 1998 - Two new species of Urodasys (Gastrotricha, Macrodasyidae) with cuticular stylet. Ital. J. Zool., 65: 377-380. Higgins R. P., 1983 - The Atlantic Barrier Reef. Ecosystem at Carrie Bow Cay, Belize. II: Kinorhyncha. Smithson. Contrib. mar. Sci., 18: 1-131. Higgins R. P., Thiels H., 1993 - Introduction to the study of meiofauna. Smithsonian Institution Press, Washington, 488 pp. d'Hondt J., 1971 - Gastrotricha. Oceanogr. mar. Biol. Annu. Rev., 9: 141-192. Hummon W. D., Balsamo M., Todaro M. A. 1992 - Italian marine Gastrotricha: I. Six new and one redescribed species of Chaetonotida. Boll. Zool., 59: 499-516. Hummon W. D., Todaro M. A., Tongiorgi P., 1993 - Italian marine

Gastrotricha: II. One new genus and ten new species of Macrodasyda. Boll. Zool., 60: 109-127. Hummon W. D., Todaro M. A., Balsamo M., Tongiorgi P., 1996 Italian marine Gastrotricha: III. Four new pentancrous species of the genus Tetranchyroderma (Macrodasyida, Thaumastodermatidae). Ital. J. Zool., 63: 73-79. Hummon W. D., Todaro M. A., Tongiorgi P., Balsamo M., 1998 Italian marine Gastrotricha: V. Four new and one redescribed species of Macrodasyida in the Dactylopolidae and Thaumastodermatidae. Boll. Zool., 65: 109-119. Marano G., Vaccarella R., Amato E., De Zio V., Rositani L., Pastorelli A. M., 1992 - Indagini preliminari sul Parco marino delle Isole Tremiti - Preliminary investigation about Tremiti marine Reserve. Oebalia (1992) suppl. XVII: 509-515. Rieger R. M., Ruppert E., Rieger G. E., Schoepfer-Sterrer C., 1974 On the fine structure of Gastrotrichs with description of Chordodasys antennatum sp. n. Zool. Scripta, 3: 219-237. Schoepfer-Sterrer C., 1974 - Five new species of Urodasys and remarks on the terminology of the genital organs in Macrodasyidae (Gastrotricha). Cah. Biol. mar., 15: 229-254. Swedmark B., 1956 - Étude de la microfaune des sables marins de la region de Marseille. Archs. Zool. exp. gén., 93: 70-95. Todaro M. A., 1992 - Contribution to the study of the Mediterranean meiofauna: Gastrotricha from the Island of Ponza, Italy. Boll. Zool., 59: 321-333. Todaro M. A., Balsamo M., Tongiorgi P., 1992 - Marine gastrotrichs from the Tuscan Archipelago (Tyrrhenian Sea): I. Macrodasyida, with description of three new species. Boll. Zool., 59: 471 485. Valbonesi A., Luporini P., 1984 - Researches on the coasts of Somalia. Gastrotricha Macrodasyoidea. Monit., zool. ital., 19: 1-34. Vivier M. M., 1974 - Musellifer profundus n.sp., Gastrotricha (Chaetonotidae) des vases profondes de Mediterranee. Bull. Soc. zool. France, 99: 183-186.