189Porifera research: Biodiversity, innovation and sustainaBility - 2007

Introduction

The existence of submarine canyons on the continental shelf of Argentina was known (Parker et al. 1997), but their exact location, number, edaphic and biotic conditions remain unstudied. During a research to assess the distribution and abundance of the Patagonian scallop Zygochlamys patagonica (King and Broderip, 1832), a submarine canyon was discovered.

The Patagonian scallop is distributed in the Magellanic Biogeographical Province and its exploitation results in the destruction of associated species. Porifera are particularly affected (Schejter et al. 2006). The Argentinian sponge fauna is relatively well known; with the earliest studies commencing in the 19th century (Ridley and Dendy 1886, 1887, Sollas 1886, 1888, Schulze 1887). More recent contributions include Boury-Esnault (1973), Sarà (1978), Mothes de Moraes and Pauls (1979), and particularly Cuartas (1986, 1991, 1992a, 1992b, 1992c, 1995). Despite our knowledge of the Argentinian sponge fauna, a recent paper on the Porifera associated with commercial Patagonian scallop beds reported four new records for the area (Schejter et al. 2006).

Here we describe 9 species of demosponges recorded in a canyon close to scallop beds. In particular Pseudosuberites cf. antarcticus Carter, 1876 and Guitarra dendyi (Kirkpatrick, 1907) were previously known only for the Antarctic area, representing new records for the Argentine Sea, while two (Stelodoryx argentinae sp. nov. and Tedania (Tedaniopsis) sarai sp. nov.) are new to science.

Materials and methods

The canyon was discovered using a multibeam SIMRAD EM1002 sonar, during a research cruise (R/V “Oca Balda”, INIDEP, April 2005) for assessment of the Patagonian scallop (Zygochlamys patagonica). The canyon is positioned at 43º35’S and 59º33’W, close to the southern commercial scallop beds, in the Argentine Sea (Fig. 1). Sampling was carried out on board the R/V “Oca Balda” (INIDEP, National Fisheries Research and Development Institute) during April 2005, at 360 m depth. The samples were labelled OB-4-05 with the indication of the ship (“Oca Balda”) and the date of collection, and with progressive numbers (e.g. OB-4-05 cañon 14).

Specimens were frozen upon collection and fixed in 5% formaldehyde in sea water and then preserved in alcohol 70%, or dried, in the laboratory.

For the study of spicules, small fragments of sponge tissue were heat-dissolved in nitric acid, rinsed in water, and dehydrated in ethanol; then spicules were mounted on microscope slides. Spicule dimensions are given as range of lengths and of widths and as average (in brackets); they were obtained measuring 20 to 30 spicules per category. Sections were cut by hand, perpendicularly and tangentially to the sponge surface, using a razor blade. For SEM analyses spicule dissociations were transferred onto stubs and sputter-coated with gold. SEM studies were carried out on a Philips XL 20 scanning electron microscope. Photographs of the specimens were taken using a Nikon Coolpix 4500.

Sponges from a submarine canyon of the Argentine SeaMarco Bertolino(1), Laura Schejter(2), Barbara Calcinai(3*), Carlo Cerrano(1), Claudia Bremec(2)

(1) Dipartimento per lo studio del Territorio e delle sue Risorse, C.so Europa, 26, 16132, Genova, Italy. marco.bertolino75@libero.it, cerrano@dipteris.unige.it

(2) Laboratorio de Bentos, Instituto Nacional de Investigación y Desarrollo Pesquero, Paseo Victoria Ocampo 1, (B7602HSA) Mar del Plata, Argentina schejter@inidep.edu.ar, cbremec@inidep.edu.ar

(3) Dipartimento di Scienze del Mare, Via Brecce Bianche, 60131, Ancona, Italy. b.calcinai@univpm.it

Abstract: During a research cruise to assess the abundance and distribution of Patagonian scallop Zygochlamys patagonica (King and Broderip, 1832), a submarine canyon was discovered using a multibeam SIMRAD EM1002 sonar. The canyon is positioned at 43º35’S and 59º33’W, close to the southern commercial scallop beds in the Argentine Sea. The existence of submarine canyons on the continental shelf of Argentina was already known, but their edaphic and biotic conditions remain unstudied. A sample of the benthic community was collected at the “head” of the canyon at 360 m depth. In total nine species of demosponges were identified; two of them represent new records for the Argentine Sea and two are new to science.

Keywords: Argentina, new records, new species, Porifera, submarine canyon

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The present collection is preserved at the Laboratorio de Bentos, Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP). The type materials of the new species here described are deposited at the Museo Civico di Storia Naturale G. Doria of Genoa (MSNG).

Results

In total nine species were identified. Craniella leptoderma (Sollas, 1886), Myxilla (Myxilla) mollis Ridley and Dendy, 1886, Tedania (Tedaniopsis) charcoti Topsent, 1907, Tedania (Tedaniopsis) massa Ridley and Dendy, 1886 and Tedania (Trachytedania) mucosa Thiele, 1905 are already known for the area. Pseudosuberites cf. antarcticus Carter, 1876 and Guitarra dendyi (Kirkpatrick, 1907) were previously known only for the Antarctic area and so they represent new records for the Argentine Sea. Stelodoryx argentinae sp. nov. and Tedania (Tedaniopsis) sarai sp. nov. are new for science. All species dealt with are described below.

Fig. 1: Location of the canyon and of the sampling station in the Atlantic Ocean, Argentine Sea, Argentina.

Class Demospongiae Sollas, 1885Order Spirophorida Bergquist and Hogg, 1969

Family Tetillidae Sollas, 1886Genus Craniella Schmidt, 1870

Craniella leptoderma (Sollas, 1886)

Examined material: OB-4-05: cañon 14, cañon 15Sponge round or elongate, egg-shaped (Fig. 2A, B).

Surface hispid, conulose. Several small oscules are located on the tip of the sponge conules (Fig. 2A). In cañon 15 the surface is more regular (without conules) and more hispid (Fig. 2B). The consistency is hard. The colour is dirty white, or brown-pinkish in alcohol. Skeleton: Spicule tracts radiate from the centre of the sponge towards the surface (Fig. 2C).Spicules: Megascleres are large oxeas, fusiform; they are frequently broken. Small oxeas (Fig. 2D), straight or slightly curved, frequently centrotylote. They measure 540 (913.6) 1500 x 5 (25) 30 µm. Anatriaenes 1, with thin clads (Fig. 2E). The rhabdomes are frequently broken; the clads measure 100 (150) 200 x 15 (18) 20 µm. Anatriaenes 2, with thick and short clads 70 (105) 120 x 20 (32.5) 40 µm (Fig. 2F). Rhabdomes are frequently broken. Protriaenes 1, with rhabdomes that reach more than 8 cm in length, while the clads are 40 (140.5) 200 µm long (Fig. 2G). Protriaenes 2 are filiform, up to 1 cm long (Fig. 2H) and with a clad longer than the others; the long clads are 26 (32.5) 44 µm long and the short ones 10 µm long. Microscleres are spinispires (Fig. 2I); they measure 5 (7.8) 10 µm.Distribution: Antarctic shores, South Georgia, Straits of Magellan, Malvinas, Kerguelen and Heard Islands (Sarà et al. 1992), South Shetland Islands (Ríos et al. 2004), Chile, Atlantic coast of South America (mouth of the Rio de la Plata) (Desqueyroux-Faúndez 1989).Remarks: This species has a highly variable habitus; the body is round, elongate egg-shaped (Koltun 1964) or massive, spherical (Desqueyroux-Faúndez 1989); the surface varies from even and smooth, to more or less bristly (Koltun 1964), to strongly hispid (Desqueyroux-Faúndez 1989).

Order Hadromerida Topsent, 1894Family Suberitidae Schmidt, 1870

Genus Pseudosuberites Topsent, 1896

Pseudosuberites cf. antarcticus Carter, 1876

Examined material: OB-4-05: cañon 6, cañon 10Massive sponge (Fig. 3A) with a cavernous structure

covered by remains of a thin membrane easily detachable from the sponge body. The consistency is soft. The colour is beige-grey in alcohol. The sample cañon 6 hosted numerous samples of the bivalve Hiatella solida (Sowerby, 1834).Skeleton: The ectosomal skeleton is made of tylostyles tangentially arranged (Fig. 3B); the choanosomal skeleton is made of well defined spicule tracts running towards the surface (Fig. 3C).Spicules: Tylostyles and subtylostyles (Fig. 3D-H), often slightly curved. They have well formed heads (Fig. 3H),

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Fig. 2: A, B. Specimens of Craniella leptoderma (Sollas, 1886); C. Radial skeleton; D. Small oxeas; the arrow points the central tyle; E. Anatriaene 1; F. Anatriaene 2; G. Protriaene 1; H. Protriaene 2; I. Spinispires.

sometimes sub-terminal (Fig. 3G) and acerate tips (Fig. 3E). They measure 350 (1063.6) 1350 x 5 (15.6) 25 µm.Distribution: Antarctic shores, Heard and Kerguelen Islands (Koltun 1964).Remarks: This specimen is easily recognisable as Pseudosuberites antarcticus Carter, 1876 in spicule characteristics (comparable size and shape), but it differs from the holotype as well as from other records of the species, in the habitus. Pseudosuberites antarcticus was previously reported as erect and ramified (Ridley and Dendy 1887, Topsent 1902). This represents a new record for the Argentine Sea that enlarges the known distribution of this species northwards.

Order Poecilosclerida Topsent, 1894Suborder Myxillina Hajdu, van Soest and Hooper, 1994

Family Myxillidae Dendy, 1922Genus Myxilla Schmidt, 1862

Myxilla (Myxilla) mollis Ridley and Dendy, 1886

Examined material: OB-4-05: cañon 3Massive sponge with an irregular surface and an irregular

system of cavities (Fig. 4A). No dermal membrane was present. The sponge is compressible and elastic. The colour is beige in alcohol.Skeleton: The ectosomal skeleton is absent. The choanosome is a loose reticulation of smooth styles and anisotylotes (Fig.

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isochelas 2 of similar shape (Fig. 4F). They measure about 20 µm. Sigmas 1 are C- or S- shaped (Fig. 4G, H). They measure 40 (51) 60 µm. Sigmas 2 are C- shaped (Fig. 4F). They measure 15 (25) 30 µm.

Distribution: West and East coast of South America; Malvinas Islands (Desqueyroux-Faúndez and van Soest 1996); Antarctic shores; Strait of Magellan, Kerguelen Island (Sarà et al. 1992).

4B). Microscleres are abundantly scattered all over the choanosome.Spicules: Megascleres: Smooth, slightly curved styles (Fig. 4C). Rare subtylostyles. They measure 325 (407.5) 437.5 x 12 (14) 15 µm. Anisotylotes are straight or slightly sinuous, with swollen and microspined extremities (Fig. 4D). They measure 225 (250) 275 x 6 µm. Microscleres: Spatuliferous anchorate isochelas 1, with three teeth, slightly curved (Fig. 4E). They measure 24 (35.4) 40 µm. Spatuliferous anchorate

Fig. 3: A. Specimen of Pseudosuberites cf. antarcticus Carter, 1876; the arrow points the thin membrane; B. Ectosomal skeleton; C. Choanosomal skeleton; D, F, H. Heads of tylostyles; E. Tip of a tylostyle; G. Subtylostyle.

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Fig. 4: A. Specimen of Myxilla (Myxilla) mollis Ridley and Dendy, 1886; B. Choanosomal skeleton; C. Smooth style; D. Anisotylote; E. Spatuliferous anchorate isochela 1; F. Spatuliferous anchorate isochela 2; G. Sigma 1; H. Sigma 1 and 2 (arrow).

Remarks: This specimen has entirely smooth styles as originally described by Ridley and Dendy (1886) and two categories of sigmas and isochelas as reported by Desqueyroux-Faúndez and van Soest (1996).

Genus Stelodoryx Topsent, 1904

Stelodoryx argentinae sp. nov.

Examined material: OB-4-05: cañon 4 Holotype MSNG 54057Comparative material: holotype of Myxilla cribrigera Ridley and Dendy 1886, Natural History Museum, London (‘Challenger’ coll. BMNH: 87.5.2.138.)

The species consists of a single specimen about 6.5 cm long, massive, with an irregular surface (Fig. 5A). Some oscules, slightly elevated (0.5-1 mm), 1-2 mm in diameter are visible. The consistency is soft and elastic when alive, fragile and friable in the dried state. The colour is black in alcohol and dried. The sponge includes a large amount of sand.Skeleton: The ectosomal skeleton consists of brushes of anisostrongyles with spined ends (Fig. 5B). A thin tangential, dermal membrane is present (Fig. 5B). The choanosomal skeleton (Fig. 5C) is a paucispicular reticulum of main styles, thin styles and anchorate chelae. Spicules: Megascleres are smooth styles (Fig. 5D), straight or slightly curved with acerate or conical tips; they measure 287.5 (351) 412.5 x 10 (13) 15 µm. Straight, thin styles are 188.7 (220.5) 260 x 2.6 µm (Fig. 5E). Straight anisostrongyles (Fig. 5F), with finely spined extremities (Fig, 5G, H); the

diameter of the spicule decreases from an extremity to the other. They measure 209 (240) 262.5 x 5 (7.8) 10 µm. Microscleres are polydentate, spatuliferous isochelae (Fig. 5I) with five teeth. They measure 40.8 (52.4) 65 µm. A few unguiferous anchorate isochelae are present (Fig. 5J). Etymology: The name of this species refers to the sea of origin.Remarks: Among the 11 known species of Stelodoryx, S. cribrigera (Ridley and Dendy, 1886), reported also for the Malvinas Islands is very close to the specimen described here. The study of the holotype of S. cribrigera has shown some differences: the species of Ridley and Dendy is characterized by tylotornotes with slight swelling on the tips. Our species has anisostrongyles with different tips, never swollen. Moreover the species of Ridley and Dendy has larger styles (650 x 25 µm) and lacks thin styles. In the skeleton preparation of the holotype an ectosomal layer of isochelas is evident (also reported by Desqueyroux-Faúndez and van Soest (1996) from additional material), but it is not present in our species.

Family Tedaniidae Ridley and Dendy, 1886Genus Tedania Gray, 1867

Subgenus Tedaniopsis Dendy, 1924

Tedania (Tedaniopsis) charcoti Topsent, 1907

Examined material: OB-4-05: cañon 1Massive sponge with conulose surface, uneven and with

numerous oscules evident. The sponge is soft and brownish in alcohol (Fig. 6A).

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Fig. 5: A. Stelodoryx argentinae sp. nov.: Holotype; B. Ectosomal skeleton; the arrow points the thin dermal membrane; C. Choanosomal skeleton; D. Smooth style; E. Thin style; F. Straight anisostrongyle; G, H. tips of an anisostrongyle; I. Spatuliferous anchorate isochela 1; J. Unguiferous anchorate isochela 2.

Skeleton: Ectosomal skeleton consists of tangentially disposed anisotornotes which form a loose reticulum. The choanosome is an irregular and confused reticulation of longitudinal tracts of styles, and free onychaetes (Fig. 6B).

Spicules: Megascleres are smooth styles, slightly curved (Fig. 6C). They measure 412.5 (432) 462.5 x 10 µm. Smooth, mucronate, straight anisotornotes (Fig. 6D). They measure 262.5 (292) 312.5 x 5 µm. Microscleres (Fig. 6E): Onychaetes

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Fig. 6: A. Specimen of Tedania (Tedaniopsis) charcoti Topsent, 1907; B. Choanosomal skeleton; C. Smooth style; D. Anisotornotes; E. Onychaetes 1 and onychaetes 2.

1 measure 200 (278.6) 462.5 x 2 µm. Onychaetes 2 measure 50 (56.6) 60 µm.Distribution: Antarctic shores, South Georgia, South Sandwich, South Orkney, Strait of Magellan; Kerguelen and Malvinas Islands (Sarà et al. 1992). Argentine Sea (Mar del Plata), Chile (Desqueyroux and Moyano 1987, Cuartas 1992b). South Shetland Islands (Ríos et al. 2004).Remarks: This is a very common species frequently collected in the area. In Desqueyroux-Faúndez and van Soest (1996), this species is well described. Our material fits very well with the description provided by these authors.

Tedania (Tedaniopsis) massa Ridley and Dendy, 1886

Examined material: OB-4-05: cañon 11, cañon 13The specimen consists of two small fragments of a massive, lobose sponge (Fig. 7A). The surface is irregular and minutely hispid. The consistency is soft. The colour is beige.

Skeleton: In the ectosome tornotes project towards the surface in divergent brushes (Fig. 7B). The choanosome is a loose reticulum of styles and fibres of onychaetes. These run to the surface, anastomosing and connecting to secondary fibres.Spicules: Megascleres are smooth styles slightly to strongly curved (Fig. 7C). They measure 400 (440) 500 x 15 (16) 20 µm. Mucronate anisotornotes are 287.5 (373) 500 x 10 µm (Fig. 7D). Microscleres (Fig. 7E): Onychaetes 1 measure 437.5 (480) 660 µm. Onychaetes 2 measure 45 (67.8) 85 µm.Distribution: South Atlantic Ocean: from Uruguay to the Strait of Magellan, Argentina (Mar del Plata) (Mothes and Pauls 1979, Cuartas 1992b, 1992c). Antarctic shores, South Georgia, Malvinas Islands (Sarà et al. 1992).

Tedania (Tedaniopsis) sarai sp. nov.

Examined material: OB-4-05: cañon 8; Holotype MSNG 54058

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Comparative material: holotype of Tedania armata Sarà, 1978, Museo Civico di Storia Naturale G. Doria of Genoa (Ant. 3’). Specimen of Tedania lanceta Koltun, 1964, identified by V. M. Koltun; pictures of spicules of the specimen labelled NN 6767 and NN 6751 as the type material is missing.

This species is massive, cavernous with a smooth, uneven surface (Fig. 8A). The consistency is hard. The colour is brown in alcohol, dirty grey in the dried state, clearer in the interior. Skeleton: In the ectosome anisotornotes make tangential surface tracts. The choanosome is a reticulation of smooth styles (Fig. 8B).Spicules: Megascleres: Curved, often slightly flexuous styles (Fig. 8C), with frequent lanceolate or abruptly pointed tips (Fig. 8D). The heads of the styles are elongated, blunt (Fig. 8E). The thickness of the shaft is often reduced below the elongated extremity of the style. Measurements 387.6 (430.9) 469 x 10.4 (12.3) 13 µm. Straight or slightly curved, anisotornotes, with lanceolate, slightly inflated extremities (Fig. 8F, G). They measure 275.4 (319.3) 375 x 5.2 (6.8) 7.8 µm. Microscleres: onychaetes 1 (Fig. 8H) with short spines (Fig. 8I); they measure 387.6 (434.4) 489.6 x 2.6 µm; onychaetes 2 with different extremities (Fig. 8J) and longer spines (Fig. 8K); they measure 44 (63.7) 122 x 1 µm.Etymology: Named after the late Prof. Michele Sarà for his contribution to the knowledge of Porifera in general,

including an important contribution towards Argentine sponge taxonomy.Remarks: This species is very close to T. (Tedaniopsis) lanceta Koltun, 1964 and to T. armata Sarà, 1978. Koltun’s species differs in having stouter styles (400-480 µm long and 16-22 µm wide) that are not flexuous and have lanceolate tips. In the description of Koltun (1964) the anisotornotes are thicker (360-400 µm long and 14-16 µm wide), and moreover onychates 1 are shorter (270-320 µm long). The holotype is missing so any direct comparison is not possible. Thanks to Dr. Alexander Ereskovsky (St. Petersburg State University, Russia) we had the possibility to compare the spicule complement of this species with some pictures of spicules of T. lanceta Koltun, 1964, determined by Koltun. This comparison confirmed the previous observed differences. Moreover the shape of the spicules of this specimen seems different from our species: the extremities of the anisotornotes are often asymmetrical and bent.

Tedania armata Sarà, 1978 was synonymised with T. charcoti by Desqueyroux-Faúndez and van Soest (1996), but the authors gave no reason for this decision. We suggest the synonymy between T. armata and T. charcoti should be reconsidered on the basis of the examined material and on our experience dealing with antarctic and subantarctic sponges. Tedania charcoti has in fact true styles while in T. armata these principal spicules are subtylostyles with long and acuminate tips (Fig. 9), and also the tornotes are different from those of T. charcoti that have mucronate tips (see e.g.

Fig. 7: A. Fragments of Tedania (Tedaniopsis) massa Ridley and Dendy, 1886; B. Ectosomal skeleton made of tornotes in divergent brushes (arrow) and loose reticulum of styles of the choanosome; C. Smooth style; D. Mucronate anisotornotes; E. Onychaetes 1 and onychaetes 2.

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Fig. 8: Tedania (Tedaniopsis) sarai sp. nov.: Holotype; B. Choanosomal skeleton; C. Style; D. Magnification of an abruptly pointed tip of the style; E. Magnification of the blunt head of the style; F. Lanceolate anisotornotes; G. Magnification of the lanceolate tip of the anisotornotes; H. Onychaetes 1; I. Magnification of onychaetes 1; J. Onychaetes 2; K. Magnification of onychaetes 2.

Desqueyroux-Faúndez and van Soest (1996), Figs. 107-110, page 57).

Comparison with the holotype of T. armata (Fig. 9A) illustrates the primary differences between this species and T. sarai sp. nov.: in T. armata the principal spicules are subtylostyles with rounded heads (Fig. 9B, C, D), while the tips are similar to those of T. sarai sp. nov. (Fig. 9B). In T. armata numerous styles modified to oxeas (Fig. 9D) and

expanded just before the distal tip, rendering the spicule lance-like (lanceolated, Fig. 9B) are common. The dimensions of the styles are also different: in T. armata these spicules are shorter and thinner (300-350 x 6-8 µm, Sarà (1978); 308-372 x 8 µm, Desqueyroux-Faúndez and van Soest (1996)). Tornotes have rounded, and mucronate tips in T. armata (Fig. 9E-H), while in our species they have lanceolate tips. The dimensions of

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Fig. 9: A. Tedania armata. Sarà, 1978: Holotype (Ant 3’); B. Subtylostyle; C. Heads of subtylostyles; D. Style modified in oxea; E, F. Tornotes with rounded tips; G. Magnification of a tip of a tornote; H. Anisotornote with mucronate and rounded tips; I. Onychaete.

Fig. 10: A. Specimen of Tedania (Trachytedania) mucosa Thiele, 1905; B. Loose reticulation of tracts of styles and abundant onychaetes of the choanosomal skeleton; C. Smooth style; D. Mucronate tornote; E. Onychaetes 1 and onychaetes 2.

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the tornotes in T. armata are also smaller. Onychaetes 1 in T. sarai sp. nov. are longer: 150-180 µm (Fig. 9I).

Subgenus Trachytedania Ridley, 1881

Tedania (Trachytedania) mucosa Thiele, 1905

Examined material: OB-4-05: cañon 5The sponge is massive, irregularly elongate. Surface

uneven with scattered oscules (Fig. 10A). The consistency is hard, the colour light brown.Skeleton: The ectosome is a perpendicular palisade of densely arranged mucronate tornotes. The choanosomal skeleton is a loose reticulation of tracts of styles and abundant onychaetes (Fig. 10B).Spicules: Megascleres are smooth, slightly curved styles (Fig. 10C). They measure 250 (266.5) 287.5 x 12 (13) 15 µm. Mucronate tornotes (Fig. 9D) measure 200 (215) 245 x 6 µm. Microscleres (Fig. 10E): Onychaetes 1 measure 135 (186.5) 210 µm; onychaetes 2 measure 40.8 (54) 71 µm.Distribution: Malvinas Islands, Chilean coast (Desqueyroux 1972). Argentina, Mar del Plata (Cuartas 1992b, Desqueyroux-Faúndez and van Soest 1996); Strait of Magellan (Sarà et al. 1992). Remarks: Two kinds of onychaetes are present as reported by Desqueyroux-Faúndez and van Soest (1996).

Suborder Mycalina Hajdu, van Soest and Hooper, 1994Family Guitarridae Dendy, 1924

Genus Guitarra Carter, 1874

Guitarra dendyi (Kirkpatrick, 1907)

Examined material: OB-4-05: cañon 2Massive, cushion-shaped sponge with uneven surface

(Fig. 11A). The consistency is soft and in alcohol the colour is brick red. Skeleton: In the ectosome the skeleton is made of exotyles arranged in bouquets with apices pointing toward the surface of the body and scattered sigmas. In the choanosome strongyles are irregularly arranged.Spicules: Megascleres are rare exotyles with a spherical, wrinkled apex and a rounded base (Fig. 11B). They measure 210 (300) 400 x 10 (15) 20 µm; head diameter measures 50 (65) 80 µm. Straight anisostrongyles (Fig. 11C). They measure 375 (454.5) 512.5 x 6 (8) 9 µm. Microscleres: placochelae (Fig. 11C-F); they measure 75 (84.5) 90 µm. C-shaped sigma. They measure 10 (12) 15 µm. Distribution: Antarctic shores and South Shetland Islands (Ríos et al. 2004).Remarks: This is the first record of Guitarra dendyi for the Argentine Sea. The distribution of this species was limited to the Antarctic shores (Wilhem II Coast, Banzare Coast, Victoria Land) (Ríos et al. 2004) and to the South Shetland

Islands, therefore its geographical range is considerably extended northwards.

Discussion

Among the nine species collected, only one (Tedania charcoti) was previously found associated with Patagonian scallop beds (Schejter et al. 2006). The present findings, including two species new for science, suggest the importance to continue the study of these deep areas, still widely unexplored. Our results extend the geographical range northwards for Pseudosuberites cf. antarcticus and Guitarra dendyi, for which species these are the first records outside the Antarctic sea.

The lack of data on deep-water faunas around Antarctica has been recently highlighted by Brandt et al. (2007). These Authors evidenced how the abyssal Antarctic fauna has strong links with others oceans, mainly Atlantic, but only when taxa are good dispersers. For example, isopods, ostracods and nematodes include many species known exclusively in Antarctica differently from the foraminifera.

In this way our results suggest once again the importance to study these environments to better evaluate also the relative importance of dispersal by larvae or by floating propagules (as suggested by Burton 1932) to account for a possible relationship between sponge distribution and oceanic current systems. Although not as deep as the community described by Brandt et al. (2007), there are just few studies of the Argentinian Sea waters of subantarctic origin in the continental shelf, the shelf break and submarine canyons. The Argentinian side of the Magellanic Biogeographic Province is influenced by the Malvinas Current, a relatively fresh and cold branch of the Circumpolar Current, strongly flowing northward along the continental shelf of Argentina (Garzoli 1993, Piola and Rivas 1997, Vivier and Provost 1999). However, based on evidence from faunal analysis done in the study area and also considering the shelters and dead shells found by Bremec et al. (2006), it is possible that important fluxes from the shelves to deeper oceanic waters were performed throughout submarine canyons.

Fishing effort can produce several ecological consequences, for instance changes in species richness and biodiversity, loss of erect and fragile epifauna, widely damaging epibiotic community (Turner et al. 1999, Coleman and Williams 2002, Thrush and Dayton 2002). Sponges are frequently collected in the invertebrate by-catch of the Patagonian scallop fishery in the neighbouring shelf of the study area and represented approximately 5–10% of total community biomass (Bremec et al. 1998, 2000, Bremec and Lasta 2002, Schejter et al. 2006). Porifera biomass at Patagonian scallop beds in the Argentine Sea decreased between 1995 and 1998 in exploited areas (Bremec et al. 2000). Between 1998 and 2001, the sponge contribution in these areas represented an average of 0.3 kg / 100 m2 (wet weight) (Schejter 2004). It will be interesting to know if a long term consequence of the fishing activity will

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be, owing to sponge fragmentation caused by trawling, the increase in the distribution of some sponge species in respect to other species on intermediately deep Argentinian bottoms.

Acknowledgments

We thank A. Madirolas and G. Alvarez Colombo (Hydroacoustics Lab., I.N.I.D.E.P. Argentina) for the information and images of the Canyon and Maurizio Pansini (Dip. Te. Ris, Genoa University) for his helpful suggestions. The authors are indebted to Dr. Alexander

Ereskovsky (St. Petersburg State University, Russia) for sending us V.M. Koltun’s material for comparison.

References

Boury-Esnault N (1973) Campagne de la “Calypso” au large des côtes atlantiques de l’Amérique du Sud (1961-1962). 29. Spongiaires. Rés Sci Camp Calypso 10: 263-295

Brandt A, Gooday AJ, Brandão SN, Brix S, Brökeland W, Cedhagen T, Choudhury M, Cornelius N, Danis B, De Mesel I, Diaz RJ,

Fig. 11: A. Specimen of Guitarra dendyi (Kirkpatrick, 1907); B. Light microscopy observation of an exotyle; C. Anisostrongyle and placochela (arrow); D, E, F. Placochelae.

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Gillan DC, Ebbe B, Howe JA, Janussen D, Kaiser S, Linse K, Malyutina M, Pawlowski J, Raupach M, Vanreusel A (2007) First insights into the biodiversity and biogeography of the Southern Ocean deep sea. Nature 447: 307-311

Bremec CS, Lasta ML (2002) Epibenthic assemblage associated with scallop (Zygochlamys patagonica) beds in the Argentinian shelf. Bull Mar Sci 70(1): 89-105

Bremec C, Lasta M, Lucifora L, Valero J (1998) Análisis de la captura incidental asociada a la pesquería de vieira patagónica (Zygochlamys patagonica (King and Broderip 1832)). Inf Técn INIDEP 22: 1-18

Bremec C, Brey T, Lasta M, Valero J, Lucifora L (2000) Zygochlamys patagonica beds on the Argentinian shelf: Part I: Energy flow through the scallop bed community. Arch Fish Mar Res 48(3): 295-303

Bremec C, Schejter L, Madirolas A, Tripode M (2006) Comunidades de aguas profundas: macrofauna bentónica de un cañón submarino localizado en la plataforma patagónica (43º35’S, 59º33’W). VI Jornadas Nacionales de Ciencias del Mar, Puerto Madryn, Argentina. Book of abstracts. p. 128

Burton M (1932) Sponges. Discov Rep 6: 237-392Carter HJ (1876) Descriptions and figures of deep-sea sponge and

their spicules from the Atlantic ocean, dredged up on board HMS “Porcupina” Chiefly in 1869 (concluded). Ann Mag Nat Hist, ser. 4, 20: 38-42

Coleman FC, Williams SL (2002) Overexploiting marine ecosystem engineers: potencial consequences for biodiversity. Trends Ecol Evol 17: 40-44

Cuartas EI (1986) Poríferos de la Provincia Biogeográfica Argentina. Physis A 44 (106): 37-41

Cuartas EI (1991) Demospongiae (Porifera) de Mar del Plata (Argentina) con la descripción de Cliona lisa sp. n. y Plicatellopsis reptans sp. n. Neritica 6(1-2): 43-63

Cuartas EI (1992a) Poríferos intermareales de San Antonio Oeste, provincia de Río Negro, Argentina (Porifera: Demospongiae). Neotropica 38(100): 111-118

Cuartas EI (1992b) Poríferos de la Provincia Biogeográfica Argentina. III. Poecilosclerida (Demospongiae) del litoral marplatense. Physis A 47 (113): 73-88

Cuartas EI (1992c) Algunas Demospongiae (Porifera) de Mar del Plata, Argentina, con descripción de Axociella marplatensis sp. n. Iheringia Sér Zool 73: 3-12

Cuartas EI (1995) Redescripción de Clathria burtoni “nomen novum” de C. prolifera Burton, 1940. (Porifera: Demospongiae). Ann Mus Civ St Nat “G. Doria” XC: 571-576

Desqueyroux R (1972) Demospongiae (Porifera) de la costa de Chile. Gayana Zool 20: 1-71

Desqueyroux-Faúndez R (1989) Demospongiae (Porífera) del litoral chileno antártico. Ser Cient Inach 39: 97-158

Desqueyroux-Faúndez R, Moyano HI (1987) Zoogeografía de Demospongias chilenas. Bol Soc Biol Concepción (Chile) 58: 39-66

Desqueyroux-Faúndez R, van Soest RWM (1996) A review of Iophonidae, Myxillidae and Tedaniidae occurring in the south east Pacific (Porifera: Poecilosclerida). Rev Suisse Zool 103: 3-79

Garzoli SL (1993) Geostrophic velocity and transport variability in the Brazil-Malvinas confluence. Deep Sea Res 40: 1379-1403

Koltun VM (1964) Sponges of the Antarctic. I. Tetraxonida and Cornacuspongida. In: Pavlovskii EP, Andriyashev AP, Ushakov PV (eds). Biol Rep Soviet Antarct Exped (1955-1958), Akademya Nauk SSSR [English translation, 1966, Israel Program for Scientific Translations]. Vol. 2 (10). S. Monson, Jerusalem. pp. 6-133, 443-448

Mothes-de-Moraes B, Pauls SM (1979) Algunas esponjas monaxonidas (Porifera: Demospongiae) do litoral sul do Brasil, Uruguay e Argentina. Iheringia Sér Zool 54: 57-66

Parker G, Paterlini MC, Violante RA (1997) El fondo marino. In: Boschi E (ed). El mar argentino y sus recursos pesqueros, I. antecedentes históricos de las exploraciones en el mar y las características ambientales. pp. 65-87

Piola AR, Rivas AL (1991) Corrientes en la plataforma continental. Mar Arg Rec Pesq 1: 119-132

Ridley S, Dendy A (1886) Preliminary report on the Monaxonida collected by H.M.S. ‘Challenger’. Part I and II. Ann Mag Nat Hist 18(5): 325-351, 470-493

Ridley S, Dendy A (1887) Report on the monaxonida collected by H.M.S. ‘Challenger’ during the year 1873-1876. Rep Sci Res Voy H.M.S. ‘Challenger’, Zool 20: 1-275

Ríos P, Cristobo FJ, Urgorri V (2004) Poecilosclerida (Porifera, Demospongiae) collected by the Spanish Antarctic expedition BENTART-94. Cah Biol Mar 45: 97-119

Sarà M (1978) Demospongie di acque superficiali della Terra del Fuoco (Spedizioni A.M.F.Mares-G.R.S.T.S. e S.A.I). Boll Mus I Biol Univ Genova 46: 7-117

Sarà M, Balduzzi A, Barbieri M, Bavestrello G, Burlando B (1992) Biogeographic traits and checklist of Antarctic demosponges. Polar Biol 12: 559-585

Schejter L (2004) Estructura comunitaria en un banco de vieira patagónica Zygochlamys patagonica (Mollusca: Bivalvia: Pectinidae) sujeto a arrastres pesqueros, Mar Argentino. MSc Thesis. Universidad Internacional de Andalucía, Baeza

Schejter L, Calcinai B, Cerrano C, Bertolino M, Pansini M, Giberto D, Bremec C (2006) Porifera from the Argentina Sea: diversity in Patagonian scallop beds. Ital J Zool 73 (4): 373-385

Schulze FE (1887) Report on the Hexactinellida collected by H.M.S. ‘Challenger’ during the years 1873-76. Rep Sci Res Voy H.M.S. ‘Challenger’, Zool 21: 1-513

Sollas WJ (1886) Preliminary account of the Tetractinellid sponges dredged by H.M.S. ‘Challenger’ 1872-76. Part I. The Choristida. Scient Proc R Dubl Soc 5: 177-199

Sollas WJ (1888) Report on the Tetractinellida collected by H.M.S. ‘Challenger’ during the years 1873-76. Rep Sci Res Voy H.M.S. ‘Challenger’, Zool 25: 1-458

Thrush SF, Dayton PK (2002) Disturbance to marine benthic habitats by trawling and dredging: implications for marine biodiversity. Ann Rev Ecol Syst 33: 449-473

Topsent E (1902) Spongiaires. Expéd. antarct. belge. Rés Voy S Y Belgica, 1897-1899: 1-54

Turner SJ, Thrush ST, Hewitt JE, Cumming UJ, Funnell G (1999) Fishing impacts and the degradation or loss of habitat structure. Fish Manag Ecol 6: 401-420

Vivier F, Provost C (1999) Direct velocity measurements in the Malvinas Current. J Geophys Res 104: 21083-21103