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A new Mediterranean species of Tethya (Porifera: Tethyida: Demospongiae) a
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G. Corriero , F. Gadaleta & G. Bavestrello a
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Department of Biology, University of Bari, Via Orabona 4, 70126, Bari, Italy
b
Department of Biology, University of Genova, Corso Europa 26, 16132, Genova, Italy Published online: 17 Aug 2015.
Click for updates To cite this article: G. Corriero, F. Gadaleta & G. Bavestrello (2015): A new Mediterranean species of Tethya (Porifera: Tethyida: Demospongiae), Italian Journal of Zoology, DOI: 10.1080/11250003.2015.1077278 To link to this article: http://dx.doi.org/10.1080/11250003.2015.1077278
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Italian Journal of Zoology, 2015, 1–9 http://dx.doi.org/10.1080/11250003.2015.1077278
A new Mediterranean species of Tethya (Porifera: Tethyida: Demospongiae)
G. CORRIERO1, F. GADALETA1, & G. BAVESTRELLO2* 1
Department of Biology, University of Bari, Via Orabona 4, 70126, Bari, Italy, and 2Department of Biology, University of Genova, Corso Europa 26, 16132, Genova, Italy
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(Received 15 March 2015; accepted 2 July 2015)
Abstract A new species of Tethya, T. meloni, is described from the Mediterranean Sea. The sponge, spherical in shape, displays a large size, up to about 8 cm in diameter. The surface is pale yellow, covered by flattened tubercles. It differs from the known Mediterranean Tethya species (T. citrina and T. aurantium) according to the following traits: larger body size; colour; shape and size of megasters; distribution pattern of micrasters. Keywords: Tethya, Demospongiae, Porifera, Mediterranean Sea
Introduction
Materials and methods
Tethya Lamarck, 1815 is a widely distributed, cosmopolitan demosponge genus, with a peculiar spherical shape and a fibrous cortex distinct from the choanosome, allowing an easy separation from the other genera of the family Tethyidae (Sarà 2002). The main skeleton is formed by megasclere bundles, radiating from the centre of the sponge. Microscleres are divided into megasters and micrasters, which are variously distributed in the ectosome and choanosome (Hooper 1997). Tethya is the most speciose genus of its family (Sarà 2002), with 91 valid species described around the world (Van Soest et al. 2015). Two species of this genus, sometimes sympatrically living, are reported from the Mediterranean Sea: Tethya aurantium, the type species of the genus described by Pallas (1766), and T. citrina (Sarà & Melone 1965). The present paper describes a new species of Tethya, T. meloni, and focuses on interspecific affinities and differences within the Mediterranean species of this genus. The data here reported, referred to different sites of the Mediterranean Sea, also enlarge the present knowledge of the geographic distribution of this genus.
Samples come from extensive collections specifically directed towards the study of the Mediterranean species of Tethya. Samples from shallow waters were carried out by SCUBA diving while deep samples were mainly obtained by the MEDITS survey programme (International bottom trawl survey in the Mediterranean) carried out in summer 2012 and 2013, at a depth ranging from 60 to 123 m. Sampled specimens were preserved in 80% ethanol. Spicule preparations and skeletal sections were made using classical procedures for Demospongiae (Hajdu et al. 2011). For each studied specimen, 50 spicules from each category were measured. Resinembedded transverse body sections were prepared to examine the skeletal architecture under a light microscope, while micraster ultrastructure was studied under scanning electron microscopy (SEM; HITACHI TM-3000) to observe details of their ornamentation. The type and paratypes of Tethya meloni sp. nov. are deposited in the Museum of Zoology (Biology Department) of Bari University, Italy. The terminology used for the spicular traits follows Sarà (1994).
*Correspondence: G. Bavestrello, Department of Biology, University of Genova, Corso Europa 26, 16132, Genova, Italy. Tel: +39 010 3538031. Fax: +39 010 352169. Email:
[email protected] © 2015 Unione Zoologica Italiana
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Taxonomic accounts SYSTEMATICS Class DEMOSPONGIAE Order TETHYIDA Morrow & Cárdenas (2015) Family TETHYIDAE Gray, 1848 Genus Tethya Lamarck, 1815 (Figures 1–7, Tables I–II)
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Type material Holotype. Mar Piccolo di Taranto, SW Apulia, July 2012, June 2013, 1 – 3 m depth, by SCUBA (40° 30ʹ07.17ʹ’N, 17°15ʹ47.61ʹ’E). Paratypes: Stagnone of Marsala, NW Sicily, July 2013, 0.2–1.5 m of depth, by SCUBA (37°51ʹ51.17ʹ’N, 12°28ʹ12.96ʹ’E); Porto Cesareo, SW Apulia, July 2012 and August 2013, 2 m depth, by SCUBA (40°15ʹ13.14ʹ’N, 17°54ʹ51.72ʹ’E); Manfredonia, June 2013, N Apulia, 2–5 m depth, by SCUBA (41°37ʹ45.65ʹ’N, 15°57ʹ02.12ʹ’E); off Vajussa – Albania, July 2012, 115–123 m depth, by bottom trawl; off Zvernec – Albania, July 2012, 87 m depth, by bottom trawl; off Sazan, Albania, July 2012, 106 m depth, by bottom trawl; off Bar, Albania, July 2012, 76–77 m depth, by bottom trawl; off Porto Badisco, July 2013, S Apulia, 57 m depth, by bottom trawl; off Isola of Elba, July 2012, Tuscany Archipelago, 106 m depth, by bottom trawl;
Tyrrhenian Sea (off Genova), July 2012, 120 m depth, by bottom trawl; Venice, June 2012, 24 m depth, by SCUBA (45°10ʹ42.56ʹ’N, 12°16ʹ05.25ʹ’E).
Description All of the examined specimens exhibit a spherical shape (Figure 2), with an in vivo diameter varying from 2.9 to 7.6 cm. The sponge body is clearly divided into a fibrous cortex surrounding the choanosome (Figure 2C). The cortex, 0.3–0.5 cm in thickness, is well developed and may represent up to 1/3 of the sponge diameter (Figure 2C). The colour of living specimens varies from cream to pale yellow, whereas it is green–brown inside. Surface with flattened or scarcely prominent tubercles (Figure 2B). Consistency moderately hard and compressible. A circular, large osculum (about 0.5 cm in diameter), well visible in vivo (Figure 2B), usually occurs in each specimen.
Skeleton The main skeleton is formed by bundles of strongyloxeas radiating from the centre of the sponge (Figures 3, 4A); auxilary strongyloxeas occur. The megasters (oxyspheraster; Figure 4B–D) are evenly and densely distributed throughout the whole cortex,
Figure 1. Tethya meloni sp. nov. (triangles). Coastal sampling sites. Circles and squares indicate the areas of occurrence of T. aurantium and T. citrina, respectively.
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Figure 2. Tethya meloni sp. nov.: A–B, Detail of specimens in vivo; C, dissected specimen with well developed cortex; D, facies formed by several specimens at Taranto. Scale bars: A, 4 cm; B, 2 cm; C, 2.5 cm; D, 5 cm.
Figure 3. Tethya meloni sp. nov. Schematic drawing of the skeletal structure.
scattered in the choanosome. Micrasters form a thin external cortical layer (Figure 4A) and are also scattered through the sponge tissue (Figure 4B). They do not show differences in shape between cortical and choanosomal regions.
Spicules Large strongyloxeas (Figure 5), 730–1890 µm in length (mean size: 1310 µm), 10–40 µm in thickness (mean size: 25 µm). Auxilary strongyloxeas (Figure 5), 340–840 µm in length (mean size:
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Figure 4. Tethya meloni sp. nov. A, cortical region, with bundles of strongyloxeas, oxyspherasters scattered through the sponge tissue and the layer of superficial oxyasters; B, choanosomal (lower) and cortical (upper) regions of the sponge, with several oxyspherasters.
Figure 5. Tethya meloni sp. nov. Strongyloxeas. Scale bars: A, 200 µm; B, D 30 µm; C, E 300 µm; F, 20 µm.
Figure 6. Tethya meloni sp. nov. Megasters. Scale bars: A–D, F, 10 µm. E, 20 µm.
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Figure 7. Tethya meloni sp. nov. Micrasters. Scale bar: 10 µm.
590 µm) and 8–10 µm in thickness (mean size: 9 µm). Oxyspherasters (Figures 4B–D, 6) 65.7– 119 µm in diameter, with 12–16 rays slightly curved towards the tip and sometimes bifurcated (mean size: 90 ± 14 µm); R/C (ratio of ray length/centrum diameter) = 1–1.8 (mean value 1.4 ± 0.3; Tables I, II). Micrasters (Figure 7) are heterogeneous in shape, although falling into two categories: chiasters–tylasters and oxyasters, which differ in the shape of the rays (conical or cylindrical). Spines, from small to large, perpendicular to the ray, often present only at the tips. The size of micrasters (diameter) ranges from 13.7 to 14.9 µm (mean size: 14 ± 2 µm) in the cortex and from 15 to 17.4 µm (mean size: 16 ±2.4 µm) in the choanosome (Table I). Ecological and biological features At Taranto, Tethya meloni mainly colonises vertical artificial substrates (pools for mussel farming, artificial piers) not directly exposed to sunlight, where it forms large facies (Figure 2D), with very high density values (up to about 100 specimens per square metre of substrate). In this site the species coexists with
T. citrina, which usually occurs in more shallow waters (from 1 m depth up to a few centimetres over the low-tide level), mainly under rocky stones (Figure 1; Cardone et al. 2010). At Marsala (Figure 1), T. meloni colonises shaded rocky substrates. In this lagoon all three Mediterranean species coexist, with rare cases of overlap in the spatial distribution between T. meloni and T. aurantium. Here, T. aurantium and T. citrina display the same habitat preference, since both are preferentially associated to the rhizome layer of the phanerogam Posidonia oceanica (Corriero et al. 1989). At Porto Cesareo, T. meloni lives in non-sessile habitus, over soft bottoms covered by the seagrass Cymodocea nodosa. The sponge colonises a lightexposed habitat, and its external surface appears partially covered by a thick layer of the red alga Rytiphloea tinctoria which entraps moderate amounts of fine sediment (Figure 2A). In this site T. aurantium also occurs, but it constantly shows a sessile habitus and its spatial distribution does not overlap with that of T. meloni. At Manfredonia, T. meloni lives on shaded, vertical artificial walls, in a condition very similar to that displayed at Taranto.
Marsala
P. Cesareo
P. Badisco
Manfredonia
Bar
Vajussa
Zvernec
Sazan (Albania)
Tyrrhenian Tuscany Sea Aechipelago
Venice
SD, standard deviation. *R/C is the ratio between the length of the ray and the diameter of the centre of the spicule (mean ± SD).
Number of specimens 20 20 20 1 10 10 2 1 2 2 1 2 Strongyloxeas min-max 420–1900 340–1250 480–1830 930–1710 500–1480 550–2100 580–1850 880–1540 540–1820 550–1650 410–1480 570–1530 length (μm) min–max 9–40 10–20 10–35 15–25 10–35 10–30 10–30 15–20 10–35 10–30 10–25 10–25 width (μm) Megasters (mean 96 ± 18.1 76.5 ± 12.6 103 ± 16 119 ± 10.5 91.3 ± 11.6 91.8 ± 19.6 106 ± 14.5 90.08 ± 9.8 81.5 ± 12.9 65.7 ± 15.1 67.6 ± 13.8 92.9 ± 13.6 diameter ± SD) *Megasters (average 1 ± 0.2 1.3 ± 0.2 1.2 ± 0.2 1.8 ± 0.2 1.4 ± 0.2 1.8 ± 0.4 1.2 ± 0.3 1.7 ± 0.2 1.7 ± 0.4 1.6 ± 0.4 1.2 ± 0.3 1.3 ± 0.3 R/C ± SD) 13.±1.4 13.7 ± 2.2 13.8 ± 1.9 13.4 ± 1.6 13.2 ± 1.6 14.9 ± 2.4 14.6 ± 2.5 14.9 ± 1.9 14.5 ± 1.5 13.9 ± 1.7 14 ± 1.8 15 ± 2.3 *Cortical micrasters (average R/C ± SD) *Choanosomal 15 ± 1.9 15.8 ± 2.3 15.2 ± 2.2 15.4 ± 2.0 15.5 ± 2.1 17.4 ± 3 16 ± 2.5 15.9 ± 2.9 16.3 ± 2.5 16.1 ± 1.5 15.9 ± 3 16.3 ± 1.1 micrasters (average R/C ± SD)
Taranto
Table I. Tethya meloni sp. nov. Spicule size (µm) at different sampling sites.
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Table II. Size values and morphological traits referred to 166 specimens of Tethya aurantium, 215 specimens of T. citrina (from Sarà 1985, modified) and 89 of T. meloni sp. nov. (present paper). Characters
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Sponge diameter Cortex thickness Cortex structure Surface Colour Megaster shape Megaster size (diameter) Ray length/centrum Rays, number Micrasters
T. aurantium
T. citrina
T. meloni
10.0–45.5 mm (30.5 mm) 1.5–3.5 mm (2.6 mm) Thick collagenous layer Papillate Red–orange Spherasters 16.2–93.6 μm (53.6 μm) 0.4–0.8 (0.5) 21–30 (25) Two categories: (1) cortical, variable from oxyaster, chiaster to tylaster, 10–15 μm (12 μm); (2) choanosomal, oxyaster, 18–21 μm (20 μm)
5.5–26.0 mm (15 mm) 1.0–1.5 mm (1.2 mm) Thin collagenous layer Smooth or conulose Yellowish or greenish Oxyspherasters 18.0–64.8 μm (42.9 μm) 0.6–1.4 (1.1) 10–20 (15) One category variable from oxyaster, chiaster to tylaster, both in cortex and choanosome, 10–15 μm (12 μm)
29–76 mm (52 mm) 3–5 mm (4 mm) Thick collagenous layer Flattened tubercles Cream Oxyspherasters 65.7–119.0 μm (89.8 μm) 1–1.8 (1.4) 12–16 (14) One category variable from oxyaster, chiaster to tylaster, both in cortex and choanosome. Different size between cortical, (13.7–14.9 μm (14 μm)) and choanosomal (15–17.4 μm (16 μm)) tissue Uncommon 1.5–4.0 mm 2
Asexual reproduction Common Bud size (diameter) 1.5–4.0 mm Maximum number of buds 55 per specimen
Ecological information on deep records of T. meloni is gathered by the observation of remotely operated vehicle (ROV) images. They are available exclusively for the Isola of Elba (Tuscany archipelago, 106 m depth; F. Cardone and S. Canese pers. comm.). In this locality the sea bottom is characterised by the presence of numerous small calcareous concretions (up to several metres high), surrounded by mud. Sponges are among the most abundant organisms associated with the coral gardens, and largely cover the substrate under the cnidarian ramifications or encrust the dead portions of their skeletons. At the Isola of Elba, T. meloni colonises the horizontal surfaces of concretions and can reach density values up to five specimens per square metre. In the ROV images, the numerous specimens observed appear constantly covered by a thick layer of fine sediment. Out of 89 specimens of T. meloni sampled in total, only two budding specimens were detected. By contrast, asexual budding was usually observed in the coexisting T. aurantium and T. citrina through the sampling period (summer) at Taranto, Porto Cesareo and Marsala. Moreover, literature data confirm the high frequency of asexual budding events in many Mediterranean populations of the latter two species (T. aurantium and T. citrina) (Corriero et al. 1996, 2007; Gaino et al. 2006; Cardone et al. 2010). Buds detected from T. meloni are similar in shape and size to those produced by T. aurantium (Table II).
Common 0.25–1.0 mm 250
Etymology The specific name is given in honor of Prof. Nicola Melone, for his contribution to the taxonomy of Mediterranean Tethyidae.
Conclusive remarks Tethya meloni sp. nov. resembles the Mediterranean T. aurantium in its large body size and well developed cortex. In both species, the external and thick cortex is characterised by large and flattened tubercles. However, the largest size reported for specimens of T. aurantium ranged between 4.5 (Sarà & Melone 1965) and 5.5 cm in diameter (Corriero et al. 1989), whereas T. meloni shows maximum diameter values around 8 cm (Table II). In comparison with T. citrina, the new species shows similarities in the colour of the surface (grey to yellow in T. citrina, cream in T. meloni) and in the main spicular traits. In particular, T. meloni and T. citrina share the same type of megaster (oxyspheraster) and micrasters (a mix of oxyasters, chiasters and tylasters). However, oxyspherasters in T. meloni are larger (65.7–119 µm in diameter; mean value: 90 ± 14 µm) compared to T. citrina (from 18.0 to 64.8 µm; mean value: 42.9 µm; Sarà 1985). In both species oxyspherasters are characterised by long rays, with highest values of R/C index (ray length and centre diameter) in T. meloni
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(from 1–1.8), with respect to T. citrina (0.6–1.4; Sarà 1985). Microscleres are also similar in shape and size in both species (Sarà 1985). However, no differences in the distribution of such spicules through the sponge skeleton are reported in the literature for T. citrina. In addition, in T. meloni, choanosomal oxyasters are larger than the corresponding cortical ones (Table II). Thereafter, whereas the external morphological traits of the new species are closer to those of T. aurantium, the spiculation pattern of T. meloni displays more affinity with T. citrina. The new species shows a wide distribution through the Italian coast, both in shallow and deep (around −100 m) waters. The low number of shallow records for the west side of the Italian peninsula probably reflects the lack of suitable sites and habitats. Indeed, in shallow waters T. meloni is closely associated to sheltered environments (mainly semienclosed, no brackish environments), where it constantly coexists with either or both of the congeneric species T. aurantium and T. citrina. In cases of cooccurrence, however, the species of Tethya usually exhibit a distinct spatial distribution and different microhabitats (Corriero et al. 1989). A remarkable feature is the non-sessile lifestyle observed in T. meloni at Porto Cesareo, a trait previously described at Marsala and Porto Cesareo also for the demosponge Geodia cydonium (Mercurio et al. 2006). However, while in G. cydonium non-sessile specimens coexisted with sessile ones, the latter representing the largest portion of the population, in the specimens of T. meloni from Porto Cesareo the nonsessile condition represents the exclusive lifestyle. The species here described appears very similar to specimens recorded in Limsky Canal (northeast Adriatic) and determined as T. citrina, although characterised by an unusual large diameter and thick cortex (Bavestrello & Sarà 1994). The description of this new species is in agreement with genetic data suggesting a high genetic uniformity of T. aurantium at the Mediterranean Sea scale, while T. citrina is probably composed by different sibling species (Sarà et al. 1989).
Acknowledgements We thank COISPA tecnologia e ricerca, and in particular Dr. P. Carbonara for the collection of deep sponge samples and Dr. Rocco Labadessa for the drawing of T. meloni made by observations with an optical microscope. Special thanks to Nino Trotti (Faculty of Agriculture, University of Bari) for SEM and to Dr. Frine Cardone for the ROV images,
the photographs of sponges in vivo and the invaluable support in SCUBA sampling. References Bavestrello G, Sarà M. 1994. A comparison between morphological and genetic data in two species of Tethya (Porifera, Demospongiae). In: Beaumont AR, editor. Genetics and evolution of aquatic organisms. London: Chapman and Hall. pp. 29–40. Cardone F, Gaino E, Corriero G. 2010. The budding process in Tethya citrina Sarà & Melone (Porifera, Demospongiae) and the incidence of post-buds in sponge population maintenance. Journal of Experimental Marine Biology and Ecology 389:93– 100. doi:10.1016/j.jembe.2010.03.012. Corriero G, Balduzzi A, Sarà M. 1989. Ecological differences in the distribution of two Tethya (Porifera, Demospongiae) species coexisting in a Mediterranean coastal lagoon. P.S.Z.N.I. Marine Ecology 10:303–315. doi:10.1111/j.1439-0485.1989. tb00075.x. Corriero G, Longo C, Mercurio M, Marchini A, OcchipintiAmbrogi A. 2007. Porifera and Bryozoa on artificial hard bottoms in the Venice Lagoon: Spatial distribution and temporal changes in the northern basin. Zoological Journal of the Linnean Society 74:21–29. Corriero G, Sarà M, Vaccaro P. 1996. Sexual and asexual reproduction in two species of Tethya (Porifera, Demospongiae) from a Mediterranean coastal lagoon. Marine Ecology 126:175–181. Gaino E, Scalera Liaci L, Sciscioli M, Corriero G. 2006. Investigation of the budding process in Tethya citrina and Tethya aurantium (Porifera, Demospongiae). Zoomorphology 125:87–97. doi:10.1007/s00435-006-0015-z. Hajdu E, Peixinho S, Fernandez JCC. 2011. Esponjas marinhas da Bahia. Guia de campo e laboratório. Rio de Janeiro: Museu Nacional, Serie livros. pp. 1–276. Hooper JNA. 1997. Sponguide. Guide to sponge collection and identification. Available: http://www/qmuseum.qld.gov.au/orga nization/sections/SessileMarineInvertebrates. Mercurio M, Corriero G, Gaino E. 2006. Sessile and non-sessile morphs of Geodia cydonium (Jameson) (Porifera, Demospongiae) in two semi-enclosed Mediterranean bays. Marine Ecology 148:489–501. Morrow C, Cárdenas P. 2015. Proposal for a revised classification of the Demospongiae (Porifera). Frontiers in Zoology 12:7. Pallas PA. 1766. Elenchus zoophytorum sistens generum adumbrationes generaliores et specierum cognitarium succinctas descriptiones cum selectis auctorum synonymis. Amstelaedami: Hagae-Comitum. pp. 451. Sarà M. 1985. Divergence between the sympatric species Tethya aurantium and Tethya citrina and speciation in sponges. In: Rützler K, editor. New perspectives in sponge biology, Proceedings of the 3rd international. Conference of biology of sponges. Washington, DC: Smithsonian Institution Press. pp. 338–343. Sarà M. 1994. A rearrangement of the family Tethyidae (Porifera, Hadromerida) with establishment of new genera and description of two new species. Zoological Journal of the Linnean Society 110:355–371. doi:10.1111/zoj.1994.110.issue-4. Sarà M. 2002. Family Tethyidae Gray 1867. In: Hooper JNA, van Soest RWM, editors. Systema Porifera: a guide to the classification of sponges. New York: Kluwer Academic. pp. 246–272. Sarà M, Melone N. 1965. Una nuova specie del genere Tethya, T. citrina sp. n. del Mediterraneo (Porifera, Demospongiae).
A new Mediterranean species of Tethya
Downloaded by [Giorgio Bavestrello] at 13:20 17 August 2015
Atti della Società Peloritana di Scienze fisiche, matematiche e naturali 11 (suppl):123–138. Sarà M, Mensi P, Manconi R, Bavestrello G, Balletto E. 1989. Genetic variability in Mediterranean populations of Tethya (Porifera, Demospongiae). In: Ryland JS, Tyler PA, editors. Reproduction, genetics and distributions of marine organisms. Fredensborg: Olsen & Olsen. pp. 293–298.
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Van Soest RWM, Boury-Esnault N, Hooper JNA, Rützler K, de Voogd NJ, Alvarez de Glasby B, Hajdu E, Pisera AB, Manconi R, Schoenberg C, Janussen D, Tabachnick KR, Klautau M, Picton B, Kelly M, Vacelet J, Dohrmann M, Díaz MC, Cárdenas P. 2015. World Porifera database. Available: http://www.marinespecies.org/porifera. Accessed Apr 2015 30.
