Jan 28, 2009 - Alectonidae) boring into Japanese precious coral, Italian Journal of Zoology, 71:4, ... as the shaft, so that the whole forms an eight-rayed star.
Italian Journal of Zoology
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Redescription of Alectona verticillata (Johnson) (Porifera, Alectonidae) boring into Japanese precious coral Barbara Calcinai , Francesca Azzini , Giorgio Bavestrello , Nozomu Iwasaki & Carlo Cerrano To cite this article: Barbara Calcinai , Francesca Azzini , Giorgio Bavestrello , Nozomu Iwasaki & Carlo Cerrano (2004) Redescription of Alectona verticillata (Johnson) (Porifera, Alectonidae) boring into Japanese precious coral, Italian Journal of Zoology, 71:4, 337-339, DOI: 10.1080/11250000409356592 To link to this article: http://dx.doi.org/10.1080/11250000409356592
Published online: 28 Jan 2009.
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Date: 28 January 2016, At: 20:22
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Ital. J. Zool., 71: 337-339 (2004)
Redescription of Alectona verticillata (Johnson) (Porifera, Alectonidae) boring into Japanese precious coral BARBARA CALCINAI FRANCESCA AZZINI GIORGIO BAVESTRELLO Dipartimento di Scienze del Mare, Università Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy)
NOZOMU IWASAKI Usa Marine Biological Institute, Kochi University, Usa-cho, Tosa, Kochi 781-1164 (Japan)
CARLO CERRANO
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Dip. Te. Ris., Università di Genova, Corso Europa 26, I-16132 Genova (Italy)
ABSTRACT The boring sponge Alectona (Nisella) verticillata (Johnson, 1899) was recorded, for the first time after the description, in a colony of Corallium elatius collected in the south of the Ryukyu Islands (Japan Sea). The material recorded allowed a redescription of the species based on the SEM analyses of its spicular complement. Alectona verticillata is the only species of the genus characterised by three kinds of amphiasters and by the lack of the large, spiny or tubercolate diactines, considered typical of the genus. Its distribution recalls the Tethyan distribution of the genus Corallium, indicating a high specificity of boring sponges for their substrata. KEY WORDS: Alectona - Boring sponges - Precious coral - Pacific Ocean.
ACKNOWLEDGMENTS The Authors wish to thank SNK Ocean Co., Ltd, Mr. Kazuhiko Ueno of the All Japan Coral Fishing Manager of Association and Mr. Masaki Kikuchi of the Sukumo Precious Coral Cooperative for providing the studied material. (Received 22 December 2003 - Accepted 28 April 2004)
INTRODUCTION In 1899, Johnson published a paper with the description of five new species of boring sponges recorded on bivalves and "various corals brought up by lines of fishermen from deep water off the coast of Madeira". In spite of its small size (three pages and one plate), the paper is important because the Author established in it three new genera of boring sponges: Acca, Scantilla and Nisella, dedicated to personages of the ancient Roman literature. The last of Johnson's genera was erected for the species N. verticillata, boring the carbonatic skeletons of colonies of the precious coral Corallium johnsoni Gray, I860 and of the madreporian coral Dendrophyllia ramea (Linnaeus, 1758). According to the Author, the spicular complement of the species is composed by two kinds of amphiasters. "The most abundant is normally a slender straight shaft, from the middle of which radiate six equally slender arms, which are half as long as the shaft, so that the whole forms an eight-rayed star. [...] The second form of spicule is a fusiform shaft with two whorls of three short rays each at the middle." He also published a clear picture of the spicules from which it is possible to estimate a size ranging from 60 to 75 pm. No macroscleres were described. Johnson remarked that the nodulose amphiasters are of the same kind as those described by Carter (1879) in Alectona millari. On the basis of these amphiasters, recently Rützler (2002) considered Nisella as a junior synonymous of Alectona. After its first record in 1899, A. verticillata was never found again but, recently, while examining the sponges boring the scleraxis of precious coral from Okinawa, Japan Sea, we recorded it for the second time. This material allowed us to provide a new description of this rare species based on the SEM analyses of the spicules and to establish a neotype, as Johnson's type material is missing (Rützler, 2002).
MATERIALS AND METHODS The material derives from a colony of Corallium elatius (commercial name "Pink corals") collected off Ishigaki and Iriomote Islands, in the southern Ryukyu Islands (Japan Sea) by the Fishing company SNK Ocean Co., Ltd. The colony was collected at 195-300 m depth by the ROV "Hakuyo 2000". The studied material consists in a flat portion (25 x 20 mm) of tissue inside a large cavity at the basis of a large coral colony (Fig. 1). Spicule preparations were made by dissolving pieces of sponges in boiling nitric acid, and after rinsing in water and ethanol, mounting spicules on microscope slides. The same preparation was followed for the scanning electron microscope observation. In this case, spicules were put on stubs and sputtered with gold.
B. CALCINAI, F. AZZINI, G. BAVESTRELLO, N. IWASAKI, C. CERRANO
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size (up to 8 pm) and not alternatively disposed. Frequently immature forms with conical shaft are present, as long as the previous one but thinner (2.5 pm or less), (b) Slender amphiasters (Fig. 2f-h) with six conical rays in two verticils alternatively disposed. The rays are microspined with spined concentrated on the extremities, 15-30 pm long, 23.2 pm long on average and 2.5 pm wide. Immature forms, with thin and slightly spined or almost smooth rays, are common, (c) Small amphiasters (Fig. 2i-k), 7.5-13 pm long, with a short axis and twelve spined rays, organized in two verticils alternatively disposed. The conical spines bent towards the centre of the spicules are preferentially concentrated at the extremities where they form a knob. In the sponge choanosome, the spicules are organized without any particular orientation, forming a tangential, compact stratum. CONCLUSIVE REMARKS Fig. 1 - Basal portion of Corallium elatiiis excavated by A. verticillata (arrow). The smaller signs of erosion are probably made by an Aka species. Scale bar, 2 cm.
TAXONOMINC ACCOUNTS Family ALECTONIDAE Genus Alectona Carter, 1879
Up to date, nine Alectona species are known.- A wallichii (Carter, 1874), A. millari Carter, 1879, A. triradiata Lévi & Lévi, 1983, A. primitiva Topsent, 1932, A. jamaicensis Pang, 1979, A. sorrentini Bavestrello et al., 1998, A. microspiculata Bavestrello et al., 1998, A. mesatlantica Vacelet, 1999, and A. verticillata (Johnson, 1899). The characteristics of the spicular complement of our material are so peculiar that the identification with A. (TV.) verticillata appears certain: spicules are only amphiasters and no megascleres (diactines and poly-
Alectona verticillata (Johnson, 1899) Material Neotype material: (Museo di Storia Naturale di Genova) MSNG 51936, portion of sponge tissue. Several slides in the Authors' collection.
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Description The sponge, dark brown in colour (dried), occupied a large cavity of about 20 x 25 mm in diameter in a large basal portion about 6 cm in diameter of C. elatius (Fig. 1). Papillae, connecting the sponge choanosome with the exterior, are not visible. In the same substrate, other macroscopic signs of erosion are present (Fig. 1). It was not possible to examine them, but the finding of oxeas suggests that they could be due to an Aka species. Spicules: amphiasters of three kinds, (a) Fusiform amphiasters (Fig. 2a-e) with the shaft minutely spined 32.5-70 x 3.7-7.5 urn; 58.6 x 5.7 pm on average. The width of the shaft decreases toward the extremities that are slightly swollen and sometimes bears an apical spine. From the middle of these spicules, two rings of six spined tubercles, alternatively disposed, arise. The organisation of the tubercles is sometimes untidy: they may be different in number (five or seven), longer in
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Fig. 2 - Alectona verticillata spicules. a-e, fusiform amphiasters; fh, slender amphiasters with six conical rays. Scale bars, 20 urn; ik, small amphiasters. Scale bars, 5 pm.
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REDESCRIPTION OF ALECTONA VERTÏCILLATA
actines) are present. Shape and size of the two kinds of large amphiasters are the same as in Johnson's species, but in the Japanese sample a further category of small amphiasters, not reported by the Author, is present. These spicules are not rare, but very small and could have been overlooked in the original description. Other species of Alectona, A. triradiata and A. microspiculata, have two kinds of amphiasters, but A. verticillata is the only species with three kinds of microscleres. This fact, together with the lack of megascleres, makes this species perfectly distinguishable inside the genus. Following the definition of the genus Alectona given by Rützler (2002), in A. verticillata the robust megascleres (diactines and polyactine) should be considered lost. The distribution of A. verticillata recalls the Tethyan distribution of the genus Corallium comprising, besides the Mediterranean, both the Atlantic and the Pacific area (Bayer, 1961; Bayer, 1964; Castro et al., 2003). A similar distribution is also typical of the genus Spiroxya (= Scantilettd), a boring genus always recorded inside the scleraxis of precious corals (Calcinai et al., 2002), indicating a marked specificity of boring sponges for their substrata (Bavestrello et al., 1998).
REFERENCES Bavestrello G., Calcinai, B., Cerrano C., Sarà M., 1998 - Alectona species from North-West Pacific (Demospongiae: Clionidae). J. Mar. Biol. Ass. U.K., 78: 59-73. Bayer F. M., 1961 - The shallow-water Octocorallia of the West Indian Region. A manual for marine biologists. Martinus Nijhoff, The Hague. Bayer F. M., 1964 - The genus Corallium (Gorgonacea: Scleraxonia) in the western North Atlantic Ocean. Bull. Mar. Sci. Gulf Caribb, 14: 465-478. Calcinai B., Cerrano C., Bavestrello G., 2002 - A new species of Scantiletta (Demospongiae, Clionaidae) from the Mediterranean precious red coral with some remarks on the genus. Bull. Mar. Sci., 70: 919-926. Carter H. J., 1879 - On a new species of excavating sponge (Alectona millari); and on a new species of Raphidotheca (R. affinis). J. R. Microsc. Soc, 5: 493-499. Castro C. B., Thiago C. M., Medeiros M. S., 2003 - First record of the family Coralliidae (Cnidaria: Anthozoa: Octocorallia) from the western South Atlantic, with a description of Corallium medea Bayer, 1964. Zootaxa, 323: 1-8. Johnson J. Y., 1899 - Notes on some s belonging to the Clionidae obtained at Madeira. J. R. Microsc. Soc, 10: 461-463. Rützler K., 2002 - Family Clionaidae D'Orbigny, 1851. In: J. N. A. Hooper & R. W. M. van Soest (eds), Systema Porifera. Kluger Academic/Plenum Publisher, New York, pp. 173-185.
