Obelia longissima

• Main Author: Calder, Dale R.
• Format: Text
• Language: unknown
• Published: Zenodo 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Hydrozoa; Leptothecata; Campanulariidae; Obelia; Obelia longissima; Arctic; Canada; Greenland; Norway; Sven; Gronland; Atlantic Arctic; Atlantic-Arctic; Iceland; North Atlantic
• Online Access: https://dx.doi.org/10.5281/zenodo.5248555; https://zenodo.org/record/5248555

Obelia longissima (Pallas, 1766) Figs. 54, 55 Sertularia longissima Pallas, 1766: 119. Obelia flabellata .— Segerstedt, 1889: 12, 25.— Jäderholm, 1909: 62, pl. 5, fig. 16. Obelia longissima .— Jäderholm, 1909: 63, pl. 5, fig. 14.— Östman, 1982a: 156; 1982b: 228; 1983: 7; 1999: 19.—Cornelius, 1990: 559. Laomedea longissima .— Jägerskiöld, 1971: 63.— Östman, 1979a: 6. Type locality. “Oceanus Europaeus” (Pallas 1766: 120). Museum material. Tjärnö, floating dock at Sven Lovén Centre for Marine Sciences, 58°52’33.68”N, 11°08’43.65”E, <1 m, 07.ix.2010, collected manually from dock, one colony, 9.5 cm high, without gonothecae, ROMIZ B3889. Remarks. The validity of Obelia longissima (Pallas, 1766) was confirmed by Östman (1982a, b, 1987, 1999), who showed that it differed from O. dichotoma (Linnaeus, 1758) in cnidome and in acid phosphatase band patterns. According to Cornelius (1990, 1995), O. longissima can be distinguished from O. dichotoma in having: (1) long, monosiphonic, regularly branched stems that are often dark or even black in colour; (2) branches over a given part of the stem of essentially the same length; (3) hydrothecae round instead of polygonal in cross-section; (4) hydrothecal margin with shallow, wavy cusps rather than a series of lobes. Nevertheless, young, old, or damaged specimens can still be difficult to identify based on morphology alone. The colonies examined here, rather old, somewhat damaged, and overgrown with other hydroids, corresponded most closely to O. longissima . Examination of nematocysts from tissue of museum material (ROMIZ B3889) revealed the presence of F l - type isorhizas (Fig. 55b, c), diagnostic of the species (Östman 1982b). A-type b-rhabdoids (microbasic b-mastigophores) were also present. A comprehensive overview of this species was given by Cornelius (1990). It is frequent in Danish waters (Kramp 1935b, as Laomedea longissima ) and in the Oslofjord, Norway (Christiansen 1972), as well as western Sweden (Jägerskiöld 1971). Reported distribution. West coast of Sweden.—From Strömstad area to south of Falkenberg (Jägerskiöld 1971: 63). Elsewhere.—North Atlantic-Arctic from polar waters to the Mediterranean Sea in Europe, and to South Carolina in North America (Schuchert 2001a; Bouillon et al . 2004; Calder 2004). : Published as part of Calder, Dale R., 2012, On a collection of hydroids (Cnidaria, Hydrozoa, Hydroidolina) from the west coast of Sweden, with a checklist of species from the region 3171, pp. 1-77 in Zootaxa 3171 (1) on pages 51-52, DOI: 10.11646/zootaxa.3171.1.1, http://zenodo.org/record/5247704 : {"references": ["Segerstedt, M. (1889) Bidrag till kannedomen om hydroid-faunan vid Sveriges vestkust. Bihang till Kongliga Svenska Vetenskaps-Akademiens Handlingar, 14, Afdelning 4, 4, 1 - 28.", "Jaderholm, E. 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Acta Regiae Societatis Scientiarum et Litterarum Gothobergensis, Zoologica, 6, 1 - 146.", "Ostman, C. (1979 a) Two types of nematocysts in Campanulariidae (Cnidaria, Hydrozoa) studied by light and scanning electron microscopy. Zoologica Scripta, 8, 5 - 12.", "Linnaeus, C. (1758) Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. Laurentii Salvii, Holmiae, 823 pp.", "Kramp, P. L. (1935 b) Polypdyr (Coelenterata) I. Ferskvandspolypper og goplepolypper. Danmarks Fauna, 41, 1 - 207.", "Christiansen, B. O. (1972) The hydroid fauna of the Oslo Fiord in Norway. Norwegian Journal of Zoology, 20, 279 - 310.", "Schuchert, P. (2001 a) Hydroids of Greenland and Iceland (Cnidaria, Hydrozoa). Meddelelser om Gronland, Bioscience, 53, 1 - 184.", "Bouillon, J., Medel, M. D., Pages, F., Gili, J. - M., Boero, F. & Gravili, C. (2004) Fauna of the Mediterranean Hydrozoa. Scientia Marina, 68 (Suppl. 2), 5 - 438.", "Calder, D. R. (2004) Subtidal hydroids (Cnidaria) of Northumberland Strait, Atlantic Canada, with observations on their life cycles and distributions. Canadian Field-Naturalist, 117, 555 - 564. (Although dated 2003, this article did not appear until 2004)."]}