Obelia longissima (Pallas, 1766)

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, Zootaxa 3171 (1), pp. 1-77 : 51-52

publication ID

https://doi.org/ 10.11646/zootaxa.3171.1.1

DOI

https://doi.org/10.5281/zenodo.5248556

persistent identifier

https://treatment.plazi.org/id/03C8247E-D030-FFBF-FF62-F9E6FC612E77

treatment provided by

Felipe

scientific name

Obelia longissima (Pallas, 1766)
status

 

Obelia longissima (Pallas, 1766) View in CoL

Figs. 54, 55

Sertularia longissima Pallas, 1766: 119 .

Obelia flabellata View in CoL .— Segerstedt, 1889: 12, 25.— Jäderholm, 1909: 62, pl. 5, fig. 16.

Obelia longissima View in CoL .— Jäderholm, 1909: 63, pl. 5, fig. 14.— Östman, 1982a: 156; 1982b: 228; 1983: 7; 1999: 19.—Cornelius, 1990: 559.

Laomedea longissima View in CoL .— 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 GoogleMaps .

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 View FIGURE 55 ), 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).

Kingdom

Animalia

Phylum

Cnidaria

Class

Hydrozoa

Order

Leptothecata

Family

Campanulariidae

Genus

Obelia

Loc

Obelia longissima (Pallas, 1766)

Calder, Dale R. 2012
2012
Loc

Laomedea longissima

Ostman, C. 1979: 6
Jagerskiold, L. A. 1971: 63
1971
Loc

Obelia longissima

Ostman, C. 1999: 19
Ostman, C. 1983: 7
Ostman, C. 1982: 156
Ostman, C. 1982: 228
Jaderholm, E. 1909: 63
1909
Loc

Obelia flabellata

Jaderholm, E. 1909: 62
Segerstedt, M. 1889: 12
1889
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