Candelabrum phrygium Fabricius 1780
Creators: name: Peter Schuchert
name: Nadya Sanamyan
name: Karen Sanamyan
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Cnidaria
Hydrozoa
Anthoathecata
Candelabridae
Candelabrum
Candelabrum phrygium

description: Candelabrum phrygium (Fabricius, 1780)
Figs 4-6, 7 E-F
Lucernaria phrygia Fabricius, 1780: 343.
Myriothela arctica M. Sars, 1850: 134.
Myriothela phrygia. – M. Sars, 1877: 23, pl. 2 figs 29-36. ‒ Bonnevie, 1899: 35, pl. 4 figs 5-6. ‒ Jäderholm, 1908: 9, pl. 1 fig. 7. ‒ Broch, 1916: 19, fig. C, pl. 1 figs 3 & 8. ‒ Rees, 1957: 486, fig. 36. ‒ in part Naumov, 1969: 261, not figures [= C. cocksii]. ‒ Calder, 1972: 222, pl. 1 fig. 5.
? Myriothela gigantea Bonnevie, 1898: 490, pl. 27 figs 46-47. ‒ Bonnevie, 1899: 38, pl. 4 fig. 1. ‒ Rees, 1956: 115, synonym.
? Myriothela minuta Bonnevie, 1898: 489, pl. 27 fig. 44. ‒ Bonnevie, 1899: 37, pl. 3 fig. 6a-b, pl. 4 fig. 4. ‒ Rees, 1956: 115, synonym.
? Myriothela mitra Bonnevie, 1898: 489, pl. 27 fig. 43. ‒ Bonnevie, 1899: 38, pl. 3 fig. 6c-e, pl. 4 fig. 3. ‒ Rees, 1956: 115, synonym.
Myriothela verrucosa Bonnevie, 1898: 468, pl. 27 fig. 45. ‒ Bonnevie, 1899: 37, pl. 4, fig. 2 & 2a. ‒ Rees, 1956: 115, synonym.
Candelabrum phrygium – in part Cornelius, 1977: 521 [excl. synonymy]. ‒ Segonzac & Vervoort, 1995: 45, figs 2ef, 3E-F, table 1 [some references do not refer to this species]. ‒ Schuchert, 2001: 37, fig. 24. ‒ Schuchert, 2006: 346, fig. 8. ‒ Antsulevich, 2015: 176, fig. 78A-Б.
not Myriothela phrygia. – Hincks, 1868: 77. – Allman, 1874: 317. ‒ Allman, 1875a: 135. ‒ Allman, 1875b: 250. ‒ Allman, 1875b: 317. ‒ Allman, 1876: 549, pls 55-58. – Hardy, 1891: 505, pls 36-37. – Blackburn, 1899: 58, pl. 8. – Hartlaub, 1916: 110, figs 38-39. [all = C. cocksii].
? not Candelabrum verrucosum. ‒ Schuchert, 2006: 349, fig. 9.
Material examined
Type material:
Candelabrum verrucosum, UZMO B1376a through B 1376g; 7 slides with serial histological sections, labelled “ Myriothela verrucosa ”, from the Norwegian North-Atlantic Expedition. No locality data given. Bonnevie (1899) gives Hammerfest as origin, depth unknown.
Kamchatka material:
MHNG-INVE-92005, field number Kam01; 4 specimens in ethanol, male and female individuals; Russia, Kamchatka Peninsula, Avacha Bay, Starichkov Island, 52.77457°N 158.611517°E, 23 m depth, temperature 0°C; collection date 13.09.2010.
MHNG-INVE-92006, field number Kam02, 3 female specimens in ethanol; Russia, Kamchatka Peninsula, Avacha Bay, Starichkov Island, 52.77457°N 158.611517°E, 23 m depth, temperature 0°C; collection date 13.09.2010.
MHNG-INVE-92007, field number Kam03, 8 specimens, male and female individuals in ethanol and serial histological sections of blastostyles of a male and a female individual; Russia, Kamchatka Peninsula, Avacha Bay, Starichkov Island, 52.77457°N 158.611517°E, 22 m depth, temperature 5°C; collection date 27.07.2010; DNA isolate 1120; 16S sequence LN898139.
MHNG-INVE-92008, field number Kam04, 1 male specimen in ethanol; Russia, Kamchatka Peninsula, Avacha Bay, Starichkov Island, 52.774783°N 158.61048°E, 23 m depth, temperature 4°C; collection date 27.07.2010.
MHNG-INVE-92009, field number Kam08, 1 male and 1 female individual in ethanol; Russia, Kamchatka Peninsula, Avacha Bay, Bezimenniy Point, 52.84746°N 158.64323°E, 10 m depth, temperature 5°C; collection date 22.07.2009.
MHNG-INVE-92010, field number Kam09, 1 male specimen in ethanol and serial histological sections of 2 blastostyles; Russia, Kamchatka Peninsula, Avacha Bay, Starichkov Island, 52.77457°N 158.611567°E, 20 m depth, temperature 1°C; collection date 13.09.2010.
MHNG-INVE-92011, field number Kam10, 1 male in ethanol and serial histological sections of blastostyle; Russia, Kamchatka Peninsula, Avacha Bay, Starichkov Island, southern side, 52.77367°N 158.61983°E, 24 m depth, temperature 8°C; collection date 26.09.2010.
MHNG-INVE-92013, field number Kam11, 3-4 immature specimens in ethanol; Russia, Kamchatka Peninsula, Avacha Bay, Starichkov Island, behind Karaulny Kekkur, 52.77925°N 158.62348°E, 14 m depth, temperature 12°C, on the shell of a living gastropod Fusitriton oregonensis; collection date 27.08.2010; DNA isolate 1122; 16S sequence LN898141.
MHNG-INVE-92012, field number Kam12, 1 male specimen in ethanol; Russia, Kamchatka Peninsula, Avacha Bay, Mayachy Point, rock with sand, 52.88687°N 158.69633°E, 8 m depth, collection date 05.06.2014; DNA isolate 1121; 16S sequence LN898140.
Other Candelabrum phrygium material:
ZMUC-HYD-294; between Iceland and Jan Mayen Island, Ingolf station 117, 69.22°N 08.22°W, 1890 m; collection date 14.07.1896; identification P. Kramp; fragments of very large specimens in ethanol, blastostyles with relatively long tentacles, female sporosacs seen, sessile, without nematocyst buttons.
ZMUC-HYD-295; Greenland; identified by Lütken, collection date unknown; samples mentioned in Schuchert (2006); 2 female specimens in ethanol and serial histological sections of blastostyles; body size 1-2 cm, rarely nematocyst buttons seen on some sporosacs.
ZMUC-HYD-296; Greenland; much fragmented and not well preserved specimen in ethanol, presumably male, some sporosacs with nematocyst buttons perhaps present.
ZMUC-HYD-297; north of Iceland, Ingolf Station 125, 68.13°N 16.03°W, 1373 m; collection date 29.07.1896; identified by H. Broch; 2 cm specimen in ethanol, blastostyles with tentacles but no sporosacs.
ZMUC-HYD-298; Greenland, Skovfjord, 10-35 m depth; collection date 05.09.1912; identified by P. Kramp; 1 nice specimen on red algae in ethanol, presumably male, some sporosacs with few nematocyst buttons.
ZMUC-HYD-299; between Iceland and Jan Mayen Island; Ingolf station 117, 69.22°N 08.22°W, depth 1890 m; collection date 14.07.1896; identification H. Broch; several black fragments in ethanol, female sporosac seen, no nematocyst buttons.
ZMUC-HYD-300; Greenland, Kap Farvel station 145, 60.07°N 43.20°W, depth 100 m; collection date 27.8.1970; 5 mm specimen in ethanol, juvenile, young sporosacs with or without nematocyst buttons, identity unclear.
Material of previously identified as Candelabrum verrucosum:
ZMUC-HYD-301; southernmost region of Greenland, Kap Farvel Expedition station 148, 60.07°N 43.20°W, 50 m depth; collection date 28.08.1970; 1 cm specimen in ethanol and serial histological sections of blastostyle (Fig. 7 C-D), hermaphrodite; sporosacs with up to 10 nematocyst buttons [material mentioned in Schuchert (2006) as Candelabrum verrucosum].
Comparison material of Candelabrum cocksii:
MHNG-INVE-36299, 1 specimen in ethanol and histological sections of blastostyles. (see Schuchert, 2006: 341); France, Brittany, Roscoff, 48.73°N 4.00°W, 0 m depth; collection date 17.09.2004.
Type locality: Greenland (Fabricius, 1780).
Diagnosis: Solitary species of Candelabrum with polyps 1-10 cm or more in height when reproductive. Basal foot zone relatively short or absent, straight, not sheathed in envelope of perisarc, attached to substratum by tentacle-like filaments, filaments with or without terminal perisarc discs. Numerous blastostyles in part above foot and under tentacle zone, relatively long, 5 mm or more, straight, not branched, with very short capitate tentacles in distal third, often reduced to mere nematocyst buttons; clasper tentacles absent; sporosacs developing in epidermis, without peduncle and thus sessile. Individuals gonochoristic, females viviparous. Distal tentacle zone long and very extensible, with hundreds of short capitate tentacles.
Description of Kamchatka material
Morphology: Polyps solitary, vermiform, size highly variable in being able to expand and contract enormously. Hydranth shape also variable, usually cylindrical to conical, subdivided into distal tentaculate region (trunk), followed by blastostyle region and sometimes also a short foot zone. Foot zone either very short in relation to other parts or absent, not curved, adhering to substratum by several tentacle-like attachment filaments, each with terminal sucker-like ending, the latter sometimes with a disc of perisarc that adheres to substratum, but perisarc discs often absent.
Blastostyle region about 1/4 to 1/3 length of polyp (Fig. 4A), beset by many (>20) simple club-shaped, unbranched blastostyles. Distal end of blastostyles with four to six nematocyst clusters in wart-like tubercles, number and distribution very variable. Mature blastostyles bearing spherical to hemispherical sporosacs lacking a pedicel, hence sessile (Fig. 5 D). Male sporosacs without radial canals, up to 25 per blastostyle at different developmental stages. Female polyps with up to 12 sporosacs per blastostyle, sporosacs without radial canals, eggs fertilized in situ and developing into young polyps, hence viviparous (Fig. 5 A, 7C). On surface of sporosacs 1-20 nematocyst buttons, some sporosacs without buttons. All examined polyps unisexual.
Trunk region comprising majority of hydranth length, with numerous (>200) capitate tentacles, these hollow, extensible, capitula oblong.
Dimensions: 1-20 cm in height (maximal size only in situ and when fully expanded), preserved material difficult to assess due to strong contractibility. Blastostyles 5 mm long. Male sporosacs about 0.4-0.5 mm, female sporosacs up to 0.9 mm,
Colours: cream-white, pinkish or orange-yellow.
Nematocysts of preserved animals: stenoteles (Fig. 6 A), of two size classes, (12.5-16)x(8.5-13.5)μm; small desmonemes (Fig. 6 B), (8-9.5)x(5.5-6)μm; large desmonemes (Fig. 6 C-D), (14.5-16)x(9-12.5)μm, discharged filament with 5-6 coils; microbasic euryteles with distinctly swollen shaft, shaft somewhat longer than capsule when discharged (Fig. 6 E-F), (15-22)x(5.5-8) μm.
Distribution: An Arctic species penetrating into Boreal regions, in the Atlantic waters reaching as far south as the Trondheimfjord (shallow waters) and in deep waters south-west of the Azores (Schuchert, 2006). It has also been recorded in the Russian Arctic seas and the northern Pacific (Paramushir Island, south of Kamchatka Peninsula; Naumov, 1969). (Note that numerous other records under this name from coastal regions of the NE Atlantic refer actually to Candelabrum cocksii; see Schuchert, 2006.)
Biology: Occurs usually at considerable depths of several hundreds of meters down to 2195 m (Bonnevie, 1899), but in the high Arctic it has been found as shallow as 13 m (Jäderholm, 1908). The current findings from Kamchatka confirm that it also occurs in shallow (8-23 m) depths.
The polyps live permanently attached to solid substrata like rock, bivalves, hydroids, bryozoans, and algae. The present material was found on stones and frequently on the bryozoan Myriopora orientalis (Fig. 4B). Two young specimens (Kam11) were found on the shell of a living gastropod Fusitriton oregonensis (Redfield).
Like other Candelabrum species, C. phrygium is viviparous and lacks a planula phase (Sars, 1877; Schuchert, 2006). The newly released polyp is spherical and has 20-30 capitate tentacles. The tentacles formed while the embryos is still in the sporosac develop inverted into the gastric lumen (Fig. 5 A), but they revert to the outside before hatching (comp. Allman, 1876; Schuchert, 2006).
Remarks: All Candelabrum species have been reviewed by Segonzac & Vervoort (1995), but many remain difficult to separate if no biogeographic information is considered. The Kamchatka material conforms well to existing descriptions of the Arctic Candelabrum phrygium (e. g. Segonzac & Vervoort, 1995; Schuchert, 2006), except for the presence of nematocyst buttons on the sporosacs (Figs 4C, 5B-C). These buttons occur in variable numbers from 1 to 20 per sporosac, and occasional sporosacs also lack them. The presence of such nematocyst buttons has been deemed diagnostic for the species Candelabrum verrucosum (Bonnevie, 1898) (Segonzac & Vervoort, 1995; Schuchert, 2006), but a re-evaluation is necessary. Candelabrum verrucosum is a very rare, poorly described species. After examining the type material, Rees (1956) considered it conspecific with C. phrygium. Segonzac & Vervoort (1995) kept it distinct, but had no new material. The only specimen-based record of C. verrucosum after the first description was that of Schuchert (2006). The identification of his Greenland specimen relied on the presence of nematocyst buttons, which were presumed to be diagnostic for the species. The simultaneous presence of both male and female sporosacs (Fig. 7C) distinguished the sample clearly from the C. phrygium, which is gonochoristic (Segonzac & Vervoort, 1995).
However, the identity of C. verrucosum warrants reappraisal. Bonnevie’s (1898) description of the species was cursory, and suitable illustrations were not provided. Bonnevie mentioned the presence of flat radial canals in the gonophores, which would be quite unusual for the genus (comp. Briggs, 1928, 1929, 1931; Manton, 1940). Moreover, there was a small gastrodermal vesicle (depicted in Bonnevie, 1899: pl. 4 fig. 2a) under the nematocyst buttons of young sporosacs in Bonnevie’s material, something never seen in the present material and also not observed in the material of Schuchert (2006; see Fig. 7 C-D). Another error in the original description seems likely, as Bonnevie (1898) stated that the essential diagnostic trait of the species was the existence of nematocyst buttons on the blastostyle, while in the preceding paragraph she described them as being on the gonophores. In the following section she described more histological details, but referred to the blastostyle instead of a gonophore. In order to get a clearer picture, it was thus necessary to re-examine the type material of C. verrucosum, obtained on loan from the Natural History Museum of Oslo University. The type material was not labelled as such, but there can be no doubt that this is what remains from the holotype of C. verrucosum. The material is apparently from the “N. Nordhavsekspedition” and is clearly labelled as Myriothela verrucosa; moreover, Bonnevie (1898) stated that she made histological sections. The material consists of seven microscope slides with stained, serial histological sections. The slides are marked with a letter ranging from a through g. The tissues are not well preserved, something already deplored by Bonnevie (1898: 487), and it takes some effort to identify what is present on the slides (Fig. 7E). The presence of the tentacle zone in the last slides and the presence of a prey item in the gastric system permit an identification and orientation of the sectioned parts. Slides a-f contain horizontal sections of the whole polyp ranging from the blastostyle region (Fig. 7E) to the beginning of the tentacle zone. Slide g, in contrast, contains serial longitudinal sections of a blastostyle with two sporosacs. The slides allow corrections and additions to be made to Bonnevie’s account:
- there is no evidence of male sporosacs; all appear to be female, the most advanced containing a young polyp with inverted tentacles, so the animal is thus likely gonochoristic.
- there are only very few nematocyst buttons on the sporosacs (Fig. 7G) and there is no gastrodermal vesicle below it. The situation is identical to that seen in the new material (Fig. 5 C).
- sporosacs have no radial canals or any vestiges of them.
- the nematocyst buttons and the underlying “small gastrodermal vesicle” depicted in Bonnevie (1899: pl. 4 fig. 2a; here 7F) most likely represent a small tentacle on the blastostyle (the “small gastrodermal vesicle” is in fact the lumen of the tentacle). The vesicles definitely do not occur on mature sporosacs (Fig. 7G).
From a re-examination of the type material of C. verrucosum and other historical material of C. phrygium, we conclude that there is no evidence to warrant separation of the two species. As already concluded by Rees (1957), C. verrucosum must be regarded as a synonym of C. phrygium.
Re-examination of material of C. phrygium from the ZUMC revealed that historical samples of the species (see material examined) may also have occasional nematocyst buttons on the sporosacs, but never as many as seen in some females of specimens from Kamchatka. The sole presence of these nematocyst buttons is thus not diagnostic for C. verrucosum. The possible developmental origin of nematocyst buttons in Kamchatka material is also important in this context. The gonophores develop from cell aggregations at the base of the epidermis as described for C. penola by Manton (1940: fig. 3). In contrast to C. cocksii (Fig 7 A-B), no stalk develops and the sporosacs remain sessile (Fig. 5 B-D) while the original blastostyle epidermis stretches over them. The blastostyles may also bear at their end short capitate tentacles or mere nematocyst buttons (comp. Fig. 4A or Schuchert, 2006: fig. 8B). These tentacle rudiments may end up on the surface of a growing sporosac, possibly explaining their occasional presence. However, the large numbers seen here (e. g. Fig. 4C) are clearly an additional development. Although certainly not enough material has been examined for a well-founded conclusion, it is interesting to note that only colonies from shallow waters (7-50 m) had numerous buttons, while deep water specimens had none or only a few. This can of course also be used as an argument to separate the two groups into two distinct species, but we prefer to think that the number of nematocyst buttons is environmentally related, e. g. induced by unspecific predators/browsers like nudibranchs, which are presumably more abundant in shallow waters. We therefore consider the presence of nematocyst buttons alone as insufficient justification to regard C. verrucosum as distinct, and the Kamchatka material is assigned to C. phrygium. The high number of nematocyst buttons on female sporosacs is here considered to constitute intraspecific variation or to be environmentally induced. Moreover, Candelabrum phrygium has already been recorded from the region by Naumov (1969, Paramushir Island).
If presence of nematocyst buttons on the sporosacs is insufficient basis to distinguish C. verrucosum as a valid species, then the identification of Schuchert (2006) of a Greenland specimen as C. verrucosum has to be revised. This material is clearly hermaphroditic (Fig. 7C) and thus different from all known samples of C. phrygium. So far, only two hermaphroditic species of Candelabrum are known, namely C. cocksii and C. serpentarii Segonzac & Vervoort, 1995. Candelabrum cocksii is a distinct species, easily separable by its characteristic clasper tentacles which hold the encapsulated developing embryos (Schuchert, 2006). Candelabrum serpentarii, on the other hand, differs only from C. phrygium in being hermaphroditic (Segonzac & Vervoort, 1995). Note that size differences in Candelabrum are of minor importance as reproductive animals can vary in size by an order of magnitude (e. g. C. penola, Manton, 1940). Likewise, the nematocyst types are rather uniform and any observed differences are of little use for the few, allopatric specimens that are available. Photographs of the type specimen of C. serpentarii, kindly provided by Dr A. Andouche (Muséum National d’Histoire Naturelle, Paris), showed no evidence of nematocyst buttons. Some of the sporosacs contain young polyps, while others are smaller and opaque. Without histological sections it is impossible to determine their sex. Segonzac & Vervoort (1995) apparently did not make histological sections, and their interpretation that the animal is hermaphroditic needs reconfirmation. Nevertheless, it could be that also hermaphroditism is part of the intraspecific variability of C. phrygium (perhaps it is a sequential hermaphrodite) and this has not been seen due to the small number of specimens examined histologically.
To clarify species limits within the genus Candelabrum, and to settle the identity of specimens examined here, more samples of these rare species are needed and additional molecular genetic analyses must be undertaken. The three 16S sequences of the Kamchatka material obtained here are minimally different, and BLAST searches in GenBank (results not shown) gave as the closest match Candelabrum austrogeorgiae (accession number FN424120). Unfortunately, insufficient data are currently available from other species for a more detailed taxonomic assessment.
description: Published as part of Peter Schuchert, Nadya Sanamyan & Karen Sanamyan, 2016, Observations on two large athecate hydroids (Cnidaria: Hydrozoa) from the Kamchatka Peninsula (NW Pacific), pp. 165-178 in Revue suisse de Zoologie 123 (1) on pages 170-177, DOI: 10.5281/zenodo.46301