Edwardsia aff. tuberculata Duben and Koren, 1847

Izumi, Takato & Fujita, Toshihiko, 2019, Two species of Edwardsia having gigantic nematocysts, E. aff. tuberculata and E. alternobomen sp. nov. (Cnidaria; Anthozoa; Actiniaria; Edwardsiidae) from Japan, Zootaxa 4661 (3), pp. 533-544: 535-536

publication ID

https://doi.org/10.11646/zootaxa.4661.3.7

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scientific name

Edwardsia aff. tuberculata Duben and Koren, 1847
status

 

Edwardsia aff. tuberculata Duben and Koren, 1847 

(New Japanese name: oozutsu-mushimodoki-ginchaku)

Figs. 2View FIGURE 2, 4View FIGURE 4; Table 1

Synonymy: see Fautin (2016)

Material examined. NSMT-Co 1654, dissected specimen, histological sections (7 slides), and prepared cnidae (5 slides), November 6, 2014, east of Ogishima Island, Kagawa Pref., Seto Inland Sea (34°24′54′′N, 134°05′30′′E; Fig. 1AView FIGURE 1), 16 m depth, collected by Naoto Jimi. NSMT-Co 1655, histological sections of damaged individuals (3 slides), same date, locality, and collector as NSMT-Co 1654.

External anatomy. Column of contracted specimen 20–25 mm in whole length (25.0 mm in NSMT-Co 1654), and 6–7 mm in width (7 mm in NSMT-Co 1654), swelled by huge nemathybomes, cylinder-like in shape but slightly swollen proximally ( Fig. 2AView FIGURE 2). Body divided into capitulum, scapus and physa; in our specimen, capitulum shrunken in column, invisible. About half of scapus occupied by nemathybomes, remaining half covered with brownishgrey periderm. Nemathybomes extremely large, like papillae, up to 1.5 mm in diameter ( Fig. 2BView FIGURE 2), in eight rows in proximal part, gradually becoming smaller distally ( Fig. 2AView FIGURE 2). Aboral physa differentiated from scapus, naked, not rounded but tapered, without nemathybomes ( Fig. 2AView FIGURE 2). Tentacles 16 in number, in two cycles of eight, relative size of each cycle unclear because tentacles contracted into scapus.

Internal anatomy. Eight perfect mesenteries, macrocnemes, distributed along whole body from distal to proximal end. These eight are the paired dorsal and ventral directives plus four unpaired lateral mesenteries. Eight tiny microcnemes, without muscles, limited to distal-most part: four between dorsal directives and dorso-lateral mesenteries, two between dorso- and ventro-lateral mesenteries, and two between ventro-lateral mesenteries and ventral directives. All macrocnemic mesenteries bear retractor and parietal muscles. The retractor muscle of each lateral mesentery faces ventrally ( Fig. 2E, FView FIGURE 2). Each retractor muscle distinctly developed; diffuse, with approximately 20 simple or slightly branched muscular processes next to actinopharynx ( Fig. 2DView FIGURE 2); diffuse or restricted to parietal muscle side, developed like a pennon, with 10–25 simple or slightly branched muscular processes in lower part ( Fig. 2E, FView FIGURE 2). Parietal muscles of macrocnemes distinct, semi-elliptic, with 10 slightly branched muscular processes in each side ( Fig. 2View FIGURE 2 D–F). Actinopharynx very short, grooved but without distinct siphonoglyph. One tentacle in each endo- or exo-coel. Tentacular longitudal muscle ectodermal and distinct. Marginal sphincter muscle and basilar muscle absent ( Fig. 2C, HView FIGURE 2). Mesoglea generally thin in mesenteries, and comparatively thick in body wall (Fig, 2D, F). Nemathybomes far thicker than mesoglea, greatly protruding from body wall and containing very large basitrichs ( Fig. 2F, GView FIGURE 2). Gonads on mesenteries between retractor muscle and filament; gametocytes immature.

Cnidome. Spirocysts, basitrichs, microbasic b -mastigophores, microbasic p -mastigophores, and microbasic amastigophores ( Table 1, Fig. 4View FIGURE 4 A–D; NSMT-Co 1654). Two sizes of basitrichs in actinopharynx; three sizes of basitrichs in nemathybomes.

Deriviation of Japanese name. Japanese name “oozutu” means a cannon, because the huge nemathybomes of this species are suggestive of spherical projectiles of cannon, and the cylindrical shape of the body resembles to a cannon barrel. Nemathybome is called as “shihoudan” in Japanese, which is constructed by shihou (= cnidae) + dan (=projectile or bullet), so this Japanese name matches E. aff. tuberculata  . “Mushimodoki-ginchaku” means Edwardsia  .

Remarks. Edwardsia tuberculata  was originally described in Duben and Koren (1847), and more detailed morphological features were described in Carlgren (1921). Morphology of the examined specimens agrees well with the description by Carlgren (1921): shrunken body size is 2 cm in length and 7 mm in width ( Fig. 2AView FIGURE 2); a few outstandingly large nemathybomes look like papillae arranged in 8 rows ( Fig. 2B, F, GView FIGURE 2); physa is developed but flattened or tapered ( Fig. 2A, HView FIGURE 2); retractor muscle is diffused with slightly branched processes and parietal muscle is distinct with 20 processes ( Fig. 2View FIGURE 2 D–F). The cnidom also almost perfectly corresponds to the description of Carlgren (1921): this species is characterized by large nemathybomes that contain huge basitrichs. The larger type of basitrichs in nemathybomes of our specimen are 116–187 µm in length and 4.8–9.0 µm in width ( Table 1; Fig. 4CView FIGURE 4 2View FIGURE 2). This matches the nematocysts of E. tuberculata  reported by Carlgren (1921), which he measured at 110–190 µm in length and 5–7 µm in width. In filaments, Carlgren (1921) mentioned that some of nematocysts are a little broader than the others. This observation would be convincing if one assumes that the wide nematocyst of Carlgren (1921) is what we identify as microbasic b -mastigophores in our specimen. There were some small differences between the description and our specimens. For example, the retractor muscle of our specimen is composed of 10–25 muscular processes while Carlgren (1921) mentioned more 30 processes, and we found some spirocyst in actinopharynx, although Carlgren (1921) did not mention these.

According to England (1987), in addition to E. tuberculata  three other species of Edwardsia  have basitrichs over 150 µm in length; E. californica McMurrich, 1913  , E. maroccana Carlgren, 1931  , and E. claparedi (Panceri. 1869)  . However, they never exceed 170 µm even in maximum size ( Carlgren, 1931, 1936; England, 1987; Manuel, 1977). The huge basitrichs are, however, now also reported in Edwardsia alternobomen  sp. nov., described below, which has basitrichs over 200 µm in length ( Table 1, Fig. 2G2View FIGURE 2).

Edwardsia tuberculata  is distinguished from the other species with large basitrichs in their nemathybomes by having larger basitrichs than those other species and by some anatomical features. Between mesenteries, E. tuberculata  consistently has a single row of nemathybomes, whereas E. californica  has two or three rows on the proximal part ( Carlgren, 1936). Edwardsia tuberculata  has flattened physa but E. californica  has very apparent, large, rounded physa. Edwardsia californica  has a very characteristic restricted retractor muscle with approximately 40 muscular processes, whereas one of our specimens has diffuse retractor muscle composed of about 20 processes. According to Carlgren (1931), Edwardsia maroccana  has more developed muscles with 30 processes, and it is apparently pinnate near the column, whereas those of E. tuberculata  do not branch so much. In addition, Carlgren (1931) showed basitrichs of 30–40 µm in length and 6.5 µm in width bearing a shimmering thread in the capsule in the actinopharynx, these are likely a kind of mastigophore, a type of nematocyst not found in actinopharynx of the examined specimen of E. tuberculata  . The body size of E. tuberculata  (20–25 mm in length) is completely different from Edwardsia claparedi  , which reach to 120 mm in length ( Manuel, 1981).

Edwardsia tuberculata  can also be distinguished from the other species of Edwardsia  that have two types of basitrichs in their nemathybomes (i.e., E. elegans Verrill, 1869  , Edwardsia handi Daly and Ljubenkov, 2008  , E. hantueusis  England, 1987, E. sulcata Verrill, 1864  ). However, the larger type of basitrichs in nemathybomes of those species barely exceed 100 μm and at most 117 µm for E. handi ( Daly and Ljubenkov, 2008)  .

Although our specimens clearly align with the description of E. tuberculata  , this species is distributed only in north western Europe and there is no record from the Pacific or from the eastern Arctic Ocean. Recognizing that expanding the range so much without intermediate populations or an explanation for the long-distance dispersal is problematic, and pending comprehensive analysis through genetics, we mark our specimens as having an affinity for E. tuberculata  , rather than assigning that name to them definitively.

Kingdom

Animalia

Phylum

Cnidaria

Class

Anthozoa

Order

Actiniaria

Family

Edwardsiidae

Genus

Edwardsia

Loc

Edwardsia aff. tuberculata Duben and Koren, 1847

Izumi, Takato & Fujita, Toshihiko 2019
2019
Loc

Edwardsia handi

Daly and Ljubenkov 2008
2008
Loc

E. handi (

Daly and Ljubenkov 2008
2008
Loc

E. hantueusis

England 1987
1987
Loc

Edwardsia maroccana

Carlgren 1931
1931
Loc

E. californica

McMurrich 1913
1913
Loc

E. californica

McMurrich 1913
1913
Loc

Edwardsia californica

McMurrich 1913
1913
Loc

Edwardsia claparedi

Panceri 1869
1869
Loc

E. elegans

Verrill 1869
1869
Loc

E. sulcata

Verrill 1864
1864
Loc

Edwardsia tuberculata

Duben and Koren 1847
1847
Loc

E. tuberculata

Duben and Koren 1847
1847
Loc

Edwardsia tuberculata

Duben and Koren 1847
1847
Loc

E. tuberculata

Duben and Koren 1847
1847
Loc

E. tuberculata

Duben and Koren 1847
1847
Loc

E. tuberculata

Duben and Koren 1847
1847
Loc

Edwardsia tuberculata

Duben and Koren 1847
1847
Loc

E. tuberculata

Duben and Koren 1847
1847
Loc

E. tuberculata

Duben and Koren 1847
1847
Loc

Edwardsia

de Quatrefages 1842
1842