Revision of the genus Carybdea (Cnidaria: Cubozoa: Carybdeidae): clarifying the identity of its type species Carybdea marsupialis

Abstract

While records of Carybdea marsupialis in the literature suggest a worldwide distribution of this species, the validity of some of these records has been questioned recently, as has the validity of some nominal Carybdea species. We inspected material of all known species of Carybdea from multiple locations (i.e. Spain, Algeria, Tunisia, Puerto Rico, California, Hawaii, Australia, South Africa, and Japan) using morphological and genetic tools to differentiate Carybdea species as well as understand their evolutionary relationships. We observed morphological differences between adult medusae of Mediterranean and Caribbean C. marsupialis; the most obvious differences were the structure of the phacellae, the structure of the pedalial canal knee bend, and the number and structure of the velarial canals. The characters of the adult Mediterranean specimens agree with the description provided by Claus (1878) for individuals of C. marsupialis from the Adriatic Sea (Italy); specimens from the Caribbean (Puerto Rico) agreed with the description of C. xaymacana by Conant (1897). Significant differences between both species were also observed in the newly released medusa stage. Further, we resolved a discord about the undefined polyp culture originating from Puerto Rico that was long considered Carybdea marsupialis but should be referred to as C. xaymacana. Although C. marsupialis is currently considered the only species of Cubozoa to occur in the Mediterranean, specimens collected in Algeria and Tunisia suggest that species of Alatinidae may also be present in the Mediterranean. Our investigations indicate that Carybdea spp. are more restricted in their geographical distribution than has been recognized historically. These findings confirm that Carybdea arborifera Maas, 1897 from Hawaii, Carybdea branchi, Gershwin & Gibbons, 2009 from South Africa, Carybdea brevipedalia Kishinouye, 1891 from Japan, Carybdea confusa Straehler-Pohl, Matsumoto & Acevedo, 2017 from California, Carybdea marsupialis Linnaeus, 1758 from the European Mediterranean Sea, Carybdea rastonii Haacke, 1886 from South Australia, and Carybdea xaymacana, Conant, 1897 from the Caribbean Sea are valid names representing distinct species, rather than synonyms. A taxonomic key for all valid species is provided, and a neotype for C. marsupialis is designated.

A new species detected in the collection of the Natural History Museum of Denmark of the Dana Expedition from 1928–30: <i>Carybdea irregularis</i> sp. nov. (Cnidaria, Scyphozoa, Cubomedusae, Carybdeida, Carybdeidae) from French Polynesian waters

“…Due to the morphological analyses of this study I conclude that the Polynesian carybdeid populations from Nuku Hiwa and Mangareva belong to none of the eight currently accepted species (Acevedo et al 2019) Bigelow (1909) of a carybdeid medusa sampled during the Albatross Expedition 1904-05 in Mangareva, the Gambier Islands (French Polynesia) with preserved carybdeid medusae (C, F, H, K, M) sampled during the Dana Expedition 1928-30 in Nuka Hiwa, the Marquesas (French Polynesia): A: Sketch of habitus (bell height 14 mm); B: Photo of habitus (bell height 14 mm), C: Habitus of preserved specimen (bell height 15 mm); D: Sketch of diaginal section of bell at apex level; E: Sketch of longitudinal section of bell at apex level, note very short manubrium; F: Lateral view of apex of preserved specimen, note very short manubrium; G: Sketch of gastric phacellum, note thick, branched stems of filaments; H: Gastric phacellum of preserved specimen, note thick, branched stems (contracted state) of filaments; I: Sketch of longitudinal section of bell at rhopalial niche level, note single triangular covering scale hanging over rhopalium; J: Sketch of rhopalium, note 6 eyes (2 median, 2 lateral pit eyes and 2 lateral slit eyes); K: Lateral view of rhopalial niche with rhopalium; L: Sketch of diagonal section of bell at velarium level, note 4 simple velarial canals per quadrant; M: quadrant of velarium, dotted lines mark 4 quite simple velarial canals: cv/vc: velarial canal; f/fr: frenulum; gp: gastric phacellum; M: manubrium; o1: single ocelli (median eyes); o2: paired ocelli (lateral eyes); oc: otocyst (statocyst); t: stump of tentacle Jan 1925: Undetermined: BH 14 mm, IPD 13 mm, PL 9 mm, PW 4 mm; males: BH: 9-14 mm, IPD 9-13 mm, PL 6-9 mm, PW 3-4 mm; juveniles: 9-14 mm, IPD 9-13 mm, PL 6-9 mm, PW 3-4 mm. USA: Museum of Comparative Zoology (MCZ), Harvard University, Cambridge: French Polynesia, Gambier Islands, Mangareva, Rikitea Harbor (23°07′03.0″S 134°58′08.6″W), surface, 3 specimens, collected by Agassiz (U.S. Albatross), 27 Jan-05 Feb 1905 (Agassiz 1906, Bigelow 1909 Examined material: Holotype; Allotype; 8 Paratypes; 5 medusae from Niku Hiva, Marquesas, French Polynesia (Natural History Museum of Denmark, Copenhagen).…”

“…Standard measurements were used (Straehler-Pohl 2014, Acevedo et al 2019): bell height (BH) as length between bell turn-over (velarium excluded from measurement) and top of apex; interpedalial diameter (IPD) as distance between opposite pedalia (outer pedalial wing edges) at the level of the bell turn-over; pedalia length (PL) from attachment to bell (pedalial base) to the tentacle insertion; pedalial width (PW) at the widest diagonal level.…”

“…The French Polynesian specimens possess just two ve-larial canal roots per octant (Figs. 1M, 2N, 3L-O), therefore, it was easy to exclude those species with more than two velarial canal roots per octant from the list of comparable species: the Mediterranean Carybdea marsupialis Caribbean Carybdea xaymacana Conant, 1897 which all show slightly peaked to volcano-shaped knee bends (Gershwin & Gibbons 2009, Acevedo et al 2019Figs. 2D, J, V).…”

“…Next to that, the velarial pattern in C. branchi is far too complex and its size is too large at up to 85 mm bell height (Gershwin & Gibbons 2009, Acevedo et al 2019 compared to the 20 mm bell height in the mature French Polynesian medusae. Additionally, C. confusa and C. xaymacana possess both just one stem per gastric phacellum (Bigelow 1938, Acevedo et al 2019Figs. 2L, X) while the French Polynesian population shows multiple stems per phacellum (Figs.…”

Ernst Haeckel’s mysterious species, Part I: the validity of <i>Carybdea murrayana </i>Haeckel, 1880<i> </i>(Cubomedusae) and revisional notes on Haeckel’s other Carybdeidae

“…A: habitus, sampled by AC Morandini; B: gastric phacellus, note bush-like shape. C: gastric filaments (photo by AC Morandini), note tree-like shape with fused stalks originating from one root, branching several times towards the distal end; D: heart-shaped rhopalial niche, note long and broad niche channel running from niche towards bell rim; E: pedalium, note inner pedalial wing overhanging tentacle insertion (arrow; photo by AC Morandini); F: pedalial canal knee bend with volcano-shaped appendage (white arrow); G: velarium, octant, note 2 canal roots with up to 5 velarial canals of diverse shapes, lobations and branching, canal tips rounded; Carybdea murrayana: H: habitus of paralectotype; I: gastric phacellus, note bush-like shape, note single rooted attachment, and multiple branching of filaments; J: heart-shaped rhopalial niche, note broad niche channel running from niche towards bell rim; K: pedalium, note inner pedalial wing overhanging tentacle insertion (arrow); L: pedalial canal knee bend (dotted line) with volcano-shaped appendage (arrow); M: velarium, octant, note 2 canal roots with up to 5 velarial canals of diverse shapes, lobations and branching, canal tips rounded; Carybdea marsupialis: N: habitus, sampled by MJ Acevedo; O: gastric phacellus, note epaulette-shape; P: heart-shaped rhopalial niche (after Acevedo et al 2019), note short, narrow niche channel; Q: pedalium, note that inner wing does not overhang tentacle insertion, note also rounded pedalial canal knee bend without appendage (arrow); R: velarium, octant, note 3 canal roots with 1 branching canal per root (after Acevedo et al 2019); S: adult specimen, in-live, note brownish bases of gastric phacellae and nematocyst warts (photo by Eduardo Obis). f: frenulum; p: pedalium.…”