Carybdea rastonii Haacke, 1886

Acevedo, Melissa J., Straehler-Pohl, Ilka, Morandini, André C., Stampar, Sergio N., Bentlage, Bastian, Matsumoto, George I., Yanagihara, Angel, Toshino, Sho, Bordehore, César & Fuentes, Verónica L., 2019, Revision of the genus Carybdea (Cnidaria: Cubozoa: Carybdeidae): clarifying the identity of its type species Carybdea marsupialis, Zootaxa 4543 (4), pp. 515-548 : 529-534

Carybdea rastonii Haacke, 1886

Figs. 3 F–I

Material examined: One (1) unregistered, preserved specimen, from Mirimbula (Victoria, Australia), collected by G. Hood, March 0 3, 2000; One (1) unregistered, preserved specimen, from Waterloo Bay (South Australia), collected by J. Seymour, February 1999 .

Diagnosis: Gastric phacellae horizontal linear, gastric filaments with multiple roots, short stemmed; velarial canals 2 per octant, triforked; pedalial knee bend rounded, no appendage.

Description: Adult medusa: Bell ( Fig. 3F ), highly transparent, colourless, slightly higher than wide, cuboid to almost cubical in shape, regularly scattered with colourless, nematocyst warts, from apex to bell margin, more dense on the bell sides than on the bell edges; nematocysts roundish to oval with different diameters, largest approx. 0.5 mm in diameter, velarium without nematocyst warts; apex plane to round convex, mesoglea thick, slight horizontal constriction near the top present. Bell height 30–35 mm high, bell width 20–30 mm (interrhopalial diameter).

Pedalia ( Fig. 3H ), 4, simple, unbranched flattened, scalpel-shaped, approx. 1/3–1/2 bell height in length, situated in each interradial corner; outer wing scattered with large, white to light brown nematocyst warts or bands of nematocysts (approx. 0.5 mm in length) covering the outer keel of the pedalia; inner wing free of nematocyst warts; pedalia carrying single, white to flesh coloured tentacles in preserved specimens, in living specimens pale pink to brownish when contracted, resembling bead-chain when relaxed with white nematocyst-battery rings on a pale pink tentacle “string”. Pedalial canal slightly tapering at upper end, rounded knee bend without any hook or thorn appended, going straight through the pedalium, diamond-shaped in cross-section with sharp outer keels at proximal end up to velarium level then turning circular in cross-section towards distal end.

Rhopalia, 4, located inside heart-shaped rhopalial niche ostium, with triangular covering scale; few small, round nematocyst warts on scale; approx. 1/6 to 1/5 of bell height up from margin; rhopalium with 6 eyes (2 median lens eyes + 2 lateral slit eyes + 2 lateral pit eyes).

Velarium ( Fig. 3I ), free of nematocyst warts, containing 2 velarial canal roots per octant, canals broad in width, main canal tri-forked, square tipped, side branches sometimes bi-forked; canals flanking frenulum slightly smaller than canals flanking pedalia, all canals equally complex.

Manubrium (1/2 to 3/4 of bell height in length), 4 lobes, cruciform with long, straight and blunt mouth arms,, without nematocyst warts, connected to large stomach; stomach communicates perradially with 4 gastric pockets leading into velarial canals.

Gastric phacellae ( Fig. 3G ), pale pink to brownish coloured, 4, horizontal rows, in 4 stomach corners, consisting of ca. 12–15 single, short-stemmed, brush shaped filaments per quadrant.

Gonads, 4 pairs narrow leaf-like- to blunt spear-head-shaped, separated by interradial septum, extending from stomach rim to bell margin, tapering towards stomach rim, tapering at rhopalia level, and broadening again towards bell margin; sexes separated but unimorph; ripe gonads yellowish to flesh coloured in preserved specimens.

Remarks: Haacke (1886) gave a detailed description of a species that he had sampled in St. Vincents Gulf in Southern Australia and which he named C. rastonii . Later, the species C. arborifera, Maas 1897 and C. brevipedalia, Kishinouye 1891 were reclassified as “geographic races” ( Bigelow 1909) or local varieties (“lokale Varietäten”) ( Maas 1897, 1910) of the same species and synonyms of C. rastonii ( Maas 1903, 1910; Mayer 1906, 1910; Bigelow 1938; Kramp 1961). This gave C. rastonii a wide distribution throughout the Pacific Ocean on both the eastern and western margins [ Japan, Philippines, Taiwan, Guam ( USA), California ( USA), Hawaii ( USA)] (e.g. Yatsu 1917, Matsumoto 1995, Kingsford & Mooney 2014). But Gershwin (2006) demonstrated that the Japanese population has a distinctive cnidome compared to C. rastonii from Australia. Moreover, Bentlage et al. (2010) showed that the populations from Hawaii and Japan were a case of several species being united under the name C. rastonii and resurrected the species C. arborifera (Hawaii) and C. brevipedalia ( Japan) .

Reported distribution of C. rastonii : Australia

Figures

FIGURE 3. Characters for identification in species of the family Carybdeidae (species in order of appearance in the text; preserved specimens). C. brevipedalia: A) adult medusa (preserved) B) linear gastric phacellus C) gastric filament, note long stem (arrow) D) peaked (arrow) pedalial canal knee bend E) octant of velarium with 3 canal roots. C. rastonii: F) adult medusa (preserved) G) linear gastric phacellus H) pedalial canal with rounded knee bend I) octant of velarium, note two broad, blunt tipped velarial canals. Scale bar: 1 cm.