Carybdea arborifera

Description: Adult medusa: Bell (Fig. 2 A), blunt pyramidal, highly transparent, mesoglea thin, regularly scattered with small, colourless, nematocyst warts, from apex to bell margin. Bell height, up to 30 mm, bell width, up to 33 mm. Pedalia (Fig. 2 B), 4, simple, unbranched flattened, scalpel-shaped, outer keel lined with rows of white nematocyst warts, carrying single, pale pink coloured homogeneous banded tentacle; pedalial canal diamondshaped in diameter, rounded knee bend without appendage. Rhopalia, 4, located inside heart-shaped rhopalial niche ostium; few, very small, round nematocyst warts on upper scale; rhopalium with 6 eyes (2 median lens eyes + 2 lateral slit eyes + 2 lateral pit eyes). Velarium (Fig. 2 E), free of nematocyst warts, containing 2 velarial canal roots per octant, velarial canals, broad, biforked to multiple branched, rounded tips; canals flanking frenulum, small, mostly bi-forked, canals flanking pedalia, larger, more complexly branched: bi-forked with additional bi-forked side branches. Gastric phacellae (Fig. 2 C), 4, epaulette-shaped, on 4 stomach corners, single rooted, gastric filaments (Fig. 2 D), brush-shaped, multiple short stems attached to single root. In two specimens mysid shrimp and a polychaete worm were found in the stomach. Gonads, 4 pairs, leaf-shaped, extending from stomach to velarium.

Figs. 2 A – E

Diagnosis: Gastric phacellae epaulette shaped, single rooted, multiple stemmed; velarial canals 2 per octant; biforked to multiple branched; Pedalial knee bend rounded; no appendage.

Remarks: Maas (1903, 1910), Bigelow (1909), and Mayer (1910) considered C. arborifera to be a junior synonym of C. rastonii. However, the molecular phylogeny by Bentlage et al. (2010) demonstrated that C. arborifera and C. rastonii are two different species. Reported distribution C. arborifera: Pacific Ocean (Hawaii)

Material examined: Ten (10) different sized specimens from Kewalo Basin (Hawaii), May 29, 2013, collected by Angel Yanagihara; preserved in 5 % buffered formaldehyde solution. Five (5) specimens deposited in the Natural History Museum of Barcelona (Museu de Ciències Naturals de Barcelona), Spain (MZB 2015 - 1703).