Meteorona kishinouyei, Toshino, Sho, Miyake, Hiroshi & Shibata, Haruka, 2015

Toshino, Sho, Miyake, Hiroshi & Shibata, Haruka, 2015, Meteoronakishinouyei, a new family, genus and species (Cnidaria, Cubozoa, Chirodropida) from Japanese Waters, ZooKeys 503, pp. 1-21 : 5-15

Taxon classification Animalia Chirodropida Chiropsellidae

Meteorona kishinouyei sp. n. Figures 3, 4, 5, 6, 7, 8, 9, 10, 11, 12

Material examined.

Holotype: NSMT-Co1572. Eastern Japan, Fukushima Prefecture, Souma, Matsukawa-ura, 37°48'39.3"N, 140°58'3.3"E, 14 October 2013, collector: Ko Tomikawa, one adult male. Paratypes. NSMT-Co1568, 1569, 1570. Eastern Japan, Kanagawa Prefecture, Fujisawa, Enoshima, Shonan Port, 35°18'4.75"N, 139°28'61.0"E, 23 August 2011, collector: Haruka Shibata, one adult female. NSMT-Co1571. Eastern Japan, Fukushima Prefecture, Iwaki, Onahama Port, 36°56'29.1"N, 140°54'.32.9"E, 18 October 2013, collector: Shun Ishikawa, one adult female.

Description.

Adult medusae with smooth exumbrella, with evenly thick mesoglea of rigid consistency (Fig. 3, Fig. 4, Fig. 5). BH about 35 mm and DBW about 50 mm (Table 3). Interradius thickened throughout bell height, with deep median furrow spanning height of bell. Adradial furrows spanning lower two thirds of bell. Coronal indentation shallow just below apex. Exumbrella lacking nematocyst warts or freckles. Gonads attached along entire length of interradial septa, leaf-shaped, not overlapping along the interradius (Fig. 6A, 7A). Manubrium length about 40% of bell height. Manubrium cruciform with four narrow, lanceolate lips (Fig. 6B).

Gastric saccules unbranched, slightly raised and opaque (Fig. 5D, 6C, 7B). Gastric phacellae horseshoe-shaped in each corner of stomach (Fig. 6D, 7C). Gastric cirri simple and unbranched (Fig. 6E, 7D). Sensory niches four, perradial, U-shaped, with one shallow covering scale above and no lower scale, upper scale with central tongue-shaped flap partially shielding rhopalium, located approximately 1/6 of bell height from velarial turnover (Fig. 6F, G, 7E, F). The rhopaliar niche located in a triangular shaped depression of exumbrella (Fig. 6F, 7E). Subumbrellar rhopalial windows flat (Fig. 6H). Each of the four rhopalia bearing a set of six eyes, with the two median possessing prominent lenses and the four lateral ones adjacent to the lens eyes being pigment pits and slit (Fig. 6 I–K, Fig. 7G, H). A single broad bean shaped statolith located behind each complex eye (Fig. 6 I–K). Velarial canals one per octant, dendritic, with only the tips defined along the velarial margin (Fig. 6L, Fig. 7I). Frenulum a single solid, gelatinous struc ture, extending to near velarial margin (Fig. 6L). Velarial width about 20% of DSW. Pedalia scalpel-like, each bearing one tentacle (Fig. 6M, Fig. 7J). Pedalia about half of bell height, inner keel rounded, about two times the width of pedalial canal. Outer keel width approximately twice that of pedalial canal, inner keel width and outer keel width almost equal. Proximal pedalial canal bend slight volcano-shaped (Fig. 6N, Fig. 7K). Tentacles four, with one per pedalium, base width up to 2.7 mm thick, round in cross section, with nematocyst rings alternate thick and thin in preserved specimens (Fig. 6O, 7L). Color and length of tentacles in living specimens was light brownish (Fig. 3A, B).

The smallest young medusa (NSMT-Co 1570) had a BH of about 15 mm, DBW of about 20 mm (Fig. 8, 9). Mesoglea was thin and softer than that of adults. Adradial furrows spanning half of the bell height (Fig. 8A, 9A). Interradial furrows spanning the entire height of the bell (Fig. 8B, 9B). Coronal indentation shallow and exumbrella nematocyst freckles absent. Gonads attached along entire length of interradial septa, leaf-shaped, not overlapping along the interradius (Fig. 10A). Manubrium length about 20% of bell height. Gastric saccules not developed. Gastric phacellae four-leaf clover shaped in each corner of stomach (Figs 8C, 9C, 10B). Depression of exumbrella not developed. Upper medial rhopaliar scale flap shorter than in adults (Fig. 10C, D). Velarial canals one per octant, dendritic but with minor branching (Fig. 10E). Pedalium scalpel-like (Fig. 10F). Volcano-shaped pedalial canal bend smoother than in adults (Fig. 10G). Tentacle with nematocyst rings alternate thick and thin in preserved specimens (Fig. 10H).

Cnidome. Six different nematocyst types identified and measured in the paratype specimen (NSMT-Co1571) (Table 4, Fig. 11). Tentacle: Large microbasic p-rhopaloids, banana-shaped p-mastigophores, small oval beehive isorhizas, rod-shaped isorhizas, small sub-spherical p-rhopaloids. Manubrium: Tiny microbasic euryteles, small sub-spherical p-rhopaloids. Phacellae: Tiny microbasic euryteles, small sub-spherical p-rhopaloids. Exumbrella lacking nematocysts.

Molecular phylogenetics.

In the resulting ML tree (Fig. 12), three major monophyletic clades were formed in the order Chirodropida : 1) Chirodropidae ( Chironex fleckeri and Chironex yamaguchii ); 2) Chiropsalmidae ( Chiropsalmus quadrumanus ); 3) A third group ( Meteorona kishinouyei and Chiropsella bronzie ). The monophyly of the third group was evident in the 18S phylogenetic tree with high bootstrap values, well supporting the validity of the new family.

Habitat and ecology.

Holotype specimen of Meteorona kishinouyei was collected near shore in shallow waters of the Matsukawa-ura lagoon, Fukushima prefecture, eastern Japan. Until March 2011, the north part of the lagoon extended to the sea via a man-made channel. However, the channel was destroyed and considerable sea water flowed into the lagoon as a result of the 2011 Tohoku earthquake and tsunami. Meteorona kishinouyei medusae may have been brought into the lagoon on the high waves. Moreover, Meteorona kishinouyei may be a neritic species. Young medusae appeared during August, while adult medusae appeared between August and November. Carybdea brevipedalia was collected together with Meteorona kishinouyei along at Onahama port and Shonan at the water surface in a shallow area (water depth 3-10 m) port during daytime. Polyps of Meteorona kishinouyei may metamorphose into young medusae during summer. However, the polyp stage and life history are unknown.

Etymology.

The species is named kishinouyei (noun in apposition) to honor Professor Kamakichi Kishinouye, zoologist and fishery scientist. Kishinouye’s meticulous studies and observations have led to many important contributions in the description of cubozoan zoology

Differential diagnosis.

A comparison of key features of the species of Chirodropida is presented in Table 5. Meteorona kishinouyei can be distinguished from all other chirodropid species by shape of pedalium, gastric saccules and rhopaliar niche. All of the species in the order Chirodropida have branching pedalia, each bearing multiple tentacles. Meteorona kishinouyei has one tentacle per unbranching pedalium like species of the order Carybdeida . Shape of gastric saccules are cock’s-comb shaped/grape-cluster-like ( Chironex ), elongate, tapered, with numerous axial processes, or absent ( Chirodropus ) in Chirodropidae , finger-like in Chiropsalmidae , spherical in Chiropsella . Meteorona kishinouyei were slightly raised. All chirodropids have sensory niches located in a triangular shaped depression of the exumbrella. However, only Meteorona kishonouyei and Chiropsella have a central flap hanging down from the upper scale of the rhopaliar niche. Exumbrella nematocysts are lacking in all chirodropid species expect Chiropsalmus .