Malagazzia michelin Izumi 2026, sp. nov.

Malagazzia michelin Izumi et al. sp. nov. Figs 2, 3, 4, 5 New Japanese name: ama-no-gawa-kurage Material examined. Holotype: Japan – whole medusa specimen preserved in 5 % (v/v) formalin seawater solution, male, umbrella diameter 17 mm; Yamaguchi Prefecture, Yashiro-Jima Island, Katasoe-ga-hama (Fig. 1 B); 30 Sep. 2015; collected by Yoshimi Hamatsu and Hiroaki Uchida, preserved by Sho Toshino; collected on sea surface; NMST-Co 1931. Paratype 1: Japan – whole medusa specimen preserved in 5 % (v / v) formalin seawater solution, male, umbrella diameter 9 mm; Yamaguchi Prefecture, Yashiro-Jima Island, Katasoe-ga-hama (Fig. 1 B); 30 Sep. 2015; collected by Yoshimi Hamatsu and Hiroaki Uchida, preserved by Sho Toshino; collected on sea surface; NMST-Co 1932. Paratype 2: Japan – whole medusa specimen preserved in 5 % (v / v) formalin seawater solution, male, umbrella diameter 10 mm; Nagasaki Prefecture, Sasebo City, Tawara-ga-Ura (Fig. 1 A); 17 Aug. 2008; Hisashi Akiyama; collected on sea surface; CMNH-ZG 1933. Paratype 3: Japan – whole medusa specimen preserved in 5 % (v / v) formalin seawater solution, female, umbrella diameter 10 mm; cultured at the Kuju-kushima Aquarium from the polyps; 25 Jan. 2012; Hisashi Akiyama; collected from the tank; CMNH-ZG 1934. Paratype 4: Japan – whole medusa specimen preserved in 5 % (v / v) formalin seawater solution, juvenile, umbrella diameter 10 mm; cultured at the Kuju-kushima Aquarium from the polyps; 25 Jan. 2012; Hisashi Akiyama; collected from the tank; NMST-Co 1935. Others. Voucher 1: Japan – series of seven whole medusae specimens preserved in 5 % formalin solution, juvenile, umbrella diameter 1–6 mm; cultured at the Kamo Aquarium, reproduced from the polyps; preserved on alternate days starting from polyp generation from 23 Sep. to 3 Oct. 2023; Shuhei Ikeda; collected from the tank; NMST-Co 1936. Voucher 2. Japan – Part of the polyp colony specimen preserved in 5 % formalin solution; cultured at the Kamo Aquarium; 2 Oct. 2023; Shuhei Ikeda; collected from the tank; NMST-Co 1937. Other materials (only pictures remain; used for reproduction and observation of lifecycles). Kuju-kushima- 1: Japan – whole medusa, male, umbrella diameter ca 20 mm; Nagasaki Prefecture, Hirado City, Tabira (Fig. 1 A); 25 Jul. 2017; Yuichi Nozoe; collected on sea surface. Kuju-kushima- 2: Japan – whole medusa, female, umbrella diameter ca 20 mm; Nagasaki Prefecture, Hirado City, Tabira (Fig. 1 A); 25 Jul. 2017; Yuichi Nozoe; collected on sea surface; Kuju-kushima- 3: Japan – whole medusa, male, no data of umbrella diameter; Nagasaki Prefecture, Hirado City, Tabira (Fig. 1 A); 25 Aug. 2012; Shiori Horinouchi; collected on sea surface. Diagnosis. Malagazzia michelin sp. nov. is defined by the following characteristic features: hemispherical umbrella; manubrium with four long lips; without gastric peduncle; gonads on the middle part of radial canals (connected neither to lip or manubrium); four primary radial canals; tentacular bulbs more numerous (12–20); radial canals not branched; radial canals completely surrounded by gonads; brown spots on manubrium and gonads; number of tentacles between radial canals uneven; brown endodermal cores in tentacle bulbs; rudimentary bulbs and statocysts between tentacular bulbs; excretory papillae on each tentacular and rudimentary bulb. Description. Medusae. Umbrella diameter and height approximately 12–20 mm and 6–10 mm, respectively (holotype: 16 mm / 7 mm). Umbrella flat to hemispherical (Fig. 2 A, B). Umbrella with mesoglea, noticeably thickened on apex (Fig. 2 A). Exumbrella transparent (Fig. 2 A, B, D, F), without nematocysts. Manubrium at the centre of umbrella, tubular, cruciform, colour translucent white and pale brown in centre (Fig. 3 A). Gastric peduncle absent. Manubrium length approximately 1.0– 2.5 mm, 1 / 8–1 / 10 of the length of the umbrella diameter, sometimes a little extended beyond umbrella margin. Mouth cruciform, with four long, frilled lips (Fig. 3 B, C). Radial canals four, extending from the base of manubrium to edge of the umbrella (Figs 2, 3 A – C), corresponding with the cruciform orientation of manubrium and mouth, and connected to tentacle bulbs on the marginal end (Fig. 2 E). Radial canals narrow, straight to S-like winding, depend on shape of surrounding gonads. Gonads four, at centre of radial canals, approximately 3 / 4–4 / 5 length of radial canals, neither connected to manubrium nor tentacular bulbs (Fig. 2). Shape of gonad linear to S-like in shape, translucent or whitish in colour; translucent in immature phase (Fig. 3 E) or matured ovary (Fig. 3 F) and whitish in matured testis (Fig. 3 G). Along base of four corners of the cruciform manubria to radial canals surrounded by gonads, presence of egg-like structures filled with dark brownish pigment: four on each side, one or two on manubrium (Fig. 3 A), and one to five (generally two or three) on gonads (Figs 2, 3). Tentacles variable in number, between 12 and 20, simple, cord-like, approximately 3–4 times longer than umbrella height when elongated, covered with nematocysts, slightly translucent whitish (Fig. 3 D), tightly coiled during constriction. Tentacle bulbs same number as tentacles, egg-shaped or triangular, on umbrella margin, having brown endodermal cores inside (Fig. 4), not located at equal intervals (Fig. 2), four tentacular bulbs corresponding with radial canals (Fig. 2). Rudimentary bulbs approximately 50–70, uneven in number, 2–4 between tentacles, no correspondence with radial canals (Fig. 4). Statocyst present, one or two between rudimentary bulbs, and 3–8 between tentacular bulbs. One to four (usually two) statoliths in each statocyst (Fig. 4). One excretory papilla on adaxial side on each tentacular and rudimentary bulb. Velum present, narrow, approximately 1 / 6–1 / 8 of umbrella diameter (Fig. 2 B, F). Polyps (Fig. 5 B – E): colonies stolonal; arising from creeping hydrorhiza. Stolons long, slender, smooth, giving rise to short pedicels. Hydrothecal pedicels usually smooth, slender, approximately 0.7–1.1 mm in length and 0.1–0.15 mm in width, with a conical operculum formed by numerous convergent segments; tentacles arising from hydranth, approximately 16, slender; gonotheca ovate, approximately 0.4 mm in length and 0.2 mm in width, with flat to rounded distal end, gradually tapering towards proximal end, arising from base of hydrothecal pedicels. Development of juvenile medusae (NSMT - Co 1936; Fig. 5 A). Day 1: umbrella diameter and height of just-released medusa approximately 1 mm. Mesoglea approximately 1 / 8 as thick as umbrella height. No gastric peduncle and gonads. Manubrium small, cylindrical, length 1 / 3–1 / 2 of umbrella height. Mouth without lips. Radial canals four, already connecting both to manubrium and margin of umbrella. Tentacle bulbs four; two noticeably smaller than the other two, and alternately larger and smaller. Tentacles present only on larger bulbs. One undeveloped rudimentary bulbs and two statocysts between each tentacular bulb. Day 3: manubrium becoming cruciform. Number of rudimentary bulbs increasing by two between each tentacular bulb. Day 5: two tentacles growing from two small tentacular bulbs. Small lips growing on mouth. Day 7: four tentacular bulbs becoming almost same in size. Primary gonads appearing on radial canals. Day 9: additional tentacular bulbs appearing between the first four bulbs. Lips noticeably separating into four. Day 11: immature gonads surrounding every radial canal. Manubrium and mouth with four lips becoming almost same in shape as that of adult. Eleven tentacular bulbs and 16 rudimentary bulbs finally developing. During rearing of the species at the Kamo and Kuju-kushima aquaria, the maximum size of M. michelin sp. nov. was approximately 10 mm in diameter, never developing to the size of medusae obtained from the wild sea. It took approximately 1–2 months at 20 ° C to reach this maximum size. Etymology. Michelin is derived from the “ Michelin Guide, ” the famous restaurant guidebook. Brown spots are present on the manubrium base or gonads of this species. Especially in the gonads, the number of spots is not fixed and increases with development. These spots can be associated with the “ stars ” of the Michelin guide, bestowed depending on the quality of the restaurant; therefore, we named the species after the shortened name of the guidebook. Derivation of Japanese name: the gonads of these medusae, patches within white winding strips, are associated with the Milky Way with several stars in the night sky. Phylogenetics (Fig. 6). Results of the phylogenetic analysis of Malagazziidae and Aequoreidae show that Malagazzia michelin sp. nov. was most closely related to M. condensum and M. carolinae (node B; bootstrap value [BV] / posterior probability [PP] = 96 / 1); thus, Malagazzia species were recovered as monophyletic. Malagazzia michelin from two localities were nested with high reliability (node A; BV / PP = 100 / 1). At the family level, Malagazziidae (OTU indicated by *) was found to be paraphyletic. Although the species belonging to Malagazziidae and Aequoreidae were monophyletic (node C; BV / PP = 47 / 0.88, a slightly low value), Octophialucium, a member of Malagazziidae, was positioned in several parts of the tree and support values of the phylogenetic tree was too low in several nodes (lower than 50 in bootstrap values and often polytomous in the Bayesian tree).