Morbakka virulenta ( Kishinouye, 1910 )

Bentlage, Bastian & Lewis, Cheryl, 2012, An illustrated key and synopsis of the families and genera of carybdeid box jellyfishes (Cnidaria: Cubozoa: Carybdeida), with emphasis on the “ Irukandji family ” (Carukiidae), Journal of Natural History (J. Nat. Hist.) 46 (41 - 42), pp. 2595-2620 : 2612-2616

Morbakka virulenta ( Kishinouye, 1910)

( Figures 4I. J , 7 , 8 )

Tamoya virulenta Kishinouye (1910: 7 , Pl. I, fig. 10); Uchida (1947: 316); Williamson et al. (1996: 414).

Tamoya alata Uchida (1929: 172 , figs 8–88). non Tamoya alata Reynaud [refers to Copula sivickisi ]: Uchida (1929: 178–80; figs 86, 87).

Tamoya bursaria Uchida (1947: 314–16 , figs. 2, 3); Uchida (1954: 209–19).

Tamoya haplonema Uchida (1970: 289 , 293–4, figs 3, 4); Yamasu and Yoshida (1976: 325–6); Yamaguchi (1982: 249); Kubota (1998: 33); Iwama (2001: 109).

Tamoya bursaria (? gargantua ) Williamson et al. (1996: 414).

Tamoya gargantua Williamson et al. (1996: 414) .

Material examined

Neotype. USNM 1124253 , female, 150 mm BH, 60 mm IRW, Hiroshima Bay , Japan.

Other material. USNM 1124251, 150 mm BH, 68 mm IRW, Hiroshima Bay , Japan ; USNM 1124252, 140 mm BH, 50 mm IRW, Hiroshima Bay , Japan .

Type locality

Hiroshima Bay, Honshu, Japan.

Common name

Hikurage (“fire jellyfish” in Japanese).

Diagnosis

Large carybdeid medusa (up to 150 mm BH) lacking gastric phacellae; robust bell densely covered with nematocyst warts ( Figure 7A ). Morbakka virulenta possesses “rabbit-ear”-shaped rhopaliar horns and differs from its congener, M. fenneri , in that M. virulenta ’s rhopaliar horns are swollen rather than pointed at the tips, and project from the top centre of the rhopaliar niche at a more oblique angle ( Figure 4H versus 4I). Further, M. virulenta lacks the nematocyst wart on the rhopaliar stalk that is characteristic of M. fenneri .

Description

Carybdeid medusa, bell taller than wide, rectangular, with flat apex, and leaflike gonads in mature individuals ( Figure 7A, B ); extended tentacles flat, cord-like in live specimens ( Figure 7B ). Exumbrella densely covered with nematocyst warts ( Figure 7A ). Maximum BH about 150 mm (observed range from 140 to 150 mm in mature individuals) and maximum IRW about 68 mm (observed range from 50 to 68 mm in mature individuals). Gastric phacellae absent; stomach with welldeveloped musculature (area corrugata; Figure 7C ). Manubrium with rounded, smooth-edged lips ( Figure 7D ) extending to about one-third of BH from subumbrellar ostium. Mesenteries well developed in upper half of the subumbrella, extending cord-like to rhopaliar window ( Figure 7D ). Frenulum consisting of a single sheet that splits longitudinally near the rhopaliar niche, extending onto the lower half of the rhopaliar window ( Figure 7E ); frenulum covering three-quarters of the distance between velarial turnover and velarial margin ( Figure 7E ). Perradial lappets broad, triangular, not reaching subumbrellar edge of velarium ( Figure 7F ); approximately 7–10 nematocyst warts on each side of the perradial lappet, mostly arranged in single rows but some scattered ( Figures 4J and 7F ). Velarium with six to eight complex dendritic canals per octant with lateral diverticula per octant ( Figures 4J and 7F ). Pedalium keeled on both sides of lateral median line; inner keel with overhang ( Figure 7G ). Outer keel with warts ( Figure 7G ), that appear to have mostly rubbed off after collection. Pedalial canal with thorn-like extension ( Figure 7H ). Rhopaliar niche ostium frown-shaped with “rabbit-ear”-like rhopaliar horns ( Figures 4I and 7I ).

Cnidome

Tentacles were truncated in the preserved specimens, but nematocysts were sampled from both the distal end of the truncated tentacles as well as the proximal base of the tentacles near the pedalia. Distal tentacle tip: rod-shaped, microbasic p-mastigophores (L 58.2- 66.2 -71.2 µm, W 14.1 - 18.2 -16 µm, n = 6; Figure 8A, B ); large, oval, holotrichous isorhizas (L 59.1- 60.1 -64.8 µm, W 31.2 - 38.6 -39.3 µm, n = 20; Figure 8C, D ); oval, microbasic p-euryteles (L 18- 21.8 -23.6 µm, W 13.5 - 15.5 -17.6 µm, n = 5; Figure 8E, F ); small, oval amastigophores (L 10.6 µm, W 6.4 µm, n = 1; Figure 8G ). Proximal tentacle/tentacle base: rod-shaped, microbasic p-mastigophores (L 69.4- 71.7 -74.6 µm, W 14.9 - 16.7 -19.1 µm, n = 20; Figure 8H ); large, oval, holotrichous isorhizas (L 61.8- 66.9 -77.6 µm, W 30.1 - 35.9 -43.3 µm, n = 20; Figure 8I, J ); oval, microbasic p-euryteles (L 43.3- 43.3 -44.5 µm, W 18.6 - 18.6 -21.1 µm, n = 3; Figure 8K ). Manubrium:?oval, microbasic p-euryteles (L 20.7 µm, W 12.8 µm, n = 1; Figure 8L ). Pedalial warts: large, oval, holotrichous isorhizas (L 60.9- 64.5 -69.5 µm, W 37.8 - 40.6 -43.2 µm, n = 20; Figure 8M, N ); rod-shaped, microbasic p-mastigophores (L 61.7- 67.2 -71 µm, W 15.7 - 18.9 -21.3 µm, n = 13; Figure 8O, P ). Exumbrellar warts: large, oval, holotrichous isorhizas (L 42.9- 45.9 -50.2 µm, W 27.6 - 31 -33.6 µm, n = 20; Figure 8Q ); rod-shaped, microbasic p-mastigophores (L 62.8- 70 -79.4 µm, W 14.7 - 17.2 -19.1 µm, n = 20; Figure 8R ). Apex warts: oval, holotrichous isorhizas (L 33.6- 36.8 -40.4 µm, W 22.8 - 25.5 -27.6 µm, n = 20; Figure 8S, T ); rod-shaped, microbasic p-mastigophores (L 67.9 and 68 µm, W 16.8 and 19.9 µm, n = 2; Figure 8U );?large, oval, holotrichous isorhizas (only empty capsules observed, L 48.3 and 53 µm, W 27.6 and 31.6 µm, n = 2).

Remarks

A neotype is designated for M. virulenta to stabilize its taxonomic status and clarify its identity, with particular emphasis on differentiating it from its congener M. fenneri . The description and drawing of M. virulenta in the original description (as Tamoya haplonema ; Kishinouye 1910) agree well with the material examined by us, but lack the characters typical of Morbakka , in particular the rhopaliar horns. We believe Kishinouye (1910) overlooked these characters, as did his contemporaries, because the potential importance of these characters had not been recognized. The original description does not mention the presence of vertical gastric phacellae that are characteristic of Tamoya , which suggests that the specimen(s) investigated by Kishinouye (1910) did not possess gastric phacellae – a trait characteristic of Carukiidae . Additionally, the common name used by Kishinouye (1910) for T. virulenta is “Hikurage”, the same name applied to the specimens we studied. The original type locality was the Inland Sea off Kagoshima and Innoshima; Hiroshima Bay is about 50 km east of Innoshima.

Figures

Figure 4. Characters distinguishing the genera of Carukiidae. The location of the characters illustrated in (A–J) are indicated on the specimen in the upper left hand corner. The rhopaliar niche ostium is always horizontally oriented and more or less oval in the Carukiidae; however, its shape may vary among specimens. Carukia: (A) rhopaliar niche with horns, (B) velarium, (C) tentacle with “neckerchiefs”; Malo: (D) rhopaliar niche with horns, (E) velarium; Gerongia: (F) rhopaliar niche with horns, (G) velarium; Morbakka: (H, I) differences of rhopaliar niche and horns between M. fenneri (H) and M. virulenta (I), in both cases the rhopaliar horns are “rabbit-ear” shaped but the angle and breadth of the horns vary, (J) velarium. nc: “neckerchief”, nw: nematocyst wart, pl: perradial lappet, rn: rhopaliar niche, rno: rhopaliar niche ostium, rho: rhopaliar horn, ve: velarium, vec: velarial canal.

Figure 7. Morbakka virulenta: (A) specimen in its natural environment in Hiroshima Bay (image courtesy of Masato Kawahara), (B) whole specimen of the neotype USNM 1124253, (C) interior of stomach with area corrugata, (D) subumbrellar view with manubrium and mesentery, (E) frenulum, (F) velarium with perradial lappet, (G) pedalium with nematocyst warts on outer keel and overhang on inner keel, (H) pedalial canal with pedalial canal bend, (I) rhopaliar niche. (B, C, I) USNM 1124253; (H) USNM 114252. ac: area corrugata, fre: frenulum, ik: inner keel, ma: manubrium, me: mesentery, ok: outer keel, pl: perradial lappet, rho: rhopaliar horn, rno: rhopaliar niche ostium, ve: velarium. Scale bars: 10 mm.

Figure 8. Nematocysts of Morbakka virulenta; for identifications and sizes see cnidome description.