Morbakka sp.

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 : 2616-2617

Morbakka sp.

( Figure 9 )

Carybdea alata, var. grandis Mayer (1915: 171 later became USNM 28713; only specimen from Manila Bay, Luzon); Mayer (1917: 189 as USNM 28713); Light (1921: 29–30).

non Carybdea alata, var. grandis [refers to Alatina grandis ] Mayer (1915: 171; specimen from Mount Putri, Borneo); Mayer (1917: 171; specimen from Mount Putri, Borneo).

Material examined

USNM 28713 , two individuals, ∼ 100 mm and ∼ 50 mm IRW, and ∼ 80 mm BH and ∼ 40 mm IRW; Manila Bay , The Philippines .

Description

Lot USNM 28713 contains two large carybdeid specimens ( Figure 9A, B ) collected by the steamer Albatross in 1909 during the Pacific Expedition of the US Fish Commission. The specimens were originally identified as Carybdea grandis (now Alatina grandis ) by A.G. Mayer. However, we determined that both specimens belong to Carukiidae . In particular, both specimens appear to be species of Morbakka . The material is in poor condition and it is unclear if the specimens belong to one of the two described species of Morbakka ( M. fenneri or M. virulenta ), or if they represent an undescribed species. Both specimens display morphological characters that demonstrate their affinity to the genus Morbakka . In particular, both lack gastric phacellae, but possess “rabbit-ear”-like rhopaliar horns ( Figure 9C ), thorn-shaped extensions at the bases of their pedalial canals ( Figure 9D, E ), and numerous branching velarial canals with lateral diverticula ( Figure 9F, G ). Nematocyst warts on the perradial lappets, the exumbrella, or the pedalia were not observed, but this is likely a result of the poor preservation of the specimens.

Cnidome

Nematocysts were sampled from the tentacles, but all capsules sampled were discharged and lacked any interpretable features on the discharged shaft ( Figure 9H, I ). The following measurements were obtained from the unidentified nematocysts: L 51.6- 55.8 -59.3 µm, W 27.5 - 29.8 -31.2 µm (n = 9).

Figures

Figure 9. Morbakka sp. from the Philippines (USNM 28713): (A) whole specimen of the large individual, (B) whole specimen of the small individual, (C) rhopaliar niche ostium, (D) pedalial canal of the large specimen, (E) pedalial canal bend of the small specimen, (F) velarial canals of the small specimen, (G) velarial canals of the large specimen, (H, I) unidentified nematocyst capsules from the tentacles. rho: rhopaliar horn, rno: rhopaliar niche ostium, pcb: pedalial canal bend, pl: perradial lappet. Scale bars: 10 mm (A, B and G), 5 mm (C–F), and 50 µm (H, I).