A new pygmy species of box jellyfish (Cubozoa: Chirodropida) from sub-tropical Australia

Tropical box jellyfish include some of the worlds most venomous animals, leading researchers and the media to wonder whether changes in climate may drive these species into sub-tropical waters. The discovery, therefore, of small box jellyfish in the waterways of the Gold Coast and Sunshine Coast of south-east Queensland raised concern. This pygmy species proved to be new to science, separated from other species in the genus Chiropsella by its very small size; its semi-circular phacellae; very shallow, coalesced gastric saccules; its peculiar, long pedalia where the palm is greatly reduced and the nonopposing fingers branch off together at the same level; and a knee-like bend of the pedalial canal. The residential canal/ river habitat of this species of chirodropid raises the question of whether this area is also suitable for habitation by the larger, more virulent chirodropids such as the so-called deadly box jellyfish, Chironex fleckeri. This new species, Chiropsella saxoni sp. nov., brings the total number of chirodropid species described from Australian waters to five.

热带箱型水母（Tropical box jellyfish）囊括了全球毒性最强的部分动物类群，因此研究者与媒体均关注气候变化是否会推动此类物种向亚热带海域扩张。正因如此，在昆士兰州东南部黄金海岸与阳光海岸的水域中发现小型箱型水母的事件引发了学界担忧。经鉴定，该矮小型类群为科学新种，其与手曳水母属（Chiropsella）其他物种的鉴别特征包括：体型极度微小；呈半环形的触须囊（phacellae）；极浅且相互融合的胃囊（gastric saccules）；形态特殊的细长足盘（pedalia）——其掌部显著退化，无对生的指状结构于同一水平处共同分出；以及足盘管（pedial canal）呈膝状弯曲。该手曳水母类（chirodropid）物种栖息于住宅运河与河道生境，这一发现引发了新的疑问：该区域是否同样适宜体型更大、毒性更强的手曳水母类物种栖息，例如被称为“致命箱型水母”的澳大利亚箱形水母（Chironex fleckeri）。此次描述的新种萨克逊手曳水母（Chiropsella saxoni sp. nov.），使澳大利亚海域已正式记录的手曳水母类物种总数增至5种。