Idiosepius thailandicus is a species of bobtail squid native to the Indo-Pacific waters off Thailand. The extent of this species' distribution is still to be determined and records of Idiosepius dwarf squid away from Thailand, south to Indonesia and north to Japan, may be attributable to this species.
In the Gulf of Thailand off eastern Thailand Idiosepius thailandicus was recorded among seaweed in the littoral zone in Rayong Province and in a mangrove habitats in Chanthaburi Province. In mangrove habitats the squid adhered their eggs to the roots of the mangrove. In the Andaman Sea, ths species occurred in subtidal seagrass beds near the mouth of eastuaries lined with mangroves and on sand bars which were interspersed with rocks. In these habitats the eggs were attached to the underside of blades of seagrasses. These squids and their relatives have a glue gland on their dorsal body surface that they use to adhere to submerged vegetation and other objects. Their life cycle is thought to include a juvenile pelagic stage.
Idiosepius thailandicus is classified as Data Deficient by the IUCN as its exact distribution is unknown and no assessments have been made of its population size or population trends. The seagrass beds which form an important part of this species habitat are under threat and if, as may be the case, this species extends north to Japan then the seagrass beds there have been severely negatively impacted by human activities.
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- Chotiyaputta, C., T. Okutani & S. Chaitiamvong 1991. A new pygmy cuttlefish from the Gulf of Thailand Idiosepius thailandicus n. sp. (Cephalopoda: Idiosepiidae). Venus, the Japanese Journal of Malacology 50(3): 165-174.
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- Current Classification of Recent Cephalopoda