Parasitic isopods infecting cultured Macrobrachium lanchesteri (De Man, 1911) freshwater prawns in Thailand, including a novel species, Tachaea kamphaengsaenensis sp. n.

The discovery of parasitic isopod Tachaea kamphaengsaenensis sp. n. on freshwater prawn Macrobrachium lanchesteri (De Man, 1911) is described herein. It was found through an extensive survey of cultured and natural ponds in six provinces of Thailand: Bangkok, Chonburi, Nonthaburi, Suphan Buri, Pathum Thani, and Nakhon Pathom. This parasitic isopod species exerts detrimental effects on the prawn’s exoskeleton and damages its eggs. The morphology of Tachaea kamphaengsaenensis sp. n. is distinguished from other species in the genus by the distinct pattern of the setae on the pereopods, pleopods, and maxillipeds. This species also differs morphologically from the other Tachaea species previously reported in Thailand. Furthermore, molecular data analysis reveals a monophyletic divergence from T. chinensis and T. spongillicola . This paper presents the first documented occurrence of T. kamphaengsaenensis sp. n., marking the first record of this parasite in M. lanchesteri and the second record of a prawn-parasitic isopod in Thailand.