New material from the Marquesas Islands and other localities of French Polynesia provided 12 thalassinidean species treated in this work, five of which are new to science. There are four species of Axiidae: Acanthaxius spinosissimus (Rathbun, 1906), Axiopsis pica Kensley, 2003, Axiopsis consobrina de Man, 1905, Calaxius sibogae (de Man, 1925); one of Strahlaxiidae: Neaxius trondlei n. sp.; two of Thomassiniidae: Crosniera dayrati n. sp., Mictaxius salvati n. sp.; four of Callianassidae: Callianassa amboinensis de Man, 1888, Corallianassa coutierei (Nobili, 1904), Neocallichirus frouini n. sp., Cheramus sibogae (de Man, 1905); and one of Upogebiidae: Gebiacantha albengai n. sp. Neaxius trondlei n. sp. is differentiated by article 2 of antennal peduncle with one or two upper spines, unarmed laterally; merus of pereopod 2 and 3 unarmed on lower border; telson with three well marked transverse carinae equally distant from one another. Crosniera dayrati n. sp. is differentiated by a non spike-like, triangular rostrum, non flattened eyestalks with terminal corneas, elongate telson and uropods. Mictaxius salvati n. sp. is hermaphrodite and has abdominal pleuron 1 rounded posteroventrally, approximately quadrate telson with posterior border nearly straight, uropod exopod not bilobed. Neocallichirus frouini n. sp. is characterised by major pereopod 1 merus with prominent lower expansion bearing large spines, maxilliped 3 with non quadrate propodus. Gebiacantha albengai n. sp. differs in having a rostrum nearly twice as long as wide with three infrarostral spines, single spine on anterolateral border of carapace, pereopod 1 propodus unarmed on mesial surface.
Crustacea, Decapoda, Thalassinidea, French Polynesia, new species.