Palaemon debilis Dana, 1852

(Figs. 6, 13D)

Previous Taiwan records. (?) Maki & Tsuchiya 1923: 54, pl. 3-fig. 5.

Material examined. Ludao, Taitung County, 9.VIII.2017, 3 males (pocl 5.1–6.0 mm) (NTOU M02071) , 1 male (pocl 5.5 mm) (NTOU M02086), 1 male (pocl 5.5 mm) (NTOU M02087), 1 male (pocl 4.4 mm) (NTOU M02088).

Diagnosis. Rostrum strongly ascendant distally, tapering gradually; rostral formula 1+5–8/3–10; basal antennular segment with disto-lateral spine falling short of adjacent convex distal margin of segment; free portion of shorter ramus of dorsal antennular flagellum approximately equal in length to fused part; mandible with or without palp, when present 1, 2 or 3 segmented; first pereiopod with carpus more than twice times as long as chela; second pereiopod with carpus more than twice as long as chela; fifth abdominal pleuron acute distoventrally; first pleopod of male without marginal appendix on endopod.

Colour pattern. Body semi-transparent with few brown dots. Rostrum largely brownish. Carapace with some brown stripes. Sixth abdominal somite at bases of uropods with a large brown spot.

Remarks. Palaemon debilis was reported from Taiwan by Maki & Tsuchiya (1923) with this record further cited in Holthuis (1950). The photo in Maki & Tsuchiya (1923) bears a superficial resemblance to P. debilis, but is rather unclear. Nevertheless, the present newly collected material confirms the presence of this species in Taiwan.

Ecology. Fresh, brackish and salt waters.

Distribution. Red Sea to South Africa to Ryukyu Islands, Philippines and Indonesia, Great Barrier Reef of Australia, and eastward to Hawaii and the Tuamotu Archipelago.