Petalophthalmus Willemoës-Suhm, 1875

Vicente, Carlos San & Corbari, Laure, 2015, A new bathyal mysid of the family Petalophthalmidae (Crustacea: Mysida) from the Bismarck Sea (Western Tropical Pacific Ocean), Zootaxa 3925 (2), pp. 241-256 : 253

Key to species of Petalophthalmus Willemoës-Suhm, 1875

An identification key (modified from Panampunnayil 1982, Wang 1998, San Vicente et al. 2014) is proposed to include the new species herein described.

1. Eyes flattened and leaf-like, without eyestalks and without functional visual elements............................... 2

- Eyes not flattened, with cornea more or less globular in shape, with eyestalks and functional visual elements............. 3

2. Eyes with ocular papilla near the middle inner dorsal margin........ P. papilloculatus San Vicente, Frutos and Cartes, 2014

- Eyes without ocular papilla.................................................. P. armiger Willemoës-Suhm, 1875

3. Eye cornea globular, eyestalk shorter than the cornea, cornea with ocular papilla. Telson apex without pappose setae.......................................................................................... P. papuaensis sp.nov.

- Eye cornea hemispherical or reniform, eyestalk subequal or slightly longer than the cornea, cornea without ocular papilla. Tel- son apex with pappose setae............................................................................ 4

4. Eyestalk with ocular papilla near the middle inner dorsal margin............................... P. oculatus Illig, 1906

- Eyestalk without ocular papilla........................................................................... 5

5. Eye cornea hemispherical; telson apex emarginated in the median region and lateral margins with 12–15 setae increasing in length backwards.............................................................. P. caribbeanus Tattersall, 1968

- Eye cornea reniform. Telson apex not emarginated in the median region; lateral margins with more than 15 subequal setae.. 6

6. Apex of rostral plate slightly pointed. Eyestalk subequal in length to cornea. Telson apex armed with three serrate setae.................................................................... P. macrops Tchindonova and Vereshchaka, 1991

- Apex of rostral plate blunt. Eyestalk longer than cornea. Telson apex armed with seven serrate setae..... P. liui Wang, 1998