Petalophthalminae, Czerniavsky, 1882

Forman, Jeffrey S. & Schnabel, Kareen E., 2021, Two new species of Petalophthalmus and Ipirophthalmus (Crustacea: Mysida: Petalophthalmidae), from New Zealand, Zootaxa 5061 (3), pp. 451-475 : 472-473

Key to the genera and species of the subfamily Petalophthalminae

This key is modified from Panampunnayil 1982, Wang 1998, San Vicente et al. 2014, San Vicente & Corbari 2015, and Wittmann, 2020 and is proposed to include the two new species described herein.

1. Outer margin of antennal scale naked, ending in a single spine.................................................. 2

- Antennal scale setose all around.......................................................................... 4

2. Thoracic endopods 6–8 rudimentary, 1–2 articlulate; thoracic endopods 3–5 ending in 2 short setae; eyestalk elongated, without papilla, ( Parapetalophthalmus Murano & Bravo, 1998 ; monotypic).................................................................................................... Parapetalophthalmus suluensis Murano & Bravo, 1998

- Thoracic endopods 3–8 with more than 4 articles ending in a strong claw; third article of mandibular palp with seven long, strong setae; ( Pseudopetalophthalmus Bravo & Murano, 1997 )................................................ 3

3. Telson with 4 setae on lateral margin; thoracic endopods 3–5 with carpopropodus longer than merus........................................................................... Pseudopetalophthalmus australis Panampunnayil, 1982

- Telson with 7–8 setae on the lateral margin; thoracic endopods 3–5 with carpopropodus longer than merus.................................................................... Pseudopetalophthalmus japonicus Bravo & Murano, 1997

4. Eyes globular or flat, without distinct cornea; terminal margin of telson without long plumose setae ( Petalophthalmus Willemoes-Suhm, 1875 )............................................................................... 5

- Eyes with distinct cornea with functional visual elements; telson apex with four plumose setae ( Ipirophthalmus Wittmann 2020 )............................................................................................... 9

5. Eyes globular, with eyestalks, cornea with irregularly distributed retinular cells......................................................................................... Petalophthalmus papuaensis San Vicente & Corbari, 2015

- Eyes flattened and without functional visual elements........................................................ 6

6. Rostrum absent; anterior margin of carapace truncate; telson with 25–37 setae on the distal 2/3 of lateral margin....................................................... Petalophthalmus papilloculatus San Vicente, Frutos & Cartes, 2014

- Rostrum present, acute................................................................................. 7

7. Eyes leaf-like; thoracic endopod 5 with preischium, ischium, and merus subequal in length; carpus and propodus subequal; telson with.................................................. Petalophthalmus armiger Willemoes-Suhm, 1875

- Eyes elongate, ovoid; merus of thoracic endopod 5 longer than ischium.......................................... 8

8. Eyes dorsoventrally flattened by a factor of 1.4; merus of thoracic endopod 2 with 5 large setae on outer margin, carpopropodus with 3 long and 6 short setae on the outer margin; merus of thoracic endopod 5 longer than combined preischium and ischium; carpus less than half length of propodus................................. Petalophthalmus cristatus Wittmann, 2020

- Eyes laterally flattened; elongated ventilation lobe on 7 th oostegites; merus of thoracic endopod 2 with 6 large setae on inner margin; merus of thoracic endopod 5 subequal to preischium and ischium combined; carpus subequal to propodus.................................................................................. Petalophthalmus lobatus sp. nov.

9. Thoracic endopods 6–8 rudimentary, shorter than proximal article of exopod............ Ipirophthalmus crusulus sp. nov.

- Thoracic endopods 6–8 comprised of 4 or more articles, longer than proximal article of exopod...................... 10

10. Cornea hemispherical or reniform, covering less than half of lateral margin of eyestalk; telson apex emarginate.......... 11

- Cornea reniform, covering more than half of lateral margin of eyestalk; telson apex not emarginate................... 12

11. Telson with 12–15 setae on the lateral margins; eye cornea reniform; eyestalk without ocular papilla; scale shorter than antenna; female pleopods biramous....................................... Ipirophthalmus caribbeanus O.S. Tattersall, 1968

- Telson with 17–18 setae on the lateral margins; eye cornea hemispherical; eyestalk with ocular papilla; scale longer than antenna; female pleopods uniramous.......................................... Ipirophthalmus oculatus Illig, 1906

12. Telson with 16–19 setae on the lateral margins, combined width of eyes subequal to carapace width; antennal scale with apical lobe....................................................................... Ipirophthalmus liui Wang, 1998

- Telson with 21–22 setae on the lateral margins; eyes very large, combined width wider than carapace width; antennal scale without apical lobe.................................... Ipirophthalmus macrops Tchindonova & Vereshchaka, 1991