Heteromysinae

Vicente, Carlos San & Monniot, Françoise, 2014, The ascidian-associated mysid Corellamysis eltanina gen. nov., sp. nov. (Mysida, Mysidae, Heteromysinae): a new symbiotic relationship from the Southern Ocean, Zootaxa 3780 (2), pp. 323-346 : 340-341

Key to the genera and subgenera of Heteromysinae

(modified from Modlin 1984; Bowman & Orsi 1992; and Bravo & Murano 1996)

1. Third thoracopod endopod with some of the distal segments enlarged. Telson with apical cleft........................ 2

- Third thoracopod endopod without some of the distal segments enlarged. Telson with or without apical cleft............. 9

2. Body isopod-like, dorsoventrally flattened. Pleonites with well developed pleura............. Platymysis Brattegard, 1980

- Body not dorsoventrally flattened. Pleonites without well developed pleura........................................ 3

3. Eyes reduced, restricted to distolateral part of eyestalk................................ Heteromysoides Bacescu, 1968

- Eyes well developed, occupying full width of distal part of eyestalk.............................................. 4

4. Fourth thoracopod endopod with several weakly modified setae on the carpus, with apically bifid claw. Eighth male thoracic endopod with modified flagellate setae on the outer margin of the ischium, with a strong spiniform extension of the preischium.............................................................................. Ischiomysis Wittmann, 2013

- Fourth thoracopod endopod without modified setae on the carpus, without apically bifid claw. Eighth male thoracic endopod without modified setae on the outer margin of the ischium, without spiniform extension of the preischium............... 5

5. Females with large sternal plate in traverse orientation, emerging from the eighth sternite. Terminal segment of male antennula with modified setae with a roughly navicular portion armed on only one side with numerous tubercles and teeth on the upper mediodistal corner............................................................... Retromysis Wittmann, 2004

- Females without sternal plate emerging from the eighth sternite. Terminal segment of male antennula without modified setae or with modified without a roughly navicular portion (genus Heteromysis S.I. Smith, 1873 )......................... 6

6. Third thoracic endopod very robust, greatly inflated; merus enlarged, dentate; exopod reduced. Endopod of uropod longer than exopod.............................................................. H. ( Gnathomysis ) Bonnier & Perez, 1902

- Third thoracic endopod only moderately robust. Endopod of uropod shorter than exopod............................ 7

7. Pleopods not sexually dimorphic. Pleon with medial sternal processes..................... H. ( Heteromysis ) Smith, 1873

- Fourth pleopods sexually dimorphic. Pleon without medial sternal processes....................................... 8

8. Antennule with two modified setae on distomedial corner of third segment, medial seta linguiform with subterminal flagellum, lateral seta simple, very long, directed laterally...................................... H. ( Olivemysis ) Bacescu, 1968

- Antennule with two pairs of simple setae on distomedial corner of third segment, pairs diverging from each other. Fourth pleo- pod with the two apical setae longer than the fourth pleonite........................ H. ( Neoheteromysis ) Bacescu, 1976

9. Telson with clear apical cleft........................................................................... 10

- Telson without or with minute apical cleft................................................................. 14

10. Male pleopod 3 very long, 2-segmented............................................. Harmelinella Ledoyer, 1989

- Male pleopod 3 rudimentary, unsegmented................................................................ 11

11. Penes extremely thick, large to giant in length; provided with erectile capability due to a variously folded cuticle......................................................................................... Mysifaun Wittmann, 1996

- Penes without variously folded cuticle.................................................................... 12

12. Eyes without cornea......................................................... Burrimysis Jaume & Garcia, 1993

- Eyes with well-developed cornea........................................................................ 13

13. Inner margin of endopod uropod with row of cuspidate setae (except M. hanseni Zimmer, 1914 ).................................................................................................. Mysidetes Holt & Tattersall, 1906

- Inner margin of endopod uropod without cuspidate setae........................ Bermudamysis Bacescu & Iliffe, 1986

14. Inner margin of endopod uropod without cuspidate setae..................................................... 15

- Inner margin of endopod uropod with row of cuspidate setae.................................................. 17

15. Eye strongly dorso-ventrally flattened, with latero-external visual part. Telson armed with three lateral setae......................................................................................... Platyops Bacescu & Iliffe, 1986

- Eyes normal. Telson armed with 4–6 lateral setae........................................................... 16

16. Eye cornea narrower than the eyestalk. Antennal peduncle much longer than the antennal scale, with the distal two segments subequal in length; antennal scale without distal transverse suture. Male second thoracic endopod with notches on outer margin Kochimysis Panampunnayil & Biju, 2007

- Eye cornea as wide as the eyestalk. Antennal peduncle as long as the antennal scale, with the third segment longer than the second one; antennal scale with a distal transverse suture. Male second thoracic endopod without notches on outer margin.............................................................................. Deltamysis Bowman & Orsi, 1992

17. Eyes with definite eyestalks. Distal segment of endopod of maxilla with five very powerful triangular spines strongly serrated. Endopod of thoracopods 5–8 slender and feeble. Telson long and narrow............... Pseudomysidetes Tattersall, 1936

- Eyes without eyestalks. Distal segment of endopod of maxilla without powerful spines. Endopod of thoracopods 7–8 forming a powerful subchela. Telson linguiform.................................................. Corellamysis gen. nov.