Cypriconcha

Key to the known species of Cypriconcha

1 Masticatory surface of mandible with molar-shaped processes ................................................................................... 2

- Masticatory surface of mandible without molar-shaped processes.................................................................... C. alba

2 Length of valves attaining to 3.4 mm.......................................................................................................................... 3

- Length of valves between 3.4–4.2 mm; freshwater or saline ...................................................................................... 5

3 Carapace sub-quadrate in shape, dorsal margin straight; duplicature broad, line of concrescence well defined; radial pore canals abundant ................................................................................................................................................... 4

- Carapace elongate, bean-shaped in lateral view; dorsal margin concave; without radial pore canals .................................................................................................................................................................................. C. hypsophila n. sp.

4 Anterior end of carapace rounded, posterior end slightly rounded to truncated; uncommon, found only in freshwater............................................................................................................................................................. C. pseudoingens

- Both anterior and posterior ends rounded, not truncated; restricted to playa lakes....................................... C. ingens

5 Carapace regularly rectangular in shape and strongly arched posterodorsally............................................... C. steveni

- Carapace subrectangular in side view, anterior and posterior acutely pointed ............................................................ 6

6 Natatory setae of An2 nonplumose and not reaching the apical claws................................................. C. gnathostoma

- Natatory setae of An2 reaching at least the apical claws.............................................................................................. 7

7 Length of anterior seta of caudal ramus less than one-half length of posterior claw ................................... C. barbata

- Length of anterior seta of caudal ramus at least half length of posterior claw................................................ C. macra