Mastigodiaptomus, Light, 1939

Eliâas-Gutieârrez, Suaârez-Morales M., 2000, Two new Mastigodiaptomus (Copepoda, Diaptomidae) from southeastern Mexico, with a key for the identi ® cation of the known species of the genus, Journal of Natural History 34 (5), pp. 693-708 : 706-707

Key to species of Mastigodiaptomus

Males

1a Spine on segment 16 strongly developed. Second basipod of right ®fth leg with a proximal subrectangular projection and two small bulb-like processes along inner margin.................... M. reidae

1b Spine on segment 16 absent or reduced, processes on second basipod not as described above.................... 2

2a Large (over 2,2 mm, excluding furcal rami)........... 3

2b Small or medium-sized (less than 2.0 mm length, excluding furcal rami).... 4

3a First exopod of right ®fth leg with a transverse ridge; antepenultimate segment of right antennule with fang-like process.......... M. purpureus

3b First exopod of right ®fth leg with tongue-like projection. antepenultimate segment of right antennule with rounded, knob-like process....... M. maya

4a Second exopod of right ®fth leg with lateral spine long, at least 75% of length of its segment..................... 5

4b Second exopod of right ®fth leg with lateral spine short: less than half the length of segment..................... 7

5a Second basipod of right ®fth leg with posterior butter¯y-like sclerotization on inner margin................. M. albuquerquensis

5b Same structure without such sclerotization............ 6

6a Left ®fth leg exopod with distal process smooth, right endopod not reaching distal margin of ®rst endopodal segment............ M. nesus

6b Left ®fth leg exopod with distalmost process denticulate, right endopod reaching the distal margin of ®rst endopodal segment......... M. texensis

7a Second exopod of right ®fth leg with a semicircular transverse lamella on proximal posterior surface and a ®ne longitudinal`y’ shaped longitudinal ridge. Lateral spine inserted on second third of segment......... M. montezumae

7b Second exopod of right ®fth leg without a lamella or ridges on proximal posterior surface. Lateral spine subterminal.......... M. amatitlanensis