NANFA-- Gambusia affinis vs holbrooki

Hoover, Jan J ERDC-EL-MS (
Fri, 20 Apr 2001 16:19:42 -0500

I want to identify some gambusia that were introduced into some desert
springs in New Mexico. Because both affinis and holbrooki occur naturally in
Alabama, I used the key in Mettee et al, Fishes of Alabama. Characters
according to reference are

distal seg.s of anal ray 3 of gonopodium: affinis, smooth; holbrooki,
number of dorsal rays: affinis, usually 6; holbrooki, usually 8
number of anal rays: affinis, 9; holbrooki, 10

Based on 6 males and 3 females I've looked at so far, characters for my
specimens are, respectively: serrate, 6-7, and 9. They are, then, affinis
meristically, holbrooki, morphologically.

To confuse matters furthur, Steven George and I have looked at mosquitofish
from the Big Sunflower in Mississippi and find that THEY have serrated

My questions are:
How good is the serrated gonopodium character ? Does it occur in affinis ?

Note - I have seen and read the Angus and Howell paper on gambusia which
indicates some degree of interspecific hybridization throughout native
range. Unfortunately their paper does not address the gonopodium character,
and I do not have any primary literature on this.

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