Re: NANFA-L-- Micropterus identification

dlmcneely-in-lunet.edu
Wed, 19 Jul 2006 08:24:50 -0500

Hi Dan, great pictures. I'm not a Micropterus expert. However, I've
seen a few of them in my life. One character that you didn't mention,
but that is relevant to-in-least some of your pictures, I think, is
the length of the jaw. In largemouths, the maxilla extends past the
back of the eye, while in spotteds, it extends only to the middle of
the eye. The first two fish you have labeled as largemouths look to
have the largemouth jaw length, BUT, they show other features that
appear to be spotteds, and some that appear to be largemouths. In
spotteds, the "warpaint" streaks on the face are much more prominent
than in largemouths, where they are often imperceptible. Spotteds
usually have, and largemouths usually lack, the rows of spots below
the lateral stripe and in front of the anal fin. Spotteds typically,
but largemouths in some areas, have the lateral stripe broken with the
splotches being deeper than wide(as all the fish in your photos do).
In spotteds, but to a lesser degree in largemouths, the dorso-lateral
dark pigmentation is in the pattern of "vermiculations," best visible
when the fish is seen from above in clear water, difficult to see when
the fish is faded or in air. Some of the fish you have labeled as
largemouths show this feature.

My understanding is that the particular two characters you mentioned,
of dorsal spine length and teeth on the base of the tongue, are
definitive-in-all sizes. The tail coloration of fingerlings is
confusing. If definitely not tricolor, then largemouth. But some
largemouths seem to have a tricolored tail in some places.

It does appear to me that some of the bass you labeled largemouth are
more likely spotteds, but that's based mainly on pigmentation as shown
in the photos. Those particular ones also appear to have a lower
spinous dorsal with a shallower notch between the spinous and soft
dorsal, but that might be posture and camera angle.

Sorry for the length of this post, and the lack of definitiveness.

Dave McNeely

David L. McNeely, Ph.D., Professor of Biology
Langston University; P.O. Box 1500
Langston, OK 73050; email: dlmcneely-in-lunet.edu
telephone: (405) 466-6025; fax: 405) 466-3307
home page http://www.lunet.edu/mcneely/index.htm

"Where are we going?" "I don't know, are we there yet?"

----- Original Message -----
From: Dan Johnson <danjohns-in-io.com>
Date: Tuesday, July 18, 2006 8:08 pm
Subject: NANFA-L-- Micropterus identification
> I'm still trying to get a handle on the Micropterus species in my
> area.
> For reference, check out links to what I've previously identified as
> largemouth bass:
>
> http://www.io.com/~danjohns/fish/largemouth_bass.html
>
> and spotted bass:
>
> http://www.io.com/~danjohns/fish/spotted_bass.html.
>
> The checklist of Freshwater Fish of Texas by Hubbs, et al, states
that
> ratios of largest to smallest dorsal spines are as follows:
>
> 2.4 to 3.9 for salmoides
> 1.1 to 2.5 for punctulatus (and other species)
>
> I have annotated these ratios in the captions for all photos where
> theycould be measured. All fall in the range for punctulatus.
>
> punctulatus have teeth on the tongue, salmoides usually doesn't. The
> two fish on the punctulatus page, which I have preserved, have
> teeth.
> The other fish are not available.
>
> The peterson guide states that young punctulatus have distinct
> tricolored tails as you can see in some of the younger specimens
> on the
> salmoides page. I can't remember the reference, but I read salmoides
> young have a more bicolored tail. Peterson doesn't describe the tail
> for young for salmoides.
>
> I'm starting to wonder if all the fish on my salmoides page are
> actuallypunctulatus. Any opinions from micropterus experts out
there?
>
> Thanks in advance.
>
> --Dan
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