Figure I. Comparison of mtDNA control region sequence from Acipenser sturio and the Atlantic and Gulf of Mexico subspecies of
Acipenser oxyrinchus. Alignment begins nine nucleotides upstream of the terminal association sequence (TAS 1) of tRNA proline. The
position of the polymorphic sites observed among all 159 specimens of A. oxyrinchus are highlighted in bold. The position of the three
fixedsitesbetween thesubspecies ofA. oxyrinchusare noted byasterisks.
ica.Acipensersturio,which once had asimilarly
broadrange inEurope andAsia, nowoccursonly in
very low abundances in both the Gironde River,
France, and theBlack Sea(Rochard et al.1990).
Someworkers have considered theAtlanticstur-
geon to besynonymouswith or asubspecies ofA.
sturio(Scott &Scott1988,BirsteinI993), but Vla-
dykov &Greeley(1963) andMagnin(1964) recom-
mended they be given separate specific status.
pending additional research. Weobtained atissue
samplefrom oneA. sturiospecimencaptured dur-
ing 1994 in theGirondeRiver. We thencompared a
portion(203 bp) of thecontrolregion ofmtDNA
betweenA. sturioandA. oxyrinchus
We found a minimum of 31, and a maximum of 33
nucleotide substitutionsbetween theindividual of
A. sturioand 159 individuals ofbothsubspecies of
A. oxyrinchus (Figure 1).Threesitesalsoexhibited
nucleotideadditions ordeletions. In comparison,
the number ofnucleotide substitutions between
any pair ofspecimens of the twosubspecies ofA.oxyrinchusrangedbetweenfive andeight,with no
additions ordeletions. Excluding additions or dele-
tions.nucleotide divergencebetweenA. oxyrinchus
andA. sturiowas approximately 15%, muchhigher
than the maximum of 3.5% between two subspecies
ofA. oxyrinchus (Ong et al. 1996). There are no un-
ambiguous criteria for theinterpretation ofmole-
culardata indeterminingtaxonomicstatus (e.g.,
O’Brien & Mayr1991,Wayne1992).However, we
believe that the level of differentiation observed ar-
guesstrongly forfullspeciesstatus ofeach of the
western and eastern Atlanticsturgeons.
Scaphirhynchus suttkusi(Alabama sturgeon) has
recently been described (Williams & Clemmer
1991);thisexceedinglyrarespecies isrestricted to
the Mobile River basin ofAlabama andMississippi.
Scaphirhynchussuttkusiare morphologicallysimi-
lar to S. platorynchus (shovelnose sturgeon). but
differsignificantly in sixmeristic and at least eleven
mensuralvariables. Theextent ofgeneticsimilarity
betweenS. suttkusi (one specimen) and S. platoryn-