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Fishery Bulletin 96(4), 1998 
this analysis). Seven synapomorphies define this 
group as monophyletic (Fig. 6): absence of a dentary 
fossa (55, Fig. 9, C and D); and absence ofceratohyal 
foramen (56) are both autapomorphic for Pleuro- 
nectinae; mesethmoid and blind-side prefrontal are 
sutured but without a foramen between these bones 
(14, Fig. 8D); a double supraoccipital crest forms a 
groove for insertion of anterior dorsal-fin ptery- 
giophores (38, Fig. 10, C-E); a single row of teeth on 
lower jaw (41); intercalar in contact with basioccipi- 
tal (57, Fig. 70; and presence of a posterior exten- 
sion of supratemporal branch of the lateral line (58). 
Some of these character states are not found in all 
pleuronectines, but the occurrence of these states at 
basal lineages and their predominance within the 
Pleuronectinae indicates that the absence of these 
synapomorphies within the subfamily are instances 
of evolutionary reversal. For example, the presence of 
a supratemporal branch (58) is observed in 11 
pleuronectine taxa and is hypothesized to arise at this 
node with two secondary losses observed in more ad- 
vanced lineages within Microstomini and Pleuronectini. 
Intrarelationships of Pleuronectinae The Pleuro- 
nectinae is classified into 4 tribes: Psettichthyini, 
Isopsettini, Microstomini, and Pleuronectini (Fig. 6). 
Branchial structure and characters associated with 
jaw asymmetry determine the interrelationships of 
these tribes. 
Tribe Psettichthyini Genus Psettichthys Mono- 
typic with only P. melanostictus , this lineage is unique 
within the Pleuronectinae, having six distinct char- 
acters (Fig. 6): dorsal fin rays are elongated beyond 
dorsal-fin membrane, an autapomorphy for the spe- 
cies (59); second and third basibranchials are sutured 
(5, Fig. 3A), a reversal within Pleuronectidae; teeth 
are not uniform in length (16); greater than seven 
infraorbital bones (51); gill rakers on fourth 
epibranchial present (40); and one row of teeth on 
upper jaw (60). 
These morphological states are shared with taxa 
both within and prior to the Pleuronectinae. This evi- 
dence clearly positions Psettichthyini as a basal tribe 
of the Pleuronectinae. A suture between the second and 
third basibranchials is observed elsewhere only in 
Limanda punctatissima. Tooth length is uniform in 
other pleuronectine taxa. An increase in infraorbital 
number is observed in two other pleuronectine species, 
Lepidopsetta bilineata and Pleuronichthys decurrens, 
as well as in Cleisthenes, Hippoglossoides , and 
Hippoglossus stenolepis. The presence of gill rakers on 
the fourth epibranchial is found elsewhere only in 
Cleisthenes and Eopsetta. A single row of teeth on the 
upper jaw is observed in all species of the Pleuronectini, 
and in Glyptoeephalus and Microstomus. 
The second lineage contains the newly defined 
tribes Isopsettini, Microstomini, and Pleuronectini. 
Taxa within this lineage are characterized by 11 
synapomorphies (Fig. 6): one gill raker at proximal 
base of second and third epibranchials (30, 31, Fig. 
3D); blind-side premaxilla protruding past the sag- 
ittal axis at its symphysis with that of ocular side 
(61, Fig. 9, C and D); ocular-side premaxilla much 
longer than that of blind side (62, Fig. 9, C and D); 
ventral posterior curvature on blind-side premaxilla 
is present (63, Fig. 9, C and D); asymmetry in space 
between dentary and articular such that blind-side 
space is larger than on ocular side (64, Fig. 9, C and 
D); dorsoposterior process of ocular-side dentary 
larger than its blind-side counterpart (65, Fig. 9C); 
teeth on both ocular-side premaxilla and dentary 
reduced (66, 67, Fig. 9, C and D); epiotic processes 
present (68, Fig. 10, D and E); and ocular-side 
entopterygoid larger than that of blind side (69, Fig. 
2, C and D). 
Distribution of these character states is not without 
exceptions or homoplasies. Reduction of gill rakers on 
the second epibranchial was not observed in Limanda 
(Fig. 30, and a reduction of gill rakers on the third 
epibranchial was not observed for Pleuronectes 
quadrituberculatus . These reductions are homoplastic 
in Hippoglossus and Verasper (Hippoglossinae). 
The third lineage indicating a sister relationship 
between the tribes Microstomini and Pleuronectini, 
is based on six synapomorphies (Fig. 6): within this 
lineage there is an evolution of dentition, from 
pointed or bluntly conical teeth to incisorlike or even 
molariform teeth with uniform cutting edges (70); 
sphenotic process positioned high on sphenotic (37, 
Fig. 7, B and C); urohyal with strongly bifurcate car- 
diac apophysis (39, Fig. 12, D-F); blind-side 
pterosphenoid and prootic form dorsal margin of 
anterior prootic foramen (47, Fig. 7, B and C); me- 
dial margin of fifth ceratobranchial slightly curved 
(71, Fig. 3C); and teeth on fifth ceratobranchial 
bluntly pointed (72, Fig. 30. 
Exceptions to the distribution of character states 
within the third lineage are observed in few species 
and appear to be cases of reversal. They do not con- 
tradict the sister relationship between Microstomini 
and Pleuronectini. The sphenotic process is not posi- 
tioned high on the sphenotic in Glyptoeephalus . A 
strongly bifurcated cardiac apophysis on the urohyal 
was not found in Limanda punctatissima, Pleuro- 
nichthys ritteri, P. ocellatus, and Parophrys vetula. 
These two morphological characters are homoplas- 
tic in Verasper (Hippoglossinae). The sphenotic forms 
the dorsal margin of the anterior prootic foramen on 
the blind side (47, Fig. 7A) in Limanda ferruginea, 
L. proboscidea, Microstomus achne, M. kitt, Glypto- 
