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Fishery Bulletin 96(4), 1998 
smaller number of teeth on the ocular-side premax- 
illa than the number observed in previous lineages 
of Pleuronectinae (Norman, 1934). Glyptocephalus 
cynoglossus is reported to have 8 to 15 teeth on the 
ocular-side premaxilla and 17 to 26 on the associ- 
ated blind-side premaxilla. G. stelleri has only seven 
teeth on the ocular-side premaxilla and 20 to 27 teeth 
on the blind side. G. tanakius has 12 to 14 teeth on 
the ocular-side premaxilla and 14 to 16 on the blind 
side, and G. zachirus has 12 to 16 teeth on the ocu- 
lar-side premaxilla and 20 to 27 teeth on the blind 
side (Norman, 1934). 
The third lineage of Microstomini indicates mono- 
phyly for Pleuronichthys, Microstomus, and Glypto- 
cephalus. It is based on ten character transforma- 
tions, four synapomorphies, and six reversals (Fig. 
15). Synapomorphies include increased number of 
abdominal vertebrae to between 12 and 14 (23); lips 
thickened or fleshy (76); palatine of ocular side re- 
duced and not attached to pterygoid (28, Fig. 20; 
and teeth on ocular-side dentary reduced to fewer 
than six (67). The reversals are exoccipital and prootic 
in contact with each other (77, Fig. 7B); presence of 
an interorbital process (17, Fig. IOC); one row of gill 
rakers on fourth ceratobranchial (21, Fig. 3, A and 
B); haemal spine broadly attached to centrum (73, 
Fig. 5B); space between both ocular- and blind-side 
dentary and articular equal in size (64, Fig. 9D); and 
dorsoposterior process of similar size on ocular- and 
blind-side dentaries (65, Fig. 9D). 
Exceptions and homoplasy in this distribution do 
not support an alternative hypothesis. Glypto- 
cephalus kitaharai has only 11 abdominal vertebrae 
(Sakamoto, 1984a). Reduction of the ocular-side pa- 
latine was also observed in Hippoglossus and 
Verasper (Hippoglossinae). The exoccipital and 
prootic are not joined, and secondary reduction of 
teeth on the dentary of the ocular side are not ob- 
served in Glyptocephalus . These species all have pro- 
portionally fewer teeth on the ocular-side dentary, 
but the exact number ranges from 11 to 15 in 
Glyptocephalus kitaharai to 10 to 18 in G. zachirus 
(Norman, 1934). 
Reversals in this lineage reproduce plesiomorphic 
states observed prior to the fourth lineage of 
Pleuronectidae or states that are plesiomorphic 
within the Pleuronectinae. The contact between 
exoccipital and prootic, may be a reversal for the fam- 
ily. The lost interorbital process in the fourth 
pleuronectid lineage is observed (at least partially) 
in these two pleuronectine genera. The single row of 
gill rakers on the fourth ceratobranchial is a rever- 
sal of the two rows that define the fourth pleuronectid 
lineage. The broad attachment of the haemal spine 
to the centrum is a reversal of a narrower attach- 
ment defining the fourth pleuronectid lineage. Sym- 
