686 
Abstract. -a cladistic analysis of 
interrelationships for 53 (of 59) pleuro- 
nectid species was performed by using 
106 morphological and osteological 
characters. The analysis resulted in 128 
equally parsimonious cladograms (heu- 
ristic search, 403 steps, consistency in- 
dex=0.33, retention index=0.79). A 50% 
majority-rule consensus cladogram in- 
dicated that only five of 47 resolved 
nodes were observed in less than 100% 
of the cladograms. These five nodes are 
restricted to interrelationships within 
one subfamily. The Pleuronectidae is 
monophyletic according to ten synapo- 
morphies. In addition, five subfamilies 
were defined: Hippoglossinae, Eopset- 
tinae, Lyopsettinae, Hippoglossoidinae, 
and Pleuronectinae. The largest sub- 
family, the Pleuronectinae, was further 
subdivided into four tribes: Psettich- 
thyini, Isopsettini, Microstomini, and 
Pleuronectini. The interrelationships 
established within Pleuronectidae pro- 
vide a strong foundation for a simpli- 
fied yet phylogenetically informative 
taxonomic nomenclature at the genus- 
group level. The following genera are 
reclassified: Atherestes and Reinhard- 
tius to Reinhardtius', Errex, Glypto- 
cephalus, and Tanakius to Glypto- 
cephalus', Embassichthys , and Micros- 
totnus to Microstom us\ Hypsopsetta and 
Pleuronichthys to Pleuronichthys ; and 
Kareius and Platichthy to Platichthys. 
To preserve the monophyletic status of 
Eopsetta , E. exilis was reassigned to the 
genus Lyopsetta (Lyopsettinae). The 
genus Pleuronectes (as defined by 
Sakamoto in 1984) was found to be 
polyphyletic. Monophyly of this genus 
is established by revising it to include 
only five species; Pleuronectes glacialis, 
P. pinnifasciatus, P. platessus , P. 
putnami, and P. quadrituberculatus . 
Other species, formerly placed in 
Pleuronectes, are now reclassified to 
Isopsetta, Limanda, Parophrys, Pset- 
tichthys, and Pseudopleuronectes. The 
monophyletic status of Limanda (six spe- 
cies) is uncertain because of unresolved 
relationships between these species and 
other taxa in the tribe Pleuronectini. 
Manuscript accepted 10 March 1998. 
Fish. Bull. 96(4): 686-726 ( 1998). 
Monophyly and intrarelationships 
of the family Pleuronectidae 
(Pleuronectiformes), 
with a revised classification 
J. Andrew Cooper 
National Marine Fisheries Service, Systematics Laboratory 
Museum of Natural History, Washington, D.C. 20560-0153 
E-mail address: cooperandrew@nmnh.si.edu 
Francois Chapleau 
Ottawa-Carleton Institute of Biology, Faculty of Science 
University of Ottawa, PO. Box 450, Station A, Ottawa, Ontario, KIN 6N5 
The Pleuronectidae ( sensu Chapleau 
and Keast, 1988) contains 59 nominal 
species of right-eyed flatfishes distrib- 
uted in marine waters of the North- 
ern Hemisphere. As presently com- 
posed, this family excludes the sub- 
families Poecilopsettinae, Samarinae, 
Rhombosoleinae, and Paralichtho- 
dinae, formerly included in Norman 
(1934). It contains many commercial 
species that have long been harvested 
in coastal seas off Europe, North 
America, and Asia. Species such as 
the Petrale sole ( Eopsetta jordani), 
Pacific halibut ( Hippoglossus steno- 
lepis), American plaice ( Hippo - 
glossoides platessoides), and Dover 
sole (Microstomus pacificus), to 
name but a few, are valued for their 
large size and excellent meat (Hart, 
1973; Scott and Scott, 1988). In to- 
tal, there are over 36 species of flat- 
fish monitored by the Food and Ag- 
ricultural Organization of the 
United Nations, with a total annual 
catch of 256,353 metric tons (t) in 
1995 (FAO, 1997). Nearly one half 
(18) of these species are classified 
within the Pleuronectidae (FAO, 
1997 ). Total annual commerical har- 
vest of Pacific halibut (Hippoglossus 
stenolepis) was estimated at 25,968 
t in 1995 a decrease from 40,584 t 
in 1985 (FAO, 1997). A similar situ- 
ation has been observed in witch 
flounder ( Glyptocephalus cyno- 
glossus ) for which 19,537 t was har- 
vested in 1995 as compared to 30, 
074 tin 1985 (FAO, 1997). With few 
exceptions, this decline in annual 
harvest is observed for most pleuro- 
nectid species (FAO, 1997). The 
commercial popularity of pleuro- 
nectid species, coupled with a need 
to manage these renewable re- 
sources, strongly emphasizes the 
necessity for a better understand- 
ing of relationships within this 
group, as well as an informative 
taxonomic nomenclature that will 
provide a framework for manage- 
ment policy. Variation in life history 
traits are observed at many phylo- 
genetic levels. Populations of the 
American plaice ( Hippoglossoides 
platessoides) are recorded to have 
age of maturity ranging from 3 to 
15 years (Roff, 1981). Within the 
family, variation in maximum 
length ranges from 220 mm in 
Dexistes rikuzenius (Sakamoto, 
1984b) to over 2500 mm in Hippo- 
glossus stenolepis (Hart, 1973). An 
hypothesis of species interrelation- 
ships can be used as a framework 
to assess phylogenetic constraint on 
life history traits versus a species’ 
ability to respond to changing envi- 
ronmental conditions (Brooks and 
McLennan, 1991). An assessment of 
