Cooper and Chapleau: Monophyly and intrarelationships of the family Pleuronectidae 
719 
sakhalinensis, L. proboscidea, L. punctatissima, 
Pseudopleuronectes americanus, P. herzensteini, 
P. obscurus (not examined), P. schrenki, and P. 
yokohamae on the basis of the oldest valid genus- 
group name for each species, with the exception 
of Pseudopleuronectes schrenki , and P. obscurus, 
previously classified as Limanda schrenki 
(Sakamoto, 1984b; Hensley and Ahlstrom, 1984) 
and Liopsetta obscura (Norman, 1934), respec- 
tively Sakamoto’s (1984a) classification was based 
on a 100% similarity observed among these 19 
species. The new phylogeny is based on 67 addi- 
tional morphological features that clearly differ- 
entiate and classify these 19 species. 
6 The reclassification of Pseudopleuronectes 
schrenki is based on its position in all 128 most 
parsimonious trees, none of which united P. 
schrenki with other taxa exclusive of the three 
other species in Pseudopleuronectes . In addition 
to the three synapomorphies uniting Pseudo- 
pleuronectes, the most notable characteristic of 
P. schrenki in observation and in the literature is 
the presence of incisorlike teeth that form a con- 
tinuous cutting edge (character 70, Fig. 9D, see 
also Sakamoto, 1984b). This character defines the 
fourth lineage of Pleuronectini, uniting Pseudo- 
pleuronectes and Pleuronectes, and excludes the 
other species of Limanda that have teeth with 
truncated tips or are bluntly conical (70, Fig. 90. 
A review of literature describing Pseudopleuro- 
nectes schrenki (= Limanda schrenki) indicates a 
close relationship with P. yokohamae (= Limanda 
yokohamae) (Jordan and Starks, 1906). Norman 
(1934) synonymized Limanda schrenki under 
Pseudopleuronectes yokohamae. Studies dealing 
with egg characteristics also seem to synonymize 
Pseudopleuronectes schrenki with P. yokohamae 
(Yusa, 1960; Pertseva-Ostroumova, 1961). Recent 
studies (Sakamoto, 1984b) indicate that P. 
schrenki (= Limanda schrenki) is a valid species 
with similar characteristics to P. yokohamae 
(= Limanda yokohamae). Meristic counts of ver- 
tebrae, dorsal- and anal-fin rays are overlapping 
(Sakamoto, 1984a, 1984b). They also have simi- 
lar dental structure. However, P. schrenki has a 
distinct pattern of bars on the dorsal- and anal- 
fin rays (Sakamoto, 1984b). Uncertainty sur- 
rounding the status of Pseudopleuronectes 
schrenki is also the result of the ineffective use of 
nomenclature. As illustrated in the above refer- 
ences, the classification of Pseudopleuronectes 
yokohamae as Limanda yokohamae, has led to a 
degree of confusion, further supporting the need 
to clearly identify natural groups on the basis of 
uniquely derived features. Although a further 
analysis is required to clearly assess the taxo- 
nomic status of Pseudopleuronectes schrenki and 
P. yokohamae, this analysis clearly indicates that 
neither should be classified as Limanda. 
7 The reclassification of Pseudopleuronectes 
obscurus is based solely on information available 
from the literature. This species is confidently 
placed in the fourth lineage of Pleuronectini and 
its placement as a species of Pseudopleuronectes 
is supported by one synapomorphy, the presence 
of a demersal egg. A complete osteological exami- 
nation of this species may test the validity of this 
classification. 
Acknowledgments 
We gratefully acknowledge the following institutions 
and their scientific staff for the loan of specimens: C. 
B. Renaud, S. Laframboise and J. Frank (Canadian 
Museum of Nature, Ottawa), R. Winterbottom and 
E. Holm (Royal Ontario Museum, Toronto), D. W. 
Nelson (University of Michigan Museum of Zoology, 
Ann Arbor), B. Chernoff and M. A. Rogers (Field 
Museum of Natural History, Chicago), S. L. Jewett 
and S. J. Raredon (National Museum of Natural His- 
tory, Smithsonian Institution, Washington, D.C.), W. 
F. Smith- Vaniz and S. A. Schaefer (Academy of Natu- 
ral Sciences, Philadelphia), T. Iwamoto (California 
Academy of Sciences, San Francisco), L. Van Guelpen 
(Atlantic Reference Center, St. Andrews), T. W. 
Pietsch, A. M. Snyder, and M. L. Lonzarich (Univer- 
sity of Washington, Seattle), K. Amaoka (Hokkaido 
University Laboratory of Marine Zoology, Hakodate), 
M. McGrouther (Australian Museum of Science, 
Sydney), and M. Desoutter (Museum national 
d’Histoire naturelle, Paris). This work was supported 
by an operating grant to F. Chapleau by the National 
Sciences and Engineering Research Council of 
Canada. 
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