FLOUNDERS OF GENXJS PARALICHTHYS AXD RELATED GENERA 



311 



Geographic distribution. — Besides the localities 

 given above from which specimens were studied 

 (all from the Gulf of California), the species has 

 also been recorded from Magdalena Bay on the 

 west coast of Lower California under tlie name 

 of Paralichthys maydahnae. The present known 

 range of the species is tlierefore from the mouth 

 of the Colorado Eiver to ilagdalena Bay. In the 

 latter localitj- it occui-s together with caHfornieus. 

 It is possible that it extends further north on the 

 west coast of Lower California and that it has 

 been confused there with californiciis. 



Size. — Tlie type of magdalenae, 17 inches, is the 

 largest specimen known of this species. The larg- 

 est specimen examined in this study is 15 inches 

 (381 mm.). 



Distinctive characters and relatianship. — ^As far 

 as the practical work of correctly identifying ma- 

 terial is concerned, it is onlj' necessary to consider 

 the relation of the present species with woolmani, 

 californicux, and H. tetrophtholmiis, since these 

 are the onlj' known species which occur together 

 witli it in parts of its range, with which it may 

 be confused. P. a-estuwiu^ may be distinguished 

 from icoohnani by the number of gill rakers (table 

 4). There is a wide gap in the ranges of the two 

 species, and they may be separated without diffi- 

 culty, at all ages, by that character alone. H. 

 tetrophfhahnus has a still smaller number of gill 

 rakers. The situation becomes difficult, however, 

 when we try to distinguish correctly aestuarvus 

 from californicus, as discussed under the account 

 of the latter. 



This species is evidently closely related to 

 califomicus, nearly agreeing with the latter not 

 only in the number of gill rakers and the number 

 of scales, but also in the almost invariably sinistral 

 or dextral body. The change in the character of 

 the scales of aestuariu-s with age, ctenoid in the 

 small fisli becoming cycloid in the larger indi- 

 viduals, furnishes evidence as to the probable 

 pliylogenetic develo])ment of some species of 

 Paralichthys. Assuming that the loss of spinules 

 on the scales is a more recent development in this 

 genus, it maj' be stated that aestuarius is an off- 

 .shoot of calif oriiicus. As a further development 

 along this line of modification, uxw/nitni! has been 

 dfMJved from aestiiarli/.s. by the loss of .scale 

 .spinules at all ages. "We tlms have evidence to 



show the derivation of the subgenus Chaenopsetta 

 from typical Paralichthys. 



Synonymy. — Tlie species described under the 

 name Paralichthys magdalenae was evidently 

 based on a specimen of aestuanus. Abbott in de- 

 scribing his supposedly new species compared it 

 with californicijs and correctly pointed out the 

 important differences, as far as tlie size of the 

 specimen which lie studied was concerned. How- 

 ever, these are the vei-y differences which dis- 

 tinguish aestiuirius from ealifo-rnieus. (xilbert 

 and Starks. by a comparison of the types of 

 m^igditlenae and aestuarius have already concluded 

 that the former was based on a specimen of the 

 latter. Notwithstanding that the edition of the 

 check list by Jordan, Evermann and Clark (1930) 

 lists magdalenae as a tenable species, this name 

 should be relegated to the synonymy of aestuarius. 



Economic importance. — Xo data are at present 

 extant as to the economic importance of this 

 flounder, if indeed, it enters the market at all. 

 However, the species seems to be common where 

 it does occur and it also reaches marketable size. 

 Consequently, it seems to offer possibilities for 

 exploitation, should it prove to occur in com- 

 mercial quantities. Moreover, in view of its close 

 resemblance to the California halibut, it is possible 

 that it now enters the market mixed with that 

 species in catches obtained southward, in Mexican 

 waters. 



Paralichthys aestuarius Gilbert and Scofield, Proc. IT. S. 

 Nat. Mus. 20 : 49i», pi. 39, 1898 (Shoal Point, mouth of 

 Colorado Kiver, Mexico). — Johdax :iih1 Kvermaxx. Bull. 

 U. S. Nat. Mus. 47 (3) : 2026, 1898 (Shoal Point, Mouth of 

 Colorado River, Mexico). 



Paralichthiis magdnlcnae Abbott, ibid., p. 2871 (Mag- 

 dalena Bay, Lower California). 



Paralichthys aestmirius Gilbert and Starks, Mem. 

 California Acad. Sci. 4: 198, 1904 (type comiwred with 

 maijdalcnae) . 



Paralichthys magdalenae Jordan and others. Kept, U. S. 

 Comm. Fish., 1928: 223. 1030 (listed). 



Paralichthys aestuarius Joedan and others, ibid., 224 

 (listed). — Norman. Monogr. Flatfishes, p. S2, fig. 48, 1934 

 (based on a paratype). — Bredee*.Bu11. Bingham Ocean. 

 Coll. 2 (3) : 193G ( San Franeisquito Bay, Gongago Bay, 

 Conception Bay, San Felipe Bay, Angeles Bay. all locali- 

 ties in Gulf of California ) . — Hiyama, Marine Fishes of the 

 Pacific Coast of Mexico. Edited by T. Kumuda, p. 58, pi. 

 91, 1937 (Mexico). 



•The majority of sperimens forming the bnsis of the present 

 account are the same as those forming the basis of this record, 

 and I wish to expn^B.'s my gratitude to Ur. Breder for the 

 opportunity of sludyint; these specimens. 



