JUVENILE AND SEX CHARACTERS OF EVORTHODUS LYRICUS 
(FAM. GOBIIDjE ) 1 
By Isaac Ginsburg, Assistant Aquatic Biologist, United States Bureau oj Fisheries 
& 
INTRODUCTION 
Two species of gobies, which have been recorded from the Gulf coast of the 
United States and Mexico and which have been placed in separate genera based on 
characters which were universally accepted by taxonomists as generic, have been 
found to represent the two sexes of one and the same species. These two species are 
Gohius lyricus Girard and Evorthodus breviceps Gill. The latter species has been 
described from Trinidad, but it also has been reported from the Gulf coast of Mexico 
by Jordan and Richardson. The author has found it to be quite common in Louisiana. 
The young, described from Chesapeake Bay, have been placed in still another genus. 
The female has been named three times, the male independently twice, and the 
young once. 
Full-grown specimens of these two supposedly distinct species are readily sepa- 
rable by the character of the teeth. In E. breviceps the teeth are minute, as seen 
superficially, their distal margins are notched, and they are placed side by side in a 
single row. In G. lyricus the teeth are considerably larger, their margins entire, 
they are rather widely spaced, and the lower jaw has a row of larger teeth, usually 
four to six in number, behind the outer row. A band of small teeth has also been 
described in the lower jaw of the latter species, but this is evidently due to an error 
of observation. What appears like a band of villiform teeth is really a band of 
papillae as has been determined by dissecting out the papilliferous mucous membrane, 
drying and examining it under a microscope. 
During the summer of 1930 while collecting on the coast of Louisiana, the 
author found these fishes fairly common on Grand Isle and adjacent small islands in 
Barantaria Bay. Their favorite haunts are small marshy ponds with muddy bottoms, 
which communicate with the inner larger bodies of water at high tide but are isolated 
at low tide when they have a depth of about 2 to 4 feet. The remarkable similarity 
in the appearance of the two nominal species was striking and considering also their 
constant association, the idea of their being the two sexes of one species came to mind; 
but in view of the difference in the character of the teeth and the opinions of previ- 
ous workers, this notion at first was dismissed as untenable. However, a minute 
examination of the teeth has shown that in many specimens of intermediate size both 
kinds of teeth occur. This led to an extensive study of the teeth of many individuals, 
the sex of which was determined by dissection. This study has shown that Gobius 
lyricus is the male and Evorthodus breviceps the female of the same species. 
i Approved for publication, Jan. 23, 1931. 
67308—31 
117 
