The Synonymy of the Viviparous Polychaete Meant hes lighti 
Hartman (1938) with Nereis limnicola Johnson (1903) 
Ralph L Smith^ 
Nereis limnicola was described by Johnson 
(1903) from the fresh- water Lake Merced in 
San Francisco, California. Since that time no 
reports of its occurrence have been published. 
Hartman (1938) noted that the boundaries 
and bed of the lake have been "altered by 
dredging and roadbuilding operations, and 
that what was once the type locality of Nereis 
limnicola now lies many feet below a road 
bed." In 1938 Hartman described Neanthes 
lighti from small estuaries on the coast of 
Marin and Sonoma counties to the north of 
San Francisco, and from pools described as 
fresh along the Russian River. In this paper 
Hartman mentions N. limnicola, but does not 
discuss the possibility of the two forms being 
synonymous. Later she has stated (Light et al., 
1954: 88) that N. lighti "may prove to be 
Nereis limnicola . . . .” In 1941, N. lighti was 
found to be viviparous by Dr. Marian Petti- 
bone (reported by Hartman, 1944: 252), and 
an account of its embryology has been given 
by Smith (1950). Since viviparity and the 
ability to live in fresh water are rare among 
polychaetes, and since N. lighti seems to offer 
excellent experimental material, it is impor- 
tant that its identity be clearly established. 
In recent years, reports of the existence of 
fresh-water nereids in Lake Merced have 
reached us, and search revealed them. A 
viviparous nereid answering the descriptions 
of N. limnicola and N. lighti has been found 
in abundance in a sandy beach on the north- 
ern shore of the northern part of what was 
originally the single lake. The type locality 
^ Department of Zoology, University of California, 
Berkeley. Manuscript received July 28, 1958. 
described by Johnson ("the outlet of a 
'slough’ on the eastern shore of the southern 
arm of the lake’’) has indeed been filled for 
a roadbed, as Hartman stated, and yielded no 
specimens, although further search at lower 
water levels may reveal them; the present 
substrate is not especially favorable. 
The finding of this material makes possible 
a comparison of N. limnicola and N. lighti. 
Johnson’s description (1903) fits both species 
well, except that he did not notice viviparity 
in N. limnicola. Hartman’s description (1938) 
also fits both, except that she did not observe 
in N. lighti a feature remarked upon by 
Johnson (1903: 210), namely, the presence in 
posterior neuropodia of a "stout, falcate type 
of setae ... in which the appendage is firmly 
anchylosed to the shaft, the whole forming 
one continuous piece.’’ As for the first dis- 
crepancy, it is clear that the Lake Merced 
population is viviparous, precisely in the fash- 
ion described in the Salinas River population 
of N. lightihy Smith (1950), and subsequently 
observed in populations from other localities 
along the coast as far north as the Canadian 
border. As for the second discrepancy, in 
1951 the writer examined, in the U. S. Na- 
tional Museum, two specimens of N. limni- 
cola, Cat. no. 5166, collected in Lake Merced 
on Oct. 29, 1895, by H. P. Johnson, and 
labeled as "type specimens.’’ At that time I 
also inspected the type lot of Neanthes lighti 
Hartman, USNM Cat. no. 20537. The fused 
setae as described by Johnson are present in 
both groups of specimens, as they are in all 
N. lighti of the writer’s collections, and the 
parapodia of both lots answer Johnson’s de- 
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