50
Table 1 cont.. Sex ratio estimates for natural populations of clam shrimps. Sample types are: adults from
field collections (field) and laboratory-reared adults from sediment samples (lab.). Numbers in brackets
refer to original data tabulated in Appendix 1.
Taxon
Sample
size
Eulimnadia gunturensis
47
Radhakrishna & Durga Prasad
Eulimnadia ovilunata Martin & Belk
79
Eulimnadia ovisimilis Martin & Belk
52
Eulimnadia texana Packard
>1400
Eulimnadia sp.
228
lmnadia panonica Marincek & Petrov
20
lmnadia yeyetta Hertzog
32
lmnadia voitestii Botnariuc &
31
Orghidan
1941
Limnadia lenticularis (L.)
>2000
Limnadia stanleyana King
Limnadia urukhai Webb & Bell
Limnadiopsium tatei (Spencer & Hall)
Limnadopsis birchii Spencer & Hall
Metalimnadia serratura Mattox
in Texas (Sissom, 1980) and Colombia (Roessler &
Sanchez, 1986; Roessler, 1995c); and Botnariuc &
Vifia Bayes (1977) have inferred their presence in Cuba
based on apparent clasper damage on the carapaces
of females. In addition, Paracyclestheria sinensis has
been described from a small collection of females in
China (Shen & Dai, 1987).
Mathias (1937) noted two curious patterns in Limnadiinae wherein (1) some species of Australian Limnadia were apparently bisexual whereas species elsewhere lacked males altogether, and (2) males were
absent or rare in all species of Eulimnadia. Since his
review, more examples of this dichotomy in Limnadia have been discovered, as have many more species
of Eulimnadia showing female-bias or complete male
absence. Of particular interest is the discovery of rare
males in one population of Limnadia lenticularis (see
Table A, appendix 1), a species in which previous collections over the last century and a half (and totaling
?
58
8
6
21
%
Sample
References
male
type
15
field
Radhakrishna & Durga
Prasad, 1976
4
field
Martin & Belk, 1989
6
field
Martin & Belk, 1989
0-42
lab
Sassaman, 1989;
Sassaman & Weeks, 1993;
Knoll, 1994
0
field
Stern & Stern, 1971;c.,
Belk,1989
50
field
Marincek & Petrov, 1984
56
field
Hertzog, 1935
48
field
Botnariuc & Orghidan,
0-2
field
Lereboullet, 1866; Sars,
1896a; Zaffagnini, 1969;
Cottarelli & Mura, 1983;
(13)
R::l50
field
Sars, 1895
47
field
Webb & Bell, 1979
88
field
Spencer & Hall, 1896
50
field
Spencer & Hall, 1896
48
field
Mattox, 1952; Roessler,
1994, a,b
thousands to tens of thousands of individuals) have not
contained any males.
Reproductive correlates of sex ratio
To what extent are data on population sex ratios relevant to an understanding of reproductive modes in
conchostracans? Over the last few years, I have conducted a number of laboratory experiments on various
species of clam shrimps that establish the correlation
between population sex ratios and intrinsic reproductive modes.
Virtually all species of Cyzicidae, Leptestheridae
and Lynceidae are characterized by sex ratios near
unity, thus suggesting obligate sexuality. The primary experimental evidence for obligate sexuality is the
comparison of reproductive success of females reared
in isolation with those that are mated. I have reared
20 females of Eocyzicus concavus from hatching to
Table 1 cont.. Sex ratio estimates for natural populations of clam shrimps. Sample types are: adults from
field collections (field) and laboratory-reared adults from sediment samples (lab.). Numbers in brackets
refer to original data tabulated in Appendix 1.
Taxon
Sample
size
Eulimnadia gunturensis
47
Radhakrishna & Durga Prasad
Eulimnadia ovilunata Martin & Belk
79
Eulimnadia ovisimilis Martin & Belk
52
Eulimnadia texana Packard
>1400
Eulimnadia sp.
228
lmnadia panonica Marincek & Petrov
20
lmnadia yeyetta Hertzog
32
lmnadia voitestii Botnariuc &
31
Orghidan
1941
Limnadia lenticularis (L.)
>2000
Limnadia stanleyana King
Limnadia urukhai Webb & Bell
Limnadiopsium tatei (Spencer & Hall)
Limnadopsis birchii Spencer & Hall
Metalimnadia serratura Mattox
in Texas (Sissom, 1980) and Colombia (Roessler &
Sanchez, 1986; Roessler, 1995c); and Botnariuc &
Vifia Bayes (1977) have inferred their presence in Cuba
based on apparent clasper damage on the carapaces
of females. In addition, Paracyclestheria sinensis has
been described from a small collection of females in
China (Shen & Dai, 1987).
Mathias (1937) noted two curious patterns in Limnadiinae wherein (1) some species of Australian Limnadia were apparently bisexual whereas species elsewhere lacked males altogether, and (2) males were
absent or rare in all species of Eulimnadia. Since his
review, more examples of this dichotomy in Limnadia have been discovered, as have many more species
of Eulimnadia showing female-bias or complete male
absence. Of particular interest is the discovery of rare
males in one population of Limnadia lenticularis (see
Table A, appendix 1), a species in which previous collections over the last century and a half (and totaling
?
58
8
6
21
%
Sample
References
male
type
15
field
Radhakrishna & Durga
Prasad, 1976
4
field
Martin & Belk, 1989
6
field
Martin & Belk, 1989
0-42
lab
Sassaman, 1989;
Sassaman & Weeks, 1993;
Knoll, 1994
0
field
Stern & Stern, 1971;c.,
Belk,1989
50
field
Marincek & Petrov, 1984
56
field
Hertzog, 1935
48
field
Botnariuc & Orghidan,
0-2
field
Lereboullet, 1866; Sars,
1896a; Zaffagnini, 1969;
Cottarelli & Mura, 1983;
(13)
R::l50
field
Sars, 1895
47
field
Webb & Bell, 1979
88
field
Spencer & Hall, 1896
50
field
Spencer & Hall, 1896
48
field
Mattox, 1952; Roessler,
1994, a,b
thousands to tens of thousands of individuals) have not
contained any males.
Reproductive correlates of sex ratio
To what extent are data on population sex ratios relevant to an understanding of reproductive modes in
conchostracans? Over the last few years, I have conducted a number of laboratory experiments on various
species of clam shrimps that establish the correlation
between population sex ratios and intrinsic reproductive modes.
Virtually all species of Cyzicidae, Leptestheridae
and Lynceidae are characterized by sex ratios near
unity, thus suggesting obligate sexuality. The primary experimental evidence for obligate sexuality is the
comparison of reproductive success of females reared
in isolation with those that are mated. I have reared
20 females of Eocyzicus concavus from hatching to