Hydrobiologia 298: 113-124, 1995.
D. Belk, H. 1. Dumont & G. Maier (eds), Studies on Large Branchiopod Biology and Aquaculture I!.
© 1995 Kluwer Academic Publishers.
113
Review of Colombian Conchostraca (Crustacea) - ecological aspects and life
cycles - family Cyclestheriidae
Ewald W. Roessler
Departamento de Ciencias Biol6gicas, Universidad de los Andes, A.A. 4976, Bogota, Colombia, South America
Key words: conchostraca, Colombia, Cyclestheria, ecology, life cycle, reproduction
Abstract
This study gives an overview and describes special aspects of the biology, ecology and the life cycle of Cyclestheria
hislopi (Baird, 1859). This species is most commonly found in parthenogenic ally reproducing populations which
produce large, directly developing nondiapause eggs. But periodically and under certain environmental conditions,
sexually reproducing generations appear and produce diapause eggs. The sexual generations include males and
particularly constituted females, which undergo a complete transformation into a special type of ephippium.
Cyclestheria is the only known conchostracan species which does not occur in the initial phases of temporary water
bodies, but develops in older temporary pools and even in permanent waters. It survives in the presence of effective
depredators like fish by hiding within a special self-made mucus capsule.
Introdnction
As with euphyllopods in general, conchostracans'
active life phases are typically restricted to temporary
waters or water bodies with extreme environmental
conditions. A remarkable exception to this rule is the
family Cyclestheriidae containing the single species,
Cyclestheria hislopi (Baird, 1859), which has been
reported from all continents except Antarctica and can
be considered a species of circumtropical distribution;
Baird (1850), Barnard (1929), Dodds (1926), Egborge
et al. (1989), Nair (1968), Nayar & Nair (1968),
Roessler & Sanchez (1986), Sissom (1975, 1980), Halloy (1981), Stuhlmann (1888), and Sars (1887).
Conchostracans that appear in the temporary ponds
at the very beginning of community development
attempt to survive pressures of enemies by high reproduction rates. This survival mode is commonly known
as the r-strategy and is generally characteristic of pioneer communities. Indeed, euphyllopods generally fit
well into this category.
The exception is Cyclestheria which, in contrast
to other conchostracans, is not part of the very initial
phases of ecological successions in freshwater bodies;
so it can be expected that its survival strategies are
quite different and particular. Cyclestheria is apparently the only recent conchostracan species which
responds to enemy pressure with active defense mechanisms, known as k-strategies, rather than by evasion,
restriction to particular environments and attempts to
increase the number of offspring.
The purpose of this paper is to present some aspects
of the biology and life cycle of Cyclestheria hislopi
(Baird, 1859) as found in Colombia. An earlier version was previously published in Spanish (Roessler &
Sanchez, 1986).
Materials and methods
The studies were carried out during the past 15 years
in the tropical lowlands of Colombia. Specimens were
collected with dip nets with mesh widths varying
according to the development stages wanted and were
fixed in 4%-8% formalin or 90% ethyl alcohol. For
histological studies special fixatives were used, primarily Bouin's solution. Permanent mountings of certain specimens and of histological sections were made
by inclusions in artificial balsam.
D. Belk, H. 1. Dumont & G. Maier (eds), Studies on Large Branchiopod Biology and Aquaculture I!.
© 1995 Kluwer Academic Publishers.
113
Review of Colombian Conchostraca (Crustacea) - ecological aspects and life
cycles - family Cyclestheriidae
Ewald W. Roessler
Departamento de Ciencias Biol6gicas, Universidad de los Andes, A.A. 4976, Bogota, Colombia, South America
Key words: conchostraca, Colombia, Cyclestheria, ecology, life cycle, reproduction
Abstract
This study gives an overview and describes special aspects of the biology, ecology and the life cycle of Cyclestheria
hislopi (Baird, 1859). This species is most commonly found in parthenogenic ally reproducing populations which
produce large, directly developing nondiapause eggs. But periodically and under certain environmental conditions,
sexually reproducing generations appear and produce diapause eggs. The sexual generations include males and
particularly constituted females, which undergo a complete transformation into a special type of ephippium.
Cyclestheria is the only known conchostracan species which does not occur in the initial phases of temporary water
bodies, but develops in older temporary pools and even in permanent waters. It survives in the presence of effective
depredators like fish by hiding within a special self-made mucus capsule.
Introdnction
As with euphyllopods in general, conchostracans'
active life phases are typically restricted to temporary
waters or water bodies with extreme environmental
conditions. A remarkable exception to this rule is the
family Cyclestheriidae containing the single species,
Cyclestheria hislopi (Baird, 1859), which has been
reported from all continents except Antarctica and can
be considered a species of circumtropical distribution;
Baird (1850), Barnard (1929), Dodds (1926), Egborge
et al. (1989), Nair (1968), Nayar & Nair (1968),
Roessler & Sanchez (1986), Sissom (1975, 1980), Halloy (1981), Stuhlmann (1888), and Sars (1887).
Conchostracans that appear in the temporary ponds
at the very beginning of community development
attempt to survive pressures of enemies by high reproduction rates. This survival mode is commonly known
as the r-strategy and is generally characteristic of pioneer communities. Indeed, euphyllopods generally fit
well into this category.
The exception is Cyclestheria which, in contrast
to other conchostracans, is not part of the very initial
phases of ecological successions in freshwater bodies;
so it can be expected that its survival strategies are
quite different and particular. Cyclestheria is apparently the only recent conchostracan species which
responds to enemy pressure with active defense mechanisms, known as k-strategies, rather than by evasion,
restriction to particular environments and attempts to
increase the number of offspring.
The purpose of this paper is to present some aspects
of the biology and life cycle of Cyclestheria hislopi
(Baird, 1859) as found in Colombia. An earlier version was previously published in Spanish (Roessler &
Sanchez, 1986).
Materials and methods
The studies were carried out during the past 15 years
in the tropical lowlands of Colombia. Specimens were
collected with dip nets with mesh widths varying
according to the development stages wanted and were
fixed in 4%-8% formalin or 90% ethyl alcohol. For
histological studies special fixatives were used, primarily Bouin's solution. Permanent mountings of certain specimens and of histological sections were made
by inclusions in artificial balsam.