Hydrobiologia 298: 245-252, 1995.
D. Belk, H. J. Dumont & G. Maier (eds), Studies on Large Branchiopod Biology and Aquaculture II.
© 1995 Kluwer Academic Publishers.
245
Age-influenced morphological changes in Leptestheria saetosa Marincek et
Petrov, 1992 (Conchostraca, Crustacea)
Brigita Petro v & Magdalena Marincek
Institute of Zoo logy, Faculty of Biology, Universuty of Belgrade, Studentski trg 16, 11 000 Belgrade, Yugoslavia
Key words: Conchostraca, Leptestheria, morphology, ageing
Abstract
Morphological changes during the process of ageing of Leptestheria saetosa Marincek et Petro v, 1992 were
observed. It was established that the greatest number of analysed characteristics change intensively after sexual
maturation. These changes continue throughout the entire life, although they are very slow in old specimens. Such a
large number of changes brings about considerable morphological differences between adult specimens of different
age.
Introduction
Insufficient knowledge of morphological changes taking place during the postlarval period causes considerable difficulties in the taxonomy of Conchostraca.
New species were sometimes described on the basis of
discovery of different immature stages, e.g. within the
genus Cyzicus Audoin, 1873 (Botnariuc, 1947).
While there exist some rare and incomplete data
on the peculiarities of the first biconchal stage of some
species (Botnariuc, 1947, 1948; Kapler, 1960; Anderson, 1967; Strenth & Sissom, 1975; BratCik, 1980;
Monakov et al., 1980) there are almost no data on
changes during the postlarval period. Kapler (1960)
was the only one to observe the development of a conchostracan species (namely Leptestheria dahalacensis
Ruppel, 1835) up to sexual maturity, but these observations were incomplete; they included only a few
taxonomically unimportant characteristics.
The only data on changes occurring in young specimens during sexual maturation are those given by
Botnariuc (1947). However, he deals only with differentiation of the first two pairs of appendages and
with changes in the appearance of the head in males
of Leptestheria dahalacensis and Cyzicus tetracerus
(Krynicky, 1830).
Material and methods
Specimens of different ages of the species Leptestheria
saetosa, recently discovered in Yugoslavia (Marincek
& Petrov, 1992) were used for this investigation. Specimens were taken from the type locality or they were
cultivated in the laboratory. In order to establish laboratory cultures, mud from an ephemeral pond containing
diapausing eggs, was used.
During this investigation maximal length and
width, and length/width ratio of the shell, presence
and distribution of setae on the shell, appearance of
the head including shape of the rostrum and of the
occipital region were observed. In order to establish
the exact length of the occipital region, an occipital
index was calculated according to Botnariuc (1947).
The number of papilae and segments; the structure of
sensory organs on the first pair of antennae; the number
of segments on proto-, endo- and exopod; the number,
structure and distribution of spines and setae on the
second pair of antennae; the total number of trunk segments and number of segments equipped with spines;
and the number and distribution of spines on each trunk
segment, as well as their structure were analysed. On
the telson, the number and structure of spines on the
dorsal ridge and on the claws were examined. In addition, the number of appendages and the entire structure
of the first, second and third pair in males, and of the
D. Belk, H. J. Dumont & G. Maier (eds), Studies on Large Branchiopod Biology and Aquaculture II.
© 1995 Kluwer Academic Publishers.
245
Age-influenced morphological changes in Leptestheria saetosa Marincek et
Petrov, 1992 (Conchostraca, Crustacea)
Brigita Petro v & Magdalena Marincek
Institute of Zoo logy, Faculty of Biology, Universuty of Belgrade, Studentski trg 16, 11 000 Belgrade, Yugoslavia
Key words: Conchostraca, Leptestheria, morphology, ageing
Abstract
Morphological changes during the process of ageing of Leptestheria saetosa Marincek et Petro v, 1992 were
observed. It was established that the greatest number of analysed characteristics change intensively after sexual
maturation. These changes continue throughout the entire life, although they are very slow in old specimens. Such a
large number of changes brings about considerable morphological differences between adult specimens of different
age.
Introduction
Insufficient knowledge of morphological changes taking place during the postlarval period causes considerable difficulties in the taxonomy of Conchostraca.
New species were sometimes described on the basis of
discovery of different immature stages, e.g. within the
genus Cyzicus Audoin, 1873 (Botnariuc, 1947).
While there exist some rare and incomplete data
on the peculiarities of the first biconchal stage of some
species (Botnariuc, 1947, 1948; Kapler, 1960; Anderson, 1967; Strenth & Sissom, 1975; BratCik, 1980;
Monakov et al., 1980) there are almost no data on
changes during the postlarval period. Kapler (1960)
was the only one to observe the development of a conchostracan species (namely Leptestheria dahalacensis
Ruppel, 1835) up to sexual maturity, but these observations were incomplete; they included only a few
taxonomically unimportant characteristics.
The only data on changes occurring in young specimens during sexual maturation are those given by
Botnariuc (1947). However, he deals only with differentiation of the first two pairs of appendages and
with changes in the appearance of the head in males
of Leptestheria dahalacensis and Cyzicus tetracerus
(Krynicky, 1830).
Material and methods
Specimens of different ages of the species Leptestheria
saetosa, recently discovered in Yugoslavia (Marincek
& Petrov, 1992) were used for this investigation. Specimens were taken from the type locality or they were
cultivated in the laboratory. In order to establish laboratory cultures, mud from an ephemeral pond containing
diapausing eggs, was used.
During this investigation maximal length and
width, and length/width ratio of the shell, presence
and distribution of setae on the shell, appearance of
the head including shape of the rostrum and of the
occipital region were observed. In order to establish
the exact length of the occipital region, an occipital
index was calculated according to Botnariuc (1947).
The number of papilae and segments; the structure of
sensory organs on the first pair of antennae; the number
of segments on proto-, endo- and exopod; the number,
structure and distribution of spines and setae on the
second pair of antennae; the total number of trunk segments and number of segments equipped with spines;
and the number and distribution of spines on each trunk
segment, as well as their structure were analysed. On
the telson, the number and structure of spines on the
dorsal ridge and on the claws were examined. In addition, the number of appendages and the entire structure
of the first, second and third pair in males, and of the