204
the members of the genus. Later, Linder (1941:233)
indicated that the frontal appendage is a constant character in all species known at that time. He rejected the
subgenus Streptocephalellus, together with the other
two subgenera advancing the argument that there was
no clear distinction between them (Linder, 1941:233).
Recently, Brendonck et al. (1992) grouped S. lamellifer, S. sudanicus Daday, S. kaokoensis Barnard, and
S. zuluensis Brendonck & Hamer in a new subgenus
Parastreptocephalus Brendonck, Hamer & Thiery. Its
main diagnostic characteristics are spinules on the dorsal side of the finger, and tetrahedral cysts. Hamer &
Appleton (1993) mentioned that the southern African
species can be divided into nine species groups "based
on similarities in antennal and frontal appendage morphology", and Hamer & Brendonck (1993) noted that
all African species fall into ten species groups based
on the above characters. Later, Hamer et at. (1994 a,b)
classified the African species into ten species groups
based on male antennal characters, such as the shape of
the finger and thumb, the presence and shape of teeth
on these structures, presence or absence and shape of
the spur and the number of teeth separating it from the
anterior thumb region, and the presence and shape of
processes on the peduncle of the distal antennal outgrowth. They concluded that not all groupings were
clear-cut as some species share characters with other
species groups, and that further research on additional characters and the aplication of genetic methods
are necessary before a final division of the genus can
be attempted (Hamer et aI., 1994 a,b). Brendonck &
Coomans (1994 a,b) found thatthere is little correlation
between the species groups based on cysts morphology
and those proposed by Hamer et ai. (1994 a,b).
While developing a data base for phy logenetic analysis of the 13 New World streptocephalids (MaedaMartInez et ai., 1995; this volume), we compared
them with species from Africa, Europe, and India. In
doing this, we found that the morphology of the peduncle of the distal outgrowth, and the biramous ovaries
developed in seven North American species can contribute to the systematics of the genus. The peduncle
of the distal outgrowth was never considered in any of
the previous systems of classification. Similarly, the
gross morphology of the ovaries has been neglected,
not only within the Streptocephalidae, but within the
entire order Anostraca. Starting from these findings,
our investigation consisted of (1) a review ofthe external morphology of the male antenna, (2) biometry of
selected parts of the male antenna to obtain informative
ratios, (3) a review of the presence or absence of the
pulvinus, linguiform genital outgrowths, extension of
the non-retractile basal parts of the penes, and general
morphology of the cercopods, (4) a study of the location of the ovaries and the extension of the brood pouch,
and 5) elaboration of a classification of the species. The
study was carried out by comparison of 49 species of
Streptocephalus (including 4 undescribed species, 1
from Africa and 3 from North America). On the basis
of three ratios, the species were divided in three general
groups, i.e. species with (1) short, (2) intermediate and
(3) long antennal peduncles. After this, the morphological similarity of the antennal hand, frontal appendage,
and ovaries was used to sort the species of each peduncle size class into apparent species groups. This sorting resulted in nine species groups, and five subgroups
within two of the species groups. On the basis of this
classification procedure, the pulvinus, linguiform genital outgrowths, and cercopods were evaluated as being
of secondary importance for use in systematics studies
above the species level of the Streptocephalidae.
Material and methods
The material came from collections deposited at several institutions, and from four private collections,
namely: British Museum of Natural History (BMNH),
Museo de Zoologia, Escuela Nacional de Estudios Profesionales, Iztacala, UNAM, Mexico (ENEP), Hornonitrianske Muzeum Prievidza, Slovakia (HMPS), Hungarian Natural History Museum (HNHM), Koninklijk
Belgisch Instituut voor Natuurwetenschappen, Brussels, Belgium (KBIN), Natural History Museum of Los
Angeles County, California, USA (LACM), Museum
National d'Histoire Naturelle, France (MNHN), South
African Museum, Cape Town (SAM), Laboratory of
Animal Ecology, University of Ghent, Belgium (UG),
Escuela Superior de Biologia, Universidad Juarez del
Estado de Durango, Mexico (UJED), National Museum of Natural History, Smithsonian Institution, USA
(USNM), and private collections of Dr D. Belk (DB),
Dr G. Murugan (GM), Dr L. Brendonck (LB), and
Michelle Hamer (MH).
The description of the antenna is based on our
observations on adults, and specimens in different postembryonic stages of S. dichotomus, S. proboscideus (Frauenfeld), and S. torvicornis, all of them
cultured in the Laboratory of Animal Ecology, University of Ghent, Belgium, and on the postembryonic
development of S. torvicornis and S. sealii as described
by Claus (1886) and Baqai (1963). The postembry-
the members of the genus. Later, Linder (1941:233)
indicated that the frontal appendage is a constant character in all species known at that time. He rejected the
subgenus Streptocephalellus, together with the other
two subgenera advancing the argument that there was
no clear distinction between them (Linder, 1941:233).
Recently, Brendonck et al. (1992) grouped S. lamellifer, S. sudanicus Daday, S. kaokoensis Barnard, and
S. zuluensis Brendonck & Hamer in a new subgenus
Parastreptocephalus Brendonck, Hamer & Thiery. Its
main diagnostic characteristics are spinules on the dorsal side of the finger, and tetrahedral cysts. Hamer &
Appleton (1993) mentioned that the southern African
species can be divided into nine species groups "based
on similarities in antennal and frontal appendage morphology", and Hamer & Brendonck (1993) noted that
all African species fall into ten species groups based
on the above characters. Later, Hamer et at. (1994 a,b)
classified the African species into ten species groups
based on male antennal characters, such as the shape of
the finger and thumb, the presence and shape of teeth
on these structures, presence or absence and shape of
the spur and the number of teeth separating it from the
anterior thumb region, and the presence and shape of
processes on the peduncle of the distal antennal outgrowth. They concluded that not all groupings were
clear-cut as some species share characters with other
species groups, and that further research on additional characters and the aplication of genetic methods
are necessary before a final division of the genus can
be attempted (Hamer et aI., 1994 a,b). Brendonck &
Coomans (1994 a,b) found thatthere is little correlation
between the species groups based on cysts morphology
and those proposed by Hamer et ai. (1994 a,b).
While developing a data base for phy logenetic analysis of the 13 New World streptocephalids (MaedaMartInez et ai., 1995; this volume), we compared
them with species from Africa, Europe, and India. In
doing this, we found that the morphology of the peduncle of the distal outgrowth, and the biramous ovaries
developed in seven North American species can contribute to the systematics of the genus. The peduncle
of the distal outgrowth was never considered in any of
the previous systems of classification. Similarly, the
gross morphology of the ovaries has been neglected,
not only within the Streptocephalidae, but within the
entire order Anostraca. Starting from these findings,
our investigation consisted of (1) a review ofthe external morphology of the male antenna, (2) biometry of
selected parts of the male antenna to obtain informative
ratios, (3) a review of the presence or absence of the
pulvinus, linguiform genital outgrowths, extension of
the non-retractile basal parts of the penes, and general
morphology of the cercopods, (4) a study of the location of the ovaries and the extension of the brood pouch,
and 5) elaboration of a classification of the species. The
study was carried out by comparison of 49 species of
Streptocephalus (including 4 undescribed species, 1
from Africa and 3 from North America). On the basis
of three ratios, the species were divided in three general
groups, i.e. species with (1) short, (2) intermediate and
(3) long antennal peduncles. After this, the morphological similarity of the antennal hand, frontal appendage,
and ovaries was used to sort the species of each peduncle size class into apparent species groups. This sorting resulted in nine species groups, and five subgroups
within two of the species groups. On the basis of this
classification procedure, the pulvinus, linguiform genital outgrowths, and cercopods were evaluated as being
of secondary importance for use in systematics studies
above the species level of the Streptocephalidae.
Material and methods
The material came from collections deposited at several institutions, and from four private collections,
namely: British Museum of Natural History (BMNH),
Museo de Zoologia, Escuela Nacional de Estudios Profesionales, Iztacala, UNAM, Mexico (ENEP), Hornonitrianske Muzeum Prievidza, Slovakia (HMPS), Hungarian Natural History Museum (HNHM), Koninklijk
Belgisch Instituut voor Natuurwetenschappen, Brussels, Belgium (KBIN), Natural History Museum of Los
Angeles County, California, USA (LACM), Museum
National d'Histoire Naturelle, France (MNHN), South
African Museum, Cape Town (SAM), Laboratory of
Animal Ecology, University of Ghent, Belgium (UG),
Escuela Superior de Biologia, Universidad Juarez del
Estado de Durango, Mexico (UJED), National Museum of Natural History, Smithsonian Institution, USA
(USNM), and private collections of Dr D. Belk (DB),
Dr G. Murugan (GM), Dr L. Brendonck (LB), and
Michelle Hamer (MH).
The description of the antenna is based on our
observations on adults, and specimens in different postembryonic stages of S. dichotomus, S. proboscideus (Frauenfeld), and S. torvicornis, all of them
cultured in the Laboratory of Animal Ecology, University of Ghent, Belgium, and on the postembryonic
development of S. torvicornis and S. sealii as described
by Claus (1886) and Baqai (1963). The postembry-