IIMYC   23581
INSTITUTO DE INVESTIGACIONES MARINAS Y COSTERAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Pyrostephos vanhoeffeni (Cnidaria, Siphonophora): New data on zooid development and an updated review on its distribution.
Autor/es:
ARAUJO E.; GUERRERO E.; LINDSAY; GROSSMAN; CANEPA; GONZALEZ; GENZANO; MIANZAN; FUENTES
Lugar:
Barcelona
Reunión:
Congreso; XI SCAR (Scientific Committee on Antarctic Research) International Biology Symposium; 2013
Resumen:
The order
Siphonophora, free-swimming colonial pelagic hydrozoans (Cnidaria), has the
greatest degree of polymorphism and functional specialization and the most
complex organization of all colonial animals. For those reasons and their
fragility, they are very difficult to study, and many of described earlier
species require a complement or expansion of their taxonomic features. Pyrostephos vanhoeffeni Moser, 1925 is a
Physonectae siphonophore with a very complex morphology, especially in their
nectophores. This species has been considered to be endemic to the Antarctic
and Subantarctic waters until recent studies and it is one of the very few
Physonectid species well adapted to cold waters. We recorded P. vanhoeffeni in the continental shelf
of Argentina up to 39º S; the most northern occurrence in Atlantic waters so
far. A total of 599 colonies were found in 71 zooplankton samples collected
between 1996 and 2008. Although the colonial structure was damaged during
sampling and fixation, we were able to recognize that they were mainly young
colonies composed of many young nectophores and an active nectosome budding
zone. The main objective of this work is to describe the different P. vanhoeffeni?s nectophores development
stages. As well as to make an updated review of its geographical distribution
based in all published records that we afterwards related it to environmental
and oceanographic features in order to have a better understanding of this
species biogeography. Moreover, as it was the only siphonophora species present
in many of the samples, the presence of post-larval stages allowed us to
definitively assign the form previously known as Mica micula Margulis, 1982 to P.
vanhoeffeni. These new taxonomic descriptions plus the information about
the expansion of its geographical distribution will be of great importance in
future studies.