Brooding comatulids from the southwestern Atlantic, Argentina (Echinodermata: Crinoidea)

Isometra vivipara and Phrixometra nutrix are two brooding feather stars (order Comatulida) that are widely distributed along the southern tip of South America to the Antarctic. We examined 210 specimens of I. vivipara and 38 specimens of P.nutrix collected during five cruises in the southwestern Atlantic between 91 and 642 m depth. Specimens were analyzed and deposited in the National Invertebrate collection, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”. Isometravivipara reaches an arm length of 49 mm long and shows two stages of brooding: in the female genital pinnules and on the cirri of the mother. In this paper, we propose that spermatozoa reach the ovary via the ambulacral groove. By contrast, P. nutrix is smaller with a maximum recorded size of 26.8 mm, and brooding occurs only inside the female genital pinnules. Here, we record, for the first time for P.nutrix, spermatozoa shape and a cleaved egg attached externally to a genital pinnule of a female. The distributions of both species and their abundances in some areas could be related to their doliolaria larval stage. In addition, we extend the bathymetric range of P.nutrix to 512 m in Marine Protected Area Namuncurá/Burdwood Bank and distribution to the Mar del Plata Submarine Canyon area. We also propose mode of reproduction and developmental patterns as attributes for identification and possible explanations for their differences in distribution.Fil: Pertossi, Renata Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Penchazadeh, Pablo E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Universidad Simón Bolívar; VenezuelaFil: Martinez, Mariano Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Growing up in the deep-sea protected development in deep-sea invertebrates: A case study in the southwestern Atlantic Ocean

Marine invertebrates display a range of reproductive strategies, from external fertilization to several methods to protect the young. Both brooding or protected development of benthic species and direct development species (when juveniles born in a smaller version of its adult form) involves reducing the time that the larvae and/or juveniles spend in the plankton. The different forms of juvenile protection are often associated with the taxonomic group, although certain groups are much diversified in terms of their reproductive modes. However, the area where the species live also seems to play a key role. Several authors have indicated the unusual proportion of brooding species in the Southern Ocean, in particular in the southwestern Atlantic, including its adjacent deep-sea. The knowledge about the reproductive characteristics of most of the fauna in this area remains unknown. Proof of this are the great number of studies carried out in recent years, describing the reproductive features of several species (many also new), with some of them having many peculiarities about their biology.Fil: Teso, Silvia Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Martinez, Mariano Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Lauretta, Daniel Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Pastorino, Roberto Santiago Guido. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Urteaga, Diego Gaston. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Brogger, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Arrighetti, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Rivadeneira, Pamela Ruth. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Flores, Jonathan Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Pertossi, Renata Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Sánchez, Noelia Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Pacheco, Leonel Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Di Luca, Javier Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Sanchez Antelo, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Risaro, Jessica Ayelen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Ciocco, Rocio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Penchaszadeh, Pablo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Reproductive biology of the brooding feather star Phrixometra nutrix, from the southwestern Atlantic

Reproduction of the brooding feather star Phrixometra nutrix was studied from the deep southwestern Atlantic Ocean. Samples were collected using dredge trawlers and fishing nets on board the B/O Puerto Deseado, between 91 and 512 m depth. Reproductive biology was studied using modern optical techniques including histology and scanning electron microscopy. Here we present the first record of genital papillae for class Crinoidea. Genital papillae have been reported in all extant echinoderm classes except for Crinoidea. In addition, a high proportion (16%) of hermaphroditic specimens was found in the analyzed samples. Finally, cystidean and pentacrinoid stages were found inside the marsupium of Phrixometra nutrix. It is expected that this work will enable further discoveries of crinoid reproductive biology considering the ecological and phylogenetic importance of brooding crinoids.Fil: Pertossi, Renata Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Martinez, Mariano Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Reproduction and developmental stages in the crinoid Isometra vivipara Mortensen, 1917 from the southwestern Atlantic

Isometra vivipara Mortensen, 1917, which was described one hundred years ago, represents a particular case within the feather stars of the southwestern Atlantic Ocean. This is a dioecious species in which the oocytes are fertilized in the ovary and not externally as in other species. Some authors have pointed out that I. vivipara stores spermatozoa in the genital pinnules of the female, although there is still no detailed data on how they reach the pinnule. Besides, this species is characterized by possessing a second sexually dimorphic trait and presents two incubation stages: one in the genital pinnules, and the second one attached in the cirri of the mother. In the present work, the reproduction and developmental stages of the I. vivipara were studied. Samples were taken from two cruises aboard the B/O “Puerto Deseado” to Burdwood Bank/MPA Namuncurá at 84–642 m depth, during March/April 2016 and April/May 2017. Four developmental stages were recognized: Embryo, Doliolaria larvae (inside the brood pouches), Cystidean, and Pentacrinoids (attached in the cirri of the mother). In addition, histological analysis showed that fertilization in I. vivipara could occur between the ovary and the marsupium. The egg measurements reached 0.35 mm in diameter—on of the largest egg size within South America and Antarctica comatulids—whereas for the larvae the largest registered diameter was 0.77 mm. These results are compared and discussed with all the available information of comatulids from South America and Antarctica.Fil: Pertossi, Renata Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Brogger, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Penchaszadeh, Pablo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Martinez, Mariano Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin