Embryonic and larval development of a Porcellanid crab (Decapoda-Anomura) Pachycheles chubutensis (Boshi, 1963) in Patagonia

GONZÁLEZ PISANI XIMENA; PASTOR-DE-WARD CATALINA T.

Grahantown

Congreso; 9th International Congress of Reproduction in Marine Invertebrates; 2001

Rhodes University

<!-- /* Font Definitions */ @font-face {font-family:"Arial Narrow"; panose-1:2 11 5 6 2 2 2 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:647 2048 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0pt; margin-bottom:.0001pt; mso-pagination:none; font-size:12.0pt; mso-bidi-font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US; layout-grid-mode:line;} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 72.0pt 72.0pt 72.0pt; mso-header-margin:72.0pt; mso-footer-margin:72.0pt; mso-paper-source:0;} div.Section1 {page:Section1; mso-endnote-numbering-style:arabic;} --> The objective of this work is to present the results of the preliminary studies on embryonic and larval stages of Pachycheles chubutensis (Boschi, 1963). This crab can be found on Atlantic West coasts of South America from Cabo Polonio (Uruguay) to Rawson (Chubut, Argentina).   Ovigerous females of Pachycheles chubutensis were collected, once a month, during last spring and summer season (September to March, 2000-2001) from eulittoral zone on rock ledges. Specimens  were transported to the Centro Nacional Patagónico (CONICET) in Puerto Madryn. Females with advanced embryonic egg stage were maintained alive in the lab in a temperate constant room (16 ± 1 ºC), in aerated 1000 ml aquaria with sea water (34 %o) from the sampling until the larvae hatched. Recently hatched larvae from one female were placed in other 1000 ml aerated aquaria with 0,45 mm filtered sea water (34 %o) and cultured until the first molt. Ovigerous females, larval observations and dissection  were made using a estereomicroscope equipped with camera lucida. Embryonic stages and zoeaeI observations were made with a microscope equipped with differential interference contrast (DIC).   Preliminary results show that in Puerto Madryn Bay, the female crab incubate embryos 15 - 20 days after fertilization. After this period a pre-zoeae emerge, with a very short lifetime (5 to 10 min.). Then the pre-zoeae stretches its rostral and caudal spines and passes to first zoeae. In this study the zoeaeI didn’t reach subsequent stages.   The morphological description of the ovigerous female, the embryos and their distribution inside the abdomen is given. The detailed description of zoeaeI buccal pieces, legs, caparace, tail and rostral and caudal spines together with their lengths are added.