Novel mode of postembryonic development in Ammothea genus (Pycnogonida: Ammotheidae) from Antarctic waters

Abstract

In this paper the postembryonic development of Ammothea glacialis (family ammotheidae) is described. The studied material was collected during the Italica XIX cruise to Victoria land, ross sea, antarctica. The external morphology of three larval instars is described and illustrated. The development of A. glacialis has the following characteristics: (1) protonymphon hatch from the eggs; (2) the larvae have yolk reserves and relatively large size (0.7 mm in length); (3) the larvae remain on the ovigerous legs of males during several moults; (4) the larvae have reduced larval II-III appendages and the spinning apparatus is absent; (5) the development of walking legs is sequential. This development is compared with those previously known, especially with Propallene longiceps and Nymphon grossipes.

Nuevo modo de desarrollo postembrionario en el género AmmotheA (Pycnogonida: Ammotheidae) procedente de aguas Antárticas. – En este trabajo se describe el desarrollo postembrionario de Ammothea glacialis (familia ammotheidae). El material estudiado fue recolectado durante el crucero Itálica XIX a Tierra Victoria, en el mar de ross, antártida. se describe e ilustra la morfología externa de tres estadios larvarios. El desarrollo de A. glacialis se caracteriza por: (1) la larva eclosiona como protonymphon; (2) la larva es de tamaño relativo grande (0.7 mm de longitud) y con reservas de vitelo; (3) la larva permanece en los ovígeros del macho durante varias mudas; (4) la larva presenta los apéndices larvarios II y III reducidos y el “spinning apparatus” está ausente; (5) el desarrollo de las patas es secuencial. Este desarrollo es comparado con otros desarrollos postembrionarios previamente conocidos, especialmente con los de Propallene longiceps and Nymphon grossipes.