ANATOMICAL DESCRIPTION AND BIOLOGY OF THE SPLANCHNOTROPHID Splanchnotrophus gracilis HANCOCK & NORMAN, 1863 FOUND PARASITIZING THE DORIDACEAN NUDIBRANCH Trapania tartanella IHERING, 1886 AT THE RIA DE FERROL (GALICIA, NW IBERIAN PENINSULA)

作者：Abad M^*; Diaz Agras G; Urgorri V

来源：Thalassas: An International Journal of Marine Sciences , 2011, 27(2): 49-60.

• Splanchnotrophus gracilis
• Trapania tartanella
• SEM
• anatomical description
• infection rate
• parasitic load
• host damage

The genus Splanchnotrophus (Copepoda, Poecilostomatoida, Splanchnotrophidae) is a small group of endoparasites infesting certain shell-less marine opisthobranchs. The present study is focused on the type species Splanchnotrophus gracilis Hancock & Norman, 1863 and its relationship with its host, the doridacean nudibranch Trapania tartanella Ihering, 1886. This nudibranch presents large populations at the Ria de Ferrol, frequently found on the porifera Desmacidon fructicosum with a large part of specimens parasitized. The parasite female is exteriorly visible due to the presence of ovigerous sacs. In most of the nudibranchs the parasite can be directly observed through the almost transparent integument of the host. The females, much larger than the males and with a highly modified anatomy, take up the posterior body cavity of T. tartanella, clutching the gonad and digestive gland with their long body appendages. Males move freely within the interior of the body of the host, although they preferably position themselves near the female and along the reproductive system of the nudibranch. Generally, at least a single female of S. gracilis appears per nudibranch specimen. In the case of males, they appear in a number varying from 1 to 4.
The collection of specimens was carried out by means of autonomous diving. In the present work a description of the species Splanchnotrophus gracilis using Scanning Electronic Microscopy (SEM) and light microscopy is presented. New data on the biology of this species is given. High infection rates (94%) and parasitic loads (up to 43 parasites per host) were found. No clear damage has been found in the infected viscera of T tartanella or during the reproductive process, as normal copulations and spawns were observed in lab conditions. However, data suggest that a higher mortality exists in those specimens presenting a higher parasite load.

• 出版日期2011-7