Family HEXOSTOMATIDAE Price, 1936

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Introduction

The Hexostomatidae are characterised as follows: Haptor clearly or nor clearly set off from body proper, usually with 3 or 4 pairs of sessile clamps been modified into suckers each containing three irregular shaped and dissimilar sclerites Posterior (inner) suckers usually reduced in size, and of other pairs two or more may be absent on one side, and they may be unequal in size. Two pairs of anchors usually present between two posterior clamps, but there is no terminal lappet; they are attached directly to the hind margin of the body. Small paired oral suckers and pharynx present. Intestine broken up into network extending throughout or most of body length. Testes divided into numerous follicles in postovarian intercaecal field. Common gential pore or atrium armed or unarmed. Ovary extensively coiled or plicated. Genito-intestinal canal present. Eggs filamented. Vagina with usually armed middorsal pore, median vaginal duct dividing into two long parallel canals which join the paired vitelline ducts posteriorly.

Hexostomatids are parasites of scombroid fishes (Yamaguti 1963). Type-genus: Hexostoma Rafinesque, 1815.

The haptoral attachment of Hexostoma spp. to the secondary gill lamellae of their host (Thunnus spp.), compresses gill tissue which stimulates tissue swelling. This mechanism of attachment appears to consolidate their attachment to tuna gills (Hayward 2005).

General References

Hayward, C. 2005. Monogenea Polyopisthocotylea (ectoparastic flukes). pp. 55-63 in Rohde, K. (ed.). Marine Parasitology. Collingwood, Victoria : CSIRO Publishing 592 pp.

Yamaguti, S. 1963. Systema Helminthum. Volume IV. Monogenea and Aspidocotylea. New York : Interscience Div., John Wiley & Sons Inc. 699 pp.

Yamaguti, S. 1963. Systema Helminthum. Volume IV. Monogenea and Aspidocotylea. New York : Interscience Div., John Wiley & Sons Inc. 699 pp. [203]

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