SHORT PAPERS

HISTOPATHOLOGY OF THE Munida iris A. Milne Edwards by Munidion PARASITIZATION OF MUNIDA IRIS irritans Boone. (: GALATHEIDAE) BY MUNIDION IRRIT ANS MATERIAL AND METHODS (ISOPODA: BOPYRIDAE) During July of 1973, 1974, and 1975, 6- day training cruises aboard the R/V ANNAN- Charles R. Bursey DALE of the Marine Science Consortium, Millersville, Pennsylvania, were undertaken ABsTRAcT-The bopyrid isopods, parasites of the branchial cavity of decapods, produce a lateral pro- with the objective of sampling benthic fauna tuberance in the carapace of their host. The large on the continental shelf from Hudson Can- female parasite obtains blood from the host by yon to Norfolk Canyon. Specimens were puncture of the dorsal branchial chamber cuticle. preserved in 10% formalin and later identi- The thickness of the deformed area of carapace is fied and counted. approximately twice that of the remaining carapace. Gill surfaces beneath the parasite exhibit deforma- Of 585 Munida iris collected during these tion and scar tissue is present. cruises, 14 exhibited a strong lateral pro- tuberance on a branchiostegite. Subsequent The family Bopyridae is composed of dissection showed that each protuberance parasitic isopods which are often found in contained a female M unidion irritans. A the branchial cavity of decapods (Richardson, diminutive male was found on the abdomen 1905; Tucker, 1931; Pike, 1953; Tuma, of the female in seven of the specimens. Ex- 1967; VanArman and Smith, 1970; Mark- amination of the gonophore of the parasit- ham, 1975). Sexual dimorphism is charac- ized crabs revealed that all were males. Of teristic of the group: the female is large, the 571 non-parasitized crabs, 348 (61%) often asymmetrical and responsible for the were males, 205 (36%) were ovigerous fe- lateral protuberance produced in the host's males and 17 (3%) were non-ovigerous fe- carapace. The male remains cryptoniscid males. in form (Naylor, 1972) and is usually found Portions of the deformed carapace and on the female's body near the genital open- impressed gill, as well as un infested carapace mgs. and gill were dehydrated in graded alcohols, There are probably more than 100 pub- cleared in cedarwood oil and embedded in lished papers that have made at least passing paraffin by conventional methods. Sections reference to the effects of bopyrids on their were cut at 10 .urn, stained in hematoxylin hosts. Attention has been focused on para- and eosin and examined by the light micro- sitic castration of the host species (Pike, scope. Whole parasites were dehydrated in 1953; Reinhard, 1956); the degree of modi- graded alcohols, cleared in cedarwood oil and fication of the host's pleopods is used to mounted in balsam. index the degree of castration (Perez, 1926). Other pathologies attributable to the pres- RESULTS ence of the female parasite have apparently In six of the 14 parasitized crabs exam- received little attention. Although it is gen- ined, the isopod parasite was found in the erally believed that the female feeds on the left branchial chamber (Fig. 1). In the other body fluids of the host (Barnes, 1974), feed- eight parasitized crabs, the parasite occupied ing methods of these parasites have appar- a corresponding position in the right bran- ently not been described. This paper presents chial chamber. The crabs ranged in size histological aspects of the parasitization of from 14 to 25 mm (carapace length). The 566 SHORT PAPERS 567 female parasites ranged from 9.5 to 18 mm in total body length. Associated male bopyrids were found in seven instances and ranged in length from 1.4 to 4.5 mm. The size of the carapace deformity was similar to the dimensions of the enclosed female para- site. In all cases the protuberance ap- proached the posterior free edge of the branchiostegite. The ventral surface of the parasite was directed dorsally and the head posteriorly with respect to its host: typical orientation of bopyrid parasites. The dorsal surface of the parasite was pressed against the