Hysterothylacium sp.

Moravec, F. & Nagasawa, Kazuya, 2000, Some anisakid nematodes from marine ® shes of Japan and the North Paci ® c Ocean, Journal of Natural History 34 (8), pp. 1555-1574 : 1571

Hysterothylacium sp. fourth-stage larvae

( Figure 7G ±L)

Description

Larvae (seven specimens from A. argentatus ; measurements of one specimen from P. heterura in parentheses). Length of body 3,898±7621 (11,289), maximum width 131±209 (247). Anlagen of lips well developed, 18±32 (24) long. Oesophagus 320± 547 (705) long; size of ventriculus 26±48 Ö 42±60 (60 Ö 64); ventricular appendix 552±853 (1470) long, appearing to be twofold inside. Anterior intestinal caecum 116±172 (156) long. Length ratio of caecum and ventricular appendix 1: 4.8±5.0 (1:9.4). Nerve ring and excretory pore 128±196 (331) and 140±220 (339), respectively, from anterior extremity. Anlagen of sexual glands tubular; anlage of vulva 1914±3584 (not established) from anterior end of body. Tail conical, 84±136 (116) long, with rounded tip bearing numerous small cuticular spines.

Hosts. Argyrosomus argentatus (Houttuyn) ( Sciaenidae , Perciformes ) and Parapteroide s heterura (Bleeker) ( Scorpaenidae , Scorpaeniformes ).

Site of infection. Body cavity.

Localities. A. argentatus : East China Sea , oOE Shimabara , Nagasaki Prefecture , Kyushu Island (8 July 1988); P. heterura : North Paci ®c Ocean, oOE Yui, Suruga Bay, Shizuoka Prefecture, Honshu (9 December 1996) .

Comments

The larvae originating from both host species are morphologically identical and, therefore, they can be considered conspeci®c. Since they were found encapsulated in the abdominal cavity, it is apparent that their ®sh hosts serve as only the second intermediate hosts or, more probably, as paratenic hosts.

Figures

FIG. 7. (A±F) Hysterothylacium auctum (Rudolphi, 1802) from A. argentatus, male: (A) anterior end; (B,C) cephalic end, dorsal and ventral views; (D) posterior end; (E) tail; (F) tail tip. (G±I) Hysterothylacium sp. fourth-stage larva from Argyrosomum: (G) tail; (H) cephalic end, lateral view; (I) anterior end. (J±L) Hysterothylacium sp. fourthstage larva from Parapteroides: (J) anterior end; (K) cephalic end, lateral view; (L) tail. Scale bars in mm.