Caligus pelamydis Krøyer 1863

Caligus pelamydis Kroyer, 1863

Caligus pelamydis Kroyer, 1863:124.

Caligus scomberi Bassett-Smith, 1896:11.

Caligus scombri Scott, T., 1901:148.

Parapetalus sp. Silas and Ummerkutty, 1967:908.

This species has been recorded many times from scombrid and non-scombrid hosts (see Lewis, 1967: 139). Shiino, 1965 and Lewis, 1967 have provided good descriptions of this species. We will discuss only those features of special taxonomic importance in addition to including figures. A complete synopsis of the literature has been provided by Margolis, Kabata, and Parker, 1975:59.

MATERIAL EXAMINED.—30 collections containing 97 and 4 from the gill arches, gills, and inner wall of the operculum of the following hosts and localities: Scomber scombrus from France; Scomber japonicus from Gulf of Mexico, Florida (Atlantic), Gulf of Guinea; Scomberomorus niphonius from Japan; Auxis species from New South Wales; Euthynnus affinis from New South Wales; Euthynnus alletteratus (locality unknown); Sarda sarda from Argentina, Gulf of Guinea, Tunis, South Africa (Port Elizabeth); Sarda australis from New South Wales; Sarda chiliensis lineolatus from California.

FEMALE.—Body form as in Figure 64a. Range of total length 3.00–4.65 mm. As in other species of Caligus with widespread distribution, the size differences seem to be correlated with water temperature rather than host species.

Caligus pelamydis females can be separated from other species of Caligus found on scombrids by the following combination of characters: cephalon 40–45 percent of total length; abdomen 23–25 percent of total length; second and third segments of leg 2 endopod (see Figure 65e) each with a large patch of fine spinules along outer edge; leg 4, 3-segmented with last segment produced distally to give segment a triangular shape (see Figure 66b) and prominent fringes at bases of all setae, tines of sternal furca spatulate and as wide or wide than base (Figure 65c).

MALE.—Body form as in Figure 66c. Range of total length 2.48–2.55 mm (based on 3 specimens from Sarda sarda, Gulf of Guinea). Males are generally rare in collections (comprising only about 4 percent of the total sample studied). Shiino (1965:411), described the male of this species comparing it to an immature female in the same collection. Certain appendages differ between the sexes but some of those noted by Shiino were probably due to the immaturity of the female. In our sample we found the following differences based on adults of both sexes: second antenna of male with rugose patch along posterior edge of basal segment; postoral process of male (Figure 66e) with rugose patch on basal half; maxilliped of male (Figure 66f) with sclerotized process on basal segment opposing tip of claw; fifth and sixth legs represented by 3 setae at mid-margin and 2 setae at posterior corner of genital segment respectively; abdomen 2-segmented with first segment about half as long as second (Figure 66d).

Caligus pelamydis Krøyer, 1863

Caligus pelamydis Krøyer, 1863;124.—Cressey and Cressey, 1980:32.

British Isles; North Sea; North and South Atlantic; Baltic Sea; Adriatic Sea; Mediterranean; Gulf of Mexico; Gulf of Guinea; Hawaii; New Zealand; New South Wales; Argentina; coast of California;