Hyperia galba (Montagu 1813)

Hyperia galba (Montagu)

Cancer gammarus galba Montagu, 1813:4, pl. 2; fig. 2.

Hyperia galba (Montagu).–Guerin, 1825:771.–Bovallius, 1889:180–188, pl. 10: figs. 25–32 [literature, synonymy].–Stephensen, 1923:17–19, chart 3 [distribution]; 1924:81–83, chart 11; 1944:9.–Shoemaker, 1920:24E; 1926:3; 1955:71.–Chevreux and Fage, 1925:401–402, fig. 401.–Behning, 1939:354.–Dunbar, 1942:37; 1954:783 [distribution]; 1963:3 [distribution].–Schellenberg, 1942:241–242, fig. 202.–Hollowday, 1946:passim [association with medusae].–Bousfield, 1951:138; 1956:144.–Certain, 1953 [chromosomes]; 1960 [chromosomes].–Alvarado, 1955:219–220.–el Maghraby and Perkins, l956:494.–Vinogradov, 1956:210.–Dahl, 1959a;1959b [evidence for ectoparasitism].–Oldevig, 1959:125.–Bowman, Meyers, and Hicks, 1963:140–146, figs. 1, 2e-h.–Bulycheva, 1964:317–318.–Metz, 1967 [association with medusae].

DERIVATION OF NAME.–Presumably from the Latin “galbus” [=yellow], referring to color of the animal.

TYPE-LOCALITY.–South coast of Devonshire, England.

DIAGNOSIS.–Head shorter than pereonites 1–2 combined; gland cone rather pointed. Posterolateral corner of pleonal epimeron 3 ending in small point; posterior margin moderately convex. Outer lobe of Mxp with a few short setae along inner margin; inner lobe about ¾ as long as outer lobe. Surfaces of s6 and s7 of P1–P2 with relatively few setae, those of s6 not extending past serrate posterior margin of base of dactyl. S5 of P3–P4 with a few short setae; posterior margin of s6 finely serrate, without setae. S2 of P5–P7 rather narrow; P5 without setae, P6–P7 with cluster of setae at distal corner of s2. Length of adult ♂ and ♀, 10–24 mm.

DISTRIBUTION.–As Bulycheva (1964) has pointed out, Hyperia galba is limited to the Arctic and the cooler regions of the northern Atlantic and Pacific Oceans. It has been reported from the South Atlantic, Antarctic, and Indian Oceans, but none of these records is supported by illustrations or descriptions. Some have resulted from the authors considering H. spinigera, a valid and distinct species, to be a junior synonym of H. galba. I list below the published records of Hyperia galba that I consider unacceptable. Bulycheva (1964) also considers the Antarctic and Indian Ocean records of H. galba to be erroneous.

Doubtful and Erroneous Records of Hyperia galba

H. galba has a circumpolar distribution in the Arctic Ocean (Bulycheva, 1964). In the western Atlantic it extends south to Chesapeake Bay (Bowman, Myers, and Hicks, 1963), and in the eastern Atlantic it reaches the coasts of England, France, and Spain (Stephensen, 1923, 1924; Alvarado, 1955). It is said to have been collected from numerous localities in the areas surrounding the Azores by Prince Albert Ier of Monaco (Chevreux, 1900, 1935; Pirlot, 1939); these identifications require confirmation, since they are at or beyond the southern boundary for this species. It is the only hyperiid occurring in the Baltic. It is apparently absent from the Mediterranean (Stephensen, 1924), although some authors (e.g., Chevreux and Fage, 1925; Spandl, 1927; Pirlot, 1929) include the Mediterranean within its range.

Records of H. galba from the Pacific are much fewer than those from the Atlantic. Derjavin (1927) recorded it from Avachinska Inlet (at Petropavlovsk) on the Kamchatka Peninsula. Behning (1939) reported it from the Bering, Okhotsk, and Japan Seas, without giving specific localities. Buycheva (1964) considers the Japan Sea record erroneous. Vinogradov (1956) found it in the western Bering Sea, the Gulf of Anadir, the Kamchatka region, and the waters of the Kurile-Kamchatka Trench. Yoo (1971) found it off Japan north of 37°50′N. None of these western Pacific records is supported by descriptions or illustrations.

In the eastern Pacific H. galba was reported from Puget Sound by Caiman (1898), and from southern California by Brusca (1967a, 1967b), but it is likely that these authors actually had the hystrix form of H. medusarum. The USNM has specimens of H. galba from four localities near the Alaska Peninsula: Kodiak; Unalaska; St. George I., Pribilof Is.; and in the Bering Sea east of the Pribilof Is. (Albatross sta. 3540, 56°27′N, 166°08′W). I have not seen specimens of H. galba from elsewhere in the Pacific in spite of examing numerous specimens of Hyperia collected by towing nets and trawls and by removing them from medusae. Apparently it does not occur off the Pacific coast of Canada or the contiguous United States.

Compared with H. medusarum, H. galba is abundant in the Atlantic and scarce in the Pacific. The distribution of the two species in the Atlantic is considered below.

Comparison of Atlantic Distribution of Hyperia medusarum and H. galba

Both H. galba and H. medusarum are Arctic-Subarctic-Boreal species associated with scyphomedusae. Is there competition between the two species or is this avoided by niche differentiation? So little is known of the habits and ecological requirements of the two species that I can only summarize what I have gleaned from published works.

H. galba seems to be by far the more abundant species in the Atlantic. Stephensen (1924) reports that the Thor obtained 615 specimens of H. galba from 40 stations, mostly southwest of Ireland, and only 2 specimens of H. medusarum from 2 stations. The Ingolf (Stephensen, 1923) collected about 20 specimens of H. galba from 6 stations, mostly north of 60°N, but failed to collect H. medusarum. From plankton collections in Ungava Bay, Dunbar (1954) reported 12 specimens of H. galba from 4 stations and 2 specimens of H. medusarum from 2 stations. Collections in Belle Isle Strait, reported on by Bousfield (1951), yielded 13 specimens of H. galba from 4 stations and only 1 specimen of H. medusarum. Collecting from Cyanea capillata, Hicks obtained 120 H. galba and 1 H. medusarum in Narragansett Bay, and 57 H. galba and 3 H. medusarum in the Niantic River, Connecticut (Bowman, Meyers, and Hicks, 1963).

The host preferences of the two species are not known. Both have been found associated with Aurelia, Chrysaora, Cyanea, and Rhizostoma. In addition, H. medusarum has been taken from Thaumantias (Stephensen, 1923), and young individuals of H. galba may be found on the hydromedusan Melicertidium octocostatum (Schellenberg, 1942). Occasionally H. galba may be found on the ctenophore, Beroe (Stephensen, 1923; Schellenberg, 1942). Dales (1966) states that H. medusarum is associated with Rhizostoma pulmo, whereas H. galba occurs with Rhizostoma octopus and Chrysaora hyoscella. Dales does not document this statement nor say whether it is his own observation. Experimental studies of host preference might aid us to understand the differences between these two species of Hyperia.

Comparing the occurrence of the two species off the west coast of Ireland, Tattersall (1906) suggested that H. medusarum was a more distinctly oceanic form than H. galba. According to Schellenberg, H. galba penetrates farther into the Baltic, reaching Warnemünd, whereas H. medusarum only reaches the Great Belt (Store Baelt). Metz (1967) reports that H. galba is abundant in the Isefjord Area of Denmark (S 17.6–21.8‰), but does not mention H. medusarum.

H. galba extends farther south in the Atlantic than H. medusarum, reaching at least to the latitude of the coast of Spain (Alvarado, 1955). According to Schellenberg (1942) H. medusarum does not penetrate the inner North Sea, and its absence from Chevreux and Fage’s (1925) volume on the amphipods in the Faune de France series indicates that it does not occur on the Atlantic coast of France. In the eastern Atlantic the presence of H. galba and the absence of H. medusarum from Cheasapeake Bay (Bowman, Meyers, and Hicks, 1963) also suggests a tolerance for higher temperature in H. galba.