Thecate Hydroids from the Shelf Waters of Northern Canada

Abstract

Based largely on collections from the Calanus–Salvelinus expeditions, 54 species of thecate hydroids were identified from the shelf waters of northern Canada between northeastern Newfoundland and the Alaska–Yukon border. Common species included Halecium muricatum, Calycella syringa, Campanularia integra, C. speciosa, C. volubilis, Gonothyraea loveni, Filellum serpens, Lafoea gracillima, Sertularella polyzonias, S. tricuspidata, Sertularia schmidti, and S. similis. Halecium groenlandicum, H. scutum, Cuspidella procumbens, Calycella gracilis, and Sertularia schmidti are new records for North America; Ptychogena lactea is previously known from this continent only as the medusa. Twenty-two species are reported in northern Canada for the first time, bringing to 71 the number of thecate species recorded from the region. Nearly half of the 71 species recorded are circumpolar in distribution, and over two-thirds transgress both arctic and subarctic zones.Most samples had a paucity of hydroids, particularly those from the high arctic. Collection records indicate that the most favourable regions for hydroids in northern Canada are the Strait of Belle Isle, eastern Ungava Bay, eastern Hudson Strait, northern and southeastern Hudson Bay, Foxe Channel, and northern Foxe Basin.

Additions to the hydroids (Cnidaria, Hydrozoa) of the Bay of Fundy, northeastern North America, with a checklist of species reported from the region

“…Meanwhile, on the basis of biogeography and apparent temperature tolerances of the species, records of O. bidentata from the Antarctic Ocean (reviewed in Peña Cantero & Gili 2006) seem open to reconsideration. In the northern hemisphere, this hydroid is primarily a temperate zone species that does not penetrate far into boreal waters (Fraser 1944;Cornelius 1988Cornelius , 1990Cornelius , 1995b; this study), and it is completely absent in subarctic and Arctic regions (Naumov 1960;Calder 1970;Schuchert 2001a;Antsulevich 1915). Also worthy of further investigation is the identity of a population of hydroids resembling O. bidentata, but having very small colonies (<1 cm) and small hydrothecae, that inhabits oligohaline areas at the head of estuaries on the Atlantic coast of the United States.…”

“…Bay of Fundy: recorded for the first time. Eastern North America: Foxe Basin and Greenland to southern Massachusetts (Fraser 1944, 1947aCalder 1970;Schuchert 2007).…”

“…In turn, H. mirabile and H. repens have often been considered synonyms or questionable synonyms of H. curvicaule Lorenz, 1886(Dons 1912Broch 1918;Schuchert 2001a), a hydroid of Arctic and higher boreal waters. That species differs from H. praeparvum in having female gonothecae with a lateral aperture and with pronounced ribs on the dorsal wall, internodes that are long and slender, and hydrothecae with nearly straight walls (Naumov 1960;Calder 1970;Schuchert 2001b;Antsulevich 2015). Curiously, illustrations of the female gonothecae of hydroids identified as H. curvicaule by Dons (1912: figs.…”

“…The same error exists in Fraser's (1937) account of the species from Alaska and the Pacific coast of Canada (Choong 2015;Antsulevich 2015). Likewise, my records of S. polyzonias from the Canadian north (Calder 1970), from Cape Cod Bay (Calder 1975), and from Northumberland Strait (Calder 2004) were based instead on S. gigantea. No specimens corresponding with S. polyzonias were observed during this study in collections from the Bay of Fundy, whereas hydroids of S. gigantea were frequent.…”

“…gigantea); Northern Foxe Basin (Calder 1970, as S. polyzonias) to Nantucket, Massachusetts (Fraser 1944).…”