Coptidium x spitsbergense ( Hadac ) Luferov & Prob.

Gillespie, Lynn J., Saarela, Jeffery M., Sokoloff, Paul C. & Bull, Roger D., 2015, New vascular plant records for the Canadian Arctic Archipelago, PhytoKeys 52, pp. 23-79 : 53-55

Coptidium x spitsbergense ( Hadac) Luferov & Prob. Fig. 18

Ranunculus x spitsbergensis Hadač

Common name.

Spitzbergen buttercup

Distribution.

Disjunct circumpolar

Comments.

Our collections are the first of this species for the CAA. The species is considered to be a sterile triploid hybrid between Coptidium lapponicum (L.) Rydb. and Coptidium pallasii (Schltdl.) Tzvelev, and exhibits an intermediate morphology and habitat preference ( Cody et al. 1988, Elven and Murray 2008). All three species were previously treated within Ranunculus L. ( Porsild 1957, Porsild and Cody 1980, Cody et al. 1988, Whittemore 1997, Aiken et al. 2007), but they differ both genetically and morphologically (presence of thick white underground stems, fragrant flowers, three sepals, spongy tissue in achene) from other members of the genus ( Hörandl et al. 2005). Coptidium x spitsbergense , also known from Svalbard and the Russian Arctic, was first recorded in North America by Cody et al. (1988) from one site in southern mainland Nunavut, and four sites in northwestern Arctic Quebec. The hybrid is most similar in habit and leaf morphology to Coptidium pallasii , but differs in its smaller, pale yellow flowers. The taxon was not treated by Whittemore (1997) for North America.

Coptidium x spitsbergense was found at two sites in the Soper River valley growing in sedge meadows, in wet moss adjacent to ponds. Associates at the first site (Saarela et al. 2194) include Carex bigelowii and Salix arctophila , at the second site Betula glandulosa , Empetrum nigrum , Eriophorum angustifolium , Eriophorum scheuchzeri , Rhododendron tomentosum subsp. decumbens , Carex spp. and Salix sp. Only one parent, Coptidium lapponicum , was found nearby at the Saarela et al. 2419 site (parents were not looked for at the other site), growing scattered in moist mossy tundra. The other parent, Coptidium pallasii , has not been collected in the Soper River valley and was not observed during our fieldwork there, but one older collection is known from the vicinity of Kimmirut (Polunin 1173, CAN; Aiken et al. 2007). Elsewhere the hybrid species is also often found in the absence of one (usually Coptidium pallasii ) or even both parents. In Svalbard it is more common than either parent and occurs in large stands usually in the absence of one or both parents ( Elven and Murray 2008, http://svalbardflora.no/). Cody et al. (1988) recorded Coptidium lapponicum as present at all five sites in Canada, and Coptidium pallasii as present at only two sites, both in northern Quebec.

Throughout its range fruiting specimens have not been observed. Plants are assumed to be spread mainly by bird dispersal of stem-shoot fragments ( Elven and Murray 2008, Elven et al. 2011). However, Cody et al. (1988) considered there to be no evidence for long distance dispersal and suggested that separate hybridization events occurred at each locality sometime in the past.

Specimens examined.

Canada. Nunavut: Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, Soper River valley, W bank, ca. 12 km S of Mount Joy, meadow along river opposite Group/Warden Cabin #7, 63°9'50"N, 69°39'55"W, 40 m, 8 July 2012, Saarela, Gillespie, Sokoloff & Bull 2194 (ALA, CAN-602059, O); Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, Soper River, 18.5 km downstream (S) of its confluence with the Livingstone River, 2 km S of Emergency Cabin #8, E bank of river, 62°59'2"N, 69°43'1"W, 20 m, 14 July 2012, Saarela, Gillespie, Sokoloff & Bull 2419 (ALA, CAN-602060, MT, O, WIN).