Arenaria longipedunculata Hulten, 1966

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 : 43

Arenaria longipedunculata Hulten

Common name.

Long-stemmed sandwort

Distribution.

Arctic-alpine amphi-Beringia-North America

Comments.

Our collections are the first records of the species for the CAA and Nunavut. Described by Hultén (1966) from Arctic Alaska, this species was considered conspecific with Arenaria humifusa by Porsild and Cody (1980), but has most recently been treated as a separate species ( Cody 2000, Hartman et al. 2005, Elven et al. 2011). While considered to have an amphi-Beringian distribution, Elven et al. (2011) suggested that the species may also be present in the CAA and Greenland based on the results of a phylogeographical analysis of AFLP data ( Westergaard et al. 2011), a hypothesis supported here. Our collections from southeastern Victoria Island (det. R. Elven) and Baffin Island were identified as this species based on the character combination of long pedicels (10-20 mm) with glandular villous pubescence (not very short retrorse), flowers long-exserted above the leaves, sepals glandular villous basally, and leaf blade margins ciliate proximally (at least sparsely) ( Hartman et al. 2005). We found that pedicel length varied among collections and was sometimes shorter than the range given for Arenaria longipedunculata (10-20 mm) in Hartman et al. (2005); however, other characters were consistent with our identification. Pedicels are 10-20 mm (Saarela et al. 2776) and 5-10 mm long (Saarela et al. 2477) on the Baffin Island collections, and 9-12 mm long (Gillespie et al. 7721) on the Victoria Island collection (flowers were still in bud with pedicels up to 6 mm long on Gillespie et al. 8136). Plants were small and tufted, and were growing in moss on moist to wet riparian meadows on Victoria Island and in mossy tundra at base of slopes or cliffs on Baffin Island.

The ranges of Arenaria longipedunculata and Arenaria humifusa overlap in the Arctic Islands; indeed we collected both species in the Soper River-Kimmirut area on Baffin Island, and both on Victoria Island but in different localities. In northern Quebec and Newfoundland some large specimens identified as Arenaria humifusa appear to approach Arenaria longipedunculata in some characters; these robust matted plants have elongate stems with long internodes and pedicels. Further study of this species complex is needed to determine more precisely species boundaries and distributions and to determine if hybrid or introgressed populations exist in the Canadian Arctic.

Specimens examined.

Canada. Nunavut: Kitikmeot Region, Victoria Island, vicinity of river flowing into Clauston Bay, 3-4 km from river mouth, 69°2'39"N, 113°25'15"W, 10-20 m, 8 July 2008, Gillespie, Saarela, Consaul & Bull 7721 (CAN-592340); Kitikmeot Region, Victoria Island W end of Johansen Bay at mouth of Mackenzie Creek, 68°36'4"N, 111°21'7"W, 0-20 m, 20 July 2008, Gillespie, Saarela, Consaul & Bull 8136 (CAN-593142); Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, Soper River, 18.5 km downstream (south) of its confluence with the Livingstone River, 2 km south of Emergency Cabin #8, west side of river, 62°59'20"N, 69°43'41"W, 36 m, 15 July 2012, Saarela, Gillespie, Sokoloff & Bull 2477 (CAN-601731); Qikiqtaaluk Region, Baffin Island, Kimmirut, west end of Fundo Lake, ca. 2 km west of hamlet, 62°50'44"N, 69°54'6"W, 40 m, 22 July 2012, Saarela, Gillespie, Sokoloff & Bull 2776 (CAN-601732).