Branchinecta mackini Dexter, 1956

New records. OREGON: Lake County: Pool east of intersection of Highway 97 and Highway 161, on north side of Indian Tom Lake, 17 March 1998, D.C. Rogers, C.L. Rogers, DCR-123. Christmas Lake, May 1999, reared from soil on 20 March 2000, D.C. Rogers, DCR-211. Bottomless Lake, May 1999, reared from soil on 20 March 2000, D.C. Rogers. Pool on Highway 31 near Clover Flat Road, north of Valley Falls, 2 May 1999, D.C. Rogers, C.L. Rogers. WASHINGTON: Grant County: Lake Lenore II, Large pool, N47 ˚30’ 15’’, W 119˚ 30’ 15’’, 13 April 1999, R. E. Hill, DCR-287. Pool on Lower Crab Creek Road, approximately 8 km east of Beverley, north side of Crab Creek, south side of road, just before bridge across Crab Creek, 30 March 2007, D. C. Rogers, H.L. Rogers DCR-683. Roadside salt pool 10.1 miles west of Othello on highway 26; 30 March 2007; M. A. Hill, D. C. Rogers; DCR-684.

Comments. This widespread species is typically found in turbid alkaline pools. We found it in clear, saline pools in Grant County, Washington, in sites originally reported by Lynch (personal notes and specimens) to hold B. campestris . In one site (DCR-684) B. mackini was co-occurring with A. franciscana, in much the same way that B. campestris co-occurs with A. franciscana . The B. mackini were swimming in the unmixed freshwater layer (from recent precipitation) lying over the hypersaline water of the pool (Eriksen and Belk 1999). This represents the first published record of these two species co-occurring.