Branchinecta hiberna, a new species of fairy shrimp (Crustacea: Anostraca) from western North America

Abstract

The following description presents a new species of Branchinecta.This is the 40th species described in this genus, which achieves its greatest diversity in the Americas.Most species occur in vernal pools and other seasonal wetlands in the western United States and in Argentina.One species is reported from the Antarctic (Jurasz et al. 1983), and 6 are reported from Eurasia (Belk and Brtek 1995).This new species is the 24th anostracan reported from California, the 8th from Oregon, and 6th from Nevada.We each discovered this new species independently.Fugate reared specimens from soil samples collected from the Great Basin regions of Oregon, and Rogers collected live animals from the Great Basin regions of California, Oregon, and Nevada.Several biologists (Coopey 1946, Lynch 1972, C. Hunter personal communication) extensively sampled filled pools in this area, but none reported this species.Fugate sampled filled pools in the area during May 1993 and returned in October to collect soil samples.Rogers collected from filled pools in the area between the end of March and July 1987, 1989, 1990, and 1995 through 1999.Although numerous branchiopods were present April through June, the species described in this paper was not found until soil samples were hydrated in the laboratory or surveys were performed during the final winter months. METHODSDry soil samples were collected in October 1993.Pieces of the top 2-5 cm of soil from the bottoms of dry pools were collected and stored in resealable plastic bags until samples were removed for hydration.Samples of approximately 75 mL dry soil were hydrated with deionized water in 10-L glass aquaria.The aquaria were placed in a 4C walk-in cold room and aerated vigorously for 24 hours, stirred, and then gently aerated until the shrimp were fully grown.After 24-48 hours, incandescent lights were used to raise the temperature to 13-15C.Hatching under these conditions normally occurred in 3-5 days.Shrimp were fed with baker's yeast dissolved in deionized water.We collected live animals from pools in February and March 1998 in the Great Basin Desert regions of California, Oregon, and Nevada from pools that were thawed, partially covered with ice, or covered with a layer of ice or ice and snow.Collections were made with a dip net.Where animals were collected from clear water, we stalked each specimen individually due to the animal's strong avoidance of any disturbance in the water.