Virgin Spinedace larvae and early juveniles-A descriptive account

Authors: Snyder, Darrel E.*, Sea, Sean C., Bjork, C. Lynn

Year: 2015 (xlvii)

Abstract

The Virgin Spinedace, Lepidomeda mollispinis mollispinis (Cyprinidae), is endemic to, and still persists in, the Virgin River Basin. As an imperiled resident of the Virgin River, the subspecies is protected by the states of Arizona, Nevada, and Utah and currently under renewed review for designation as threatened or endangered by the US Fish and Wildlife Service. It is one of just six fishes (all cypriniforms) native to the river and one of two therein belonging to a small group of cyprinids referred to as plagopterins (former tribe Plagopterini), most species of which are uniquely characterized by spinous modifications to the pelvic fin rays and the first principal and adjacent rudimentary rays of the dorsal fin. To document the morphological ontogeny of its previously undescribed larvae and facilitate researcher identification of collected specimens, the Virgin River Resource Management and Recovery Program (with funding by Washington County Water Conservancy District, UT) sponsored developmental study, illustration, and description of Virgin Spinedace larvae and early juveniles. Specimens for study and reference were reared, preserved, and provided in 2011 by Dexter National Fish Hatchery and Technology Center (NM; now the Southwestern Native Aquatic Resources & Recovery Center). As presented in this poster, most results were summarized in the standard species-account format of the Larval Fish Laboratory. Copies of the 2013 descriptive account may be viewed also at, or downloaded from, the Virgin River Program website (http://www.virginriverprogram.org/wp-content/uploads/2011/08/Finalreport-Virginspinedacedescription-r.pdf). Larvae and early juveniles of the Big Spring Spinedace, L. m. pratensis, a federally threatened resident of Meadow Valley Wash, NV, are likely very similar.