Taxonomy of the Speckled Dace Species Complex (Cypriniformes: Leuciscidae, Rhinichthys) in California, USA Author Moyle, Peter B. Center for Watershed Sciences & Department of Wildlife, Fish and Conservation Biology, University of California, 425 LaRue Road, Davis CA 95626 USA. Author Buckmaster, Nicholas California Department of Fish & Wildlife, 787 Main Street, Bishop, CA 93514 USA. Nick. buckmaster @ wildlife. ca. gov Department of Animal Science, University of California, Davis, 1 Shields Avenue, Davis CA 95616 USA. syxsu @ ucdavis. edu Corresponding author. pbmoyle @ ucdavis. edu; https: // orcid. org / 0000 - 0002 - 4825 - 4865 Author Su, Yingxin 0000-0002-4825-4865 pbmoyle@ucdavis.edu text Zootaxa 2023 2023-03-06 5249 5 501 539 http://dx.doi.org/10.11646/zootaxa.5249.5.1 journal article 10.11646/zootaxa.5249.5.1 1175-5326 7701357 F146B808-9D5B-477F-9E73-09A8DFDBFA31 Rhinichthys klamathensis klamathensis , new combination , Klamath Speckled Dace, Fig. 6 Synonymy . Same as for Western Speckled Dace, R. klamathensis . Holotype and paratypes are the same as for Western Speckled Dace , R. klamathensis . Diagnosis . Same as Western Speckled Dace , R. klamathensis ; the Speckled Dace lineage that is abundant in the streams, lakes, and other aquatic habitats in the Klamath River Basin in Oregon and California , including the Trinity River in California . Distinguished statistically by having somewhat smaller scales (scales in lateral line, 68–78; mean 73, n =49) than the other two subspecies (Sacramento, 54–83, mean 70, n=123; Warner, 68–71, mean 69, n=58). Otherwise, it is not distinguishable from other Speckled Dace except by genomics and distribution . Description. Evermann and Meek (1898) described this cryptic subspecies as Agosia klamathensis . Therefore, the description quoted in the Western Speckled Dace account is also for this subspecies, and it applies to the other two subspecies as well. FIGURE 6. Top. Holotype, Lahontan Speckled Dace, from Rutter (1903) . Middle, Long Valley Speckled Dace from Whitmore Marsh, 2014, showing life colors. Photo by Jacob Katz. Bottom: Western Speckled Dace, type specimen, from Evermann and Meek (1898) . Distribution . The Klamath Speckled Dace is found throughout the Klamath Basin in Oregon and California , including the Klamath and Trinity rivers and tributaries, as well as in the Rogue River to the north (Wiesenfeld et al. 2017). It is also widespread in the upper Klamath Basin, including Upper Klamath Lake. The Speckled Dace in the Eel River, to the south of the Klamath Basin, is an introduced population of R. k. klamathensis ( Kinziger et al. 2011 ) . Geology/zoogeography. The geologic history of the Klamath region is complex. The Snake River, now a tributary to the Columbia River, was once a major river that originated in the Idaho region and flowed to the ocean via the ancestral Klamath River during the Pliocene ( Minckley et al. 1986 , Smith et al 2017 ). When the Snake broke through to the Klamath, it carried with it the lake fauna of the Great Basin, which gave rise to the presentday endemic, freshwater-dispersing fish fauna (12 species) of the upper Klamath basin ( Moyle 2002 ), presumably including Speckled Dace. Pfrender et al. (2004:498) , using a molecular clock based on mtDNA from Speckled Dace from the major river basins of Oregon , speculated that “…the levels of sequence divergence in R. osculus among these major basins are more consistent with a Pliocene or Miocene sundering of gene flow between major basins. Miocene isolation of these river systems is substantially earlier than has previously been suggested.” They thought such ancient divergence could explain the genetic diversity found in dace within the Klamath basin, a diversity that was also documented by Wiesenfeld et al. (2017). See also the geology discussion under Western Speckled Dace. Geographically, Klamath Speckled Dace co-occur with other fish species endemic to the Klamath watershed. However, the endemic fishes in the upper watershed (above Klamath Falls) are different from those in the lower river and it appears that dace from the two regions diverge as well, a situation noted also for Marbled Sculpin, Cottus klamathensis ( Daniels and Moyle 1984 ) . Genetics/genomics. The genomic study of Su et al. (2022) unveiled the three lineages within R . klamathensis , as discussed. Within the Klamath drainage, Wiesenfeld et al. (2017:8), using analyses of microsatellites and mtDNA, found that The Klamath–Trinity Basin Speckled Dace were resolved as nearly monophyletic [bootstrap ( BS ) 77], and exhibited a sister group relationship with nearby basins in California and Oregon ( Sacramento , Pit River , and Goose Lake ). The Klamath River and Trinity River populations, however, were found to be sufficiently distinct to suggest the two rivers were once isolated from one another, with their connection being fairly recent. The presence of apparent hybrids in the region where the two rivers meet today also supports this conclusion ( Wiesenfeld et al. 2017). A genetically distinct population is also found in Jenny Creek , a tributary to the Klamath River that is largely in Oregon ( Wiesenfeld et al. 2017) . Pfrender et al (2004) used mtDNA to compare dace from the upper Klamath and Rogue rivers with those from two tributaries to the Columbia River in Oregon . They found species-level differences between dace in the two great watersheds, with estimated divergence times of 3.9 to 9.6 million years ago. Within the upper Klamath basin, Pferender et al. (2004) found considerable genetic structure but of more recent origin (<1 million years), including Jenny Creek as a distinct population. Overall, analysis of mtDNA data of dace from their entire range showed that dace from the Klamath, Sacramento, and Warner basins share much of the same lineage; together they form a separate lineage within the Northwest clade of Smith et al. (2017) . Note. The Klamath Speckled Dace was originally described as a species that differed from other Speckled Dace by having finer scales ( Evermann and Meek 1898 ). Subsequently, it retained its identity as a subspecies, R. osculus klamathensis . This is not surprising given that the Klamath Basin has long been recognized as an isolated basin which supports high endemism in its fishes ( Moyle 2002 ). The Klamath Speckled Dace has retained its identity through the region’s complex geologic history, enduring the rise of mountain ranges, high levels of vulcanism, and invading interior rivers ( Minckley et al. 1986 ). This complex geologic history has kept the Klamath fish fauna isolated and distinct. In the upper Klamath basin, Speckled Dace live with other endemic fishes that had their ancestors in the Great Basin. Even in the lower Klamath River, which is too swift for the lake-adapted fishes of the upper basin, it co-occurs with the endemic Klamath Smallscale Sucker, Catostomus rimiculus ( Moyle 2002 ) . Given the genetic structure that Wiesenfeld et al. (2017) found in the basin, it is possible that dace populations from the upper and lower river should be treated as separate subspecies. Su et al. (2022) confirmed results from other genetic methods that the Klamath Speckled Dace is a distinct evolutionary lineage. Etymology. The Klamath Speckled Dace is named for the river system to which it is endemic. The river is named for the native peoples who lived (and still do) in the upper Klamath Basin. Conservation Status. The Klamath Speckled Dace is widespread and abundant in streams and natural lakes in the Klamath Basin, including the Trinity River. The main concern is that some distinct populations, such as in Jenny Creek, may be lost as the waters are dammed and diverted. The genetic diversity of Speckled Dace populations within the river system is just beginning to be appreciated ( Pfrender et al. 2004 ; Wiesenfeld et al. 2017).