Rhinichthys klamathensis achomawi, Moyle & Buckmaster & Su, 2023

Moyle, Peter B., Buckmaster, Nicholas & Su, Yingxin, 2023, Taxonomy of the Speckled Dace Species Complex (Cypriniformes: Leuciscidae, Rhinichthys) in California, USA, Zootaxa 5249 (5), pp. 501-539 : 529-531

Rhinichthys klamathensis achomawi , new subspecies. Sacramento Speckled Dace.

Figs. 1 , 4D ,

Synonymy. See R. klamathensis account for subspecies synonymies.

Holotype: WFB-3171 ( Figure 1 ), 70 mm SL. Bear Creek at Pondosa Bridge , 1.6 km SW of Pondosa, Siskiyou County, California. 41.1884°N - 121.700667°W. July 20, 2015. Jason Baumsteiger, Mollie Ogaz, Christopher R. Jasper, Tyler R. Goodearly, and Matthew J. Young

Paratypes WFB - 3171a-3171i (n=9). data the same as holotype.

Meristics: holotype (paratypes)

Standard length: 70 (41–56 mm)

Lateral line scales: 74 (63–73). Lateral line incomplete in most; counts include 2–3 scales beyond lateral line.

Scales above lateral line: 13 (11–14)

Scales below lateral line: 9 (8–10)

Dorsal-fin rays: 8(8), counts include single unbranched ray.

Anal-fin rays: 7 (7), counts include single unbranched ray.

Pectoral-fin rays 15 (12–15), counts include unbranched rays.

Pelvic 7 (8–9), counts include unbranched rays.

Caudal-fin rays 19 (19).

Basic morphology is described below. Barbels and frenum are usually present.

Diagnosis. Same as for Western Speckled Dace, R. klamathensis . Distinguished by distribution and genomics as the Speckled Dace endemic to aquatic habitats in Sacramento River drainage basin and associated coastal drainages.

Description. Sacramento Speckled dace are identical to Klamath, Warner, and Lahontan Speckled Dace based on meristics and morphometrics. This is presumably the reason they have been undescribed for so long. The general description of Speckled Dace in Moyle (2002:161) was based on Sacramento dace, so fits the subspecies well: The Speckled Dace is a small (usually <8 cm SL, occasionally to 11 cm SL), highly variable species distinguished by a thick caudal peduncle, a small subterminal mouth, a pointed snout, and small scales (47–89 in lateral line). The origin of the dorsal fin (6–9 rays, usually 8) is well behind that of the pelvic fins. The anal fin normally has 7 rays (6–8). The pharyngeal teeth (1,4-4,1 or 2,4-4,2) are strongly hooked and have only a slight grinding surface Color is highly variable but most fish over 3 cm SL have dark speckles on the sides and back, dark blotches on the sides that often coalesce to resemble a dark lateral band, and a stripe on the head that runs through the snout. The background color on the back and sides is dusky yellow to dark olive, with the belly yellowish to whitish. The bases of the fins of both sexes turn orange to red during breeding and males often have red snouts and lips as well. Presence of maxillary barbels and a frenum is variable.

Rutter (1908:140) noted that Sacramento dace were quite variable in their characteristics and found that Sacramento dace from 12 localities (n=94) had 49–77 scales in the lateral line, 7–9 dorsal rays, and 6–8 anal rays. Cornelius (1969) using data from six localities, counted 54–82 scales on the lateral line (mean 70, n = 123); other counts: scale rows above the lateral line (12–20, mean 16, N = 124) scale rows below lateral line (10–19, mean 14, n = 121), vertebrae (34–39, mean 37, n=99), dorsal-fin rays (7–9, mean 8, n=131), anal-fin rays (5–8, mean 7, n =129). See also Table 3 .

Distribution. The Sacramento Speckled Dace is found in streams and lakes in the Goose Lake (Oregon and California) and Pit River watersheds, the Sacramento River and its tributaries, the Salinas basin, and, in the far south, San Luis Obispo Creek, Arroyo Grande, and the Santa Maria River ( Figure 3 ). It is conspicuous by its absence from the San Joaquin River watershed, although Rutter (1908) collected two small dace from the Kings River at Centerville. Collections made on Los Gatos Creek, an east-side tributary to the San Joaquin River, in 1941 contained Speckled Dace but there are no records of them since then (R. Leidy, pers. comm., 2021).

Sacramento Speckled Dace are absent naturally from the Russian River watershed and from all other coastal watersheds, except the San Lorenzo River, Salinas River, San Luis Obispo Creek and the Santa Maria River in southern California. They are also absent from Clear Lake (Lake County) and its tributaries. However, they are present in Cache Creek which flows out of Clear Lake ( Moyle 2002, unpublished data).

Zoogeography. The Sacramento basin is a large, well-defined region, isolated by the Sierra Nevada Range on the east, the Coast Range on the west, and the Cascade Range in the north. The ancestors of this highly endemic freshwater dispersant fish fauna have ancient roots in ancient lakes and rivers of the region to the east, now drained mostly by tributaries to the Snake River ( Minckley et al 1986; Moyle 2002). Speckled Dace presumably entered the region by first colonizing the Klamath Basin with other Great Basin fishes and then by expanding their population to the Sacramento-San Joaquin basin when Klamath River headwaters connected to the region via the Pit River. Dace then found it possible to colonize most of the entire basin (except where noted), reaching as far south as the Santa Maria River (via the Pajaro-Salinas River system). The Sacramento Speckled Dace thus became a member of one of the most highly endemic assemblages of freshwater dispersing fishes in the western USA. The Sacramento Speckled Dace, however, may have been a rather late addition to this fauna, which would explain its close genetic relationship with Klamath Speckled Dace.

Genetics/genomics. The Sacramento Speckled Dace is one of three lineages, defined by genomics, that make up the Western Speckled Dace, Rhinichthys klamathensis ( Smith et al. 2017; Su et al. 2022). The three lineages are also supported by Wiesenfeld et al. (2017) and Smith et al. (2017) using mtDNA and microsatellites.

Etymology. The species name honors the Achomawi people (“river people”) whose historic homelands were along the Pit River and tributaries in northeastern California, from Goose Lake to Pit River Falls, and beyond ( Dixon 1908). The Pit River is a branch of the Sacramento River that drains much of northeastern California. This region includes the Fall River system and Achjumawi Lava Springs State Park. The Speckled Dace is one of the most abundant native fishes in streams flowing through Achomawi lands. Alternate spellings include Achjumawi and Achumawi ( Dixon 1908).

The scientific names have a confusing history, starting with Jordan and Evermann (1896), who did not mention by name Speckled Dace in the Sacramento or Klamath rivers. They did include Sacramento Speckled Dace, vaguely from California, within Agosia nubila carringtoni . This taxon was first described in 1876 as Apocope carringtoni from Utah. Jordan and Evermann (1896) basically used this taxon to include miscellaneous Great Basin populations, and provisionally fish from the Lahontan Basin, as well as from various localities in southern and central California. “These California and Nevada forms may be distinct species, but if so, we are unable to define them ( Jordan and Evermann 1896:312).” Snyder (1908) followed Jordan and Evermann (1896) in using A. n. carringtoni for a grab-bag of Speckled Dace from Oregon and California. By default, carringtoni became the species epithet for Sacramento Speckled Dace as Agosia carringtoni ( Snyder 1913, 1917) and Rhinichthys osculus carringtoni ( Shapovalov and Dill 1950, Kimsey and Fisk 1960). Moyle (1976, 2002) did not provide a name for Sacramento populations. See Table 1 for other synonyms.

Conservation Status. The Sacramento Speckled Dace is widespread and abundant in the Sacramento River and tributaries, the Pit River system, Pajaro-Salinas watershed, San Luis Obispo Creek, and the Santa Maria River. It seems to have been extirpated from the San Joaquin River and tributaries although old records are scarce. The Speckled Dace is also absent from streams tributary to the San Francisco Estuary, including the Guadalupe River and tributaries, Coyote Creek, and Alameda Creek, for which there are historic records ( Leidy 2007, R.L. Leidy, pers. comm. 2021). The dace was extirpated from Coyote Creek in the 1970s (Scoppettone and Smith 1976; J.J. Smith, pers. comm. 2021) and from Alameda Creek in the early 1900s (R. Leidy, pers. com. 2021). It has been extirpated from the Pajaro River, which flows into Monterey Bay, although it is still found in the upper and middle reaches of the San Benito River, a tributary to the Pajaro (J. J. Smith, pers. comm. 2021). The historic records, though few, indicate that the Speckled Dace was extirpated from these watersheds as the result of dams, habitat change, and diversions of water, coupled with severe drought.

Figures

FIGURE 1. Top: Lahontan Speckled Dace (ca. 70 mm TL) and cover habitat in Taylor Creek, California, a tributary to Lake Tahoe. The body shape, stripe on head, and speckling are characteristic of live fish in many populations from Mexico to Canada that have been considered to be just one species, Speckled Dace (Rhinichthys osculus). Photo by T. L. Taylor, July 17, 1991. Bottom: Preserved specimen of Sacramento Speckled Dace, collected by John Otterbein Snyder from Alameda Creek, California in 1898, showing basic external anatomy. Note the presence of tiny maxillary barbels on head, an example of a distinctive characteristic of some populations. Photo by Jon Fong, California Academy of Sciences, of specimen SU 16172.

FIGURE 3. Current distribution of Rhinichthys in California and adjacent watersheds. The distributions are only approximate but based on occurrence in HUC 12 watersheds. The numbers refer to populations in the Owens Valley and Death Valley that are included in Amargosa Speckled Dace, R. nevadensis nevadensis and can be recognized as Distinct Population Segments (1) Owens Speckled Dace, (2) Oasis Valley Speckled Dace, (3) Ash Meadows Speckled Dace, and (4) Amargosa River Speckled Dace. Long Valley Speckled Dace are a distinct subspecies. Dace have been extirpated from the south San Francisco Bay-Santa Clara Valley region. See text for more specific distributional information. Information for this map was gleaned from Gesch et al. (2002), Patterson and Kelso (2021), Santos et al. (2013), US Census Bureau (2001), USGS (2004, 2013). Speckled Dace are typically present in a limited number of streams, springs and ditches within each mapped region. Map by Amber Manfree.

FIGURE 4. Holotypes of new taxa of Rhinichthys described in this paper, A. Santa Ana Speckled Dace (R. gabrieleno WFB 3498. B. Long Valley Speckled Dace (R. nevadensis caldera) WFB 5000, C. Warner Speckled Dace (R. klamathensis goyatoka) WFB 122-10-44, D. Sacramento Speckled Dace (R. klamathensis achomawi) WFB 3171.