Hesperoleucus venustus Snyder 1913
Creators: name: Baumsteiger, Jason
name: Moyle, Peter B.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Cypriniformes
Cyprinidae
Hesperoleucus
Hesperoleucus venustus

description: Hesperoleucus venustus Snyder, 1913
Coastal Roach
Holotype: USNM 74476. Originally described from Coyote Creek, Santa Clara Co., CA. Paratypes: CAS-SU 22492, 24282; USNM 75335.
Snyder (1913) originally split this species into three species: H. navarroensis (from the Navarro River), H. venustus (from the Russian River), and H. subditus (Monterey region). These populations were later considered to be subspecies within the single species CA Roach, as suggested by the unpublished study of Murphy (1948). Aguilar & Jones (2009) did not find strong support for these species or subspecies with their mtDNA analysis although their microsatellite analysis found some structure among regions. As mentioned above, Baumsteiger et al. (2017) found clear evidence for populations in all coastal draining watersheds belonging to a single species. Subspecies were also detected but more broadly distributed than previously thought. Watersheds extending from the Russian River north to the Eel River (excluding the Gualala River) clustered as one subspecies and watersheds south of the Russian River (Tomales Bay to the Monterey region) clustered as a second.
Description. Based on previous morphological work, the Coastal Roach species has a mixture of characters (Table 1). For a cyprinid, the head is large and conical, the tail deeply forked, the eyes large, and the mouth subterminal, slanting at a downward angle. However, the body can be stout or slender, the snout short or more pointed, the caudal peduncle narrow or thick, and the fins small and rounded or long and narrow. Individuals are typically less than 120 mm total length. The dorsal fin is short (7–10 rays) and positioned behind the insertion point of the pelvic fin. The anal fin has 6–9 rays. Pharyngeal teeth (0,5—4,0) have curved tips which overhang grinding surfaces of moderate size. Gill rakers number 8–11. The scales are small, numbering 47–63 along the lateral line and 32–38 before the dorsal fin. Individuals are usually dark on the upper half of their bodies, ranging from a shadowy gray to a steel blue, while the lower half of the body is much lighter, usually a dull white/silver color. A light lateral stripe approximately two scales wide extends from upper edge of the gill opening to the base of tail and entirely above the lateral line. Below this line is a somewhat wider dark stripe and then several narrower and very distinct dark stripes which grow lighter ventrally.
Distribution. Coastal Roach are restricted to coastal watersheds, largely west of the coastal mountain range. The northernmost native population is in the Navarro River, although introduced Coastal Roach exist in the Eel River. Excluding the Gualala River (see below), watersheds south of the Navarro River do not support any Roach populations until the Russian River. Populations are then found intermittently from the Russian River south to the Tomales Bay region. Scattered Coastal Roach are found in streams around San Francisco Bay but are once again absent from coastal watersheds to the south until the Salinas and Pajaro river watersheds of the Monterey region. The population in Soquel Creek (Santa Cruz Co.) is probably introduced from the Salinas River, while the origin of the population in the Cuyuma River (San Luis Obispo and Santa Barbara counties) is uncertain but may be native (Moyle 2002). Coastal Roach are widespread in the Eel River, from an introduction in the early1970s. This introduction was noted by Moyle (2002) and Jones (2002) and is now confirmed by Baumsteiger et al. (2017) and A. Kinziger (pers. comm. 2017). Studies show that Eel River fish originated from the Russian River mainstem and not the recently connected East Fork (via the Potter Valley Project - Power et al. 2015).
Status. Due to its wide distribution throughout northern California coastal drainages, the species appears to be in little danger of extinction. However, subspecies or distinct population segments (see below) may be at risk within their particular watershed(s).
description: Published as part of Baumsteiger, Jason & Moyle, Peter B., 2019, A reappraisal of the California Roach / Hitch (Cypriniformes, Cyprinidae, Hesperoleucus / Lavinia) species complex, pp. 221-240 in Zootaxa 4543 (2) on pages 230-231, DOI: 10.11646/zootaxa.4543.2.3, http://zenodo.org/record/2617771