Pacifastacus okanaganensis Larson & Abbott & Gilmore & Helbing & Lopez & Macintosh & Stenhouse & Williams & Usio 2025, sp. nov.
Creators: name: Larson, Eric R.
name: Abbott, Cathryn L.
name: Gilmore, Scott R.
name: Helbing, Caren C.
name: Lopez, Mark Louie D.
name: Macintosh, Hugh
name: Stenhouse, Liane M.
name: Williams, Bronwyn W.
name: Usio, Nisikawa
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Astacidae
Pacifastacus
Pacifastacus okanaganensis

description: Pacifastacus okanaganensis Larson sp. nov.
urn:lsid:zoobank.org:act: F9687AA1-D8A4-485D-A0BE-78F56253E559
(Fig. 7, Table 3)
Astacus klamathensis. — Lord, 1866: 278.
Astacus Klamathensis.— Hagen, 1870: 93, 94, 98, 102, pl. III fig. 169a, b, c [all in part].
C. Klamathensis.— Hagen, 1870: 102 [erroneous combination].
A. klaymathensis.— Huxley, 1880: 223 [in part; erroneous spelling].
Astacus Klamathensis.— Faxon, 1884: 151 [in part].
Astacus klamathensis. — Faxon, 1885: 130, 131, 132 [all in part].
Astacus klamathensis. — Faxon, 1890: 634 [in part].
Astacus klamathensis. — Faxon, 1898: 665 [in part].
Potamobius (Potamobius) klamathensis (Stps.).— Ortmann, 1902: 286 [in part].
Pacifastacus klamathensis.—Bott, 1950: 24 [by implication, in part].— Miller, 1960: 130, 132, 197, 198, pl. VIII fig. 39 [all in part].
Pacifastacus leniusculus klamathensis.— Miller, 1960: 133, 146, 160, 180, 181 [all in part].
Pacifastacus leniusculus.— Hobbs, 1972: 21 [by implication].— Larson & Olden, 2011:64 [in part].
Pacifastacus leniusculus leniusculus.— Hobbs, 1972: 21 [in part].— Hobbs, 1974: 6 [in part; neither fig. 5 nor 6, p. 81 = P. okanaganensis sp. nov.].
Pacifastacus leniusculus klamathensis.— Hobbs, 1974: 22 [in part].— Larson et al., 2012: 3, 6, 12, fig. 1 [all in part].— Larson & Williams, 2015: 413, 419, 424 [in part], fig. 17.2.
Pacifastacus (Pacifastacus) leniusculus klamathensis.— Bouchard, 1978: 431 [by implication; in part].— Hobbs, 1989: 82 [in part].
Pacifastacus (Pacifastacus) leniusculus leniusculus.— Hobbs, 1989: 82 [in part].
Pacifastacus lenisculus lenisculus.— Fitzpatrick, 1983: 155 [erroneous spelling].
Pacifastacus leniusculus.— Larson et al., 2012: 2, 3, 4, 5, 6 [all in part].
Pacifastacus klamathensis.— Larson et al., 2012: 2, 3 [in part]
Okanagan group.— Larson et al., 2012: 7, 8, 10, 12 [by implication], 13, fig. 2, table 1, 2. — Larson & Williams, 2015: 419, 426, fig. 17.2.— Larson et al., 2016: 10, 12, fig. 3.
Pacifatacus leniusculus klamathensis.— Larson & Williams, 2015: 413 [erroneous spelling].
Type material. Holotype (RBCM 012-00121-003), male, Jewel Lake, British Columbia (49.1827°, -118.6000°). Allotype (RBCM-012-00121-004), female, Jewel Lake, British Columbia (49.1827°, -118.6000°).
Other material. RBCM 012-00100-001, Deep Lake, Washington (47.5878°, -119.3385°); RBCM 012-00121- 001, Jewel Lake, British Columbia (49.1827°, -118.6000°); RBCM 012-00122-011, Blueberry Creek, British Columbia (49.2593°, -117.9389°); RBCM 012-00123-001, Kettle River, British Columbia (49.1097°, -118.9792°); RBCM 012-00124-001, Idabel Lake, British Columbia (49.7404°, -119.1794°); RBCM 012-00125-001, Okanagan Lake, British Columbia (50.1802°, -119.4412°); RBCM 012-00304-001, Park Lake, Washington (47.5879°, - 119.3964°). Number of specimens by sex in Table 1.
Type locality. Jewel Lake, Jewel Lake Provincial Park, British Columbia (49.1827°, -118.6000°).
Diagnosis. Pacifastacus with rostrum bearing single pair of marginal tubercles or spines; acumen length less than 79.4% of anterior rostrum width; rostrum length more than 18.85% of TCL (Fig. 3).
Description. Body and eyes pigmented. Eyes not reduced. Rostrum deflected ventrally, base and anterior broad, margins sub-parallel, non-serrate; median carina subtle; acumen strongly converging, separated from remainder of rostrum by weak spines or tubercles; length 62% of anterior rostrum width (12%sd).Rostrum length including acumen 150% of base rostrum width (14% sd) and 21% of TCL (2% sd); anterior rostrum width 75% of posterior rostrum width (5% sd). Cephalothorax subcylindrical; postorbital ridge not terminating in spine, occasionally terminating in tubercle; TCL 203% of carapace width (9% sd); areola length 33% of TCL (1% sd), 233% of areola width (29% SD); areola width 29% of total carapace width (4% sd). Third pereopods without hook on ischium. Chelae without tubercles; palm length 87% of maximum chelae width at palm (12% sd); 36% of propodus length (10% sd); chelae height 63% of maximum chelae width at palm (3% sd). First pleopod (gonopod) of males nondescript, typical for genus. Annulus ventralis lacking, typical for genus.
Holotypic male. Body compressed dorsoventrally (Fig. 7A). Rostrum broad, deflected ventrally; margins sub-parallel with anterior width 78% of posterior width, without spines or tubercles; median carina weak (Fig. 7B). Rostrum length 110% of posterior width and 16% of TCL; acumen 34% of rostrum length. Carapace slightly wider (103%) than abdomen, maximum depth less (83%) than carapace width; TCL 27.4 mm; areola 227% longer than wide, 34% of TCL (Fig. 7B); short postorbital ridges terminating in small tubercle, carapace otherwise lacking tubercles or spines. Abdomen slightly longer than carapace (108%). Palm length 90% of palm width, palm depth 62% of palm width (all measurements and counts based on right chela; Fig. 7C). Gonopod nondescript, typical for genus (Fig. 7D, E). Epistome with semi-circular anterior lobe, lacking setae (Fig. 7F). Right antennal scale 4.9 mm long and 1.7 mm wide (Fig. 7H). Third pereopods without hook on ischium.
Allotypic female. Differing from holotype in following respects: TCL 21.7 mm; areola length 34% of TCL, 228% longer than wide; anterior rostrum width 77% of posterior rostrum width; rostrum length 132% of posterior width, 19% of TCL, acumen 32% of rostrum length; palm length 86% of palm width, palm depth 61% of palm width (all measurements and counts based on right chela). Antennal scale 3.7 mm long and 1.4 mm wide. Annulus ventralis absent (Fig. 7G).
Size. The largest individual measured at RBCM was 47.0 mm TCL.
Color. Olive brown to brick red (Fig. 8). The white mark at the joint of the dactyl and propodus in P. leniusculus is generally absent or reduced.
Etymology. From an Okanagan-Salish language place name. We propose the common name of the “Okanagan Crayfish” due to the distribution of P. okanaganensis sp. nov. throughout the Okanagan and Thompson plateaus and Okanagan Lake, British Columbia, as well as Okanogan County, Washington, and due to the Okanagan lineage terminology of Larson et al. (2012) and Larson et al. (2016).
Geographic distribution and habitat. Pacifastacus okanaganensis sp. nov. has been most often collected from relatively isolated, mid-elevation lakes in the Okanagan and Thompson plateaus of British Columbia and Washington (Fig. 6). The species has also been collected from large Okanagan Lake in British Columbia, and lakes below Dry Falls in central Washington at Sun Lakes State Park (Deep and Park lakes). The only lotic records for the species are from the Kettle River and Blueberry Creek in British Columbia. Blueberry Creek was sampled as the outlet stream immediately below Nancy Greene Lake in Nancy Greene Provincial Park. Whether the species was more prevalent in the mainstem Columbia River before invasion of F. virilis is unknown (Larson et al. 2010). Fish and Trout lakes in Washington, documented by mtDNA sequencing in Larson et al. (2012), are the only locations from past sequencing work not vouchered at RBCM (Fig. 6). The eastern range extent of the species into the upper Columbia River watershed of British Columbia, Idaho, and Montana is unknown. Pacifastacus okanaganensis sp. nov. has never been detected west of the Cascade Mountains in coastal British Columbia or Washington.
Life history notes. Life history of P. okanaganensis sp. nov. has not been studied, and berried or ovigerous individuals are not included among the RBCM vouchers. Pacifastacus okanaganensis sp. nov. life history might be anticipated to broadly resemble other congeners, as slower-growing and with lower fecundity proportional to carapace length relative to members of the family Cambaridae native to eastern North America (Momot 1984).
Conservation status. Pacifastacus okanaganensis sp. nov. could be vulnerable to displacement by invasive F. virilis, common in the mainstem Columbia River of Washington (Larson et al. 2010) and recently discovered in this watershed in British Columbia (Phillips 2024). Pacifastacus leniusculus could also threaten P. okanaganensis sp. nov. with displacement, as it has impacted congeners in California (Bouchard 1977; Light et al. 1995; U.S. Fish and Wildlife Service 1988). Pacifastacus okanaganensis sp. nov. is known from more locations than P. malheurensis sp. nov., and many of these locations are relatively isolated, mid-elevation lakes that may be difficult for other crayfish species to spread into without the assistance of human introductions. As the magnitude and timing of displacement of P. okanaganensis sp. nov. by either F. virilis or P. leniusculus in the Columbia River watershed is unknown, we recommend a global IUCN conservation status of data deficient (IUCN 2012). We recommend rankings of Imperiled in both British Columbia and Washington because only four or five occurrences of P. okanaganensis sp. nov. are known from each of these jurisdictions (Fig. 6).
Crayfish associates. Pacifastacus okanaganensis sp. nov. was not collected in sympatry with other crayfish species by Larson et al. (2012) or Larson et al. (2016). Both F. virilis and P. leniusculus occur in the vicinity of P. okanaganensis sp. nov. populations, including in the mainstem Columbia River.
Relationships and comparisons. Pacifastacus okanaganensis sp. nov. is morphologically similar to P. malheurensis sp. nov. and P. l. klamathensis from coastal, southwestern Oregon and northwestern California. Pacifastacus okanaganensis sp. nov. generally has an acumen length less than 79.4% of anterior rostrum width, whereas P. leniusculus generally has an acumen length greater than 79.4% of anterior rostrum width (Fig. 3). Pacifastacus okanaganensis sp. nov. generally has a rostrum length greater than 18.85% of TCL, whereas P. malheurensis sp. nov. generally has a rostrum length less than 18.85% of TCL (Fig. 3). Pacifastacus l. leniusculus in particular are easy to differentiate from P. okanaganensis sp. nov. by the long, spiny rostrum and chelae with short, convex palms (Hobbs 1972). Pacifastacus okanaganensis sp. nov. has not been collected in sympatry with P. malheurensis sp. nov. or coastally distributed P. l. klamathensis and may be also differentiated by geographic range.
description: Published as part of Larson, Eric R., Abbott, Cathryn L., Gilmore, Scott R., Helbing, Caren C., Lopez, Mark Louie D., Macintosh, Hugh, Stenhouse, Liane M., Williams, Bronwyn W. & Usio, Nisikawa, 2025, Genome skimming supports two new crayfish species from the genus Pacifastacus Bott, 1950 (Decapoda: Astacidae), pp. 501-521 in Zootaxa 5632 (3) on pages 514-517, DOI: 10.11646/zootaxa.5632.3.4, http://zenodo.org/record/15372563