Etheostoma percnurum Jenkins, 1994

Blanton, Rebecca E. & Jenkins, Robert E., 2008, Three new darter species of the Etheostoma percnurum species complex (Percidae, subgenus Catonotus) from the Tennessee and Cumberland river drainages, Zootaxa 1963 (1), pp. 1-24 : 8-15

Etheostoma percnurum Jenkins

Duskytail Darter

( Fig. 4a )

Holotype. UMMZ 220237 , male, 37.6 mm SL, Copper Creek just below mouth of Obeys Creek , 5.1 air km NNE center of Gate City , Scott County, Virginia, 19 May 1971, R. Jenkins, N. Burkhead, and M. Kuhl.

Paratypes. Tennessee River drainage— Clinch River system

Virginia: Scott County: UMMZ 220238 (45; 23–45 mm SL), taken with holotype ; INHS 93045 (10), taken with holotype .

Additional Material (nontypes).

Tennessee River drainage— Clinch River system

Virginia: Scott Co.: Clinch River: UF 172554 (0, 1, 0) ; Copper Creek : CU 62842 (1, 0, 1); CU 63459 (10, 7, 8) ; NCSM 49832 (3, 2, 3) ; OSM 34604 (0, 2, 0) ; RC REJ-365 (1, 0, 0); RC REJ-386 (1, 0, 1); RC REJ- 397 (2, 0, 2); RC REJ-431 (2, 0, 0); RC REJ-501 (2, 0, 2); RC REJ-521 (2, 0, 3); TU 69270 (4, 0, 4) ; TU 70413 (1, 1, 1) ; TU 71976 (10, 0, 10) ; TU 200485 (1, 1, 1) ; TU 200486 (1, 1, 1) ; TU 200487 (4, 3, 4) ; TU 200488 (2, 2, 2) ; TU 200489 (5, 7, 5) ; TU 200490 (10, 7, 10) ; TU 200491 (4, 2, 4) ; UF 43659 (1, 0, 1) ; UF 172553 (10, 2, 10) ; USNM 393570 (5, 0, 5) ; USNM 393572 (10, 0, 10) ; UT 91.1927 (1, 0, 1).

Diagnosis. Etheostoma percnurum is distinguished from all other members of the E. percnurum species complex by the following combination of characteristics: fewer pored lateral-line scales (22 vs. 26 or higher); lower percentage of body area along first dorsal-fin base covered by scales (20% vs. 60% or higher); wider, dusky, distal band on caudal fin (range = 17–25% of fin length vs. 12–18% in others) and pectoral fin (range =

27–32% of length vs. 14–21% in others) of nuptial males; absence of tessellations or bands in medial portion of caudal fin of nuptial males (vs. presence of tessellations or bands); fewer scales around caudal peduncle (23 vs. 24 or 25); more caudal-fin rays (18 vs. 15 or 16); longer pectoral fin (=252 vs. =248 or less); and higher anal fin (=127 vs. =123 or less). Further distinguished from E. marmorpinnum and E sitikuense by absence of marbling in second dorsal fin (medial fin region dusky overall vs. strongly or diffusely marbled); and wider distal band on second dorsal fin (23–25% of fin height vs. 14–21%) and anal fin (49–58% of fin height vs. 29–39%); and from E. marmorpinnum by less belly area scaled (0% vs. 60-80%). Means of other measurements were also informative for distinguishing E. percnurum ( Table 9).

Description. Meristic counts are given in Tables 1–7 or provided below. Scales below lateral line 7–11 (8, =8.4±0.8); scales above lateral line 5–8 (6, =6.5±0.6); caudal peduncle scales below lateral line 10–14 (11, =11.3±0.9); caudal peduncle scales above lateral line 9–12 (10, =10.1±0.7). Opercle, breast, and nape devoid of scales. Branchiostegal rays six; gill membranes narrowly to moderately joined. First dorsal-fin spines 6–8 (7, =7.0±0.3); second dorsal-fin rays 10–13 (11, =11.6±0.6); pectoral-fin rays 12–14 (13,

=12.9±0.5); anal spines 2–3 (2, =2.0±0.1); anal-fin rays 6–8 (7, =7.3±0.5); caudal-fin rays 15–18 (18,

=17.4±0.7). Preopercular-mandibular pores 10 (10, =10.0±0.0); infraorbital pores usually 6, rarely 5 or 7 (6, =6.0±0.4); anterior infraorbital pores usually 4, rarely 5 (4, =4.1±0.3); posterior infraorbital pores usually 2, rarely 1 (2, =1.9±0.2); supraorbital pores usually 4, rarely 5 (4, =4.1±0.2); supratemporal pores usually 4, rarely 3 (4, =4.0±0.2); left supratemporal pores usually 2, rarely 1 (2, =2.0±0.2); right supratemporal pores 2 (2, =2.0±0.0).

Measurements for males (nuptial and non-nuptial) are in Table 9. Females (n=22): SL 32.1–43.9 (=36.6±3.1); GW 60–100 (=81±11); IOW 40–60 (=49±8); HW 100–130 (=116±10); HL 280–340 (=318±14); P1L 230–270 (=253±11); P2L 190–230 (=206±11); D1H 80–120 (=104±11); D1L 170–210 (=184±12); D2H 130–160 (=147±9); AFH 100–140 (=125±10); CFL 180–210 (=205±9); BW 50–90 (=67±11); H1–H2 100–130 (=112±7); H1–H3 200–240 (=220±10); H1–B4 350–380 (=365±10); H1–H5 110–160 (=128±12); H1–B6 290–360 (=315±21); H2–H5 110–140 (=119±9); H3–B6 150–190 (=171±12); B4–B6 or BD1 130–200 (=166±15); B4–B7 230–280 (=250±15); B4–B8 290–340 (=313±13); B6–B7 270–390 (=343±26); B6–B8 290–370 (=318±19); B7–B8 or BD2 130–170 (=151±10); B7–B9 or D2L 190–240 (=211±15); B7–B10 190–230 (=213±11); B8–B9 200–270 (=227±14); B8–B10 or AFL 100–160 (=143±15); B9–10 100–130 (=113±8); B9–C11 150–190 (=170±10); and B10–C11 200–230 (=215±11).

In-life and preserved pigmentation and coloration were described by Jenkins (1994). For all individuals examined: number of transverse bars for males 10–14 (13, =12.3±1.0), for females 10–15 (12, =12.4±1.2); number of dorsal saddles for males 6–8 (7, =7.1±0.3), for females 5–8 (7, =7.0±0.4); number of caudal-fin tessellations along medial ray for males 3–6 (3, =3.8±1.3), for females 3–10 (7, =6.5±1.7); tessellations not forming bands; and caudal peduncle with no spots, or with 1 or 2 light smudges or spots. For nuptial males: wide, dusky, distal band on caudal (range = 17–25% of fin length), anal (range = 49–58% of fin height), pectoral (range = 28–32% of fin length), and second dorsal fin (23–25% of fin height). Medial portion of second dorsal fin and caudal fin without tessellations or marbling pattern in nuptial males; medial regions overall dusky.

Distribution. The Duskytail Darter occupies Copper Creek of the Clinch River (Tennessee River drainage), Scott County, Tennessee. In Copper Creek from its mouth upstream for approximately 29 river kilometers (rkm); one specimen taken in 1980 in the mainstem Clinch River at Speers Ferry, 1 rkm below mouth of Copper Creek. The species varies from rare to common at different sites within Copper Creek (CFI pers. comm.). Post–1980 surveys of the Clinch River (by CFI personnel) have not found additional specimens of E. percnurum .

Ecology. Etheostoma percnurum occupies the lower main channel of Copper Creek, which is a clear, warm, moderate-gradient, intermontane stream in the Ridge and Valley Province of Virginia. Adults occur primarily in pools, and much less frequently in swift runs, and are associated with relatively clean gravel, cobble, and boulders. The range of habitats includes slack water, detritus, slightly silted stones, and bedrock (Jenkins 1994). In Copper Creek, E. percnurum is syntopic with the widespread E. flabellare (Jenkins 1994: map 189). Etheostoma flabellare is uncommon to common in the middle and upper portions of mainstem Copper Creek and some of its tributaries whereas, E. percnurum occupies lower reaches of the mainstem and has not been found in tributaries (Jenkins 1994). Areas of syntopy are in the mid to upstream distributional limits of E. percnurum (Jenkins 1994) . Hybrids between the two species have not been observed.

Conservation Status. Etheostoma percnurum is recognized as a federally endangered species. Impoundments, siltation associated with poor land-use practices, coal mining, and logging have contributed to its decline ( Burkhead & Jenkins 1991). Identification and correction of sources of erosion and other pollutants to Copper Creek are strongly recommended.

Historically, the species has been regarded as rare ( Burkhead & Jenkins 1991), and recent snorkel surveys (by CFI) of Copper Creek and nearby portions of the mainstem Clinch River have confirmed that E. percnurum is restricted to Copper Creek where it varies from rare to common at sites in the lower reaches of this stream. A recovery plan was outlined by the United States Fish and Wildlife Service soon after the original description of E. percnurum ( Biggins & Shute 1994) ; however, this plan was designed under a different concept of diversity. Etheostoma percnurum was thought to consist of four extant populations occurring in three locations in the Tennessee drainage and one in the Cumberland drainage. Our study has found that E. percnurum is actually restricted to Copper Creek. Other populations represent distinct species. Thus the number of wild populations has been reduced from four to one, and a new plan that includes continued monitoring of habitat quality and the population status in Copper Creek is much needed. Propagation may help ensure the survival of the species and translocation outside Copper Creek to known extirpated portions of its range, such as the mainstem Clinch River, may decrease the chance of extinction. Translocation to other areas outside the known historical range of the species is strongly discouraged due to potential negative effects to other species.

Comments. Due to some confusion of the year of publication for the Freshwater Fishes of Virginia we clarify that the official date of publication for the original description of E. percnurum (Jenkins in Jenkins and Burkhead 1994) is 21 April 1994 as indicated by Burr (1995; Jenkins’s information).

Figures

FIGURE 4. Nuptial male pigmentation patterns for (A) Etheostoma percnurum, Copper Creek, VA, (B) E. marmorpinnum, Little River–Tennessee drainage, (C) E. sitikuense, Citico Creek, Abrams Creek, and Tellico River–Little Tennessee system, and (D) E. lemniscatum, Big South Fork–Cumberland drainage. Illustrations by J. Sipiorski, 2008.