Etheostoma marmorpinnum Blanton and Jenkins, 2008

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 : 15-17

Etheostoma marmorpinnum Blanton and Jenkins , new species

Marbled Darter

( Fig. 4b )

Holotype. UF 172572, male, 37.8 mm SL, Little River just below TN Highway 33 bridge, Blount County, Tennessee, 26 April 1984, S. Layman and J. Shute.

Paratypes. Tennessee River drainage— Little River system

Tennessee: Blount County: ANSP 189238 (2), Little River , just downstream of TN Highway 33 bridge in slabrock pool above riffle , 6 May 1985, S. R. Layman; INHS 102268 (2), Little River at TN Highway 33 bridge near Rockford , 26 May 1985, R. D. Suttkus and D. A. Etnier; NCSM 49701 (3; 37.5–40.6 mm SL), Little River at TN Highway 33, 7.2 air km NNE center of Maryville (35.8195° N; 83.9381° W) , 11 November 1974, W. C. Starnes, D. A. Etnier, G. Boronow, M. Hughes, G. Schuster, and Schraw; TU 140998 (2), same locality as INHS 102268; UF 172573 (3; 28.8–36.5 mm SL), taken with holotype; USNM 394525 (2), same locality as INHS 102268; UT 91.2615 (1), same locality as ANSP 189238.

Additional material (nontypes).

Tennessee River drainage— Little River system

Tennessee: Blount County: INHS 82442 (6, 7, 3) ; TU 140998 (6, 5, 6) ; UF 191714 (1, 0, 0) ; UT 91.1035 (13, 0, 13) ; UT 91.1916 (0, 1, 0) ; UT 91.2615 (3, 3, 3) ; UT 91.2675 (3, 3, 3) ; UT 91.2722 (0, 5, 0) ; UT 91.2723 (0, 6, 0) ; UT 91.2724 (0, 4, 0) ; UT 91.2725 (0, 1, 0) ; UT 91.584 (2, 2, 2) ; UT 91.781 (2, 0, 2).

Tennessee River drainage— South Fork Holston River system

Tennessee: Sullivan Co.: South Fork Holston River: UMMZ 197681 (1, 1, 0)

Diagnosis. Etheostoma marmorpinnum is distinguished from all other members of the species complex by higher percentage of belly covered by scales (60–80% vs. 10% or less); higher percentage of body area along the first dorsal-fin base covered with scales (100% vs. 70% or less); dark distinct marbling in second dorsal fin of nuptial males (vs. lighter diffuse marbling or marbling absent); narrower band width for caudalfin (range = 12–15% of fin length vs. 15–25%) and anal-fin (range = 29–33% vs. 33–58%); more scales around caudal peduncle (25 vs. 23 or 24); and higher first dorsal fin (D1H, =117 vs. 105 or less). The species is further distinguished from E. percnurum by fewer caudal fin rays (15 vs. 18); narrower distal band on pectoral fin (range = 17–20% vs. 27–32% of fin length) and second dorsal fin (14–21% vs. 23–25% of fin height); and by prominent tessellation of medial region of caudal fin of nuptial males (vs. uniformly dusky). Further distinguished from E percnurum and E. sitikuense by an intermediate number of pored lateral-line scales (27 vs. 22 or 33 respectively). Means of other measurements were also informative in distinguishing E. marmorpinnum from other members of the complex ( Table 9).

Description. Tables 1–7 provide meristic counts for most variables. Scales below lateral line 8–10 (8, 9, =8.9±0.8); scales above lateral line 6–9 (7, =7.1±0.5); caudal peduncle scales below lateral line 11–14 (12, =11.9±0.8); caudal peduncle scales above lateral line 8–12 (11, =10.4±1.1). Cheek, opercle, and breast devoid of scales; nape usually devoid of scales, rarely with 5% scale coverage. Branchiostegal rays six; gill membranes narrowly to moderately joined. First dorsal fin spines 6–7, (7, =6.7±0.5); second dorsal fin rays 11–13 (12, =11.8±0.3); pectoral fin rays 12–13 (13, =12.8±0.4); anal spines 2; anal rays 6–8 (7, =7.3±0.5). Preopercular-mandibular pores 10 (10.0, =10±0.0); infraorbital pores usually 6, rarely 5 or 7 (6, =6.0±0.3); anterior infraorbital pores 4 (4, =4.0±0.0); posterior infraorbital pores usually 2, rarely 1 or 3 (2, =2.0±0.3); supraorbital pores usually 4, rarely 5 or 6 (4, =4.0±0.4); supratemporal pores usually 4, rarely 5 (4, =4.0±0.2); left supratemporal pores usually 2, rarely 3 (2, =2.0±0.2); right supratemporal pores 2 (2, =2.0±0.0).

Measurements for males (nuptial and non-nuptial) and females are presented separately; male measurements are presented in Table 9. Females (n=19): SL 27.7–44.3 (=35.4±4.5); GW 70–100 (=86±9); IOW 30–60 (=45±7); HW 100–140 (=124±10); HL 300–330 (=321±10); P1L 220–290 (=254±18); P2L 180–220 (=203±13); D1H 90–140 (=119±14); D1L 160–230 (=198±19); D2H 120–170 (=146±13); AFH 100–150 (=123±14); CFL 190–250 (=221±16); BW 50–80 (=67±8); H1–H2 100–130 (=114±8); H1–H3 190–240 (=221±11); H1–B4 340–390 (=368±13); H1–H5 120–150 (=131±8); H1–B6 270–340 (=309±18); H2–H5 110–130 (=119±7); H3–B6 150–190 (=174±11); B4–B6 or BD1 150–210 (=175±16); B4–B7 240–300 (=266±15); B4–B8 290–350 (=321±14); B6–B7 320–390 (=365±18); B6–B8 290–360 (=327±19); B7–B8 or BD2 130–170 (=150±9); B7–B9 or D2L 180–230 (=217±14); B7–B10 190–220 (=206±10); B8–B9 220–270 (=243±15); B8–B10 or AFL 120–170 (=143±14); B9–10 110–150 (=126±10); B9–C11 130–190 (=158±15); and B10–C11 200–250 (=216±14).

Body color and general pigmentation of live and preserved individuals similar to that described for E. percnurum by Jenkins (1994). However, nuptial males of E. marmorpinnum with strongly marbled second dorsal fins and heavily tessellated caudal fins; tessellations on distal half of caudal fin often form wavy bands; narrower dusky distal bands on pectoral (range = 17–20% of fin length) second dorsal (range = 14–21% of fin height), caudal (range = 12–15% of fin length), and anal fins (range = 29–33% of fin height). For all individuals: number of transverse bars for males rarely too poorly developed to count (0), usually 11–15 (13, =10.7±4.8), for females 11–14 (12 and 13, =12.6±1.0); number of dorsal saddles for males 7–8 (7, =7.1±0.2), for females 7–8 (7, =7.1±0.4); number of rows of caudal-fin tessellations along medial ray for males 4–8 (7, =6.2±1.2), for females 4–7 (4, =5.2±1.2); and caudal peduncle with 1 caudal spot, 2 diffuse spots, or no obvious spots.

Distribution. Etheostoma marmorpinnum occurs in lower Little River (Tennessee drainage), Blount County, Tennessee, from US Hwy 411 downstream to TN Hwy 33, but is generally rare in the upstream reaches around US Hwy 411 ( Layman 1991). The species does not appear to be continuously distributed throughout this 14.5 km reach. The stronghold is just upstream of the backwaters of Fort Loudoun Reservoir around the US Hwy 33 bridge ( Layman 1991). Also known from a single specimen from the South Fork Holston River in Sullivan County, Tennessee, collected in 1947, three years before construction of the South Fork Holston Dam was completed. The capture site was 0.6 rkm above the dam, whose tailwater has long been and continues to be cold-water. The species is now extirpated from the Holston River.

Ecology. The Little River has its headwaters in the Great Smoky Mountain National Park, within the Blue Ridge Province of Tennessee, and flows north through the Ridge and Valley Province where it enters Fort Loudon Reservoir of the Tennessee River. The reach occupied by E. marmorpinnum is characterized by moderate gradient with riffles, runs, and long pools. The species is primarily associated with pools and moderate runs about 0.3–1.2 m deep with clean pebbles, cobble, and small boulders ( Layman 1991). Etheostoma marmopinnum was syntopic with E. flabellare in the South Fork Holston River; the one specimen from the South Fork Holston was collected with two E. flabellare . The species is not known to overlap geographically with any other species of Catonotus in the Little River. Etheostoma flabellare was thought to have been extirpated from the Little River until recent populations were discovered by CFI personnel in Cane and Hesse Creek inside Great Smoky Mountain National Park (P. Rakes, pers. comm.). Localities in these streams are well upstream of their confluence with the Little River and well upstream of known E. marmorpinnum sites in the Little River proper. The most common darters occurring with E. marmorpinnum in the Little River include Nothonotus rufilineatus and E. simoterum . Layman (1991) provided detailed information on the life history and general ecology of the Marbled Darter.

Conservation Status. Layman (1991) suggested that the range of E. marmorpinnum had been compressed by impoundment of the lower 12.5 km of the Little River. Although no future impoundments are planned, the habitat within the reach of river where E. marmorpinnum occurs is threatened by siltation, municipal water withdrawal, toxic spills, and habitat degradation associated with poor agriculture practices and bridge construction and maintenance ( Layman 1991). The South Fork Holston River population was extirpated by inundation of habitat by the South Holston Reservoir and by cold tailwaters ( Jenkins & Burkhead 1975). Federal protection and regular monitoring of the species status and habitat quality are needed due to the current federal status as E. percnurum , its extremely limited distribution consisting of one extant population within the Little River, evidence for past extirpations, and ongoing threats to larger river habitats. A new recovery plan that incorporates these goals and includes plans to alleviate or remove ongoing threats to the limited habitat of this species is greatly needed. Efforts to bolster numbers in upstream reaches and generate a more continuous population throughout the documented reach in the Little River should be a priority. The species has benefited from past propagation efforts (conducted by CFI); captive propagation and re-introductions that utilized individuals from the Little River as stocks have helped bolster the number of reproducing individuals in the Little River. Continued propagation efforts that utilize Little River stock and focus on capturing genetic diversity in the species would be worthwhile to its long-term survival. Translocation outside Little River to known extirpated portions of its range, such as the South Fork Holston River, may further decrease the chance of extinction. Translocation outside of the species known native range is not recommended due to the potential negative impacts to other species.

Etymology. The name marmorpinnum comes from ‘marmor’ which means marbled and ‘pinna’ for fin and refers to the distinct marbled pattern of the second dorsal fin of nuptial males, as does the common name Marbled Darter.

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.