Etheostoma erythrozonum, Switzer, John F. & Wood, Robert M., 2009

Switzer, John F. & Wood, Robert M., 2009, Etheostoma erythrozonum, a new species of darter (Teleostei: Percidae) from the Meramec River drainage, Missouri, Zootaxa 2095, pp. 1-7 : 2-7

Etheostoma erythrozonum , new species

Meramec Saddled Darter Figure 1

Holotype. USNM 391646, male, 67 mm SL, Huzzah Creek at the Reis Biological Station, 6.2 km upstream from the Route 8 bridge (37° 56.871'N; 91° 10.676'W), Crawford County, Missouri, 3 April 2003.

Paratypes. Missouri, Crawford County. USNM 391647, (3, 55– 67 mm SL), taken with holotype. JFBM 45691, (3, 51– 66 mm SL), taken with holotype. JFBM 45692, (6, 48– 71 mm SL), same locality, 1 June 2001. UAIC 15267.01, (7, 46– 71 mm SL), same locality, 1 June 2001.

Additional materials (nontypes).

Missouri: Crawford County: UAIC 15268.01 (10, 57–77) Meramec River at Scotts Ford Access, 6 April 1996. CU 34444 (12, 48–71) Courtois Creek at Walter Diggs Farm, 2 mi. downstream from Butts, 26 August 1959. Dent County: UMMZ 149516 (10, 49–64) Meramec River, 2 mi. NW of Short Bend, 23 August 1941. Franklin County: KU10141 (8, 45–54) Bourbeuse River at Noser Mill, 11 July 1963. UAIC 7938.17 (11, 50–66) Meramec River at Meramec State Park, 21 October 1987. UAIC 15269.01 (4, 47–60) Meramec River at Robertsville State Park (38° 26.13’N; 90° 49.49’W), 1 April 2000. St. Francois County: CU 63065 (10, 47–53) Big River below Route K bridge, 3 mi. east of Bonne Terre, 22 Aug 1967. Washington County: JFBM 45693 (7, 53–75) Big River at Missouri Department of Conservation Bootleg Access, 10 mi. south of Potosi (37° 48.765’N; 90° 46.332’W), 3 October 1999.

Diagnosis. Member of subgenus Poecilichthys as defined by 4–6 dark saddles on back and upper sides, saddles angled obliquely forward; breeding tubercles on males and females; in males tubercles well developed on scales of the breast, lower side anterior to the anal fin, along the anal fin, and ventral scales of the caudal peduncle, enlarged ridges along anal fin rays; in females tubercles occasionally present on ventral scales; complete lateral line; no interruptions in head canals; broadly joined branchiostegal membranes; 6 branchiostegal rays; long tubular genital papilla in the female; premaxillary frenum present; 2 anal spines.

Distinguished from other species of Poecilichthys by 4 dark saddles on back and upper sides (vs. 5 or 6 in E. kanawhae and E. osburni ), scales on breast (vs. unscaled in E. kanawhae and E. osburni ), the absence of blue on the body (vs. blue present in E. tetrazonum and E. variatum ), and prominent red-orange blotches on body (vs. small orange spots in E. euzonum ).

Most similar to E. tetrazonum but distinguished by the lack of blue-green on the body, a prominent feature of E. tetrazonum ; presence in males of a horizontal red-orange stripe extending along the lower sides from the pelvic fins to the anal fin with an irregular dorsal margin vs. dorsal stripe with a well-defined dorsal margin in E. tetrazonum ; and a series of red-orange blotches that are irregular in shape from the anal fin to the base of the caudal fin, vs. well defined vertical bars in E. tetrazonum . The spinous dorsal fin of male E. erythrozonum usually lacks the broad blue base present on E. tetrazonum ; if present, the blue is relatively inconspicuous. The anal fin of E. erythrozonum is blue-green with red-orange spots forming two horizontal rows across the fin; red-orange spots are rarely observed on the anal fins of E. tetrazonum , and never to the extent present in E. erythrozonum . The modal number of dorsal-fin spines is 13 in E. erythrozonum , 12 in E. tetrazonum ( Table 4 ). The modal number of pectoral-fin rays is 16 in E. erythrozonum , 15 in E. tetrazonum ( Table 7).

Description. Etheostoma erythrozonum is a relatively large, stout-bodied species of Etheostoma . Frequency distributions of scales, spines and fin rays given in Tables 1–8. Dorsal-fin spines (11–14, modally 13), dorsal-fin rays (12–14, modally 13), anal-fin rays (8–10, modally 9), principal caudal rays (16–18, modally 17), pectoral-fin rays (15–17, modally 16), lateral-line scales (39–55, modally 50), cheek scales absent, opercle partially scaled (0–9 scales, modally 5), breast partially to completely scaled, nape completely scaled. Both males and females of this species have four prominent dark saddles on the back and dorsal sides, with the sides angled obliquely forward. The background color is dusky in the dorsal region, lighter in the sublateral region and white on the belly. Along the sides is a series of sub-lateral dark blotches. There is a dark preorbital bar extending forward and a dark suborbital bar extending down the cheek. This species exhibits extreme sexual dimorphism in nuptial color patterns.

Lateral-line scales

39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 N ¯ E. erythrozonum 1 1 5 13 16 12 20 6 2 3 1 1 81 48.9 E. tetrazonum 1 4 4 6 14 21 15 20 21 17 20 11 5 1 160 51.1 Males are characterized by the presence of a horizontal red-orange stripe extending along the lower sides from the pelvic-fins to the anal-fin. This stripe has an irregular dorsal margin. The ventral-lateral stripes are not confluent across the belly, which is white. From the anal-fin to the base of the caudal-fin the red-orange stripe continues as a series of separate, red-orange blotches that are irregular in shape. The sides are also covered by smaller, irregularly shaped red-orange spots, and there is no blue-green on the body. The spinous dorsal-fin is dark at the base, followed by a clear band, a dusky blue band, a clear band, a red band and a clear margin. The rayed dorsal-fin generally has a dusky base and has numerous red-orange spots on the rays, forming many horizontal rows across the fin. The membranes of the rayed dorsal-fin can become very dusky in males of peak breeding condition. In general the rayed dorsal-fin lacks blue, however some specimens have a faint blue wash at the base. The anal-fin is blue with red-orange spots forming two horizontal rows across the fin. There is a blue wash on the ventral margin of the caudal-fin. Pectoral-fins are generally clear with a slight yellow hue, and a series of red-orange spots. During the breeding season the membrane between pectoral-fin rays are dusky. Pelvic-fins are blue-black, with red-orange spots in some specimens. The branchiostegal rays are broadly connected and red-orange in coloration. Nuptial tubercles are well developed on scales of the breast, lower side anterior to the anal-fin, scales along the anal-fin, ventral scales of the caudal peduncle, and enlarged ridges are present along anal-fin rays.

Females of Etheostoma erythrozonum are muted in their color pattern compared to males. The branchiostegal membranes are white with orange spots; the sides are covered with small, irregularly shaped red-orange spots; the spinous dorsal-fin is dark at the base, followed by a clear band, a dusky band, a clear band, a faint orange band, and a clear margin; the rayed dorsal-fin has a dusky stripe at the base, clear membranes, and orange spots along the rays; pectoral-fins are generally clear with a series of faint orange spots; the pelvic-fins are generally unpigmented, occasionally with faint orange spots. Nuptial tubercles are occasionally present, but poorly developed on ventral scales, and ridges are not present on anal-fin rays. The female genital papilla is a long tube.

Comparisons. Observation of male nuptial color patterns across the ranges of E. erythrozonum and E. tetrazonum revealed considerable dissimilarities. Males of E. tetrazonum are characterized by the presence of a horizontal red-orange stripe extending along the lower sides from the pelvic-fins to the anal-fin. This stripe has a well-defined dorsal margin. The ventral-lateral stripes are not confluent across the belly, which is white. Seven vertical red-orange bars are evenly spaced from the posterior extent of the horizontal red-orange stripe to the base of the caudal-fin. Often the first vertical red-orange bar is continuous with the horizontal redorange stripe. Between the vertical red-orange bars are blue-green vertical bars. A blue-green patch extends from the region just posterior to the pelvic-fin insertion up the side and around the pectoral-fin and onto the operculum and cheek. The second dorsal-fin is blue-green across the base with orange spots on the fin rays forming several horizontal rows across the fin. The anal-fin is blue-green with a clear margin and is without any orange spots in most specimens.

In contrast, males of E. erythrozonum have a horizontal red-orange stripe extending along the lower sides from the pelvic-fins to the anal-fins with an irregular dorsal margin. From the anal-fin to the base of the caudal-fin the red-orange stripe continues as a series of separate, red-orange blotches that are irregular in shape, not well defined vertical bars as in E. tetrazonum . Etheostoma erythrozonum lacks any blue-green on the body, a prominent feature of E. tetrazonum . The spinous dorsal-fin of male E. erythrozonum lacks the broad blue base present on E. tetrazonum , and if present, the blue is relatively inconspicuous. The anal-fin of E. erythrozonum is blue-green with red-orange spots forming two horizontal rows across the fin; red-orange spots are rarely observed on the anal-fins of E. tetrazonum , and never to the extent present in E. erythrozonum .

Examination of meristic data revealed two counts that differed between E. erythrozonum and E. tetrazonum . The modal number of dorsal-fin spines was 13 in E. erythrozonum , while it was 12 in E. tetrazonum ( Table 4 ). The pectoral-fin ray count differed between these species, with a modal number of 16 in E. erythrozonum and 15 in E. tetrazonum ( Table 7).

Anal-fin rays

8 9 10 N ¯ E. erythrozonum 2 70 10 82 9.1 E . tetrazonum 1 143 16 160 9.1 Pectoral-fin rays

14 15 16 17 N ¯ E. erythrozonum 29 50 2 81 15.7 E . tetrazonum 24 96 39 1 160 15.1 Opercle scales

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 N ¯ E. erythrozonum 1 2 2 10 15 27 12 5 6 2 82 4.9 E . tetrazonum 7 7 16 41 43 21 11 7 5 1 1 160 3.9 A phylogenetic analysis of cytochrome b sequence data from across the range of E. tetrazonum by Switzer & Wood (2002) recovered E. tetrazonum and the populations described herein as E. erythrozonum as two well supported, reciprocally monophyletic groups. The average uncorrected sequence divergence between populations of E. erythrozonum and E. tetrazonum was 7.2%.

Distribution. Etheostoma erythrozonum is restricted to the Meramec River drainage of Missouri ( Figure 2 ). It is widely distributed within the Meramec River drainage, known from the main channel of the Meramec River in St. Louis County and upstream into larger tributaries. It is generally absent from small headwater streams.

Conservation status. Etheostoma erythrozonum is one of the most abundant darters within its range; its conservation status is currently considered stable ( Warren et al., 2000).

Etymology. The name erythrozonum is derived from Greek: erythros, red, and zona, zone. This name is in reference to the red-orange stripe and lateral red-orange blotches characteristic of this species, and the name is in keeping with the names of the other western members of subgenus Poecilichthys , ending in –zonum. The common name, Meramec Saddled Darter, is in reference to the Meramec River drainage, the range of this species, and the prominent dorsal saddles.

Figures

FIGURE 1. Etheostoma erythrozonum (A) male 67 mm SL, holotype USNM 391646 and (B) female 64 mm SL, paratype USNM 391647. Huzzah Creek at the Reis Biological Station, 6.2 km upstream from the Route 8 bridge, Crawford County, Missouri, 3 April 2003.

FIGURE 2. Distribution of Etheostoma erythrozonum (vertical lines) and E. tetrazonum (horizontal lines) in Missouri. The type locality of E. erythrozonum is identified with a star.

Tables

TABLE 4. Dorsal-fin spine counts for Etheostoma erythrozonum and E. tetrazonum.

	Dorsal-fin spines
	10 11 12	13	14	N	¯
E. erythrozonum	1 11	61	9	82	13.0
E. tetrazonum	1 35 109	14	1	160	11.9