Etheostoma rupestre piersoni, Hilburn, Janosik, and Johnston, 2023

Hilburn, Bryson G., Janosik, Alexis M. & Johnston, Carol E., 2023, Incipient speciation in allopatric Etheostoma rupestre (Percidae: Etheostomatinae) lineages, with the description of three new subspecies, Zootaxa 5343 (2), pp. 151-172 : 164-167

Etheostoma rupestre piersoni, Hilburn, Janosik, and Johnston , New Subspecies Shamrock Darter

Figure 8B , Tables 1–11

Etheostoma cf. rupestre — Near et al. 201l: 568, 578, Tbl 1., Fig. 3 (recognition as a distinct lineage, termed Central Rock Darter).

Holotype. Alabama. Dallas / Wilcox Co., USNM 398677 , 61 mm SL, Chilatchee Creek , Hwy 5, 32.2359°, - 87.4091°, 26 March 2010, C. E. Johnston, A. M. Janosik, D. E. Holt and T. H. Haley.

Paratopotypes. USNM 398678 , (2, 43–46) mm SL, same locality, 32.2359°, -87.4091°, 26 March 2010, C. E. Johnston, A. M. Janosik, D. E. Holt and T. H. Haley .

Paratypes. Alabama and Cahaba River drainages : Alabama. Bibb Co., AUM 39178 , Cahaba River , 6.2 airmi NE of Centreville, Hwy 27 (5, 47–55), 23–24 October 1978 , no lat/long available; AUM 38753 , 0.6 miles downstream of the Harrisburg Bridge, at the first gravel island (14, 43–55), 6 November 1983 32.8545°,-87.2001°; AUM 2516 , 13.4 km N of Centerville on Highway 27 (2, 46–51), 13 May 1969 , 33.0636°, -87.1308°; AUM 5880 , 10.0 air km NE of Centerville on Highway 27 (21, 40–51), 21 November 1971 , 33.0394°, -87.1308°. AUM 18172 , Schultz Creek , 6.3 air km NNW of Centerville on Highway 219 (2, 30–48), 08 September 1978 , 33.0021°, -87.1483°. Butler Co., AUM 68107 , Cedar Creek, at Cedar Creek Plantation, 13 km NW of Greenville (1, 64), 13 October 2016 , 31.90968º, -86.71909º. AUM 74489 , Caffee Creek, riffle near Griffin Town Road (5, 46–58), 22 March 2022 , 33.12001º, -87.10619º. Dallas Co., AUM 7481 , Mush Creek , 4.8 air km S of Sardis on Highway 41 (2, 46–46), 03 April 1972 , 32.2444°, -86.9928°; AUM 7653 , 4.8 air km S of Sardis on Highway 41 (4, 34–51), 11 July 1972 , 32.2444°, -86.9928°; AUM 7813 , 4.8 air km S of Sardis on Highway 41 (14, 35–47), 17 October 1972 , 32.2444°, -86.9928°. Jefferson Co., AUM 47076 , Cahaba River , Grant’s Mill, downstream of Grant’s Mill Road bridge (1, 50), 5 October 2006 , 33.5110º, -86.6584º; AUM 49331 , Mill Dam site of Grant’s Mill , 1 mi SE of Moore Corner, AL (2, 47–51), 6 June 2007 , 33.5089º, -86.6436º; AUM 18694 , 11.1 air km WSW of Leeds on Highway 143 (5, 35–46), 28 March 1979 , 33.6604°, -86.5894°. Monroe Co., AUM 15507 , Big Flat Creek , 12.9 air km NW of Monroeville on Highway 14 (24, 34–54), 16 October 1977 , 31.6078°, -87.415°. USNM 199547 , Unnamed creek, tributary of Limestone Creek between Monroeville and Mexia (1, 47), 27 November 1962 , 31.5148°, -87.3559°. Monroe Co., AUM 48923 , Big Flat Creek , downstream site of Rikard’s Mill, 1 mile NNW of Fountain (2, 49–51), 22 July 2007 , 31.6084º, -87.4143º. Shelby Co., AUM 5699 , Cahaba River , 4.2 air km N of Marvel (1, 49), 16 May 1971 , 33.1867°, -86.9997°; AUM 56142 , 2.5 airmi WSW of Helena, Hwy 52 (1, 57), 5 December 1978 , 33.2846º, -86.8827º; AUM 6660 , at river mile 3.4 on J Foshee’s Cahaba Section 8 map (1, 53), 26 September 1981 , 33.2495º, -86.9370º; AUM 65819 , at river mile 1.5 on J. Foshee’s Cahaba Section 5 map (2, 44–57), 07 November 1981 33.4037º, -86.7572º; AUM 41174 , at Booth Ford , 4.5 airmi N of Marvel, Hwy 251 (2, 57–61), 6 October 1978 , no lat/long available; AUM 66613 , at river mile 5.0 on J. Foshee’s Cahaba Section 8 map (1, 48), 26 September 1981 , 33.2360º, -86.9430º; AUM 66657 , at river mile 4.0 on J. Foshee’s Cahaba Section 6 map (1, 46), 24 October 1981 , 33.3289º, -86.8441º.

Diagnosis. While there is considerable overlap among all traits measured rendering individuals undiagnosable, populations can be diagnosed. Populations of E. r. piersoni differ from E. r. rupestre by possessing modally six scales above the lateral line (as opposed to five in E. r. rupestre ) ( Table 2 ), by possessing a higher range of lateral line scales than populations of E. r. rupestre (49–63 in E. r. piersoni vs. usually 45–59 in E. r. rupestre ) ( Table 1 ), by having a much narrower range of nape squamation (>80% scaled in E. r. piersoni vs. 0–100% scaled in E. r. rupestre ) ( Table 7 ), and by having a higher number of lateral blotches (5–9 in E. r. piersoni vs. 3–8 in E. r. rupestre ) ( Table 9 ). Populations of E. r. piersoni can be distinguished from populations of E. r. uphapeense by possessing a lower range and mean of blotches that tend to be slightly more diffuse (5–9 distinct blotches in E. r. piersoni vs. 7–9 in E. r. uphapeense ) ( Table 9 ). E. r. piersoni and E. r. uphapeense can be further distinguished with genetics (see Janosik et al. 2023).

Description. Populations of E. r. piersoni possess the following traits: lateral line scales 49–62 (modally 54–60) ( Table 1 ), scales above the lateral line 5–7 (modally 6) ( Table 2 ), scales below the lateral line 6–11 (modally 8–9) ( Table 3 ), scales around the caudal peduncle 18–23 (modally 19–21) ( Table 4), dorsal spines X–XIII (modally XI–XII) ( Table 5 ), dorsal-fin rays 10–13 (modally 11–12) ( Table 6), Nape squamation 80–100% (mean 92–96%) ( Table 7 ), belly squamation 40–90% (mean 58–60%) ( Table 8), distinct lateral blotches 5–9 (mean 7.0) ( Table 9 ), distance between lateral blotches 2.8–6.6% of SL (mean 4.6%), average lateral blotch width 4.6–8.2% of SL (mean 6.2%), average dorsal saddle width 6.6–8.8% of SL (mean 7.9%) ( Table 10 ), male distal band in first dorsal fin 24.9–51.1% of fin depth (mean 39.6%), total first dorsal pigment 49.2–78.0% of fin depth (mean 64.0%) ( Table 11 ), nuptial coloration ranging from light blue to dark green.

Distribution. Etheostoma rupestre piersoni is endemic to the Alabama and Cahaba watersheds of central Alabama ( Fig. 2 ). It is allopatric to E. r. rupestre and E. r. uphapeense .

Etymology. Named in honor of J. Malcom Pierson, an ichthyologist who made outstanding contributions to the study of Alabama’s ichthyofauna. Shamrock Darter refers to the nuptial color and pattern as it resembles that of Shamrock leaves. The common name serves as a double entendre for a derivation of the original Rock Darter (“ sham-” (false derivative) “- rock” (Rock Darter)).

Figures

FIGURE 2. Locations of museum material examined that possessed lat/long coordinates. Dark grey background shading indicates the boundaries of the Mobile Basin and colored shading indicates geographic ranges of each subspecies within the Mobile Basin to which Etheostoma rupestre is endemic. Populations delimited as E. r. rupestre in the current study but for which some taxonomic uncertainty remains are also indicated.

FIGURE 3. Locations of landmarks used in geometric morphometric analysis on specimens of Etheostoma rupestre (1: nare, 2: nape, 3: first dorsal-fin origin, 4: 9th dorsal spine insertion, 5: second dorsal-fin origin, 6: 7th dorsal ray insertion, 7: posterior insertion of dorsal fin, 8: caudal fin insertion on dorsum, 9: center edge of hypural plate, 10: caudal fin insertion on ventrum, 11: posterior insertion of anal fin, 12: 5th anal fin element, 13: anal fin origin, 14: pelvic fin origin, 15: tip of lower jaw, 16: tip of upper jaw, 17: posterior edge of maxilla, 18: lower pectoral fin insertion, 19: upper pectoral fin insertion.

FIGURE 8. Male pigmentation of A) Etheostoma rupestre rupestre—47 mm SL, Cottondale Creek, County Road 32, Tuscaloosa, Alabama (photo by K. Boone), B) E. r. piersoni—61 mm SL, Chilatchee Creek, Highway 5, 1 mile north of Alberta, Alabama (photo by K. Boone), and C) E. r. uphapeense—45 mm SL, Opintlocco Creek, County Highway 20, ~3 miles East of Tuskegee, Alabama (Photo by B. Hilburn).

Tables

TABLE 10. Means and ranges (parentheses) of widths of lateral blotches and dorsal saddles as well as distances between blotches of the Etheostoma rupestre subspecies. Distances are expressed as percent of standard length.

	BLOTCHES			SADDLES
Taxon	Mean Dist. Btwn. Blotches (%)	Blotch Width (%)	n	Mean Saddle Width (%)	n
E. r. rupestre	4.8 (3.5–7.5)	5.5 (4.2–6.6)	19	8.0 (5.8–9.1)	19
E. r. piersoni	4.6 (2.8–6.6)	6.2 (4.6–8.2)	16	7.9 (6.6–8.8)	17
E. r. uphapeense	5.0 (4.0–6.1)	4.6 (3.8–5.3)	17	6.9 (5.7–8.0)	17
		Total	52	Total	53