Crystallaria cincotta, Welsh, Stuart A. & Wood, Robert M., 2008

Welsh, Stuart A. & Wood, Robert M., 2008, Crystallaria cincotta, a new species of darter (Teleostei: Percidae) from the Elk River of the Ohio River drainage, West Virginia, Zootaxa 1680, pp. 62-68 : 64-67

Crystallaria cincotta , new species

Diamond Darter

Fig. 2 , Table 1

Holotype. UMMZ 233255, 73 mm SL, West Virginia, Kanawha Co., Elk River, 1.6 km upstream of mouth of Big Sandy Creek, Clendenin, WV, 18 July 1991, D.A. Cincotta , M.E. Hoeft, and S.F. Morrison.

Paratypes. West Virginia. USMF (Frostburg State University, Frostburg, MD) 200616 (1, 73 mm SL) taken with holotype. USMF 200617 (1, 76), Kanawha Co., Elk River, 1.6 km upstream of mouth of Big Sandy Creek, Clendenin, WV, 25 Aug 1999. USMF 200618 (2, 75–76) Kanawha Co., Elk River, 150 m downstream of mouth of Big Sandy Creek, Clendenin, WV, 29 Aug. 2003. USMF 200619 (2, 76–77) Kanawha Co., Elk River, 150 m downstream of mouth of Big Sandy Creek, Clendenin, WV, 8 July 2005.

Additional material (nontypes).

Ohio. OSUM 8996 (1, 72 mm SL) Washington Co., Muskingum River, 31 Aug. 1888. OSUM 9688 (1, 51) Lawrence Co., Ohio River, 31 May 1899. Kentucky. USNM 63786 (1, 77) Green Co., Green River, 1890. USNM 89467 (2, 37–49) Edmonson Co., Green River, 31 Aug. 1929. FMNH 6825 (1, 67) Lyon Co., Cumberland River, date unknown.

Diagnosis. A species of Crystallaria that differs from populations of C. asprella of the Gulf Coast, lower Mississippi River, middle Mississippi River, upper Mississippi River, and Wabash River by a combination of the following characters: a larger gape width approximately equal to or exceeding the inter-pelvic fin base width, a preorbital blotch distinctly separate from the anterior orbital rim, pelvic fins distinctly falcate in both sexes, cheek scale rows reduced (modally 2), opercle scale rows reduced (modally 2), a high count of mid-lateral blotches (modally 13), a low count of anal-fin rays (modally 13), a low count of dorsal-fin spines (modally 12), and a high count of scales below the lateral line (modally 11).

Description. Morphometric measurements (as percentage of SL) are given in Table 1. Dorsal-fin spines (11–13, modally 12), dorsal-fin rays (11–15, modally 13), anal-fin rays (11–13, modally 13), principal caudal rays (17), lateral-line scales (83–93, modally 87), cheek scale rows restricted to the post-orbital region (1–4, modally 2), opercle scale rows (1-4, modally 2), mid-lateral blotches (12–14, modally 13), breast and belly without scales, gape width approximately equal to or greater than inter-pelvic fin width. Pelvic fins with falcate posterior margin. Preorbital blotch distinctly separate from the anterior orbital rim.

Paratypes (n=6)

Distances Holotype Mean SD Range

Standard length (mm) 73.3 75.4 1.5 73.0–77.3 Snout–occiput 215.4 211.9 4.8 206–218 Occiput–first dorsal-fin spine 141.3 146.7 7.3 136–158 Base of fist dorsal fin 283.6 287.5 14.7 273–309 Base of second dorsal fin 137.0 156.0 15.0 139–181 Last dorsal-fin ray–dorsal caudal flexure 262.9 265.4 16.2 239–281 Depth at caudal flexure 84.6 82.5 4.6 76–89

Last anal-fin ray–ventral caudal flexure 241.3 242.8 10.9 228–255 Base of anal fin 182.9 182.8 7.1 172–193 Mid-point between pelvic-fin bases–first anal-fin ray 300.3 305.5 9.5 295–322 Branchiostegal connection–midpoint between pelvic-fin bases 200.7 200.6 6.3 191–207 Snout–branchiostegal connection 136.4 131.6 11.3 114–144 Branchiostegal connection–occiput 171.9 148.1 8.0 138–162 Branchiostegal connection–first dorsal-fin spine 260.0 250.4 8.3 238–261 Occiput–mid-point between pelvic-fin bases 155.4 172.7 11.9 155–192 Mid-point between pelvic-fin bases–first dorsal-fin spine 113.1 127.1 14.2 111–152 Mid-point between pelvic-fin bases–second dorsal-fin insertion 356.9 331.8 17.6 313–361 First dorsal-fin spine–anal-fin insertion 291.8 296.4 10.3 285–310 Anal-fin insertion–second dorsal-fin insertion 105.3 109.7 2.8 106–114 Anal-fin insertion–last dorsal-fin ray 190.7 177.5 13.1 162–195 Second dorsal-fin insertion–last anal-fin ray 177.6 188.0 6.7 180–199 Last dorsal-fin ray–last anal-fin ray 68.9 76.6 6.2 69–84

Last anal-fin ray–dorsal caudal flexure 255.9 252.5 16.2 233–280 Last dorsal-fin ray–ventral caudal flexure 259.6 273.0 7.8 265–286 Snout–anterior margin of eye 87.0 91.0 2.7 88–94

Eye width 77.5 75.3 3.7 71–82

Snout–opercle spine tip 257.2 262.3 5.7 255–271 Anterior internasal width 42.2 49.6 2.0 46–52

Posterior internasal width 55.4 57.9 2.3 56–62

Interorbital width 33.8 30.7 1.4 30–33

Gape width 84.6 81.0 4.6 76–88

Interpelvic base width 73.4 74.4 3.1 70–77 Body is overall translucent. Olive brown melanophores are concentrated as four wide saddles on the back and dorsal sides. Saddles angle anteriad on dorsal sides and are outlined with anterior and posterior dark margins. Between the saddles, olive brown melanophores on scale margins produce a fragmented cross-hatch pattern. The ventral sides of the body and head are silvery white. A preorbital blotch is dark and distinctly separated from the anterior margin of the orbital rim. The mid-lateral pigmentation includes 12–14 oblong olive-brown blotches overlain by an iridescent olive green stripe. Fins are clear with the exception of sparse pigmentation on the caudal fin.

Comparisons. Crystallaria cincotta differs from populations of C. asprella of the Gulf Coast, lower Mississippi River, middle Mississippi River, upper Mississippi River, and Wabash River by a combination of the following characters: gape width approximately equal to or exceeding the inter-pelvic fin base width (gape width 7.3–8.6% SL vs. 3.7–6.1), preorbital blotch distinctly separate from anterior orbital rim vs. preorbital blotch adjoined to or narrowly separate from anterior orbital rim, and pelvic fins distinctly falcate vs. pelvic fins not falcate. Additionally, a combination of the following meristic characters separate C. cincotta from C. asprella ; cheek scale rows reduced (1–4, modally 2 vs. 4–14, modally 11), opercle scale rows reduced (1–4, modally 2 vs. 2–13, modally 4), a higher modal count of mid-lateral blotches (12–14, modally 13 vs. 8–14, modally 10), a lower count of anal-fin rays (11–13, modally 13 vs. 12–16, modally 14), a lower count of dorsal-fin spines (11–13, modally 12 vs. 10–17, modally 14), a higher count of scales below the lateral line (10– 14, modally 11 vs. 7–14, modally 9, Table 2 ). Additionally, C. cincotta differs from the Gulf, lower Mississippi, and upper Mississippi populations of C. asprella by cytochrome b sequence divergence (11.31, 11.95, and 11.84%; Wood and Raley 2000), and net nucleotide divergences of the mitochondrial control region (4.97, 5.25, and 4.39%) and the nuclear S7 intron (2.25, 2.03, and 2.04%; Morrison et al. 2006). Genetic evidence supports the species recognition of C. cincotta . Genetic divergence values of Crystallaria in the Elk River are consistent with divergence values of interspecific or intergeneric divergence ( Wood and Raley 2000).

Crystallaria asprella (N=96) mode (range) Crystallaria cincotta (N=13) mode (range) In a plot of sheared PC2 by sheared PC3, gape width (-0.71) loaded highest on the sheared PC2 axis ( Fig. 3 ). Measurements associated with the posterior region loaded highest for sheared PC3; last ray of second dorsal fin to dorsal caudal flexure (0.30), last ray of second dorsal fin to ventral caudal flexure (0.28), base of anal fin (-0.30), base of second dorsal fin (-0.32), last ray of anal fin to dorsal caudal flexure (0.20), last ray of anal fin to second dorsal fin insertion (-0.22), anal-fin insertion to last ray of second dorsal fin (-0.34). Individuals with high sheared PC3 scores had longer caudal peduncle regions owing to fewer rays in the second dorsal and anal fins, but most populations overlapped along this axis ( Fig. 3 ).

Conservation status. Crystallaria cincotta is extirpated from most of its former range within the Ohio River drainage, and is known only to be extant in the Elk River, West Virginia. Wood and Raley (2000) suggested that the population of Crystallaria in Elk River, West Virginia, should be given federal protection under the U.S. Endangered Species Act based on the scarcity of individuals, the genetic uniqueness and sister group relationship with C. asprella , and cumulative landuse threats within the Elk River drainage. The scarcity of C. cincotta in the Elk River is supported by a total of 12 specimens from extensive sampling efforts from 1980 to 2005. Most collections of C. cincotta have occurred in moderate flows over a sand, gravel, and cobble mix of benthic substrate within lower sections of riffles or upper sections of pools ( Osier 2005). This type of river habitat is vulnerable to substrate embeddedness from siltation, and we have observed large yearto-year changes in substrate embeddedness within the lower Elk River. Grandmaison et al. (2003) reported siltation from current landuse practices as a major concern for conservation of Crystallaria in the Elk River drainage.

Etymology. The name cincotta is in recognition of Daniel A. Cincotta , fishery biologist for the West Virginia Division of Natural Resources, and adjunct professor of ichthyology, West Virginia University. He has devoted a 30 year career toward studies of the diversity of West Virginia fishes, including efforts toward conservation of the Elk River drainage and its diverse ichthyofauna. The common name, Diamond Darter, is in reference to the sparkle from reflected light when viewed with lights during nighttime collections, and also fits the analogy of a diamond as a rare crystal.

Remarks. Given that populations of Crystallaria have been extirpated from many localities within their range, it is difficult to draw precise boundaries around the historical distributions of the two component species. Populations of Crystallaria are considered extirpated in the states of Ohio, Indiana, Illinois, Tennessee, Kentucky and Iowa ( Wood and Raley 2000). While these populations would likely unambiguously assign to one species or the other given availability of museum specimens, without specimens it is difficult to assess the full historical range of either species with any confidence. Presumed extirpated populations of particular interest that we can comment on include those from the Wabash River in Indiana, the lower Cumberland River in Kentucky, the Green River in Kentucky, and the Muskingum River in Ohio. In these cases, the availability of museum specimens allow us to unambiguously assign the populations from the Cumberland, Green, and Muskingum to C. cincotta and the Wabash population to C. asprella based on the diagnostic morphological characters discussed above. We infer that C. cincotta was broadly distributed throughout the Ohio River basin exclusive of populations in the Wabash River in Indiana. These latter populations are referred to C. asprella which is hypothesized to have ranged broadly throughout the Mississippi River basin, the Gulf Coast drainages, and the Wabash River drainage. The assignment of most of the extirpated populations is problematic due to the absence of museum specimens for analysis and an incomplete understanding of the complex drainage history of North America.

Figures

FIGURE 2. Crystallaria cincotta, 75 mm SL male, Elk River, West Virginia.

FIGURE 3. Sheared PC 2 by sheared PC 3 scatter plot of Crystallaria asprella from the Gulf Slope (open squares), lower Mississippi River (open triangles), middle Mississippi River (open diamonds), upper Mississippi River (open circles), and Wabash River (plus signs), and Crystallaria cincotta from the Cumberland River (solid triangle), Elk River (solid diamonds), Green River (solid circle), and Muskingum River (solid square).

Tables

TABLE 2. Meristic data for Crystallaria asprella and Crystallaria cincotta.

Anal-fin rays	14 (12–16)	13 (11–13)
Dorsal-fin rays	13 (11–15)	13 (11–15)
Dorsal-fin spines	14 (10–17)	12 (11–13)
Pectoral-fin rays	16 (15–19)	16 (15–17)
Lateral-line scales	89 (77–96)	87 (83–93)
Scales above lateral line	8 (6–10)	8 (7–9)
Scales below lateral line	9 (7–14)	11 (10–14)
Cheek scale rows	11 (4–14)	2 (1–4)
Opercle scale rows	4 (2–13)	2 (1–4)
Mid-lateral blotches	10 (8–14)	13 (12–14)