Research Article |
Corresponding author: Nathan V. Whelan ( nathan_whelan@fws.gov ) Academic editor: Thierry Backeljau
© 2017 Nathan V. Whelan, Paul D. Johnson, Jeffrey T. Garner, Ellen E. Strong.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Whelan NV, Johnson PD, Garner JT, Strong EE (2017) On the identity of Leptoxis taeniata – a misapplied name for the threatened Painted Rocksnail (Cerithioidea, Pleuroceridae). ZooKeys 697: 21-36. https://doi.org/10.3897/zookeys.697.14060
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The Painted Rocksnail, currently known as Leptoxis taeniata, is a federally threatened species native to the Mobile River basin in Alabama, USA. Presently restricted to four disjunct populations, the species is at considerable risk of extinction after a range decline of over 95% in the 20th century because of habitat alteration following impoundment of the Coosa River. Here, we reassess the identity and historical range of the Painted Rocksnail to improve communication and conservation efforts for the species. We determined that L. taeniata is a synonym of L. picta and that the name L. taeniata has been misapplied to the current concept of the Painted Rocksnail for which L. coosaensis is the oldest available name. Leptoxis coosaensis and L. picta are herein redescribed. After examination of historical material, we determined that records of the Painted Rocksnail outside the Coosa River drainage were misidentifications. Thus, we redefine the historical range of the Painted Rocksnail as restricted to the Coosa River and select tributaries above the Fall Line at Wetumpka, Alabama, rather than extending into the Alabama River as previously thought. Leptoxis coosaensis is in dire need of conservation, and management plans should take into consideration the revised historical range of the species.
Gastropoda , snails, Pleuroceridae , nomenclature, taxonomy, Mobile River Basin
The Painted Rocksnail is a riverine gastropod in the family Pleuroceridae that is listed as threatened under the US Endangered Species Act (
The scientific name of the Painted Rocksnail is Leptoxis taeniata (Conrad, 1834) (
Type material of L. coosaensis and its synonyms and other specimens showing conchological variation seen in L. coosaensis. AUSNM 121295, Anculosa coosaensis Lea, 1861 (lectotype) B
Pleurocerid species display high levels of morphological variation in their shells, which can overlap between close relatives (
In addition to examining type and historical material (Fig.
Type and topotypic material of L. picta and its synonym L. taeniata. A, BUSNM 12074, Anculosa picta Conrad, 1834 (possible syntypes) C
We also considered the historical range of the Painted Rocksnail as presently understood from a biogeographic perspective. The Alabama River is exclusively below the Fall Line, a major physiographic break that separates the Gulf Coastal Plain from the Appalachian Highlands (
Despite examining records at seven major natural history collections [
Leptoxis picta was described from the same location as L. taeniata. The original description of L. picta is sufficiently vague that it could be applied to multiple Mobile River drainage Leptoxis species. Leptoxis picta was described as, “Shell sub-oval, shoulder obtusely rounded; aperture ovate, large; columella callous above; epidermis olive, with numerous quadranglular small spots disposed in revolving lines, strongly marked in the aperture” (
Taking all the above into consideration, we have concluded that the type material of L. taeniata and L. picta represents the same taxonomical species and that the two are synonyms. Leptoxis picta was described four months prior to L. taeniata and thus has priority under Article 23 of the International Code of Zoological Nomenclature (ICZN). Nevertheless, the current concept of the Painted Rocksnail represents a unique monophyletic clade in phylogenetic analyses of Leptoxis species, and possesses body coloration patterns (Fig.
Anculosa
coosaensis
Lea, 1861: 54; 1863a: 257–258, pl. 35, fig. 65; 1863b: 79–80, pl. 35, fig. 65. Lectotype
Anculosa
aldrichi
Goodrich, 1922: 31, pl. 1, figs. 1, 2. Holotype
Anculosa
brevispira
Goodrich, 1922: 35, pl. 1, fig. 6. Holotype
Anculosa
choccoloccoensis
Goodrich, 1922: 34, pl. 1, fig. 7. Holotype
Anculosa taeniata lucida Goodrich, 1944: 42. Type material not located, potentially lost. “Coosa [River] tributaries.”
Other references:
Anculosa coosaensis
—
Leptoxis
taeniata
—Haldeman 1848: 3, pl. 3 figs. 71–72;
Anculosa
taeniata
—
Anculotus taeniatus —Reeve 1860: pl. 6, fig. 50. [Not L. taeniata of Conrad]
Shell ovate, two to four whorls, spire often reduced to obsolete but sometimes elevated with obtuse apex. Aperture large, ovate, at least half the height of body whorl. Reddish brown spiral bands typically present, usually four in number, almost always interrupted. Columella often purple. Head-foot and mantle pigmented orange, mottled with black, with one transverse black band across middle of snout and one transverse black band across middle of head. Clutches small (<6 eggs), with minimal organic and/or inorganic matter incorporated into external casings.
Coosa River above the Fall Line from Wetumpka, Alabama, upstream to the confluence of Terrapin Creek and the Coosa River in Cherokee County, Alabama. Some large Coosa River tributaries including Choccolocco, Buxahatchee, Talladega, and Terrapin creeks.
Four disjunct populations: Choccolocco Creek, Talladega County, Alabama; Buxahatchee and Watson creeks, Shelby County, Alabama; Ohatchee Creek, Calhoun County, Alabama; Logan Martin Dam tailwaters of the Coosa River, Shelby-Talladega counties, Alabama.
We have been unable to locate type material of Anculosa taeniata lucida Goodrich, 1944. No holotype was designated, nor was a figure provided, but based on the original description and the type locality of tributaries of the Coosa River, we conclude that this entity does not merit recognition at the subspecies level and synonymize it with L. coosaensis.
Anculosa
picta
Conrad, 1834a: 343, pl. 1, fig. 16. Possible syntype
Anculosa
taeniata
Conrad, 1834b: 63. Lectotype
Other references:
Leptoxis picta
—Haldeman 1848: 3, figs. 74–80;
Anculosa
picta
—
Shell globose, larger shells elongately globose, two to three whorls, spire reduced to obsolete. Reddish brown spiral bands typically present on smaller shells, often faded on larger shells, usually four in number, often interrupted. Head-foot and mantle pigmented orange, mottled with black. Egg clutches spiral, 10-11 eggs per clutch on average, with minimal organic and/or inorganic matter incorporated into external casings.
Alabama River from Claiborne, Alabama, upstream to mouth of Coosa River. Coosa River below Wetumpka.
Disjunct populations in the Alabama River from river mile 46.0 in Monroe-Clarke counties, upstream to approximately river mile 231.5, near the Lowndes/Dallas county line. One recently reintroduced population in the Cahaba River at Centreville, Bibb County, Alabama (P.D. Johnson unpublished data.)
Today, the Painted Rocksnail, i.e. Leptoxis coosaensis, is mostly restricted to Coosa River tributaries (Fig.
Leptoxis coosaensis is listed as threatened under the Endangered Species Act as “L. taeniata” (
Listing of this species was based, in part, on the misperception that the historical distribution included a long stretch of the Alabama River from which it had been extirpated during the 20th century (
The historical range of L. coosaensis just in the Coosa River proper is a distance of approximately 317 km (Fig.
We thank John Slapcinsky (