Leptoxis compacta

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Leptoxis compacta
Leptoxis compacta from the Cahaba River, Shelby County, Alabama - journal.pone.0042499.g004.png
A live individual of Leptoxis compacta
Status TNC G1.svg
Critically Imperiled  (NatureServe) [1]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Caenogastropoda
Family: Pleuroceridae
Genus: Leptoxis
Species:
L. compacta
Binomial name
Leptoxis compacta
(Anthony, 1854) [2]
Synonyms

Melania compacta Anthony, 1854

Leptoxis compacta, the oblong rocksnail, is a species of freshwater snail with an operculum, an aquatic gastropod mollusk in the family Pleuroceridae.

Contents

This species is endemic to the Cahaba River in Alabama, United States. It was thought to be extinct due to habitat loss since it had not been collected since 1933, [3] and was formally declared extinct in 2000. [4] The IUCN Red List had previously listed it as critically endangered in 1996 but there was no survey data available at that time. [4] It was rediscovered in a small section of its previously described habitat in the Cahaba River in 2011, with a formal report published in August 2012. [3] [5]

Molecular systematic analyses are underway to clarify the genetic position of Leptoxis compacta. [3]

Distribution

Distribution map of localities of Leptoxis compacta. Map of the Cahaba River and select tributaries - journal.pone.0042499.g001.png
Distribution map of localities of Leptoxis compacta.

Leptoxis compacta is restricted to a single location in the Cahaba River, where it was rediscovered in 2011. [3] It lives in an unnamed shoal upstream of the Cahaba River and Shades Creek confluence in Shelby County, Alabama. [3]

Historically, Leptoxis compacta was most abundant in the central section of the Cahaba River at Lily Shoals in Bibb County, Alabama. [3] The historical range of Leptoxis compacta extended from Centerville, Bibb County, upriver and into lower Buck Creek in the Valley and Ridge physiogeographic province of the southern Appalachian Mountains. [3]

Specific reasons for the species decline of Leptoxis compacta have not been determined, but it is known that the species was declining in abundance and range by 1935, and it is suggested that factors contributing to the decline included its naturally small range and pollutant loadings to streams from mines and the Birmingham, Alabama metropolitan area. [3]

This species was the only pleurocerid endemic to the Cahaba River that was considered extinct, [3] and had not been found in surveys of the river conducted in 1992, 2005, and 2008. [6] [ page needed ]

This snail is highly susceptible to a single catastrophic extinction event. [3] As such, the species deserves immediate conservation attention. [3] Artificial propagation and reintroduction of Leptoxis compacta into its native range may be a viable recovery strategy to prevent extinction from a single perturbation event. [3]

Description

Leptoxis compacta lectotype. Scale bar is 5 mm. Leptoxis compacta lectotype - journal.pone.0042499.g002A.png
Leptoxis compacta lectotype. Scale bar is 5 mm.

This species was originally described by the American naturalist and malacologist John Gould Anthony in 1854. [2]

The shell of Leptoxis compacta is ovate-conic, smooth, thick and yellowish-green. [2] The spire is obtusely elevated. The shell has about five whorls, which is nearly flat. The body whorl is large, subangulated near the base, with three very dark bands, two of which are below the angle. The penultimate whorl has two bands only, and the lowest of these is nearly or quite concealed by the suture, and on the upper whorl the same band is indicated only by a dark, hair-like line. [2] Sutures are well impressed. The aperture is rather large, ovate, within whitish and banded. [2] The columella is strongly indented, base regularly rounded, without any sinus. [2]

The width of the shell is 10 mm. [2] The height of the shell is 15 mm. [2] The height of the aperture is 7.5 mm. [2]

Most specimens collected from the wild in 2011 had purple pigmentation on the columella indentation, but juveniles propagated in captivity did not have this feature. [3] The external tissue pigmentation of Leptoxis compacta is yellow, mottled with black and includes prominent black bands in the middle of the proboscis and on both eyes. [3] This pigmentation banding pattern is identical to sympatric Leptoxis ampla . [3] Pigmentation patterns and the presence of an ocular peduncle are features that distinguish Leptoxis compacta from sympatric Elimia spp. including Elimia clara , which is conchologically most similar to Leptoxis compacta. [3]

Juvenile Leptoxis compacta shells possess one distinct carina on the main body whorl, which is eventually lost as adults. [3]

radula of Leptoxis compacta SEM images of radulae of the oblong rocksnail (Leptoxis compacta) as collected in 1881 and 2011.png
radula of Leptoxis compacta

The radular structure of Leptoxis compacta is described as including a rachidian tooth with a widely convex basal margin and a blunt central cusp flanked by four to five denticles, with the outermost being weakly developed in most cases. The lateral tooth contains one larger rectangular central cusp that is flanked by four to five outer denticles and three to four inner denticles. The inner marginal teeth contain 10 to 12 denticles, and the outer marginal teeth have 12 to 16 denticles. The outer denticles are often weakly developed. [3]

Ecology and life history

Two Leptoxis compacta eggs. Scale bar = 1 mm Leptoxis compacta eggs - journal.pone.0042499.g007.png
Two Leptoxis compacta eggs. Scale bar = 1 mm

Leptoxis compacta inhabits upstream shoals. [7]

Reproductive behavior was observed on approximately 30 L. compacta individuals collected in 2011 and placed in captivity. Females laid eggs either singly or in short, single lines. [3] Each egg was approximately 0.3 mm in diameter. [3] Average length of the line of eggs was 1.57 eggs (n = 51 egg lines) with a maximum observed length of three eggs. [3]

Related Research Articles

<span class="mw-page-title-main">Cahaba River</span> River in Alabama, United States

The Cahaba River is the longest substantially free-flowing river in Alabama and is among the most scenic and biologically diverse rivers in the United States. It is a major tributary of the Alabama River and part of the larger Mobile River basin. With headwaters near Birmingham, the Cahaba flows southwest, then at Heiberger turns southeast and joins the Alabama River at the ghost town and former Alabama capital of Cahaba in Dallas County. Entirely within central Alabama, the Cahaba River is 194 miles (312 km) long and drains an area of 1,870 square miles (4,800 km2). The name Cahaba is derived from the Choctaw words oka meaning "water" and aba meaning "above"

<span class="mw-page-title-main">Cahaba pebblesnail</span> Species of gastropod

The Cahaba pebblesnail, scientific name Clappia cahabensis, is a species of very small freshwater snail, aquatic gastropod mollusks in the family Lithoglyphidae.

<span class="mw-page-title-main">Pleurocera ampla</span> Species of gastropod

Elimia ampla, common name ample elimia, is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusk in the family Pleuroceridae.

The lacy elimia, also known as the lacey elimia, scientific name Elimia crenatella, is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusk in the family Pleuroceridae.

The hearty elimia, Elimia jonesi, is an extinct species of freshwater snails in the family Pleuroceridae. This species was endemic to Alabama, the United States, with records from the Coosa River. It is now considered extinct, having not been reported since the river was impounded, despite surveys. The specific name jonesi honors Walter Jones, state geologist of Alabama.

The puzzle elimia is a species of freshwater snail with an operculum, aquatic gastropod mollusc in the family Pleuroceridae. This species is endemic to the Cahaba River system of Bibb County, Alabama in the United States

<i>Leptoxis ampla</i> Species of gastropod

Leptoxis ampla, common name the round rocksnail, is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusc in the family Pleuroceridae.

<i>Leptoxis</i> Genus of gastropods

Leptoxis is a genus of freshwater snails with a gill and an operculum, aquatic gastropod molluscs in the family Pleuroceridae.

Leptoxis clipeata, the agate rocksnail, was a freshwater snail in the family Pleuroceridae. Like all Leptoxis, the species required free-flowing unpolluted water. It was endemic to parts of the Coosa River in Alabama, now impounded.

Leptoxis foremani, the interrupted rocksnail, is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusk in the family Pleuroceridae.

The black mudalia is a species of freshwater snail in the family Pleuroceridae. It is endemic to the Black Warrior River system of Alabama in the United States. It was thought to be extinct until it was rediscovered during a 1996 survey.

<span class="mw-page-title-main">Plicate rocksnail</span> Species of gastropod

The plicate rocksnail, scientific name Leptoxis plicata, is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusk in the family Pleuroceridae.

<span class="mw-page-title-main">Painted rocksnail</span> Species of gastropod

The painted rocksnail is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusc in the family Pleuroceridae.

Leptoxis torrefacta, or the squat rocksnail, is a species of freshwater snail in the family Pleuroceridae. This species was endemic to Alabama, the United States, with records from the Coosa River. It is now extinct, presumably as a consequence of the impoundment of the Coosa River mainstem.

<span class="mw-page-title-main">Flat pebblesnail</span> Species of gastropod

The flat pebblesnail is a species of freshwater snail, an aquatic gastropod mollusk in the family Lithoglyphidae.

<i>Elimia virginica</i> Species of gastropod

Elimia virginica, common names the Piedmont elimia or Virginia river snail, is a species of freshwater snail with an operculum, an aquatic gastropod mollusc in the family Pleuroceridae.

<i>Elimia showalteri</i> Species of gastropod

Elimia showalteri, common name the compact elimia, is a species of freshwater snail in the family Pleuroceridae.

References

This article incorporates public domain text from the reference [2] and CC-BY-2.5 text from the reference [3]

  1. ↑ NatureServe (31 May 2024). "Leptoxis compacta". NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer. Arlington, Virginia: NatureServe. Retrieved 21 June 2024.
  2. 1 2 3 4 5 6 7 8 9 10 Anthony J. G. (1854). "Descriptions of new fluviatile shells of the genus Melania Lam., from western states of North America". Annals of the Lyceum of Natural History of New York 6: 80-130. page 122. Plate III, figure 22.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Whelan, N. V.; Johnson, P. D.; Harris, P. M. (2012). Gratwicke, B. (ed.). "Rediscovery of Leptoxis compacta (Anthony, 1854) (Gastropoda: Cerithioidea: Pleuroceridae)". PLOS ONE. 7 (8): e42499. Bibcode:2012PLoSO...742499W. doi: 10.1371/journal.pone.0042499 . PMC   3414462 . PMID   22905139. Open Access logo PLoS transparent.svg
  4. 1 2 Bogan, A.E.; et al. (Mollusc Specialist Group) (2000). "Leptoxis compacta". IUCN Red List of Threatened Species . 2000: e.T11774A3304833. doi: 10.2305/IUCN.UK.2000.RLTS.T11774A3304833.en . Retrieved 21 June 2024.
  5. ↑ Lamb, E. (8 August 2012). "Rumors of the Oblong Rocksnail's Demise Were Somewhat Exaggerated". Scientific American . Archived from the original on 29 April 2015.
  6. ↑ Tolley-Jordan, L.R. (2008). The biology of Pleuroceridae (Gastropoda: Caenogastropoda) in the Cahaba River Basin, Alabama (PhD). Tuscaloosa: University of Alabama. OCLC   501193444.
  7. ↑ U.S. Fish and Wildlife Service (April 2022). "Species Status Assessment Report for the Oblong Rocksnail". Version 1.0. Atlanta, Georgia: U.S. Fish and Wildlife Service. Retrieved 21 June 2024.

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