{{Short description|Species of gastropod}} {{use mdy dates|date=February 2022}} {{Speciesbox | taxon = Helminthoglypta walkeriana | status = CR | status_system = IUCN2.3 | status_ref = <ref name=IUCN>{{cite iucn |author=Roth, B. |date=1996 |title=''Helminthoglypta walkeriana'' |volume=1996 |article-number=e.T9859A13022006 |doi=10.2305/IUCN.UK.1996.RLTS.T9859A13022006.en |access-date=15 November 2021}}</ref> | status2 = G2 | status2_system = TNC | status2_ref = <ref name=NS>{{cite NatureServe |title=''Helminthoglypta walkeriana'' |id=2.117652 |access-date=4 July 2023}}</ref> | image = Banded Dune Snail (2647329862).jpg | authority = (Hemphill, 1911) |synonyms_ref= |synonyms= ''Helix walkeriana'' <small>Hemphill, 1911</small> }}
The '''banded dune snail''' or '''Morro shoulderband''' ''('''Helminthoglypta walkeriana''''') is a species of endangered air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the subfamily Helminthoglyptinae.<ref name="WoRMS">{{WRMS species|1352450|''Helminthoglypta walkeriana '' (Hemphill, 1911))}}</ref>
The name stems from the fact that the snails have distinctive spiral shells that are usually banded in different colors. The shells are typically mostly brown, however they can also be a variety of other colors.
==Taxonomy== At the time the species was divided into two subtaxa (subspecies or varieties): ''H. w. walkeriana'' and ''H. w. morroensis.'' The latter was thought to be extinct but was rediscovered. In 2004, it was elevated to species status as ''Helminthoglypta morroensis'' and it inherited the endangered status it had when it was part of ''Helminthoglypta walkeriana''.
Both snails together were known as the '''banded dune snail'''. Today ''H. walkeriana'' proper is the '''Morro shoulderband''', and ''H. morroensis'' is the '''Chorro shoulderband'''.<ref name="five">USFWS. [http://ecos.fws.gov/docs/five_year_review/doc772.pdf Morro Shoulderband and Chorro Shoulderband Five-year Review.] September 2006.</ref>
== Ecology ==
=== Distribution and habitat === thumb|Banded dune snail seen in natural habitat The species is endemic to the area around the cities of Morro Bay and Los Osos in the central coast in San Luis Obispo County and Santa Barbara County, in California. As coastal organisms, the Morro Shoulderband variant primarily occupies coastal dunes, coastal dune scrubs, and maritime chaparral plant communities that are mostly stabilized dune systems. They are most commonly found on sandy soils dominated by woody shrubs.<ref>{{Cite web |title=NatureServe Explorer 2.0 |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.117652/Helminthoglypta_walkeriana |access-date=2024-10-22 |website=explorer.natureserve.org}}</ref> On the other hand, the Chorro Shoulderband snail can also be found in grassland communities and rocky areas. It has also been found that there is a correlation between the Chorro Shoulderband's occurrence and clay and serpentine soils.<ref>{{cite thesis |id={{ProQuest|2691569213}} |last1=Wahlgren |first1=Michael |date=2003 |title=The Current Status of the Morro Shoulderband Snail (''Helminthoglypta walkeriana'') }}{{pn|date=October 2024}}</ref> Despite the slight variety in habitats, the total area of occurrence has been calculated to be as low as 40 km<sup>2</sup> (15 sq mi). It is possible that only a few thousand individuals are living in the world now, mostly consisting of the Morro Shoulderband variety. However, the reproduction frequency of the snails allows them to maintain a population despite the variable conditions of the sandy habitats. The habitats are threatened not only by wind and water that can shift the sand dunes, but also by land conversion, off-road recreation, and the invasion of non-native plants.<ref>{{Cite journal |last=Roth I Tupen II |first=Barry I Jeff II |date=January 2005 |title=New study confirms restricted status of endangered California land snail |url=https://www.hawaii.edu/cowielab/tentacle/tentacle_13.pdf |journal=Tentacle |volume=13 |issue=958–5079 |page=9}}</ref>
=== Diet === Although no study specific to the banded dune snails diet has been performed, it can be assumed that they have similar diets to those of the ''Helminthoglypta'' in similar locations, which consists of dead and decaying plant material. Similarly to other snails, the banded dune snail uses its sense of smell to find food.<ref name="five" /> Within the narrow distribution in coastal dune and scrub communities in western San Luis Obispo County, they typically expose themselves from underneath the sands during wet weather, meaning they are almost solely active during the wet seasons. They seal themselves inside of their shells for months during a drought, but reemerge when rains return.<ref name=":0" />
=== Behavior === The rainy season is the morro shoulderband snail's most active season. After spending many months in prolonged aestivation, they emerge following the first rain of the season. Their activity is reserved to either find food, which they do through their sense of smell, or to reproduce. High humidity correlates with higher levels of activity. Once the weather becomes drier, their activity decreases and they prepare for aestivation. During aestivation, they find shelter in local plants for as long as 170 days. This season can lead to a 40 percent loss in body weight, but this can be regained during the first 24 hours after aestivation.<ref name=":0">{{Cite web |title=Morro Shoulderband (Helminthoglypta walkeriana) {{!}} U.S. Fish & Wildlife Service |url=https://www.fws.gov/species/morro-shoulderband-helminthoglypta-walkeriana |access-date=2024-10-22 |website=www.fws.gov |language=en}}</ref>
=== Life cycle === The life cycle of these snails is made up of two parts based on the dry and rainy weather of the Mediterranean climate regions of California. To survive drier seasons, they go through a period of prolonged dormancy, or aestivation. An epiphragm, a durable seal of dried mucus, is developed over the opening of its shell to protect itself from drying out. The epiphragm is then shed during the late fall and winter once rain begins. Most individual growth and reproduction occurs during the rainy season, when moisture conditions are ideal for feeding. They can mate several times in a single year.<ref name=":0" />
=== Reproduction === The reproductive cycle of the banded dune snail can be compared to other related ''Helminthoglypta'' species. Similarly to those species, the snails are hermaphroditic, meaning that all have both male and female reproductive organs. They are typically sexually mature at around 3–4 years of age. Prior to mating, which occurs after the first significant downpours of the wet season, they often engage in courtship behaviors to attract partners, which may include the exchange of pheromones. They generally mate when it is darker on the surface, meaning during overcast days or during the night. After mating, the female parts of the snail fertilize the eggs, then they are laid in shallow holes in sandy soil covered by leaves to protect them from predators or other environmental threats. The eggs, normally laid in small clusters, hatch around six months later.<ref name=":0" />
==Conservation== This snail was placed on the United States' Endangered Species List in 1994. The IUCN Red List considers the snail critically endangered, and NatureServe considers it imperiled.<ref name=IUCN/><ref name=NS/>
The USFWS recommends that the Morro shoulderband be downlisted to threatened status and the Chorro shoulderband be delisted.<ref name=five/>
==References== {{Reflist}}
== External links == * [http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=G00D FWS: Banded dune snail — ''Helminthoglypta walkeriana'' species profile]
{{Taxonbar|from=Q3076450}}
Category:Helminthoglypta Category:Endemic fauna of California Category:Fauna of the California chaparral and woodlands<!---Coastal sage scrub dunes---> • Category:Natural history of San Luis Obispo County, California Category:Natural history of Santa Barbara County, California Category:Endemic molluscs of the United States Category:Critically endangered fauna of California Category:Gastropods described in 1911 Category:Taxonomy articles created by Polbot Category:ESA endangered species Category:Taxa named by Henry Hemphill
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