Roblinella agnewi

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

View Printer Friendly

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	MOLLUSCA	GASTROPODA	STYLOMMATOPHORA	CHAROPIDAE

Scientific Name:

Roblinella agnewi

Species Authority:

(Petterd, 1879)

Common Name/s:

English

–

Silky Snail

Assessment Information [top]

Red List Category & Criteria:	Vulnerable D2 ver 2.3
Year Published:	2000
Annotations:	Needs updating
Assessor/s:	Bonham, K. (Mollusc Specialist Group)
Reviewer/s:	Seddon, M.B. (Mollusc Red List Authority)
Contributor/s:
Justification: A previous disjunct record has now been shown to be a different taxon, hence this species is now confirmed to have a very restricted distribution.

Geographic Range [top]

Range Description:	The species is known only from a number of sites on the eastern face of Mt Wellington. It may exist elsewhere, especially in the same mountain range, but considerable searching has failed to reveal specimens elsewhere. Five localities are recorded (K. Bonham, unpub. data), relatively close together, so that it is just conceivable that all could be impacted by a single event (e.g., catastrophic fire). With further searching this number will increase but there is still some case for treating the species as present in a single location (K. Bonham, pers. comm). Extent of occurrence (EOO) (based on currently known records) is approximately 4 km². EOO is likely to be higher with more records but is quite likely to be less than 20 km². There has been no evidence of decline in range.
Countries:	Native: Australia (Tasmania)
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Much more would need to be known to determine if species consists of close subpopulations or a single subpopulation. Conceivably the latter is the case. Population size is very low for a small land snail. The species is extremely difficult to find making estimates very difficult. It could conceivably be as small as 10–20 000 (K. Bonham, pers. comm). It is uncertain whether any population decline has occurred. Collections in the late 1800s suggest species may have been slightly easier to find then than now, but early searchers may simply have known of an area where the species was more common. Any population decline which occurred may have been due to a severe bushfire in 1966, which burnt through most of the species’ range.
Population Trend:	Unknown

Population:

Much more would need to be known to determine if species consists of close subpopulations or a single subpopulation. Conceivably the latter is the case. Population size is very low for a small land snail. The species is extremely difficult to find making estimates very difficult. It could conceivably be as small as 10–20 000 (K. Bonham, pers. comm).

It is uncertain whether any population decline has occurred. Collections in the late 1800s suggest species may have been slightly easier to find then than now, but early searchers may simply have known of an area where the species was more common. Any population decline which occurred may have been due to a severe bushfire in 1966, which burnt through most of the species’ range.

Population Trend:

Unknown

Habitat and Ecology [top]

Habitat and Ecology:	Subalpine shrubby forest. It lives mainly in open boulder fields (these are typically 50 m to hundreds of metres wide) which are just lightly vegetated with wet scrub forest trees/shrubs (K. Bonham, pers. comm). Nothing is known of life history parameters (age at maturity, life span, etc).
Systems:	Terrestrial

Threats [top]

Major Threat(s):	Bushfires: The species is protected from fire in most places to a large degree by its specialised habitat. Some specimens occur in areas prone to fire, but fire would not be able to destroy the species altogether by itself (K. Bonham, pers. comm). The species may indeed be extremely fire sensitive, due partly to its naturally low population densities, and that the very large scree blockfields within its limited range explain its ability to survive and its inability to spread further (K. Bonham, pers. comm). In the long term, climate change as species occupies a narrow altitude band (700–1,000 m on a mountain 1,270 m high) and may have difficulty surviving a temperature change of several degrees.

Major Threat(s):

Bushfires: The species is protected from fire in most places to a large degree by its specialised habitat. Some specimens occur in areas prone to fire, but fire would not be able to destroy the species altogether by itself (K. Bonham, pers. comm). The species may indeed be extremely fire sensitive, due partly to its naturally low population densities, and that the very large scree blockfields within its limited range explain its ability to survive and its inability to spread further (K. Bonham, pers. comm).

In the long term, climate change as species occupies a narrow altitude band (700–1,000 m on a mountain 1,270 m high) and may have difficulty surviving a temperature change of several degrees.

Citation:	Bonham, K. (Mollusc Specialist Group) 2000. Roblinella agnewi. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 20 May 2013.
Disclaimer:	To make use of this information, please check the <Terms of Use>.
Feedback:	If you see any errors or have any questions or suggestions on what is shown on this page, please fill in the feedback form so that we can correct or extend the information provided