Pygmy Snaketail Evaluation

Committee on the Status of Species at Risk in Ontario (COSSARO)
Assessed June 2010 by COSSARO as Endangered
June 2010

Part 1: Current status and distribution

Current designations:

GRANK – G3
NRANK Canada – N1
COSEWIC – Special Concern (COSEWIC, 2008)
SARA – Not listed
ESA 2007 – Not listed
SRANK – S1 (NHIC NatureServe, 30/05/2011)

Distribution in Ontario

Known from a single record on the Namakan River, east of Rainy Lake in northwestern Ontario.

Distribution and status outside Ontario

The Pygmy Snaketail is largely confined to eastern North America. It is known in a line along the Appalachian Mountains from northern New Brunswick to southeast Tennessee. There is an apparently disjunct centre of distribution of the species in Michigan, Minnesota, and Wisconsin and northwestern Ontario. There are 12 known locales for the species in Canada, including two US locations that are on the border. Canadian locations are in New Brunswick (11) and Ontario (1).

Part 2: Eligibility for Ontario status assessment

2.1 Application of eligibility criteria

Taxonomic distinctness

Yes. The species is distinct, with no close relatives, and there are no proposed subspecies.

Designatable Units

Single Designatable Unit. Known from only a single Ontario site.

Native status

Yes
Although recently discovered in Ontario it is undoubtedly native since there is no other plausible explanation for its presence.

Presence/absence

Present
A single exuvia was discovered in Ontario in 2007. Subsequent surveys for exuviae on the Namakan River in 2008, 2009, and 2010 did not find any Pygmy Snaketails but these surveys are inconclusive given the apparent rarity of the species, the remote location, and relatively small amount of survey effort.

2.2 Eligibility results

1. The putative taxon or DU is valid. Yes
2. The taxon or DU is native to Ontario. Yes
3. The taxon or DU is present in Ontario Yes

Part 3: Ontario status based on COSSARO evaluation criteria

3.1 Application of primary criteria (rarity and declines)

1. Global rank
   Threatened
   G3
2. Global decline
   Not in any category
   Short term trend is stable (NatureServe 2011). New Brunswick population apparently stable (COSEWIC 2008).
3. Northeastern North America ranks
   Endangered
   S1, S2, SH, or SX in 10 of 10 (100%) northeastern states/provinces where ranked. Not ranked in Minnesota.
4. Northeastern North America decline
   Not in any category
   The northeastern North American range is largely the same as its global range.
5. Ontario occurrences
   Endangered. Single Ontario occurrence.
6. Ontario decline
   Insufficient information. Recently discovered in Ontario (2007) and no trend data are available.
7. Ontario’s Conservation Responsibility
   Not in any category Ontario’s extent of the global range < 1 %.

3.2 Application of secondary criteria (threats and vulnerability)

8. Population sustainability
   Insufficient information
   Reproductive and recruitment trends are unknown. No Population Viability Analyses have been conducted for the species in Ontario.
9. Lack of regulatory protection for exploited wild populations
   Not in any category
   Not exploited. No evidence of overuse.
10. Direct threats
    Endangered
    Altered flow regimes caused by proposed dams on the Namakan River are a potential threat. This species apparently cannot breed in conditions found below dams (COSEWIC 2008).
11. Specialized life history or habitat-use characteristics
    Threatened
    Associated with cold, clean waters in large rivers and susceptible to local extirpation due to changes in water quality. Apparently cannot breed in conditions found below dams (COSEWIC 2008).

3.3 COSSARO evaluation results

1. Criteria satisfied in each status category

Primary and secondary criteria met in each status category.

Endangered – [2/1]
Threatened – [1/1]
Special Concern – [0/0]

Ontario-specific criteria met in each status category.

Endangered – [1]
Threatened – [0]
Special Concern – [0]

2. Data deficiency

No.

Although recently discovered in Ontario, the presence of an exuvia indicates that the species reproduces successfully in the Namakan River and is not a vagrant.

3. Status based on COSSARO evaluation criteria

The application of COSSARO evaluation criteria suggests that Pygmy Snaketail is Endangered in Ontario.

Part 4: Ontario status based on COSEWIC evaluation criteria

For each criterion below, identify the appropriate status category (Endangered or Threatened) using the COSEWIC criteria. If the species, infraspecific taxon or DU does not meet any of the thresholds for status, then use "Not in any category". If there is not enough information to assess whether the species, infraspecific taxon or DU meets a threshold for status, use "Insufficient information". Sources of information must be cited.

4.1 Application of COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – Decline in total number of mature individuals

Insufficient Information. Recently discovered in Ontario (2007) and no trend data available

Criterion B – Small distribution range and decline or fluctuation

Insufficient Information. Extent of Occurrence and Area of Occupancy <500 km² and known to exist at < 5 locations, but population trends and fluctuations are unknown.

Criterion C – Small and declining number of mature individuals

Insufficient information. Number of mature individuals probably very small (single exuvia discovered in 2007. Subsequent surveys found none, but no population trend data available.

Criterion D – Very small or restricted total population

Endangered D1. Number of mature individuals probably very small (single exuvia discovered in 2007).

Criterion E – Quantitative analysis

Insufficient information No Population Viability Analyses have been conducted for the species in Ontario.

Rescue effect

No. Approximately 90 km to nearest population in Minnesota. This is further than adults are believed to disperse (COSEWIC 2008).

Special concern status

No

4.2 COSEWIC evaluation results

1. Criteria satisfied in each status category

Indicate whether or not a criterion is satisfied in each of the status categories.

Endangered – [yes]
Threatened – [no]
Special Concern – [no]

2. Data deficiency

No
Although recently discovered in Ontario, the presence of an exuvia indicates that the species reproduces successfully in the Namakan River and is not a vagrant.

3. Status based on COSEWIC evaluation criteria

The application of COSEWIC evaluation criteria suggests that Pygmy Snaketail is Endangered in Ontario.

Part 5: Ontario status determination

5.1 Application of COSSARO and COSEWIC criteria

COSSARO and COSEWIC criteria give the same result. Yes.

5.2 Summary of status evaluation

Pygmy Snaketail is classified as Endangered in Ontario.

This dragonfly is black with vivid yellow markings on the abdomen and bright green on the thorax. It is distinguished from other snaketails by its small size and orange-brown markings on the base of the wings. The larvae inhabit gravel beds in large, cold, clean rivers. Adults are rarely seen because they spend much of their time in the forest canopy. The species range is apparently disjunct, with midwestern populations in Wisconsin, Minnesota, and northwestern Ontario and more extensive eastern populations ranging along the Appalachian Mountains from Tennessee to New Brunswick. Pygmy Snaketail is known in Ontario from only a single exuvia (larval skin) collected in northwestern Ontario in 2007. No further Ontario specimens have been found despite searches in subsequent years. It seems to be rare and restricted to high- quality habitat throughout its range. Larvae are susceptible to water pollution, sedimentation, and habitat alteration caused by dams.

Information sources

1. Literature cited

COSEWIC. 2008. COSEWIC assessment and status report on the Pygmy Snaketail Ophiogomphus howei in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 34 pp. (www.sararegistry.gc.ca).

NatureServe. 2011. NatureServe Explorer An online encyclopedia of life. http://www.natureserve.org/explorer/. Accessed Feb. 8 2011

2. Community and Aboriginal Traditional Knowledge Sources

3. Acknowledgements

Appendix 1

Northeastern North America rank, status and decline

Province/state	Subnational rank	Sources	Decline	Sources
CT	Not present			NatureServe 2011
DE	Not present
IL	Not Present
IN	Not Present
IA	Not Present
LB	Not present
KY	S1S2
MA	SX
MB	Not present
MD	Not present
ME	S2S3
MI	S1
MN	SNR
NB	S1
NF	Not present
NH	Not present
NJ	Not present
NS	Not present
NY	S1
OH	Not present
ON	S1
PA	S1
PE	Not present
QC	Not present
RI	Not present
VA	S1S2
VT	Not present
WI	S3
WV	Not present

Occurs as a native species in 11 of 29 northeastern jurisdictions
SRANK or equivalent information available for 10 of 11 jurisdictions = (91%) S1, S2, SH, or SX in 10 of 10 = (100%)