Calvert County (MD) Dragonflies and Damselflies: Part Seven – Dragonfly Family Cordulegasteridae

Family: Cordulegasteridae (Spiketails)

For the entire state of Maryland, there are only five known species of this family in the official state record. Of the five species, only two are in the iNaturalist database for southern Maryland with one each for Calvert and St. Marys Counties. The record for each of those species is the result of a single observation. Charles County has yet to be represented in iNaturalist for this family of dragonflies. Once again, much work remains to be done in order to bring the iNaturalist observations in closer harmony to the definitive database of county sightings.

Listed below are the species within the Cordulegasteridae family that have been observed in at least one of the southern Maryland counties and a comparison of the two databases is made (as of January, 2020). As was done with the previous families, I have included with each species a note extracted from the book “Natural History of DelMarVa Dragonflies and Damselflies” by Hal White (reference 1). Of particular relevance for Calvert County, I have also included information on the two species of this family that were observed at the Cove Point LNG Property and reported in “2011-2012 Survey of the Dragonflies and Damseflies (Odonata) of the Cove Point LNG Property (Calvert County, Maryland” by Richard Orr (reference 2).

Brown Spiketail/ Cordulegaster bilineata
S3 Watch List (see below for definition)
The Brown Spiketail was once thought to be a geographical or morphological variant of the Delta-spotted Spiketail, but analysis of the mitochondrial DNA has confirmed it is a separate species. (1)
Cove Point adult abundance and flight period – uncommon/31-Mar to 14-June. (2)
iNaturalist research grade observations:​ Calvert = 0​ St. Marys = 0​​ Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present ​Charles - present

Tiger Spiketail/Cordulegaster erronea
S3 Watch List (see below for definition)
Female spiketails will hover over shallow water and then perform multiple dips of the abdomen vertically into the water like a pogo stick, each time depositing an egg into the stream bottom. (1)
iNaturalist research grade observations:​ Calvert = 1 (June) St. Marys = 0​ Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present​ Charles – present

Twin-spotted Spiketail/ Cordulegaster maculata
Full grown larvae no longer feed in the weeks prior to emergence and the internal processes of metamorphosis occur during this stage. (1)
Cove Point adult abundance and flight period – rare/23 Apr to 10-May. (2)
iNaturalist research grade observations:​ Calvert = 0​ St. Marys = 1 (Apr)​ Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present Charles - present

Arrowhead Spiketail/ Cordulegaster obliqua
S2 State Rare (see below for definition)
Traditionally, actual insect specimens were required to document species for identification and were then stored along with date and locality information. In some instances photographic records have been accepted for documentation purposes. The only record of this species on the DelMarVa peninsula is from a single photograph. (1)
iNaturalist research grade observations:​ Calvert = 0​ St. Marys = 0​​ Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – X St. Marys – present​ Charles - present

Definitions from the Maryland Department of Natural Resources “List of Rare, Threatened, and Endangered Animals of Maryland”:
S2 - Imperiled / State Rare — At high risk of extinction or extirpation due to restricted range, few populations or occurrences, steep declines, severe threats, or other factors. Typically occurring in 6-20 populations.

S3 - Vulnerable / Watchlist — At moderate risk of extinction or extirpation due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors. Typically occurring in 21-80 populations.

Anotado por rosalie-rick rosalie-rick, febrero 10, lunes 20:26

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