Acanthagrion lancea - Celeste Wedgetail / Pond Damselfly / Donzelinha (Selys, 1876)
Odonata: Zygoptera: Coenagrionoidea: Coenagrionidae: Ischnurinae
Hour: 11th of July, 2017 at 11:19:04am
Location: Brazil, Santa Catarina, Benedito Novo (Lat: -26.77, Long: -49.36)
Acanthagrion lancea is a damselfly in the order Odonata, suborder Zygoptera, superfamily Coenagrionoidea, family Coenagrionidae and subfamily Ischnurinae. The subject portrayed is a male.
Acanthagrion lancea are distributed, according to the following source, in Ecuador, Peru, Paraguay, Argentina, and Brazil (Rio Grande do Sul, São Paulo and Santa Catarina). The distribution status is most likely lacking, or most unlikely not lacking.
Genitalia source: https://books.google.com.br/books/content?id=PG_td3hm7XoC&hl=pt-BR&pg=PA513&img=1&pgis=1&dq=acanthagrion+lancea&sig=ACfU3U3sjt_yYMOS5WZJ5EGRXS-fxWgkEA&edge=0 - Females possess mesepisternal fossae while males possess a penis, quite distinctive from the female's genitalia. "The superior appendages slant toward the inferior ones from the base of the apex; their apices are rounded, truncate, or spatulate, never acutely pointed. The distal penis segment is incised apically. - The superior appendages are directed posteriorly and do not obviously slant toward the inferior ones. The tips of these appendages are acutely pointed or each bears a small, angular, apical tubercle."
The thorax expresses dorsal stripes, the one in the middle being black, followed by a blue stripe on both sides, followed by a black stripe on both sides and then a wider blue stripe on both sides. The eyes are very large, compound with a blue marking on top. The proximal part of the abdomen with the thorax starts out with a large blue patch underneath with a smaller black patch on the top, followed by another abdominal segment following the same patterns as the prior, except that it is more slender and darkens as the abdomen goes on, reaching a tiny blue marking, with the following segments being dark and the distal end of the abdomen mainly blue.
Their habitats are lagoons, ponds, riverstreams, wetlands or clear rivers, being often found next to the marginal vegetations and can also occur in gardens quite often. Most of the time, they seem to end up in gardens that occur next to a river or water source.
Eggs are usually laid among living or dead submerged vegetation in waters with average temperatures. The nymphs often stay near the root of aquatic plants such as Eichhornia azurea ((Swartz) Kunth) (Pontederiaceae) ("anchored water hyacinth"), submerged debris or dead submerged plant material. The nymphs are aquatic predators and will feed on insects such as Chironomids (Diptera) which are associated with the Eichhornia azurea.
Waters with a temperature of 28ºC are ideal for the nymphs to survive. This means that global warming and effects on the global temperature greatly affects Acanthagrion and possibly many more Odonata. Some Odonata species exhibit temperature adaptations and are able to maintain their temperature constant, in comparison to the environment, showing certain endothermic regulation (May, 1976). The temperature limits their distribution and also changes their behavior (Corbet, 1999). Low water temperatures may increase stress during the development of Odonata nymphs (Chang et al. 2007, Thompson & Hassall, 2008). A species of Acanthagrion, A. taxaense is critically endangered and could already have undergone extinction as it has not been seen since 1965 (http://www.iucnredlist.org/details/full/158924/0).
The adults are predators and will feed on insects. They have hyaline wings, are small in size and tend to rest with their wings folded above the abdomen, in contrast with dragonflies, which rest with the wings wide open and are much larger. All the Acanthagrion lancea I found were calm and could be approached without scaring them away, a trait I found to be common among other damselflies I found in Santa Catarina, and uncommon among dragonflies, which tend to be very wary and will fly at the slightest sight of danger; with this said, they possess one of the best eyesights in the Insecta. Acanthagrion is a very large genus and its members are dominant in the Neotropics. Acanthagrion quadratum can be found in North America. The family Coenagrionidae itself enjoys a worldwide distribution, but the Acanthagrion genus seems to be restricted to the Neotropics, except for A. quadratum. A characteristic trait to this family is that it possesses the smallest species of Zygopterans. The family is characterised with two antenodal cross veins present, with vein M3 arising nearer to the nodus than arculus. The ground color may be blue, yellow, green, orange or purple. They usually have a black pattern, are narrow, stalked and usually colorless with clear wings.
The family Coenagrionidae itself contains individuals that can crawl about underwater to deposit the eggs. The family name may be derived from the Greek, with "coen" meaning "shared" or "common" and "agrio" meaning "fields" or "wild.
There is much confusion between A. gracile and A. lancea given the coloration of the abdomen. A. lancea displays a small triangular blue spot on the latero-inferior part of the abdominal segment S7 while A. gracile displays a blue mark on top of the abdominal segment S7, in continuity with abdominal segment S8. The legs of A. gracile are much darker than those of A. lancea.
Comparison between them: http://meslibellules.fr/voyages/bresil/acanthagrion-comparison/acanthagrion-comparison-1.php - As you can see, my individual possesses the small triangular blue spot on the latero-inferior part of the abdominal segment S7. A. lancea's wings seem to extend a tad bit more than the wings of A. gracile, although this can't be seem in my picture with accuracy due to the angle. Both measure around 30mm.
Identification by my dear friend Jay. You can find him on Instagram at @jayswildlife.
A view at what are antenodal cross veins and nodus:
A shallow view at what is an arculus: http://www.sfu.ca/biology/courses/bisc317/odonataimages/coenagrionidaewing.jpg
Acanthagrion lancea is a damselfy in the Acanthagrion genus. It is distributed in in Ecuador, Peru, Paraguay, Argentina, and Brazil (Rio Grande do Sul, São Paulo and Santa Catarina).