Journal archives for December 2019

December 09, 2019

Identification of the three most similar species of Diphlebia (Rockmaster damselflies, Eastern Australia)

In posting my own sightings on this site, I found that I was struggling to differentiate the females of the sometimes sympatric species D. coerulescens and D. nymphoides from photographs taken from whatever angle the subjects permitted. More recently, differentiation of male and female D. euphoeoides from D. coerulescens has been an issue of interest on this site; I have often relied on their disjoint known ranges to resolve these questions, but it is appropriate to approach any suggestions of sightings outside those ranges in the spirit of objective scientific enquiry. The information in the Theischinger and Hawking field guide (2006) and the Theischinger and Endersby identification guide (2009) appears quite adequate for identification with a captive or preserved specimen in hand, but often left me in considerable doubt when working from a single opportunistic snapshot. Rather than assuming that females would be conspecific with the nearest Diphlebia males (if any), I decided that I would obtain a copy of W. E. Stewart's definitive 1980 paper on the genus, cited as the basis for the treatment of Diphlebia since the Watson, Theischinger and Abbey guide (1991). The figures that I found most useful for photographic IDs depicted the dorsal and lateral abdominal views, but Stewart's paper was formatted to present this information as compactly as possible, and I found it necessary to construct a composite image that permitted direct comparison on the same page of the patterns for each species. I am now endeavouring to share that image with others here.

Posted on December 09, 2019 09:31 AM by jeff_melvaine jeff_melvaine | 2 comments | Leave a comment