Common & Slender Baskettail Comparison

In most of New Jersey the Common Baskettail (Epitheca cynosura) is the default species, although it has yet to be reported in the southernmost counties. Slender Baskettail (Epitheca costalis), formerly called Stripe-winged Baskettail, has been reported from several counties and should be looked for throughout the state.

Until recently, little was known about the differences between these species and even now in-hand ID is difficult at best. Field ID is even harder and may be impossible with the current state of knowledge. The exact relationship of these species and others within the Baskettail complex is still under review and the ID characters are poorly understood.

The marks mentioned in the following table are drawn mainly from Abbott's Dragonflies and Damselflies of Texas but also from scans supplied by Nick Donnelly: (Any errors of interpretation are mine, not theirs)

Common Baskettail (E. cynosura)

Slender Baskettail (E. costalis)

Abdomen often spindle shaped, widest at S5 Abdomen narrow behind S3
S3 not constricted, rather parallel sided S3 strongly constricted with concave sides
male cerci short, usually divergent in dorsal view male cerci over 3.4mm, usually nearly parallel
cerci with lateral keel well developed, ventral angle thinner and more angled> cerci with poorly developed lateral keel and more rounded ventral angle
female cerci less than 2.25mm> female cerci longer than S9+S10
hindwing with variable basal spot hindwing basal spot limited or absent

Note that almost all of these marks are tendencies. Field ID is not going to be very reliable, especially when you must consider Spiny and Beaverpond Baskettail. To some degree the marks mentioned above may pertain to Texas specimens. To my eye, our Common Baskettails seem to have rather parallel-sided abdomens, with Beaverpond exhibiting a "spindle" shape.

Following are two sets of scans from Nick Donnelly which show the differences in S3 and the cerci. The second set includes Dot-winged Baskettail, which doesn't occur in New Jersey.