The year 2008 proved again that there is a steady northward trickle, even a flow, of tropical species from Mexico into the United States. Six species were newly recorded from the Lower Rio Grande Valley of Texas, four of them new for North America north of Mexico, and there was another new record for the United States in southern Arizona. This brief account may assist in their identification when they are found again.
Blue-striped Spreadwing Lestes tenuatus
Males of this woodland-based species have the thorax mostly bright blue, with broad black median and humeral stripes. Only S9 becomes pruinose, a good mark. Some females have a blue-and-black striped thorax just like males, others have the same areas pale blue and metallic brown. A population was found in Santa Ana National Wildlife Refuge, Texas, in September 2008.
Caribbean Darner Triacanthagyna caribbea
This species, about the size of Pale-green and Blue-faced Darners, can be distinguished by its green thorax striped with black. The tip of the male abdomen is pale greenish, unlike larger species such as Regal and Swamp Darners with green-and-black-striped thorax. Neither of those species occurs regularly in the Lower Rio Grande Valley. Caribbean Darners were found at Santa Ana National Wildlife Refuge in November 2007 and September 2008.
Straight-tipped Ringtail Erpetogomphus elaps
This is a small ringtail with a bright green thorax, its only conspicuous marking a half-stripe at T1. The stripe along the top of the abdomen from its base to S7 is light green, the only Arizona ringtail so colored. A male of this species was found at Parker Canyon Schoolhouse, Arizona, in September 2008.
Metallic Pennant Idiataphe cubensis
This small, slender skimmer is dark brown with metallic overtones. About the size of the larger small pennants (Celithemis), it has a tiny brown spot at the base of the hindwings but no hint of the bluish pruinosity of a male Double-ringed Pennant. The sexes look alike, females with a slightly thicker abdomen. It could be mistaken for a setwing except for its perching habits, typically on the tips of vertical twigs and stems. Several individuals were seen at Bentsen-Rio Grande Valley State Park, Texas, in June 2008, after prolonged southerly winds.
Mexican Scarlet-tail Planiplax sanguiniventris
Males have a pruinose blue-black thorax and scarlet-red abdomen, much like male Fiery-tailed Pondhawks, but the base of the abdomen is also red (black in the pondhawk), and the legs are exceptionally long. Females are probably brown but are not described! Male scarlet-tails typically perch and fly actively well out from shore over lakes and ponds. A small population was detected at a flooded resaca in Bentsen-Rio Grande Valley State Park in June 2008, a few persisting at least until early September.
This species is a typical clubskimmer, most likely to be seen in flight or hanging from a shaded branch, but it is slightly smaller than both Pale-faced and Masked Clubskimmers. There are only two rows of cells basal to the anal loop (three in the others), and in males the club is distinctly less prominent than in the larger species. A single individual was found at the NABA Butterfly Garden near Mission, Texas, in February 2008.
Arch-tipped Glider Tauriphila argo
Like other gliders, this species flies incessantly and then hangs up to perch. Between saddlebags and Hyacinth Glider in size, it could be mistaken for any of them, but it differs from the others in being entirely red, females duller than males, with a narrow but prominent hindwing spot. Along with the scarlet-tails, numbers of Arch-tipped Gliders appeared at Bentsen-Rio Grande Valley State Park in June 2008. An individual of the same species was seen at Santa Ana National Wildlife Refuge in September of the same year.