pronghorn clubtail

LC - Least Concern

N5 - Secure

SNR - Unranked

not listed

Pronghorn clubtail is a relatively robust, medium-sized dragonfly. It occurs mostly in central United States and southern Canada. In Minnesota it is most common in the central and north-central regions, less common in the metro and southeast regions, rare in the Arrowhead, and absent from the southwest.

Adults are 1¾″ to 23⁄16″ (44 to 55 mm) long. The body is black with extensive yellow markings.

The head is small. The face is greenish-yellow. The large compound eyes are blue or gray and do not meet at the top of the head. The area behind the compound eyes at the top of the head (occiput) on both sexes is yellow.

The thorax is yellowish-green or greenish-yellow with several black stripes. The middle stripe on the upper side (middorsal stripe) is broad and has parallel sides. On each side there are two upper stripes (humeral and antehumeral stripes) that are partly fused together but separated in the middle by a thin pale stripe.

The abdomen is slender and black with yellow markings. The upper (dorsal) surface of abdominal segments 1 through 7 have yellow, elongated, triangular spots. Segment 8 has a triangular spot at the base and sometimes a thin line extending from the triangle to the rear margin of the segment. Segment 9 has a broad stripe from the base top the rear margin. Segment 10 has a narrower stripe. Segments 7, 8, and 9 are expanded into a noticeable “club”. The sides of segments 8 and 9 have bright yellow along the entire margin. At the tip of segment 10 the male has a pair of distinctive, widely forked claspers (cerci). Each cercus has an outward-pointing “horn”, like a pronghorn antelope, for which this dragonfly gets its common name.

The legs are dark brown to black. The third leg segment (femur) on the female is streaked with green, on the male it is entirely black. The upper (dorsal) surface of the fourth leg segment (tibia) on both sexes is yellow.

The wings are clear except for a dark cell (stigma) on the leading edge near the tip. The vein on the leading edge (costa) of each wing is bright yellow.

Total length: 1¾″ to 23⁄16″ (44 to 55 mm)

Ponds, lakes, and slow streams.

Mid-May to mid-August

Sources

7, 17, 27, 29, 30

IUCN Red List

Common

This species was formerly classified as Gomphus graslinellus. In an attempt to clarify the relationships of species in the genus Gomphus (Needham, 1947) , five subgenera were proposed. This species was placed in the subgenus Phanogomphus. In later years, several other subgenera were defined. Nine of the genera were grouped in what was called the Gomphus complex. A recent phylogenetic analysis (Ware, et al., 2017) raised all nine subgenera in the complex to genus level, and Gomphus graslinellus became Phanogomphus graslinellus.