Description of the larva of Gomphus sandrius Tennessen (Odonata: Gomphidae)

The final stadium larva of Gomphus sandrius Tennessen is described based on reared specimens from Tennessee. The larva is distinct from G. exilis Selys and G. lividus Selys (the only species in the subgenus Gomphus sympatric with G. sandrius) by the greater width to length ratio of abdominal segment 9 venter (mean 1.82, range 1.69- 1.96 in G. sandrius vs. mean 1.43, range 1.23-1.57 in G. lividus and mean 1.40, range 1.26-1.52 in G. exilis). It differs further from G. lividus in the narrower prementum (2.40- 2.90 mm vs. 3.00-3.75 mm and shorter antennal segment 3 (1.15-1.35 mm vs. 1.50-1.90 mm). The larva of G. sandrius is most similar to the allopatric G. graslinellus Walsh, but antennal segment 3 is shorter (G. sandrius: mean 1.25 mm, range 1.15-1.35 mm; G. graslinellus: mean 1.45 mm, range 1.35- 1.55 mm).