Heteragrion species

Ramírez, Alonso & Gutiérrez-Fonseca, Pablo E., 2013, The larvae of Heteragrion majus Selys and H. atrolineatum Donnelly, with a key to known species from Costa Rica (Odonata: Megapodagrionidae), Zootaxa 3609 (1), pp. 96-100 : 99-100

Key to identify the ultimate larval stadium of Heteragrion species from Costa Rica

Although there is a high probability of finding new species of Heteragrion in Costa Rica ( Garrison et al. 2010), we provide the following key as a starting point to separate larvae of known species. It should be emphasized that this key is based on the final larval stadium and might not help in identifying younger individuals.

1. Antennomeres 3–7 with ring of long setae near distal margin ( Fig. 2a )............................................ 2

1’. Antennomeres 3–7 glabrous, without distinct rings of setae.................................................... 4

2. Hind femur> 4 mm ................................................................................ majus

2’. Hind femur <4...................................................................................... 3

3. Antennomere 2 with ring of long setae on apical 1/3 and small scattered scale-like setae on basal 2/3....... erythrogastrum

3’. Antennomere 2 with small scale-like setae without apical ring of setae.................................... albifrons

4. Posterior margins of S7–10 with row of spines, ligula with V-shaped median incision, hind femur <4............ mitratum

4’. Posterior margins of S9–10 with row of spines, ligula with U-shaped median incision ( Fig. 3b ), hind femur 4.. atrolineatum

Figures

FIGURES 2–5. Details of H. majus and H. atrolineatum. 2) Antennae of H. majus (a) and H. atrolineatum (b); 3) dorsal view of ligula of H. majus (a) and H. atrolineatum (b); 4) dorsal and ventral view of the abdomen and base of caudal gills for H. majus; 5) dorsal view of H. majus caudal gills.