Heteragrion icterops Selys, 1862

Vilela, Diogo Silva, Cordero-Rivera, Adolfo & Guillermo-Ferreira, Rhainer, 2019, The female of Heteragrion icterops Selys, 1862 (Odonata: Heteragrionidae) with comments and key on the Brazilian females of Heteragrion group B, Zootaxa 4576 (1), pp. 187-194 : 188-192

Description of Heteragrion icterops Selys, 1862 female

Figs. (3, 6, 7–10, 12)

Material examined. 2♀♀ Brazil, Pará state, Agropalma property (-2.4796, -48.7065), 22.x.2016, altitude 78m, Code CL 063 (described here), deposited at LESTES, Vilela, D.S. leg. , Code ACR-04319, deposited at ECOEVO, Cordero-Rivera, A. leg ; 1♀ Brazil, Pará state, Agropalma property (-2.6050, -48.7381), 15.vi.2017, altitude 78m, Code CL 066 (tandem pair), deposited at LESTES, Guillermo-Ferreira, R. leg ; 2♀♀ Brazil, Pará state ,

Parauapebas (-6.1071, -50.4493), 10.x.2016, Code 3448c, deposited at LABECO, Godoy, B.S. leg., Code 3443c (tandem pair), deposited at LABECO, Godoy, B.S. leg.

Head ( Fig. 7 ). Labium pale; labrum brown with a pale triangular area on middle portion; anteclypeus brown on distal borders, center pale; postclypeus mostly dark brown with 1/3 upper portion yellowish; postfrons black with a yellow longitudinal stripe at level of median ocellus; remaining areas of head brown, darkened at center; small yellow spots laterally to lateral ocelli; back of head pale except for a thin longitudinal black stripe on upper area.

Thorax ( Figs. 8–10 ). Prothorax yellow, except for weak brownish pigmentation on mediodorsal portion and on both sides of middle lobe; posterior lobe black with yellow margins ( Figs. 8–9 ); intersternite as large as setifer with a straight carina, a well-developed dorsal plate (triangular in ventrolateral view), lacking a posterior plate ( Fig. 10 ). Pterothorax with a well-marked thin yellow stripe on medial portion of mesepisternum; remainder of mesepisternum black, except for a pale stripe on its lower portion; mesinfraepisternum pale with a dark stripe on mid portion; mesepimeron black, except for a pale stripe covering its lower 1/3 and almost half of metepisternum; rest of pterothorax pale, except for a small dark stripe at right lower portion of metepimeron ( Fig. 8 ).

Legs ( Fig. 8 ). Light brown, with two small dark spots on femora and the first 0.25 of the tibia, remaining areas of legs pale; spines on the femora about the same size as the space between them, subequal in size except for the last two longer spines, numbering seven on profemora and mesofemora and 12 on metafemora; spines on tibiae 2x longer than the space between them, except for the last three shorter spines, which decreases in size towards the apex, numbering 11 on protibiae and eight on meso and metatibiae.

Wings ( Fig. 12 ). Px 17 in FW and 16 in HW; hyaline with dark brown venation; pterostigma dark brown, proximal side oblique, overlying almost two cells in FW and two cells in HW.

Abdomen ( Figs. 3 , 6 , 8 ). S1–S3 pale laterally, black dorsally, S2–S3 with black apical rings; S4– S6 0.5 black and 0.5 pale laterally, black dorsally with black apical rings; S7 mostly dark brown with pale coloration laterally; S8–S9 dark brown dorsally, pale laterally; S10 mostly pale, with a dark dorsal area. Genital valves pale, tips at same level as posterior margin of S10; dentition even, row of strong teeth not linear, meeting diagonally at the posterior end, the two apical teeth the largest. Basal portion of styli pale, remainder black. Cerci brown, length approximately 0.8 of S10.

Measurements. Total length 35.7, abdomen 28.3, FW 22.5, HW 22.

Variation among examined females: Similar to the described female, except for Px 17 in FW and 15 in HW in two females, pterostigma overlying 1.5 cell in one female. Total length 33.5–35, abdomen 27.4–27.8, FW 22.4– 22.9, HW 21–22.4.

Differential diagnosis. Heteragrion icterops fits in Lencioni’s Group B. Despite being considered similar to the female of H. angustipenne , mainly by their coloration patterns ( Selys 1886), we consider the female of H. icterops closer to H. bariai . Among the females of Group B occurring in Brazil, H. icterops and H. bariai are similar in size (total length 33–36 mm), coloration patterns and genital valve morphology, with the single row of teeth not linear and meeting diagonally at the posterior end ( Figs. 2–3 ). The main differences between these two species lie in intersternite morphology, and the lack of a posterior plate in H. icterops ( Fig. 10 ) that is present in H. bariai ( Fig. 11 ). On the other hand, H. angustipenne have genital valves long, surpassing the posterior margin of S10 and the single row of teeth almost linear in a parallel arrangement ( Figs. 1 , 4 ). Furthermore, H. angustipenne is larger in size (total length> 40mm), a larger species in comparison to H. icterops and H. bariai . Further details on H. angustipenne will be treated in a study that is being prepared by Miguel Stand-Pérez, Leon Pérez-Gutiérrez and Cornelio Bota-Sierra (pers. comm.).

Habitat and ecology. Females of H. icterops were collected in small order streams (igarapés) inside the Amazon forest, hanging on leaves and branches, typical of other congeners. Males also hang from tree leaves over the stream; face-offs in territorial contests between males are a regular sight. Both males and females seem to be shade-seekers. Furthermore, at the sites of collection of H. icterops , we found several specimens of H. silvarum Sjöstedt, 1918 , a widespread species of the Brazilian North, which belongs to Lencioni’s Group A.

Figures

FIGURE 12. H. icterops: BRAZIL: Pará; fore and hindwings.

FIGURES 7–9. H. icterops: BRAZIL: Pará; 7. head, dorsal view; 8. habitus; 9. thorax, dorsal view.

FIGURES 10–11. Intersternites. 10. H. icterops: BRAZIL: Pará; structures of the intersternite, in lateral view. Dorsal plate in lateral and ventrolateral views; 11. H. bariai: BRAZIL: Pará; intersternite structures in lateral view.

FIGURES 1–3. Ventral view of S8–S10, genital valves and cerci; 1. H. angustipenne, Pastaza, Ecuador; 2. H. bariai, Jatún Sacha, Ecuador; 3. H. icterops, Pará, Brazil.

FIGURES 4–6. Lateral view of S8–S10, genital valves and cerci; 4. H. angustipenne, Pastaza, Ecuador; 5. H. bariai, Jatún Sacha, Ecuador; 6. H. icterops, Pará, Brazil.