Dicterias atrosanguinea, Selys, 1853

Vilela, Diogo Silva, Guillermo-Ferreira, Rhainer & Cordero-Rivera, Adolfo, 2018, Description of the female of Dicterias atrosanguinea Selys 1853, with notes on male genital ligula and male behavior (Odonata: Dicteriadidae), Zootaxa 4374 (3), pp. 441-450 : 442-449

Description of Dicterias atrosanguinea female

Figs. 2 , 3 , 4a , 5 , 7c .

Specimens examined. 2 females. Brazil, Pará state, Agropalma property, -2.3568°, -48.7190°, 2 xi 2016, altitude 50 m, specimen code ACR-04471 deposited at ECOEVO, Cordero-Rivera, A. leg. ; Brazil, Amazonas state, Manaus , -2.8460°, -60.9165°, 9 vi 2017, altitude 92 m, MAN-01 deposited at LESTES, Guillermo-Ferreira, R. leg.

Head. Labium pale olive green, palps and apical teeth olive green and pale brown; labrum green, anteclypeus and postclypeus brown, clypeus brown ( Fig. 2a ); antefrons with a green longitudinal stripe; postfrons and remainder of the head brown, except for two green spots bordering the lateral ocelli; occipital bar dark brown, postocular lobes brown, with small green spots at apex ( Fig. 2b ). Eyes dark brown dorsally, yellowish brown ventrally ( Fig. 2 ).

Thorax. Prothorax brown medio-dorsally, green laterally at apex of propleuron, middle lobe with two green spots medially, anterior lobe with discrete green spots laterally. Pterothorax with a blue-green mid-dorsal stripe, with inferior portion of pterothorax brown; mesepimeron and metepisternum with a blue-green stripe above and brown below, metepimeron yellow; mesinfraepisternum and mesothoracic coxae mostly blue; metathoracic spiracle yellow; metinfraepisternum and metathoracic coxae yellow with small dark irregular spots ( Fig. 2 ).

Wings. Hyaline, with pruinose spots at each wing base ( Fig. 2a ), venation brown. Pterostigma reddish brown bordered by brown venation. Wing venation: similar to males and identical in both females, RP1,2 merging with RA 3 (HW) or 4 (FW) cells beyond quadrangle, descending to an oblique vein 2 cells distal to arculus ( Fig. 3 ).

Abdomen. Brown with greenish spots as follows: dorso-lateral regions of S1 and S2, more than two thirds of dorso-lateral S3, one third of S4 and S5; S6–10 brown with black thin longitudinal stripes ventrally; S8 with a small white pleural spot; S9 with a "m-shaped” black spot; S10 dark brown. Ovipositor and appendages brown ( Figs. 4a ) and morphologically very similar to H. amazona , except for shorter styli and cerci (See Figs. 5 , 6 for a comparison).

Measurements. Total length: 30.3–32.2; abdomen length: 21.9–23.5; FW length: 22.5–25.3, HW: 20.4–22.9.

Differential diagnosis. The female of D. atrosanguinea can be easily distinguished from the female of H. amazona , its most similar and most closely related species, especially by its color pattern and size (30.3–32.2 and 45.9, respectively). Females of H. amazona have a green-olive thoracic coloration, which contrasts with thin brown stripes ( Fig. 4b ), whereas D. atrosanguinea females have a blue-green coloration contrasting with thicker brown stripes ( Fig. 4a ). The anal appendages of these two species are similar in morphology, although the styli are longer in H. amazona . The anal appendages of H. amazona are olive-green with brown cerci and olive paraprocts, whereas D. atrosanguinea shows a dark brown pattern throughout the entire length of the anal appendages ( Fig. 4a ).

Habitat and ecology. Males of D. atrosanguinea were found perched on marginal vegetation at small "igarapés" (i.e. streams), where they remained immobile for long periods (even hours; Fig. 7a ). In Pará, sometimes two males were found within 50 cm of each other ( Fig. 7b ), apparently ignoring each other, except when one of them flew to interact with another conspecific individual, after which both D. atrosanguinea males engaged in an agonistic interaction, flying in fast circles, while ascending to tree canopies. After a while, one male, presumably the winner of the interaction, returned to the stream. Sometimes males also interacted with males of other damselflies, but very briefly. One of the examined females (Pará) was observed in the forest, perched with the wings out-spread in a sunny spot ( Fig. 7c ), whereas the other female (Amazonas) was caught in tandem with a male. Males were found on the stream only on sunny days. During cloudy days with only occasional periods of sunlight, individuals flew down from the canopy during those intervals and perched on vegetation near the water. During intermittent overcast days, some individuals were seen perched at about 2–3 m on small trees in the forest. They appeared wary, and would fly immediately to the canopy upon our approach. Except for the tandem pair, we observed no copulatory or oviposition behavior during the days of observations of males at the streams.

Remarks on male genital ligula. The male genitalia of D. atrosanguinea ( Fig. 8a ) and H. amazona ( Fig. 8e ) are quite similar ( Fig. 8b and f , respectively), as stated by Dunkle (1991) in his revision of Dicteriadidae and as illustrated by Garrison et al. (2010). However, the lateral lobes are different between the species. In D. atrosanguinea , the lateral lobes are curved, with a sharp acuminate tip ( Fig. 8c, d ), whereas in H. amazona the lateral lobes have a broader tip, similar to a spatula ( Fig. 8g, h ). In both species these lobes have no spines, but spines were abundant on the subterminal part of the ligula of D. atrosanguinea ( Fig. 8d , red arrow), while spines are absent in H. amazona ( Fig. 8h , red arrow). Very large bristles are present on the shaft of both species.

Figures

FIGURE 3. Wings of Dicterias atrosanguinea, female from Pará, Brazil.

FIGURE 4. Females of Dicterias atrosanguinea from Pará, Brazil (a) taken in 2 xi 2016, by ACR and Heliocharis amazona from Chapada dos Guimarães, Brazil (b) taken in 24 x 2015, byACR.

FIGURE 5. Dicterias atrosanguinea, female from Pará, Brazil.Anal appendages in dorsal (a) ventral (b) and lateral (c) view.

FIGURE 6. Heliocharis amazona, female from Rondônia, Brazil. Anal appendages in lateral view. Courtesy of Rosser W. Garrison.

FIGURE 7. Dicterias atrosanguinea males (a, b) and female (c) in the field study, Pará, Brazil, 2 xi 2016, by ACR.

FIGURE 8. Male of Dicterias atrosanguinea from Pará, Brazil (a) taken 2 xi 2016, by ACR, its genital ligula (b), the lateral lobes (c) and a detail of the subterminal part of the ligula with tiny spines (d, red arrow). Male of Heliocharis amazona from Chapadados Guimarães, Brazil (e) taken 21 x 2016, by ACR, its genital ligula (f), the lateral lobes (g) and the subterminalpart of the ligula, lacking spines (h, red arrow). SEM images taken in CACTI (Univ.de Vigo), by ACR.

FIGURE2. Dicterias atrosanguinea, femalefrom Pará,Brazil.Pterothorax dorsal(a)and lateral (b) view.Preserved specimen. Photo taken in 23 xi 2016 in Pontevedra, Spain, by DSV.