Female genitalia of Pero obtusaria Prout, 1928 (Lepidoptera: Geometridae)

Abstract

The female genitalia of Pero obtusaria Prout, 1928 (Lepidoptera: Geometridae) are described and illustrated for the first time and compared to congenerics. The antrum with the dorsal part sculptured with two sinuous longitudinal stripes enables the identification of this species.

Keywords
Azelinini; Ennominae; Pero Herrich-Schäffer, 1855; Pero janichoni Lévêque, 2007; Pero jonesaria (Schaus, 1897)

The original description of the Neotropical geometrid moth Pero obtusaria Prout, 1928 (Lepidoptera: Geometridae: Ennominae: Azelinini) was based on a single male from Matucana, Lima, Peru. Poole (1987) reported additional specimens from close to the type locality, re-described and illustrated the male and its genitalia and described the female for the first time. The presence of P. obtusaria was subsequently reported from the eastern Andes of southern Ecuador (Brehm and Fiedler, 2005) and the coastal valleys of the Atacama Desert of northern Chile (Vargas and Hausmann, 2008), which represent the northern and southern limits of its range, respectively. Later fieldwork in the Atacama Desert revealed that the larvae of P. obtusaria feed on leaves of the shrub Pluchea chingoyo (Asteraceae), appearing to be highly host-specialized (Vargas, 2011). Its egg and first instar were described and illustrated recently (Vargas et al., 2017).

Poole (1987) indicated that the wing maculation of P. obtusaria appeared to be more uniform among the species belonging to Group 15, one of the 19 species groups recognized by him to arrange the more than 300 species included in the New World genus Pero Herrich-Schäffer, 1855. However, he also highlighted that only a few specimens of P. obtusaria from a narrow geographic range were known at that time. In accordance with his alert, variation in the wing pattern of this moth was subsequently found, at least in the southern limit of its range (Fig. 1).

Fig. 1
Wing pattern of specimens of Pero obtusaria collected in the coastal valleys of the Atacama Desert. (A) Male in dorsal view. (B) Female in dorsal view. (C) Female in dorsal view. Scale bars 5 mm.

The 19 species groups of Pero were defined based on morphological features of the male genitalia (Poole, 1987). However, the study of the female genitalia is needed to search for diagnostic characters and to understand better the relationships of the species belonging to this highly diverse genus (Lévêque, 2006, 2007; Dias, 2008). Accordingly, the previously unknown female genitalia of P. obtusaria are described and illustrated for the first time.

Specimens used in this study were collected as adults at light or reared in the laboratory from larvae collected on P. chingoyo in the coastal valleys of the Arica Province, northern Chile, between October 2003 and November 2009. The abdomen of two females was removed and placed in hot 10% KOH for a few minutes. The genitalia were removed, placed in a Petri dish with 70% ethanol for drawing and subsequently slide mounted in Canada balsam. Drawings were made using a stereomicroscope with a camera lucida. Images were captured with a Sony CyberShot DSC-HX200V digital camera. Vouchers are deposited in the “Colección Entomológica de la Universidad de Tarapacá” (IDEA), Arica, Chile.

Female genitalia (Fig. 2). Papillae anales lobe-like, with many hair-like setae. Posterior apophyses elongated, about 1.75 times the length of the papillae anales. Segment VIII cone-like; tergum and sternum fused laterally; anterior apophyses slightly differentiated as small projections on the antero-lateral margin. Lamella postvaginalis with anterior margin broadly concave with small cleft at middle, posterior margin convex at middle, two short transverse stripes close to posterior margin. Lamella antevaginalis a narrow transverse stripe. Ostium bursae wide. Antrum funnel-shaped, dorsal part widely expanded, rectangle-like in ventral view, two sinuous longitudinal stripes. Ductus bursae mostly membranous, distal 2/3 slightly sclerotized and striated. Ductus seminalis arising on the left side of the base of ductus bursae. Corpus bursae membranous, spherical. Signum absent.

Fig. 2
Female genitalia of Pero obtusaria. (A) Ventral view; arrows indicate longitudinal stripes of the antrum. (B) Lateral view. Scale bar 0.2 mm.

Remarks. The female genitalia are variable among the species of Pero. For instance, a signum can be absent or present, displaying a wide range of morphological patterns (Poole, 1987; Pitkin, 2002; Dias, 2008). Poole (1987) illustrated the sterigma and part the basal of the ductus bursae of 15 of the 33 species included at that time in Group 15. The morphology of these structures in P. obtusaria generally fits the pattern of this species group, with a well-developed antrum (Poole, 1987; Lévêque, 2007). Interestingly, two transverse stripes close to the posterior margin of the lamella postvagianlis, similar to those found in P. obtusaria, are found in Pero jonesaria (Schaus, 1897) described from southern Brazil (Poole, 1987). However, the antrum with the dorsal part characteristically sculptured with two sinuous longitudinal stripes enables the identification of P. obtusaria. The female genitalia of another Peruvian representative of Group 15, Pero janichoniLévêque, 2007, were described and illustrated in detail (Lévêque, 2007), enabling further comparisons. The convex posterior margin of the lamella postvaginalis, the extreme reduction of the anterior apophyses and the slightly sclerotized ductus bursae in P. obtusaria contrast with the prominent posterior projection of the lamella postvaginalis, the spine-shaped aspect of the anterior apophyses and the well-sclerotized basal half of the corpus bursae in P. janichoni. All these findings reinforce the suggestion regarding the importance that the study of the female genitalia in Pero can have. Thus, their morphology should be studied in additional species of this highly diverse New World genus.

Acknowledgements

I thank Sebastián Espinoza-Donoso for editing the figures and Lafayette Eaton for checking the English. This study was supported by project UTA-MAYOR 9718-17.

References

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• Vargas, H.A., Oyarzún, F.X., Parra, L.E., 2017. Egg and first instar of the Neotropical geometrid moth Pero obtusaria Prout (Geometridae: Ennominae: Azelinini). J. Lepid. Soc. 71, 50-56.

Publication Dates

• Publication in this collection
  13 June 2019
• Date of issue
  Apr-Jun 2019

History

• Received
  17 Oct 2018
• Accepted
  19 Jan 2019