Abstract
Immatures are important sources of information about characters, thus potentially improving classification and phylogenies. Euschistus (Mitripus) grandis Rolston, 1978 occurs in southern and southeastern Brazil. There are no references in the literature about this species other than the original description and distribution records. Our aim is to describe the egg and five nymphal instars of E. (M.) grandis, addressing the ontogeny of the external scent efferent system. Specimens of E. (M.) grandis were collected on Solanum pseudocapsicum Linnaeus (Solanaceae) in São Francisco de Paula, Rio Grande do Sul, Brazil, and reared in the laboratory. The egg of E. (M.) grandis is white and barrel-shaped, chorion translucent bearing spines connected by thin sheets forming polygons. Aero-mycropilar processes translucent and slightly clubbed. The nymphs bear anterior dorsal abdominal scent glands (DAG) with slit-like ostiole continued by a short groove; from the second instar onward median and posterior DAGs with rounded ostiole bearing closing cuticular valve. Spout peritreme flat and curved anteriorly, evaporatorium network-shaped surrounding ostiole plus peritrema; alveoli surface with trabeculae. Nymphs of E. (M.) grandis can be distinguished from other species of Euschistus by the color pattern and morphological features. The most striking morphological characteristic of 4th and 5th instar nymphs of E. (M.) grandis is the broad, deflected projection of humeral angles.
Highlights
Studies on autoecology, behavior and morphology of immatures of insects are relevant for several fields in entomology (BRAILOVSKY et al 1992)
Since most immatures described belong to species of agricultural interest and these are not necessarily closely related species, the information about immature morphology is scattered in the family, making it difficult to recognize patterns within subgroups of Pentatomidae
The eggs of Euschistus fit the external morphology commonly found in Carpocorini (MATESCO et al 2009), namely translucent eggs with spinose chorion
Summary
Behavior and morphology of immatures of insects are relevant for several fields in entomology (BRAILOVSKY et al 1992). The immatures are important sources of information about characters, potentially improving classification and phylogenies (MATESCO et al 2009). Characters of immatures, both eggs and nymphs, can be useful to identifying families, genera and species (SCHWERTNER et al 2002). Most pentatomids are phytophagous and some species are crop pests (GRAZIA et al 1999) This economic aspect stimulated studies on immature stages of the Pentatomidae and the family is the most thoroughly studied for biological aspects among the Heteroptera (BRAILOVSKY et al 1992, YONKE 1991). Our aim is to describe the egg and five nymphal instars of E. (M.) grandis, addressing the ontogeny of the external scent efferent system using light and scanning electron microscopy
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