Macropterous form of Limnocoris siolii (De Carlo, 1966) (Insecta: Heteroptera: Naucoridae) with hemelytra reaching the fifth abdominal tergite

In South America Limnocoris StÃ¥l, 1860 is the most abundant genus among benthic naucorids. Members of Limnocoris are recognized by anteriorly divergent compound eyes and by the presence of a distinct mesosternal carina, which is strongly raised and broad. Limnocoris siolii has been recorded from the Brazilian states of Minas Gerais, Paraná, Rio de Janeiro, and São Paulo. However, but only brachypterous forms with shortened hemelytra not reaching the fourth abdominal tergite (staphylinoid forms) have been known. We report macropterous forms of L. siolii from Parati, Rio de Janeiro State and São José do Barreiro, São Paulo State. The hemelytral surface is granulose, with the claval comissure longer than half of the median length of the scutellum. The claval suture is well defined, the external margin of the embolium is rounded and slightly produced, and its posterolateral angle is continuous with the anterior margin of the hemelytra. Based on the presence of hemelytra leaving a much narrower strip of connexiva exposed, this species is here assigned to the maculiceps group (sensu Nieser and Lopez-Ruf, 2001). No differences in the general appearance of mesosternal carinae of brachypterous forms and the specimens reported here have been found. A key covering a part of the Limnocoris groups, including the new forms of L. siolii, is given.