# Hidden diversity in neglected structures: A morphological study of the terminalia of Limnocoris Stål, 1860 (Hemiptera: Heteroptera: Naucoridae), with descriptions of two new species from Brazil and taxonomic notes

## TL;DR

This study explores the hidden diversity in the terminalia structures of Limnocoris water striders from Brazil, describing two new species and revising taxonomic classifications.

## Contribution

The study provides the first detailed descriptions of female terminalia and male genital capsules for 28 Limnocoris species, including two new species.

## Key findings

- Two new Limnocoris species, L. curvipenis and L. sitesi, were described based on unique female terminalia features.
- A distinct male phallosoma was recorded for the first time in the genus Limnocoris.
- Taxonomic revisions resulted in new synonymies and the resurrection of previously synonymized species.

## Abstract

Limnocoris Stål, 1860 (Hemiptera: Heteroptera: Naucoridae) occurs from the United States to Argentina and is the most speciose genus of Naucoridae, with 75 valid species. Four taxonomic revisions were recently published, which facilitates the identification of described species and the discovery of new ones. Nonetheless, the female terminalia of the genus remains mostly unknown and the male genital capsule has been often ignored due to its uniformity among species. This study aims to fill this gap by providing descriptions and photographs of the female terminalia and male genital capsule for 28 species from Brazil, including two that are described here: L. curvipenis
n. sp. and L. sitesi
n. sp. Both of them display diagnostic characters in the female terminalia, and a distinct male phallosoma is herein recorded for the first time in the genus. The following new synonymies are proposed: Limnocoris intermedius Nieser & Lopez-Ruf n. syn. and L. lanemeloi Nieser & Lopez-Ruf n. syn. as junior synonyms of L. decarloi Nieser & Lopez-Ruf, and L. nigropunctatus Montandon n. syn. as junior synonym of L. pauper Montandon. The following species are resurrected from synonymy and their species status are restored: Limnocoris admontandoni La Rivers stat. restit. from synonymy with L. insignis Stål, and L. sattleri De Carlo stat. restit. from synonymy with L. nigropunctatus. Our work reveals a notable diversity in the female terminalia of the taxa examined and provides a basis for future taxonomic and systematic studies on this and other genera of Naucoridae.