Metrichia, Ross, 1938

Rocha, Isabela Cristina, Santos, Allan Paulo Moreira & Nessimian, Jorge Luiz, 2023, Taxonomic diversity of Ochrotrichiinae (Trichoptera: Hydroptilidae) from Peru with the description of ten new species, a new distributional record, and an updated checklist, Zootaxa 5353 (4), pp. 301-331 : 305-306

Genus Metrichia

Metrichia is a very diverse genus of Hydroptilidae , with 141 described species, most of them occurring in the Neotropics, only four of which are found in the United States ( Thomson 2023). Males are characterized by having an abdomen with pregenital segments variable in shape, usually with one or two pairs of membranous pouches internally, sternum VIII reduced, inferior appendages each with a dorsal hook, and the phallus with one or two large spines subapically. Wing venation varies among species and is easier to observe in well-preserved material.

Flint (1972) and Bueno-Soria & Holzenthal (2003) used the shape and position of internal membranous pouches of the male abdomen and the number and shape of the phallic spines to define six species groups in the genus; they are the Metrichia aberrans , M. campana , M. exclamationis , M. penicillata , M. nigritta , and M. patagonica Species Groups. In our discussion section, we explain why we chose not to allocate the species described here to any of these species groups.

The first record of Metrichia from Peru was M. neotropicalis Schmid 1958 from the Department of Junín, in the central highlands and westernmost Peruvian Amazon. After that, another 13 species were described, almost all of them by Flint & Bueno-Soria (1998) and Oláh & Johanson (2011), mainly from South and Northwest Regions. This paper adds seven new species based on material collected in the departments of Cusco and Madre de Dios , southern Peru, with four of them known from only their respective type locations. The description of M. major sp. nov. adds one more species of Metrichia from high elevations in Peru (more than 2,000 m a.s.l.), along with M. arenifera Flint 1980 , M. gomboska Oláh & Johanson 2011 , M. malada , and M. neotropicalis .