Abstract.--Two new species from the Chilean coastal desert, Gyriosomus granulipennis and Gyriosomus multigranulosus (Pimeliinae: Nycteliini), are described and included in the most recent key for the genus. Distributional and habitat records, habitus photographs, and illustrations of the pronotum and prosternum for these two new species are included.
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Members of the tribe Nycteliini are found in the neotropics from central Peru to southern Chile and Argentina (Flores, 1997) and also recorded in northeastern Brazil (Flores and Triplehorn, 2002). Gyriosomus Guerin-Meneville is one of the more diverse genera of the Nycteliini, with 35 described species (Flores, 1997). The most recent revision of the genus was made by Kulzer (1959). All species of this genus inhabit northern Chile from Reserva Nacional de Paposo (25°00'S) in Region II to Rancagua (34°11'S) in Region VI (Pizarro-Araya and Jerez, 2004).
Species of Gyriosomus are important components of epigean entomofauna within coastal ecosystems in northern Chile (Pena, 1959; Crawford et al., 1993; Cepeda-Pizarro et al., in press). Most of the species show rapid population growth associated with unusual rains associated with the El Nino-Southern Oscillation (ENSO) (Cepeda-Pizarro et al., in press). Gyriosomus species play an important role by increasing the fragmentation of vegetal detritus (Cepeda-Pizarro, 1989), and are an important trophic resource to numerous vertebrates (Crawford et al., 1993) such as the lizard Callopistes palluma Molina, the black-faced ibis Theristicus caudatus (Gmelin), the seagull Larus modestus (Tschudi) (J. Pizarro-Araya, pers. obs.), and the fox Pseudalopex culpaeus Molina (Pena, 1959).
In this paper we describe two new species of Gyriosomus, with distributional and habitat records and include these in the most recent key for the genus.
Type specimens are deposited in the following collections: FMNH (Field Museum of Natural History, Chicago, USA), IADIZA (Instituto Argentino de Investigaciones de las Zonas Aridas, Mendoza, Argentina), JEBC (Juan Enrique Barriga Private collection, Curico, Chile), LEULS (Laboratorio de Entomologia Ecologica, Universidad de La Serena, La Serena, Chile), MACN (Museo Argentino de Ciencias Naturales Bernandino Rivadavia, Buenos Aires, Argentina), MNNC (Museo Nacional de Historia Natural, Santiago, Chile), NHMB (Natural History Museum, Basel, Switzerland), OSUC (Ohio State University, Columbus, USA), UCCC (Universidad de Concepcion, Concepcion, Chile), and USNM (National Museum of Natural History, Smithsonian Institution, Washington, DC, USA). Body length was measured dorsally, along the midline, from anterior margin of labrum to elytral apex. Drawings were made with a camera lucida adapted to a stereoscopic microscope.
Gyriosomus granulipennis, new species
Figs. 1, 3, 5
Description. Length 17-24 mm. Disc of pronotum and elytra shiny black (Fig. 1); lateral parts of pronotum, pseudopleuron, head, ventral surface, antennae, and legs dull black. Head. Frons with a tuft of setae on inner dorsal margin of eyes. Antennomere 11th with apical tomentose sensory patches on distal 3/4. Thorax. Pronotum glabrous; disc of pronotum shiny black, convex, at lower level than elytra, with one crescent shaped depression in posterior half, with deep wrinkles not reaching anterior margin but reaching posteriorly to the crescent depression; wrinkles of disc rugose in male, in female forming a parabola; lateral parts of...