A new species of Dendrocerus (Hymenoptera, Megaspilidae) from southern Brazil

Abstract A new species of the megaspiline genus Dendrocerus Ratzeburg is described and figured. Dendrocerus riograndensis sp. n., is known from a series of males from the central region of Rio Grande do Sul, Brazil, and were captured with Malaise traps from an agricultural tobacco field.


Introduction
The parasitoid wasp family Megaspilidae includes more than 450 species in 11 ge nera worldwide (Dessart 2006), but the fauna of South America remains little known. Johnson and Musetti (2004) noted the genus Dendrocerus Ratzeburg to be cosmopoli tan, with 96 described species, but only 11 of them are recorded from the Neotropi cal Region. Four species of Dendrocerus are known from Brazil: Dendrocerus sylviae Dessart, collected in Pará State, D. carpenteri (Curtis), collected in many regions of Brazil, D. aphidum (Rondani), recordered in Rio Grande do Sul State and D. phallocrates Dessart, collected in São Paulo State (Dessart and Cancemi 1986;Dessart 1987;Tavares 1996;Dessart 1996;Martinez 2003).
Among species in Dendrocerus males of the halidayi species group are characterized by their flabellate antennae, with long branches on the proximal 4, 5, or 6 flagellom eres. There are 21 species of this group distributed on all continents except Antarctica, with the following four species from the New World tropics: D. araucanus Dessart (Chile), D. mexicali Dessart (Mexico), D. sylviae Dessart (Brazil) and D. ranquel Mar tinez (Argentina) (Dessart 1999;Martinez 2003). The objective of this paper is to describe a new species of Dendrocerus belonging to the halidayi group.

Material and methods
Specimens were collected with a Malaise trap in an organically managed cultivation of tobacco (Nicotinana tabacum L.) during the 2011-2012 crop, in Santa Cruz do Sul, Rio Grande do Sul, Brazil. The material was studied using a stereoscopic microscope trinocular Motic Quimis Q764ZT and is deposited in the Coleção Entomológica de Santa Cruz (CESC).
The morphological nomenclature, format for the description, and measurements employed follow that of Dessart (1999), while Martinez (2003) is followed for features of the flagellomeres and side branches. The relative measures, except the entire body length, are expressed in millimeters.

Dendrocerus riograndensis Pezzini & Köhler, sp. n. http://zoobank.org/F2786CA16E1C48608A4DE34368737B16
Etymology. The specific epithet is based on the state of Rio Grande do Sul from where the type series was captured.
Diagnosis. Male head moderately transverse; antenna with five rami on first to fifth flagellomeres (antennomeres three through seven), not articulated, remaining flagellomeres without rami. Mesoscutellum without grooves or lateral carina; propo deum without armature. Metasoma smooth and shining, without punctures.
Wings: Forewing without cells, marginal vein long and pubescent, membrane with numerous microtrichia, pterostigma well developed (as in all species of the family), 0.12 mm diameter, poststigmal veins well defined and long (Fig. 5); no other veins present, hind wing without venation.

Biology. Unknown.
Comments. The number of lateral rami on the antenna, the dimensions of each flagel lomere (length × width), and the form of the forewing veins serve to distinguish D. riograndensis sp. n. from the other species of the halidayi species group. Dendrocerus sylviae belongs to the halidayi group, but only the female is known, separated from the other species by the possession of longitudinal grooves on T III .
Distribution. Dendrocerus riograndensis sp. n. is known presently only from the central region of Rio Grande do Sul, Brazil. Future surveys will be needed in order to better ascertain its total potential distribution.       Antennal branches relatively thin; A 7 and A 8 of similar width; R 1 smaller than R 2 ; R 5 length approximately similar to A 7 (Fig. 3) ....................... D. ranquel Antennal branches relatively thick; A 7 thinner than A 8 ; R 1 and R 2 of same length; R 5 much longer than A 7 (Fig. 4)