New gall midges ( Diptera , Cecidomyiidae ) associated with Eugenia uniflora and Psidium cattleianum ( Myrtaceae )

Two new species and a new genus of gall midges (Diptera, Cecidomyiidae) are described and illustrated. Both species induce leaf galls on Myrtaceae, the former on Eugenia uniflora and the latter on Psidium cattleianum.


PALAVRAS-CHAVE.
Eugenia uniflora (Myrtaceae) is popularly known as pitangueira.It occurs in Brazil (from Bahia to Rio Grande do Sul), Uruguay, Paraguay, and Argentina (MARCHIORI & SOBRAL, 1997).Its fruits are eatable and used in the manufacturing of soft drinks and jelly.
Only three gallers are identified at specific level, the others remain at family level.In this paper, the inducer of the triangular leaf galls is identified as a new species of Eugeniamyia Maia, Mendonça & Romanowski, 1996 which is described and illustrated (male, female and larva).
Eugeniamyia was known, until this moment, from one species, E. dispar Maia, Mendonça & Romanowski, 1996, which induces leaf galls on Eugenia uniflora.This genus has a very peculiar male terminalia (MAIA et al., 1996(MAIA et al., , fig. 7, p.1089)); ovipositor short, barely protractible, and separate female cerci with strong setae at the apex and otherwise covered with sparse setae.These characters are also presented by the new species.
Psidium cattleianum (Myrtaceae), popularly known as araçá, is native to the Atlantic forest of southeastern Brazil, extending from the state of Espírito Santo in Brazil to Uruguay (20-32ºS) (MARCHIORI & SOBRAL, 1997;REITZ et al., 1983).Although not cultivated commercially on a significant scale, P. cattleianum has been cultivated for its fruit and ornamentally.It is also a popular fuel wood (HODGES, 1988).
A new genus and species of midge that induces cylindrical leaf galls on P. cattleianum was found in Rio Grande do Sul.This galler is also described herein (male, female and pupa).It belongs to the supertribe Lasiopteridi, but it does not fit in any known tribe.

MATERIAL AND METHODS
Triangular galls on leaves of E. uniflora were collected in August, 2000 in the restinga of the Barra de Maricá, Maricá, southern, Brazil.To obtain adults, part of the samples was taken to the laboratory and kept in plastic pots layered at the bottom with restinga soil (as the larvae drop to the soil and pupate on the ground) covered by a fine screening.
Cylindrical leaf galls on P. cattleianum were collected in December, 2008 andJanuary, 2009 in Pelotas, southern, Brazil.The samples were placed in plastic bags and transported to the laboratory, where some galls were dissected under a stereoscopic microscope to obtain immature stages of the galling insect.Adults were obtained by keeping some samples in plastic pots (300 ml) layered at the bottom with a 1cm solution 5% agar/ water and covered by a plastic film.All pots were daily checked to verify galler emergence.Larvae, pupae and adults were preserved in 70% alcohol.
The specimens were prepared and mounted on slides following the methods of GAGNÉ (1994).All material, including the types, are incorporated in the Diptera collection of Museu Nacional, Rio de Janeiro (MNRJ).Terminology of the adults follows MCALPINE (1981) and that of the immature stages follows GAGNÉ (1989).
Remarks.The adults of E. triangularis differ from those of E. dispar mainly in the number of flagellomeres (12-14 in the former and 14-18 in the latter), wing venation (M3 and CuP present only in the new species), shape of gonostylus (more curved in the E. triangularis), width of male hypoproct and male cercal lobes (both are slender in the new species).The larvae of both species are very distinct, differing in the shape of the larval spatula (twotoothed in the new species and without apical teeth in E. dispar) and number of terminal papillae (two in the new species, and eight in E. dispar).Elachypalpus gen.nov.
Etymology.The name Elachypalpus is composed by elachys (= short) + palpus.It refers to the length of the palpi.
These unplaced genera were previously included in the tribe Oligotrophini, which was a heterogeneous assemblage with no apomorphic character.GAGNÉ ( 2004) redefined this tribe, limiting it to four genera and 16 species associated with Cupressaceae, all with simple tarsal claws with very long empodia (none of them occur in the Neotropical region).
Elachypalpus will key to Haplopalpus in couplet 35 of the Gagné key to genera of Neotropical Lasiopteridi (GAGNÉ,1994), but it differs from it as Haplopalpus has bowed, two-toothed tarsal claws, elaborate pupal antennal horns and female cerci without modified setae.
Among all Neotropical unplaced genus of Lasiopteridi, the female of Elachypalpus resembles that of Eugeniamyia as both present short, barely protractible ovipositor, and separate female cerci with strong setae at the apex and otherwise covered with sparse setae.But, the cerci of the new genus are accentually longer than those of Eugeniamyia (0.11 mm and 0.03 mm, respectively).Furthermore, the male terminalia of both gallers are quite different (see Figs 5,14), as well as the larval prothoracic spatula, which is reduced in the new genus.