Yungahelea , a new genus of predaceous midge from northwestern Argentina ( Culicomorpha : Ceratopogonidae )

A new monotypic genus and species of predaceous midge from the southernmost area of the Argentinean Yungas, Yungahelea australis Spinelli and Ronderos, is described and illustrated from male and female adults. It belongs to a group containing the Ceratopogonini genera Parabezzia Malloch, Diaphanobezzia Ingram and Macfie, Spinellihelea Borkent, Grogan and Picado, Leptohelea Wirth and Blanton, and Fittkauhelea Wirth and Blanton. Phylogenetic interpretation indicates that Yungahelea is the sister group of Spinellihelea or the clade composed by Parabezzia and Diaphanobezzia.


INTRODUCTION
A recent survey of ceratopogonids in the Yungas of the Tucumán province in northwestern Argentina revealed the presence of males and females of a species which could not be placed within any of the hitherto recognized genera in the family.The species clearly belonged to a small group of genera of Ceratopogonini representaed by Parabezzia Malloch, Spinellihelea Borkent, Grogan and Picado, Diaphanobezzia Ingram and Macfie, Fittkauhelea Wirth and Blanton, and Leptohelea Wirth and Blanton.This group of genera, mostly distributed in the Neotropical region, was reviewed by Borkent et al. (2008) on the basis of morphological characters, being this publication the only antecedent in the literature dealing with its phylogeny.
The purpose of this paper is to describe the new genus and species and to interpret its cladistic relationships to related genera.

MATERIALS AND METHODS
All specimens were slide mounted in Canada balsam and examined and measured with a binocular compound microscope.Photomicrographs were taken with a digital camera Micrometrics GUSTAVO R. SPINELLI et al.
SE Premium, through a Nikon Eclipse E200 microscope and a Nikon SMZ 1000 stereoscopic magnifying.Terms of structures follow those used in the Manual of Central America Diptera (Brown et al. 2009).
In order to establish the phylogenetic relationships of the new genus Yungahelea, a cladistic analysis was performed using the character setting of Borkent et al. (2008) with some modifications that are shown below.Using more inclusive synapomophies as argument, the terminals chosen for this analysis were the genera Parabezzia, Spinellihelea, Diaphanobezzia, Fittkauhelea, and Leptohelea, those belonging to the Spinellihelea clade within the tribe Ceratopogonini of the cladogram made by Borkent et al. (2008).The resulting data matrix of 11 characters and 7 taxa is shown in Table I.The genus Bahiahelea Wirth was selected as outgroup since it is one of the two sister groups of the Spinellihelea clade in the phylogenetic analysis of Borkent et al. (2008) and belongs to the Neotropical region.
Data matrix was analyzed in the program TNT version 1.1 (Goloboff et al. 2008) applying implied weights as optimality criteria.A TNT script (propk.run) written by Salvador Arias was used to calculate the appropriate value for constant k.After running the script, a value of k=3 was obtained for our data set and was selected for data analysis.To obtain the most parsimonious cladogram, an exact solution was applied.Character support was estimated with absolute and relative Bremer support values.
The specimens examined, that include species of all analyzed genera except Leptohelea, are deposited in the collection of the Museo de La Plata, Argentina (MLPA).For diagnoses of the involved genera see Wirth and Blanton (1970), Grogan and Wirth (1977), Wirth and Grogan (1988), Wirth (1992) and Borkent et al. (2008), and characters on the male wing and male genitalia of Leptohelea may be found in Borkent and Spinelli (2007).
Diagnosis.Male: the only genus of Ceratopogonidae with the following combination of features: eyes bare, widely separated, palpal segments 4 and 5 fused and long as segment 3, wing with bunch of 9-11 stout, appressed setae proximad to basal arculus, anterior margin bent where R 3 ends, with one radial cell and M 2 forking distal to r-m, halter with narrow stem and bulbous knob, coxae without long stout setae, tibiae very spinose, hind leg first tarsomere with strong basal spine and single row of ventral palisade setae, tergite 9 with a posteromedial notch, parameres fused medially, well developed.Female: the only genus of Ceratopogonidae with the following combination of features: eyes bare, widely separated, palpal segments 4 and 5 fused and long as segment 3, clypeus fused with ventromedial margin of eye, wing with one large radial cell, costal extension relatively short and M forking distal to r-m, halter with narrow stem and bulbous knob, legs lacking armature, sternite 9 separate medially.
Taxonomic discussion.Yungahelea belongs to a group containing the following four Ceratopogonini genera: Parabezzia, Diaphanobezzia, Spinellihelea, and Fittkauhelea.In these genera the palpus is reduced to four segments due to a fusion of segments 4 and 5, the costa does not extend beyond the apex of the radial cell in the male wing and the male parameres are absent or very reduced, or they are fused forming a flat medial structure.
Due to its well developed parameres, Yungahelea is apparently most similar to Parabezzia and Diaphanobezzia, but in these genera the male forecoxa bear several stout and markedly developed setae; Diaphanobezzia also differs from this new genus by the peculiar sac-like halter.Due the presence of normally developed setae in the male forecoxa and the anterior margin of the male wing bent where R 3 ends, Yungahelea is very similar to the recently described genus Spinellihelea from Costa Rica, but in the latter the female claws lack basal inner tooth and the male tibiae, especially the hind one are slender and bear normally developed setae.
Etymology.The name Yungahelea, gender feminine, is related to the Yunga ecoregion where the specimens here described were collected.
Distribution.Yungahelea australis is known only from the type locality.Specimens were collected using sweep nets at 656 m of altitude, in one of the

DISCUSSION
The most recent phylogenetic analysis of the Ceratopogonini was performed by Borkent et al. (2008), where the clade of interest in this study showed a basal trichotomy formed by the clades (Parabezzia, Diaphanobezzia), (Fittkauhelea, Spinellihelea), and the genus Leptohelea.The first clade supported by the synapomorphy male forecoxa with markedly developed, stout setae, and the second one supported by the synapomorphy male parameres fused forming a flat medial structure.
In our study, the inclusion of the new genus Yungahelea modified the phylogenetic relationships performed by Borkent et al. (2008) From the cladograms found in our analysis, two main groups could be distinguished, cladograms 24a and 24b showing Yungahelea as the sister group of (Parabezzia, Diaphanobezzia), and cladogram 24c and 24d showing Yungahelea as the sister group of Spinellihelea.As was mentioned above, the former relationship is supported by the character male parameres fused forming a flat medial structure [10 (3)].It is important to point out that the character state male parameres very reduced or absent [10 (2)] is shared by Spinellihelea and Fittkauhelea and represents a synapomorphy in the cladogram elected as reference, but was not enough to put together those genera.Instead, the inclusion of the new genus in the Ceratopogonini changed the character interpretation.The new combination of characters plus the finding of a new synapomorphy that is the anterior margin of male wing bent where R 3 ends [6 (0)], forced the displacement of the genus Fittkauhelea to a basal position becoming therefore more closely related to Leptohelea.
Finally, the new genus exhibits a bunch of 9-11 stout, appressed setae proximad to basal arculus which are separated from the costal fringe by a short distance, and the apex of tergite 9 notched mesally, being these two characters autapomorphies that reinforces the erection of Yungahelea as a new genus.
, since that genus became the sister group of Spinellihelea and placed Fittkauhelea in a more basal position.