Redescription of the Neotropical species Trichodischia soror Bigot, 1885 (Diptera: Tachinidae), with a new generic synonymy

. Trichodischia Bigot, 1885 is a Neotropical genus with a confusing taxonomic history. This was initially composed of two species: T. caerulea Bigot, 1885 and T. soror Bigot, 1885. Later, the genus Trichoraea Cortés, 1974 was erected for T. caerulea. When reviewing the taxonomic history of both species, we discovered that both genera have been considered synonymous based on erroneous information and without a formal synonymy being proposed. Herein, we redescribed T. soror, provide images of adults and describe the male terminalia for the first time. In addition, by examining the type material, we propose Trichoraea as a junior synonym of Trichodischia, syn. nov. , confirm T. caerulea comb. rest. and T. soror as valid species and provide some comments about the taxonomy and host record of the genus.


INTRODUCTION
Trichodischia Bigot, 1885 is a Neotropical genus belonging to the tribe Voriini and subfamily Dexiiinae (Tachinidae) . This genus was originally composed of two species: T. caerulea Bigot, 1885 andT. soror Bigot, 1885; both species with a complex and confusing taxonomic history. Brauer (1898) was the first revisor redescribing both species and providing some taxonomic notes. Cortés (1944) synonymized both species, letting just T. caerulea as valid. Later, Cortés (1969) revalidated T. soror and provided a diagnostic key for both species; with the most conspicuous difference being the dark metallic blue color of scutum and abdomen in T. caerulea, whereas T. soror presents the scutum and abdomen brownish black. Lastly, Cortés (1974) changed his mind and considered T. caerulea as belonging to a distinct genus from Trichodischia, erecting the genus Trichoraea Cortés, 1974 for this species.
In the same way, the validity of the genus Trichoraea remained unclear. The matter begins when Guimarães (1977) wrongly catalogued Trichodischia caerulea as a parasitoid of Spodoptera frugiperda, relying on the work of Blanchard (1963). There is no way of knowing if this error was caused by some distraction when cataloging the name of the species or by ignorance of the work of Cortés (1974), who, in addition to creating the genus Trichoraea, also concluded that the specimen cited by Blanchard (1963) was actually T. soror. This error led more authors (e.g., Henry, 1987; to wrongly cited the species as Trichodischia caerulea instead of Trichoraea caerulea, and the genus Trichoraea was assumed as synonym of Trichodischia without any formal proposition of synonymy (e.g., . The systematic placement of Trichodischia also changed along the years; it was first classified in the tribe Macquartiini in Dexiidae (Dexiinae in part) by Townsend (1936), position roughly maintained by Guimarães (1971). However, in O'Hara et al. (2020, this genus was moved to Voriini, alongside most of the Neotropical genera of Macquartiini.
Herein, to clarify this confusion, we redescribe the type species of genus Trichodischia, T. soror, presenting for the first time a full description and illustration of the male terminalia. We also synonymized Trichoraea under Trichodischia, confirm T. caerulea comb. rest. and T. soror as valid species, and provide some comments about the taxonomy and host record of the genus.

MATERIAL AND METHODS
The type material examined of T. caerulea (Lectotype) and T. soror (Holotype) is deposited at the Natural History Museum (NHMUK). The additional material used for the redescription of T. soror is deposited at the Diptera collection of the Museu de Zoologia da Universidade de São Paulo (MZSP) and at the Museu Nacional, Rio de Janeiro in Brazil (MNRJ). Morphological terminology follows Cumming & Wood (2017).
For the study of terminalia, the abdomen was dissected from the fourth segment. To digest tissues and clarify structures, the terminalia were placed in a 10% KOH solution and heated in boiling water for 10 minutes, neutralized in a 5% acetic acid solution and rinsed with distilled water. After examination, the dissected parts were placed in glycerin inside plastic microvials and pinned with their respective specimens.
Photographs of the pinned specimens and terminalia were taken using a Leica MC170 HD digital camera attached to a Leica MZ16 stereomicroscope, and the Leica LAS software version 4.12.0. The images were subsequently stacked with the software Helicon Focus 6.7.1, and then edited in Adobe Photoshop CC 2020. The plates were made with Adobe Illustrator CC 2019.

Diagnosis
Trichodischia differs from other Neotropical Voriini by the following combination of traits: eye setulose, male with strong orbital setae; parafacial with setulae throughout its whole extension; long prementum, equal to the head height; patch of long and hairs-like setulae on the midventral surface of the hind femur in males; tergites 3 and 4 with a pair of discal setae.

On the taxonomic status of T. caerulea comb. rest. and T. soror
The confusing taxonomic history of this species, as aforementioned in the introduction, can be clarified herein. Following the generic diagnosis given below, both species share a considerable number of relevant traits that confirm them as belonging to Trichodischia. At the same time, T. caerulea comb. rest. and T. soror present several traits that provide evidence that both species are valid and differ from each other. The key provided by Cortés (1969) and the analysis of type material of both species by the second author provide the conclusive evidence for this claim. Hence, the following diagnostic key to species, a translation and adaptation of Cortés (1969) that contains the evidence discussed, is given: References: Cortés (1974: 37, new combination and taxonomic notes).
Type locality: Argentina, Buenos Aires.    Avulsos Zool., 2021;v.61: e20216164 4/7 lose, closed dorsally; posterior epandrial process small and moderately acute; anterior epandrial process triangle-shaped with posterior margin curved; lower lateral margin with developed lobe partially covering the surstylus. Hypandrium with long, up curved and arms not fused; hypandrial apodeme well developed, longer than width, and slightly bowl-shaped. Cerci not fused, tapering distally, with straight inner margins and oblique outer margins in posterior view; beak-shaped distal end in lateral view. Surstylus broad, subtriangular with rounded end in lateral view; medially widened and with hook-shaped distal end in posterior view. Phallapodeme slightly arched, extending a little beyond the hypandrial apodeme; phallic guide short. Basiphallus robust and tube-shaped, projecting into a claw-shaped epiphallus. Distiphallus with ventral sclerite longer than dorsal sclerite; ventral sclerite with distal end dorsally fused; membranous region connecting the distal ends of dorsal sclerite and ventral sclerite. Pregonites subrectangular in lateral view, not fused with each other, basal region slightly expanded and fused with medial plate of hypandrium. Postgonites not fused, narrow and claw-shaped, located dorsolaterally to basiphallus, extending almost until apex of distiphallus.

Female (Figs. 3A-F)
Similar to male, but with a pair of proclinate orbital setae, and hind femur without the ventral patch of hairslike setulae.

Remarks
As argued earlier, in his host-parasite catalogue, Guimarães (1977) uses the host record derived from Blanchard (1963), that recorded T. caerulai (sic) from Spodoptera frugiperda. This information was followed by some subsequent authors (e.g., Virla et al., 1999;Molina-Ochoa et al., 2003). However, these authors overlooked the observations of Cortés (1974) that concluded that the real T. caerulea was misidentified by Blanchard; in reality, he had a T. soror specimen. Hence, all these host records for Trichodischia are from T. soror only. Furthermore, Cortés (1974) believed that the species of Trichodischia treated as new by Parker (1953), and as T. caerulea by Parker et al. (1953), are in reality T. soror.

AUTHORS' CONTRIBUTIONS
Deivys Alvarez-Garcia: Conceptualization, Investigation, Visualization, Writing -original draft, Writing -review & editing. Marcelo Santis: Investigation, Visualization, Writing -review & editing. All the authors actively participated in the discussion of the results, they reviewed and approved the final version of the paper.