Neoethilla, a new genus for the first record of the Ethillini from the New World (Diptera, Tachinidae, Exoristinae)

Abstract New genus Neoethilla gen. n., is described to include two New World nominal species formerly recognized as valid species in Winthemia Robineau-Desvoidy: Exorista ignobilis van der Wulp and Winthemia antennalis Coquillett. Winthemia antennalis is proposed as a junior synonym of Exorista ignobilis syn. n. Neoethilla ignobilis comb. n. is removed from the Winthemiini and placed in the tribe Ethillini (Exoristinae) based on a study of the external features of adults, male terminalia, female reproductive system, and egg morphology. The small tribe Ethillini, not hitherto known from the New World, currently comprises fourteen genera worldwide. The phylogeny and systematics of the Ethillini and their relationships with related tribes are discussed and documented by descriptions and illustrations of relevant character states.

introduction Van der Wulp (1890) described Exorista ignobilis from Guerrero, Mexico, based on a single male. The species was subsequently moved to Winthemia Robineau-Desvoidy, 1830, by Reinhard (1931) and has continued to be treated as a valid species of Winthemia to the present day (Guimarães 1972). However, Reinhard (1931) misidentified the species; he did not examine the holotype of E. ignobilis but instead relied on notes taken of it by J.M. Aldrich in 1929. Based on these notes, Reinhard (1931) misidentified three specimens from Chile and Argentina as Winthemia ignobilis and redescribed the species from this material. Aldrich (1934) himself accepted the identifications of Reinhard (1931) and included the species under the same combination in his faunal treatment of the Tachinidae of Patagonia and South Chile. Cortés and Hichins (1969) also recognized a Chilean species of Winthemia as W. ignobilis. Although the identities of these specimens from Chile and Argentina have yet to be clarified, we suspect that everything once called W. ignobilis from these countries is W. reliqua Cortés & Campos, 1971.
A second nominal species, Winthemia antennalis, was later described by Coquillett (1902) based on a single female from Los Angeles County, California, United States. Coquillett (1897) had earlier misidentified this single specimen as Winthemia nigrifacies (Bigot, 1889) in his key to the species of Winthemia of America north of Mexico. Tothill (1912) continued the placement of this species in Winthemia in his key to the North American species of the genus, as did Reinhard (1931) in his revision of the "American" species of Winthemia. This classification was also followed by Sabrosky and Arnaud (1965) in the Catalog of the Diptera of America north of Mexico. Guimarães (1972), however, removed W. antennalis from Winthemia in his revision of the Winthemia of America north of Mexico. Without further explanation, he wrote in his abstract: "Winthemia antennalis Coquillett does not belong in this genus and its correct placement has not been determined" (Guimarães 1972: 27). Sabrosky (1973) apparently agreed, as he did not include W. antennalis in his paper on the identification of Winthemia species of America north of Mexico.
Winthemia antennalis was again treated as a Winthemia species, albeit provisionally, by Wood (1987). Wood (1987Wood ( : 1210 explained this placement in a footnote: "Although arrangement of postpronotal bristles is different from other species of Winthemia, the male terminalia and unembryonated planoconvex egg suggest a relationship, which may ultimately be resolved by additional study of the tribe Winthemiini". Recently, O'Hara and Wood (2004) maintained this classification and listed W. antennalis under Winthemia in their catalogue of the Tachinidae of America north of Mexico.
The enigmatic placement and identity of E. ignobilis and W. antennalis became a topic of discussion among us when several specimens provisionally identified as W. antennalis were collected in the Gila National Forest of New Mexico, United States, during the field meeting of the North American Dipterists Society in 2007. Upon further study we have determined that W. antennalis Coquillett is a junior synonym of E. ignobilis van der Wulp and that this taxon belongs not to the Winthemiini but to the Ethillini, a tribe hitherto unknown from the New World. We discuss below the characteristics of the Ethillini and propose a new genus for the single known New World species of this tribe.

Specimens
Male terminalia of Neoethilla ignobilis were dissected following the method described in detail by O'Hara (2002), then dehydrated with ethanol and critical point dried. After examination, the terminalia were rehydrated and preserved in glycerine in a plastic microvial pinned below the specimen (cf. Cerretti and Shima 2011). One egg, almost entirely exposed but still attached to the ovipositor of a dried female of N. ignobilis from Plymouth, Massachusetts (CNC), was removed by tilting it carefully with a pin and then mounted on a micropin. After ESEM examination the egg was glued on a tag and pinned below the source specimen. Male terminalia, pinned specimens and egg were examined, uncoated, with a Hitachi TM1000 environmental scanning electron microscope (ESEM); male terminalia were also slide mounted and examined with a Leica DMLS. Figures 1a-e were prepared from composites of images captured using a Canon EOS 40D Digital SLR camera body, with a Canon MP-E 65mm 1-5X macro lens, mounted on a Kaiser RS1 copy stand (for further details see O'Hara 2012); figures 5a-c were prepared from composites of images captured with a Nikon Digital Sight DS-L1, DS-5M mounted on a Leica DMLS. Specimens examined are preserved in the following collections (acronyms used in the text): Label data of the holotypes of E. ignobilis and W. antennalis are cited verbatim with the end of lines and labels indicated by the following symbols: /, end of a line and beginning of the next; //, end of a label and beginning of the next (from top to bottom on the same pin).

Terminology
Morphological terminology generally follows McAlpine (1981), except for the antenna and a few details of thoracic chaetotaxy for which we are following Stuckenberg (1999) and Tschorsnig and Richter (1998), respectively. Measurements and ratios of the head follow Cerretti (2010 Description. This generic description is based on a redescription of the single included species, N. ignobilis. Length: 5.5-7.5 mm. Colour: Head mainly black, covered with grey microtomentum. Palpus black to brown (usually paler in female). Thorax and legs entirely black. Abdomen mainly black but reddish yellow laterally ( Fig. 1a-b). Tegula and basicosta black.
Legs: Preapical anterodorsal seta of fore tibia about as long and stout as preapical dorsal seta. Mid tibia with 1 anterodorsal seta. Hind tibia with a row of moderately spaced, comb-like anterodorsal setae (Fig. 2e); 2 dorsal preapical setae. Preapical posteroventral seta of hind tibia not differentiated. Claws about as long as fifth tarsal segment in male (Fig. 2f), considerably shorter in female.
Wing (Figs 1a-d, 2d): Bend of vein M usually obtuse. Cell r 4+5 open. Section of M between crossveins r-m and dm-cu longer than section between dm-cu and bend of M. Section of M between dm-cu and bend of M shorter than post-angular section of M. Vein R 4+5 with a single setula at base dorsally and 0-1 ventrally. Lower calypter large and strongly convex, especially along its lateral and posterior margins (Fig. 2d).
Abdomen (Fig. 1a-d): Syntergite 1+2 with mid-dorsal depression extending to hind margin. Tergites 1+2 and 3 with a pair of fine median marginal setae, sometimes not differentiated from the general abdominal setae, and a pair of lateral setae; tergite 4 with a row of marginal setae; tergite 5 with scattered weak setae. Tergites 3 and 4 without median or lateral discal setae.
Female terminalia. Ovipositor short, not telescopic as in Winthemiini.
Remarks. Neoethilla is superficially similar to Winthemia because it has an enlarged compound eye covered with thick and long ommatrichia and parafacial covered with fine setulae. Moreover, Neoethilla and Winthemia both have a short first postsutural supra-alar seta, a comb-like row of anterodorsal setae on hind tibia and a fully setulose katepimeron. Neoethilla is distinguishable from Winthemia (i) in having the three strongest basal setae of postpronotum arranged in a line, (ii) in lacking the lateral scutellar setae and (iii) in having processi longi of male terminalia long, slender and well separated from each other. Females of Neoethilla have a short ovipositor and a dorsally operculate plano-convex egg. These characters, together with the strongly convex lower calypter, suggest that Neoethilla has an ethilline affiliation. Within this tribe the new genus is characterized by the following combination of character states: (i) parafacial fully setulose, (ii) gena very narrow (0.10-0.15 times as high as compound eye), (iii) ocellar setae absent or very reduced, (iv) three strongest basal postpronotal setae arranged in a line, and (v) lateral scutellar setae missing.  (

Discussion
The Ethillini are a small tribe of Exoristinae formerly thought to be exclusively Old World in distribution. Most Ethillini share a number of character states with several members of Winthemiini but the relationships between these tribes remain unclear as they have not been investigated with a rigorous cladistic approach. The tribe can be defined by the following character states: (1) Lower calypter strongly convex (Fig. 2d) -this is a very rare condition in the Tachinidae (as well as in other Calyptratae) and could arguably be considered apomor-phic. Excluding Mycteromyiella Mesnil, 1966 andCalliethilla Shima, 1979, whose systematic placements in Ethillini are questionable (see also Crosskey 1984;Shima 1979;Cerretti 2012), all the other ethilline taxa share this character state. Interestingly, a very convex lower calypter is also present in a few species of Winthemia. This could easily be interpreted as convergence if not for the fact that Winthemiini also share other character states with Ethillini (see below), (2) katepimeron usually entirely covered with fine setulae -within the subfamily Exoristinae this character state is shared with practically all known Winthemiini, a few Exorista and the exoristine genus Crassicornia Kugler, 1980(cf. Cerretti et al. 2012Cerretti 2012). Important exceptions exist for Atylomyia Brauer, 1898 and a few Amnonia Kugler, 1971 where the katepimeron is often entirely bare, and (3) female ovipositor short (i.e., non-telescopic) -this could be a plesiomorphic condition compared to the long and telescopic one present in all Winthemiini.
In addition to the above states, all examined female ethillines have a macrotype plano-convex egg of white color. All the Exoristinae, most Phasiinae and the Eutheriini also have a plano-convex egg, or at least traces of a primitive planoconvex shape. This type of egg thus represents a plesiomorphic condition for Ethillini. It is worth noting that Ethillini show two reproductive strategies (Tschorsnig 1988): females with a short ovisac that lay unincubated eggs and females with a long ovisac in which eggs are stored until embryogenesis is complete (Paratryphera-group, see below).
The grasshopper parasitoids Gynandromyia and Phorocerosoma and the genus Zelindopsis (Phorocerosoma-group) share the following: postpronotum with five setae, with the three basal strongest arranged in a triangle; female sternites 4-6 very large and exposed from the ventrolateral margins of the corresponding tergites; and egg surface dorsally smooth with two aeropilar areas, irregular in shape. The number and disposition of postpronotal setae are exactly the same as in nearly all the Winthemiini, and the egg characteristics are shared with several other Exoristinae. However, the features of the female abdominal sternites appear to be unique within the Exoristinae and may represent a strong apomorphy in support of the monophyly of this group of ethilline genera. Interestingly, males of Mycteromyiella share with males of several species of the Phoroserosoma-group the presence of distinctive spots of setulae and microtrichia on the ventral side of abdominal tergites 4 and 5, and also its members are parasitoids of Phasmatodea (Shima 1976), which are currently considered the living sister-group of the Orthoptera (cf. Grimaldi and Engel 2005).
The presence of operculate eggs is a very rare condition in tachinids. In most Exoristini an operculum is delineated by a line at the anterior end of the egg (cf. Wood 1972;Cerretti 2010), in Eutherini an oval "window" is situated on the dorsal surface of the egg immediately in front of its posterior end (Herting 1966), while in Ethillini s. str. an operculum is situated on the dorsal surface of the egg in its anterior half or in the middle (cf. Tschorsnig 1988;Tschorsnig and Richter 1998). Such substantial differences in the shape and position of the operculum in these groups suggest that the three types may have evolved independently and thus be non-homologous. Based on the four states listed here we consider the Ethillini s. str. to be a monophyletic lineage.
We transfer the New World species Exorista ignobilis van der Wulp to the Ethillini and assign it to the new genus Neoethilla based on its distinctive characteristics. Neoethilla may share a sister-group relationship with Prosethilla, as evidenced by its lack of lateral marginal setae on the scutellum and similar egg morphology (operculum, microsculpture and shape very similar in these genera, judging from figures of Prosethilla by Tschorsnig (1988)). Neoethilla is clearly distinguishable from Prosethilla by its very large compound eye that occupies most of the head in lateral view (gena very narrow, compared to 1/3 or more of vertical eye height in Prosethilla), parafacial entirely covered with fine setulae (as in Winthemia), and ocellar setae not (or just slightly) differentiated from other setulae on the ocellar triangle.