Review of the genus Euantha Wulp, 1885 (Diptera: Tachinidae), with key to species and redescription of E. pulchra Wulp, 1891

Abstract

Euantha Wulp is a New World genus in the tribe Sophiini (Dexiinae). It includes three species: E. interrupta Aldrich, 1927, E. litturata (Olivier, 1811) and E. pulchra Wulp, 1891. This last species is poorly known, being restricted mostly to catalogues since its original description. Here E. pulchra is redescribed, a lectotype is designated and the male is diagnosed for the first time. In addition, this species (originally described from Mexico) is newly recorded from Guatemala. Finally, the first key to include all the species of Euantha is provided.

Key words
Dexiinae; neotropical; Sophiini; taxonomy

INTRODUCTION

The New World tribe Sophiini is composed of 22 species allocated in nine genera, namely Cordyligaster Macquart, 1844; Cryptosophia Santis 2018; Euantha Wulp 1885; Euanthoides Townsend, 1931; Leptidosophia Townsend, 1931; Neosophia Guimarães 1982, Neoeuantha Townsend, 1931; Sophia Robineau-Desvoidy, 1830; and Sophiella Guimarães, 1982 (Guimarães 1971, 1982, O’Hara et al. 2020). This tribe has been studied recently in three contributions: Fleming et al. (2014) added a new species for Cordyligaster, C. capellii Fleming & Wood, 2014; Santis (2018) provided a key to the genera of Sophiini and described a new genus and species Cryptosophia aurulenta Santis 2018; and Santis & Nihei (2019) described two new species of Neosophia, N. guimaraesi Santis & Nihei, 2019 and N. bispinosa Santis & Nihei, 2019.

This taxonomic study of Euantha is the third part of a series of studies on the tribe Sophiini (see also Santis 2018, Santis & Nihei 2019). Herein these studies are broadened to include this New World genus that includes three species: E. interrupta Aldrich, 1927 (Neotropical: Costa Rica, Panama), E. litturata (Olivier, 1811) (Nearctic: USA; Neotropical: Guatemala, Mexico) and E. pulchra Wulp, 1891 (Neotropical: Guatemala, Mexico). Euantha can be distinguished from other sophiine genera by the keys in Guimarães (1982) and Santis (2018), and by the diagnostic characters given below.

Euantha pulchra is poorly known and has not been studied since its original description from Mexico by van der Wulp (1891). It has only been included in catalogues (Guimarães 1971) and lists (O’Hara et al. 2020), in addition to Guimarães’ revision of the sophiines (1982) as synonym of E. litturata; however, it was not included in any species key and its identity has remained uncertain. In this paper, E. pulchra is redescribed based on the type series and additional specimens, including the male for the first time. A lectotype is designated from among the three existing female syntypes to fix the name to a single specimen in accordance with Article 74 of the Code (ICZN 1999), that pertains to the purpose of fixating the identity of the name to the respective name-bearing specimen, to clarify any taxonomic doubt involving that name. The first identification key for all species of Euantha is also provided.

MATERIALS AND METHODS

The examined material is deposited in the Natural History Museum, London, UK (NHMUK). The label data are presented within quotation marks for each label, with forward slashes indicating line breaks and semicolons separating different labels. Comments about labels, additional information and corrections are given in square brackets. Morphological terminology follows Cumming & Wood (2017).

Photographs of the pinned specimens were taken using a Canon EOS 5DSR and the Helicon Remote 3.9.10. The images were subsequently stacked (merging different focal planes into one image) with the software Helicon Focus 7.5.8.

Euantha Wulp, 1885

Euantha Wulp, 1885: 195. Type species: Dexia dives Wiedemann, 1830 (= Ocyptera litturata Olivier, 1811) by monotypy.

Van der Wulp (1891): 248 (revision); Brauer & Bergenstamm (1893): 128 (in key to his “Minthoidae”); Aldrich (1905): 505 (in key to North American genera); Coquillett (1910): 540 (type species); Townsend (1939): 164 (redescription); Sabrosky & Arnaud (1965): 1030 (catalogue); Guimarães (1971): 111 (catalogue); Guimarães (1982): 163 (in key to Sophiini genera), 164 (generic diagnosis); Wood (1987): 1249 (in key to Nearctic Tachinidae); Sabrosky (1999): 131 (family-group name based on Euantha); O’Hara & Wood (2004): 46 (catalogue); Wood & Zumbado (2010): 1384 (in key to Central American Tachinidae); Santis (2018): 435 (in key to Sophiini genera); O’Hara et al. (2020): 119 (checklist of World Tachinidae); O’Hara & Henderson (2020): 29 (list).

Diagnosis. Euantha is most similar to Neoeuantha within the Sophiini and they both have lower calypter well developed, wing cell r₄+₅ not petiolate, scutellum with pair of strong apical setae, katepisternal with 2 setae, postmetacoxal area membranous, abdominal syntergite 1+2 not conspicuously petiolate and narrow, and tergites 3 and 4 with median discal setae. Euantha differs from Neoeuantha in facial carina present, scutum with acrostichal setae 2+1 or 1+1, and costal spine present (Guimarães 1982, Santis 2018).

Key to species of Euantha

1. Vein R₄₊₅ with long appendage at bend; abdomen predominantly darkened yellow in ground color with tergite 3 to 5 with a narrow band of yellowish pruinosity on anterior margin. .................................................… E. litturata (Olivier, 1811)

- Vein R₄₊₅ without appendage at bend or with a mere trace of one; abdomen brownish black in ground color (Fig. 1b)...................................................… 2

Figure 1
Euantha pulchra Wulp (female, lectotype): a. lateral habitus; b. dorsal habitus; c. head, lateral view; d. head, frontal view; e. labels.

2. Abdominal tergites with silvery pruinose bands interrupted in middle; legs brownish black ..............................… E. interrupta Aldrich, 1927

- Abdominal tergites with silvery pruinose bands on females (Figs. 1b-c) and yellowish on males (Figs. 2a, c), not interrupted in the middle; legs with femur yellowish, only brownish black on about distal ⅛ (Figs. 1a, 2a) ................................................................................................… E. pulchra Wulp, 1891

Figure 2
Euantha pulchra Wulp (male): a. lateral habitus; b. dorsal habitus; c. head, frontal view; d. labels.

Euantha pulchra Wulp, 1891

Euantha pulchra Wulp, 1891: 249. Described from five female syntypes. Lectotype female, here designated. Mexico, Guerrero, Amulango (formerly Amula) (NHMUK).

References. Aldrich (1927): 27 (synonymy with E. litturata); Guimarães (1971): 111 (catalogue, as valid and distinct from E. litturata); Guimarães (1982): 164 (synonymy with E. litturata); O’Hara et al. (2020): 117 (checklist of World Tachinidae, as valid and distinct from E. litturata).

Type material examined. Lectotype female (NHMUK), here designated: ‘♀’; ‘Syn-/type’; ‘Amula,/ Guerrero,/ 6000 ft,/Aug. H. H. Smith’; ‘B.C.A. Dipt. II/ Euantha/ pulchra,/ v.d.W.; ‘Centra America./ Pres. By/ F. D. Godman./ O. Salvin./ B.M. 1903-172.’; ‘Lectotype Euantha pulchra Wulp designated by Santis (2020)’; and a bar code (NHMUK 013933622) was added. Specimen in good condition.

Paralectotypes: two females (NHMUK), same locality data as lectotype, and conspecific with the lectotype. A green label written “Paralectotype” was added to each specimen. Van der Wulp (1891) described this new species based on five female syntypes, that should all be in NHMUK but only three female syntypes were found.

Additional material examined. MEXICO. Guerrero, Chilpancingo, Amula, 6000 feet, 1 male, Smith coll. (NHMUK); Omiltemi, 8000 feet, 1 male, Smith coll. (NHMUK); GUATEMALA. Alta Verapaz, Chiacam, 2400 feet, 1 male, Champion coll. (NHMUK).

Diagnosis. Vein R₄₊₅ without appendage at bend; abdominal tergites with silvery pruinose bands on females, and yellowish on males, not interrupted in middle; legs with femur yellowish, but on about ⅛ on distal region is brownish black.

Redescription of female

Body length: 12.5 mm.

Coloration (Figs. 1a-d) Occiput with silver pruinosity; with long golden setae. Fronto-orbital plate blackish, but external portion, about ¼ silvery pruinose. Parafacial, face and gena silvery pruinose. Genal dilation light brown. Antenna dark brown. Arista light brown. Palpus dark brown. Labellum and prementum dark brown. Thorax laterally dark brown, but silvery pruinosity on anepisterum and katepisternum. Scutum silvery pruinose with two broad brownish black vittae. Postpronotal lobe with silver pruinosity. Scutellum dark brown, but silvery pruinose on distal half. Subscutellum and postnotum dark brown. Tegula and basicosta dark brown. Wing hyaline, but with dark markings on subcostal and costal distal cells and distal portion of cells r₁, r₂₊₃ and r₄₊₅, and darker along the veins. Calypters whitish. Halter with knob dark brown and stalk light brown. Legs dark brown, but coxae with silver pruinosity and femur yellowish, but on about ⅛ on distal region is brownish black. Claws dark brown. Abdomen brownish black, but tergites III and IV with a broad band of white pruinosity on about ¾ of anterior margin, extending down to the sides; tergite 5 with silver pruinosity dorsally.

Head. (Figs. 1c-d) Ocellar setae long, well developed and proclinate. Inner vertical seta decussate, strong, outer vertical seta absent. About 9-10 pairs of frontal proclinate setae, ending before the antenna insertion level. Fronto-orbital plate with 2 proclinate and 1 lateroclinate orbital setae. Parafacial bare. Width of parafacial measured at distance between inner margin of eye and antennal insertion 2.5X the gena height. Postpedicel slender, 1.5X the length of scape and pedicel combined; arista long plumose. Facial carina present. Facial ridge setulose on lower third (near vibrissa insertion). Lower facial margin not protruding, and not visible in profile. Genal height about 2.5X the eye height. Vibrissa long, inserted at level of lower facial margin. About 5 subvibrissal setae. Labella well developed, about half the length of prementum, which is about the same length as palpus.

Thorax. (Figs. 1a-b) Acrostichal setae 3+0 (presutural setae very weak). Dorsocentral setae 5+3. Intra-alar setae 1+2; intra-postalar seta absent. Supra-alar setae 1+2. Postpronotal lobe with 2 setae. Anepisternum with 4 strong setae and none upward directed setulae anteriorly. Katepisternum with 2 setae. Anepimeron with just 1 short setulae. Notopleuron with 2 equal-sized setae. Postalar callus with 2 setae. Propleuron and prosternum bare. Anatergite bare. Meron with 2 setae. Posterior spiracle with posterior lappet equal sized with anterior one. Katepimeron bare. Scutellum with 1 basal, 1 subapical and 1 apical pairs of setae.

Legs. Fore coxa with 5 setae anteriorly; fore femur with dorsal and posteroventral rows of setae; one submedian anterodorsal seta and 1 submedian anteroventral seta, and 4 preapical setae: 1 anterodorsal, 1 posterodorsal and 1 posteroventral and 1 anteroventral. Mid femur with 1 submedian anterodorsal seta, 1 posterodorsal seta on distal third. Mid tibia with 2 submedian seta on posteroventral, 2 anterodorsal setae, 2 posterodorsal setae, and 6 preapicals: 1 dorsal, 1 anterodorsal, 1 posterodorsal, 1 ventral, 1 anteroventral and 1 posteroventral. Hind femur with 1 anterodorsal seta on apical third, 3 posteroventral seta on anterior half, 3 anterodorsal seta on distal third, 1 anteroventral seta on apical third. Hind tibia with 2 submedian anteroventral setae, 2 anterodorsal and 2 posterodorsal setae on submedian, and 6 preapicals: 1 dorsal, 1 anterodorsal, 1 posterodorsal, 1 ventral, 1 anteroventral and 1 posteroventral. Tarsus flattened dorsolaterally (). Claws straight with the tip curved, length shorter than 5th tarsomere.

Wing. () Costal spine present. Base of R₄₊₅ with 2-3 setulae ventrally and dorsally. M bent forward to R₄₊₅, somewhat convex after bend and with a small extension, reaching wing margin separate from R₄₊₅.

Abdomen. (Figs. 1b-c). Syntergite 1+2 with mid-dorsal longitudinal depression extending well before the posterior margin. Syntergite 1+2 to tergite V with a pair of median marginal setae; tergites 3 to 5 with 1 pair of median discal setae; syntergite 1+2 to 3 with 1 pair of median lateral setae; tergites 4 and 5 with a row of marginal setae. Sternites 2 to 4 absent (wholly membranous).

Male. Differs from female by the following. (Figs. 2a-c): without orbitals on the fronto-orbital plate. Postpedicel with proximal half orange and distal half light brown. Head, thorax and abdomen with golden pruinosity. Prescutum pale silvery pruinose, with four brownish black vittae, the outer four times the width of the inner. Scutellum pale golden pruinose. Claws and pulvilli longer than the female.

Biology. Unknown.

Distribution. Mexico (Guerrero) and Guatemala (Alta Verapaz). New record from Guatemala.

Remarks. In the same work, van der Wulp (1891) additionally recorded two males and six females as Euantha dives (Wiedemann, 1830) [(=E. litturata (Olivier, 1811)]. However, MDS’s examination of Wulp’s material at NHMUK revealed that three males identified as Euantha dives by Wulp are, in fact, males of E. pulchra and are treated as such herein. Furthermore, Aldrich (1927) also noticed that van der Wulp (1891) wrongly mistook some males of E. dives (=E. litturata) as females, having concluded that E. pulchra would be a synonym of E. litturata, a position also maintained by Guimarães (1982). While it is confirmed herein that Wulp mistook the gender of those specimens, the synonymy cannot be maintained. Guimarães (1971), and later O’Hara et al. (2020) treated E. pulchra as valid, but Guimarães (1982) listed it as a synonym of E. litturata without giving an explanation for this change in status. However, based on our comparisons with other species of Euantha, we confirm that E. pulchra is a valid and distinct species.

ACKNOWLEDGMENTS

MDS is indebted to Nigel Wyatt (NHMUK) for facilities and kind assistance during his stay at the museum, and for kindly allowing to use the image capturing system of the NHMUK for taking photographs. We thank James O’Hara (Agriculture and Agri-Food Canada, Canadian National Collection of Insects, Ottawa, Canada) for the critical reading of the manuscript. Financial support from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES (MDS scholarship: 88882.333078/2019-01), Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq (MDS fellowship:150141/2022-0 and SSN research grant: 403165/2016-4, SSN fellowship: 309192/2018-8), and Fundação de Amparo à Pesquisa do Estado de São Paulo - FAPESP (SSN research grants: 2015/10788-0, 2016/50387-7).

REFERENCES

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Publication Dates

• Publication in this collection
  19 May 2023
• Date of issue
  2023

History

• Received
  29 Mar 2021
• Accepted
  31 May 2021