Taxonomic revision of the Neotropical genus Argentinomyia Lynch-Arribálzaga, 1891 (Diptera: Syrphidae), with description of 16 new species Author Montoya, Augusto L. 0000-0003-3307-034X aleon.montoya@udea.edu.co Author Wolff, Marta 0000-0002-3389-7083 martha.wolff@udea.edu.co text Zootaxa 2023 2023-02-03 5234 1 1 157 http://dx.doi.org/10.11646/zootaxa.5234.1.1 journal article 53225 10.11646/zootaxa.5234.1.1 be77753c-0c7a-4f90-a020-f23b778d06d0 1175-5326 7609993 A540F250-BDE2-43F7-83A1-DA261F914B41 Identification key to the Neotropical genera of Melanostomini and Bacchini A key to the genera of Neotropical Melanostomini and Bacchini was prepared based on characters proposed by Fluke (1945 , 1957 ), Thompson (1999a) , Thompson (2006), Thompson et al. (2010) , Huo (2014) , Thompson & Skevington (2014) , Young et al. (2016) , Miranda & Moran (2017) , Ramage et al. (2018) and Mengual (2020) . 1. Postpronotum pilose (MCAD Fig. 30 ); male abdomen with four unmodified pregenital segments; 5 th tergum usually not visible in dorsal view (MCAD Figs 1 , 4 ); female abdomen tergum 6 th hardened or membranous, visible, if tergum 6 th and onward visible, then these are membranous; epiproct as two plates that may be connected to the base, or as a single plate, or as a band with two projections (subfamilies Eristalinae , Microdontinae and Pipizinae).... other flower flies (“MCAD key couplet 2”) - Postpronotum bare; male abdomen with five unmodified pregenital segments; 5 th tergum visible in dorsal view (MCAD Figs 53–61 ); female abdomen tergum 6 th hardened, visible; epiproct divided into two plates that may be connected to the base (subfamily Syrphinae )................................................................................. 2 2. Face and/or scutellum partially yellow or yellowish-brown in background color; phallus (aedeagus) two-segmented........................................................................................ other Syrphinae genera - Face and scutellum entirely black in background color (some species with partly pale face or scutellum); phallus (aedeagus) simple, unsegmented (Bacchini and Melanostomini )......................................................... 3 3. Face usually straight, oral margin and antennal bases in line, without tubercle, flat, straight or convex; abdomen petiolate, distinctly narrower than thorax ( Fig. 4A , MCAD Figs 59 , 60 ); male: 2 nd tergum narrow, narrower than 3 rd and 4th terga ( Mengual et al. 2018 , Fig. 18 ); female abdominal tergum 6 th , not noticeable nor visible without dissection, tergum 6 th internal to the 5 th , tergum 5 th 1/10 of the length of tergum 4 th , almost inconspicuous ( Miranda & Moran 2017 , Figs 59 , 80 and 90 )................................................................................................ Leucopodella Hull - Face with tubercle; abdomen parallel-sided or narrowly oval (MCAD Figs 55 , 58 ); other characters variable; female tergum seventh visible without dissection........................................................................ 4 4. Antennal cavities broadly confluent (MCAD Fig. 24 ); face narrow, with distinctive, rounded facial tubercle; metathoracic pleuron with several fine subappressed pile ventral to spiracle; katepisternum with pile patches broadly separated posteriorly, but joined anteriorly; abdomen oval, wide and flat, clearly broader than scutum, usually with yellow-orange maculae on 2 nd to 4 th terga; surstyli elongated, one-lobed, digitiform or pointed, generally widened apically, postgonites small, squarish or triangular in shape ( Fluke 1957: 278 , Figs 119–122; Borges & Pamplona 2003 ); female tergum 5 th 1/3 of the length of tergum 4 th , tergum 6 th 1/3 of the length of 5 th ( Miranda & Moran 2017 , Figs 66 , 84 and 97)................. Xanthandrus Verrall - Antennal cavities broadly separated (MCAD Fig. 23 ); metathoracic pleuron bare; katepisternum with pile patches usually broadly separated throughout; abdomen variable, slender and parallel-sided, as broad as scutum; other characters variable... ................................................................................................... 5 5. Metasternum greatly reduced to a small diamond-shaped area ( Figs 3A , 5J ; Andersson 1970: 273 , Fig. 1C , 3C ; Shatalkin 1975: 118 , Fig. 11 ; Thompson et al 2010: 771 , Fig. 34 ; Haarto and Ståhls 2014: 95 , Figs 1A ; Thompson & Skevington 2014 ); antenna short, with scape and basoflagellomere as long as wide; face not produced below, with small tubercle, facial pollinosity neither punctate nor rippled (MCAD Fig. 28 ); male abdomen nearly parallel-sided, from two to five times as long as greatest width, female with abdomen varying from nearly parallel-sided to oval, from 1.7 to 2.5 times as long as greatest width; usually with triangular or subquadrate shaped yellow maculae; male genitalia with surstyli simple, one-lobed, elongate, straight and thin, with a small basomedial tubercle; postgonites (apex of hypandrium) massive, irregular or squarish in shape; female tergum 5 th 1/4 of the length of tergum 4 th , tergum 6 th 1/5 of the length of tergum 5 th ......................... Melanostoma Schiner [Note: A new species described from Cameroon by Mengual (2020) does not have the reduced metasternum] - Metasternum entire, not reduced ( Fig. 3B ; MCAD Fig. 35 ; Haarto and Ståhls 2014: 95 , Fig. 1B ; SNLSA Fig. 12C ); face variable, almost straight in profile with weak tubercle or moderately to strongly produced forward ventrally, sometimes with pollinosity forming punctuate or rippled pattern, other characters variable........................................ 6 6. Face produced forward into a snout, with a very prominent and abrupt tubercle closer to the antennal base than to the oral opening apex ( Fig. 4N , Fluke 1943: 427 , Figs 1–7 ); face sparsely pollinose and without punctate shiny (bare) maculae ( Fig. 4N ); head as long as or longer than high, wider than thorax; male eyes dichoptic or holoptic; antenna elongate, as long as or longer than face; basoflagellomere elongate, four or more times as long as broad, near equal to scape and pedicel together ( Fig. 4N ); notopleura without a distinct tubercle; subscutellar fringe short, thin and white; prolegs simple in male, sometimes with a curled tibial seta ( Fig. 4N , Fluke 1943: 427 , Figs 8–9 ); male genitalia with surstyli curved; superior lobes transverse and elongated; ejaculatory apodeme elongate and knobbed toward the apex ( Fluke, 1957: 278 , Figs 124–125; Shatalkin 1975: 118 , Fig. 12 ); small species, shining black or blue metallic, 7mm or less.............. Platycheirus ( Tuberculanostoma ) Fluke - Face straight or slightly produced anteriorly, with a low and indistinct tubercle, frequently densely pollinose and with small shiny punctate-like bare maculae; head higher than long; male eyes face not greatly produced anteriorly; basoflagellomere oval or slightly elongate, never more than twice as long as broad; notopleura with a distinct tubercle; subscutellar fringe complete; male sometimes with legs modified, either broadened or with special bristles, pile tufts, modified hairs or none; frequently medium to large flies, sometimes with pale to metallic colored markings......................................... 7 7. Face slightly receding to rather strongly produced below, with obscure to prominent tubercle, densely pollinose and sometimes with pollinosity forming a distinctive bare punctum or rippled pattern ( Fig. 4M ); male protibia usually with long black bristles posteriorly, sometimes protibia and/or tarsus expanded, usually with specialized setae ( Fig. 4M ); abdomen nearly parallel-sided in males, narrowly oval in the female; with yellow to orange or silver-gray pollinose on bluish submetallic macula, generally with quadrate markings; surstyli bifid or bilobed with a long, slightly curved lateral lobe and a short, stout basomedial lobe, superior lobes usually slender, recurved and crescent-shaped ( Vockeroth 1990 : Fig. 83 ; Thompson & Skevington 2014 ; Young et al. 2016 ); female tergum 5 th 1/3 of the length of tergum 4 th , tergum 6 th 1/5 of the length of tergum 5 th ( Miranda & Moran 2017 , Figs 70 , 71 , 86 and 100).......................................................... Platycheirus ( Carposcalis ) - Face straight in profile, not produced anteriorly, usually uniformly pollinose, sometimes with shiny (bare) punctate maculae; male legs slender, without bristles, pile tufts, or modified hairs; abdomen frequently with pale-colored maculae; surstyli elongate, one-lobed, postgonites massive, irregular, elongate, triangular, or squarish in shape......................... 8 8. Antennae short, scape broader than long, scape nearly equal to pedicel, basoflagellomere large, slightly oval and apically rounded; face slightly receding to perpendicular with a well-rounded tubercle, never with transverse grooves dorsally along tubercle neither broadly (bare) punctuate ( Fig. 6D ); mesocoxa pilose posteriorly ( Fig. 6E , SNLSA Figs 12–13 ); abdomen elongated or with parallel sides, with four to five pairs of large rounded to triangular markings on terga, always with small macula on 5 th tergum; male genitalia greatly enlarged and strongly sclerotized, apex of hypandrium (superior lobes) and cerci elongated, surstyli three to four times longer than wide ( Fig. 6G , Fluke 1957: 278 , Fig. 123; SNLSA Figs 14A–D ); female tergum 5 th 1/4 of the length of tergum 4 th , tergum 6 th 1/5 of the length of tergum 5 th (SNLSA Figs 13E )...... Talahua Fluke [Note: Montoya & Wolff (2020) provided a complete redescription for Talahua , differential diagnosis, images of the habitus and illustrations of male genitalia] - Antenna elongate, scape longer than broad; basoflagellomere oval or elongate; face straight in profile ( Figs 4 , 6 – 9 , MCAD Fig. 22 ), facial tubercle low dorsally, not distinct ( Figs 4 , 6 – 9 ); mesocoxa bare posteriorly; male genitalia normal size, apex of hypandrium (superior lobes) triangular to rectangular, irregular in shape and cercus short; female tergum 5 th 1/3 of the length of tergum 4 th , tergum 6 th 1/4 of the length of tergum 5 th ( Figs 5 , 6 and 9 )................. Argentinomyia Lynch-Arribálzaga