Melanostomini (Mengual, 2020)

Montoya, Augusto L. & Wolff, Marta, 2023, Taxonomic revision of the Neotropical genus Argentinomyia Lynch-Arribálzaga, 1891 (Diptera: Syrphidae), with description of 16 new species, Zootaxa 5234 (1), pp. 1-157 : 12-13

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

Figures

FIGURE 1. A. Illustration of the dorsal habitus of Argentinomyia testaceipes in the original description of Lynch Arribálzaga (1891: 269, Plate, Fig 4); B. Dorsal habitus of a female specimen photographed by X. Mengual; available online at: http:// syrphidae.myspecies.info/taxonomy/term/117.

FIGURE 3. Detail of metasternum development: A. Metasternum highly reduced in Melanostoma; B. Metasternum entire, not reduced in Argentinomyia. Abbreviations: Mtst: Metasternum; Cx 3: Coxae 3.

FIGURE 4. Differences in head morphology, colouration and pollinosity patterns, frontal view: A. Leucopodella sp. (♁); B. Argentinomyia longicornis (♀);C. Argentinomyia rugosonasa (♀);D. Argentinomyia jamaicensissp. nov. (♀);E. Argentinomyia testaceipes (♀); F. Argentinomyia tropica (♀); G. Argentinomyia nigrans (♀); H. Argentinomyia browni (♀); I. Argentinomyia crenulata (♀); J–K. Argentinomyia norrbomi sp. nov. (♁): J. lateral view, K. frontal view; L. Argentinomyia longicornis (♁), lateral view; M. Platycheirus (Carposcalis) (♁), frontal view; N. Platycheirus (Tuberculanostoma) (♁), lateral view. Scale bar: 5 mm.

FIGURE 5. Female postabdomen. A. Lateral view of Argentinomyia norrbomi sp. nov.; B. Posterior view of the abdominal apex of Argentinomyia occidentalis sp. nov.; C. Dorsal view of distended abdomen of Argentinomyia luculenta. Abbreviations: Ap: apodeme of epiproct; Cer = Cercus; Ep: Epiproct; Hp: Hypoproct; Scl: sclerotized area; Sper: Spermatheca; Tg: tergite. Scale bars: 0.05 mm.

FIGURE 6. Differences in antennae morphology, dorsal view: A. Argentinomyia luculenta (♀); B. Argentinomyia testaceipes (♀); C. Argentinomyia catabomba (♀); D–G. Talahua fervida (♁): D. Head, frontal view, E. Metacoxa pile tuft, ventral view, F. Scutellum emarginated, dorsal view, G. Genitalia, lateral view; H. Argentinomyia CR-18 (♁); I. Argentinomyia sagoti sp. nov. (♀); J. Metasternum of Melanostoma sp.; K. Scutellar pile of Argentinomyia rex; L. Antennal cavities broadly confluent of Xanthandrus sp. Scale bar: 1 mm.

FIGURE 8. Differences in wing macula pattern, lateral view. A. Argentinomyia crenulata (♀); B. Argentinomyia sagoti sp. nov. (♁); C. Argentinomyia CR-18 (♁).

FIGURE 9. Pattern of abdominal terga, dorsal view: A. Talahua fervida (♀); B. Argentinomyia norrbomi sp. nov. (♀); C. Triangular maculae in Argentinomyia nigrans (♀); D. Argentinomyia rugosonasa (♁); E. Argentinomyia belmira sp. nov. (♀); F. Lineal maculae in Argentinomyia lineata (♁); G. Oblique maculae in Argentinomyia longicornis (♀); H. Argentinomyia andina (♁), head frontal view; I. Argentinomyia currani (♁), abdomen lateral view. Scale bar: 1 mm.

FIGURE 11. Argentinomyia agonis (Walker, 1849), male genitalia. A. Whole genitalia including epandrium, cercus and surstylus, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view.Abbreviations used in male genitalia structures are as follows: Ahp = apex of hypandrium (superior lobes); Cer = Cercus; Epd = Epandrium; Hyp = Hypandrium; Led = Aedeagal lobe; Sur = Surstyle. Scale bar: 0.05 mm. D–E. Natural habitus of male and female specimens in Puerto Villamil, Galapagos, Ecuador (iNaturalist catalogue number37254474; https://www.inaturalist.org/observations/37254474). Photo taken by ©Robert Siegel.

FIGURE 12. Argentinomyia altissima (Fluke, 1945), male (CEUA 93080): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (CEUA 43354): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 13. Argentinomyia altissima (Fluke, 1945), male genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm. D–E. Natural habitus of a female specimen in Pumapaccha, Cuzco, Perú (iNaturalist catalogue number# 37168068; https://www.inaturalist.org/observations/37168068). Photo taken by ©Jared Shorma.

FIGURE 14. Argentinomyia aurifacies sp. nov., male Holotype (USNM ENT 01443646): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (USNM ENT 00038431): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 18. Argentinomyia berthae (Lima, 1946), male Neotype (INPA–DIP 000095): A. Head, frontal view B. Dorsal view; C. Head, lateral view. Photo taken by ©Gil Felipe Miranda in Miranda (2017). Female (USNM ENT 01443843): D. Head, frontal view; E. Dorsal view; F. Lateral view; G. Posterodorsal view (USNM ENT01443843). Scale bars: each bar is equal to 1 mm.

FIGURE 22. Argentinomyia browni (Fluke, 1945), male (USNM ENT 00058849): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (USNM ENT 01443719): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 23. Argentinomyia browni (Fluke, 1945), male genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm.

FIGURE 24. Argentinomyia catabomba (Williston, 1891), male (ECO–TAP–E 483): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (ECO–TAP–E 1715): D. Head, frontal view; E. Dorsal view; F. Lateral view (CNC DIPTERA 112220). Scale bars: 5 mm.

FIGURE 28. Argentinomyia currani (Fluke, 1937), male (USNM ENT 01406227): A. Head, frontal view; B. Detail of triangular maculae, dorsal view; C. Lateral view (Detail of black ring or smudge on the apical margin of metafemur). Female (USNM ENT 01406289): D. Head, frontal view; E. Detail of triangular maculae, dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 30. Argentinomyia fastigata (Fluke, 1945), male (USNM ENT 01406314): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (USNM ENT 01406314): D. Head, frontal view; E. Dorsal view (CEUA 103448); F. Lateral view (USNM ENT 01406314). Scale bars: 5 mm.

FIGURE 34. Argentinomyia humboldti sp. nov., female Holotype (CEUA 98063): A. Head, frontal view; B. Dorsal view; C. Lateral view. Scale bars: 5 mm.

FIGURE 35. Argentinomyia ivani sp. nov., male Holotype (CEUA 95457): A. Head, frontal view; B. Dorsal view; C. Lateral view; D. Posterior view, detail of maculae on 3rd and 4th terga. Scale bars: 5 mm.

FIGURE 53. Argentinomyia nigrans (Fluke, 1945), male (USNM ENT 01384670): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (USNM ENT 01406441): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 54. Argentinomyia nigrans (Fluke, 1945), male genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm. D–G. Rhysops funerea (Hull, 1949), male Holotype (CNC DIPTERA 169358). D. Latero–frontal view; E. Dorsal view; F. Lateral view; G. Label.

FIGURE 55. Argentinomyia norrbomi sp. nov., male Holotype (USNM ENT 01443832): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (USNM ENT 01443831): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 56. Argentinomyia norrbomi sp. nov., male Holotype, genitalia A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm.

FIGURE 57. Argentinomyia occidentalis sp. nov., male Holotype (CEUA 47448): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (CEUA 47447): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 58. Argentinomyia occidentalis sp. nov., male genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view; D. Male genitalia, lateral view; E. Female abdomen, posterior view, detail of maculae on 4th and 5th tergum. Scale bars: 1,5 mm. F–G. Type localities. F. Páramo Santa Rica in Andes Antioquia, Colombia. Photo taken by ©Augusto L. Montoya; G. Páramo del Sol in Urrao Antioquia, Colombia. Photo taken by ©Esteban Domínguez.

FIGURE 59. Argentinomyia opaca (Fluke, 1945), male (USNM ENT 00035708): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (USNM ENT 00035708): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 60. Argentinomyia opaca (Fluke, 1945), male genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm. D–E. Natural habitus of a female specimen at the Páramo ecosystem Santa Inés Belmira in Antioquia, Colombia: D. Dorsal view; E. Lateral view.

FIGURE 61. Argentinomyia plaumanni sp. nov., male Holotype (USNM ENT 00036936): A. Head, frontal view; B. Dorsal view; C. Lateral view. Scale bars: 5 mm.

FIGURE 66. Argentinomyia praeusta (Loew, 1866), male genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm.

FIGURE 70. Argentinomyia rugosonasa (Williston, 1891), male genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm. D. Natural habitus of a male specimen in El Calvario, Toluca, México (iNaturalist catalogue number 17119892; https://www.inaturalist.org/observations/17119892); E. Natural habitus of a female specimen in Toluca de Lerdo, México (iNaturalist catalogue number 8506135; https://www.inaturalist.org/ observations/8506135). Photos taken by ©Juan Carlos García Morales.

FIGURE 71. Argentinomyia sagoti sp. nov., male Holotype (ECOSCE): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (ECOSCE 24470): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 80. Argentinomyia teresae sp. nov., male Holotype, genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm.

FIGURE 83. Argentinomyia transversalis sp. nov., female. A. Head, frontal view; B. Dorsal view (USNMENT 00055996). C. Posterior view, detail of maculae pattern on abdomen; D. Lateral view (CEUA 87110). Scale bars: 5 mm.

FIGURE 84. Argentinomyia tropandeana sp. nov., male Holotype (CEUA 13210): A. Cabeza, Vista frontal; B. Dorsal view; C. Lateral view. Female (QCAZ 103714): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 86. Argentinomyia tropica (Curran, 1937), male (CEUA 93084): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (CEUA 69474): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 90. Geographical distribution of Argentinomyia species in the Tropical Andes.