Argentinomyia agonis ( Walker, 1849 )

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 : 25-28

Argentinomyia agonis ( Walker, 1849)

Proposed standard English name: Darwin’s long-antennae flower fly.

( Figs 10 , 11 and 95 )

Syrphus agonis Walker, 1849: 588 . Type locality: Ecuador: Galápagos Islands. LECTOTYPE Male BMNH I 914459 designated by Sinclair et al. (2016: 88) (Examined). Refs.: Williston, 1887: 28; Kertész, 1910: 101; Sinclair & Peck 2002; Boada 2005; Sinclair et al. 2016: 88 (Lectotype designation; Figs 13–15 ); Sinclair 2017

Syrphus agonis . van der Goot, 1964: 215

Rhysops agonis . Linsley, 1977: 39 (records)

Rhysops agonis . Thompson et al. 1976: 42

Argentinomyia agonis . Thompson, 2006: 9

Argentinomyia agonis . Sinclair et al. 2017

Argentinomyia agonis . Marín-Armijos et al. 2017: 168

Type material. LECTOTYPE. Adult Male, ECUADOR. Islas Galapagos, Collected by Charles Darwin, Esq. LECTOTYPE Male BMI(E) 914459. Lectotype designated by Sinclair 2017; Sinclair et al. (2016: 88)

Length (n= 3): Body, 7.1–8.4 mm; Wings, 6.2–6.4 mm.

Diagnosis. Antenna black; wing hyaline, vein R4+5 not sinuate; cell r1 open; vein M1 not recurrent; metafemur and protibia black, only yellow on apical 1/5 and basal 1/3, respectively; abdomen elongate, 2 nd to 4 th terga with large orange maculae, black lateral margins, in addition to a thin median black vitta and narrow posterior black margin; surstylus with dorsal and ventral margins approximately of the same width in the whole length, elongated, three to four times longer than broad; hypandrium narrowed laterally towards the apex; aedeagal lobe circular, apex rounded.

Redescription. MALE. Head ( Figs 10A ): Face black, white pollinose, white pilose; tubercle low, bare, area above the tubercle brown pollinose. Frontal triangle white to brownish-grey pollinose laterally, black pilose. Gena ferruginous; occiput black pilose dorsally, yellow hoary ventrally. Antenna dark brown, short, ratio 1.0:1.3:2.4, basoflagellomere as long as the scape and pedicel together, pile black, apically rounded; arista brown, bare. Thorax ( Figs 10B–C ): Yellowish gray pollinose, pleura with short yellow pile; mesonotum black, golden pollinose, with short yellow pile, with some black pile in the apical area before the scutellum; scutellum black, disc with a transversal stripe, yellow and black pile intermixed, marginal pile long and yellow. Wing ( Fig. 10C ): Slightly yellowish to subcinereus, stigma yellow-brownish, microtrichose, vein R4+5 not sinuate; cell r1 open; vein M1 not recurrent; calypter wholly yellowish-white; plumula white; halter white, capitulum white. Legs ( Fig. 10C ): Black yellow pilose, pro-, meso- and metafemur black, only yellow on apical 1/5, without basoventral setal patch; pro-, meso- and metatibia yellow on basal 1/3 or more, pile inconspicuous, black; coxae golden pilose, tarsus black. Abdomen ( Fig. 10B ): Elongate, mostly yellow, 2 nd to 4 th terga with large orange maculae, with black lateral margins, in addition to a thin median black vitta and narrow posterior black margin; 5 th tergum almost entirely yellow with only a small posteromedian black triangle, genitalia shining black, black pilose; male genitalia: surstylus in lateral view ( Fig. 11A ) with dorsal and ventral margins approximately of the same width in the whole length, elongated, three to four times longer than broad; hypandrium in ventral view ( Fig. 11C ) narrowed laterally towards the apex; aedeagal lobe in ventral view ( Fig. 11C ) circular, apex rounded.

FEMALE ( Figs 10D–F , 11D ). Similar to male except for: usual sexual dimorphism and differing in the size of the abdominal maculae, which are comparatively wider in the female; face grayish-brown pollinose, running throughout the middle area of the frontal triangle. Female of the Galápagos endemic A. agonis is similar to high Andean species A. belmira sp. nov., from which it differs in having the 2 nd tergum is almost entirely yellow, with a pair of wider yellow maculae from the base to the apical margin of the segment, with a thin median black stripe and narrow posterior black margin; face orange pollinose at the frontal triangle.

Taxonomic notes. Argentinomyia agonis is a black fly similar in appearance and abdominal maculae pattern to A. belmira sp. nov. but can be readily differentiated by the following combination of characters: Antenna black ( Fig. 10A, C , D-F); wing hyaline, vein R4+5 not sinuate; cell r1 open; vein M1 not recurrent ( Fig. 10 B-C, E-F); metafemur and protibia black, only yellow on apical 1/5 and basal 1/3, respectively ( Fig. 10A, C , D-F); abdomen elongate, 2 nd to 4 th terga with large orange maculae, black lateral margins, in addition to a thin median black vitta and narrow posterior black margin ( Figs 10B, E , 11 D-E). Argentinomyia belmira sp. nov. is characterized by a dark reddish-brown antenna ( Fig. 16A, C , D-F); wing slightly brownish ( Fig. 16 B-C, E-F); legs brown to black, black pilose, 1 st and 2 nd metatarsus orange-yellow, others black ( Fig. 16A, C , D-F); 3 rd and 4 th terga almost entirely yellow, with a pair of wider yellow maculae from the base to the apical margin of the segment, rounded in the lateral edge and with a thin median black stripe and narrow posterior black margin; 5 th tergum almost entirely yellow with only a small posteromedian black triangle ( Figs 16B, E ). Based on males, A. agonis differs from A. belmira sp. nov. in having the surstylus in lateral view ( Fig. 11A ) with dorsal and ventral margins approximately of the same width in the whole length, elongated, three to four times longer than broad [versus surstylus with dorsal margin slightly concave and ventral margin slightly convex, shorter than broad in A. belmira sp. nov. ( Fig. 17A )] (see “diagnosis” under each species or key).

Remarks. According to Sinclair et al. (2016: 86), A. agonis run out to Platycheirus pictipes ( Bigot, 1884) in the last revision of the Neotropical Melanostomini ( Fluke 1945) . However, A. agonis differs considerably from the Bigot species by its unique abdominal pattern. Argentinomyia agonis has been associated with the pollination of Miconia robinsoniana (Melastomataceae) in Santa Cruz Island (Media Luna) a species that is considered as Endangered in this Archipelago ( Boada 2005; Sinclair & Peck 2002, 2005; Sinclair et al. 2016; Sinclair 2017). This species was previously only known from two male specimens. Here, we expand the number of known males collected, associated with the female described for the first time.

Comments. The Holotype specimen of Syrphus agonis is currently in the BMNH. Photos are available on their website BMNH: https://data.nhm.ac.uk/uk_UA/dataset/56e711e6-c847-4f99-915a-6894bb5c5dea/resource/ 05ff2255-c38a-40c9-b657-4ccb55ab2feb?q= Argentinomyia &view_id=6ba121d1-da26-4ee1-81fa-7da11e68f 68e&filters=typeStatus%3Aholotype%7Cfamily%3Asyrphidae%7Cgenus%3A Argentinomyia &field=associ atedMediaCount&value=.

Distribution. Argentinomyia agonis (n= 8) is distributed in the Galápagos Island in Ecuador (Islands Floreana, Isabela, San Cristobal, Santa Cruz and Pinta) ( Fig. 95 ). The species is endemic to the Northern Andes domain at low elevations (234–550 m) in the Galápagos Islands province.

Non-type material examined. ECUADOR. Galapagos, Isla Floreana, -1,31347, -90,440123, 334m; Isla Isabela, -0,778118, -91,041158, 366m; Isla Isabela, Serra Negra, -0,83, -91,17, 1000 m, Sweeping pamp, 3- 11.ii.1989, B.J. Sinclair (1♁, CNC DIPTERA 246832); Isla San Cristóbal, -0,853699, -89,433112, 234 m; Isla Santa Cruz, -0,658918, -90,354343, 550m; Isla Pinta, 0,582 785, -90,756875, 584m ( Sinclair & Peck 2002; Sinclair et al. 2016; Sinclair 2017); Isla Pinta, Transition Zone Forest, 0,591 95, -90,762788, 200 m, forest Malaise trap ( Bursera sp. , Trema sp. and Zanthox sp.) 14-22.iii.1992, S. Peck and B.J. Sinclair, 92-38 (1♀, CNC DIPTERA 246840); Puerto Villamil, -0,954444, -90.964134, 8 m, Robert Siegel (iNaturalist catalogue number# 37254474; https://www. inaturalist.org/observations/37254474).

Figures

FIGURE 10. Argentinomyia agonis (Walker, 1849), male (CNC DIPTERA 24684): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (CNC DIPTERA 246840): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 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 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 15. Argentinomyia aurifacies sp. nov., male Holotype, genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm.

FIGURE 16. Argentinomyia belmira sp. nov., male Holotype (CEUA 95284): A. Head, frontal view; B. Dorsal view; C. Lateral view. Female (CEUA 95481): D. Head, frontal view; E. Dorsal view; F. Lateral view. Scale bars: 5 mm.

FIGURE 17. Argentinomyia belmira sp. nov., male Holotype, genitalia A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 mm. D. Type locality in a pristine Andean forest at the Páramo of Santa Inés Belmira in Antioquia, Colombia. The specimens were collected flying in leks over the Native Bromeliad species, Guzmania coriostachya (Bromeliaceae).

FIGURE 95. Geographical distribution of Argentinomyia species in the West Indies and the Galápagos Islands.