Argentinomyia scitula ( Williston, 1888 )

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 : 121-122

Argentinomyia scitula ( Williston, 1888)

( Fig. 73 )

Melanostoma scitulum Williston, 1888: 264 . Type locality: BRAZIL. Mato Grosso, Chapada. SYNTYPE 2 Male AMNH (Examined). Refs.: Fluke, 1945: 7 (redesc.) 29 ( Fig. 43 , male abdomen, Fig. 54 , wing)

Rhysops scitulum . Williston, 1907: 2

Rhysops scitula . Curran, 1937: 2 (key)

Rhysops scitula . Fluke, 1945: 7

Rhysops scitulus . Thompson et al. 1976: 44

Type material. HOLOTYPE. Adult male, BRAZIL. Mato Grosso, Chapada , 15°27’43.51”S, 55°44’54.20”O, 716 m ( AMNH).

Length. Body, 7.2–8.0mm; Wings, 5.7–6.4mm.

Diagnosis. Argentinomyia scitula is similar to Argentinomyia longicornis differing by the following combination characters: Basoflagellomere as long as the scape and pedicel together; wings with two short, transverse maculae in front on median half, microtrichose; protarsus are wholly yellow; abdomen with a basal pair of elongate yellow maculae on 3 rd tergum reaching the apical 1/3, a similar smaller pair on 4 th tergum separated from the base of tergum and occupying 1/2 its length.

Redescription. MALE. Head (Adapted from Williston 1888 and Fluke 1945). Sides of the face with a slender vitta and spot of pollen, not punctulate. Antennae brownish, orange ventrally, less elongated, the three segments of nearly equal length, basoflagellomere not twice as long as wide. Thorax: Black, mesonotum shining, with two faint whitish-pollinose vittae on anterior half, yellow pilose, the side brownish pollinose, pile brownish. Pleura shining black with a light coating of white to brownish pollen, mesopleura with brownish metallic reflections, yellow pilose. Scutellum shining, slightly rugose on apical 1/2, pile long and yellow, fringe long and yellow. Wing ( Fig. 73 ): Hyaline, stigma light brownish, elongate, anterior cross-vein (r-m) clouding; calypter wholly dark brown; plumula light brown; halter yellowish-red, capitulum slightly brownish. Legs: Yellow, pro- and mesotibiae yellow; pro- and mesofemora dark brown, yellow at the anterior 1/4, femur narrowly yellow at the base; pro- and metafemora only pale brown on basal 1/2 but may be quite dark on fully matured specimens. Abdomen ( Fig. 73 ): narrow, of nearly equal width throughout; with a basal pair of elongate yellow maculae on 3 rd tergum reaching the apical 1/3, a similar smaller pair on 4 th tergum separated from the base of tergum and occupying 1/2 its length.

Remarks. Fluke (1945) was unable to recognize A. scitula (Williston) among the numerous specimens he studied from southern Brazil. Fluke reviewed a male from the AMNH ( Fig. 73 ) pointing out that the opacity of the anterior transverse vein (r-m) is quite characteristic, but it is not entirely reliable as other species such as A. crenulata also have a slightly brown macula along this vein. These characteristics were verified and corroborated during the visit to the AMNH.

The Holotype in the AMNH is a specimen collected in Chapada , Rio Grande do Sul, Brazil. Apparently, A. scitula could be a valid species, but as the Holotype is a headless, teneral and undissected male, there were nonadditional specimens found, although extensive material from Brazil was examined, therefore, the identity of the species remains doubtful and a more in-depth morphological analysis will be necessary to clear up its validity .

Comments. The Holotype specimen of M. scitulum is currently in the AMNH. Photos are available on their website AMNH: https://sci-web-001.amnh.org/imulive/iz.html?#details=ecatalogue.10020982.

Geographical range. Argentinomyia scitula is distributed in Brazil (Rio Grande do Sul).

Figures

FIGURE 43. Argentinomyia lineata (Fluke, 1937), male genitalia. A. Whole genitalia, lateral view; B. Epandrium, dorsal view; C. Hypandrium, ventral view. Scale bars: 1 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 73. Argentinomyia scitula (Williston, 1888), male Holotype, AMNH (Headless).