Masarygus planifrons Brèthes, 1908:442

The genus Masarygus has only one species, M. planifrons, and it has postmetacoxal bridge complete; abdomen not petiolate; vein R4+5 without an appendix; vein M without appendix and vein M1 never processive; mouthparts absent; scape very short, only as long as broad; antenna inserted dorsally on head, at or above dorsal margin of eye; male basoflagellomere with multiple furcations.

Hull (1949) mentioned some diagnostic characters; one of the most important is the male basoflagellomere divided into four branches (simple in females) and metafemur and metatibia greatly thickened and with bristle-like setae.

From original description (Brèthes, 1909) in latin.

FEMALE.

Omnino breve (haud dense) obscure pilosulo. Caput flavum, margine oculorum interiore verticeque nigris vol piceis, antennis articulis 2 primis obscure ferrugineis, articulo 3° piceo, seta hujus articuli dimidium longitudinis aequante, flavo-ferruginea. Thorax niger, mesonoto utrinque posticeque et propleuris albidis. Halteres albidae. Abdomen segmentis 1° obscure testaceo, 2° apice anguste albido, 3° apice utrinque maculis 2 sat magnis albidis, 4° utrinque maculis 2 longioribus, ventre arcubus transverse rugulosis et piceis. Pedes picei, tibiis 4 anticis et tarsis omnibus (protarso postico obscure) ferrugineis, unguibus nigris, pulvillis albidis.

MALE differs from female: Sat albido-pilosulo, antennis articulo 3° 4-flabellato: laminibus exterioribas conjunctim furcatis, laminibus interioribus una a basi, altera a lamina superiore prope basin exsurgentibus; abdomine albo-testaceo, apicem versus gradatim lutescente, segmento 1° dimidio apicali nitido-piceo, segmento 2° in medio longitudinaliter tantum piceo, segmento 3° utrinque macula subbasali et in medio longitudinaliter paulum magis piceo, segmento 4° piceo utrinque maculis lutescentibus, segmentis ceteris et armatura piceis.

New description:

MALE.

Head: Face very broad, broader than eyes in frontal view, flat, straight; mouthparts absent, without tubercle, yellow, pale pilose; broadly dichoptic, eye with acute dorsal and ventral apex, narrow, bare; lunule dark; vertex separated from frons by sulcus and elevated, orangish- brown; vertical triangle brown; antenna very large, scape and pedicel orangish and as long as wide, basoflagellomere brown, greatly enlarged and divided into four branches; arista absent; occiput yellow, narrow ventrally and much broader dorsally.

Thorax: Scutum brown, yellow anteriorly, posteriorly and laterally, with short, pale pile; postpronotum yellow, yellow pilose; notopleuron mostly yellow, yellow pilose; scutellum small, brownish, dark pilose; subscutellar fringe absent. Pleuron mostly yellow, except anterior anepisternum and anteroventral half of posterior anepisternum brown, meron and katepisternum brown, and anterior anepimeron brown; metasternum appearing bare; postmetacoxal bridge complete; plumula absent; calypter yellow. Wing: Wing mostly destroyed in the syntype. Legs: Entirely brown, metafemur and metatibia slightly broad, metabasotarsomere very broad.

Abdomen: Parallel-sided, flat. Dorsum mainly yellow, except tergum 1 with brown fascia on posterior margin; terga 2 and 3 with medial narrow brown vitta and two medial brown maculae on lateral margins; tergum 4 with basal broad brown fascia on anterior margin and medial broad brown vitta joined forming a T-shaped marking. Terga 2 and 3 have a central broad depression that looks like “translucens”. Sterna poorly chitinized, appearing membranous.

FEMALE.

Similar to male excepts basoflagellomere simple, not multifurcate; arista subbasal, thick; face with two submedial depressions (probably to allocate the antennae); metabasotarsomere longer and thinner; abdomen slightly oval, mainly brown with tergum 1 yellow on basolateral corners, tergum 2 with medial yellow fascia on posterior margin; and terga 3 and 4 brown with two apicolateral large yellow macula creating a brown T-shaped marking.

Masarygus planifrons Bréthes, 1909.

Bréthes, J. 1909. Masarygidae, una nueva familia de dípteros. Anales del Museo Nacional de Buenos Aires ser. 3, tomo 10, 439-443.

Bréthes (1909) erecteda new family, Masarygidae, based on his new species Masarygus planifrons, and placed it between Conopidae and Scenopinidae. Bezzi (1910) placed Masarygus in the subfamily Microdontinae. Hull (1949) suggested Schizoceratomyia and Johnsoniodon as synonym of Masarygus. Papavero (1962) and Thompson et al. (1976) followed him. Thompson (2010) recognizes the genera Masarygus and Schizoceratomyia as valid.

The genus Masarygus has only one species, M. planifrons. Masarygus carrerai Papavero, 1962: 324 is placed under the genus Schizoceratomyia (Thompson 2010).

Body length: 6.5 mm (male); 5.6 mm (female).

Male and female syntypes collected in Buenos Aires, Argentina.