Hybobathus arx
Creators: name: Miranda, Gil Felipe Gonçalves
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Syrphidae
Hybobathus
Hybobathus arx

description: Hybobathus arx (Fluke, 1936)
Fig. 2
Baccha arx Fluke, 1936: 60. Type locality: Brazil, “Cois Parma Cos”. Holotype male (AMNH). Hull (1949): 97 (citation), 123 (key), 124 (key), 249 (Figs 259–261, abdomen), 274 (fig. 361, wing); Fluke (1956): 236 (catalog citation).
Ocyptamus arx. Thompson et al. (1976): 13 (catalog citation).
Hybobathus arx. Miranda (2017) (species list).
Baccha bivittata Curran, 1941: 276. Type locality: Brazil, Santa Catarina, Nova Teutônia. Holotype male (AMNH). Hull (1949): 97 (citation), 111 (key), 115 (key), 201 (fig. 48, abdomen), 278 (fig. 372, wing); Fluke (1956): 238 (catalog citation). syn. nov.
Ocyptamus bivittatus. Thompson et al. (1976): 13 (catalog citation).
Baccha titan Hull, 1947: 395. Type locality: Brazil, Santa Catarina, Nova Teutônia. Holotype male (AMNH) (synonym by Thompson et al. 1976).
Redescription. MALE (Figs 2a, d, e & g–i). Head (Figs 2d & e). Yellow; face with sparse white microtrichosity but concentrated laterally, with black pile, absent medially. Gena with white pile. Lunule with central black marking, black above central marking, and slightly expanding laterally, until the crease ventral to the frontal triangle. Frontal triangle with small triangular brown marking, and with black pile, getting shorter to absent medially. Base of antenna protuberant. Vertical triangle with shiny white microtrichia, except on ocellar triangle, which is dull black, with several irregular rows of black pile that concentrate into one row ending dorsal to the anterior ocellus; ocellar triangle separated by 1.4 times its length from the posterior margin of the head. Eye contiguity shorter than the vertical triangle length. Eye with weak sub-triangular indentation on posterior margin positioned around the level of antennal insertions. Antenna with black pile; postpedicel oval, with darkened dorsal 2/3. Occiput homogeneously covered by white microtrichia, with white pile, dorsal 1/3 with one row of flattened pile, ventral 2/3 with 2–3 rows, posterior row with longer and flattened pile, anterior rows of middle 1/3 with black pile. Thorax (Fig. 2a). Scutum black, but yellow laterally from postpronotum to scutellum; mostly covered by white microtrichia, denser medially, except for medial pair of short vittate and sub-lateral pair of long vittate areas without microtrichia; pile black and erect, with white pile laterally, with very short black pile on postalar callus, and with anterior continuous row of longer white pile. Scutellum yellow, with slightly darker medial region, with very short black pile, longer laterally; subscutellar fringe with long black pile. Pleuron yellow, dark on anterior 1/3 of posterior anepisternum, ventral 1/2 of katepisternum, meron and postero-ventral margin of katatergum; white pilose (proepimeron, anterior and posterior anepisternum, dorsal and ventral katepisternum, with pile patches separate, anterior anepimeron, katepimeron and metaepisternum), katatergum with long microtrichia giving it a ‘velvet’ appearance. Plumula white and of regular size. Calypter yellow, pile long and pale on margin of the ventral lobe and very short and dark on margin the dorsal lobe. Halter yellow, capitulum orange. Wing (Fig. 2a). Dark yellow, with large hyaline regions on apex of r1, middle and apex of r2+3, most of the middle of r4+5, middle of bm, middle of dm, middle of cup, middle of cua1, and wholly hyaline posterior margin; entirely microtrichose; alula hyaline, anterior margin brown, wide and convex, apically 3.8 times as broad as c cell, entirely microtrichose. Legs. Pro- and mesolegs yellow with yellow pile, longer on postero basal margin of the femora, and dark anteriorly on mesocoxa and on several rows of longer pile on postero-apical margin of the mesofemur. Metalegs yellow, except metafemur mostly brown, dark brown on a sub-apical small area, and with apex yellow, and metatibia dark brown except for base and apical 1/5, with mostly black pile but yellow on apex of metatibiae until the apex of the metatarsus; metabasitarsomere 2/5 of the length of the metatibia. Abdomen (Fig. 2a). Dark brown and petiolate, 2.5 times the length of the thorax. Tergite 1 yellow, except for dark brown apical margin, with long, black and erect pile, except for a few pale ones dorso-basally, and a bare area dorso-medially; sternite 1 yellow with long, yellow and erect pile. Tergite 2 rectangular and long, slightly compressed medially, 2.9 times longer than smallest width, pale on baso-lateral 2/3, with pair of fasciate yellow markings sub-apically; with long, black and erect pile; sternite 2 pale on basal 1/2 and brown on apical 1/2, with black appressed pile. Tergite 3 trapezoidal short, shorter than apical width and apical margin 1.75 times wider than basal margin, with a pair of central yellow vittae, slightly widening on the apex, which end on the apical 1/5, and a basal, sub-lateral pair of short vittate markings that join the central pair basally; pile black and appressed; sternite 3 mostly dark brown, except for yellow base, with black appressed pile. Tergite 4 rectangular, wider than long, central vittae narrow at apex and reaching the apical margin, remaining characteristics as on segment 3. Tergite 5 rectangular, short, wider than long, with four yellow narrow vittae; remaining characteristics as on segment 4. Genitalia (Figs 2g –i). Surstylus oval and elongated, in lateral and ventral views, with pile on dorso-basal 2/3, with ventral setulae on apical 1/3 and a few more on remaining ventrolateral margin; subepandrial sclerite quadrate, very slightly tapering towards apex, apical quadrate indentation 1/3 of the length of the sclerite, with a pair of shallow concave indentations baso-medially. Hypandrium rectangular, longer than wide in ventral view, ventral notch extending on apical 3/4, with concave basal margin, and with medial-lateral indentations extending dorsally; phallapodeme mostly unsclerotized; basiphallus drop-shaped but more elongated, in ventral view, apical 1/2 much higher than the tapering basal 1/2, anterior sclerotized surface of the distiphallus almost straight, tapering apically, base slightly extending laterally but not joining ventrally, with wider membranous area on apex, ventral surface completely membranous and with sparse microtrichia; postgonite large, with anterior margin mostly straight, with very short acute apico-dorsal extremity, and apico-ventral extremity as a long acute projection, with pile on basal 4/5 of the ventral margin.
FEMALE (Figs 2b, c, f & j–m). Like male except for the following characters: Frons with medial, wide, dark vitta that expands towards the lunule and connects to the dark color of lunule by a narrow medial vitta, with dark areas covered by white microtrichosity, differently oriented on ventral and dorsal 1/2. Ocellar triangle separated by twice its length from the posterior margin of the head. Vertex covered in white microtrichosity, differently oriented medially posterior to ocellar triangle, except absent on ocellar triangle, which is dull black. Overall pile of scutum black and shorter, and anterior row interrupted medially. Overall pile on scutellum shorter; subscutellar fringe inconspicuous. Dark areas of pleuron paler and more diffuse. Alula apically 4.5 times as broad as c cell. Abdomen twice longer than thorax. Tergite 1 with appressed pile; sternite 1 with shorter pile. Tergite 2 around 3.5 times longer than smallest width, and paler baso-laterally, with appressed pile. Central vittae of tergite 3 slightly curving towards sides, with additional medial, very narrow, inconspicuous pale vitta. Central vittae of tergite 4 end close to apical margin, are more distinct, and the sub-lateral markings are longer. Tergite 5 also with central vitta. Tergite 6 is 1/3 of the length of 5 and with vittae. Genitalia (Figs 2j–m). Tergite 7 as four sclerotized strips, the lateral ones narrower and joining basally to the medial triangular ones, pilose on apical 1/2; sternite 7 membranous, wholly pilose, with some longer pile on sub-apical row. Tergite 8 as a pair of lateral sclerotized strips that converge towards each other basally and run parallel to each other until the apex for the remainder of its length, with sparse pile and restricted laterally to sclerotized areas; sternite 8 with weak, long, narrow, lateral sclerotizations, wholly pilose. Epiproct as a pair of narrow, sclerotized, short strips, with very few pile apically, apodeme as long as the epiproct; hypoproct triangular and membranous, pilose. Cerci membranous, pilose, positioned apico-laterally and on a slightly perpendicular plane to the epiproct. With three round spermathecae with few protuberances on 1/2 of their surface.
Variation. MALE. Some specimens might present short vittate markings laterally to the facial tubercle; dark area of frons connects to dark of the lunule by wide vitta; frontal triangle marking may be larger and connect to the dark color of the lunule and the eye contiguity; vertical triangle might have sparse white microtrichosity medially and posterior to the ocellar triangle; ocellar triangle usually distanced its length from posterior margin of the eye. Katepisternum pile patches sometimes join anteriorly. Hyaline areas of the wing might be wider (light yellow on bc, c, sc, basal 2/3 of r1, and diffuse medially on r and posteriorly on bm). Pile might be black on the whole posterior margin of pro- and mesofemur; metabasitarsomere might be 1/2 the length of the metatibia. Apical margin of abdominal segment 3 might be twice wider than the basal margin. Hypandrium might have very few pile ventro-laterally (i.e. JSS32801). FEMALE. Vitta of the frons might not expand apically and not connect to the dark of the lunule; vitta of the frons might be widely connected to the dark of the lunule. Metaleg might be lighter. Central abdominal vitta might be only sub-shining; tergite 5 central vitta might be inconspicuous. Genitalia. Tergite 7 might have sparser pile.
Length. Body: male 14.5–17.6mm (n = 12), female 12.1–15.8mm (n = 9); wing: male 11.4–14.2mm, female 11.1–14mm.
Distribution. Brazil (Paraná, Rio de Janeiro, Rio Grande do Sul, Santa Catarina), Colombia (Quindio), Costa Rica (Puntarenas), Venezuela (Aragua).
Prey records. Montoya & Pérez (2009) recorded this species preying on Antianthe expansa (Germar, 1835) (Hemiptera, Membracidae).
Comments. Similar to H. persimilis (see comments under that species). The holotype of Baccha bivittata has a larger frontal triangle marking that connects to both the eye contiguity and the dark of the lunule. The facial dark markings mentioned by Curran are not very distinct on the holotype, but this weak state was also found in other specimens studied (e.g. JSS32801), which was dissected. With the exception of the ventral pile on the hypandrium and the weak facial markings, the specimen agrees with the remaining characters of the redescription of H. arx and is sympatric with other series of specimens of H. arx. Curran most likely did not think in comparing his Baccha bivittata to similar species, such as those of the H. arx group, since in his description he compares it with B. capitata [= Mimocalla capitata (Loew, 1863)], from which it is very different. Thus, due to the morphological evidences presented above, I place B. bivittata as a junior synonym of H. arx.
A female from Costa Rica (USNMENT01243073) has a wider vitta connecting the central marking of the frons to the dark of the lunule and overall lighter metaleg, but the genitalia agrees with other H. arx specimens. This disjunct distribution might indicate a different species, but the lack of more specimens (including a male) and distinct morphological characters hinders such an assumption.
Examined material. BRAZIL. Paraná, Ponta Grossa, Vila Velha-IAPAR, 22.iv.2002, leg. Ganho & Marinoni (DZUP048292) [1 ♀, DZUP]; Morretes, Sapintanduva Reserve, 28.v.1991, leg. A.L. Norbomm & C. Carvalho (USNMENT01243070) [1 ♂, USNM]. Rio de Janeiro, Floresta da Tijuca, 29.1.1968, leg. Moure & Seabra (DZUP 051562) [1 ♀, DZUP]; Petropólis (GFGM-MNRJ0016) [1 ♂, MNRJ]. Rio Grande do Sul, Pelotas, 13.v.1962, leg. C.M. Biezanko (USNMENT01243074) [1 ♂, USNM]. Santa Catarina, Nova Teutônia [Seara], xi– iv.1938 |1957|1959|1962|1966, leg. F. Plaumann (CNC_ Diptera 161374–6, JSS32800–1, JSS32403–4, JSS32797, JSS32979, JSS32983) [5 ♀ & 5 ♂, CNC, 1 ♂ holotype Baccha bivittata, AMNH]. [Unknown locality], Cois Parma Cos [1 ♂ holotype Baccha arx, AMNH]; EMBRAPA (GFGM-MNRJ0018) [1 ♂, MNRJ]. COLOMBIA. Quindio, Filandia, Granja Experimental Bengala, 13.xi.2009, leg. A.L. Montoya (CEUA47314) [1 ♂, CEUA, only studied from photographs]. COSTA RICA. Puntarenas, quary near Las Alturas Station, 12–17.viii.1995, leg. A.L. Norrbom [1 ♀, USNM]. VENEZUELA. Aragua, Rancho Grande, 18–27.ii.1971, leg. G. & M. Wood [1 ♀, CNC].
description: Published as part of Miranda, Gil Felipe Gonçalves, 2017, Revision of the Hybobathus arx and Pelecinobaccha summa species groups (Diptera: Syrphidae), pp. 1-43 in Zootaxa 4338 (1) on pages 5-8, DOI: 10.11646/zootaxa.4338.1.1, http://zenodo.org/record/1035669