Tethysimyia chilensis, Ebejer, 2023

Ebejer, Martin J., 2023, A first account of Chyromyidae (Diptera: Acalyptratae) from continental Central and South America and some Caribbean Islands, with descriptions of new species, Zootaxa 5319 (3), pp. 301-331 : 318-321

Tethysimyia chilensis sp. nov.

Figs 11–12

Material: holotype ♁, CHILE: Antofagasta, 6 km SW of Calama, 0.53 km ENE of Las Cascadas of Rio Loa, 05.ii.2018, leg. M. von Tschirnhaus, sweeping dense vegetation ca. 2168m a.s.l., semidesert biotope, (MNNC-8391), critical point dried; 4♁♁, 9♀♀, same data as holotype, ( SDEI-C 1 2209), critical point dried; 3♁♁, 5♀♀, same data as holotype, ( MJE), critical point dried; 2♁♁, 2♀♀, same data, ( SDEI-C 1 2209), preserved in alcohol; 2♁♁, 6♀♀, Antofagasta, Rió Loa, gorge 3 km N Chíuchíu, 33 km ENE Calama, 22°18ʹ53.2"S 68°38ʹ53.0"W, 2602 m asl, 09.ii.2018, leg. M. von Tschirnhaus, sweeping Daucus carota , Beta vulgaris & Apiaceae , (SDEI-Cl 2210), preserved in alcohol; 3♁♁, 3♀♀, Región de Antofagasta, swamp, Rió Salado, 2539 m asl, 22°20’23.8"S 68°35ʹ59.5"W, 09.ii.2018, leg. M. von Tschirnhaus, sweeping Juncus , Asteraceae , Poaceae alongside the water, round Laguna Chiu Chiu, (SDEI-Cl 2211), critical point dried; 3♁♁, 4♀♀, same data, (MNNC-8392–8398), critical point dried; 1♁, 1♀, same data, ( MJE), air dried; 1♁, 7♀♀, Tarapaca, beach “Caleta de Camarones”, Río Camarones, 133 km S. Iquique, 21°25ʹ48.5"S 70°03ʹ26.0"W, 5 m asl, sweeping Bolboschoenus and a salt grass near stream, 22.ii.2018, leg. M. von Tschirnhaus, (SDEI-Cl 2228), preserved in alcohol.

Diagnosis: A pale yellow species except for light brownish mediotergite; eye elongate oval; male with long brown setae on epandrium.

Description

Male.

Head: all yellow except for brown ringed ocelli; almost twice as broad as long; frons at vertex, viewed dorsally about as wide as eye; narrowed anteriorly, at level of antennae about 0.6 width that at level of anterior ocellus; eye lying oblique, long oval about twice as long as high; gena narrow in front, deeper behind, in profile, below middle of eye, about 0.8 height of short diameter of eye, with numerous short, yellowish white setulae; occiput in profile flat, slightly concave above, barely visible behind posterior pole of eye, with postocular setulae in one row; mouth parts all yellow; 2 vibrissal setulae moderately developed: longest about equal to anterior fronto-orbital seta; face short, poorly sclerotized and depressed; median carina barely discernible; antenna yellow, pedicel with distinct short seta dorsally; basal flagellomere small and round; first segment of arista yellow, second yellow basally and brown over greater part distally, bare; chaetotaxy: 2 reclinate fronto-orbitals with 2–3 short lateroclinate setulae in front, paraverticals absent; 1 inner and 1 outer vertical, both strong; ocellars, proclinate and diverging, a pair of short setulae between posterior ocelli; about 24 short setulae across middle of frons.

Thorax: yellow; scutum and scutellum slightly deeper yellow than pleura; mediotergite brownish yellow; chaetotaxy: proepisternal setula absent, 1 postpronotal, 1 posthumeral, 2 notopleurals, 1 postalar, 0+2 dorsocentrals, anterior of which, short, about half length of posterior; acrostichals short in 6 irregular rows with prescutellars only a little longer, 4 scutellars, 1 anepisternal, 1 katepisternal at upper posterior corner and 1 long, seta at ventral corner directed downwards, 1 intrapostalar; postsutural prealar absent.

Wing: veins all pale yellow; distance on costa between R 2+3 and R 4+5 about 0.6 that between R 4+5 and M; distance between cross veins about 1.4 length of posterior cross vein, which is about 0.3 length of apical section of vein Cu. Haltere pale yellow.

Legs: not modified except for slightly thicker femora; numerous pale setulae scattered on all pairs of legs, in addition longer setulae present on fore femur; mid tibia with apico-ventral seta; claws black in apical half and pulvilli normal.

Abdomen: tergites yellow with relatively few fine pale setulae especially along posterior margins of tergites 2–5; tergite 6 relatively small and narrow with long brownish setae along margin.

Hypopygium: ( Fig. 12 ) epandrium small with a fold along posterior margin and bearing long strong brown setae posterodorsally; surstylus large and broad with undulating ventral margin and a long apical seta, dorsal to this a small rectangular projection, originating from the ventromedial aspect of the epandrium; cerci small, very pale with minute setulae; postgonite moderately well sclerotized broadly triangular at base and narrow elongate distally, bearing a row of short but distinct setulae along dorsal margin; hypandrium almost rectangular with very small pregonite; phallapodeme straight rod-shaped; distiphallus mostly translucent, poorly sclerotized, elongate and tubular.

Female: very similar to male except for secondary sexual characters. Spermathecae flat and disc-shaped, pigmented with slightly darker margin; spermathecal duct entirely membranous.

Body length: male and female 1.3mm, Wing length: male and female 1.4mm.

Variation: there is some variation in size and the approximation of R 2+3 and R 4+5 such that the ratio of this distance on the costa to that between R 4+5 and M varies from 0.5–0.7; some females with narrow pale brown transverse bands dorsally on proximal tergites.

Etymology: the species epithet refers to the country of origin, this being the first species of this genus to be described from Chile.

Similar species: T. macalpinei ( Hardy 1980: 175, Fig. 71b, c) has long setae on the epandrium and a long narrow aedeagus similar to those of the new species; the surstylus is long and narrow while in T. chilensis it is short and broad, almost triangular. T. minuta ( Hardy 1980: 175, Fig. 71e–g) has the dilated hind basitarsomere and setae anterodorsally on the hind tibia. The hypopygium is also different in all respects. Apart from characters given in the key, T. chilensis differs from T. litophila and T. nigrifacies in having narrow gonites and strong epandrial setae.

Distribution: Chile.

Note. All the material of T. chilensis was initially preserved in alcohol. The full data for the specimens were supplied separately and are listed below. They were summarized to the essential information for the specimen labels as given in the text above.

1. Antofagasta, 6 km SW of Calama, 0.53 km ENE of waterfall Las Cascadas of Rio Loa, narrow irrigation ditch, parallel to Rió Loa; 22°30ʹ12.7ʹʹS 68°58ʹ27.2"W, 2168 m asl, sweeping dense vegetation of Bolboschoenus , Juncus , fruiting Asteraceae , along flowing water, downstream from end of artificial subterraneous tube supplying the ditch, semidesert biotope; 05.ii.2018, M. von Tschirnhaus leg.

2. Antofagasta, Rió Loa, gorge 3 km N Chíuchíu, 33 km ENE Calama, 22°18ʹ53.2"S 68°38ʹ53.0"W, 2602 m asl, sweeping irrigated vegetable fields with Daucus carota and Beta vulgaris and white flowering Apiaceae , east of the river, ground actually dry, 09.ii.2018, M. von Tschirnhaus leg.

3. Región de Antofagasta, Laguna Inca Coya, a large salt influenced swamp of Rió Salado within the desert adjacent to the small round Laguna Chiu Chiu, 22°20’23.8"S 68°35ʹ59.5"W, 2539 m asl, sweeping Juncus , Asteraceae , Poaceae alongside the water, 09.ii.2018, M. von Tschirnhaus leg.

4. Tarapaca, beach “Caleta de Camarones”, river mouth of Río Camarones , 133 km S. Iquique, 21°25ʹ48.5"S 70°03ʹ26.0"W, 5 m asl, sweeping near running fresh water with vegetation on gravel, mud and sand, dominant: Bolboschoenus and a salt grass, 22.ii.2018, M. von Tschirnhaus leg.

Figures

FIGURE 11. Tethysimyia chilensis sp. nov., A. holotype, male in alcohol. B. same, hypopygium lateral view. C. same posterior view. D. female paratype in alcohol. For scale see Fig. 12.

FIGURE 12. Tethysimyia chilensis sp. nov., A. holotype, male after critical point drying. B. same abdomen, enlarged. C. paratype, male hypopygium, lateral. Abbreviations as in FIGUREs 2 and 8. Scale bar = 0.1mm.