Aphaniosoma sp.

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 : 311

Aphaniosoma sp.

Fig. 7

Material: ARGENTINA, 1♁, Province Mendoza, southern shore of Rio Salado, N of road to La Lenas , a western side road of road 40, 1 km of junction, 28 km NNW' Malargue , 35°12.70'S 69°42.68'W, leg. M. von Tschirnhaus, (SDEI- MvT, 1830) .

Diagnosis: A very pale species (much exaggerated because of bleaching in alcohol) without trace of scutal vittae; 4 reclinate fronto-orbital setae decreasing in length from posterior to anterior, lateroclinate ocellars, long narrow cerci with row of fine setae along posterior margin.

The species is not named here because it is the only available specimen, and it is not in a suitable condition to ensure its long term “survival”. The description is given to establish the presence of this genus in the Neotropics and provide a basis for the study of future material should it become available.

Description

Male.

Head: all pale except for reddish ocelli; almost twice as broad as long; margins of frons converge anteriorly, at level of antennae 0.6 width that at level of anterior ocellus; gena narrow in front, deeper behind, in profile, below middle of eye, about 0.6 height of eye, with very short white setulae; occiput in profile not visible behind posterior pole of eye, postocular setulae short, in one row; mouth parts all pale; vibrissal setula moderately developed; face short, poorly sclerotized and depressed; median carina not developed; antenna pale, small, somewhat recessed, pedicel with short seta dorsally; basal flagellomere with fine pubescence along anterior margin; first segment of arista pale, second dark; chaetotaxy: 4 short fronto-orbitals reducing in size towards front and with 3 very short fine setulae in front of these; paraverticals minute and convergent; 1 inner and 1 outer vertical; ocellars short and lateroclinate; about 14 short setulae across middle of frons.

Thorax: entirely pale yellowish white; mediotergite yellow; chaetotaxy: 1 postpronotal, 1 posthumeral, 2 notopleurals, 1 postalar, 0+2 dorsocentrals, anterior about half as long as posterior, acrostichals in 4 rows, prescutellars not developed, 4 scutellars, 1 anepisternal, 1 katepisternal, minute proepisternal setula present.

Wing: veins all very pale translucent yellow; distance on costa between R 2+3 and R 4+5 about 0.4 that between R 4+5 and M; distance between cross veins about 1.3 length of posterior cross vein, which lies oblique and 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 longer than maximum diameter of tibia; claws black in apical half and pulvilli normal.

Abdomen: pale yellow; tergites with minute pale setulae, longer on lateral apical margin of tergites 5 and 6.

Hypopygium: ( Fig. 7B ) cerci triangular in profile, long and narrow, bearing long fine setulae along posterior margin (cerci directed dorsally in this specimen, but this is unlikely to be the natural position); epandrium small and pale, very narrow dorsally or divided; apical part of pregonite, narrow and curved, visible at anteroventral margin of hypopygium; apex of postgonite, short triangular, visible at posterior margin of epandrium; surstylus not identified; internal hypopygial structures not visible.

Female: unknown.

Body length: male 1.2mm, Wing length: male 1.2mm.

Distribution: Argentina.

Similar species: No other species of A phaniosoma are known from the Neotropics. Aphaniosoma frontatum Wheeler is the only Nearctic species (described from the Gulf coast of Texas) that comes closest to the Neotropics. It is quite different from the new species; it has 3 fronto-orbital setae and a pair of setae on the frons in front of the ocellar triangle; it has dark grey colouration on the occiput, dark greyish black scutal vittae and dark grey abdominal tergites; the very few acrostichals are in 2 rows.

Figures

FIGURE 7. Aphaniosoma sp. A. habitus male. B. postabdomen, lateral view, and apex of wing, enlarged.