Tethysimyia nigrifacies, 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 : 323-324

Tethysimyia nigrifacies sp. nov.

Figs 15–17

Material: holotype ♁, WEST INDIES : Dominica, Portsmouth , -. vii.1979, leg. N.L.H. Krauss ( UZMC) . Paratypes: 3♀♀, same data and depository, US Virgin Islands: 1♀, St Thomas (date and collector not known) ( UZMC) .

Diagnosis: A sexually dimorphic species: black faced in the male, yellow in the female; frons projecting anteriorly; a pair of long divergent ocellars; anterior declivity of scutum yellow; mediotergite yellow.

Description

Male.

Head: yellow except for black face and contiguous anterior 2/3 of frons, posterior third of frons brown; anterior 1/3 of gena also black; ocelli reddish on a yellow ocellar triangle; frons broad, at vertex about 0.5 width of head, narrowed anteriorly, at level of antennae about 0.7 width that at level of anterior ocellus; gena narrow in front, deeper behind, in profile, below middle of eye, about half height of eye, with several scattered white setulae; occiput in profile broadly visible behind eye except at posterior pole of eye, postocular setulae in one row; mouth parts all yellow; 2 vibrissal setulae poorly developed; face short, poorly sclerotized and depressed; median carina between antennae narrow; antenna with black basal flagellomere, pedicel brown with distinct short seta dorsally; arista yellow on basal 1/3, remainder black; chaetotaxy: 2 fronto-orbitals placed on posterior half of fronto-orbital plate, with 3 short setulae in front, 1 inner and 1 outer vertical, both strong; ocellars broken; paraverticals minute and divergent; 1–2 pairs of short postocellars; about 20 distinct pale setulae scattered on frons.

Thorax: pale yellow; chaetotaxy: 1 postpronotal, 2 notopleural, 1 intrapostalar, 1 postalar, 2 dorsocentrals, anterior about 1/3 length of posterior, acrostichals in 8 irregular rows with 1 pair of developed prescutellars, 4 scutellars, 1 anepisternal, katepisternal at upper posterior corner missing (broken), and 3 setulae vertically down middle of sclerite.

Wing: veins all pale yellow; distance on costa between R 2+3 and R 4+5 about 0.5 that between R 4+5 and M; distance between cross veins about x2 length of posterior cross vein, which is about 0.4 length of apical section of vein Cu. Haltere pale yellow.

Legs: not modified except for numerous, thickened, pale, pecten-like setulae along ventral surface of hind basitarsomere; apico-ventral seta on mid tibia present and strong; claws black on apical 2/3; hind trochanter not modified.

Abdomen: all tergites yellow with numerous fine pale brown setulae especially along posterior margins, where the longer setulae are about half to 2/3 length of respective tergite.

Hypopygium: ( Fig. 16 ), epandrium small and pale, bearing a small indistinct surstylar lobe; cerci small and pale; hypandrium distinct, long and broad, viewed dorsoventrally bearing a setulose pregonite posteriorly; phallapodeme long rod-like, postgonites short, apically spatulate and curved dorsomedially with a dense margin of microsetulae; distiphallus pale, weakly sclerotized and broad basally and narrow apical section shorter than broad basal section.

Female: ( Fig. 17 ) similar to male, but head entirely yellow and frons more setulose.

Body length: male 1.3mm, female 1.4mm, Wing length: male 1.1mm, female 1.2mm.

Etymology: the species epithet refers to the black face in the male.

Similar species: T. nigrifacies is a unique species in having a black-faced male. In most respects it is closest to T. bonairensis and T. litophila , the new species described above. The important differences are in the male hypopygium, where T. nigrifacies differs in having a broader hypandrium when viewed dorsoventrally, a thicker phallapodeme; differently shaped postgonites that have a densely micro-setulose margin, and a relatively shorter and broader aedeagus.

Distribution: West Indies ( Dominica, US Virgin Islands).

Figures

FIGURE 15. Tethysimyia nigrifacies sp. nov., holotype, male. A. habitus, lateral view. B. dorsal oblique view. C. head, anterolateral view. D. same, dorsal view.

FIGURE 16. Tethysimyia nigrifacies sp. nov., male paratype.A. hypopygium, lateral aspect. B. aedeagal complex, anteroventral aspect. Abbreviations as in FIGUREs 2 and 8. Scale bars = 0.15mm.

FIGURE 17. Tethysimyia nigrifacies sp. nov., female, A. paratype from Dominica, habitus, lateral view. B. same, head, dorsolateral view. C. paratype from St. Thomas, head, anterodorsal view.