Tethysimyia bonairensis, 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 : 314-317

Tethysimyia bonairensis sp. nov.

Figs 8–10

Material: holotype ♁, BONAIRE: Washington Slagbaai , Playa Chikitu, 12–19.xii.2022, 12.2791°N, 68.3485°W, leg. O. Vorst & V. J. Kalkman, Malaise trap, BON 2022-2023.8, Museum Leiden ( RMNH), critical point dried and card pointed . Paratypes: 2♁♁, same data, dissected and preserved in glycerine tube; 55♁♁, 124♀♀, same data, preserved in alcohol; 11♁♁ and 10♀♀, same data, critical point dried and card pointed; 6♁♁ and 8♀♀, same data, critical point dried and card pointed ( MJE coll.); 1♁, 1♀, Rincón , BOPEC, 19–27.xii.2022, 12.2264°N, 68.3814°W, leg. V. J. Kalkman, Malaise trap, BON2022-2033.9, Museum Leiden ( RMNH), preserved in alcohol. ( BOPEC refers to the old oil terminal on the north coast of Bonaire) .

Diagnosis: an entirely yellow species in both sexes with few external characters to distinguish the females from those of congeners found in adjacent territories. The male postabdomen, although similar to that of T. litophila sp. nov. and T. nigrifacies sp. nov., differs from both in having a narrower and longer aedeagus and in the shape of the epandrium and pregonite. The postgonite and cerci are absent.

Description

Male.

Head: entirely yellow, higher than long; frons about 3 times as broad as eye and produced anterodorsally beyond eye margin; at vertex about 0.7 width of head; frons narrowed anteriorly, at level of antennae about 0.8 width that at level of anterior ocellus; ocelli translucent; eye oval, lying oblique; gena narrow in front, deeper behind, in profile, at middle about equal to height of short diameter of eye, and with several scattered minute pale setulae; occiput in profile broadly visible behind eye except at posterior pole of eye; postocular setulae in one row; mouth parts all yellow; 3 vibrissal setulae well developed; face short, poorly sclerotized and depressed; median carina between antennae narrow, not quite reaching mouth margin; antenna only a little recessed in shallow fossa; yellow with short seta dorsally on pedicel and postpedicel with fringe of fine setulae; arista bare, yellow on basal 1/3 to 2/5, remainder black; chaetotaxy: 2 fronto-orbitals placed on posterior half of fronto-orbital plate, with 3 very short and fine setulae anterior to these; 1 inner and 1 outer vertical; ocellars about as long as anterior orbital; paraverticals absent; about 18 fine, pale setulae scattered on frons.

Thorax: pale yellow; chaetotaxy: 1 postpronotal, with short setula adjacent, 2 notopleural, 1 intrapostalar, 1 postalar, 2 dorsocentrals, anterior about 1/3 length of posterior, acrostichals in 8 irregular rows, prescutellar pair distinct; 4 scutellars, 1 anepisternal, 1 katepisternal at upper posterior corner and 3 setulae on middle of sclerite.

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 x2 length of posterior cross vein, which is about 0.4 length of apical section of vein Cu. Haltere pale yellow.

Legs: all pale with pale setulae; apico-ventral seta on mid tibia present, dark and long; hind tibia with row of short setae along anterodorsal aspect; 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 at most 1/2 length of respective tergite.

Hypopygium: ( Fig. 9 ), epandrium small and pale, bearing a long narrow rod-like surstylus; cerci absent; hypandrium, viewed dorsoventrally, long and narrow, bearing a setulose pregonite posteriorly; phallapodeme long rod-like; distiphallus pale almost translucent, weakly sclerotized, only a little broad basally, long and narrow apically, with this section about twice as long as broader basal section.

Female: ( Fig. 10 ) similar to male, except for hypopygium; spermatheca in the shape of a circular disc with narrow black margin.

Body length: male 1.2mm, female 1.4mm, Wing length: male 1.0mm, female 1.3mm.

Etymology: the species epithet refers to the island of Bonaire where the species was found.

Similar species: T. nigrifacies described below, has a black-faced male, which also has a shorter and broader aedeagus; the female is very similar to the female of T. bonairensis . T. litophila , the other new species described below is not entirely yellow, having a dark patch on the anterior declivity of the thorax, a dark mediotergite and brown transverse bands on the abdominal tergites. All three species have a very similar structure to the male hypopygium, with the differences being in the length and relative width of the aedeagus and the shapes of the gonites.

Distribution: Bonaire.

Figures

FIGURE 8. Tethysimyia bonairensis sp. nov. A. holotype, male habitus. B same, postabdomen in situ, enlarged, lateral view. C. female paratype, head, dorsal view.

FIGURE 9. Tethysimyia bonairensis sp. nov. Paratype, male hypopygium. Top–lateral view, bottom–dorsal view.Abbreviations as in Fig. 2, aed–aedeagus. Scale = 0.15mm.

FIGURE 10. Tethysimyia bonairensis sp. nov., A. paratype, female habitus. B. another specimen female paratype, abdomen enlarged, lateral view; note the disc-shaped spermatheca with a black margin, deep to tergite 6.