Tethina pleuralis Munari, 2010

Munari, Lorenzo, 2016, The Canacidae of the Arabian Peninsula (Diptera: Brachycera: Carnoidea), Zootaxa 4092 (4), pp. 489-517 : 505-506

Tethina pleuralis Munari, 2010

(figs. 30‒33)

Tethina pleuralis Munari, 2010: 651 [ United Arab Emirates. South of Ras Al Khaymah, coast, 25°43.66’ N, 055°52.42’ E; HT ♂, NMWC].

Distribution. Afrotropical: United Arab Emirates.

Diagnosis. Body length 1.45−2.73 mm; small fly (fig. 30) with grey body, pale yellow striped pleura, and yellowish legs; scutellum with very wide, brown spot with indefinite outline (fig. 31); setal vestiture white to pale yellow; wings weakly infuscate on the entire anterior half. Head entirely pale yellow to whitish; 3 pairs of minute, inclinate, interfrontal setae; antenna yellow, arista infuscated in the apical half; eye strongly oblique, its longest diameter 1.56–2.36 times as long as the height of the gena; gena whitish, with broad, longitudinal, translucent stripe; proboscis with labella about as long as or slightly longer than the length of the buccal cavity; thorax grey, with pale yellow postpronotal lobe; pleura with large stripes and irregular spots of the same colour as the postpronotal lobe; acrostichal setulae long, arranged in 4 rows; acrostichal prescutellars fairly long; intra-alars and the two accompanying rows of mesonotal setulae irregular; posterior third of scutum strongly setulose; legs entirely pale yellow, only the apical tarsomere strongly infuscated; wing weakly infuscated on entire anterior half; black macula on the dorsal base of vein R1 (fig. 30); crossveins depigmented, without milky halo; syntergite 1+2 broadly yellowish; male terminalia with surstylus subtriangular, tapered apically in lateral view (fig. 32), bearing wide, mesal lobe in posterior view (fig. 33), with several setae on mesal side.

Remarks. Munari (2010) noticed that this species is closely related to Tethina dunae . It differs mainly in having broader, roundish, scutellar spot, with noticeably vague outline (clearly subrectangular to subtrapezoidal, with well defined outline, in T. dunae ). Furthermore, the surstylus is sharply subtriangular in lateral view, noticeably long, narrow, and tapered apically, rather than regularly lobe-shaped as in T. dunae . Conversely, the external male terminalia are quite similar in posterior view to those of T. dunae . The characteristic white to yellow pattern of pleura and postpronotal lobe (white to yellow striped pleura and yellow postpronotal lobe, the latter strongly contrasting with the rest of the greyish scutum) are also quite similar in the two species. Despite the overall similarity between these two species, Munari (2010) guessed that the above-mentioned differences represent, in all probability, significantly consistent characters rather than being due to intraspecific or geographic variation. Therefore, these two taxa should be regarded as two distinct species, rather easily recognizable, though, on the basis of the chromatic pattern of the scutellum and the morphology of the surstylus in lateral view.