Microsesia, Bartsch, Daniel, 2015

Bartsch, Daniel, 2015, New taxa of southern African Sesiini (Lepidoptera: Sesiidae), Zootaxa 3956 (3), pp. 428-436 : 428-429

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new gen.

Microsesia new gen.

Type species: Microsesia nana , designated here.

Description. ( Figs. 1 –4 View FIGURES 1 – 7 , 15 View FIGURES 15 – 16 ). Head: Haustellum well developed and functional; labial palpus short, straight, covered with short, somewhat rough scales, second palpomere with some bristle-like scales distally, second and third palpomere about equal in length, first one slightly shorter; frons and vertex smooth, frons about 2.5 × diameter of compound eye; pericephalic scales appressed to thorax; antenna relatively long, narrow, and somewhat clavate, in male entirely covered with appressed setae. Thorax: Dorsum and legs almost entirely smoothly scaled; mid- and hindtibia dorso-medially and distally with some erect scales; distal pairs of spurs with outer spur somewhat shorter than inner one, middle pair of spurs with outer one around half the length of inner one. Wings narrow, hindwing tornus very narrow, forewing opaque, hindwing mostly hyaline, distally scaled. Forewing venation ( Fig. 15 View FIGURES 15 – 16 ) with R 4 and R 5 arising together from cell angle, CuA 2 absent; hindwing with M 2 arising from costal one third of crossvein, M 3 and CuA 1 from a common stalk, anal veins closely approximated. Abdomen: Almost entirely smoothly scaled; anal tuft indistinct. Male genitalia ( Figs. 5–6 View FIGURES 1 – 7 ) with tegumen broad; gnathos absent; uncus short and broad, bilobed, lobes dorsally with sparse simple setae, ventro-distally with dense, strong sclerotized, thornlike, basad pointing setae; sub-scaphium rather short and broad. Valva trapezoid, dorso-distally with narrow, triangular, distad pointing protrusion; inner surface with narrow, straight, medially to ventro-distally running fold; dorso-distally of this fold a patch of strong sclerotized, thorn-like setae, a few setae of this type medially between fold and ventral margin, medially and distally covered with sparse hairs. Saccus long and slender. Juxta relatively broad slightly protruded. Phallus strong, proximally broad, coecum penis reduced, distally moderately tapering with a single row of short teeth ventrally; vesica densely covered with sclerotized spines, ventro-distally with a row of short, sclerotized teeth. Female genitalia ( Fig. 7 View FIGURES 1 – 7 ) with papillae anales long and narrow, somewhat pointed; segment eight long and narrow; apophyses posteriores about 1.5 × as long as apophyses anteriores; lamella postvaginalis well developed, triangular; ostium bursae narrow, round; antrum rather short, narrow, with narrow sclerotized ring; ductus bursae broad, caudally slightly s-curved; bursa copulatrix ovoid, with small, oval signum.

Diagnosis. Microsesia occupies a rather isolated position within the Sesiini and exhibits the following putative synapomorphies: (1) extraordinarily small species; (2) frons extremely broad with unusual ratio of width of frons and eye; (3) scales of frons and vertex as well as pericephalic scales smooth; (4) antenna long and narrow, in male entirely covered with appressed ciliae; (5) wing venation with forewing veins R 4 and R 5 from a common point, CuA 2 absent, and hindwing anal veins closely approximated.

Another important character is the well-developed, probably functional haustellum (reduced in most Afrotropical Sesiini ; present, but relatively short, weakly sclerotized in Vespanthedon Le Cerf, 1917 and Hagnogyna Bartsch, 2013; similarly well-developed in Alonina Walker, 1856 and Coccophila gen. nov.). Coccophila and Anaudia also have appressed ciliae of the male antennae, but their antennae are distinctly shorter and thicker (ciliae ventrally erect and well visible in most Sesiini ).

Several characters of the genitalia of both sexes may represent apomorphies, but these are difficult to assess because only one species is known. Putative apomorphies for the male include the trapezoidal valva with a dorsodistal triangular protrusion, and the phallus with reduced coecum penis and with a ventro-distal row of short teeth. Putative apomorphies for the female include the small, somewhat pointed papillae anales, and the broad, caudally slightly s-curved ductus bursae.

Distribution. Only very few specimens of Microsesia are known, all originate from the humid coastal and subtropical regions of southern and eastern South Africa and Swaziland.

Etymology. Ancient Greek mikros (= small), gender is feminine.