Xanthetis spurrelli (Hampson, 1914)

Volynkin, Anton V. & László, Gyula M., 2020, Revision of the genus Palaeugoa Durante, 2012, with descriptions of seven new species (Lepidoptera: Erebidae: Arctiinae: Lithosiini), Ecologica Montenegrina 36, pp. 53-77 : 55

The P. spurrelli species-group

Diagnosis. The members of the species-group are characterized by the bright yellow or pale orange wing and body colouration. In the male genitalia, the species-group is distinguished by the combination of the following features: (1) the anellus is membranous (it is partially covered in very small spinules only in P. smithi ); (2) the transtillae bear large lobe-like processes which are interconnected by a thick-walled membrane or fused basally; (3) the cucullus is broad, with a relatively long membranous ventral part; (4) the costal process may bear an elongate but short crest.

Description. External morphology of adults. Small moths with forewing length 6.5–12 mm in males and 9.5–11 mm in females (the female of P. megala is unknown). Sexual dimorphism limited: females slightly larger than males with slightly longer and broader forewing. Antennae of both sexes sparsely ciliate. Body and wing colouration varies from bright yellow to pale orange with some pinkish suffusion in certain species. Forewing pattern diffuse, brownish. Subbasal line shortly zigzagged, sometimes interrupted into series of dots. Antemedial lines irregularly undulate, interrupted, consisting of series of dots. Medial line more or less parallel with and running close to the antemedial line, irregularly undulate, may be interrupted at veins. Postmedial line irregularly zigzagged, strongly curved outwards opposite the cell, its posterior end curved towards tornus. Subterminal line broad, irregularly undulate, running parallel with the postmedial line, interrupted into series of spots of different sizes. Terminal line is represented by a row of small dots at veins which sometimes connected to each other by a pale suffusion. Cilia colouration as forewing ground colour. Hindwing considerably paler than forewing, without pattern.

Male genitalia. Uncus short, dorso-ventrally flattened, broad at base, tapered distally, rounded apically, weakly sclerotized, sparsely setose, fully fused with tuba analis. Tuba analis thick, membranous, subscaphium weakly setose. Tegumen short and narrow. Anellus membranous (weakly spinulose in P. smithi ). Juxta broad but short, ribbon-like, weakly sclerotized, in some species with a conspicuous medial process directed ventrally. Vinculum short, broad, U-shaped. Transtillae with large lobe-like flattened processes, which may be connected with thick-walled intrategumenal membrane or fused into one plate (as in P. smithi ). Valva elongate, moderately broad. Costa with an elongate but short transverse crest on its inner surface (absent in P. camerunensis and P. smithi ). Cucullus broad, setose, with large membranous ventral part. Sacculus narrow, with elongate and apically pointed distal process, in some species (viz. in P. smithi and P. megala ) also with an elongate and apically pointed medial process directed postero-dorsally. Aedeagus elongate and narrow, nearly straight, without processes (except in P. camerunensis where slightly sinuous bearing a plate-like medio-dorsal crest). Vesica relatively short, with several short granulated diverticula, in some species ( P. smithi and P. megala ) also with one or two elongate diverticula bearing one or a few spines apically. Distal plate of vesica absent. Female genitalia. Papillae anales rectangular with rounded corners, weakly setose. Apophyses posteriores long and thin. Apophyses anteriores very short and thin (in P. camerunensis and P. smithi ) or fully reduced (in P. spurrelli and P. secunda ). Postvaginal area of 8 th abdominal segment weakly sclerotized, rugose and weakly dentate, or thick-walled membranous and slightly rugose (in P. camerunensis ). Ostium bursae moderately broad, with membranous dorsal margin; antevaginal plate broad but very short, band-like, weakly sclerotized. Ductus bursae short, narrow, thick-walled membranous, longitudinally rugose. Corpus bursae elliptical, posterior end moderately sclerotized and rugose; medial section weakly sclerotized, longitudinally rugose and densely covered in short spinules; anterior section densely spinulose or scobinated. Appendix bursae broad, globular or elliptical, membranous or weakly setose, erected laterally, with basal section narrow, weakly sclerotized and rugose.