Diduga siamensis Bayarsaikhan & Heppner 2024, sp. nov.

Diduga siamensis Bayarsaikhan & Heppner, sp. nov. urn:lsid:zoobank.org:act: 43781727-C142-4EF4-9F60-B6742FFD5B21 (Figs 1, 3) Type materials. Holotype. [THAILAND] 1♂, Mae Hong Son, Pang Mapha (Soppong), 27–30 Jul 2009, 605 m, J.B. Heppner, adult no. FLMNH-MGCL1174139 and genitalia slide no. UB˗12967 (deposited in MGCL). Diagnosis. By the wing pattern of this species, it is hardly distinguishable from many congeners of Diduga. The genitalia structure of the new species is similar to D. flavicostata (Snellen), and both species have a large strong spine-like apical structure and a membranous saccular process in the symmetric valva; and the saccus is broadly U-shaped. However, the new species differs from D. flavicostata by having a tapering uncus; and spine-like apical process of valva is strongly sclerotized, weakly waved; apical half of costal margin of valva membranous; and the aedeagus vesica with a large strong spine-shaped cornutus and a bundle of short spines in the male genitalia. In D. flavicostata, uncus is irregularly conic, with a thin hook-shaped apical process; and the apex of valva sclerotized, weakly curved, strongly pointed (spine-like), it is half size of valva length; sclerotized costal margin of valva broadly angled in medial area; and the aedeagus vesica with two slender spine-shaped cornuti (Bayarsaikhan et al. 2023a: 4, fig. 2c). Description. Adult (Figure 1). Length of forewing 11 mm in male. Head and patagium pure yellowish. Proximal end of tegula pure yellowish and distal end dark brownish. Thorax dark brownish. Forewing ground color dark brownish, with pure yellowish, broad costal and terminal margin, it edged by whitish slender line; with small, dark brown dots in costal and terminal border; cilia pale yellowish. Hindwing ground color pale brown; cilia pale brown. Abdomen pale and anal tuft pale yellowish in male. Male genitalia (Figure 3). Uncus tapering, with a small apical spine.Anal tube membranous and scaphium weakly sclerotized. Tegumen triangular, almost same length with uncus. Valvae symmetric, stout, with a strongly sclerotized spine-like apical process, almost same length with uncus; apical half of the costal area of valva membranous, with sclerotized basal area of costal margin of valva; apical saccular process membranous, a half-length of apical process of valva. Juxta strongly sclerotized, with weakly triangular apex. Vinculum short, weakly sclerotized; saccus broadly “V”˗shaped. Aedeagus stout, weakly sclerotized, and vesica with a bundle of diverse sized and shaped cornuti. Female genitalia. Unknown. Distribution. Thailand (Mae Hong Son Province). Etymology. The species name refers to “ Siam ”, which was the official name of mainland Thailand until 1939.