Yukikoa nishimotoi Nakamura, 2023

Nakamura, Ryo & Kubota, Kôhei, 2023, Taxonomic study of the Japanese endemic genus Yukikoa M. Satô (Coleoptera, Cantharidae) with descriptions of two new species, Zootaxa 5351 (5), pp. 581-589 : 585-586

Yukikoa nishimotoi Nakamura sp. nov.

Japanese name: Maeguro-shiributo-jôkai

( Figs. 2 , 4a–c , 6 )

Type material. Holotype, male ( KURA), “ JAPAN: Honshu , Fukui-ken ,/ Minamiechizen-chô,/ Mt. Somayama, alt. 300–490 m / 5. IV. 2022 Shôma Nishimoto leg./dzffĕ南KAEffl NƜ”.

Description (holotype). Male. Body small and slender. BL 9.9 mm. Body almost blackish brown; mandibles, apex of each femur, and elytra yellowish brown. Body closely covered with brown pubescence.

Head slightly shorter than width, dorsum depressed between antennal sockets; eyes relatively large, globular and prominent, interocular distance 2.58 times as wide as the diameter of an eye; mandible arcuate and pointed at apex; each of palpomere with triangular apical segment; antennae reaching 3/5 of elytra, filiform but weakly serrate in basal three segments, comparative lengths of antennomeres as follows: 2.46: 1.00: 1.42: 1.85: 1.79: 1.88: 1.88: 1.85: 1.69: 1.54: 1.81.

Pronotum transverse trapezoidal, widest at posterior angles, PW/HW 1.35, PW/PL 1.69, anterior margin weakly emarginate, posterior margin gently protruding in lateral halves and emarginate in the middle, lateral margins almost straight but feebly sinuate in apical 1/4, all angles obtuse and rounded, disc almost flat though provided with a hourglass-shaped convex area in the middle with a medio-longitudinal furrow not reaching the anterior and posterior margins. Scutellum triangular with blunt apex. Elytra long, almost parallel in basal 1/5, then dilated posteriad with the broadest point at posterior 1/3, apex normally rounded, HEW/PW 1.14, MEW/PW 1.55, EL/HEW 2.76, EL/ MEW 2.03. Legs slender, each femur mostly straight, each tibia mostly feebly arcuate.

Genitalia relatively elongate; each ventral process of paramere moderately slender, broad at apical portion and forming a weak hook with blunt tip towards ventral side; dorsal plate of paramere with a deep U-shaped incision in the middle of anterior margin, lateral sides weakly narrowed anteriorly, ventral surface provided with a transverse protuberance at the middle of each side; each laterophyse rather distant, slender with an oblique apex in ventral and dorsal view, and stout and curved in lateral view, with the tip towards the protuberance on the ventral side of dorsal plate, the apex reaching the same level of ventral process and the protuberance on the ventral side of dorsal plate.

Female. unknown.

Differential diagnosis. Yukikoa nishimotoi sp. nov. is readily distinguishable from all the congeners by blackcoloured head and pronotum. Though the dorsal plate of male genitalia is similar to those of Y. masatakai Takahashi, 2003 from Nagano Pref. and Y. wittmeri ( Nakane, 1963) from Ôsaka Pref., the new species differs from them by longer elytra (EL/MEW> 2.0, EL/HEW> 2.7 in Y. nishimotoi ; EL/MEW <1.9, EL/HEW <2.6 in Y. wittmeri and Y. masatakai ).

Distribution. Japan (Honshu, Fukui Pref., Mt. Somayama).

Collecting circumstance. According to the collector, the holotype was collected by sweeping large white flowers in the evening.

Etymology. The specific name is in honor of Mr. Shôma Nishimoto, who collected the holotype of this remarkable new species.

Figures

FIGURE 6. Distribution map of Yukikoa species in Japan.

FIGURES 1–2. Holotypes of Yukikoa spp., male, dorsal habitus. 1, Y. mashimai Nakamura sp. nov.; 2, Y. nishimotoi Nakamura sp. nov. Scale bars: 3.0 mm.

FIGURES 3–4. Male genitalia of Yukikoa spp., ventral view (a), lateral view (b), dorsal view (c), and apex of ventral process in ventro-lateral view (d). 3, Y. mashimai Nakamura sp. nov.; 4, Y. nishimotoi Nakamura sp. nov. Scale bars: 1.0 mm.