Euconnus (Cladoconnus) rudimentalis, Jałoszyński, 2019

Jałoszyński, Paweł, 2019, The first Korean species of Euconnus (Cladoconnus), with a synopsis of the E. ussuriensis species group (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4615 (3), pp. 481-488 : 485-486

Euconnus (Cladoconnus) rudimentalis n. sp.

( Figs 5 , 22–26 )

Material studied. Holotype: ♂ ( SOUTH KOREA, SOUTH GYEONGSANG PROV.): “ Samjeong Ri / Macheon Myeon / Cheonla-buk Do ” [white, printed], “S-KOREA / 14. vii. 1991 / S. Nomura leg.” [white, printed], “ EUCON- NUS / ( CLADOCONNUS ) / rudimentalis m. / P. Jałoszyński, 2019 / HOLOTYPUS ” [red, printed] ( NSMT).

Diagnosis. Endophallus with a pair of asymmetrical, vestigial sclerites fused at base and placed at base of ventral apical plate.

Description. Body of male ( Fig. 5 ) elongate but moderately slender, strongly convex, with long appendages, BL 1.80 mm; cuticle glossy, pigmentation dark brown, head and pronotum slightly darker than elytra, vestiture of setae yellowish.

Head weakly and evenly convex, slightly bulging posterodorsad, broadest at eyes, HL 0.38 mm, HW 0.38 mm; tempora in dorsal view slightly more than twice as long as eyes; vertex and frons confluent, weakly and evenly convex; supraantennal tubercles small and feebly elevated. Eyes moderately large, coarsely faceted, distinctly but not strongly projecting laterad from the head silhouette. Punctures on vertex and frons inconspicuous, small and sparse; setae short and sparse, suberect, denser and longer on vertex and tempora. Antennae slender, AnL 1.03 mm; antennomeres I–II each strongly elongate, III indistinctly elongate, IV–V each about as long as broad, VI indistinctly transverse, VII distinctly transverse, asymmetrical, with its mesal margin slightly projecting mesad, VIII strongly modified, at base broader than VII, strongly elongate, with its mesal margin strongly concave and with strongly projecting mesal proximal corner, mesal distal corner not projecting, antennomere IX moderately modified, distinctly shorter than VIII, with its mesal margin nearly straight and only its mesal distal corner slightly projecting, X with slightly oblique basal and distal margins, indistinctly shorter than IX, XI longer than VIII but shorter than IX–X combined, about twice as long as broad.

Pronotum broadest in front of middle, PL 0.43 mm, PW 0.40 mm; anterior margin weakly arcuate, lateral margins rounded in anterior half and slightly sinuate in posterior half, posterior corners slightly obtuse-angled, blunt. Pronotal base with narrow but distinct median longitudinal wrinkle flanked by a pair of large pits, each posterior corner with a short and fine sublateral carina and large pit between carina and lateral margin; additionally behind each large lateral pit there is a smaller, indistinct pit. Punctures on pronotal disc slightly more distinct than those on frons and vertex but obscured by dense suberect setae mixed with thick bristles.

Elytra oval, broadest slightly in front of middle, EL 1.00 mm, EW 0.75 mm, EI 1.33; basal impressions deep, humeral calli prominent, elytral apices separately rounded. Punctures on elytral disc inconspicuous, larger than those on head and pronotum but superficial and with diffuse margins; setae long, sparse and erect. Hind wings long, functional.

Legs moderately long and slender, unmodified except for the distal third of each protibia that bears a patch of dense spatulate setae on its mesal margin.

Aedeagus ( Figs 22–25 ) elongate but not slender, AeL 0.45 mm; median lobe approximately drop-shaped, broadest near proximal third, rapidly narrowed in distal half, with dorsal apical plate subtrapezoidal, with narrowly truncate apex; ventral apical plate with arrowhead-shaped apex; endophallus with a pair of short asymmetrical sclerites fused at base; parameres slender, in lateral view strongly curved, each with one apical and two subapical setae.

Female. Unknown.

Distribution ( Fig. 26 ). South Korea.

Etymology. The name rudimentalis refers to vestigial endophallic sclerites.

Remarks. The only known male of this species is distinctly smaller than those of its Far Eastern congeners; otherwise it does not differ in any external characters. The endophallus of E. rudimentalis is unique in being the sim- plest of all Cladoconnus species known; it is reduced to a pair of short stumps at base of the ventral apical plate. The type locality is Samjeong (= Sancheong) at the northern foot of Mt. Jirisan, N35.352563, E127.645132 (S. Nomura, email to PJ dated 28.04.2019).

Figures

FIGURE 26. Distribution of Far Eastern Cladoconnus species.

FIGURES 1–5. Dorsal habitus of Far Eastern Cladoconnus species. Euconnus ussuriensis Kurbatov, male (1); E. matsuae Hoshina, male (2); E. nakahamai Hoshina & Miyata, male (3) and female (4); E. rudimentalis n. sp., male (5).

FIGURES 22–25. Aedeagi of Far Eastern Cladoconnus species in ventral (22, 24) and lateral (23, 25) views. Euconnus rudimentalis n. sp., holotype (22–25).