Smaragdina bienkowskii Romantsov & Bezděk, 2025

Smaragdina bienkowskii Romantsov & Bezděk , sp. nov.

( Figs 7 View FIGURES 7–15 , 16 View FIGURES 16–19 , 22 View FIGURES 20–24 )

Type locality. Vietnam, Hòa Bình Prov., Mai Chau Vill., Eco Homestay , 20°38'56.6"N, 105°03'59.2"E GoogleMaps .

Type specimens. Holotype ( Fig. 7 View FIGURES 7–15 ): ♂ ( PRCS), “N Vietnam, Hòa Bình Prov., Mai / Chau Vill., Eco Homestay / N 20°38'56.6", E 105°3'59.2" / 170 m, at light, / 20.IV.2019 P. Romantsov leg. [w, p]” . Paratype: 1 ♀ ( ZIN), same data as in holotype. The type specimens are provided with one additional printed red label: “ Holotypus [or Paratypus] / Smaragdina bienkowskii / Romantsov & Bezděk, sp. n. / det Romantsov & Bezděk, 2025 ” .

Description. Measurements. Male: 6.3 mm ( holotype), female: 6.5 mm. Body elongate. Head brown. Pronotum brown, but slightly lighter than head. Scutellum brown. Elytra light brown. Underside and legs brown. Antennae brown, antennomere IV with inner dorsal half darkened, V–VI brownish ventrally and laterally, dorsally black, VII–XI black.

Male( holotype, Fig.7 View FIGURES 7–15 ). Head large, impunctate,1.38 times narrower than pronotum.Labrum with slightly rounded apical margin, surface slightly convex, lustrous, impunctate with several setae at anterior third. Frontoclypeus with lustrous and slightly convex clypeal part, anterior margin slightly concave. Frons slightly convex with depression between eyes, surface near eyes covered by very fine microsculpture without setae. Frontal tubercles absent. Eyes large, slightly bean-shaped with small notch on inner margin, 1.33 times as long as wide. Interocular space narrow, 0.77 times as wide as transverse diameter of eye and about 3.3 times narrower than head with eyes. Vertex slightly convex, lustrous and impunctate.Antennae moderately short, about 2.7 times shorter than body.Antennomere I large, stout, II pentagonal, III shortest, slightly widened at apex, IV–X strongly flattened and serrate, last antennomere spear-shaped with elongate sharp apex. Antennomeres I–III lustrous with sparse, short, erected setae on inner edge, IV–XI dull with slightly rugose surface covered with short adpressed setae and with two or three longer erected setae on anterior angles. Length ratio of antennomeres I–XI as 11: 5: 4: 9: 9: 9: 9: 9: 8.5: 8: 13, width ratio as 6: 5: 3.5: 8: 9: 9: 8: 7: 8: 7: 6.5. Penultimate maxillary palpomere slightly wider and about 1.4 times longer than next one, apical palpomere with truncated apex.

Pronotum convex, transverse, 1.75 as wide as long, about as wide as elytra on base, widest at anterior third. Anterior margin slightly convex in middle, lateral margins rounded, posterior margin almost straight near lateral angles, in middle of pronotal base distinctly protruded opposite scutellum. Surface lustrous, very sparsely covered with small punctures. Anterior angles obtusangulate with rounded tip, posterior ones almost imperceptible, widely rounded. Anterior angles bearing setigerous pore with rather long, curved pale seta. Anterior margin bordered near angles, in middle part unbordered; posterior margin thinly bordered and lateral margins widely bordered. Scutellum triangular, approximately as wide as long, surface lustrous and impunctate, scutellar apex very weakly elevated upon level of elytra.

Elytra subcylindrical, 1.57 times as long as wide. Basal margin bordered only near shoulders, lateral margins widely bordered in anterior half and thinly bordered in posterior half. Elytral surface covered with confused punctures in basal part but arranged in more or less distinct rows in middle and lateral parts. Punctures at basal third rather large, then gradually diminishing and disappearing in apical slope. Epipleura glabrous, moderately wide in anterior third, then rather suddenly narrow and disappearing at level of metacoxae. In lateral view, lateral margin of elytra moderately lobed below shoulders. Pygidium with rounded apex, not exposed. Legs robust. All tibiae almost straight, noticeably widened towards apex. Tarsomeres I of all legs slightly narrower than III. Length ratio of protarsomeres I–III and V as 15: 12: 14: 22; width ratio of protarsomeres I–III as 12: 11: 14. Claws simple but slightly thickened at base.

Aedeagus ( Fig. 16 View FIGURES 16–19 ) rather short and wide with finger-shaped emarginated apex. Underside of aedeagus slightly convex without distinct depressions or ridges. In lateral view apex strongly bent ventrally. Length of aedeagus 1.7 mm, width 0.5 mm.

Female. Antennae less serrated. Eyes smaller and less convex than in male, interocular space somewhat wider (1.05 times as wide as transverse diameter of eye and about 2.57 times narrower than head with eyes). Pygidium of female with slightly truncated apex, so its posterior margin looks almost straight with very faint, almost imperceptible notch in middle. Spermatheca with long frizzy ductus ending by rather large spindle ( Fig. 22 View FIGURES 20–24 ). Length of spermatheca (excluding ductus) 0.4 mm.

Variability. Coloration of female similar as in holotype but metepisterna slightly darkened.

Differential diagnosis. Smaragdina bienkowskii sp. nov. belongs to the S. sikkimia species group (which also includes S. constrictifrons , S. sikkimia and S. vietnamica ). This group is characterized by a yellowish-brown to brown dorsum, large eyes, and a narrow frons, noticeably narrower than the transverse diameter of the eye in males and approximately equal in females, as well as a finger-shaped apical process of the aedeagus. Smaragdina sikkimia has an aedeagus very similar to that of S. bienkowskii sp. nov., but it differs in having a black or darkened ventral side and tarsi. Additionally, males of S. sikkimia have a narrower frons (0.60-0.65 as wide as transverse diameter of eye, compared to 0.77 in S. bienkowskii sp. nov.). The aedeagus of S. sikkimia is depressed below the gonopore, therefore, in lateral view, it appears thin and sinuous in its preapical part ( Fig. 18 View FIGURES 16–19 ). Females of S. sikkimia differ in the shape of spermatheca ( Fig. 23 View FIGURES 20–24 ). In the identification keys for Oriental Smaragdina by Medvedev (2010) and Warchałowski (2012), S. bienkowskii sp. nov. would be placed near S. constrictifrons . However, S. constrictifrons differs from S. bienkowskii sp. nov. by having an apical process of the aedeagus that is toothed on each side and not emarginated on the apex. All species in the S. sikkimia species group can be identified using the key provided below.

Smaragdina diversiceps (Pic, 1941) and S. fulvitarsis Medvedev, 1992 belong to another large Smaragdina species complex, characterized by a with wide frons (significantly wider than transverse diameter of the eye, even in males, and especially in female), but they have somewhat similar shapes of aedeagus (see the drawings in Medvedev 2010a). However, both these species are smaller in size ( S. bienkowskii sp. nov.: 6.3–6.5 mm, S. diversiceps : 4.1–6.1 mm, S. fulvitarsis : 4.0–4.7) and also differ from S. bienkowskii sp. nov. in couloration: S. diversiceps has a black head, underside and humeral spot on elytra, and S. fulvitarsis has a darkened metasternum.

Due to their narrow frons, Smaragdina oculata Medvedev, 1988 and S. megalayana Medvedev & Kantner, 2002 , are also externally similar to S. bienkowskii sp. nov. However, they differ in the shape of the aedeagus, which has a triangular apex with a pointed tip. Smaragdina tamdaoana Medvedev, 2010 , known only from females and also having brown upperside, is easily distinguished from S. bienkowskii sp. nov. by its very wide frons, which is more than twice as wide as the transverse diameter of the eye.

Etymology. The new species is dedicated to Andrzej O. Bieńkowski, well known specialist in Chrysomelidae .

Distribution. Vietnam.