Neolucanus kontumensis Yamamoto & Pham, 2025

Neolucanus kontumensis Yamamoto & Pham , sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:B76C3F85-8340-4BF4-8A41-0E48341C64EF

( Figs 1–7 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 View Figure 7 )

Neolucanus sp. : Tsuchiya 2021: 17 (figured, see fig. 205), 84 (catalogue).

Type material. Holotype ( Figs 1A–C View Figure 1 , 2A View Figure 2 , 3 View Figure 3 , 5 View Figure 5 , 6 View Figure 6 ): ♂, “C. Vietnam: / Kon Tum, / Dak Plo / March 2024 ” ( IEBR) . Paratypes (5♂♂, 2♀♀; all in IEBR) : 3♂♂ (one specimen damaged without legs), same data as the holotype ; 2♂♂, 2♀♀, “C. Vietnam: / Kon Tum, / Ngoc Linh / April 2024 ” .

Diagnosis. Within the 8 named species in the group worldwide, the closest relative of the new species is Neolucanus didieri Lacroix, 1972 from South Vietnam ( Lacroix 1972; Schenk 2014; Tsuchiya 2021; Huang & Chen 2024), from which N. kontumensis sp. nov. ( Figs 1–7 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 View Figure 7 ) differs in its larger body size, considerably smaller head and pronotum, more transverse pronotum, more elongated elytra, shape and location of the protibial teeth, and color pattern of the elytra (the new species has a narrow and subparallel-sided blackish band along the elytral suture and irregularly blackish portion obliquely near the basal portion of the elytra).

Description of holotype ( Figs 1A–C View Figure 1 , 2A View Figure 2 , 3 View Figure 3 , 5 View Figure 5 , 6 View Figure 6 ). Size small for the genus, body with mandibles (BL) 34.9 mm long, widest at anterior 1/3 of elytra. Measurements of other body parts in millimetre (mm): BLM, 29.5; BW, 14.1; ML, 5.4; HL, 4.4; HW, 10.6; PL, 8.1; PW, 14.1; EL, 18.0; EW, 14.0.

Body ( Fig. 1A–C View Figure 1 ) elongate-oval, about 2.5 times (with mandibles) longer than wide. Surface ( Figs 1A, C View Figure 1 , 2A View Figure 2 ) with dorsum glabrous, somewhat glossy, weakly sparsely punctate; ventral side partially with yellowish pubescence sparsely present on legs and thoraxes. Color uniformly blackishbrown to black, but peculiar vivid color pattern on elytra (i.e., ground color yellowish-reddish orange with clearly marked large T-shaped pattern in black on entire elytra with inside of base irregularly collapsed; Figs 1A View Figure 1 , 2A View Figure 2 ).

Head capsule ( Figs 1A–C View Figure 1 , 2A View Figure 2 , 3 View Figure 3 ) small, transverse rectangular, about 2.4 times as wide as long, widest across ocular canthi, maximum width moderately narrower than that of pronotum or elytra; anterior margin broadly concave, with slightly produced clypeus; pre-ocular margin with canthus well developed, flattened, extending laterally, with broadly arcuate lateral margin, without posterior angle ( Fig. 3A View Figure 3 ); postocular margin nearly straight, very weakly arcuate; forehead and vertex with large and shallow depression forming not well-marked inverted triangle. Eyes ( Figs 1A–C View Figure 1 , 2A View Figure 2 , 3 View Figure 3 ) moderately large, each completely margined and bordered with developed ocular canthus. Mandibles ( Figs 1A–C View Figure 1 , 2A View Figure 2 , 3 View Figure 3 ) short, slightly longer than head but apparently much shorter than pronotum, semicircular in dorsal view (but dorso-laterally gouged medially), rather strongly up-curved in apical half in lateral view, lacking uprising teeth dorsally; inner margin dentate, each with eight small teeth of irregular size are arranged in row, basal two fused, largest; surface uniformly finely punctured. Antennae ( Fig. 3 View Figure 3 ) composed of ten antennomeres, last three pubescent and lamellate, forming distinct antennal club; antennomere 7 sharp at inner apical angle. Mentum ( Fig. 3B View Figure 3 ) transverse, semi-ellipse, about 2.8 times wider than long; surface covering with large punctures, with dense yellowish setae especially on anterolateral areas. Submentum inverted trapezoidal, with fine setigerous punctation sparsely.

Pronotum ( Figs 1A View Figure 1 , 2A View Figure 2 , 3A View Figure 3 ) transverse, compact, about 1.7 times wider than long, widest near basal 1/3; anterior margin broadly concaved, with median area only gently produced anteriorly; pronotal anterior angles roundly pointed; lateral margins in apical 3/4 (before lateral angle) broadly arcuate, only weakly narrowed apically; basolateral (posterolateral) margins between lateral angles and posterolateral angles obliquely truncate, forming blunt, roundly obtuse lateral angles; posterolateral angles obtusely angulate; posterior margin weakly bisinuate; disc leathery, uniformly evenly covered with fine punctation and micro-reticulation. Prosternal process between procoxae ( Figs 1B View Figure 1 , 3B View Figure 3 ) strongly produced, gradually expanded posteriorly, with rounded apex. Scutellum ( Fig. 3A View Figure 3 ) subtriangular, uniformly black, glossy; surface with basal area sparsely punctured whereas remaining areas smooth.

Elytra ( Figs 1A View Figure 1 , 2A View Figure 2 ) rather long, elongate-oval, about 1.3 times longer than wide, broadest in anterior 1/3, with width subequal to pronotum; humeri obtusely rounded; lateral margins narrowly explanate, broadly arcuate; surface evenly covered with fine punctures.

Legs ( Figs 1A–C View Figure 1 , 2A View Figure 2 , 3 View Figure 3 ) short, robust. Protibiae straight, thick, flattened, gradually widened apically; outer margin on anterior half with four large acute teeth including protibial bifurcate apex ( Fig. 3A View Figure 3 ). Mesotibiae straight, with row of yellowish dense microsetae along inner edges; outer margins without external spines, apices each with one large apical spine outward and 2 spurs inward. Metatibiae similar in size and structure with mesotibiae (but with shorter apical outer spines).

Abdomen ( Fig. 1B View Figure 1 ) short, broad, strongly narrowed posteriorly. Ventrite V about 1.6 times as long as ventrite IV, with feebly medially emarginate apex. Tergite VIII ( Fig. 5A View Figure 5 ) semicircular, with membranous band along basal (anterior) margin, with incised longitudinal membranous area at middle of anterior half. Sternite VIII ( Fig. 5B View Figure 5 ) strongly transverse, weakly emarginate along anterior margin medially. Pleurite IX ( Fig. 5C View Figure 5 ) not conterminous dorsally, well separated by hyaline membranous area. Sternite IX ( Fig. 5D View Figure 5 ) weakly sclerotized along posterior margin with membranous short longitudinal stripe at middle of posterior margin.

Aedeagus ( Fig. 6A–D View Figure 6 ) elongate, about 3.0 times longer than wide (without flagellum); basal piece or phallobase ( Fig. 6B–D View Figure 6 ) elongate, about 1.6 times as long as parameres, moderately constricted in basal part, nearly straight in lateral view ( Fig. 6D View Figure 6 ), with pair of sclerotized dorsal plates; median lobe about 4/5 of length of paramere; penis slightly shorter and wider than paramere in ventral view; paramere without basal process, with slightly upturned apex; flagellum ( Fig. 6A View Figure 6 ) thick and very long, about 5.5 times as long as parameres.

Male paratypes ( Figs 1D–F View Figure 1 , 2B–D; n View Figure 2 =5). Measurements in millimetre (mm) with average value and standard deviation: BL, 31.7–34.8 (33.22±1.42); BLM, 27.3–29.9 (28.62±1.09); BW, 13.0– 14.2 (13.66±0.49); ML, 4.4–5.3 (4.82±0.37); HL, 3.4–4.5 (3.92±0.41); HW, 8.8–10.1 (9.72±0.55); PL, 7.4–7.9 (7.66±0.21); PW, 12.8–14.1 (13.46±0.53); EL, 17.1–18.1 (17.46±0.48); EW, 13.0–14.2 (13.74±0.49). Characters are mainly stable, except some differences in color and maculation of elytra ( Fig. 2 View Figure 2 ).

Female paratypes ( Figs 4 View Figure 4 , 7 View Figure 7 ; n =2). Body with mandibles (BL) 28.5–29.3 mm long, widest in middle of elytra. Measurements of other body parts in millimetre (mm): BLM, 26.1–27.3; BW, 12.9– 13.5; ML, 2.9–3.1; HL, 3.6–4.0; HW, 7.6–8.1; PL, 7.1–7.3; PW, 12.2–12.8; EL, 16.2–17.0; EW, 12.9– 13.5.

Body ( Fig. 4A–E View Figure 4 ) elongate-oval. Surface and color ( Fig. 4A, C–E View Figure 4 ) generally similar to those of males, but more deeply punctured on head and mandibles.

Head ( Fig. 4A–E, F View Figure 4 ) very small, strongly transverse, about twice as broad as long, widest across ocular canthi; pre-ocular margin with canthus well developed, rather strongly extending laterally, with broadly arcuate lateral margin, lacking posterior angle; forehead deeply densely punctured; vertex spherically swollen medially; surface irregularly punctate. Mandibles ( Fig. 4A, F View Figure 4 ) short, as long as head, inner edges flattened and sharp, each with four indistinct inner teeth. Mentum less haired than in male.

Pronotum ( Fig. 4A, D, E View Figure 4 ) rather strongly narrowed anteriorly, about 1.7–1.8 times wider than long, widest near basal 1/3, distinctly larger than head; each angle similar to that of male; posterior margin between posterolateral angles truncate.

Elytra ( Fig. 4A, C–E View Figure 4 ) rather long, elongate-oval, about 1.3 times longer than wide, broadest in middle, slightly wider than pronotum; humeri obtusely rounded; lateral margins narrowly explanate, broadly arcuate; surface evenly covered with fine punctures; color pattern similar to that of male.

Legs ( Fig. 4A–E, G View Figure 4 ) short, robust. Protibiae ( Fig. 4G View Figure 4 ) straight, thick, flattened, gradually distinctly widened apically; outer margin on anterior half to anterior 2/3 with 2–3 small blunt teeth accompanied by strongly bifurcate protibial apex (i.e., strongly pointed pair of teeth). Except apical spurs and spines, each mesotibia and metatibia without spine along outer edge.

Abdomen ( Fig. 4B View Figure 4 ) short, broad, strongly narrowed posteriorly. Ventrite V ( Fig. 4B View Figure 4 ) about 1.5 times as long as ventrite IV, with anterior margin broadly rounded. Tergite VIII ( Fig. 7A View Figure 7 ) semicircular, with membranous band along basal (anterior) margin, with broad membranous area at middle of anterior half. Sternite VIII ( Fig. 7B View Figure 7 ) strongly transverse, subdivided at middle; median portion hyaline, membranous. Hemisternites ( Fig. 7C, D View Figure 7 ) strongly sclerotized, posterior 2/3 plate-like whereas anterior 1/3 distinctly obliquely narrowed, with apical margin roundly angulate. Spermathecal duct ( Fig. 7C, E View Figure 7 ) darkened, joining in bursa copulatrix, distinctly expanded. Spermatheca ( Fig. 7C, E View Figure 7 ) darkened, situated at the apex of spermathecal duct, bulb–shaped symmetrically with expanded apex; spermathecal gland absent.

Etymology. This new species is named after the type locality “ Kon Tum ”.

Distribution. Central Vietnam (Dak Plo and Ngoc Linh in Kon Tum Province).

Bionomics. All specimens were collected in spring (March and April).

Remarks. Taxonomic studies on Neolucanus are generally difficult because of their slight differences in external and internal morphologies, especially in the male mandibles and genitalia, and the difficulty in obtaining several materials for one taxon ( Schenk 2014; Huang & Chen 2024). In this study, we successfully acquired a total of 8 specimens of both sexes for Neolucanus kontumensis sp. nov., allowing us to observe intraspecific variations. Considering the high proportion of endemism seen in Neolucanus , the new species may be narrowly distributed in a certain range in Kon Tum Province or its surrounding areas, although we believe it is necessary to await further distributional data on Neolucanus species in Vietnam.

Along with China, Vietnam is known for its diverse and rich fauna of Neolucanus ( Schenk 2014; Tsuchiya 2021). Indeed, some provisionally undescribed Vietnamese Neolucanus taxa have been reported ( Tsuchiya 2021). Therefore, it is not surprising to find an undescribed species of the genus from Vietnam, as in our case. Nevertheless, it is worth noting that such a conspicuous new species has just been discovered in the 2020s. More faunal surveys, particularly in unstudied areas, are required to reveal cryptic biodiversity in Central Vietnam, as represented by Maquart et al. (2023) for the Cambodian lucanids.