Neolucanus fuscus Didier, 1926

Neolucanus fuscus Didier, 1926 View in CoL

Suggested Chinese common name: Ḃ圆OiNJƤ

Figs. 1C–E View FIGURE 1 ; 2C–D View FIGURE 2 ; 3I–L View FIGURE 3 ; 4E–H; 5I–L View FIGURE 5 ; 6C, G, K; 7C; 8A–J

Neolucanus fuscus Didier, 1926: 210 View in CoL .

Neolucanus armatus View in CoL : Lacroix 1972: 111, fig. 1–3, type locality: Vietnam, Phố Hà Nội Province, Tam Dao; Nguyen 2013: 382 (synonymized with N. fuscus View in CoL ).

Neolucanus sianoukei View in CoL : Lacroix 1978: 270, fig. 1, type locality: Vietnam, Lâm Đồng Province, Ðà Lạt; Nguyen 2013: 382 (synonymized with N. fuscus View in CoL ).

Neolucanus zhongguo View in CoL : Schenk 2012: 3, fig. 1, type locality: China, Guangxi Province, Liuzhou City, Dayao Mountain .

Neolucanus fuscus zhongguo View in CoL : Schenk 2014: 35, fig. 42, new synonymy.

Type locality. Vietnam, Tuyên Quang Province .

Type material examined. None.

Additional material examined. China: 2 males ( CFYX), Guangxi Province, Guilin City , Ziyuan County, VI.2021, You Xiao leg. ; 2 males ( CFYX), Guangxi Province, Nanning City, Wuming County, Tianping , 3.VI.2023, local collector leg.; 1 male ( CZHQ), Guangxi Province, Daming Mountain , VI.2010, local collector leg.; 4 males ( CZHQ), Guangxi Province, Daming Mountain , 2–8.VII.2013, 1300m, Yanquan Lu leg. Vietnam: 8 males ( CXTZ), Yên Bái Province, 2023, local collector leg .; 18 males ( CZHQ), Yên Bái Province, Yên Bái City , VI.2024 , local collector leg.

Redescription of the male (n=35).

Body length: 29.2–57.1 mm ( Fujita 2010; Toshiyuki 2021; Yi 2023 and present paper)

Telodont. Habitus ( Fig. 1C–E View FIGURE 1 ). Head and pronotum black, elytra black or large areas yellowish; luster relatively matte; body with invisible pubescence in dorsal view, labium with dense setae, all legs with sparse yellow setae on surface.

Head transverse. Anterior ridge raised behind mandible and widely concave on the middle. Canthus long and wide, completely surround the eye. Clypeolabrum ( Fig. 3I View FIGURE 3 ) almost invisible in dorsal view, fused with frons. Mandible ( Fig. 3I–J View FIGURE 3 ) smooth from base to teeth on inner margin; in lateral view, clearly up-curved, a dorsal tooth behind apex forming an approximately acute-angle and significantly protrudes beyond upper margin, and protrudes to almost same length as lower tooth; in dorsal view, slightly curved, thickness almost regular from base to inner teeth, with 4–7 continuous small teeth behind apex and getting smaller apically. Antennal club with 3 antennomeres; antennomeres 8–9 subquadrilateral; antennomere 10 semi-elliptic.

Pronotum ( Fig. 3K View FIGURE 3 ) transverse, markedly longer and wider than head with slightly raised edges.Anterior margin bisinuate, posterior margin slightly bisinuate. Anterior angles relatively sharp and directed forwards, lateral angles and posterior angles obtuse.

Elytra elongate, anterior margin obviously narrower than pronotum.

Legs. Protibia ( Fig. 3L View FIGURE 3 ) with 2–3 conspicuous weakly sharp protuberances along outer margin, apex bifurcate with branches weakly sharp at tip, and base with a gap. Profemur ( Fig. 3L View FIGURE 3 ) with a semi-circular protrusion at apex. Mesotibia and metatibia straight and outer margin with a terminal spine, without external spines.

Abdomen and aedeagus. Abdominal tergite VIII ( Fig. 5I View FIGURE 5 ) nearly semilune, lateral angles poorly defined. Abdominal ventrite VIII ( Fig. 5J View FIGURE 5 ) with 2 obvious protruding tips on basal margin near middle. Ventral plate of abdominal segment IX ( Fig. 5L View FIGURE 5 ) wide without membranous stripe, an ambiguous protrusion on both side near base, basal 2/3 almost equally wide, then widens towards apex, and gradually constricted near apex. Aedeagus ( Fig. 6C, G, K View FIGURE 6 ) with a large triangular pair of sclerotized dorsal plates and almost intersecting; ventral plate at apical end of basal piece with a sclerotized protruded part. Paramere wide, with relatively large inner curvature at base, apex of paramere curved outward. Penis about 0.65 times length of paramere in ventral view. Flagellum long, apex of flagellum simple.

Variation. Mesodont. Mandible only weakly longer than head, with a bifurcated sharp large tooth at base and continuous small teeth, the largest one at about proximal 1/3. Amphiodont and priodont ( Figs. 2C–D View FIGURE 2 ; 8A–B View FIGURE 8 ). Mandible weakly shorter than head with unclear consecutive small teeth on inner side, without branch at apex in lateral view; clypeolabrum ( Figs. 4E View FIGURE 4 ; 8A View FIGURE 8 ) clearly visible in dorsal view.

Differential diagnosis. See Table 1 View TABLE 1 and 2 View TABLE 2 .

Distribution. China (Guizhou, Guangxi, Yunnan); Vietnam (Lào Cai, Thái Nguyên, Tuyên Quang, Yên Bái) ( Fujita 2010; Schenk 2012, 2014; Toshiyuki 2021; Yi 2023 and present paper).

Remarks. A notable feature observed is a gap at the base of the protibia, which can be folded to fit snugly into a semi-circular protrusion located at the apex of the profemur.

In our examination of telodont males of N. fuscus from northern Vietnam and southern China, we found no discernible differences between the two populations in terms of external features or male genitalia. Furthermore, we inspected an ampriodont male ( Fig. 8A–J View FIGURE 8 ) from Nanning, Guangxi Province, China, which exhibited no external distinctions from the holotype of N. fuscus zhongguo (see fig. 1 in Schenk 2012). Besides, the distance and geographical conditions of the interconnected distribution areas do not present any significant isolation that would justify the differentiation of N. fuscus into subspecies. Therefore, we propose that N. fuscus zhongguo should be considered a new junior synonym of the nominate subspecies.