Didrepanephorus mucronatus Arrow, 1921

Qiu, Jian-Yue, Zhao, Ming-Zhi & Xu, Hao, 2021, Description of a new species of the genus Didrepanephorus Wood-Mason, 1878 (Coleoptera: Scarabaeidae: Rutelinae) from China with notes on allied species, Zootaxa 4933 (4), pp. 493-513 : 494-497

Didrepanephorus mucronatus Arrow, 1921 '腹镰'•龟

( Figs. 1–10 , 33–34 , 47–52 , 65–67 , 70 )

Didrepanephorus mucronatus Arrow, 1921: 379 (type locality: “ Laos ”), plate X, fig. 2 (habitus of holotype); Ohaus 1934b: 50; Paulian 1958: 78; Machatschke 1972: 8; Young 1999: 136, fig. 2 (lateral habitus of male); Muramoto & Fujioka 2000, figs. 7–9 (habitus and labels of holotype); Muramoto 2003: 30, figs. 4–6 (habitus, genitalia and labels of holotype); Krajčík 2007: 67; Krajčík 2012: 93.

Type material. Holotype (♂, by monotypy, BMNH, Figs. 47–52 ): Didrepanephorus mucronatus , Type, arrow // Indo-China., R. V. de Salvaza., 1920-47 // LAOS, m. yan. le 15-V-1919, R. Vitalis de Salvaza // Type, H. T.

Additional material examined (11♂♂, 8♀♀). CHINA: Yunnan: 1♂, 1♀ ( CZMZ) , 2014.V.15, Mengla County, Xishuangbanna , Chao-Tai WEI leg.; 1♂, 1♀ ( MYNU) , 2015.V, Jinghong, Xishuangbanna; 1♂ ( CLYJ) , 2017. IV.27, Dadugang, Jinghong, Xishuangbanna, Chao-Tai WEI leg.; 1♂ ( MYNU) , 2018.V.20, Dadugang, Jinghong, alt. 1,400 m, Jian-Yue QIU & Hao XU leg.; 2♂♂ ( MYNU) , 2018.IV.4, Mohan, Mengla County, Xishuangbanna, alt. 850 m, Yu-Tang WANG leg.; 1♂ ( MYNU) , same data but 2018.IV.7; 2♀♀ ( MYNU) , same data but 2018.IV.10, alt. 1,200 m; 2♀♀ ( MYNU) , same data but 2018.IV.24; 1♂ ( CCCC) , 1♀ ( MYNU) , 2018.IV.15, Mohan, Mengla County, Xishuangbanna, alt. 1,200 m, Yu-Tang WANG leg.; 1♂ ( MYNU) , 2018.V.31, Jinuoshan, Jinghong, alt. 1,100 m, Yu-Tang WANG leg.; 1♂ ( MYNU) , 2019.V.6, Jinuoshan, Jinghong, alt. 1,200 m, Yu-Tang WANG leg.; 1♀ ( MYNU) , 2019.V.7, Jinuoshan, Jinghong , alt. 1,200 m, Yu-Tang WANG leg .; LAOS: 1♂ ( CCZ), 2005.V.5–20, Phou Khao Khouay NBCA, Ban Van Hua env., Vientiane Municipal , 800– 1,000 m, M. Pejcha lgt .

Redescription (male). General: Body oval and convex, hairs and setae yellowish brown ( Figs. 1 , 5–8 ). Head: Dark brown. Clypeus flat, trapezoidal, anterior margin feebly arcuate, anterior angle almost right angle, sides strongly convergent anteriad and slightly swollen in basal half, roundly curved in middle, then almost subparallel in apical third; with irregular and moderately dense, small punctures, somewhat less punctured near anterior margin; surface with moderately dense minute setae, margins with erect short setae. Frontal-clypeal suture broadly interrupted medially, represented by a short carina at each side. Frons and vertex densely rugopunctate with dense, semierect long setae, the setae being rather long posteriad. Eye-canthus wide and truncate at outer margin, slightly extends beyond outermost point of eye, anterior angle broadly rounded. Antennomeres 2–7 dark brown, antennal club and antennomere 1 yellowish brown, length of antennal club distinctly longer than antennomeres 2–7 combined. Labrum exposed, anterior margin slightly raised at middle, dorsal surface rather sparsely microsculptured, with sparse, erect, short and long setae. Mandible dark brown, broadest at base, upper margin with an acute and distinct protrusion near base, strongly bended upward. Larger body size with longer mandibles ( Figs. 5–8 ). Maxillary palpi and labial palpi dark reddish brown, simple. Mentum and maxilla with dense punctures and long setae, anterior margin of mentum concave at middle. Gula dark brown, glabrous and matt. Pronotum: Yellowish-brown. Strongly convex, about 1.35 times as wide as long, widest near middle. Anterior margin distinctly bisinuate; anterior marginal membrane absent. Sides concave and not strongly convergent posteriad in basal half, roundly and broadly curved at middle, feebly concave and strongly convergent anteriad in apical half. Posterior margin broadly protruding in middle. Marginal lines completed, basal marginal line slightly vague at middle. Anterior and posterior angles both distinctly protruding and blunt at apices. Surface with rather dense small punctures, rugopunctate along lateral margin, disc with a longitudinal medial line. Most areas of surface with semierect, minute to short setae; setae on both sides of disc long and tufted. Scutellum: Dark brown. Nearly triangular to short triangular, lateral margin curved, apex rounded. Surface densely rugopunctate, with short setae on basomedial area. Elytra: Yellowish brown to brown. Convex, almost as wide as long, widest at middle. Surface with moderately dense, irregular, shallow, round to elliptical large punctures. Four innermost intervals recognizable but unclear, subsutural interstice widest. Surface with dense semierect setae; setae along base of elytra long and yellowish; on disc short and brownish; on distomarginal area and humeral umbone short, color gradually changed to dark brown; on distal declivity short, yellowish. Epipleura with dense minute setae. Ventral thoracic surface: Black. Anterior margin and lateral portions of ventral prothoracic surface with dense long hairs ( Fig. 2 ); ventral mesothoracic surface with sparse short setae; ventral metathoracic surface with rather dense long hairs. Prosternal process small, horizontally broad, shield-liked with an medial carina. Metasternum with a large, glabrous, longitudinal medial protrusion. Propygidium: Dark brown. Surface coarse, with rather dense, semierect short setae. Pygidium: Convex, apex concave. Dark brown. Surface coarse, with rather dense, semierect short setae. Abdomen: Reddish brown, with dense long hairs. Abdominal ventrites distinctly curved in lateral view; abdominal ventrites 1–4 strongly abbreviated; posterior margin of abdominal ventrite 6 broadly and deeply concave medially. Legs: Yellowish-brown. Femora with dense punctures and long hairs; tibiae with dense punctures and short setae; tarsi with dense, hard, short setae. Inner protarsal claw simple and thickened, outer protarsal claw smaller and sharp at apex. Outer meso- and metatarsal claws widely and deeply spilt into two branches respectively, the upper branches thinner and sharper, equal to the lower branches in length. Inner meso- and metatarsal claws more curved than the outer ones. Protibia with three distinct and acute teeth, the middle one is adjacent to the apical one. Protibial spur situates at the level of middle protibial tooth, vertically orient forwards. Meso- and metatibiae bidentate at apical edges, the upper tooth distinctly protruding. Protarsus strongly thickened; protarsomeres 2–4 abbreviated;protarsomere 4 ventrally with a short protrusion; meso- and metatarsomeres 4 each with an acute ventroapical protrusion, each protrusion with a pair of spines at base. Tarsomeres 5 of all legs with a ventral protrusion in basal third, which is distinct in protarsomere but indistinct in meso- and metatarsomere; protarsomere 5 with a distinct ventromedial protrusion. Aedeagus: As Figs. 33–34 .

Female: Body color darker; head, propygidium, pygidium and ventral surface black ( Figs. 3 , 9–10 ). Mandible small, nearly triangular; outer edge bidentate, both teeth acute and bend upwards. Clypeus longer than in male, anterior margin truncate and distinctly convex. Antennal club slightly shorter. Punctures on dorsal surface of head and pronotum denser and coarser; punctures on elytra denser. Setae and hairs on the whole body surface sparser and shorter. Elytra distinctly and broadly bulging at middle of lateral portion. Medial portion of metasternum flat. Abdominal ventrites evenly convex in lateral view; abdominal ventrites 1–4 almost equal; posterior margin of abdominal ventrite 6 straight medially ( Fig. 4 ). Protibia and mesotibia shorter and thinner; metatibia shorter but wider; protibial teeth acuter; tarsi of all legs shorter and thinner than in male; tarsomeres 4 of all legs each with an acute ventroapical protrusion, each protrusion with a pair of spines at base; tarsomeres 5 of all legs with a small and blunt ventral protrusion in basal third.

Measurements. Body length: male 18.3–22.4 mm, female 19.2–22.4 mm; body width: male 9.3–11.9 mm, female 10.0–12.4 mm.

Differential diagnosis. See remarks section.

Distribution. China: Yunnan (new record); Laos.

Natural history. This species inhabits the tropical rainforests at elevations of 850– 1,400 m around the border of China and Laos. Adults can be collected by light trap from early April to later May ( Figs. 65–67 ), but immature stages are unknown.

Remarks. Although Didrepanephorus mucronatus Arrow, 1921 has been mentioned several times ( Paulian 1958; Young 1999; Muramoto & Fujioka 2000; Muramoto 2003), no further specimens were reported since it was described. The new specimens collected in the past two decades from China do not only represent a new country record, but also allowed us to observe detailed morphological characters of this rare species and its variability. Didrepanephorus mucronatus , together with D. bifalcifer Wood-Mason, 1878 (Northeast India), D. arnaudi Muramoto, 2003 (South Vietnam), and D. vietnamicus Muramoto & Kobayashi, 2019 (Central and South Vietnam) can be subsumed in a species group ( D. bifalcifer group) based on the combination of the following morphological characters: lower margin of male mandible completed, without concavity before the basal tooth; upper margin of male mandible with a distinct denticle near base; pronotum of both sexes usually with tufted setae (except for D. vietnamicus ); abdominal ventrites with dense setae; phallobase strongly curved in profile.

Didrepanephorus vietnamicus is easily separated from the other three species by short, untufted pronotal setae and unicolor elytra ( Muramoto & Kobayashi 2019). While, D. mucronatus , D. bifalcifer and D. arnaudi possess distinct elongated dark patches on distomarginal area and apical umbone, which abruptly discard above distal declivity on elytra. Regarding males of the other three species of this group, D. mucronatus can be readily differentiated from D. bifalcifer by the mandibles curved in dorsal view ( Fig. 1 ; straight in D. bifalcifer , Fig. 41 ), the basal half of the side of pronotum distinctly concave ( Fig. 1 ; slightly concave in D. bifalcifer , Fig. 44 ), the disc of pronotum with two distinct tufted of dense setae ( Figs. 5–8 ; indistinct in D. bifalcifer , Fig. 44 ), and the shape of parameres (see Figs. 45, 51 ). The following features of D. arnaudi indicate its separation from D. mucronatus : the mandible more strongly curved in dorsal view, the basal half of the left paramere with an additional subtriangular extension, and the body color somewhat darker ( Muramoto 2003; Muramoto & Kobayashi 2019). The females of the three species are less informative and reliable separations are not available currently. The differential points as indicated by Muramoto (2003), viz. body color and shape of pronotum, are fairly variable when referring to the examined females of D. mucronatus .

Figures

FIGURE 70. Known distribution of four Didrepanephorus Wood-Mason, 1878 species. Type locality of D. mucronatus Arrow, 1921 is missing because the precise location is unknown.

FIGURES 1–4. Habitus of Didrepanephorus mucronatus Arrow, 1921 (dorsal and ventral view). 1–2, male; 3–4, female.

FIGURES 5–10. Habitus of Didrepanephorus mucronatus Arrow, 1921 (oblique view). 5–8, males in different body sizes; 9–10, females in different body sizes.

FIGURES 33–40. Male genitalia of Didrepanephorus Wood-Mason, 1878 species (showing parameres in dorsal and ventral views). 33–34, D. mucronatus Arrow, 1921; 35–36, D. heterocolor new species (holotype); 37–38, D. nishiyamai Muramoto, 2006; 39–40, D. subvittatus Benderitter, 1922.

FIGURES 41–56. Type specimens of Didrepanephorus Wood-Mason, 1878 species. 41–46, syntype, labels, and male genitalia of D. bifalcifer Wood-Mason, 1878 (male, BMNH, photograph by Chuan-Bu Gao); 47–52, holotype, labels, and male genitalia of D. mucronatus Arrow, 1921 (male, BMNH, photograph by Chuan-Bu Gao); 53–56, holotype and labels of D. subvittatus Benderitter, 1922 (female, IRSNB, photograph by Matthias Seidel).

FIGURES 65–69. Habitat of Didrepanephorus Wood-Mason, 1878 species. 65–67, habitat D. mucronatus Arrow, 1921: 65, forest in Mount Jinuoshan, Jinghong (Yunnan, China); 66–67, male attracted by light trap and stayed on a nearby bush in Dadu- gang (Yunnan, China); 68, male of D. nishiyamai Muramoto, 2006 on the ground (Guangxi, China; photograph by Chao Li); 69, male of D. subvittatus Benderitter, 1922 attracted by light trap and stayed on a nearby leaf in Mount Shiwandashan (Guangxi, China; photograph by Tao Zhang).