Hybovalgus bioculatus Kolbe, 1904

Ricchiardi, Enrico, 2017, Revision of Chinese mainland Hybovalgus Kolbe, 1904, with description of a new species, and Excisivalgus Endrödi, 1952 reduced to synonymy with Hybovalgus (Coleoptera: Scarabaeidae), European Journal of Taxonomy 340 (340), pp. 1-32 : 11-13

Hybovalgus bioculatus Kolbe, 1904

Fig. 5

Hybovalgus bioculatus Kolbe, 1904: 56 .

Hybovalgus bioculatus – Schenkling 1922: 51. — Ma 1995: 196, fig. 168, misidentification, it is Hybovalgus thibetanus .

Material examined

VIETNAM: 7 ♂♂ ( MNHUB), 1 ♂, 1 ♀ ( ERC), Montes Mauson, 2000–3000’, Apr.– May, H. Fruhstorfer leg. (same locality and data of type series but these specimens are not labelled as such); 1 ♂, Vinh Phuc Prov., Tamdao, Tam Dao N.P. , about 21°29′01″ N, 103°36′41″ E, May 1997 ( ERC); 1 ♂, Ht. Tonkin, Lao Kay, Lào Cai, 22°20′14″ N, 104°08′54″ E, Bourgoin Coll. B.M. 1938-252 ( NHM); 2 ♂♂, Chapa, Sa Pa , 22°19′23″ N, 103°52′22″ E, May–Jul. 1918, Bourgoin Coll. B.M. 1938-252 ( NHM); 2 ♂♂, Tonkin, Chapa, 1 Jun. 1916, R.Vitalis de Salvaza leg., Bourgoin Coll. B.M. 1938-252 ( NHM).

LAOS: 3 ♂♂, 1 ♀, Huaphan Prov, Ban Saleui , Phou Pan Mt. , about 20°12′ N, 104°01′ E, 1300–1900⁄m, 11 Apr.–15 May 2012, C.C. Holzschuh leg. ( ZFMK); 1 ♂, Huaphan Prov., Mt. Phu Phan , 2060 m, Apr.– May 2012, local collectors ( ERC).

CHINA: 3 ♂♂, Hainan, Wuzhishan , about 18°46′29″ N, 109°30′60″ E, 1 Jun. 2009 ( ERC); 2 ♂♂, Guangxi, Mt. Dayaoshan, 24°08′11″ N, 110°11′19″ E, Linxiang , Jinxiu , 700 m, 25 Apr.–5 May 2014, Huang Yuanyong and Li Dong leg. ( ERC); 1 ♂, Guangxi, Mt. Dayaoshan, Pingzhao , Jinxiu , 1200 m, 15–25 May 2014, Zhao Jinsheng leg. ( ERC).

Remarks

Kolbe (1904: 57) wrote that the locality where Fruhstorfer collected the type series was at 2–3000 m, but this is incorrect, as the original labels bears the mention “ 2-3000’ ” (’ = feet). In fact, the highest point of Montes Mauson is actually 1541 m (5249’). Many, or all of the specimens of H. bioculatus preserved at MNHUB and ERC most probably belong to the H. bioculatus type series, but they were not labelled as such by Kolbe who wrote “Eine Anzahl Exemplare”. Scanning the literature dealing with H. bioculatus , we concluded that the female of this species was never described and probably Kolbe himself failed to pair the two sexes. This is clear because one of the specimens (ERC) is a female (described below), and Kolbe wrote on one small label “keine Forceps” without recognizing it as female.

Description of a female from Montes Mauson (ERC; type locality of the species)

MEASUREMENTS. Length 8.0 mm; width 5.1 mm. Body colour mostly castaneous.

HEAD. Black, slightly shiny, covered with large, round punctures each with a bristle-like, erect, testaceous scale. Clypeus black, with anterior margin castaneous, anterior margin sinuate, suctorial brush shorter than that of male.

PRONOTUM. Black, nearly glabrous, trapezoidal, slightly crenate at sides, laterally depressed at center of lateral margins; anterior angle acute, posterior angle obtuse, apical margin rounded with a small ridge inclined at approximately 45°; posterior margin with central part deeply excavated as an enlarged “E” ( Fig. 5F ); carinae rounded, parallel, ending around middle of disk; central small carina not present; lateral carinae obsolete; with 2 testaceous, barely noticeable, central carina scale tufts; with 2 more or less noticeable, small, scales tufts at posterior angle.

SCUTELLUM. Black, long, apically rounded, nearly glabrous.

ELYTRA. Castaneous, slightly shiny, mostly glabrous, with shallow, black juxtascutellar depression, the anterior half of which is surrounded by a prominent ridge; humeral humbones prominent, with a small, testaceous scale tuft; anteapical umbones slightly prominent, with a prominent testaceous scale tuft directed posteriorly. Part of disk black, with thick, small, recumbent, barely noticeable scales.

PROPYGIDIUM. Castaneous, slightly shiny, nearly glabrous, with scattered, small, recumbent black scales; posterior margin curved inward at middle, with 2 prominent, black propygidial scale tufts. Cones at posterior margin short and blunt.

PYGIDIUM. Black, wider than long, slightly shiny, nearly glabrous, covered with scattered, small, recumbent, black scales; narrowing to apex, where there is a prominent rounded projection, showy in lateral view. Ventrally with a hollowed surface, glabrous and posteriourly semicircular. Apex with a prominent, testaceous scale tuft.

PROTIBIA. Black, with 5 external teeth: 1–3 long, 4–5 smaller, all rounded at apex. Teeth 4–5 closer to one another than to 1–3.

MESO- AND METAFEMUR. Castaneous with a small, testaceous scale tuft at centre of posterior margin.

METATIBIA. Castaneous, centrally enlarged, without a tooth at center of posterior margin. First metatarsomere long, twice length of second.

ABDOMEN. Castaneous, covered with thick, recumbent, testaceous scales. Anal sternites longer than other visible sternites, with same scales but centrally glabrous.

Species variability

Males

Length 7.7–8.5 mm; width 4.5–5.1 mm. The colour of the body is stable. Along posterior border of pygidium, in the places where Valgina often have scale tufts, H. bioculatus sometimes shows a glabrous surface, while in other specimens there are small, thick, erect scales whose colour varies from testaceous, to dirty testaceous to blackish. Lastly, in Chinese specimens the two posterior margin propygidial scale tufts and humeral humbone scale tufts are dirty testaceous instead of testaceous. Two of the three specimens from Guangxi have the basomedial notches of the parameres closed.

Females

The only two known females do not show any significant variation.

Flight period

The adults of this species were collected from mid-April to early June at an elevation of 700–1900 m.

Distribution

Hybovalgus bioculatus was described from northern Vietnam. New records reported here came from northern Laos and China (Hainan, Guangxi).

Figures

Fig. 5. Hybovalgus bioculatus Kolbe, 1904 (ERC). A–E. ♂. A. Habitus, dorsal view. B. Propygidium and pygidium. C–E. Aedeagus (grey: parameres; white: phallobase). C. Dorsal view. D. Lateral view. E. Posterior view. F–G. ♀. F. Habitus, dorsal view. G. Propygidium and pygidium.