The theridiosomatid genus Baalzebub was erected by Coddington(1986)to accommodate the type species, B. baubo Coddington, 1986 and other two, Theridiosoma albonotatum Petrunkevitch, 1930 and T. brauni Wunderlich, 1976. At present, 6 species were included in this genus(World Spider Catalog, 2015), while their distribution is very wide and still “circumtropical”, as summarized by Coddington(1986). The type species and B. albonotatus were from Latin America(Coddington, 1986), B. brauni from Queensl and of Australia(Davies, 1988) and the other three species, B. nemesis Miller, Griswold & Yin, 2009, B. rastrarius Zhao & Li, 2012 and B. youyiensis Zhao & Li, 2012, were from the subtropical area of China: Yunnan, Guizhou and Guangxi etc. (Miller et al., 2009; Zhao & Li, 2012). The genus Baalzebub can be distinguished by elongate tegulum, a small, triangular median apophysis, a long, sharp paracymbium, and complicated branching embolus covered by broad conductor, and by the spermathecae connected with each other, broad epigynal plate with a central sclerotized pit, and forming a backward-pointed scape.

The species, B. youyiensis Zhao & Li, 2012 was originally described based on four female specimens collected from a cave of Guangxi. When we checked the theridiosomatid materials from Laos, a Baalzebub species containing 3 male and 17 female specimens caught our attention. The females were B. youyiensis. The male specimens have habitus and marking similar to the females, and the palpal structures show the characters of Baalzebub (Coddington, 1986; Davies, 1988; Zhao & Li, 2012). Therefore, we considered both males and females conspecific, and the males of B. youyiensis were described for the first time.

All measurements are given in mm. Specimens are preserved in 95% alcohol and were examined and measured under a Leica M205C stereomicroscope, and photographed with a Canon EOS 60D digital camera(18.0 megapixels)mounted on an Olympus BX43 compound microscope. The images were mounted using Helicon Focus 3.10.3 software(Khmelik et al., 2006). Map was created using Arcview 3.3. Specimens are deposited in the Museum of Sichuan University(SCUM)in Chengdu.

Baalzebub youyiensis Zhao & Li, 2012 (Figs 1~17)

Baalzebub youyiensis Zhao & Li, 2012: 17, figs 9A~E, 10 A~B(female).

Material examined: 4 females(holotype and paratypes, IZCAS): China, Guangxi: Pingxiang county-level city, Youyi town, Bantou village, Niuyan cave, 22°05.666′ N, 106°45.439′ E, elevation ca 251 m, 18 January 2011, Z.G. Chen & Z.W. Zha leg.; 3 males and 17 females(SCUM): Laos, Bolikhamsai: Lak Sao, Transiten, in Lang cave, 18°23.318′ N, 104°32.675′E, elevation ca 318 m, August 2012, P. Jäger. leg.

Diagnosis: Male of this species is similar to B. albonotatus(see Coddington, 1986: 74, fig. 164) and B. brauni(see Davies, 1988: 326, fig. 43)in having a cluster of setae of cymbium and a long and pointed paracymbium, but can be distinguished from other Baalzebub species by the presence of a broad lateral lobe(Fig. 14), the slender median apophysis(Figs 7, 11), the securiform conductor(Fig. 13) and the multiramose embolus(Figs 7, 10~12). Female distinguished by the semi-transparent epigynal scape with a blunt tip, which is proportionately shorter(Fig. 16). Spermathecae contrasted with short, long spermathecae in other Baalzebub species(Fig. 17). The relatively shorter, smaller spermathecae surrounding by copulatory ducts made up of ovoid loops(Fig. 17).

Description: Habitus as in Figs 1~6. Dorsal shield of prosoma broad, nearly pear-shaped, orange. Cephalic area slightly evelated. Eyes with black base. Anterior eye row procurved, posterior eye row recurved. Cervical groove distinct, thoracic fovea unconspicuous. Sternum heart-shaped. Legs yellow, brown from patella to tarsus(except leg Ⅰ). Opisthosoma sub-elliptic in dorsal view, rugose in laterals, pale yellow in male, glum yellow in female, with darkish pigmentation patches in laterals and venter.

Male palp(Figs 7~14): Patella with a strong macroseta(Fig. 7). Tibia with three trichobothria and macrosetae(Figs 9, 14). Paracymbium L-shaped, with a long, sharp, distal end(Figs 8, 14). Lateral lobe broad, semi-transparent(Fig. 14). Tegulum large, surface with delicate texture(Figs 8~10). Median apophysis relatively small, sub-triangular, with a sharp corner(Figs 7, 11). Conductor securiform, translucent, with distinct texture and grains(Fig. 13). Embolic end multiramose, with a broad affiliated lobe(Fig. 12).

Female copulatory organ(Figs 15~17): see Zhao & Li(2012).

Male: Total length 1.52, carapace 0.86 long, 0.88 wide, clypeus 0.18 high, sternum 0.41 long, 0.45 wide, coxae Ⅳ separated by 1.00 time their width. Posterior median eyes separated by less than half of their diameter. Macrosetae: Leg Ⅰ: femur r 1, patella d 1, tibia p 2, r 3; Leg Ⅱ: patella d 1, tibia r 1, metatarsus p 1; Leg Ⅲ: tibia d 1; Leg Ⅳ: patella d 1, tibia d 2. Metatarsal trichobothria: Tm Ⅰ: 0.15; Tm Ⅱ: 0.29; Tm Ⅲ: 0.17; Tm Ⅳ: 0.30. Leg measurements: Ⅰ 3.61(1.05, 0.42, 0.98, 0.73, 0.43); Ⅱ 2.96(0.88, 0.38, 0.72, 0.59, 0.39); Ⅲ 2.13(0.63, 0.30, 0.42, 0.42, 0.36); Ⅳ 2.45(0.81, 0.29, 0.51, 0.53, 0.31).

Female: Total length 1.95, carapace 1.08 long, 0.99 wide, clypeus 0.18 high, sternum 0.49 long, 0.51 wide, coxae Ⅳ separated by 1.00 time their width. Posterior median eyes separated by less than half of their diameter. Macrosetae: Leg Ⅰ: patella d 1, tibia d 1, r 1; Leg Ⅱ: patella d 1, tibia d 2, r 1; Leg Ⅲ: patella d 1, tibia r 1; Leg Ⅳ: patella d 1, p 1; tibia d 1. Metatarsal trichobothria: Tm Ⅰ: 0.22; Tm Ⅱ: 0.33; Tm Ⅲ: 0.33; Tm Ⅳ: 0.32. Leg measurements: Ⅰ 3.95(1.29, 0.47, 0.96, 0.79, 0.44); Ⅱ 3.40(1.11, 0.42, 0.78, 0.67, 0.42); Ⅲ 2.32(0.71, 0.34, 0.48, 0.48, 0.31); Ⅳ 2.73(0.88, 0.33, 0.62, 0.59, 0.31).

Distribution: south China(Guangxi), Laos(Fig. 18).

Acknowledgements: Thanks to Dr. Peter Jäger(Senckenberg Research Institute, Senckenberganlage, Frankfurt am Main, Germany)for providing valuable specimen materials. We are grateful to anonymous referees for their comments on the manuscript.