Anelosimus membranaceus, Zhang, Bao-Shi, Liu, Long & Zhang, Feng, 2011

Zhang, Bao-Shi, Liu, Long & Zhang, Feng, 2011, The cobweb spiders of the genus Anelosimus Simon, 1891 (Araneae: Theridiidae) in Hainan Island, China, Zootaxa 2833, pp. 49-59 : 50-52

Anelosimus membranaceus new species

( Figs 1 – 6 )

Type material. Male holotype, from Jianfengling Mountain (19°07ʹN, 109°13ʹE), Hainan Island, 29 May 2009, C. Zhang leg. Paratypes: Hainan Island: 1 male and 2 females, same data as holotype; Bawangling Mountain (19°07ʹN, 109°04ʹE): 1 male and 1 female, 31 July 2007, F. Zhang leg.; 1 male, 8 November 2008, G. X. Han leg.; 1 female, 21 May 2009, C. Zhang leg.; 1 male, 25 May 2009, C. Zhang leg.; 1 female, Diaoluo Mountain (18°45ʹN, 109°45ʹE), 5 June 2009, C. Zhang leg.

Diagnosis. Males can be distinguished from other Anelosimus species by the short, spiraling embolus. This new species is similar to A. exiguus Yoshida, 1986 , A. taiwanicus Yoshida, 1986 and A. dude Agnarsson, 2006 in having a similar palpal organ, but can be distinguished by the shape of embolic base and the embolic origination ( Figs 3–4 ). Females can be distinguished from all other Anelosimus species except A. linda Agnarsson, 2006 and A. seximaculatum ( Zhu, 1998) by the short, straight copulatory ducts. It differs from A. linda by the shape of copulatory openings, and from A. seximaculatum by having two copulatory openings ( Figs 5–6 ).

Etymology. The species name refers to the membranous apophysis of the embolus.

Description. Male holotype, total length 1.85: prosoma 0.80 long, 0.72 wide; opisthosoma 1.08 long, 0.82 wide.

Color. Carapace ( Fig. 1 ) yellow brown. Cervical groove, radial furrows and median furrow gray black, anterior median part between cervical grooves gray black, with a thin black striate posterior to PME. Eyes with black ring. Chelicerae and sternum yellowish. Endites brown, white distally. Labium brown. Legs yellowish, reddish-brown on femora I. Dorsum of opisthosoma gray yellow, with ripple-shaped lateral striates, covered with small white patches, with dispersive white patches medially; venter gray. Spinnerets gray black.

Prosoma ( Fig. 1 ). Carapace longer than wide, with several black setae anteriorly. Both the eye rows recurved from dorsal view. Eye measurements: AME 0.08, ALE 0.08, PME 0.09, PLE 0.08; AME–AME 0.07, AME–ALE 0.02, ALE–ALE 0.42, PME–PME 0.05, PME–PLE 0.07, PLE–PLE 0.43, ALE and PLE contiguous. MOA long 0.25, front width 0.23, back width 0.22. Clypeus height 0.14 and covered with few setae. Promargin of chelicerae with three teeth, with the third one largest; retromargin with four small teeth. Anterior margin of endites armed with gray scopula. Labium 0.14 long, 0.18 wide, armed with sparse black setae. Sternum 0.54 long, 0.50 wide and covered with sparse black setae, with anterior lightly procurved margin.

Legs. Thin except femora I sturdy. Measurements of legs: leg I 3.65 (1.17, 0.27, 0.99, 0.81, 0.41), II 2.62 (0.90, 0.23, 0.54, 0.54, 0.41), III 1.86 (0.54, 0.14, 0.45, 0.36, 0.32), IV 2.17 (0.63, 0.23, 0.45, 0.54, 0.32). Leg formula: 1243.

Opisthosoma ( Fig. 1 ). Oval, longer than wide, covered with brown setae.

Male palp ( Figs 3–4 ). Embolus flagelliform, coiled and originating from the ventral genital bulb, furnished with a membranous apophysis near distal tip; conductor small, membranous, and concealed under embolus; median apophysis semicircular. The width of tibia equal to its length.

Female (paratype from Jianfengling Mountain), total length 1.94: prosoma 0.81 long, 0.77 wide; opisthosoma 1.08 long, 0.95 wide.

Color. Cervical groove and median furrow gray black, anterior median part between cervical grooves light black, with a black striate extending from posterior PME to median furrow. Other characters as in holotype.

Prosoma. AER recurved and PER procurved from dorsal view. Eye measurements: AME 0.09, ALE 0.09, PME 0.10, PLE 0.09; AME–AME 0.07, AME–ALE 0.03, ALE–ALE 0.40, PME–PME 0.07, PME–PLE 0.07, PLE–PLE 0.42, ALE and PLE contiguous. MOA long 0.22, front width 0.22, back width 0.22. Clypeus height 0.10. Labium 0.14 long, 0.25 wide. Sternum 0.66 long, 0.57 wide. Promargin of chelicerae with three teeth, retromargin with five small teeth.

Legs. Femora I lightly sturdy. Measurements of legs: leg I 3.27 (1.13, 0.32, 0.69, 0.77, 0.36), II 2.67 (0.86, 0.27, 0.59, 0.59, 0.36), III 1.81 (0.68, 0.18, 0.32, 0.36, 0.27), IV 2.75 (0.81, 0.27, 0.63, 0.63, 0.41). Leg formula: 1423.

Female genitalia ( Figs 5–6 ). Epigynum lightly sclerotized, posterior atrium wider than long, anterior atrial margin recurved; spermathecae oval; copulatory ducts short, connected with spermathecae posteriorly.

Variation. Dorsal opisthosoma of holotype with inconspicuous median stripe, but some specimens have darker median stripe, particularly anteriorly and posteriorly ( Fig. 2 ). Male total body length varies from 1.85–1.98 and female from 1.82–1.94.

Distribution. China (Hainan).

Comments. This species probably belongs to the “filiform embolus” Anelosimus clade of Agnarsson (2006) and Agnarsson & Zhang (2006), with a characteristically large tegulum and filiform embolus.

Figures

FIGURES 1 – 6. Anelosimus membranaceus n. sp. 1, 3 – 4, male holotype. 1, body, dorsal view; 2, opisthosoma of other male, dorsal view; 3, male left palp, ventral view; 4, same, prolateral view; 5 – 6, female paratype. 5, epigynum, ventral view; 6, vulva, dorsal view. Scale bars: 1 – 2, 0.5 mm; 3 – 6, 0.1 mm.