Anelosimus kohi Yoshida, 1993

Agnarsson, Ingi & Zhang, Jun-Xia, 2006, New species of Anelosimus (Araneae: Theridiidae) from Africa and Southeast Asia, with notes on sociality and color polymorphism, Zootaxa 1147, pp. 1-34 : 21-25

Anelosimus kohi Yoshida, 1993

( Figs 2 A–E, 3 A–I, 11 A–H, 12 A–F, 13 A–G)

Anelosimus kohi Yoshida, 1993: 8 , figs 1–3.

Types

Male holotype ( NSMT –Ar 2966) and a paratype (1 Ψ, NSMT –Ar 2967) from Singapore, deposited in the collection of the Department of Zoology, National Science Museum, Tokyo, examined.

Additional material examined

7 ♂, 25 Ψ: Singapore, Palau Ubin, Chek Jawa, 1 ° 24 ’ 25.2 ”N, 103 ° 59 ’ 27.6 "E, altitude 0–5 m, 30.iv. 2005, W. Maddison, D. Li, I. Agnarsson, J. X. Zhang, ( NMNH). 5 ♂, 20 Ψ: Malaysia, Johor, Teluk Mahkota, 1 ° 54 ’0”N, 104 ° 6 ’ 14.4 ”E, altitude 0–5 m, 25–26.v. 2005, W. Maddison, D. Li, I. Agnarsson, J. X. Zhang, ( NMNH).

Diagnosis

This species differs from all other Anelosimus in lacking colular setae. Anelosimus kohi males differ from those of all other Anelosimus species by the simple, short embolus, lacking an elaborate ’embolic division b’ ( Agnarsson 2006). Females differ from all other Anelosimus by having two pairs of spermathecae (or a pair of accessory sacs, in addition to the spermathecae), see Figures 11 E–F, G–H.

Description

Male ( Singapore, Palau Ubin, Chek Jawa, N 1.407 °, E 103.991 °, 30.iv. 2005, W. Maddison, D. Li, I. Agnarsson, J.X. Zhang): Total length 2.50. Prosoma 1.30 long, 1.30 wide, light or dark brown, center darkest. Sternum 1.00 long, 0.80 wide, pale yellowish. Opisthosoma 1.65 long, 1.30 wide. Pattern as in Figures 3 C–D. Eyes subequal in size about 0.10 in diameter. Clypeus height about 1.8 times AME diameter. Leg I femur 1.80, patella 0.65, tibia 1.70, metatarsus 1.70, tarsus 0.70. Femur I about 4 times longer than wide. Leg formula 1243. Leg pale to dark brown, femora and distal tip of tibia darker. 3–5 small trichobothria dorsally on all tibia, 3–4 on tibia I–III, 5 on tibia IV. 2 prolateral and 1 retrolateral trichobothria on palpal tibia. Stridulatory pick row on opisthosoma distinctly curved, with distal setae compressed, consisting of approximately 16–19 modified setal bases ( Fig. 13 F). Epiandrous gland spigots in two separate groups with approximately 8–9 fusules, but less tightly arranged than in many other Anelosimus ( Fig. 13 B).

Palpal organ as in Figures 11 A–D, 12 A–F.

Female (data as male): Total length 3.80. Prosoma 1.80 long, 1.45 wide, light or dark brown, center darkest. Sternum 1.10 long, 0.95 wide, pale yellowish. Opisthosoma 2.30 long, 1.75 wide. Pattern as in Figures 3 A–B, E–I. Eyes subequal in size about 0.10 in diameter. Clypeus height about 2.1 times AME diameter. Leg I femur 2.40, patella 0.80, tibia 2.10, metatarsus 2.10, tarsus 0.80. Femur I about 5 times longer than wide. Leg formula 1423. Leg pale to dark brown, femora and distal tip of tibia darker. 3–5 small trichobothria dorsally on all tibia, 3–4 on tibia I–II, 4–5 on tibia III–IV. 3 dorsal trichobothria on palpal tibia.

Epigynum as in Figures 11 E–H, 13 A.

Va r i a t i o n

The color variation is striking in this species, mostly representing two rather distinct color morphs, uniformly reddish brown with dark brown dorsal folium on the opisthosoma ( Figs 3 A–C), or a morph with contrasting colors, a gray opisthosoma, and red dorsal folium bordered by a broad, bright yellow band ( Figs 3 D–H). Some lightly colored, less contrasty forms also exist ( Fig. 3 I). Male total length from 2.40–3.40, femur I from 1.70–2.40. Female total length varies from 3.70–4.40 and femur I from 2.30–2.80. The genitalia of both sexes are quite variable also ( Figs 11 A–H, 12 A–F, 13 A). The shape of the embolus base, and the length of the embolus tip differ considerably between specimens. The length versus the width of the palpal organ varies with some palps appearing rather long and narrow, others short and stubby. The epigyna also vary in the shape of the epigynal bursa, and of the spermathecae. None of these morphological variations seem to correlate clearly with the color morphs, or localities.

Distribution

Only known from Singapore and Malaysia.

Natural history

Anelosimus kohi builds Anelosimus ‘basket webs’ (see Agnarsson 2006), which were encountered at the tips of branches of trees along the beach in Singapore and Malaysia. Based on observing a number of webs and examining their content, Anelosimus kohi appears to be a subsocial species, similar to Anelosimus arizona (e.g. Avilés & Gelsey 1998), with webs founded by single females, and colonies consisting of a female and her offspring persisting until the spiderlings disperse close to adulthood.

Taxonomic note

Considering the extensive variation in habitus color and genitalia morphology it is certainly possible that what we here circumscribe as one, may represent two, or even more species. However, we prefer the current taxonomical hypothesis because genitalia morphology seems to vary continuously, and genital variation does not seem to correlate with coloration, or geographic locality. Furthermore, preliminary molecular data (Agnarsson unpublished) indicates that ‘contrasty’ vs. ‘uniform’ color morphs are not distinct (or respectively monophyletic). The current taxonomical hypothesis makes testable predictions about the expected gene flow and ease of breeding between ‘morphs’ and the hypothesis that all these morphs represents a single species could be rejected by e.g. demonstrating inability of morphs to interbreed.

Phylogenetics

Anelosimus kohi was included in the phylogenetic analyses of Agnarsson (2005, 2006) as “A. sp. 4 Singapore ”. In those analyses A. kohi was sister to a large clade (termed the E b clade for a conspicuous synapomorphy, the ‘embolic division b’, see Agnarsson 2006) of European, African and American species including the ‘filiform embolus clade’ (see Fig. 1) and the Madagascar group plus the eximius lineage. Preliminary molecular data suggests a similar placement (Agnarsson unpublished).