Anelosimus dude Agnarsson, n. sp.

Anelosimus dude Agnarsson n. sp.

(Figs 5D–F, 8A–F, 9A–G, 18E)

Additional material examined

10 ♂, 15Ψ: Same data as holotype. 20 ♂, 60 Ψ: Same data as holotype, except 1370 m. 2 ♂: Tanzania, Tanga, Lushoto District, Mazumbai Forest Reserve, 4º49’S 38º29’E, 1650–1730 m, 18.ix.1995.

Etymology

The species epithet is a noun in apposition, after “The Dude ” a character in the movie “The Big Lebowski” by Joel and Ethan Coen.

Diagnosis

Anelosimus dude males can be distinguished from all other Anelosimus, except A. kohi and A. monskenyensis by the simple and short embolus and unmodified embolus base, and from A. kohi and A. monskenyensis by the voluminous tegulum (Figs 5D, 8C–F). Females are readily separated from other Anelosimus, except A. biglebowski by the large size of the spermathecae relative to the epigynal plate. Females differ from A. biglebowski in that the epigynum is usually very lightly sclerotized so that spermathecae are seen very clearly through the cuticle (Fig. 18E), the genital opening is wide in relation to spermathecae, and copulatory ducts are shorter (Figs 5E–F).

Description

Male (holotype): Total length 1.85. Prosoma 0.90 long, 0.70 wide, brown, cephalic area and a narrow rim around the edge slightly darker. Sternum 0.55 long, 0.45 wide, light brown with a narrow darker rim. Opisthosoma 1.00 long, 0.90 wide, with Anelosimus pattern, dull gray with a dorsal longitudinal notched fovea, bordered by bands of white. Colular setae are smaller than in most other Anelosimus and may be difficult to see under a dissecting microscope. Eyes subequal about 0.07 diameter. Clypeus height about 2.4 times AME diameter. Leg I femur 1.30, patella 0.25, tibia 0.95, metatarsus 0.70, tarsus 0.45. Legs pale yellow with distal half of femur I slightly darker. Femur I about 5 times longer than wide. 2–5 trichobothria dorsally on all tibia, 2–4 on tibia I–III, 4–5 on tibia IV. 2 prolateral and 1 retrolateral trichobothria on palpal tibia. Stridulatory pick row on opisthosoma nearly straight, consisting of approximately seven to eight modified setal bases (Fig. 9E). Epiandrous gland spigots in two clearly separate groups of 6–7 fusules (Fig. 9B).

Palpal organ as in Figures 5D, 8A–F.

Female (paratype): Total length 2.10. Prosoma 0.95 long, 0.70 wide, brown, cephalic area and a narrow rim slightly darker. Sternum 0.60 long, 0.50 wide, brown, slightly darker than male, with a narrow darker rim. Opisthosoma 1.25 long, 1.10 wide, pattern as in male. Colular setae are smaller than in most other Anelosimus and may be difficult to see under a dissecting microscope. Eyes subequal about 0.07 diameter. Clypeus height about 2.3 times AME diameter. Leg I femur 1.15, patella 0.30, tibia 0.95, metatarsus 0.85, tarsus 0.50. Legs brownish yellow with distal half of femur I darker and distal tip of femur IV and tibia I and IV also slightly darker. 2–5 trichobothria dorsally on all tibia, 2–4 on tibia I–III, 4–5 on tibia IV. 2 prolateral and 1 retrolateral trichobothria on palpal tibia. Epigynum as in Figures 5E–F, 9A.

Va r i a t i o n

Variation in coloration (in alcohol) of opisthosoma of both sexes is large and ranges from grayish with a dull folium to dark gray with a folium bordered with sharp white. The light gray coloration is more common. Leg coloration ranges from yellow to brownish. Male total length from 1.80–2.10, femur I from 1.15–1.40, female total length from 1.85–2.15, femur I from 0.95–1.20.

Distribution

Only known from two localities in Tanzania, the Uzungwa Scarp Forest Reserve (type locality) and the Mazumbai Forest Reserve.

Natural history

Most specimens were collected by canopy fogging but a few by sweeping vegetation. Habitat was mid elevation rainforest (1370–1730 m). The species was most common in samples from 1370 m, abundant in samples from 1515 m, but very rare in samples from 1650–1730 m. The sex ratio of collected specimens of about 2.6 females per male, while weak evidence, does not suggest that these animals are permanently social, while the phylogenetic position predicts subsociality.

Phylogenetics

Anelosimus dude has been included in several phylogenetic analyses, as Anelosimus sp. 2 (Agnarsson 2003, 2004) and Anelosimus sp. 3 Tanzania (Agnarsson 2005, 2006). For the phylogenetic position see under A. biglebowski.