Bioacoustics of Anelosimus biglebowski

Description Male ( holotype ): Total length 1.90. Prosoma 0.95 long, 0.80 wide, brown, cephalic area and a narrow rim around the edge of prosoma slightly darker. Sternum 0.55 long, 0.50 wide, light brown with a narrow darker rim. Opisthosoma 1.00 long, 0.80 wide, with Anelosimus pattern, a dark dorsal longitudinal notched fovea, bordered by white. Colular setae smaller than in most other Anelosimus and may be difficult to see under a dissecting microscope. Eyes subequal in size about 0.07 diameter. Clypeus height about 2.6 times AME diameter. Leg I femur 1.25, patella 0.30, tibia 1.10, metatarsus 0.80, tarsus 0.50. Femur I about 5 times longer than wide. Legs pale yellow with distal half of femur I and distal tip of tibia I darker. Tips of femur and tibia of other legs slightly darkened. 2–5 trichobothria dorsally on 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 eight modified setal bases ( Fig. 7C ). Epiandrous gland spigots in two clearly separate groups of 6–7 fusules ( Fig. 7B ). Palpal organ as in Figures 5A , 6A–F . Female ( paratype ): Total length 2.00. Prosoma 0.90 long, 0.75 wide, brown, cephalic area and a narrow rim around the edge of prosoma slightly darker. Sternum 0.60 long, 0.50 wide, brown, slightly darker than male, with a narrow darker rim. Opisthosoma 1.20 long, 0.95 wide, dark gray with a dorsal longitudinal notched fovea, bordered by white. Colular setae smaller than in most other Anelosimus and may be difficult to see under a dissecting microscope. Eyes subequal in size about 0.07 diameter. Clypeus height about 2.6 times AME diameter. Leg I femur 1.05, patella 0.25, tibia 0.90, metatarsus 0.75, tarsus 0.45. Femur I about 5 times longer than wide. Legs pale brown with distal half of femur I and II darker brown and distal tip of femur III and IV and tibia I–IV also 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 5B–C , 7A . Va r i a t i o n Variation in coloration of opisthosoma of both sexes (in alcohol) is large and ranges from grayish with a dull fovea to dark gray with a fovea bordered with sharp white. Similarly prosoma may be pale orange to darkish brown. 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. Embolus varies considerably in length, orientation of embolus base, how tightly it spirals and the exact location within the palpus. Generally if the embolus is fairly short it will be tightly coiled and embolus base oriented upwards, if embolus is long it is often more tightly coiled and base is facing downwards. This variation seems to be continuous and although extremes are easy to separate, intermediates of all kinds exist indicating an intraspecific variation rather than the existence of two (or more) species. Both extremes were frequently found in the same sample. Similarly, in the female genitalia the size of the genital opening and in particular the size of the spermathecae is very variable. However the pathways of the copulatory ducts are similar in all specimens and different than in A. dude .