The Fine Surface Structure of the Male Genital Bulb of the Dwarf Spider Catabrithorax Plumosus
The spider Catabrithorax plumosus (Emerton) family Linyphiidae, subfamily Erigoninae is a member of an abundant yet reclusive group known as the dwarf spiders. Collectively, these are the smallest spiders in North America. Most measure only 1-3 mm in length, creating difficulties in indentification. The morphology of the male genital bulb, located on the distal pedipalp, is of great importance to the taxonomist in identifying spiders to the species level. This study examines the complex male genital structure in both the expanded and unexpended condition by means of the Scanning Electron Microscope (SEM).Pedipalps were removed at the trochanter-femur articulation, dehydrated in 70% ethanol and expanded by Immersion in lactic acid for 6-8 h. After complete expansion a graded amyl acetate series preceeded critical point drying. Unexpanded palps were dehydrated in an ethanol series followed by a graded amyl acetate series in ethanol. Specimens were critical point dried from CO2 and given an evaporated coating of carbon-gold. Specimens were examined in a Hitachi HHS-2R Scanning Electron Microscope operating at an accelerating voltage of 10 kV.