66 ENTOMOLOGICAL NEWS DRY WEIGHT OF FRESH AND PRESERVED SPIDERS (ARANEIDA: LABIDOGNATHA) 1 Robert L. Edwards 2 , Wendy L. Gabriel 3 ABSTRACT: Data on the dry weight for 1 9 taxa (suborder Labidognatha) of fresh and preserved spiders are presented. The variation in weight at length for individual species is also provided. With the notable exception of the genus Tetragnatha, Family Tetragnathidae, the Family Theridi-idae, and most of the genera of the Family Thomisidae, the families examined are similar to one another in their weight-length relationships and are not readily separable on that basis. Dry weight can be approximated using either the weight of fresh specimens or preserved material. The 'typical' spider, based on the material examined, increases in length faster relatively than it increases in weight, and dry weight decreases relative to fresh weight as length increases. With the exception of the papers by Clausen, 1983, that included data on fresh and dry weight-length relationships for nine species (five families), and Breymeyer, 1967, for three species of the family Lycosidae, there is very little general information available on the dry weight of spiders. This report serves to increase the information available on spider weight and explores the degree of difference between taxa from the weight-length perspective. MATERIAL AND METHODS The bulk of preserved material was collected in 1989 and 1990 in the Frances Crane Wildlife Management area, Hatchville, Falmouth Township, Barnstable County (Cape Cod), Massachusetts, in connection with another study (Edwards 1993). Collection details are provided therein. All were preserved in 75% denatured ethanol and all had their alcohol replaced at least once, typically within 48 hours of collection. The total length was measured from the clypeus to the distal end of the abdomen using an ocular micrometer for specimens < 1 2 mm in total length and vernier calipers for those > 1 2 mm. The total length, as described above, was measured to the nearest 0.1 mm, and the specimens damp dried on absorbent paper before weighing. Obviously distorted speci-mens were not used. In those cases where the pedicel had elongated, the sepa-ration of the thorax from the abdomen was measured and the total measure-ment corrected accordingly. The fresh material for this study was collected in the months of June through September, 1996, from the same area and habitats as the preserved material with one exception. The collection of Leucauge regnyi Simon, Family Tetra-gnathidae, was made in Puerto Rico in September, 1996. All collections were 1 Received April 9, 1997. Accepted July 7, 1997. 2 Research Associate, United States National Museum, Box 505, Woods Hole, Ma. 02543 3 Wendy L. Gabriel, Northeast Fisheries Center, 166 Water St., Woods Hole, Ma. 02543 ENT. NEWS 109(1): 66-74, January & February, 1998
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