Friday, October 28, 2016

Brown Recluse Spiderling

I was recently given a very worn specimen of the spiderlings that are infesting our friend's house.  It measured 1/10th of an inch and had been dead on an alcohol pad for several days.  The parent hasn't been seen and their concern was are these Brown Recluse?  If this was our house on the creek I would say 90% likely but she needed better odds. 

Compare fiddle below
The Brown Recluse (Loxosceles  reclusa) is in the Sicariidae Family.  The genus Loxosceles, known as the Brown Spiders, has 11 species that includes the Brown Recluse.  There are several diagnostic features of this family.  First, the legs and abdomen have a uniform color with no spots or stripes.  Second this family has only 6 eyes, unique among all other spiders which have 8.  These eyes are arranged in a "U" " shaped configuration.

  Clay Nichols CC
The most well known feature of the Recluse is the fiddle on the thorax.  The fiddle is more prominent and the fiddle neck is thinner in most photographs so this bothered me.  There are several possible explanations.
  1. This specimen had been dead several days and may have lost some color.
  2. It might have been preparing to molt with some separation of its cuticle.
The coloration and the arrangement of the 6 eyes puts it in the Loxosceles genus.  According to the site, only L. reclusa occurs in the Midwest with the remainder isolated along the Mexican border so this is as close to a full ID as I can get.

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