Jan 23, 2016

Wandering Spider: The Final Answer

Two years ago I blogged about a large wandering spider I found inside my Chiriqui home at 3:00 am when my cats created a ruckus and woke me.  I sprayed it with insecticide and after confirming its demise, took some photos. Then I initiated a cursory internet research to identify its species and particulars.  Each time I saw a photo of a beast that resembled my deceased spider, the caption identified it as a phoneutria (Brazilian Wandering Spider).    Somewhere I read about another species (Cupienius) that was oft confused with the phoneutria but lacked the same reputation for being “deadly”.  I spent hours on the internet comparing photos of the two arachnid groupings, attempting to diagnose my night visitor as either harmless or evil. I didn’t want to believe it, but my spider more closely resembled photos of the phoneutria than it did the the cupienius.  
I then decided to call on the experts, and wrote to three online spider websites.  Two of the site masters confirmed my spider was a phoneutria based upon the arrangement of its eight eyes, the black line running down the dorsal carapace, (cephalothorax) and a series of 6 dice-like dots on the dorsal abdomen. Wikipedia also described these features as characteristic of phoneutria.  The last contacted website expert responded saying the spider couldn’t be classified without “seeing it in person”.  I surmised this respondent was too weird for further communication :-)

Given two out of three “experts” had confirmed my fears that the spider was a phoneutria, I published two posts alerting other expats to utilize caution in dealing with such critters in the home. Since then I’ve received occasional emails about the posts and I reiterated to those contacts that my information came from the internet and I had no first hand training or experience in arachnology.  However, I continued to warn people not to be too cavalier in their dealings with large spiders in the home.

Very recently, I received another email, only this time the author was not someone to be placated with generalities.  She wanted to know who I had contacted, why I reached my conclusion, and how dangerous the spider venom actually was.  She reported having found several similar spiders in her home nearby.  I gave her what information I had, but it wasn’t detailed enough and she was determined to get to the bottom of the matter.  I’d love to give her credit here for pursuing the issue, but don’t have permission to use her name.  Suffice it to say her initials are P.C. and I’m grateful for her energy and persistence.  She wrote to the Smithsonian in Panama City, and was directed to someone in Germany who subsequently directed her to another person in Brazil who then forwarded the information to the final expert.

Through photos P.C. sent of one of the spiders she sacrificed, the expert determined the spider was NOT a phoneutria but instead a Ctenus sinuatipes.  The Ctenus species are also wandering spiders, found frequently in Central America, but have not been declared to have “medically significant” venom.  This Brazilian expert recognized the distinctive features of the spider’s back legs (sinew-like) and mentioned this is what gave the species its name. 
I was interested in this information, but had doubts about the classification of my particular spider because it differed from the photos of P.C.’s spider.   I spent several more hours on the internet, trying to teach myself spider anatomy & physiology and blowing up photos of hairy arachnids to better examine magnified eyes and hair follicles.  It got to the point where if a breeze blew past the back of my neck, I jumped three feet.  I finally admitted I was in over my head and decided with P.C.'s blessing to contact this expert myself with photos of my spider. I digress here to mention that the expert is an arachnologist with a PhD, is affiliated with the California Academy of Sciences, has written numerous scientific papers, including a few dealing with the reclassification of tropical spiders, and is female, attractive, young, personable and, at minimum, bilingual.  She has been more than accommodating and helpful regarding our inquiries about the spiders.  I am very confident of and impressed by her knowledge.

This evening I received her response that the spider I’ve been calling a phoneutria for 2 years also happens to be a male Ctenus sinuatipes.  So what does that mean?  Essentially it means it is not considered "dangerous".  Male Ctenus sinuatipes generally live for about 1.5 years and die shortly after mating.  They are known to travel great distances to mate.  Females can live up to 10 years.  A bite from this spider would be painful, and there is always the risk of a anaphylactic allergic reaction that could be serious and/or lethal, however absent a significant allergy to the venom, a person is unlikely to die from a bite.  

Dr. Daniele Polotow elaborates to say that even phoneutria bites are rarely fatal. Having worked more than 10 years for the research institute in Brazil that produces all the spider and snake antivenoms and vaccines for Brazilian hospitals, she reports that the majority of people bitten by these spiders don't receive antivenom.  The treatment standard is observation and palliative care. This includes treatment even for the scientists who work directly with the live spiders collecting venom.  She reports the bite is extremely painful and may cause confusion and other symptoms of neurotoxicity, but is rarely fatal and easily treated.   She then goes on to caution that, despite ongoing research into Central American spiders, a lot remains unknown regarding the effects, toxicity, and symptoms their venoms cause. Better to be safe than sorry.   If one finds it necessary to erradicate a questionable spider, doing so won't endanger the species. Logging, mining, and real estate expansion are the real dangers to species extinctions.

An internet search I conducted in Spanish regarding Ctenus sinuatipes bites turned up a report by the Organization for Tropical Studies data base in Costa Rica of an individual bitten in 1981.  (The spider was captured and later identified as a female Ctenus sinuatipes.  The specimen is registered at the Museum of Zoology in Costa Rica.) The report indicates a 25 yr old woman was gathering laundry on her patio in San Rafael de Coronado when she received a spider bite on her left thumb.   The victim immediately felt intense pain at the bite site, a generalized sensation of fever and diaphoresis, edema, moderate cyanosis and numbness of the hand where a bloody puncture wound was seen at the innoculation point. An hour later she experienced dizziness and fainting, coldness of the hand and tightness in the elbow joint.  Later, she had a headache.  The following day she experienced persistent numbness of the hand.  The third day she had pain that radiated to the elbow upon applying pressure to the bite wound.  On the fifth day she was asymptomatic.  Treatment consisted of intramuscular antihistamines, intramuscular penicillin, and oral analgesics and anti inflammatory medication. 
Internet photo of  Ctenus sinuatipes found in Costa Rica.  Note the sinuous final segments of the hind legs.