Vibrant, tiny, and sporting a bright red grin on its back, the Happy-Face spider is one of the most famous and recognisable arachnids in the world. For over a century, this cheerful-looking creature was thought to be a unique resident of the Hawaiian Islands, a biological curiosity found nowhere else on Earth.
When researchers from the Forest Research Institute and the Regional Museum of Natural History discovered a new species of spider with the same unmistakable smile in the montane mountains of Uttarakhand, India, they knew exactly what to call it: Theridion himalayana , the Himalayan Happy-Face Spider.
"The discovery was accidental because our survey was [originally] on ants", said Devi Priyadarshini, a scientist at the Regional Museum of Natural History who co-authored the study. "But my co-author [Ashirwad Tripathy] kept sending me spiders from high altitude regions for identification. So, one fine day, when he shared this image from the underside of a Daphniphyllum leaf, I froze in shock because I had seen the Hawaiian spider during my master's programme itself, and I knew instantly we had a jackpot because of its striking resemblance. I asked him to send all morphs that he found, and that led to the discovery in the next few months, from October 2023 onwards."
Priyadarshini added that she was always interested in exploring high-altitude spiders because the landscape and vegetation are so different there than in the plains. "This almost came across as a gateway to look at other polymorphic species from this region." Ashirwad also said that we could find more variations in the species if the surveys could be done extensively.
The species name, himalayana, serves as a tribute to the mountain range where the spider was found at elevations of over 2,000 meters above sea level. "The name Himalayana was decided as the species name because we both wanted to pay our respects to the mighty Himalaya mountain ranges, which have been standing tall not just guarding our country but also holding a plethora of biodiversity within them", Ashirwad said. "Since this spider was the first polymorphic from this region, we decided to make it an ode to the amazing mountain ranges."
The research , published in the open-access journal Evolutionary Systematics , identified 32 different colour variations, or "morphs", of the species collected from three locations in Uttarakhand: Makku, Tala, and Mandal. DNA analysis revealed a genetic variation of approximately 8.5% from the Hawaiian happy-face spider, confirming it as a separate lineage that evolved independently in Asia.
While the smiling patterns are striking, their exact purpose remains a mystery. "The reason behind the expression of polymorphism is also very complex and unique", Priyadarshini explained. "These patterns definitely help them survive better in the wild, which is understood prima facie, but why do they resort to such patterns on their back, and what functional role in their life cycle does it exactly serve is yet to be deciphered. This is definitely indicative of a deeper genetic mystery." Ashirwad also mentioned that the spider species was surrounded by critters which had similar colour patterns on their body.
The study also noted that these spiders are frequently found on ginger plants (Hedychium species), mirroring the behaviour of their Hawaiian cousins. Since ginger is not native to Hawaii, the researchers are intrigued by the evolutionary connection. "How did the spiders choose an invasive species and ginger exactly?" Priyadarshini noted. "If T. himalayana is an elder cousin of T. grallator, although discovered 125 years later! Although this sounds like a tall claim now, it will be our further scope of work to establish any missing links, if at all, through Hedychium sps."
