Researchers have discovered the largest orb-weaving spider ever seen, a (relatively) massive creature whose body is about 1 1/2 inches across and whose legspan reaches 5 inches. A second group has found a specimen that is perhaps a little less creepy, although somewhat disturbing for different reaso

ns — a vegan spider.

The newly discovered orb weaver, called “Nephila komaci,” was discovered in Madagascar and Africa by a team led by Matjaz Kuntner of the Slovenian Academy of Sciences in Ljubljana. Nephila spiders are the largest web-spinning species, creating circular webs as large as 3 feet in diameter.

They are also good subjects for studying sexual dimorphism because only females grow large. Males are about one-fifth the size of females, as small as common household spiders.

Kuntner and his colleagues reported in the online journal PLoS One that they originally found the new species as a preserved specimen in the collection of the Plant Protection Research Institute in Pretoria, South Africa. Several expeditions to South Africa failed to find a living example, and researchers thought perhaps it had gone extinct.

Finally, however, a South African colleague found a male and two females living in the Tembe Elephant Park in Kwazulu-Natal, South Africa, confirming that the species was still around. The new species was named after Kuntner’s best friend, Andrej Komac, who encouraged him to pursue his doctorate but died in an accident about the time of the initial discoveries.

The species becomes one of more than 40,000 known species of spiders. Until recently, researchers had believed that all 40,000 subsisted primarily on insects, although some have been known to supplement their diets with plant nectars and pollen.

But two years ago, while watching jumping spiders on an acacia plant in Mexico, entomologist Christopher Meehan, now at the University of Arizona but then a graduate student at Villanova University, observed a very strange behavior.

The spider “Bagheera kiplingi” (named in the late 1800s after the panther in Rudyard Kipling’s “Jungle Book”) ignored the copious numbers of ants covering the plant, crawling over them to eat nectar from the tips of leaves.

The acacia and the ants have a mutually beneficial relationship in which the ants protect the plants from most would-be herbivores by biting them. The plant, in turn, provides the ants with housing via swollen hollow spines and food, including nectar and the contents of specialized leaf tips called Beltian bodies.

“B. kiplingi” is an interloper on this relationship, stealing the food without giving anything back to the plant.