Featured Article Summary #122

Katipō (Latrodectus katipo) is a venomous cobweb spider found only in New Zealand. It is closely related to the Australian redback and its bite can cause latrodectism, with symptoms such as extreme pain and, in some cases, hypertension or seizures, though bites are rare and antivenom is available in some hospitals. The female is 8–10 mm long and the male is 4–5 mm, and females have different markings depending on where they live, while males are white with black stripes and red hourglass-like marks. The katipō mostly lives in sand dunes near the coast, feeding on ground-dwelling insects caught in tangled webs among dune plants or debris. After mating, females lay several egg sacs in late spring, and the young hatch and spread into nearby plants in summer. The name comes from Māori for “night stinger,” and the species is in serious decline due to habitat loss, invasive spiders, and hybridisation with the redback. The katipō was first recorded in the mid-1800s, but was not formally described until 1870. Since then, scientists described it multiple times under different names and split or merged species, until genetic and other evidence led to the conclusion that L. katipo (including the form atritus) is distinct from the redback spider, L. hasseltii. There was also confusion about whether katipō and L. katipo var. atritus were separate because they look very similar but live in different places. A 2008 revision used genetic data to synonymise them, suggesting their colour differences are gradual variation linked to latitude and temperature, and placing katipō in the genus Latrodectus within the cobweb spider family Theridiidae. The name katipō, also spelled “katipo,” is Māori for “night stinger.” It comes from kakati (to sting) and pō (night), and it is one of the few Māori words that refers to a particular spider species, including the fully black variant called black katipō. A 2004 genetic study compared DNA from the cytochrome c oxidase subunit I gene of Latrodectus spiders and found that the katipō is closest to the Australian redback spider (Latrodectus hasseltii). Because they are so closely related, the katipō was once thought to be a subspecies of the redback, but later work showed it is genetically and physically distinct and prefers a very different habitat. As an adult, the female katipō is 8–10 mm long, or 35–41 mm including the leg span. Red katipō have a black, silky-looking abdomen with a white-edged orange or red stripe along the top and red markings on the underside, while black katipō from the upper North Island lack the top stripe and are generally lighter, with underside hourglass markings that may be less clear. Some black katipō also show rare brown or other color variations. The katipō is most similar to its sister species Latrodectus hasselti but can be told apart by the short hairs on the abdomen; it may also be confused with Steatoda species, especially Steatoda capensis (“false katipō”), which has a shinier, less tapered abdomen and more closely spaced side eyes.