Katipō

As an adult, the female has a body size of 8–10 millimetres (0.31–0.39 in) or 35–41 millimetres (1.4–1.6 in) if leg span is included. The red katipō, found in the South Island and the lower North Island, has a large black globular abdomen with a silky appearance and a distinctive white-bordered orange or red stripe on its upper surface that runs from the beginning of the abdomen back to the spinnerets. The underside of the abdomen is black and has a red patch or partial red hourglass-shaped marking. For the black katipō, found in the upper North Island, the abdomen differs in not having the upper red/orange stripe and is overall somewhat lighter in colour. The hourglass pattern on the underside of the abdomen may also be less distinct, losing the middle section. Rare variations in black katipō also exist where the abdomen, cephalothorax, or entire body is brown, sometimes with a dull red or yellow stripe, or cream-coloured spots on its upper side. The katipō is most similar to its sister species Latrodectus hasselti. The katipō can be distinguished from L. hasselti by the short setae (hair-like spines) of the abdomen, whereas on the abdomen of L. hasselti it is a mix of long and short setae. There are also minor differences in the shape of the female and male genitalia structures. It may also be confused for Steatoda species, which are often present in the same habitat. …

The katipō is only found in New Zealand. In the North Island it is found throughout the West Coast from North Cape to Wellington. On the east coast of the North Island it occurs irregularly, but it is abundant on Great Barrier Island. In the South Island it is found in coastal regions south to Dunedin on the east coast and south to Greymouth on the west coast. It has been proposed that this southern limit is due to the katipō needing warmer temperatures to allow for the development of their eggs. The red katipō is found south of the western tip of Taranaki on the west coast, and just north of Waipatiki Beach in Hawke's Bay on the east coast. The black katipō are found north of Aotea Harbour in the Waikato region on the west coast, and Waipiro Bay in the Gisbourne region on the east coast. Both forms are found in a transitionary area in between these aforementioned localities. These colour variants are strongly correlated with temperature, one study reporting that the red katipō is found in cooler areas with average temperatures of 11.24–13.85 °C (52.23–56.93 °F). In contrast, the black katipō is found in warmer areas with average temperatures of 13.64–16.23 °C (56.55–61.21 °F).

Habitat. The katipō is restricted to coastal sand dunes near the seashore. …

Once it becomes an adult, the male begins to search for a female with which to mate, possibly being guided by pheromones in female's silk. The male enters the female's web and gently vibrates the silk as he approaches her. The female is usually aggressive at first and will chase the male from the web. The courtship process consists of the male bobbing, plucking and tweaking the web along with periods of cautious approach and being chased by the female. Eventually, she becomes docile and allows him to approach. The male moves to the underside of her abdomen, tapping her rapidly until their abdomens are aligned in the same direction. He then inserts his palps (appendages modified for reproduction) into the female's reproductive tract one at a time. Copulation occurs over 10 to 30 minutes. After mating, the male retreats to groom, which is performed by running his palps and legs through his fangs and wiping them over his body. The male is not eaten by the female unlike some other widow spiders.

The female lays its eggs in November or December. The eggs are round, about the size of a mustard seed, and are a transparent, purplish red. They are held together in a cream-coloured, round, ball-shaped egg sac which is about 12 millimetres (0.47 in) in diameter. The female constructs five or six egg sacs over the next three to four weeks. …

The common name and specific name katipō (singular and plural), often spelt "katipo", is Māori for "night stinger", derived from the words kakati (to sting) and pō (the night). It is one of the few Māori words that refers to a specific species of spider. The fully black variant is referred to as black katipō.