Intraspecific interactions of Holoplatys sp. indet., a New Zealand jumping spider (Araneae: Salticidae)

Abstract

The display repertoire of Holoplatys sp. indet. is unusually large and complex for a salticid spider. Approximately 27 major displays occur, a number comparable to the maximum repertoire sizes recorded for vertebrates and social insects. Males have 3 different mating tactics, the one used depending on the female’s maturity and location. With adult females outside nests, males use ‘type 1’ courtship; this is shown experimentally to be a form of visual communication, and includes specialised movements of the legs and palps. With adult females inside nests, males use ‘type 2’ courtship; this does not depend on vision, and includes elements such as probing and palpating on the silk while outside, and tapping and brushing the female after entering the nest. With subadult females, males first use type 2 courtship and then spin an adjacent silken chamber and cohabit. After the female moults and matures, mating occurs inside her nest. Post-mount courtship is a non-visual phase that precedes copulation and occurs as a component of each tactic. Females, subadults, and juveniles display also, and different combinations and sequences of displays occur, in accordance with the sex/age class and location of each interacting spider. One display of females, ‘thumping’, has an unusually pronounced releaser effect on male mounting behaviour. Although well fed spiders never killed displaying conspecifics, they frequently killed and ate ones that failed to display. Starved spiders, however, often killed displaying conspecifics. A hypothesis is advanced to explain the effectiveness of displays in protecting spiders from cannibalism. The functions of displays are discussed.

Keywords:

• Araneae
• Salticidae
• Holoplatys sp. indet.
• behaviour
• displays
• courtship versatility
• cannibalism