Habitat‐adapted communication in Trite planiceps, a New Zealand jumping spider (Araneae, Salticidae)

Abstract

The natural history and intraspecific interactions of Trite planiceps, a common New Zealand jumping spider (Salticidae), are described for the first time and discussed in relation to this salticid's unusual microhabitat ‐ the rolled‐up leaves of New Zealand flax (Phormium tenax) and similar plants. In many respects, T. planiceps’ display and mating behaviour resembles other salticids. Males have conditional courtship and mating tactics, and the tactics used depend on the female's maturity and location. If in the light, the male uses vision‐based courtship and mates in the open; if at a nest (inside a rolled‐up leaf), the male uses vibratory courtship and mates inside the rolled‐up leaf; if the female is immature but within c. 10 days of maturing, the male cohabits until the female matures and then mates inside the rolled‐up leaf. Regardless of which mating tactic is used, after males mount females there is a phase during which the pair are in physical contact and communicate using tactile signals ('post‐mount courtship'). Other sex and age classes of T. planiceps also communicate using visual displays when in light, away from rolled‐up leaves, and also sometimes employ tactile signals when at nests or during escalated contests in the light. In addition to these typical salticid characteristics, T. planiceps has some atypical display behaviours that appear to be adapted for communicating in its unusual habitat. Even when no conspecific has been encountered, T. planiceps males sometimes display when approaching openings of rolled‐up leaves occupied by conspecific females. These displays closely resemble visual displays used while facing a conspecific in the light. Later, while entering the cavites within rolled‐up leaves and while moving about inside simulated rolled‐up leaves (glass tubes kept away from visible light and observed using infra‐red video), males and females use vibratory displays, tapping the leaf surface with Legs I and vibrating their abdomens, even when no conspecific has been encountered. Finally, when spiders interact within simulated rolled‐up leaves, they appear to communicate using both tactile signals and vibratory signals that are transmitted through nests or leaf surfaces. Many other salticids use nests as a medium for transmission of vibratory signals. However, T. planiceps’ use of the leaves forming its nesting microhabitat for this function is unusual. This is the first study in which infra‐red video has been used to observe interactions between salticids under conditions of total darkness for the spider, and also the first report of a salticid possessing a display repertoire for use in darkness but away from nests. We emphasise adaptation for typical habitat as a partial explanation for species differences in salticid communication systems.

Keywords:

• communication
• displays
• salticid
• spiders
• Trite planiceps