New Zealand's giant Collembola: New information on distribution and morphology for Holacanthella Börner, 1906 (Neanuridae: Uchidanurinae)

The New Zealand collembolan fauna currently includes five described species of the striking endemic genus Holacanthella (springtails). Holacanthella species are saproxylic decomposers of cool temperate forest ecosystems, and they contribute to nutrient cycling of coarse woody debris. All species of the genus have the dorsal and lateral surfaces furnished with conspicuous red, orange, yellow or white digitations. They are among the largest Collembola known, with some individuals reaching 17 mm in length. We examined new material of the five species from throughout New Zealand, as well as existing museum material, to understand more fully their distributions. We provide an updated key to the five Holacanthella species and discuss the conservation of rare/range restricted species, and propose hypotheses to explain their distributions. One species, H. laterospinosa, is known only from Cuvier Island and the Coromandel Peninsula, North Island, but the distributions of the remaining four species appears to reflect the turbulent geological history of New Zealand during the Pliocene. Intraspecific variation in several gross morphological characters was observed in all species. We provide a comparison of characters with the other genera within the Uchidanurinae in order to characterise the genus more fully with respect to allied genera. Holacanthella species are particularly vulnerable to human‐mediated disturbance by forest modification because of their strict habitat requirements and low mobility, and we stress that conservation efforts should focus on protecting critical habitats for each species.