Taxonomic and Zoogeographic Studies of the New Zealand Scincidae

Abstract

This revision of the New Zealand Scincidae recognises twenty-two species, contained in the genera Leiolopisma Duméril and Bibron and Cyclodina Girard. The following species have been redescribed: L. fallai McCann, L. suteri (Boulenger), L. smithi (Gray), L. homalonotum (Boulenger), L. moco (Duméril and Bibron), L. infrapunctatum (Boulenger), L. latilinearum McCann, L. zelandicum (Gray), L. nigriplantare (Peters), L. lineoocellatum (Duméril and Duméril), L. grande (Gray), L. otagense McCann, L. (?) fasciolare (Girard), C. ornata (Gray), C. aenea Girard, C. oliveri (McCann), C. alani (Robb), C. macgregori (Robb). Leiolopisma (?) fasciolare is included in Leiolopisma, pending further examination and doubts regarding its inclusion in the New Zealand herpetofauna are raised. Four new species are proposed; three in Leiolopisma and one in Cyclodina. Only two subspecies are recognised, in L. nigriplantare, one of these including animals described earlier as L. dendyi (Boulenger) and L. turbotti McCann. L. otagense is viewed as two forms, but these are not given subspecific status. Hinulia variegata Buller is declared a nomen dubium. Electrophoretic studies of lactate dehydrogenase (LDH) isozymes and hemoglobin proteins appear to confirm the species as recognised by their morphological characteristics. Analyses of LDH isozymes suggest close phylogenetic relationships between three groups of species; Leiolopisma latilinearum and L. zelandicum, Cyclodina ornata and C. aenea, and C. oliveri, C. alani and one new Cyclodina species. Investigations into the evolutionary stability of hemoglobins compared with that of morphological characters, indicate that differing rates of evolution may occur, both within and between species. Evidence is presented to show that evolution of hemoglobins cannot necessarily be taken as having occurred at similar rates overall in the New Zealand skink species. It is suggested that Cyclodina arose from a pre-Leiolopisma stock, before the development of the palpebral disc, characteristic of Leiolopisma. The genus Leiolopisma is thought to have arisen in a region north of Australia and given rise in that area, to two early offshoots. The first of these is represented by L. spenceri and L. palfreymani and the second by L. telfairi and L. lichenigera. Subsequent dispersal of the genus is believed to have been via the New Caledonian region, where further divergence resulted in forms now present in Australia (L. coventryi and L. entrecasteauxi) and New Zealand (all .Leiolopisma species). The New Zealand Leiolopisma species are all endemic at the specific level and are likely to represent late Pliocene invasions. The Australian Leiolopisma species characterised by fused frontoparietals are considered to represent a second invasion of that continent from the New Caledonian region. Cyclodina probably reached New Zealand via the New Caledonian region, at least by the early Pleistocene. The genus has not been recorded from outside New Zealand, although revision of the generic allocation of L. euryotis from New Caledonia is necessary, owing to the strong affinities of that species with Cyclodina. Inability to determine the effects of early Pleistocene glaciations on the distribution and isolation of the New Zealand species, limits the discussion of their zoogeography. Nevertheless, three geographic groups of species are recognised in the New Zealand Leiolopisna. The northernmost group is believed to have resulted from a southern movement of invaders from the New Caledonian region. The central and southern groups are thought to have arisen from an easterly movement of invaders from Australia. L. suteri probably represents an invasion separate from the other species. The present distribution of species indicates the following South Island refuges that persisted during the last Pleistocene glaciation: coastal Fiordland, Southland and Stewart Island, Otago and Banks Peninsulas and the Nelson/Marlborough Sounds region. Isolation of populations in the Otago and Banks Peninsula regions, have probably been important in the divergence of two forms within L. otagense. Hemoglobin analyses indicate relict populations of L. nigriplantare at Te Anau and on Stewart Island and a post-Pleistocene reinvasion of the central South Island, by that species, is shown. Subspeciation of L. nigriplantare on the Chatham Islands is thought to have occurred during post-Pleistocene times. Both ecological factors and inundation of the central North Island during Pleistocene interglacials are considered as having been important barriers to dispersal throughout the North Island, by Leiolopisma species in the central and northern groups. Northward movement of L. infrapunctatum to south Auckland Province and Bay of Plenty has probably taken place since the last Pleistocene glaciation. Rafting was the likely means of dispersal of species to the Three Kings and Poor Knights Island groups, although the lowering of sea-levels during Pleistocene glacial periods would have enabled overland dispersal to the majority of islands or island groups now present. The only species apparently endemic at the specific level to an island group, is L. fallai on the Three Kings islands. Initial divergence of Cyclodina species apparently occurred in the northern half of the North Island, with subsequent southward dispersal. The majority of species have probably dispersed throughout much of the North Island in Recent times, although this is now particularly evident only in C. ornata and C. aenea. It is thought that such dispersal must have been variously interrupted by Pleistocene conditions, with Cook Strait becoming an important Recent barrier to continued southward movement. Considerable morphological divergence of C. aenea and C. oliveri, particularly, on the Poor Knights Islands and C. ornate, on the Three Kings Islands, indicate long periods of isolation of these populations.