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Aspects of the distribution, ecology and morphology of Ingram's Brown Pseudonaja ingrami ()

Stephen Phillips University of New England, Northern Rivers, P.O. Box 150, Lismore, New South Wales 2480 Present address: Australian Koala Foundation, GPO Box 9899, Brisbane, 4001

ABSTRACT Ingram's Brown Snake is the least well known member of the elapid Pseudonaja. Recent field work undertaken in southwestern Queensland has extended the known geographic range for the . Aspects of the morphology and ecology of Ingram's Brown Snake suggest that it shares much in common with an unrelated species, the Western Taipan Oxyuranus microlepidotus, to the extent that some confusion could arise in distinguishing between the two. Relevant aspects of the and morphology of Pseudonaja and that of O. microlepidotus are discussed. Downloaded from http://meridian.allenpress.com/rrimo/book/chapter-pdf/2644403/rzsnsw_1993_054.pdf by guest on 24 September 2021

INTRODUCTION extent of the species' geographic range in Queensland is based on only two specimens The genus Pseudonaja comprises seven in the Queensland Museum, both from the currently recognized species collectively dis- vicinity of Boulia in the central west of the tributed across the Australian continent, except state. Other aspects of the species's ecology are for Tasmania. The taxonomy of Pseudonaja is similarly poorly known with the exception that greatly in need of revision (Cogger 1992), with the species appears to feed largely on small at least two species already considered or mammals with both Gillam (1979) and otherwise known to be composite (Mengden Ehmann (1992) suggesting that the Long- 1985; Phillips, unpubl. data; Wallach 1985). haired Rat Rattus villosissimus is an important Ingram's Brown Snake Pseudonaja ingrami is component of the diet. the least well known member of the genus. Originally described by Boulenger (1908), MATERIALS AND METHODS P. ingrami suffered intermittent favour with On the basis of an earlier examination of herpetologists, sometimes being regarded as a specimens held in the Australian and Queens- junior synonym of P. textilis, a congener with land Museums, field collections associated with which it shares many morphological similarities ongoing work by the author related to a revision (Gillam 1979). While Gillam's (1979) work of the genus Pseudonaja were undertaken in further described differences in iris and buccal southwestern Queensland. During January 1992 cavity colour as a means of more readily an area was surveyed on the property "Palparara" distinguishing P. ingrami from P. textilis, these midway between Bedourie and Windorah in characters did not confirm its taxonomic identity southwestern Queensland. Following discussions until Mengden (1985) established that the with station management, which included species was valid, being electrophoretically directions to a localized "rat plague" and distinct and differing in gross karyotype from observations of "Yellow-bellied Black " other members of the genus. in the same area, a 14 kilometre track was The distribution of Ingram's Brown Snake traversed by vehicle between 0730 hours and has been described as the black soil plains of 1000 hrs each day and between 2130 and 2300 the Barkly Tableland (Gillam 1979), "arid hrs each evening for a three day period from black soil plains . . . from the interior of the 19th January. The area in general Queensland to central " conformed to descriptions of Mitchell Grass (Wilson and Knowles 1988) and "lower-lying "Downs" as described by Spriggs and Hill parts of black soil plains ... in areas that (1986), being essentially treeless and covered receive fairly regular monsoonal rains" with a sparse scattering of native grasses on a (Ehmann 1992). Wilson and Knowles (1988) dark brown, cracked soil substrate (Fig. 1). also refer to a localized and apparendy disjunct population occurring in Kununurra, Western RESULTS . The initial evening transect revealed a As demonstrated by the work of Longmore localized population of R. villosissimus approxi- (1986), P. ingrami is poorly represented in mately midway between the "Pigeon" and museum collections and indications of the "Bundi" tanks (Lat: 24°55'S, Long: 141°06'E) Herpetology in Australia 349 All specimens were actively foraging when first observed. P. ingrami forages with the head, neck and about 25 per cent of the anterior body portion raised off the ground. The elevated portion sweeps radially from side to side accompanied by incessant tongue flicking, the head lowering occasionally to partially enter fissures and cracks in the soil. Once disturbed, each snake attempted to retreat into cracks in the soil and exhibited little aggressive behaviour apart from a flattening of the neck area immediately behind the head. All five specimens were retained alive for subsequent genetic and reproductive studies Fig. 1. Mitchell Grass Downs of the Diamantina drainage but will eventually be lodged in the Queens-

basin on Palparara Station, southwestern Queensland land Museum. Downloaded from http://meridian.allenpress.com/rrimo/book/chapter-pdf/2644403/rzsnsw_1993_054.pdf by guest on 24 September 2021 — habitat of Pseudonaja ingrami. Photo: Steve Phillips. on the station. The points at which specimens DISCUSSION of the rat were first observed and subsequently These observations extend the known ceased were marked by rock cairns so that the southern limit for Ingram's Brown Snake in area could be located by day. southwestern Queensland by about 300 km Over the next two days a total of six snakes (Fig. 2). On the basis of soil type and the known were observed along the transect within the distribution of R. villosissimus at least, they area occupied by the R. villosissimus population. suggest a potential southern limit for the Only one snake was observed outside of the species consistent with that area defined as the area occupied by the R. villosissimus population, Diamantina River drainage basin in Queens- despite extensive vehicle and foot-based searches land and possibly extending into the north- of the surrounding countryside. All snakes eastern corner of . Both the were observed between 0800 and 0930 hours observed range extension and the likely EST. Five of the individuals, including the southern limit of the species' geographical isolated specimen referred to above, were range are outside of the bio-climatic predictions captured by hand and examination established of potential range provided for P. ingrami by that all were P. ingrami on the basis of scale Longmore (1986). Periodic floods in the counts and other diagnostic characters described Channel country could also potentially transport below. The average total length of the captured individual specimens even further to the south. specimens was 1 320 mm (range 1 225-1 456); the ventral scale counts averaged 206 (range The three colour morphs observed on 196-212) and the sub-caudals (all divided) Palparara Station are consistent with the averaged 65 (range 58—70). All specimens had descriptions of colour variation in Northern 17 mid-body scale rows and seven infra-labial Territory P. ingrami provided by Gillam (1979). scales. Additionally, both the buccal cavity and More interesting is that they also provided pupil were dark, and the iris was indistinct. evidence of the extent to which starkly con- trasting colour morphs can be present within a Three of the captured specimens were a single population of the same species. While uniform glossy black/brown in dorsal coloura- this phenomena can be observed to a limited tion, the lower lateral body scales displaying a extent in other elapid genera, it is present to light yellow to cream base. A further specimen an extra-ordinary degree in Pseudonaja (see was predominately a glossy dark (burnished Mengden and Fitzgerald 1987), so much so brass) brown, the lower lateral body scales that a minimum of three currently recognized being similar to that described previously. The taxa in the genus and at least two species yet remaining specimen was a uniform glossy to be resurrected from synonomy can be shown orange/brown in colour with the exception of to exhibit superficially similar colour morphs a dark head and nape and with the body scales (Phillips, unpublished data). The ecological occasionally possessing small dark bars on an and/or evolutionary benefit(s) offered by irregular basis. All five specimens had pale to commonly shared interspecific morphological bright yellow ventral surfaces displaying a paired attributes of colour and pattern remain to be series of red to orange spots which decreased addressed for Pseudonaja but have undoubtedly posteriorly in a variety of configurations played a significant role in contributing to the following an area loosely defined as between taxonomic confusion currently associated with the 30th and 40th anterior ventral scales. this genus.

350 Herpetology in Australia Pseudonaja with a maximum total length reported to exceed 1.75 metres (Gillam 1979). The relatively large size attained by individuals of P. ingrami also approximates that reported for O. microlepidotus (Shine and Covacevich 1983). Other aspects of the gross morpholgy of O. microlepidotus include a variety of colour morphs which include both dark and pale forms (Covacevich 1987), the lower lateral and ventral surfaces cream to yellow, occasionally bearing orange blotches (Wilson and Knowles 1988) and a blackish brown iris without a noticeable coloured rim around the pupil (Ehmann 1992). These attributes, coupled with similarities in foraging behaviour, habitat preference, diet and a now broadly over-

lapping geographical range, suggest that O. Downloaded from http://meridian.allenpress.com/rrimo/book/chapter-pdf/2644403/rzsnsw_1993_054.pdf by guest on 24 September 2021 microlepidotus and P. ingrami are sufficiently similar that an individual of one could easily be mistaken for the other in the field, even more so than that already reported for O. micro- lepdotus and P. nuchalis by Covacevich (1981) and Wilson and Knowles (1988). Both the Fig. 2. Map of southwestern Queensland showing location potential for confusion and the extent of of Palparara Station and new locality record (X) for Pseudonaja ingrami referred to in text. superficial similarities is perhaps best evidenced by comparison of the colour figure The extent to which the P. ingrami were of O. microlepidotus featured on the cover of the obviously exploiting the rodent population as work by Longmore (1986), to that of a specimen evidenced by the observations reported in this of P. ingrami from Camooweal (Qld), provided paper support the contention that the distribu- by Cogger (1992). While individuals of both tion and abundance of the species may well O. microlepidotus and P. ingrami can still be depend upon that of R. villosissimus in a distinguished on the basis of scutellation manner similar to that suggested for the (primarily differences in the mid body scale Western Taipan Oxyuranus microlepidotus count [23 vs 17] and configuration of the anal (Covacevich and Tanner 1983; Covacevich scale [single vs divided]) it is recommended 1987). The paucity of specimens of P. ingrami that incidental observations of either species, in museum collections is also similar to that of particularly in the Diamantina and Coopers O. microlepidotus (Longmore 1986), further Creek drainage basins of Queensland and suggesting that the relative scarcity and South Australia, be regarded with scepticism abundance of both species may be linked to in the absence of more detailed information, the population dynamics and periodic plagues or the specimens themselves. of this rodent species. Despite regular field work in the area, P. ACKNOWLEDGEMENTS ingrami was previously unknown from this part This work was undertaken as a component of Queensland, with incidental sightings of of postgraduate studies on Pseudonaja being large elapids generally assumed to be either O. undertaken by the author at the University of microlepidotus or (P. McRae, New England Northern Rivers. Specimens were pers. comm.). However, on the basis of collected under permit from the Queensland collections in the Australian and Queensland National Parks and Wildlife Service and staff Museums, P. nuchalis is noticeably absent from of the Charleville District Office, in particular this particular area of Queensland with the Jim McDonnell and Peter McCrae, provided exception of specimens from Windorah to the valuable assistance and advice on the area. east and Birdsville to the south-west. On the Various property owners including Sandy Kidd basis of findings reported here it is suggested (Windorah) and the Manager of Palparara that P. ingrami may well be the predominant Station were also generous in allowing access "Brown Snake" in the "Channel Country" of to their land. Thanks also to Graeme and Ryan Queensland. Lloyd, Ben Phillips and Ben Regan for their Ingram's Brown Snake is considered to be company. Angus and Karen Emmitt provided the second largest member of the genus a touch of country hospitality and stimulating Herpetology in Australia 351 conversation on the arid zone herpetofauna. MENGDEN, G. A., 1985. A Chromosomal and Electrophoretic Analysis of the Genus Pseudonaja. Pp. 193-208 in The constructive comments of two anonymous Biology of Australiasian Frogs and ed by G. Grigg, referees have assisted completion of this paper. R. Shine and H. Ehmann. Royal Zoological Society of New South Wales: Mosman.

REFERENCES MENGDEN, G. A. AND FITZGERALD, M., 1987. The Paradoxical Brown Snakes. In Toxic Plants and — A Guide for BOULENGER, G. A., 1908. Description of a new elapine snake Australia. Queensland Museum. from Australia. Ann. Mag. Nat. Hist. 1(8): 333-34. SHINE, R. AND COVACEVICH, J., 1983. Ecology of Highly COGGER, H. G., 1992. Reptiles and Amphibians of Australia. A. Venomous Snakes: the Australian Genus Oxyuranus H. and A. W. Reed Pty Ltd.: Sydney. (Elapidae).y. Herpetol. 17(1): 60-69. COVACEVICH, J., 1981. On the resemblance between the SPRIGGS, J. R. AND HILL, G.J. E., 1986. Soils, Vegetation and Western Brown Snake and the Small-scaled Snake. Herpetofauna 12(2): 30. Land Systems. In Queensland — A Geographical Interpre- tation ed by J. H. Holmes. Qld Geogr. J. 4th Series Vol I. COVACEVICH, J. AND TANNER, C., 1983. "Come from nowhere WALLACH, V., 1985. A Cladistic Analysis of the Terrestrial . . . then just disappear". Aust. Nat. Hist. 21(1): 11-13. Australian Elapidae. Pp. 223-53 in Biology of Australa- COVACEVICH, J., 1987. Two Taipans. In Toxic Plants and sian Frogs and Reptiles ed by G. Grigg, R. Shine and H. Animals — A Guide for Australia. Queensland Museum. Ehmann. Royal Zoological Society of New South Wales: Downloaded from http://meridian.allenpress.com/rrimo/book/chapter-pdf/2644403/rzsnsw_1993_054.pdf by guest on 24 September 2021 Mosman. EHMANN, H., 1992. Encyclopedia of Australian Animals (Reptiles). Angus and Robertson: Sydney. WILSON, S. K. AND KNOWLES, D. G., 1988. Australia's reptiles — A Photographic Reference to the Terrestrial Reptiles of GILLAM, M. W., 1979. The genus Pseudonaja (Serpentes: Australia. William Collins Pty Ltd: Sydney. Elapidae) in the Northern Territory. Territory Parks Wildl. Commn Res. Bull. 1: 1-28.

LONGMORE, R. (ed), 1986. Atlas of Elapid Snakes of Australia. Australian Flora and Fauna Series No.7. Bureau of Flora and Fauna: Canberra. Aust. Govt Publishing Service.

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