HERPETOLOGICAL JOURNAL, Vol. 13, pp. 1-20 (2003) THE AUSTRALIAN ELAPID GENUS CACOPHIS: MORPHOLOGY AND PHYLOGENY OF RAINFOREST CROWNED SNAKES JOHN D. SCANLON Department of Environmental Biology, University of Adelaide, Australia and Department of Palaeontology, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia The genus Cacophis, comprising four species endemic to eastern Australia, is uniquely derived among terrestrial Australasian elapid snakes in the temporal scale pattern, presence of a relatively high and narrow dorsal crest (‘choanal process’) on the palatine bone, and presence of keeled supra-anal scales in adult males. Recent analyses based on morphology and genetics do not completely resolve relationships among Australasian elapids, but support relationships of Cacophis with the (Furina, Glyphodon) and (Aspidomorphus, Demansia) clades, which are adopted here as outgroups for intrageneric analysis. Within Cacophis, morphoclines in size, head scalation, tooth numbers and colour patterns indicate that C. squamulosus is the sister-group to the remaining three species; among the latter, there is conflicting evidence for both (harriettae, krefftii) and (churchilli, krefftii) clades, but the latter alternative has greater support. Revised diagnoses are given for the genus and included clades, and a simple phylogeographic model proposed. Key words: Hydrophiinae, morphology, skull, head scales, colour patterns, behaviour, phylogeography INTRODUCTION level analysis (cf. Hutchinson, 1990). Such a ‘global’ Numerous studies have contributed to understanding analysis will not be presented here, as I concentrate on a the phylogeny of Australian elapid snakes, providing particular genus and its putative close relatives. evidence for monophyly of a number of genera and of Hutchinson (1990) considered diagnosis of the genus several suprageneric units (e.g. Schwaner et al., 1985; Cacophis problematic, and recognized it only ‘tenta- Mengden, 1985; Shine, 1985; Hutchinson, 1990; Greer, tively’ as distinct from Furina. Cacophis consists of 1997; Keogh, 1998, 1999; Keogh et al., 1998, 2000). four species of small nocturnal saurophagous (lizard- These probable clades include: the ‘subfamily’ eating) snakes, all restricted to rainforest or wet Hydrophiinae comprising all terrestrial Australasian sclerophyll habitats in coastal regions of eastern Aus- elapids as well as marine forms (in either the sense of tralia (Queensland and New South Wales). Three of the McDowell, 1987, or that of Slowinski & Keogh, 2000, species have long been recognized, although they were which differ in whether Laticauda is included); the vi- previously referred to as many as three separate genera viparous radiation (Shine, 1985); the true sea snakes (Cacophis, Aspidomorphus and Glyphodon in Worrell, (here regarded as a monophyletic ‘tribe’ Hydrophiini, 1963). McDowell (1967) suggested that these three spe- despite a recent analysis suggesting diphyly; cies (krefftii, Dwarf crowned snake; harriettae, Rasmussen, 2002); and a ‘Notechis lineage’ comprising White-crowned snake; and squamulosus, Golden- chromosome groups 4, 5 and 10 of Mengden (1985). crowned snake) formed a single natural group distinct However, resolution remains poor because characters from other genera; Cogger (1975) brought them to- have often been inadequately defined or polarized, or gether in Cacophis, and full synonymies are given in insufficiently numerous to resolve the large number of Cogger, Cameron & Cogger (1983). species (e.g. McDowell, 1967; Storr, 1985; Wallach, The fourth species, found in the Wet Tropics of 1985; Greer, 1997; Lee, 1997). I have studied external northern Queensland, was first recognized informally as and skeletal morphology in the terrestrial Australasian ‘Glyphodon sp.’ by Worrell (1963: 125 and plate 56), elapid snakes, attempting to define and test additional and subsequently as Cacophis h. [harriettae] flavicollis characters in order to improve phylogenetic resolution [nomen nudum] (McDowell, 1967: 536) and Cacophis (e.g. Scanlon, 1985) and as a basis for interpretation of sp. (Wilson & Knowles, 1988: 332; Gow, 1989: 84; Miocene fossils (Scanlon, 1996). An important interme- Ehmann, 1992: 392). Cogger (in Cogger et al., 1983: diate goal is to establish the monophyly and internal 219) includes the mentions by Worrell (1963) and relationships of groups of species (e.g. genera) which McDowell (1967) in the synonymy of C. harriettae, but can conveniently be used as discrete units in a higher- notes that both refer to what is probably a distinct spe- cies. The name Cacophis churchilli Wells & Wellington, 1985 is available for this form, though it has Correspondence: J. D. Scanlon, Department of only recently come into wider use (Greer, 1997: 160, Palaeontology, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia. 178; Shea & Sadlier, 1999; Queensland Museum, 2000: E-mail: [email protected] 239; Cogger 2000: 771). Ehmann (1992) calls it the 2 J. D. SCANLON ‘Northern Dwarf Crowned Snake’, but ‘dwarf’ is not es- (Swofford, 2002), in some cases using batch commands pecially appropriate since it attains body sizes similar to generated using TreeRot version 2 (Sorenson, 1999). C. harriettae (see below). While detailed studies of geographic and genetic OUTGROUP RELATIONSHIPS OF CACOPHIS variation remain to be done (J. Sumner in prep.), I re- In order to assess the polarity of morphological char- gard the the identity and boundaries of these species as acters contributing to the diagnosis of Cacophis and now being stable, and a formal revision is not given resolution of relationships among the included species, here. Rather, this paper reviews evidence for relation- relevant outgroups must be identified. Ideally, these ships between Cacophis and other genera, reports should include the two clades most closely related to the observations of some unusual morphological features ingroup to allow the outgroup comparison procedure of contributing to the diagnosis of the genus, and uses read- Maddison et al. (1984). Previous analyses of Australa- ily available data to derive an explicit phylogenetic sian elapid relationships support the basal position of hypothesis for the four included species. Laticauda and the Solomon Island genera (McDowell, One motive for investigation of this genus is the dis- 1970; Keogh et al., 1998), and the monophyly of a large covery of fossil material of small elapid snakes from the viviparous lineage which includes mainly Australian Miocene of northern Australia, including a maxilla with terrestrial elapids and hydrophiine sea snakes (Shine, features resembling those of Cacophis species (Scanlon, 1985; Keogh et al., 1998, 2000). These results imply 1995, 1996). However, as variation in skeletal features that the remaining Australo-Papuan oviparous genera (apart from tooth counts) within the genus is dominated form either one or several clades along the stem lineage by ontogenetic change in proportions (pers. obs.), the of the viviparous group. This intervening part of the tree emphasis here is on external morphology. (including Cacophis) has been poorly resolved by prior work, which is attributable mainly to insufficient sam- METHODS pling of characters and (especially Melanesian) taxa, but All data are drawn either from published sources or perhaps also to the rapidity of the adaptive radiation (cf. examination of specimens – including those in the col- Schwaner et al., 1985; Wallach, 1985; Mengden, 1985; lections of the Australian Museum, Sydney (AMS); Lee, 1997; Greer, 1997). The selection of outgroups Queensland Museum, Brisbane (QM); South Australian must therefore be provisional at this stage. Museum, Adelaide (SAM); and Western Australian Classifications up to that of Worrell (1963, 1970) re- Museum, Perth (WAM). Some additional specimens at ferred at least some Cacophis species to Aspidomorphus the American Museum of Natural History, New York (see Mengden, 1983, for review), but it has since been (AMNH) and Museum of Comparative Zoology, considered that Aspidomorphus is closest to Demansia Harvard (MCZ) were examined on my behalf by M. Lee. (McDowell, 1967; Keogh et al., 1998). Also, a consen- A large number of external and skeletal morphologi- sus has developed that Cacophis is closely related to cal features have been investigated for their potential to Furina and Glyphodon (McDowell, 1967; Wallach, contribute phylogenetic information for Australian 1985; Hutchinson, 1990; Greer, 1997; Keogh et al., elapids, and many of them show overlapping variation 1998; Keogh, 1999). A recent analysis of DNA se- of continuous or discrete characters across species or quence data (Keogh et al., 1998) has found support for a more inclusive groups (Wallach, 1985; Scanlon, 1985; clade comprising Cacophis, Demansia, Lee, 1997). This is consistent with the uncontroversial Aspidomorphus, Furina and Glyphodon. While the de- hypotheses that novel characters (genetic, morphologi- tailed results varied with different methods of data cal, or behavioural) must pass through a stage of analysis, they ‘consistently grouped these four genera in polymorphic coexistence with their alternative, various combinations’ (p. 77), with Demansia and plesiomorphic states before being fixed in one or more Aspidomorphus most strongly linked. As shown in Fig. descendant populations, and that such polymorphisms Cacophis may be retained for evolutionarily significant periods. In many cases, I recognize polymorphic coexistence of Glyphodon