Sprackland, Robert George; (1995) Evolution, systematics, and variation of Pacific mangrove monitor lizards (Reptilia: Squamata: Varanidae). Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The complex of Pacific lizards (Squamata: Anguimorpha: Varanidae) colloquially known as mangrove monitors is reviewed from a morphological perspective to clarify intraspecific variation and interspecific evolution and relationships. The study used a total of 350 museum specimens and 120 live animals, to construct a data matrix for a preliminary set of 77 characters (later reduced to 27). From these, a set of 12 meristic characters were subjected to statistical analysis (principal coordinates and multidimensional scaling), while 27 binary and multistate characters were run using the phylogenetics programme Hennig86 in a novel test of intraspecific and interspecies-group relationships. Individuals, rather than "species", were used as terminal taxa to see how individual-based analysis compares with contemporary species allocations. Morphological data were used to distinguish species from a clade of at least five sister taxa, Varanus doreanus Meyer 1874, Varanus jobiensis Ahl 1932, Varanus spinulosus Mertens 1941, and Varanus finschi Bohme, Horn and Ziegler 1994, plus Varanus indicus*. The apparently well-defined V. indicus (Daudin, 1802) is shown to be composed of widely morphologically divergent individuals that do not clearly segregate into geographical populations. Furthermore, some of these individuals emerge as more closely related to other mangrove monitor species than to members of their "own species". For these reasons, V. indicus is here recognised as a metaspecies (V. indicus*). Further resolution may be possible by analysis of internal anatomy or molecular evolution (e.g., to reveal the presence of cryptic species), although the probable recency of cladogenetic events would make such analyses of limited use.

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