On the Discovery of the Emerald Tree Monitor

We have researched the history of the type description and holotype of the Emerald Tree Monitor. Our investigation revealed four important details: These are 1) the collecting situation of the first Varanus prasinus specimen in New Guinea in July or August 1828; 2) its first pictorial representation created there in the field, a watercolour by Pieter van Oort, that is published here for the first time (and which was recently made available online by the Naturalis museum in Leiden); 3) the engravings in connection with Hermann Schlegel’s scientific descriptions of the species in three separate, but connected publications in 1839, 1841, and 1845; and 4) the descriptions (in part jointly published with Salomon Müller), connected with these and being, together with the naming, the actual, overarching scientific goal. Schlegel’s first description in 1839 was preceded by John Edward Gray’s (1831a) reference to the “Green Monitor”, Monitor viridis, a “nomen dubium” according to Mertens (1963), aspects, that led to a, so far, inadequately clarified nomenclatorial situation around this name. Because the later holotype of Monitor prasinus had doubtlessly not yet arrived in Leiden at the time of Gray’s visits to this museum collection, it remains unclear which specimen Gray referred to. In order to shed light on this open question, we provide a new perspective on the events of this historical context. In addition, Müller’s handwritten descriptive note about V. prasinus, dated August 1828 and probably produced in New Guinea briefly after having caught the later holotype, has been discovered in the archives of Naturalis and is presented here also for the first time in printed form. Müller’s knowledge about the morphology of monitor lizards becomes obvious not only in his abundant notes and descriptions — besides an astonishing number of snake, gecko, agamid, and skink species — but especially in the joint description of Monitor prasinus together with Schlegel in 1845. In addition, we clarify the correct publication date of Schlegel’s original description of M. prasinus in his treatises called “Abbildungen neuer oder unvollständig bekannter Amphibien, nach der Natur oder dem Leben entworfen und mit einem erläuternden Texte begleitet”, which were issued in five parts between 1837 and 1844. This is also relevant for other reptile and amphibian species that were named for the first time in this work