Scientists had known that New Guinea was home to a unique species of crocodile since the New Guinea crocodile (Crocodylus novaeguineae) was officially described in 1928, but since then, they have wondered if the island was actually home to two separate species, one in the north and one in the south. A new analysis of museum and live specimens of the New Guinea crocodile answers the question: yes.
“The New Guinea crocodile is a freshwater species of crocodilian endemic to the island of New Guinea in northern Oceania. The species inhabits both the country of Papua New Guinea in the east and Indonesian West Papua,” said Dr. Caleb McMahan, an integrative tropical biologist at the Field Museum of Natural History, and his colleagues.
“It occurs on both the northern and southern side of the Central Highlands, which span east to west dividing the entire island into northern and southern halves. Like most crocodilians, it inhabits various grassy and forested swamps in lowland freshwater areas.”
In the new study, Dr. McMahan and co-authors examined 51 Crocodylus novaeguineae skulls from seven museum collections, analyzing differences between crocodiles that lived in the northern and southern parts of the island.
In addition, they examined live individuals at the St. Augustine Alligator Farm Zoological Park in Florida.
They wanted to see if the stark differences found in their research were as recognizable to the eye as they were within the data.
The northern and southern crocodiles proved different enough that the researchers were able to declare the ones from the south separate species, named the Hall’s New Guinea crocodile (Crocodylus halli) for Philip Hall, the late scientist who sowed the seeds for the project.
“Understanding these populations as separate species opens the door for more thorough conservation assessments,” the study authors said.
“It could be that when we consider crocs on the whole island, they might be okay, but if we start looking at a species north of the highlands and one south of the highlands you might find more habitat degradation and population threats in one over the other,” Dr. McMahan said.
“This highlights the importance of attention to ecology and conservation for both lineages.”
Christopher M. Murray et al. 2019. Divergent Morphology among Populations of the New Guinea Crocodile, Crocodylus novaeguineae (Schmidt, 1928): Diagnosis of an Independent Lineage and Description of a New Species. Copeia 107 (3): 517-523; doi: 10.1643/CG-19-240