Interesting finding on morphological variation due to geographical isolation of little known squirrel species at Hon Lao Island in Cu Lao Cham Archipelago, central Vietnam

Hon Lao is one of the islands of the Cu Lao Cham Archipelago, located off the coast of central Vietnam. This is a famous tourist destination with beautiful scenery and rich ecosystem, and is one of the biosphere reserves of the world. The fauna here also includes many interesting things.

The red squirrel Callosciurus finlaysonii is a common squirrel species distributed in Thailand, Southern Laos, Southwestern Vietnam, Southwest Cambodia and South Central Myanmar, with about 16 subspecies, with morphological variety, especially fur color. In Vietnam, 2 subspecies were recorded. A population of red squirrels has been recorded in Hon Lao Island in some recent studies. Within the framework of the Project under the Basic Science Development Program in the field of Chemistry, Life Science, Earth Science and Marine Science for the period 2017-2025 (Code: KHCBSS.02/20–22), a research group from the Institute of Ecology and Biological Resources, under Vietnam Academy of Science and Technology, in collaboration with scientists from the University of Natural Sciences (Vietnam National University, Hanoi), University of Tokyo of Japan has collected and discovered interesting features of the red squirrel's fur on Cu Lao Cham Island, in Tan Hiep Island commune, Hoi An city, Quang Nam province.

Orientation map of Hon Lao Island – The area recorded red squirrel species - Callosciurus finlaysonii with variable morphology

Photograph of a red squirrel with variation in morphology recorded at Hon Lao Island - an isolated island off the coast of central Vietnam

Based on the research, comparing and contrasting the morphological features of the fur and the skull structure, it has been noted that the different characteristics of the color of the red squirrel in Hon Lao Island compared to the subspecies of the squirrel species. Callosciurus finlaysonii has been previously recorded in Vietnam and around the world. According to the results of molecular biology analysis of DNA, the squirrel subspecies recorded on Hon Lao Island belongs to the species group C. erythraeus - finlaysonii”, closely related to C. finlaysonii, but having features closely related to C.e.flavimanus. Research has recorded a new form of red squirrel endemic to Hon Lao Island. The results also provide hypotheses and perspectives on the role of geographical isolation in phylogenetics.

Photograph of the out-of-standard morphology of C. finlaysonii recorded at Hon Lao Island

Photograph of standard skull morphology of C. finlaysonii recorded at Hon Lao Island

Research results published in international journals: Tu Ngoc Ly, Son Truong Nguyen, Masaharu Motokawa, Duong Thuy Vu, Hai Tuan Bui, Phuong Huy Dang and Tatsuo Oshida (2021) Geographic isolation created distinct pelage characteristics in Finlayson’s squirrel on isolated island offshore of the Indochina Peninsula in Central Vietnam. Acta zoologica Academiae Scientiarum Hungaricae 67(4): 403-415 DOI:10.17109/AZH.67.4.403.2021

Translated by Tuyet Nhung
Link to Vietnamese version

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