Discovery of Six New Bent-Toed Gecko Species in Northeast India

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Context

• Scientists from India and the United Kingdom have recently described six new species of bent-toed geckos from Northeast India.

Details

• The researchers from the Wildlife Institute of India (WII), Ashoka Trust for Research in Ecology and Environment (ATREE), and the Natural History Museum London (NHM) conducted this study. The discoveries include:
• Two Species from Arunachal Pradesh
• Two Species from Nagaland
• Two Species from Manipur and Mizoram

Geographic Distribution and Diversity

• Bent-toed geckos are distributed across multiple biogeographic zones, including Peninsular India, Sri Lanka, the Himalayan foothills, Northeast India, Southeast Asia, and the Solomon Islands.
• With approximately 346 species identified, this group exhibits significant diversity.

 Highlights of New Species Descriptions

• Arunachal Pradesh
  • • Namdapha Bent-Toed Gecko: Documented from the Namdapha Tiger Reserve, this species is widespread in lowland evergreen forests of both the Namdapha and Kamlang Tiger Reserves. This nocturnal species is found along forest streams, rocks, and vegetation.
    • Siang Valley Bent-Toed Gecko: Discovered in the Siang River valley, renowned for its unique biodiversity.

 READ ABOUT NAMDAPHA TIGER RESERVE: https://www.iasgyan.in/daily-current-affairs/namdapha-national-park-and-tiger-reserve

• Mizoram
  • • Ngengpui Bent-Toed Gecko: Found in the Ngengpui Wildlife Sanctuary in Lawngtlai district, located in one of the easternmost protected areas of India. The surrounding forest is characterized by tropical semi-evergreen to moist evergreen vegetation

Ngengpui Wildlife Sanctuary The Ngengpui Wildlife Sanctuary in Mizoram spans 110 square kilometers and is renowned for its dense virgin forest. It is a habitat for diverse wildlife, including elephants, tigers, clouded leopards, gaurs, barking deer, sambar, rhesus macaques, wild boars, hoolock gibbons, and leaf monkeys, as well as various birds like peacock pheasants, imperial pigeons, and hornbills. Located approximately 45 kilometers southwest of Lawngtlai, it lies near the Indo-Myanmar and Indo-Bangladesh borders. The sanctuary ranges from 200 to 1200 meters above sea level and features virgin subtropical evergreen vegetation.

• Manipur
• • • Manipur Bent-Toed Gecko: Discovered near Lamdan Kabui village, perched on a shrub at about 1.5 meters elevation along the road connecting Leimatak and Charoikhullen.

• Nagaland
  • • Kiphire Bent-Toed Gecko: Found in regenerating jhum land at elevations between 740 m and 1,300 m above sea level.
    • Barail Hill Bent-Toed Gecko: Discovered in a reserved forest at similar elevations.

 Research and Implications

• These discoveries were made during surveys conducted from 2018 to 2022, across 22 locations in Northeast India.
• Morphological and scientific tests revealed six new lineages previously undescribed.

 Significance of Findings

• The species diversity is notably higher south of the Brahmaputra River compared to the Himalayan foothills.
• Each Northeastern state now has its own endemic bent-toed gecko species, adding to the approximately 30 species in the region. This underscores the rich biodiversity and the importance of exploring lesser-known areas.
• The findings from protected areas and abandoned jhum lands highlight the poorly documented biodiversity in India’s protected regions and the significance of such neglected areas for undocumented species.

 Geckos

• Geckos are small, predominantly carnivorous lizards found on every continent except Antarctica.
• Belonging to the infraorder Gekkota, they inhabit warm climates worldwide, ranging in size from 6 to 60 centimeters (0.6 to 23.6 inches).

Vocalisations and Diversity

• Geckos are unique among lizards for their vocalisations, which vary by species.
• Most in the family Gekkonidae use chirping or clicking sounds for social interactions. Notable species include the Tokay gecko (Gekko gecko), known for loud mating calls.
• Geckos are the most species-rich lizards, with about 1,500 species

Physical Characteristics

• Eyelids: All geckos except those in the family Eublepharidae lack eyelids. They have a transparent membrane called the brille and a fixed lens that enlarges in darkness to enhance light intake.
• Nocturnal Adaptations: Most geckos are nocturnal and have excellent night vision, with color vision 350 times more sensitive than humans. They possess specialized cone cells and a multifocal optical system.

Specialized Toe Pads

• Many gecko species have specialized toe pads that allow them to climb smooth and vertical surfaces, including indoor ceilings.
• This adhesion is due to the spatula-shaped setae on their feet, which operate through van der Waals forces or possibly electrostatic interactions.

Shedding and Skin

• Shedding: Geckos shed their skin regularly, with frequency varying by species. Leopard geckos shed every 2-4 weeks, while young geckos shed weekly.
• Skin: Gecko skin typically does not have scales but is covered with hair-like protuberances that provide superhydrophobicity and antimicrobial properties.

Teeth

• Geckos are polyphyodonts, meaning they can replace their teeth every 3 to 4 months. Their teeth are pleurodont, fused to the inner surface of the jaw bones.

Evolutionary History

• Gecko ancestors date back to the Late Jurassic. The earliest modern gecko fossils are from mid-Cretaceous Burmese amber, approximately 100 million years old, and show adhesive pads similar to living species.

 Reproduction

• Geckos exhibit diverse reproductive strategies, including egg-laying, live-bearing, and asexual reproduction through parthenogenesis.
• Egg-laying: Most geckos lay small clutches of eggs.
• Live-bearing: Some geckos give birth to live young.
• Parthenogenesis: A few geckos reproduce asexually, where females produce offspring without fertilization. This process involves meiosis with premeiotic endoreplication of chromosomes, allowing for the formation of viable progeny.
  

PRACTICE QUESTION Q. In which state of India is the Ngengpui Wildlife Sanctuary located? A) Assam B) Manipur C) Mizoram D) Tripura  Answer: C)

 SOURCE: DOWN TO EARTH