A researcher has identified a new species of marine crab living in the muddy intertidal mangrove forests along the west coast of India. The newly named crab, Chhapgarus ngankeeae, was discovered by researcher Sameer Kumar Pati from the Zoological Survey of India. Pati made the discovery by taking a closer, microscopic look at preserved specimens from Goa, Karnataka, and Maharashtra that had previously been misidentified as a different species. This discovery highlights how many of the large specimen collections in India remain incorrectly identified.

The story of the discovery began when Pati re-examined crabs from the National Zoological Collections that had previously been identified as the known species Pseudograpsus intermedius (now known as Chhapgarus intermedius). The main reference specimen used to define the new species, the holotype, was collected from beneath a stone in the muddy backwaters of the Galgibag River in Goa. By analysing the crabs under a stereo microscope, Pati realised these specimens had distinct anatomical features that set them completely apart from any known crab.

While Chhapgarus ngankeeae is a small crab, measuring only about 1.6 centimetres across its squarish, brown, hairy shell, it has several unique physical characteristics that make it stand out to experts. The most crucial differences are found on the crab's underside. The new species features a noticeably narrower abdomen (the male pleon), with its second and third abdominal segments equal in width. Its tailpiece, or telson, is as broad as it is long. The most distinctive characteristic, however, is the shape of the male reproductive organ (the first gonopod); its hard, chitinous tip features two conspicuously unequal lobes that form a deep V-shaped constriction, serving as a unique structural fingerprint for the species.

The name, Chhapgarus ngankeeae, honours the late Dr Ngan Kee Ng, a highly respected marine biologist from the National University of Singapore. The name serves as a tribute to her immense, lifelong contributions to the taxonomy and understanding of brachyuran crabs, especially the grapsoid family to which this new crab belongs.

Discoveries like this are incredibly important because mangrove crabs play a vital role in keeping coastal environments healthy, helping to recycle nutrients and maintain the food web. Despite their ecological and even commercial value, the mangrove habitats along the western coast of India remain heavily underexplored. Researchers emphasise that finding Chhapgarus ngankeeae is a strong reminder that we need more extensive surveys in these muddy habitats. Looking to the future, scientists hope to collect fresh specimens for DNA analysis to further unravel the evolutionary family tree of these fascinating coastal crustaceans.