Squat lobsters are not lobsters in the culinary sense. They are decapod crustaceans of the infraorder Anomura, the same group that includes hermit crabs and king crabs, and most species are small, laterally compressed animals that shelter in crevices or perch on hard substrates, waving their elongated claws in the current to feed. The family Munidopsidae, to which the new species belongs, is dominated by deep-water lineages, many of which are associated with seamounts, canyons, and other hard-bottom habitats far below the reach of sunlight-driven photosynthesis. Because these environments are geographically isolated from continental shelves and exhibit complex topographic and oceanographic patterns, they often harbor distinctive benthic communities, including endemic species found nowhere else.

The specimens that led to the new species were collected in late March 2024, during FORV Sagar Sampada cruise 404, using a chain bag dredge deployed at a station located at 8.54 degrees North, 73.26 degrees East, on what the team designated seamount 4 off Minicoy. Four individuals were recovered: an ovigerous female designated as the holotype, one male and two females designated as paratypes. All four came from the same dredge haul at 360 meters depth, collected by R. Ravinesh and his shipboard colleagues. The animals are small even by squat lobster standards, with postorbital carapace lengths ranging from about 4.5 to 5.2 millimeters and carapace widths between 3.7 and 4.4 millimeters.

Back in the laboratory, the team cleaned, photographed, and examined the specimens under a Leica M80 stereo-zoom microscope fitted with a high-definition camera, taking measurements with calibrated imaging software. The morphological analysis followed the descriptive terminology established in a 2019 revision of the genus by Rodríguez-Flores, Macpherson, and Machordom, which had itself described fifteen new species and remains the taxonomic backbone for Leiogalathea. Every appendage was scrutinized: the spination of the third maxillipeds, the proportions of the first pereopods, the armature of the walking legs, the shape of the rostrum, and the pattern of ridges sculpting the carapace, the armored plate that covers the head and thorax.

That ridge pattern proved decisive. Leiogalathea samudragiri shares with three of its closest relatives, L. achates, L. evander, and L. laevirostris, an unarmed hepatic margin on the carapace, a feature that initially groups them together. But the new species stands apart in two consistent characters: its mesogastric and mid-transverse ridges on the carapace are uninterrupted, running continuously across the midline, and the posterior half of the carapace bears six transverse ridges. In the three related species, the mid-transverse ridge is interrupted medially or submedially, and only four or five ridges follow it. Additional differences reinforce the split. Unlike L. achates, the new species lacks a spine on the posterior branchial margin and has subequal rather than unequal distal spines on the second antennal article. Unlike L. evander, it carries three well-developed rostral teeth rather than four to six rudimentary ones, and its abdominal tergite 3 bears a single elevated ridge rather than two. Unlike L. laevirostris, the basal antennular article is unarmed at its distomesial corner, and the mesial margin of the first pereopod’s carpus carries one spine rather than three.

The detailed anatomy is a study in miniature engineering. The rostrum, the pointed projection between the eyes, is slightly downturned and flattened dorsally, about 1.5 times as long as broad, with serrated lateral margins bearing three small teeth and three progressively smaller rudimentary teeth. The first pereopods, the elongated claws that give squat lobsters their characteristic silhouette, extend to nearly three times the carapace length and are clothed in uniramous stiff setae, with the merus segment alone slightly exceeding the carapace length and bristling with strong spines arranged along its mesial, dorsal, lateral, and ventral surfaces. The walking legs are moderately slender and laterally compressed, with propodi more than five times as long as broad and dactyli armed with rows of small, proximally diminishing teeth, each tipped with a slender movable spinule. The third maxilliped’s ischium terminates in a strong spine on its flexor margin and carries a crista dentata of twenty-two corneous denticles.

Even the coloration, recorded from freshly collected material, is distinctive and unexpectedly vivid for an animal living in near darkness. The rostrum and the anterior two-thirds of the carapace are bright orange, with light yellow patches on the posterior gastric region; the posterior carapace and anterior abdominal segments are pale orange, and the pereopods are bright orange marked with white patches. The species name itself is a nod to its habitat, combining the Sanskrit words samudra, meaning ocean, and giri, meaning mountain, a direct reference to the seamount where the animals were found. The holotype female was ovigerous, carrying eggs, which suggests the population was reproductively active at the time of collection.

The broader context makes the find more significant than a single addition to a checklist. The genus Leiogathea, established by Keiji Baba in 1969, is dominated by the Pacific Ocean, which hosts fourteen of its species, while the Atlantic and Indian Oceans had only two each before this description. The munidopsid fauna of the Northern Indian Ocean, the authors note, remains relatively unexplored compared with neighboring regions. A previous expedition had already yielded an unresolved Leiogalathea specimen from the Andaman Sea, reported as Leiogalathea sp. because it was damaged, hinting that the region harbors more diversity than the formal record reflects. The authors also point out that overlapping morphological characters among congeners probably indicate the existence of pseudocryptic species within the genus, externally near-identical lineages that only careful comparison of fine structural details, or genetic analysis, can separate.

The expedition itself is part of a larger national effort. The samples were gathered under India’s Deep Ocean Mission, specifically the Samudrayaan program, coordinated through the Ministry of Earth Sciences, with CMLRE in Kochi leading the faunal exploration aboard the research vessel Sagar Sampada. Seamounts have been recognized as ecological hotspots since faunal explorations began in the 1940s, yet only a handful of Indian Ocean seamounts have ever been surveyed, leaving vast tracts of undersea topography biologically uncharted. Voucher specimens of the new species, registered under the catalog numbers IO/SS/ANO/00195 through 00197, are deposited in the Bhavasagara Referral Centre at CMLRE, which serves as the regional node of the Ocean Biodiversity Information System for the Indian Ocean, and the associated occurrence data will be made publicly available through the OBIS portal.

For now, Leiogalathea samudragiri is known only from its type locality in the Lakshadweep Sea off Kerala, at 360 meters depth, a single seamount station in an ocean basin where deep-water sampling effort remains sparse. Whether the species is a narrow endemic restricted to one undersea mountain, as many seamount-associated invertebrates appear to be, or simply under-collected across a wider range, will only be resolved by further expeditions. What the discovery does demonstrate is that even a single dredge haul, examined with the right taxonomic expertise, can reveal a lineage new to science in one of the most heavily trafficked yet least explored marine regions on Earth, and that the census of life on the Indian Ocean’s seamounts has barely begun.

Subject of Research: Taxonomic description of a new deep-sea squat lobster species from an Arabian Sea seamount

Article Title: A new deep-sea munidopsid squat lobster of the genus Leiogalathea Baba, 1969 (Decapoda: Anomura) from the southeastern Arabian Sea, India

Article References: Tiwari, S., Padate, V. P., & Cubelio, S. S. (2026). A new deep-sea munidopsid squat lobster of the genus Leiogalathea Baba, 1969 (Decapoda: Anomura) from the southeastern Arabian Sea, India. Discover Oceans, 3(1), Article 6. https://doi.org/10.1007/s44289-026-00117-5

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00117-5

Keywords: squat lobster, Leiogalathea samudragiri, seamount, Arabian Sea, deep sea, taxonomy, new species, Munidopsidae, Decapoda, Anomura, Deep Ocean Mission, marine biodiversity

The headline finding is a stark contrast between scale and knowledge. Mauritius commands an Exclusive Economic Zone of roughly 2.3 million square kilometers and depends heavily on marine resources for food security and economic development. Yet while the island’s corals, fishes, and seagrasses have received sustained research attention, its crustaceans have not. No recent comprehensive inventory or checklist exists. The most detailed records date back to the nineteenth and early twentieth centuries, when naturalists such as H. Milne-Edwards and E. J. Miers described species from what was then known as L’Île de France. Paul Carié’s early twentieth-century work documented 147 decapod species across stomatopods, anomurans, macrurans, and brachyurans, laying a foundation that subsequent researchers have struggled to update.

The review compiles records from 61 crustacean families in Mauritius, with the crab families Xanthidae and Portunidae, the spider crabs of Epialtidae, and the hermit crabs of Diogenidae among the most frequently reported. But the authors caution that this apparent diversity should be interpreted carefully. Many records come from historical surveys whose species names and classifications may no longer align with modern taxonomy, and older literature remains incompletely digitized. Research effort has also been heavily skewed: from the late twentieth century onward, work focused largely on peracarid crustaceans, particularly amphipods and isopods. Christine Appadoo and Derek Steele’s 1998 study recorded 69 gammaridean amphipod species, including numerous new records and undescribed taxa, and later work by Guerra-García on caprellids and by other teams on isopods and hermit crabs added new species and Western Indian Ocean records.

Recent decades have seen only sporadic contributions, such as investigations of sponge-associated crustaceans, the rediscovery of the sponge crab Cryptodromia fallax, and the description of the lobster Enoplometopus holthuisi. The authors argue that the existing literature is better viewed as a historical baseline than a faithful snapshot of current diversity. They call for an updated checklist incorporating verified taxonomy, recent field surveys, molecular identification, and detailed distributional data, along with a reference library of DNA barcodes deposited in public databases such as NCBI and BOLD to support future biodiversity studies and detect whether historically reported species still persist.

Why does this gap matter so much? Globally, crustaceans are among the most functionally important animals in the ocean. They occupy nearly every trophic position, serving as primary consumers, detritivores, predators, and prey. Krill dominate the diets of mobulid rays, calanoid copepods sustain certain jellyfish, and the swimming crab Charybdis smithii feeds yellowfin tuna and pygmy sperm whales. In Mauritius, crustaceans have been reported as the dominant prey of albacore tuna, which uses Mauritian waters as a spawning ground, and decapods have turned up in the stomachs of apex predators from Mauritian and Réunion waters. Predators as large as gray whales track the abundance of benthic crustacean prey, meaning that shifts in crustacean populations can ripple through entire food webs and reshape the distribution of commercially vital fish stocks.

Crustaceans are also the ocean’s cleanup crew and its engineers. As scavengers, they process dead organic matter and can, in some ecosystems, break down up to 75 percent of available plant-derived organic material, with amphipods proving especially dominant from coastal shallows to hydrothermal vents. Burrowing thalassinidean crustaceans are considered among the most effective marine bioengineers: their bioturbation redistributes sediments and nutrients, enhances oxygenation, and stimulates microbial activity and nitrogen cycling. Evidence of these functions in Mauritius is thin but suggestive—crab burrow abundance has been used as an indicator of ecosystem recovery in the island’s mangrove forests—but the broader role of crustaceans in Mauritian nutrient cycling and sediment dynamics remains essentially unstudied.

The review also highlights the striking symbiotic lives of crustaceans, from obligate coral-dwelling trapeziid crabs that defend their pocilloporid hosts against corallivores, to coral gall crabs, to elaborate triple symbioses in which a goby, a pistol shrimp, and a porcellanid crab share a single burrow to mutual benefit. In Mauritius, however, documented symbioses are limited to scattered observations such as crabs inhabiting sponges and barnacle associations, leaving a rich field of research essentially untouched. Economically, the picture is equally lopsided. Fisheries and aquaculture contribute roughly 10.3 percent of Mauritius’s GDP excluding tourism and employ up to 10,000 people, yet in 2023 the country exported only about USD 187,000 worth of crustaceans while importing USD 16.2 million, mainly from India, Madagascar, and Vietnam—a trade imbalance that exposes the island to global price shocks and signals untapped potential for local production, aquaculture, and blue-economy growth.

Then there is chitin. Extracted from crustacean shells and processing waste, chitin and its derivative chitosan are finding applications across medicine, agriculture, and environmental technology: wound dressings and tissue-engineering scaffolds, antimicrobial and anticancer materials, plant-defense biostimulants and biopesticides, and adsorbents that strip heavy metals and arsenic from water. Crustaceans themselves serve as bioindicators, accumulating heavy metals, microplastics, and nanoplastics in ways that reveal ecosystem contamination. A systematic review has even identified Mauritius among the African countries with the highest reported use of marine animals, including crustaceans, in traditional medicine. Yet the biotechnological and pharmaceutical potential of Mauritian crustaceans remains almost entirely unexplored.

Climate change looms over all of it. Atmospheric carbon dioxide has climbed from about 278 ppm pre-industrially to over 421 ppm by 2023, driving ocean acidification projected to lower global pH by roughly 0.4 units by 2100. The Indian Ocean warmed by approximately 0.7 degrees Celsius between 1982 and 2021, faster than other basins. These stressors act on crustaceans at every level, from DNA repair and protein synthesis to haemolymph chemistry, immune function, molting, calcification, reproduction, and behavior. Flic en Flac lagoon offers site-specific warning signs: maximum sea surface temperatures rose from 29 degrees Celsius in 2000–2001 to 31 degrees by 2017–2019, while pH has become increasingly variable. Meanwhile, hard and soft coral cover in parts of Mauritius declined by roughly 40 and 83 percent respectively between 2004 and 2019, and lagoon sponges declined by up to 40.2 percent—collapses that threaten the habitat-dependent and symbiotic crustaceans relying on these structures.

Responses to acidification vary widely among species and over time. Crustaceans may tolerate acidification better than some calcifiers because their exoskeletons are largely calcite-based and rely on bicarbonate, but chronic exposure has been linked to reduced claw hardness, exoskeletal thinning in king crabs, altered mineral composition in shrimps, and delayed post-moult hardening. Behavioral changes add another layer of vulnerability: warming can push shrimps to forage recklessly in the presence of predators, acidification impairs mud crab foraging, and combined stressors disrupt the acoustic signaling of snapping shrimps. Warming and hypoxia also reshape disease dynamics, potentially raising infection risks in both wild populations and future aquaculture operations. The review’s authors are explicit about what comes next: Mauritius needs updated biodiversity inventories, integrative taxonomic and molecular research, long-term monitoring across coral reefs, seagrass meadows, and mangroves, and targeted multi-stressor studies of climate impacts. Without that effort, declines among poorly known, endemic, or economically important crustaceans could unfold silently, invisible beneath waters the nation depends upon.

Subject of Research: Marine crustacean biodiversity and climate-change vulnerability in Mauritius

Article Title: Current knowledge of marine crustaceans in Mauritius and their global importance in a changing climate

Article References: Bhuvaneshwaree, S., Nadeem, N., Sunita, F., & Mandić, J. (2026). Current knowledge of marine crustaceans in Mauritius and their global importance in a changing climate. Discover Oceans, 3(1), Article 61. https://doi.org/10.1007/s44289-026-00171-z

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00171-z

Keywords: marine crustaceans, Mauritius, biodiversity, climate change, ocean acidification, ocean warming, Malacostraca, Decapoda, chitin, fisheries, ecosystem engineers, Indian Ocean