Journal of Threatened Taxa | www.threatenedtaxa.org | 26 June 2025 | 17(6): 27163–27166

 

ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) 

https://doi.org/10.11609/jott.8979.17.6.27163-27166

#8979 | Received 27 November 2024 | Final received 15 March 2025 | Finally accepted 19 June 2025

 

 

First record of marine isopod Synidotea variegata (Collinge, 1917), (Crustacea: Isopoda: Valvifera) from the Gulf of Kutch, Gujarat, northwestern coast of India

 

Deep D. Dudiya ¹, Mansi S. Goswami ^{2  &} Pranav J. Pandya ³

 

^1,2,3 Department of Zoology, R.R. Lalan College, Bhuj, Kachchh, Gujarat 370001, India.

¹ Department of Earth and Environmental Science, Krantiguru Shyamji Krishna Verma Kachchh University, Bhuj, Kachchh, Gujarat 370001, India.

¹ deepdudiya1911@gmail.com, ² mansi3gs@gmail.com, ³ pranavpandya1@yahoo.com (corresponding author)

 

 

Citation: Dudiya, D.D., M.S. Goswami & P.J. Pandya (2025). First record of marine isopod Synidotea variegata (Collinge, 1917), (Crustacea: Isopoda: Valvifera) from the Gulf of Kutch, Gujarat, northwestern coast of India. Journal of Threatened Taxa 17(6): 27163–27166. https://doi.org/10.11609/jott.8979.17.6.27163-27166

 

 

Abstract: Synidotea variegata (Collinge, 1917) is associated with the sea urchin Stomopneustes variolaris (Lamarck, 1816), where it is frequently found inhabiting the spaces among the spines, and around the peristomial region. Previously, this species was known only from the southwestern coast of India. This study reports the presence of the isopod S. variegata in the Gulf of Kutch, Gujarat, northwestern coast of India.

 

Keywords: Association, Crustaceans, Crustacean diversity, host infection, marine isopod, range extension, rocky inter tidal.

 

 

Valviferan isopods are characterised by a dorsoventrally flattened body and a slight but distinct differentiation of body segments, features that aid in their adaptation to benthic environments. These isopods are distributed circumglobally and are predominantly found in shallow coastal habitats rich in algae and seagrass. Their flattened morphology facilitates movement and concealment among dense vegetation, providing both camouflage from predators, and access to detrital and algal food sources (Poore 2012). Valviferan isopods typically have a body where two or fewer of the rear segments (pleonites) can move, while the rest are fused. In some species, only up to four pleon segments are visible from the top, marked by partial or complete lines (sutures), though they do not move. The head is usually separate from the first body segment and is not expanded to the sides. Their mouthparts include a maxillipedal palp (a sensory and handling appendage) usually made up of five segments, though sometimes the last segments are fused. The first pair of walking legs (pereopods) is only slightly adapted for grasping, while the remaining legs (second to seventh) are all similar, and used for walking. In males, the reproductive organs (penes) are close together and may be free, partially fused at the base, or completely fused. Their tail limbs (uropods) have a free inner branch (endopod) but lack an outer branch (exopod). The bases of the swimming limbs (pleopods) are all about the same length, and the first pleopod in males is not modified. Females have flat, plate-like structures called oostegites on their front walking legs (either the first four or five pairs), which together form a brood pouch used to carry and protect their developing young (Collinge 1918; Poore & Ton 1993; Song & Min 2017).

Gujarat State, from western India, covers approximately 2,340.62 km of coastline, i.e., up to 21% of the Indian coastline (TRW-MoPSW 2025). A wide range of maritime ecosystems, such as mangroves, coral reefs, rocky coasts, mudflats, sandy shorelines, and estuaries, have been found throughout Gujarat’s coastline, adding to the state’s abundant marine biodiversity. A number of researchers have attempted to explore the marine variety of this region (Apte 1998; Singh et al. 2004; Venkataraman 2004; Satyanarayana 2009; Dixit 2010). The diversity of corals and crustaceans in this region receives considerable attention. The state’s and the nation’s crustacean diversity has been the subject of noteworthy research (Pandya & Vachhrajani 2013; Trivedi et al. 2018; Beleem 2019). Nonetheless, nine species from the Gujarat coast have been identified to date (Trivedi et al. 2015; Valarmathi 2024), representing the diversity of isopods among different groups of crustaceans.

In the present study, Synidotea variegata (Collinge 1917) is reported for the first time from Gujarat State, India, and thus also making a new addition in the Gulf of Kutch.

 

Materials and Methods

Live specimens of Synidotea variegata (Collinge, 1917) were collected during low tide from the northern Gulf of Kutch, along the Kutch coastline, using hand-picking. Following collection, the isopods were cleaned, photographed, and preserved in 70% ethanol for future research, following Ravinesh & Kumar (2022). Specimen identification was based on the diagnostic characters provided by Yesudas et al. (2021). The samples were deposited in the Zoological Reference Collection at the Zoology Department of R.R. Lalan College, Bhuj (RRLC-ZC).

 

Results and Remarks

Family: Idoteidae Samouelle, 1819

Genus: Synidotea Harger, 1878

Type species:  Synidotea variegata Collinge, 1917 (Image 1a–d)

Synidotea variegata Collinge, 1917 In Yesudas et al. 2021: 84, p. 107 fig. 1–c.

Material examined: 11.ii.2023, 1 Male, length 8.32 mm, max. breadth 3.39 mm rocky intertidal region of Kachchh coast (22.836° N & 69.225° E), near Mandvi, Gujarat, India, coll.. M. Goswami, D. Dudiya.

Diagnosis: Body oblong-ovate, dorsal surface is convex and almost smooth (Image 1). Animal colouration pale to golden yellow. Frontal margin straight, the posterior region has a deep transverse furrow, and the cephalon wider than the length and narrows posteriorly. Perionites 2-4 are expanded; perionite 5–7 gradually narrow down.  First joint of antennule broad, while the second and third are short, broad, and subequal (Image 1a,b,d). Pleotelson nearly 1.5 times as long as wide with narrow rounded apex. A short denticulate spine is found on the outer posterior margin of the uropod, which has nearly straight lateral sides except at the hinge (Image 1). The endopodite, on the other hand, has a straight inner margin and is cut away on the outer side. Uropods are armed with denticulate spine terminally. Rest of the characters agree with the descriptions given by earlier researchers (Collinge 1917; Yesudas et al. 2021).

Colouration: The species is mostly seen under rocks. The body is yellowish coloured, decorated by minute black pigments. The head region is somewhat depressed, circular, with the anterior area somewhat flat. Eyes are laterally placed and oval.

Remarks: This species demonstrates a close relationship to Synidotea harfordi Benedict, 1897 and S. angulata (Collinge, 1917). It varies from both in several structural traits. It coincides with the earlier species in the shape of the cephalon and in possessing the little rounded median notch or depression on the posterior border of the metasome. In the context of mesosomatic and metasomatic segments, it has a resemblance to S. angulata.

Distribution: Kerala, Tamil Nadu (Yesudas et al. 2021), and Gujarat (present study) (Image 2).

 

Conclusion

Synidotea variegata (Collinge, 1917) is typically found inhabiting rocky intertidal and shallow subtidal zones, where it shelters among crevices, algae, and sessile invertebrates. This study presents the first confirmed record of S. variegata from the Gulf of Kutch, Gujarat, located along the northwestern coastline of India. The discovery significantly extends the known distribution range of the species along the Indian coastline. Until now, S. variegata (Collinge 1917) had only been documented from the southeastern and southwestern regions of India, particularly from the coastal waters of Tamil Nadu and Kerala. Its presence in the Gulf of Kutch suggests a broader ecological tolerance, adaptability to varying salinity and habitat conditions, and may also point to gaps in previous biodiversity assessments in the region. This finding underscores the need for continued monitoring and documentation of marine isopods in underexplored habitats along the Indian coastline.

 

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