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First distributional record of Stenothoe lowryi Azman, 2023 (Amphipoda: Stenothoidae) from Indian Coast and notes on additional morphological characters

Published online by Cambridge University Press:  02 March 2026

Shreeraj Nahak ,
Gitanjali Bhoi ,
Suman Patra  and
Shesdev Patro Open the ORCID record for Shesdev Patro [Opens in a new window]
Shreeraj Nahak
Affiliation:
Department of Marine Sciences, Berhampur University, Bhanja Bihar, Odisha, India
Gitanjali Bhoi
Affiliation:
Department of Marine Sciences, Berhampur University, Bhanja Bihar, Odisha, India
Suman Patra
Affiliation:
Department of Marine Sciences, Berhampur University, Bhanja Bihar, Odisha, India
Shesdev Patro*
Affiliation:
Department of Marine Sciences, Berhampur University, Bhanja Bihar, Odisha, India
*
Corresponding author: Shesdev Patro; Email: shesdevpatro@yahoo.com
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Abstract

Amphipod samples were collected from the rocky habitat of Arjyapalli beach in southern Odisha, India. The specimens were analysed for morphological characters. One interesting species was observed during the study and was identified as Stenothoe lowryi. The species was previously reported only from Malaysia. The present study confirms the distributional range extension of this species to Indian waters and details a few additional morphological characters.

Keywords

amphipoddistributiondiversityIndiamarine

Information

Type
Marine Record
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 106 , 2026 , e29
Copyright
© The Author(s), 2026. Published by Cambridge University Press on behalf of Marine Biological Association of the United Kingdom.

Introduction

Amphipods are an ecologically significant group of benthic macroinvertebrates, widely distributed in marine, brackish, and estuarine habitats, where they play important roles in detritus processing and serve as bioindicators of environmental change. Despite their ecological importance and diversity, the amphipod fauna of many regions remains poorly documented, with several taxa still underrepresented in faunal surveys (Lowry, Reference Lowry2000; Azman et al., Reference Azman, Sivajothy, Shafie, Ja’afar, Wongkamhaeng, Bussarawit, Alip, Lee, Metillo and Won2022).

Stenothoe Dana, Reference Dana1852 is a genus belonging to the subfamily Stenothoinae Boeck, Reference Boeck1871, within the family Stenothoidae Boeck, Reference Boeck1871. Species of Stenothoe are typically associated with sessile invertebrates such as sponges, ascidians, and cnidarians, although they also occur in intertidal and subtidal habitats (Krapp-Schickel and Vader, Reference Krapp-Schickel and Vader2015). The genus can be distinctly identified by lacking mandible palp, linear basis of P5, widened basis of P6 and P7 and a laminar telson (Krapp-Schickel and Vader, Reference Krapp-Schickel and Vader2015).

Globally, the genus is represented by 63 species (Horton et al., Reference Horton, Lowry, De Broyer, Bellan-Santini, Copilas-Ciocianu, Corbari, Costello, Daneliya, Dauvin, Fišer, Gasca, Grabowski, Guerra-García, Hendrycks, Hughes, Jaume, Jazdzewski, Kim, King, Krapp-Schickel, LeCroy, Lörz, Mamos, Senna, Serejo, Souza-Filho, Tandberg, Thomas, Thurston, Väinölä, Valls Domedel, Vonk, White and Zeidler2025). From India, three species have been documented: Stenothoe gallensis Walker, Reference Walker1904, recorded from Tamil Nadu (Nayar, Reference Nayar1959; Sivaprakasam, Reference Sivaprakasam1966; Venkataraman, Reference Venkataraman2007) and the Bay of Bengal (Surya Rao, Reference Surya Rao1972); Stenothoe kaia Myers, Reference Myers1985, reported from the Lakshadweep Islands (Susan et al., Reference Susan, Raj and Madhu2014); and Stenothoe valida Dana, Reference Dana1852, reported from Tamil Nadu (Gravely, Reference Gravely1927; Sivaprakasam, Reference Sivaprakasam1967) and the Bay of Bengal (Surya Rao, Reference Surya Rao1972). The present study reports the first record of the stenothoid amphipod Stenothoe lowryi Azman, 2023 from the Indian coast, based on specimens collected from the rocky intertidal zone of Arjyapalli, Odisha, on the eastern coast of India. Additional morphological features observed in the examined material are also described.

Materials and methods

The specimens were collected by hand picking from the rocky intertidal zone of Arjyapalli beach, Gopalpur, east coast of India (19°18′14.256″N, 84°57′ 55.512″E). The amphipods were transferred into 90% ethyl alcohol. The morphological characters were observed under the microscope (Nikon SMZ745T Stereozoom). The body parts were dissected, mounted on slides and observed under microscope (Olympus BX53) for detailed characterization. The illustration and line drawings were prepared using Inkscape software. The specimens were deposited in the Estuarine Biology Regional Centre, Zoological Survey of India (ZSI/EBRC).

Abbreviation used in Figures: M = Male; G1, G2 = Gnathopod 1, 2; P3–7 = Pereopod 3–7; U1–3 = Uropod 1–3; T = Telson.

Results

Amphipoda Latreille, Reference Latreille1816

Family Stenothoidae Boeck, Reference Boeck1871

Genus Stenothoe Dana, Reference Dana1852

Stenothoe lowryi Azman, 2023

Figs. 1–3

Figure 1.

Microscopic image of Stenothoe lowryi Azman, 2023, female, ZSI/EBRC/Cr-18901.

Figure 2.

Stenothoe lowryi, male, ZSI/EBRC/Cr18899, Scale bar: 0.1mm).

Figure 3.

Pereopod 3-7 and Uropod 1-3 of Stenothoe lowryi, male, ZSI/EBRC/Cr18899, Telson of female, ZSI/EBRC/Cr-18901. Scale bars: P3–P7 = 0.1mm; U1–U3 and T = 0.05mm.

Materials examined

India • Odisha, Arjyapalli. 1 male; Length 4.17 mm; 19°18′14.256″N, 84°57′ 55.512″E; Rocky habitat; 20.01.2025; ZSI/EBRC/Cr-18899. 1 female; Length 2.65 mm; 19°18′14.256″N, 84°57′ 55.512″E; Rocky habitat; 20.01.2025; ZSI/EBRC/Cr-18900. 1 female; Length 2.94 mm; 19°18′14.256″N, 84°57′ 55.512″E; Rocky habitat; 20.01.2025; ZSI/EBRC/Cr-18901.

Description

Head. Eyes round. Antenna 1 long, subequal to antenna 2, peduncle not geniculate, peduncular article 1, 2× longer than broad, flagellum slightly longer than peduncle, accessory flagellum absent, primary flagellum 20 articulate. Antenna 2 peduncle subequal to flagellum, peduncular article 2 longest. Maxilleped inner plate well separated, triangular with a pair of apical setae. Outer plate with few setae in the inner margin and surface, outer margin clean. Palp four articulate with 3rd article relatively longer. Fourth article of the plap is unguiform with numerous setae on surface.

Pereon. Gnathopod 1 subchelate; basis elongated, posterior margin smooth and anterior margin with two setae; merus rectangular, enlarged and produced distally; carpus triangular, shorter than merus; propodus subrectangular in shape, 2× as long as broad, palm oblique, having two bifid setae at the distal end of the palm, posterior margin and surface with long simple setae; dactylus simple and subequal to plam. Gnathopod 2 large, subchelate; merus posterior margin crenulated and with simple setae; carpus surface margin with a triangular, blunt projection with three apical setae; propodus narrow, oval, and without posterodistal expansion, anterior margin convex and posterior margin more or less straight, about 2× as long as wide, palmar margin moderately convex, posterior margin with brush setae, distal margin with a large spine at the posterodistal corner and a small spine with simple setae at the centre, anterior margin with a pair of setae; dactylus long, acute, both anterior and posterior margins granulated, posterior margin with dense setae and anterior margin with eight setae.

Pereopod 3–7 setose, merus posterior margin expanded. Pereopod 4 coxa large. Pereopod 5 basis not expanded. Pereopod 6 basis expanded, posterior margin straight. Pereopod 7 basis proximally slightly expanded 1.5× as long as broad, posterior margin convex slightly and crenulated.

Pleon. Uropod 1 peduncle with distoventral robust setae; exopod longer than endopod; exopod with three and endopod with two marginal setae. Uropod 2 endopod subequal to exopod; rami with single robust seta on medial margin. Uropod 3 uniramus; and ramus biarticulated; article 1 with a pair of marginal robust setae and article 2 without any marginal setae; article 2 slightly longer than article 1 and proximally swollen, anterior margin with four minute setae. Telson laminar, with distolateral robust setae, apically subacute.

Discussion

This species exhibits distinct diagnostic characters that clearly separate it from morphologically similar congeners, including S. gallensis Walker, Reference Walker1904, S. andamanensis Krapp-Schickel, Reference Krapp-Schickel and Vader2015, S. nhatrangensis Marin & Sinelnikov, Reference Marin and Sinelnikov2018, and S. irinae Marin & Sinelnikov, 2018 (Azman, Reference Azman2023). Stenothoe lowryi differs from S. gallensis, S. andamanensis and S. nhatrangensis by having moderately convex propodus palm of male gnathopod 2 (concave or moderately concave in all three species) and one robust seta in the uropod 2 rami medial margin (two or more robust setae in all three species). Stenothoe lowryi differs from S. irinae by having straight posterior margin of the coxa 2 (rounded in S. irinae) and non rugose surface of the article 2 of uropod 3 (rugose in S. irinae). Stenothoe lowryi Azman, 2023 was originally described from the rocky intertidal zone of Pangkor Island, Malaysia, based on specimens collected from the Straits of Malacca.

Since its description, S. lowryi has been known only from its type locality, with no subsequent records reported elsewhere. The present study confirms its occurrence along Indian coast. The present article details few additional morphological characters which were not mentioned in its original description. The inner plate of the maxilleped is triangular with a pair of apical setae (not mentioned in Azman, Reference Azman2023), the carpus of gnathopod 2 with a triangular blunt projection with three apical setae (not mentioned in Azman, Reference Azman2023 whereas can be marked in the illustration), the dactylus of gnathopod 2 is coarsely granulated (not mentioned in Azman 2023 whereas can be marked in the illustration), rami of uropod 1 unequal (mentioned as equal in Azman, Reference Azman2023; however, illustration shows as unequal), anterior margin of the second article of uropod 3 with 4 minute setae (not mentioned in Azman, Reference Azman2023).

This record from the rocky intertidal zone of Arjyapalli, Odisha, provides further evidence of its ecological association with hard-substrate intertidal habitats. Its presence along the eastern coast of India also extends the known geographical distribution of Stenothoe lowryi beyond its previously restricted type locality in Malaysia. With this new occurrence, the documented diversity of the genus Stenothoe in Indian waters increases to four species, thereby contributing to a more comprehensive understanding of the regional amphipod fauna.

Acknowledgements

The authors express their sincere thanks to the Vice Chancellor, Berhampur University, for providing necessary laboratory facility. The first and fourth author extends their sincere thanks to the Odisha State Higher Education Council, Government of Odisha, for providing the extramural research funding under MRIP-2024.

Author contributions

S. Nahak: conceptualization, sample collection and processing, analysis, led the original draft; G. Bhoi: Species identification; S. Patra: Manuscript drafting; S. Patro: Species identification, conceptualization, write – reviewing and editing, supervision. All authors contributed critically to the manuscript and gave final approval for publication.

Data availability

Needful data can be provided upon request.

Funding

The current research is funded by the Odisha State Higher Education Council, Government of Odisha, through the extramural research funding under MRIP-2024.

Competing interests

None.

Ethical standards

Not applicable.

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Figure 0

Figure 1. Microscopic image of Stenothoe lowryi Azman, 2023, female, ZSI/EBRC/Cr-18901.

Figure 1

Figure 2. Stenothoe lowryi, male, ZSI/EBRC/Cr18899, Scale bar: 0.1mm).

Figure 2

Figure 3. Pereopod 3-7 and Uropod 1-3 of Stenothoe lowryi, male, ZSI/EBRC/Cr18899, Telson of female, ZSI/EBRC/Cr-18901. Scale bars: P3–P7 = 0.1mm; U1–U3 and T = 0.05mm.