Introduction
Gobiidae is the second largest fish family which consists of 167 valid genera and 1416 valid species (Fricke et al., Reference Fricke, Eschmeyer and Fong2024). Gobiid fishes are mostly distributed in tropical to sub-tropical waters, the marine, brackish, and freshwater environments. The genus Tomiyamichthys Smith, 1956 consists of 21 valid species distinguished from the other genera of gobies by having one-third or more of the ventral part of the first-gill slit closed by a membrane; gill rakers on the outer surface of the first arch are rudimentary or comparatively small and an equal number of dorsal and anal ray, numerous scales and moderately narrow gill opening reaching to the ventral side of operculum (Hoese et al., Reference Hoese, Shibukawa and Johnson2016). Tomiyamichthys are generally found from the Red Sea through the Indian Ocean to the Western Pacific Ocean. Kosygin et al. (Reference Kosygin, Mohapatra, Bineesh, Sharma, Jadhav and Khynriam2024) prepared a checklist of the family Gobiidae from Indian waters and listed 259 species. Although records of the genus Tomiyamichthys are very limited from India. Tomiyamichthys russus (Cantor, Reference Cantor1849) commonly known as ocellated shrimp goby has been previously reported from the Andaman Islands (Praveenraj et al., Reference Praveenraj, Rajan, Sankar and Roy2017) and Tamil Nadu (Ramaiyan et al., Reference Ramaiyan, Purushotaman and Natarajan1987; Mogalekar et al., Reference Mogalekar, Canciyal, Patadia and Sudhan2018).
Material and methods
A single specimen of T. russus measuring 84 mm Total Length (TL) and 67 mm Standard Length (SL) was collected from a trawl bycatch at Royapuram Fishing Harbour (13°07′24.49′′ N; 80°17′52.20′′E), Chennai, Southeast coast of India (Figure 1) (study map generated from QGIS 3.22.3 software). The trawler was operated along the coast of Tamil Nadu at a depth range between 5 to 20 m. Based on the key identification characters and following standard taxonomic literature (Hoese et al., Reference Hoese, Shibukawa and Johnson2016), the specimen was identified as T. russus. The morphometric measurements were taken with a digital Vernier Calliper (VC) with an accuracy of 0.1 mm and measured values are also expressed as the proportions of the Standard Length (% of SL) based on the previously available standard taxonomic literature (Table 1) (Shibukawa et al., Reference Shibukawa, Suzuki, Senou and Yano2005; Praveenraj et al., Reference Praveenraj, Rajan, Sankar and Roy2017). The specimen was preserved using 10% formalin and stored at Tamil Nadu, Dr MGR, Fisheries College and Research Institute, Ponneri, Tamil Nadu, India.
Study map and distribution of ocellated shrimp goby, Tomiyamichthys russus (red dot-present study & blue dots-previous records around world).
Morphometric characteristics of ocellated shrimp goby, Tomiyamichthys russus collected from Chennai, Southeast coast of India
Results
A single female specimen of T. russus (Figure 2) was recorded from the Bay of Bengal, Southeast coast of India. The specimen had a Total Length (TL) of 84 mm, and the Standard Length (SL) was 67 mm long. Other measurements are presented in Table 1.
Ocellated shrimp goby, Tomiyamichthys russus from Chennai, Southeast coast of India.
Systematic position
Order: Gobiiformes
Family: Gobiidae Cuvier, 1816
Genus: Tomiyamichthys Smith, 1956
Species: T. russus (Cantor, Reference Cantor1849)
Synonymy
Gobius russus: Cantor, Reference Cantor1849: Pls. 1–14; Shibukawa et al., Reference Shibukawa, Suzuki, Senou and Yano2005: fig. 3.
Cryptocentrus russus: Ramaiyan et al., Reference Ramaiyan, Purushotaman and Natarajan1987: 14.
Cryptocentrus polypthalmus: Kuiter and Tonozuka, Reference Kuiter and Tonozuka2001.
Flabelliogobius sp. 2: Senou et al., Reference Senou, Suzuki, Shibukawa and Yano2004: 290.
Flabelliogobius russus: Shibukawa et al., Reference Shibukawa, Suzuki, Senou and Yano2005: 196–200, figs. 1B, 2C.
Tomiyamichthys russus: Hoese et al., Reference Hoese, Shibukawa and Johnson2016: figs. 6C, 7; Praveenraj et al., figs. 2, 3.
Description of the specimen
Head slightly compressed with head length 29.8% SL, body depth of 17.1% SL; snout rounded with snout length of 7.4% SL; eyes moderate with eye diameter 7.6% of SL; first dorsal fin consists of 6 dorsal spines, first dorsal fin base length is 22.2% SL followed by second dorsal fin base length with 30.8% SL, second dorsal fin consists of 1 spine with 10 branched soft rays; pectoral fin consists of 17 branched rays, pectoral fin length is 23.4% SL; pelvic fin consists of 1 spine then followed by 5 branched rays, pelvic fin length is 22% SL; caudal peduncle length is 15.6% SL, caudal peduncle depth is 10.8% SL with segmented caudal fin rays comprising of 9 + 8 rays with 7 + 6 branched rays, caudal fin length is 31.9% of SL; lateral scales 78; transverse scales from the first dorsal fin initial point running across the abdomen in downward manner; pre-maxilla consists of 6 interiorly curved conical teeth in outer row and smaller teeth in inner row; dentary with 4 rows of teeth and 12 large conical teeth in outer row (Figure 3A); presence of small nostril located anteriorly which is the anterior nostril underneath to posterior nostril which both lies closely on the upper jaw portion.
(A) Lateral view of head, (B) arrow indicates small orange spots and pale violet traces on operculum.
Colouration
The body of the fresh specimen is pale grey with continuous large various sizes of black to brownish blotches along the lateral region. Crosswise rows of small orange spots surrounded by minute dull black circles in the cheek and pre-dorsal region (Figure 3B), the posterior area of the gill membrane orange, and the operculum with pale violet traces. Colour of the dorsal fin spine membrane is pale grey with continuous burden-like dark-grey blotches at mid of the dorsal base, a bulbous black spot surrounded by a white ventral margin in the distal part of the dorsal spine membrane located between the 3rd and 5th dorsal fin spine. The distal boundary of the dorsal fin is orange, 2nd dorsal fin is greyish white, the distal half with orange spots, posterior end of the dorsal fin yellow bordered by violet. Pectoral fin is transparent, pelvic fin is greyish and tip black, the anal fin is light grey. The caudal fin is greyish-black with and orange mid-anterior region surrounded by a white margin followed by a yellow band radiating from the caudal peduncle, postero-dorsal part of the caudal fin with a yellow margin, and reddish orange sub-margin outlined by narrow violet colour.
Geographical distribution
India: Tamil Nadu (Ramaiyan et al., Reference Ramaiyan, Purushotaman and Natarajan1987), Andaman Islands (Praveenraj et al., Reference Praveenraj, Rajan, Sankar and Roy2017); Malaysia (Penang); Thailand (Songkhla, Ranong); Vietnam (Nha Trang); China (Guangdong); Indonesia (Java, Ulakan, Makassar); Philippines; Oceania (Papua New Guinea); Japan (Okinawa, Urauchi-gawa) (Praveenraj et al., Reference Praveenraj, Rajan, Sankar and Roy2017).
Remarks
The genus Tomiyamichthys is differentiated by the presence of mental fraenum; membrane covering the gill slit about ventral one-third or in the lower part; a longitudinal pattern sensory-papillae row just behind the lower-jaw symphysis; ctenoid scales in the posterior region (Shibukawa et al., Reference Shibukawa, Suzuki, Senou and Yano2005; Hoese et al., Reference Hoese, Shibukawa and Johnson2016). Ocellated shrimp goby, Tomiyamichthys russus is generally found at a depth range of 5 m but the present specimen was caught at a depth range between 5 and 20 m and the habitat of this species is still unknown (Froese and Pauly, Reference Froese and Pauly2022). Tomiyamichthys russus is more similar to T. levisquama in body form and fin ray counts, but it differs by the body scales being cycloid anteriorly and ctenoid posteriorly on the body (vs all body scales cycloid in T. levisquama), the first dorsal spine longest (vs third to fifth dorsal spine longest), and 74–95 scale rows on the body (vs 50–70) (Hoese et al., Reference Hoese, Shibukawa and Johnson2016). Morphometric measurements of T. levisquama and T. russus are quite similar but they can be differentiated by the higher dorsal fin in males of T. levisquama (Hoese et al., Reference Hoese, Shibukawa and Johnson2016). This is the third record of this species from the Indian coast. Further, an intensive survey is required along the Indian coast waters to clarify the exact Indian distribution of T. russus.
Conclusion
T. russus was recently reported from the Andaman Islands along with two records from peninsular India. This present study provides the details of morphological description and its distribution. This study further extends the known distributional range of ocellated shrimp goby, T. russus.
Data
The authors confirm that the data supporting the findings of this study are available within the article.
Acknowledgements
The authors would like to thank the fishers of Royapuram Fishing Harbour, Chennai for providing the specimen during sample collection. Further, the authors would like to thank two anonymous reviewers for their valuable comments and suggestions, which helped to improve the quality of the manuscript.
Author Contributions
B. Sureandiran: sample collection, preparation of the manuscript, software analysis, and image preparation. K. Karuppasamy: helped during sample collection, supervision of the study. G. Mahadevan: conceptualization and taxonomic advice. N. K. Suyani: review and editing of the manuscript.
Financial Support
The study not received fund from any external agency.
Conflict of Interest
None.
Ethical Standards
The authors declare that the work was carried out within local guidelines without causing damage to the environment.
