Ariosoma indicum sp. nov., a new species of congrid eel (Anguilliformes: Congridae: Bathymyrinae) from the Indian waters

Abstract

Ariosoma indicum sp. nov. is described herein based on 12 specimens [(335–433 mm total length (TL)] collected off the Arabian Sea of southwest coast of India and 7 specimens from Digha Mohana, off the Bay of Bengal of northeast coast of India. The new species is distinguished from congeners in having the following combination of the characters: anus positioned anterior to middle of total length, pre‐anal length 40.0%–43.1% of TL; short wedge‐shaped pointed vomerine teeth patch, three or four rows in anterior portion, tapering posteriorly with four uniserial teeth; supraorbital canal with four or five pores; pre‐dorsal vertebrae 9–10; pre‐anal vertebrae 49–53; total vertebrae 141–146; body greenish‐brown in colour; extremities of the lower jaw with minute dark pigmentation patches before the rictus, bicoloured pectoral fin. A. indicum shares few characters with the Indian water species, Ariosoma gnanadossi, but readily differs from the latter in having more pre‐anal vertebrae (49–53 vs. 47 in A. gnanadossi); fewer lateral‐line pores (130–137 vs. 145); shorter tail (54.9%–57.9% TL vs. 60.1% TL); smaller eye (15.1%–17.7% HL vs. 19.2% HL); smaller interorbital width (11.8%–15.7% HL vs. 18.2% HL); longer upper jaw (26.9%–30.2% HL vs. 19.2% HL). In addition, molecular analysis using partial mitochondrial COI gene suggests that A. indicum is genetically closer to Ariosoma maurostigma and Ariosoma melanospilos with a divergence of 15.0% and 15.8%, respectively, and forms a well‐supported monophyletic clade.

Two new species of the congrid eel genus Ariosoma (Anguilliformes, Congridae, Bathymyrinae) from Indian waters

“…At present, 40 species of the genus Ariosoma were described (Fricke et al 2023 and this study), with at least 74% (31 species) of all species of this genus being described or identified from the Indo-West Pacific, seven species distributed along the Atlantic Ocean and two from the eastern Pacific Ocean (Smith and Kanazawa 1977;Karmovskaya 1991Karmovskaya , 2004Karmovskaya , 2015Karmovskaya , 2018Shen 1998;Smith et al 2018;Roy et al 2021;Kodeeswaran et al 2021Kodeeswaran et al , 2022aKodeeswaran et al , 2022bKodeeswaran et al , 2023Fricke et al 2023) and doubtlessly there will be many undescribed species to be discovered. Very few species of the genus Ariosoma exhibit an endemic distributional range like a specific locality or around several islands, for example, Ariosoma bauchotae Karrer, 1983 collected around western Madagascar (Smith 1989;Fricke et al 2018); Ariosoma emmae Smith & Ho, 2018, known only from Taiwan (Smith et al 2018); Ariosoma hemiaspidus (Wade, 1946), described from the Gulf of California, Mexico (McCosker and Rosenblatt 2010); Ariosoma mellissii (Günther, 1870), endemic to Saint Helena, southern-central Atlantic (Smith 2016); Ariosoma multivertebratum Karmovskaya, 2004, known only from Marquesas Islands (Karmovskaya 2004;Delrieu-Trottin et al 2015); Ariosoma sereti Karmovskaya, 2004, described only from Hiva Oa Island, Marquesas Islands (Karmovskaya 2004); and Ariosoma sazonovi Karmovskaya, 2004, collected and described only from the Philippines (Karmovskaya 2004); these species were known and described only from holotypes or with very few paratypes.…”

“…The new species shares similar vertebral counts with Ariosoma scheelei, a widely distributed species in Indo-West Pacific, but A. kannani can be easily distinguished from A. scheelei by having fewer POM pores (10 vs. 12 in A. scheelei) (Smith et al 2018) and shows 19.4% genetic differences. Further, A. kannani differs from all the Indian water congeners by having fewer total vertebrae (116-118 vs. 121-164 in others) and dorsal-fin origin behind pectoral-fin insertion (Kodeeswaran et al 2021(Kodeeswaran et al , 2022a(Kodeeswaran et al , 2022b(Kodeeswaran et al , 2023Ray et al 2022).…”

“…The genus Ariosoma along Indian waters was known only by two species till 2021 (Roy et al 2021). Then, extensive sampling efforts and integrative taxonomic approaches resulted in the description and documentation of an additional six species from the Indian waters (Roy et al 2021;Kodeeswaran et al 2021Kodeeswaran et al , 2022aKodeeswaran et al , 2022bKodeeswaran et al , 2023Ray et al 2022) and also Kodeeswaran et al (2021) mentioned the existence of a few more undescribed species along the Indian waters. Following sampling along the southern coasts of India, several specimens of an unknown congrid eel were encountered as trawl by-catch, with one unidentified specimen also being collected from the northern part of the Bay of Bengal.…”

A new species of the congrid eel genus Ariosoma (Teleostei: Anguilliformes: Congridae) from the Southeast coast of India, Bay of Bengal

“…(2021), Kodeeswaran et al . (2021, 2022a, 2022b, 2023) and Ray et al . (2022) which forms the ninth species of the conger eel genus Ariosoma known from the Indian waters.…”

“…Hitherto, eight species of the genus Ariosoma have been described or documented from the Indian waters, viz. Ariosoma albimaculatum Kodeeswaran et al ., 2023, Ariosoma anago (Temminck and Schlegel, 1846) (Mishra and Krishnan, 2003), Ariosoma bengalense Ray et al ., 2022, Ariosoma gnanadossi Talwar and Mukherjee, 1977, Ariosoma indicum Kodeeswaran et al ., 2022b, Ariosoma majus (Asano, 1958) (Roy et al ., 2021), Ariosoma maurostigma Kodeeswaran et al ., 2022a, Ariosoma melanospilos Kodeeswaran et al ., 2021. Among them, A. albimaculatum , A. bengalense , A .…”