Xyrias anjaalai, Augustina & Sreeram & Sukumaran & Jose & Sreekumar, 2020

Augustina, Treasa, Sreeram, Miriam Paul, Sukumaran, Sandhya, Jose, Anjaly & Sreekumar, K. M., 2020, A new deep-water species of snake eel, Xyrias anjaalai sp. nov. (Anguilliformes Ophichthidae), from the Western Indian Ocean, Zootaxa 4822 (4), pp. 577-587 : 579-581

publication ID	https://doi.org/ 10.11646/zootaxa.4822.4.7
publication LSID	lsid:zoobank.org:pub:87D2DD51-9795-4EED-A9AA-315AF33B1166
DOI	https://doi.org/10.5281/zenodo.4451253
persistent identifier	https://treatment.plazi.org/id/ADD8FEB0-68CE-444D-9135-A0A6B4F09F40
taxon LSID	lsid:zoobank.org:act:ADD8FEB0-68CE-444D-9135-A0A6B4F09F40
treatment provided by	Plazi
scientific name	Xyrias anjaalai
status	sp. nov.

Treatment

Xyrias anjaalai sp. nov.

(Common name in Indian languages Tamil and Malayalam: Anjaalai)

Common name in English: Kollam snake eel (Kollam is the geographical area from which the specimens were collected).

( Figs 1 View FIGURE 1 , 2 View FIGURE 2 , 3 View FIGURE 3 , 4 View FIGURE 4 Tables 1, 2)

Holotype. CMFRI.DNRNo.GB. 4.13.27.1, 640 mm in TL, female, Kollam , Kerala, India, 8 ° 50 ΄ 5 ΄΄ N, 75 ° 44 ΄ 5 ΄΄ E, on sand, ~ 290 m, deep-sea bottom trawl, Jose Antony, 16 November 2019.

Paratypes. CMFRI.DNRNo.GB.4.13.27.2, 595 mm in TL, female ; CMFRI.DNRNo.GB.4.13.27.3, 578 mm in TL, female, CMFRI.DNRNo.GB.4.13.27.5, 625 mm in TL, female; CMFRI.DNRNo.GB.4.13.27.6, 615 mm in TL, female; CMFRI.DNRNo.GB.4.13.27.7, 630 mm in TL, female; CMFRI.DNRNo.GB.4.13.27.8, 745 mm in TL, female; CMFRI.DNRNo.GB.4.13.27.9, 900 mm in TL, female; CMFRI.DNRNo.GB.4.13.27.10, 680 mm in TL, female; CMFRI.DNRNo.GB.4.13.27.11, 425 mm in TL, male; CMFRI.DNRNo.GB.4.13.27.12, 555 mm in TL, female, Kollam , Kerala, India, 8 ° 50 ΄ 5 ΄΄ N, 75 ° 44 ΄ 5 ΄΄ E, on sand slope, ~ 290 m, deep-sea bottom trawl, Jose Antony, 16 November 2019 ; CMFRI.DNRNo.GB.4.13.27.4, 565 mm in TL, male, Kollam , Kerala, India, 8 ° 41΄6΄΄N, 75 ° 38΄8΄΄E, on sand slope, ~ 347 m, deep-sea bottom trawl, Jose Antony, 11 October 2019 .

Diagnosis. A medium-sized species of Xyrias with head 10.5–12.1% and tail 41.2–47.2% of TL. Pectoral fin 3.7–4.5 in HL. Upper jaw elongated, 1.8–2.3 in HL. Snout short, 3.0– 3.7 in upper jaw length. Eyes moderate in size and not elevated, with a diameter of 1.4–2.0 in snout length. Irregular tooth patch of approximately six rows present in 1/10 th of lateral side of dental arch, in level with 9 th or 10 th vomerine teeth. Colouration when fresh and preserved: brown with numerous dark brown spots throughout the dorsal side of the body and pale ventrally. Mean Vertebral Formula 20/74/148, total vertebrae 147–149.

Description. Body nearly cylindrical with head and trunk longer than tail; depth at gill openings 32.3–38.5 in TL, tail 2.1–2.4, and head 8.2–9.5 in TL. Snout reduced, inclined from tip to eye. Jaws elongate, upper jaw slightly protruding over lower jaw. Middle of eye at front 32–38% of upper jaw. Short tubular anterior nostrils in upper jaw oriented laterally, with presence of a minute flap. Posterior nostril succeeds anterior nostrils, opens into mouth along outer edge of upper jaw and covered by a flap extending up to anterior margin of eye. Interorbital space flat, narrow and slightly wider than eye diameter; head flat, absence of brow at intersection of uppermost postorbital bone and frontal bone. Median fins difficult to observe in preserved specimens, ending before tail tip. Dorsal-fin origin nearly double of pectoral fin length behind its tips. Pectoral fins elongated, slightly wedge-shaped, and greater than distance from snout tip to rear margin of orbit. Pectoral fin base forming an acute angle of ~ 25 ° relative to body; anterior region of pectoral fin base laterally connected to posterodistal corner of gill opening on lower half of body.

Head pores small, those of mandible and preopercle conspicuous. Supraorbital pores 1+4, infraorbital pores 4+2, mandibular pores 5, supratemporal pores 2, and a single frontal pore, lateral-line pores before GO 7–10, lateralline pores before dorsal fin 17–22, lateral-line pores before anal fin 70–78, and preopercular pores absent ( Fig. 3 View FIGURE 3 ).

Teeth needle-like and conical, slightly recurved. In maxilla, anteriorly a pair of fang-like teeth with two pairs of smaller teeth preceding. Dentition on maxilla consisting of an outer series of close-set, curved uniserial teeth, oriented posteriorly. Inner series consisting of multiple rows, with a single row of teeth up to level of 3 rd vomerine tooth, a second row beginning from level of 3 rd vomerine tooth, a 3 rd row beginning at level of 4 th vomerine tooth between two existing rows, and posterior portion of teeth irregularly in six rows. Vomerine teeth uniserial (6–10); 1 st, 6 th, 8 th, 9 th and 10 th smaller in size, and 2 nd, 3 rd, 4 th, 5 th and 7 th larger. In two paratypes, 4 th vomerine tooth comparatively small in size. In two paratype vomerine tooth missing; sockets visible under microscope. Mandibular teeth uniserial. Anterior symphysis of mandible lacking teeth. Second and fourth teeth prominently larger than others, arranged as pairs with another side ( Fig. 4 View FIGURE 4 ).

Colouration pale on ventral surface and pale brown with dark brown spots on dorsal surface above lateral midline. Presence of closely packed dark brown spots near head region. Black spots on lower jaw, even after preservation. Two black patches on either side of pupil and orangish-red dorsal fin, distinguishable only in fresh specimens. Pectoral fins pale brown with numerous dark spots towards pectoral-fin base. Anal fins pale brown in preserved and fresh specimens, presence of red colouration in anal region observed in fresh specimens. Peritoneum pale ( Fig. 1 View FIGURE 1 ).

Distribution: Only known from off Kollam, Kerala, India.

Etymology: The species is named anjaalai in reference to the common name of the eel anjaalai which is used among Malayalam and Tamil-speaking local fishing communities in the southern parts of Kerala and Tamil Nadu states of India.

Molecular data. Among the four previously described species of Xyrias genus, only sequences of X. revulsus are available. To this group, the present study adds the DNA sequences of X. anjaalai which will serve for rapid identification of the species in future.

The phylogenetic tree was constructed using 45 sequences of CO1 gene from 16 different species belonging to the subfamily Ophichthinae ( Fig. 5 View FIGURE 5 ). Xyrias revulsus and X. anjaalai showed distinct clustering among species with significant posterior probabilities. The genetic divergence among the species of the Ophichthinae ranges from 0.6% to 24.0% with an overall mean genetic divergence 18.0%. Within-group mean Kimura 2P distance of X. anjaalai and X. revulsus is 0.2 and 0.0% respectively. Kimura 2P distance percentage values ( Table 3) between species showed the new species is closest to X. revulsus (0.6%) followed by Apterichtus klazingai (Weber, 1913) (2.8%).