A new congrid eel, Rhynchoconger randalli sp. nov. (Congridae: Anguilliformes) with a pentagonal pattern of vomer dentition from the Bay of Bengal, Indian waters Author Acharya, Smrutirekha 0000-0001-8990-8311 Estuarine Biology Regional Centre, Zoological Survey of India, Gopalpur-on-Sea, Ganjam, Odisha, India 761002 & Department of Marine Sciences, Berhampur University, Bhanja Bihar, Berhampur, Ganjam, Odisha, India 760007 smrutirekhalucy @ gmail. com; https: // orcid. org / 0000 - 0001 - 8990 - 8311 smrutirekhalucy@gmail.com Author Mohanty, Swarup Ranjan 0000-0002-0473-9166 Estuarine Biology Regional Centre, Zoological Survey of India, Gopalpur-on-Sea, Ganjam, Odisha, India 761002 & Environmental Science Laboratory, Department of Zoology, Ravenshaw University, Cuttack, Odisha, India 753003 mohantyswarup 93 @ gmail. com; https: // orcid. org / 0000 - 0002 - 0473 - 9116 mohantyswarup93@gmail.com Author Ray, Dipanjan Bajkul Milani Mahavidyalaya, Kismat Bajkul, Purba Medinipur, West Bengal, India 721655 Author Mishra, Subhrendu Sekhar 0000-0003-4672-8374 Estuarine Biology Regional Centre, Zoological Survey of India, Gopalpur-on-Sea, Ganjam, Odisha, India 761002 & subhrendumishra @ gmail. com; https: // orcid. org / 0000 - 0003 - 4672 - 8374 subhrendumishra@gmail.com Author Mohapatra, Anil Estuarine Biology Regional Centre, Zoological Survey of India, Gopalpur-on-Sea, Ganjam, Odisha, India 761002 text Zootaxa 2022 2022-08-09 5174 2 188 194 journal article 120307 10.11646/zootaxa.5174.2.5 123b08bd-89a7-4dc2-a7d0-aa3b4571224f 1175-5326 6990256 3FBF7288-48A1-44A0-BB7B-6CB391D237DC Rhynchoconger randalli sp. nov. Proposed common name: Randall’s conger eel ( Figures 1–4 , Table 1 ) Holotype . EBRC /ZSI/F13832 (596+ mm TL), Paradeep fish landing centre, Odisha , India , depth of capture: 36–40 m , date of collection: 3 Nov. 2021 Paratype . EBRC /ZSI/F13833, 1 (599+ mm TL), Paradeep fish landing centre, Odisha , India , depth of capture: 36–40 m , date of collection: 3 Nov. 2021 Diagnosis . A species of the genus Rhynchoconger clearly distinguished from other congeners in having the following combination of characters: distinct pentagonal vomerine tooth patch ( Figs. 3–4 ); posterior tip of vomer clearly ends with single tooth before anterior level of eye; vomerine tooth patch with 48–52 teeth in 8–9 rows; ethmovomerine tooth patch with 60–64 teeth in 7–8 rows; posterior margin of eye just before rictus; dorsal-fin origin slightly anterior to level of gill opening; predorsal vertebrae 7–8; preanal vertebrae 29–31; dorsal-fin rays before vent 44–47; peritoneum and stomach colour pale. Description. A long conger eel of the genus Rhynchoconger with reduced tail tip. Body compressed gradually towards tail ( Fig. 1 ). Dorsal-fin origin slightly anterior to level of gill opening. Posterior margin of eye just before rictus. Width and depth of body at gill opening comparatively larger than those at anus. Head comparatively shorter than trunk (92.63–93.68 % of trunk length). Preanal length (PAL) 3.25 times in TL. Eye diameter 7.73–8 in head length (HL). Snout length 4.63‒4.68 in HL. Elongated pectoral fin (13.66‒13.59% PAL; Table 1 ). Anterior nostril tubular on ventrolateral side of snout tip, posterior nostril oval in front of mid-eye. Upper jaw clearly extends beyond tip of lower jaw. Upper jaw with unique pentagon-shaped vomerine tooth patch with pointed posterior end. Ethmovomerine teeth remain uncovered when mouth closed. Ethmovomerine tooth patch broader than long, with 60–64 blunt and granular to conical teeth arranged in 7–8 irregular rows, vomerine tooth patch is longer than broad, with 38–52 teeth arranged in 8–9 rows. Vomer, ethmovomerine, and maxilla clearly separated by narrow space from each other. Jaw and vomerine teeth comparatively smaller than ethmovomerine teeth. Maxillary and mandibular teeth mostly conical and blunt, some granular, starting with 5–6 rows anteriorly and narrowing down to 1–2 rows posteriorly ( Figs. 3–4 ). Arrangements of head pores: 3 supraorbital pores, 2 pores present on anterior end of snout and comparatively larger 3 rd pore on dorsal side of anterior snout end; 5 infraorbital pores, 1 st pore present on posterior dorsal side end of anterior nostril, along upper half of upper lip, 2 nd –4 th pores visible on head, and 5 th pore behind rictus; no frontal pore; 7+3 preoperculo-mandibular pores, first two very small pores close to each other among 7 pores along lower jaw, located at end of underside of lower jaw, 6 th pore behind rictus, and 7 th pore situated next to rictal pore, 3 preopercular pores, all preopercular pores comparatively larger than mandibular pores ( Fig. 2 ). Lateral-line pores: 7 predorsal pores, 8 prepectoral pores; 29 (29–31) preanal pores; 125+ (not visible to count after 125) total lateral-line pores. Vertebrae: 8 predorsal vertebrae, 29–31 preanal vertebrae, 125+–136+ total vertebrae. TABLE 1. Morphometric and meristic comparison of Rhynchoconger randalli sp. nov. with Rhynchoconger smithi (data taken from Mohapatra et al ., 2022 ).

Rhynchoconger randalli sp. nov.		Rhynchoconger smithi
Holotype	Paratypes (n=1)	Paratypes (n=3)
TL (mm)	596+	599+	576+‒661+
PAL (mm)	183	184	172‒203
% TL
Preanal length	30.70	30.72	31.3‒32.6
Tail length	69.30	69.28	67.3‒68.6
Trunk length	15.94	15.86	16.8‒17.7
Predorsal length	13.93	14.02	13.1‒14.2
Head length	14.77	14.86	14.2‒15.8
Depth at gill opening	4.36	4.34	4.3‒6.2
Depth at anus	3.94	4.01	4.0‒6.0
% PAL
Trunk length	51.91	51.63	51.5‒56.6
Predorsal length	45.36	45.65	41.1‒46.3
Head length	48.09	48.37	45.8‒50.0
Depth at gill opening	14.21	14.13	14.5‒19.7
Depth at anus	12.84	13.04	13.5‒19.2
Snout length	10.38	10.33	9.4‒11.3
Eye diameter	6.01	6.25	4.4‒4.9
Interorbital width	6.28	6.52	7.2‒9.3
Upper jaw length	17.49	18.48	14.5‒16.7
Lower jaw length	13.66	14.13	11.4‒13.3
Pectoral fin length	13.66	13.59	11.9‒13.7
Gill opening width	6.56	7.07	4.9‒5.9
Interbranchial width	8.74	8.70	6.98–7.39
% HL
Snout length	21.59	21.35	18.8‒21.9
Eye diameter	12.50	12.92	9.5‒9.7
Interorbital width	13.07	13.48	15.0‒18.1
Upper jaw length	36.36	38.20	29.5‒32.3
Lower jaw length	28.41	29.21	24.3‒25.7
Pectoral fin length	28.41	28.09	25.6‒26.6
Gill opening width	13.64	14.61	10.2‒11.4
Interbranchial width	18.18	17.98	14.2‒15.9
Predorsal lateral-line pores (LLP)	7	7	7
Prepectoral LLP	8	8	9
Preanal LLP	29	31	33
Total LLP	117+	134+.	150+
Vertebrae
Predorsal	7	8	7
Preanal	29	31	33
Total	125+	136+.	162+
Dorsal fin rays before vent	44	47	54–58

FIGURE 1. Rhynchoconger randalli sp. nov. , holotype, EBRC/ZSI/F13832. FIGURE 2. Arrangement of sensory pores and anterior lateral-line pores of Rhynchoconger randalli sp. nov. , from holotype. FIGURE 3. Microscopic picture of teeth on upper jaw of Rhynchoconger randalli sp. nov. , from holotype. FIGURE 4. Schematic diagram of teeth on upper jaw of Rhynchoconger randalli sp. nov. , from holotype. Colour . When fresh, body slightly reddish brown dorsally and pale white ventrally with a silvery streak along the body near the lateral line. From posterior margin of eye to gill opening, a bright silvery patch is observed. The dorsal fin has a black margin from anterior part to posterior end, but the anterior one third portion of anal fin is pale in colour and the rest has a black margin. Pectoral fin pale. Peritoneum and stomach colour pale. After preservation, the basic pattern of colour remains same. The reddish brown colour turns to faint brown colour in preserved specimen. Distribution. Collected from the northern part of the Bay of Bengal, Paradeep, Odisha , India . Etymology. The new species is named in the honour of the renowned ichthyologist John Ernest Randall ( USA ), posthumously.