Eptatretus

Augustina, Treasa, Sreeram, Miriam Paul, Sukumaran, Sandhya & Jose, Anjaly, 2022, A new species of six-gilled hagfish (Myxinidae: Eptatretus) from the Lakshadweep Sea, Zootaxa 5162 (2), pp. 120-134 : 131-132

Indian Ocean Eptatretus species

Seven Eptatretus species have hitherto been recorded from the Indian Ocean, namely E. alastairi ; E. hexatrema ; E. longipinnis ; E.strahani McMillan & Wisner, 1984 ; E. octatrema Barnard, 1923 ; E. indrambaryai Wongratana, 1984 and E. gomoni Mincarone & Fernholm, 2010 ( Wongratana 1983; McMillan & Wisner 1984; Mincarone & Fernholm 2010; Mincarone 2017), along with the recently recorded Eptatretus sp. ‘INDIA’ ( Fernholm et al. 2017), whose validity as a separate species is hitherto undecided. A comparison of the morphological characters of E. wadgensis with these species clearly indicates its uniqueness. The only other Indian Ocean six-gilled species with a 3/3 multicusp pattern is E. alastairi , which differs from E. wadgensis by its number of total pores (83–88 vs. 67–69), total cusps (48–54 vs. 44–48) and ventral aorta branching at 5–6 th gill pouch (vs. 4th to 5th gill pouch). A dichotomous key to the Indian Ocean species is provided. Excluding E. longipinnis and Eptatretus sp. ‘INDIA’, no molecular data of other Indian Ocean species is currently available.

Knowledge of Indian hagfish species is hitherto very limited since they are not commercially important and occur infrequently in bycatch. Eptatretus wadgensis is currently recorded from ~ 250–300 m depth. Deep-sea fishing in India is presently restricted to ~ 500 m. This fishery is on the threshold of large-scale expansion in Indian waters. The scarce collection of hagfishes from fishery bycatch and scientific explorations will likely improve with focused study on the ecology, biology and molecular data for the Indian Ocean hagfish species and add to the current knowledge of diversity and systematics .

Key to species of Eptatretus from the Indian Ocean

1a. Seven pairs of gill pouches..................................................................... E. strahani

1b. Six or eight pairs of gill pouches......................................................................... 2

2a. Eight pairs of gill pouches.............................................................................. 3

2b. Six pairs of gill pouches............................................................................... 4 3a. Total dental cusps 50........................................................................... E. gomoni

3b. Total dental cusps less than 50........................................................................... 5

4a. Multicusp pattern 3/2.................................................................................. 6

4b. Multicusp pattern 3/3.................................................................................. 7

5a. Total slime pores 104–117..................................................................... E. octatrema

5b. Total slime pores 78–80.................................................................... E. indrambaryai

6a. Total dental cusps 44-49....................................................................... E. hexatrema

6b. Total dental cusps 30........................................................................ E. longipinnis

7a. Total slime pores 83–88........................................................................ E. alastairi

7b. Total slime pores 67–69............................................................... E. wadgensis sp. nov.