Ariosoma, SWAINSON, 1838

Smith, David G., Ho, Hsuan-Ching, Huang, Jian-Fu & Chang, Yong-Hsu, 2018, The congrid eel genus Ariosoma in Taiwan (Anguilliformes: Congridae), with description of a new species, Zootaxa 4454 (1), pp. 84-106 : 86

Key to species of Ariosoma in Taiwan

1A. Black spots and patches on head; body and fins with 10–14 large black cross marks.................. Ariosoma fasciatum

1B. Head and body without black spots or patches............................................................... 2

2A. No or one pore behind eye; no pores between eyes; no pores in supratemporal canal; two small black patches on posterior margin of eye................................................................................ Ariosoma meeki

2B. Three pores behind eye, two pores between eyes, three pores in supratemporal canal; no black patches on posterior margin of eye................................................................................................. 3

3A. Dorsal-fin origin behind or just above insertion of pectoral fin; total vertebrae 115–121............... Ariosoma megalops

3B. Dorsal-fin origin clearly before insertion of pectoral fin; total vertebrae more than 127............................... 4

4A. Clear black and white bands on head; vertical fins with broad black margin, snout relatively pointed.................... 5

4B. No (or only weakly defined) black and white bands on head; vertical fins with very thin black margin; snout relatively blunt. 7

5A. Preanal vertebrae 54–56; precaudal vertebrae 71–72; total vertebrae 143–144; preanal pores 53–57; total pores 136–140............................................................................................. Ariosoma anago

5B. Preanal vertebrae 47–55; precaudal vertebrae 59–65; total vertebrae 127–134; preanal pores 47–53; total pores 121–133.... 6

6A. Usually four whitish bars across head; pectoral fin large, its length 40.0–56.7% HL; preanal length 43.1–46.8% TL.......................................................................................... Ariosoma dolichopterum

6B. Usually one whitish bar across anterior margin of eye; pectoral fin small, its length 29.1–35.2% HL; preanal length 46.9–49.6% TL................................................................... Ariosoma emmae sp. nov.

7A. Preanal vertebrae 58–59; precaudal vertebrae 82–83; total vertebrae 161–162; preanal pores 59; total pores 151–158............................................................................................ Ariosoma shiroanago

7B. Preanal vertebrae 51–55; precaudal vertebrae 68–73; total vertebrae 140–149; preanal pores 50–55; total pores 132–147............................................................................................. Ariosoma majus