Apterichtus moseri, : Smith, 1994

Ho, Hsuan-Ching, Hibino, Yusuke & Huang, Jian-Fu, 2018, Note on rare snake eels (Anguilliformes: Ophichthidae) and additional data on three Neenchelys recently described from Taiwan, Zootaxa 4454 (1), pp. 200-214 : 205

Apterichtus moseri ( Jordan & Snyder, 1901)

Figure 3 ; Table 1

Sphagebranchus moseri Jordan & Snyder, 1901:864, fig. 14 (type locality Suruga Bay, off Numazu , Shizuoka Prefecture, Japan, holotype USNM 49729 ) .

Apterichtus moseri: Smith, 1994:36 . McCosker & Hibino, 2015:22 (review).

Specimens examined. NMMB-P 26648 , 509 mm TL, off Nan-fang-ao fishing port, Suao , Yilan, northeastern Taiwan, bottom trawl, 29 Jun. 2017, coll. J.- F. Huang. Non-types from Japan. Five specimen listed in McCosker & Hibino (2015) . SFNR 11043 , 420 mm TL, northern East China Sea .

Diagnosis. A species of Apterichtus with a slender and cylindrical body, its depth 53¯74 times in TL; anus at or slightly anterior to mid-trunk; 3 preopercular pores and 5 (rarely 6) pores in supratemporal canal; anterior margin of orbit above or slightly behind tip of lower law; head 14¯ 18 in TL, trunk 2.2¯ 2.5 in TL; tail 1.9¯ 2.1 in TL. Total vertebrae 141¯145, MVF 66-143. Anterior third of body grayish; face, cheek and gill openings with white patches; posterior two-thirds uniformly tan; whitish pores surrounded by dark brown or dark orange blotches on preopercular and supratemporal canals (McCosker & Hibino, 2015; present study).

Description of NMMB-P26648. Body very elongate, its depth at anus 65 times in TL; somewhat cylindrical with tail gradually compressed posteriorly; depth of body relatively uniform, tapering gradually to tail tip; depth of head deeper than that of body. Tail slender, anus slightly anterior to midpoint of the fish. All fins absent.

Head relatively small, its length 17.6 times in TL; dense small papillae on surfaces of snout, lips and lower jaw; snout very pointed anteriorly, flattened ventrally; tip of snout projecting far beyond lower jaw, its length 5.7 times in HL; dorsal surface of snout convex, gradually narrower anteriorly. Anterior nostril tubular with the opening directed downward; posterior nostril on upper lip, beneath anterior margin of eye, the opening directed ventrally, appearing in lateral aspect as a diagonal slit.

Lower jaw included, its tip slightly before anterior margin of eye, far behind anterior nostril. Rictus extends to about two eye diameters behind a vertical through posterior margin of pigmented eyeball (posterior margin of eye about above midpoint of rictus). Tongue not free, well attached to mouth floor. Gill openings narrow and slightly oblique, situated at ventral side of head, their anterior ends closer to each other than posterior ends.

Head pores small ( Fig. 3C ). Supraorbital pores 5, first pore at ventral side of snout, last pore at anterior half of interorbital space; infraorbital pores 6, 2 pores between anterior and posterior nostrils, 3 along the upper jaw behind posterior nostril, and 2 behind eye. Mandibular pores 5; preopercular pores 3; supratemporal pores 5; 1 frontal pore.

Teeth slender, pointed, tips directed posteriorly ( Fig. 3D ). Intermaxillary teeth 6, in 2 oblique row, well separated from that of vomer; vomerine teeth with single row of 3 teeth; maxillary and dentary teeth uniserial, each with 12̄14) teeth.

Lateral line nearly complete, pores small and inconspicuous, the canal extending to nearly tip of rear end. Cephalic lateral line pores 4 (plus 2 pores above gill opening), preanal pores 64, and total pores 139.

Preanal vertebrae 63, and total vertebrae 144.

Coloration. When fresh, anterior third mostly yellowish gray on purplish red background, posterior two-thirds purplish red with some light gray patches. When preserved, anterior third of body grayish, face and cheek with large irregular areas; posterior two-thirds yellowish gray.

Remarks. The 5 supratemporal pores, 3 preopercular pores and 144 total vertebrae will narrow down our specimen to two candidate species in the key (item 16) provided by McCosker & Hibino (2015): A. moseri and A. klazingai . Our specimen has 63 preanal vertebrae and tail 1.9 times in TL, both are somehow in-between these two species. However, the specimen has the rictus slightly before the eye and a smaller head (17.6 times in TL) which will refer our specimen to A. moseri .

As shown in Table 2, our specimen fit to the Japanese species well, except for there are only 3 teeth on vomer ( Fig. 3D ) and coloration is slightly vary. YH examined one more specimen collected from East China Sea (SFNR 11043) which also has 3 vomerine teeth.

Figures

FIGURE 3. Apterichtus moseri (Jordan & Snyder, 1901), NMMB-P26648, 509 mm TL. A. lateral view. B. close view of head. C. head pores, arrows indicate the median ST pore (left) and frontal pore (right). D. teeth on upper jaw (left) and lower jaw (right).