Apterichtus flavicaudus ( Snyder 1904 )

Hibino, Yusuke, 2015, A review of the finless snake eels of the genus Apterichtus (Anguilliformes: Ophichthidae), with the description of five new species, Zootaxa 3941 (1), pp. 49-78 : 60-61

Apterichtus flavicaudus ( Snyder 1904)

Figure 2 , Table 1

Sphagebranchus flavicaudus Snyder 1904:516 , Pl. 2, fig. 4 (type locality Auau Channel, between Mauai Island and Lanai Island, Hawaiian Islands, holotype USNM 50863).

Apterichtus flavicaudus: McCosker 1977:66 .

Diagnosis. An elongate species with: tail 2.1–2.2, head 17–21, and body depth 43–66 in total length; 3 preopercular pores and 3 pores in supratemporal canal; teeth conical, uniserial on jaws and vomer; 1–2 vomerine teeth; body coloration light tan with numerous minute brown to dark brown spots on head, body and tail, with a faint white slash angling behind eye to behind jaw corner; and MVF 77–158, total vertebrae 154–166 (n=20).

Size. The largest specimen examined is 570 mm.

Distribution. Known from between 7–293 m depth, captured using rotenone, trawls and dredges. Hawaii, Midway, possibly Australia, including Lord Howe island (McCosker et al. 2006) and the Seychelles.

Remarks. Snyder’s (1904:516) description is based on “the type, No. 50863, U.S. Nat. Mus., 367 mm. long” and 2 other specimens; Smith (1994:36) clarified the status of the holotype, the paratype, and the third non-type specimen. The holotype has 80–157 vertebrae. Snyder’s description of the coloration of the fresh specimens (paratype and non-type) is informative. He reported “in life it (the cotype) was pinkish anteriorly, the posterior third tinged with lemon yellow.” The non-type in life “was light orange, fading to lemon yellow posteriorly; a indistinct, light, median dorsal stripe extending from occiput to tip of tail; ventral surface slightly tinged with purple, the tint extending about twice the length of head beyond anal opening; side of head with two white spots, the anterior one just behind eyes, the posterior one indistinctly connected over the occiput with its fellow on opposite side.”

As mentioned in the remarks section of A. australis , that species is most similar to A. flavicaudus and may ultimately be determined to be conspecific. At this time we are unable to synonymize them with confidence and we will continue to recognize them both as valid.

A badly damaged specimen dredged off Seychelles (depth unknown) is possibly this species. It has 157 vertebrae. At this time we are unable to identify it with certainty. We have examined a color photograph of a specimen of Apterichtus collected by benthic sled off the Lord Howe shelf, Australia. Its yellow/orange cephalic coloration and white cheek patch is typical of A. flavicaudus . The status of that specimen is uncertain (M. Francis, in litt., 13 Apr. 2012). Hatooka (1995) reports A. flavicaudus from sandy bottoms of shallow coastal waters of the Izu Peninsula. Underwater photographs have been taken of A. flavicaudus in Japan. Suzuki et al. (2004:7) photographed the head of an eel protruding from the sand at 20 m off Hasama, Tateyama Bay. Hatooka (1995) recorded a specimen as A. flavicaudus from Sagami Bay which Hibino reidentified as A. australis (see previous section on A. australis ).

Material examined. 20 specimens, 99–366 mm, including USNM 50863, the holotype, 364 mm, Auau Channel, between Maui and Lanai; CAS 107509, the paratype, 245 mm, Hilo Bay, Hawaii; BPBM 9866, 2(310–330 mm), Oahu; BPBM 36782, 6(99–317 mm), Oahu; CAS 213864, 351 mm, Oahu; CAS 218801, 199 mm, Oahu; SIO 68–487, 366 mm, Midway; SIO 69–364, 3(255–300) mm, Hawaii; SIO 73–318, 358 mm, Hawaii; USNM 320113, 215 mm, Hawaii. Seychelles: SIO 63–150, ~ 245 mm (damaged specimen), 04°31’S, 54°30’E, depth not recorded.

Figures

FIGURE 2. Underwater photograph of living Apterichtus flavicaudus, taken by J. Randall at 15 m, Makua, O’ahu, Hawai’i.