Nettenchelys gephyra Castle & Smith 1981

Smith, David G., Lin, James, Chen, Hong-Ming & Pogonoski, John J., 2015, The eels of the genus Nettenchelys, with description of a new species from Taiwan (Teleostei: Anguilliformes: Nettastomatidae), Zootaxa 4060 (1), pp. 105-120 : 110-113

Nettenchelys gephyra Castle & Smith 1981

Figs. 1 b, 3, 4; Table 2

Nettenchelys gephyra Castle & Smith in Smith et al. 1981:553, figs. 8–11. Holotype. MNHN 1979–0150 ( New Caledonia). Gloerfelt-Tarp & Kailola, 1984:60 –61, 305 ( Indonesia); Last et al., 2014:208 ( Australia).

Material examined. Taiwan: ASIZP 0 0 63132 (1, 398 mm, mature female, egg size 1.0 mm), Daxi, Yilan, Taiwan, bottom trawl, 24˚48’36”N, 122˚7’48”E, depth 600 m, 27 April 2004. TOU-AE 6529 (1, 456 mm, mature female, egg size 1.0 mm), Daxi, Yilan, Taiwan, bottom trawl, 24˚48’36”N, 122˚7’48”E, depth 400 m, 19 July 2012; TOU- AE 6547 (1, 363 mm, mature female, egg size 1.0 mm), Daxi, Yilan, Taiwan, bottom trawl, 24˚48’36”N, 122˚7’48”E, depth 400 m, 25 July 2012. Indonesia: AMS I.22852-001 (1, 207 mm), Indonesia, Sumbawa, Saleh Bay, 08°27’S, 117°47’E, July 1981. AMS I.24306-001 (1, 366 mm), same locality and date, 180– 300 m. Australia: AMS I.25834-002 (1, 275 mm), Australia, Queensland, 18° 01’S, 147°07’E, 300 m, 19 January 1986. CSIRO H 1106-05 (1, 240 mm), Australia, Queensland, 18° 01’ S, 147° 01’ E, 208–212 m, 29 November 1985. CSIRO H 1556-04 (2, 282– 302 mm), Australia, Queensland, 22° 57’ S, 153° 01’ E, 325–338 m, 18 November 1985. CSIRO H 1668-02 (1, 283 mm), Australia, Queensland, 22° 57’ S, 153° 01’ E, 345–350 m, 17 November 1985. NTM S 11779.007 (1, 170 mm), Australia, Queensland, 18°00’S, 147°04’E, 260 m, 19 January 1986. Other material. Holotype: MNHN 1979-0150 (female, 431 mm), New Caledonia.

Diagnosis. Anteriormost vomerine teeth uniserial and enlarged; posterior nostril on top of head approximately midway between eye and supratemporal canal; median ST pore present; 79–101 PCV. See Table 1 for additional characters.

Description. Measurements as percent of preanal length: predorsal 27.9–39.8, head 24.8–37.6; as percent of head length: snout 33.0–42.4, eye 7.4–11.3, upper jaw 48.3–57.6, lower jaw 47.3–52.9, interorbital 3.4–7.6. TV 202+, PDV 5–8, PAV 42–ca. 47, PCV 79–101, PADR ca. 72–112, PALL 39–51, PDLL 7–8, IO 8–9 + 3–4, SO 5, POM 11–15, ST 3.

Head and snout elongate, slightly depressed, snout flexible. Anterior nostril tubular, near tip of snout; posterior nostril on top of head, about midway between posterior margin of eye and supratemporal canal. Origin of dorsal fin slightly behind gill opening. Anus before midbody. Intermaxillary teeth in a short patch, about as long as wide, continuous with maxillary teeth. Maxillary and dentary teeth in bands, the inner teeth larger than outer. Vomerine tooth patch elongate, extending from slightly behind level of anterior nostrils to anterior margin of eye, consisting of a short median row of enlarged teeth at anterior end, followed by a narrow band of smaller teeth, the middle ones slightly enlarged.

Color in fresh specimens pink to dark purple or brown; snout and dorsal body dark purple to brown; abdominal region pink and pale; behind eye, occipital region, and around gill opening pink to purple; at midbody, myomeres become obvious, with darkish color. Dorsal and anal fins dark-edged, both becoming black posteriorly. In alcohol, light to dark brown dorsally, and pale below.

Distribution. New Caledonia, Australia, Indonesia, and Taiwan.

Remarks. Considerable variation occurs in this species over its range. This is particularly evident in the preanal lateral-line pores, maxillary pores, preanal vertebrae, precaudal vertebrae, and preanal dorsal rays ( Table 2 ). The posterior nostril appears slightly closer to the eye in the Australian specimens than in the Taiwan specimens, although not nearly as close as in N. proxima . We hesitate to describe these variants as species based on such a small sample size and without any genetic information. We simply note the differences and leave the nomenclatural decisions to future studies when more information is available.

The typical IO pore count for this species is 9 + 3. One specimen from Australia had eight pores along the upper jaw, and another Australian specimen had an extra pore behind the eye on one side.

We also note an inconsistency in the number of POM pores reported by Smith et al. (1981:553 and fig. 11). The text states 17 POM pores, but the figure shows 13 (11+2). We suspect that the latter figure is correct. Smith et al. (1981) did not give vertebral counts for the holotype, but a radiograph of this specimen is available online (http:/ /science.mnhn.fr/institution/mnhn/collection/ic/item/search/form). This image is divided into two parts, anterior and posterior. Assuming that there is no overlap or duplication in these two parts, we obtained the following counts: PDV ca. 8, PAV ca. 47, PCV ca. 92, TV 160+.

Figures

FIGURE 1. Position of the posterior nostrils in nine species of the genus Nettenchelys (modified after Karmovskaya, 1999). (a) N. pygmaea, N. proxima; (b) N. gephyra and N. dionisi; (c) N. inion; (d) N. paxtoni; (e) N. exoria; (f) N. erroriensis; and (g) N. taylori.

Tables

TABLE 2. Geographic variation in five characters in Nettenchelys gephyra

	PALL	Max pores	PCV	PAV	PADR
Taiwan	ca 46–51	8	91–101	45	102–112
Indonesia	39–41	9	79–80	42	ca 72–ca 79
Australia	42–c 46	8–9	85–92	42–45	ca 85–ca 95
New Caledonia	44	9	ca 92	ca 47	--