Pisodonophis sangjuensis, Ji, Hwan-Sung & Kim, Jin-Koo, 2011

Ji, Hwan-Sung & Kim, Jin-Koo, 2011, A new species of snake eel, Pisodonophis sangjuensis (Anguilliformes: Ophichthidae) from Korea, Zootaxa 2758, pp. 57-68 : 59-66

Pisodonophis sangjuensis sp. nov.

(New English name: Korean Snake eel, New Korean Name: Sang-ju-mul-baem) ( Figs 2–4 )

Holotype. PKU 3693, 601 mm TL, female, Sangju, South Sea of Korea (N 34°37ʹ0 4ʺ, E 128°06ʹ18ʺ), caught by trawl at 40 m, 5 June, 2010.

Paratypes. PKU 840, 502 mm TL, female, South Sea of Korea (N 33°44ʹ0 7ʺ, E 128°21ʹ43ʺ), caught by trawl at 100 m, 25 Sep., 2008; PKU 3483–PKU 3484, 395– 431 mm TL, male, South Sea of Korea (N 34°56ʹ0 0ʺ, E 127°47ʹ0 1ʺ), caught by set net at 2 m, 27 Nov., 2009; PKU 3864, 532 mm TL, female, South Sea of Korea (N 33°00ʹ37ʺ, E 127°04ʹ19ʺ), caught by trawl at 90 m, 4 Apr., 2005; PKU 3865–PKU 3872, 336– 495 mm TL, South Sea of Korea (N 34°20ʹ30ʺ, E 127°43ʹ19ʺ), caught by trawl at 60 m, 8 Nov., 2005; PKU 3873, 373 mm TL, male, South Sea of Korea (N 33°01ʹ23ʺ, E 125°46ʹ17ʺ), caught by trawl at 100 m, 17 Apr., 2006; PKU 3874–PKU 3876, 460– 521 mm TL, male, South Sea of Korea (N 34°16ʹ29ʺ, E 127°52ʹ21ʺ), caught by trawl at 50 m, 14 Jun., 2006; PKU 3877, 490 mm TL, female, South Sea of Korea (N 32°16ʹ13ʺ, E 125°57ʹ15ʺ), caught by trawl at 105–110 m, 29 Apr., 2007; PKU 3878–PKU 3879, 450– 625 mm TL, South Sea of Korea (N 34°48ʹ53ʺ, E 128°26ʹ46ʺ), caught by trawl at 50 m, 22 Jun., 2007; PKU 3880, 448 mm TL, male, South Sea of Korea (N 34°36ʹ0 2ʺ, E 128°15ʹ24ʺ), caught by trawl at 30 m, 8 Sep., 2007; PKU 4213, 595 mm TL, female, South Sea of Korea (N 34°37ʹ0 4ʺ, E 128°06ʹ18ʺ), caught by trawl at 40 m, 4 Sep., 2010.

Diagnosis. Dorsal-fin origin above the middle of the pectoral fin; pectoral fin rounded, not elongated, 2.6–3.5 times in head length (HL); snout slightly acute, 4.9–6.5 times in HL; upper jaw slightly longer than lower jaw, 3.4– 3.7 times in HL; fleshy protrusions before and behind the posterior nostril. Cephalic-sensory pores minute and inconspicuous; supraorbital pores 1+4, infraorbital pores 4+2, preoperculomandibular pores 3+5, supratemporal pores 1+4. Teeth conical, pointed, regular single row on both jaws, two regular rows anteriorly but 2–3 irregular rows posteriorly on vomer. Prevomerine and vomerine teeth are slightly separated from each other. Mean vertebral formula 14/50/147: 13–14 before the dorsal fin, 48–51 before the anal fin, and 143–153 in total.

Counts and measurements (in mm) of the holotype. Total length 601.0; head 55.3; trunk 161.6; tail 384.0; predorsal distance 64.3; pectoral fin length 19.3; pectoral fin base 6.3; body depth at gill openings 18.6; body width at gill openings 2.7; body depth at anus 20.6; body width at anus 18.3; snout 9.5; tip of snout to rictus 16.6; tip of lower jaw to rictus 12.8; eye diameter 4.9; interorbital distance 8.2; gill opening height 5.3; isthmus width 11.9; 13 predorsal vertebrae/50 preanal vertebrae/153 total vertebrae.

Description. Body elongate and cylindrical, and slightly tapering toward the tail ( Fig. 2 ). Caudal fin absent. Body depth at gill opening 30.3–37.0 times in TL. Head+trunk 2.6–2.7 times in TL; head length 10.1–10.8 times in TL and 2.8–2.9 times in trunk (Table 2). Snout slightly acute. Upper jaw slightly longer than lower jaw. Eye diameter 2.8–3.6 times in upper jaw length and 8.8–12.3 times in HL. Anterior nostrils tubular, on lateral surface of the upper lip. Posterior nostrils at the edge of upper lip, covered by a flap. Upper lip with fleshy protrusions before and behind the posterior nostril. Dorsal-fin origin above the middle of the pectoral fin. Pectoral fin rounded, not elongated, about 2.6–3.5 times in HL. Pectoral-fin base 7.5–10.2 times in HL. Pectoral-fin rays 12-14. Vertebrae: 13–14 before the dorsal fin, 48–51 before the anal fin, and 143–153 in total. Cephalic-sensory pores ( Fig. 3 ) minute, inconspicuous. Supraorbital pores 1+4, infraorbital pores 4+2, mandibular pores 5, preopercular pores 3, supratemporal pores 1+4. Lateral-line pores minute; 10 before gill opening, 51–54 before mid-anus. Teeth ( Fig. 4 ) small, conical, pointed. Prevomerine teeth large, one central and one row on each side. Vomerine teeth biserial, two regular rows of 21–24 teeth anteriorly, followed by 2–3 irregular rows of 11–13 teeth posteriorly. Maxillary teeth in a single row of 25–28 teeth. Mandibular teeth 1–2 rows anteriorly, followed by a single row of 30–33 teeth. Prevomerine and vomerine are slightly separated from each other.

A total of 983 base pairs of the mitochondrial DNA 12S rRNA sequence of Pisodonophis sangjuensis were compared with those of six ophichthid species and two outgroups ( Anguilla japonica and Conger myriaster ). Kimura’s genetic distance was large between P. sangjuensis and P. cancrivorus (0.068), although they are congeneric species, followed by the distance to Ophichthus serpentinus (0.080; Table 4). The Maximum-likelihood tree shows the reciprocal monophyly of P. sangjuensis , being supported by high bootstrap values (100; Fig. 5 ).

Color when fresh ( Fig. 2 ): body uniform dark brownish dorsally, but head and body pale brownish ventrally. Dorsal, anal, and pectoral fins blackish red.

Color in formalin: body uniform dark blackish dorsally, head and body pale whitish ventrally. Dorsal, anal, and pectoral fins whitish.

Size. The largest specimen is 601 mm TL, a mature female.

Etymology. The specific name, sangjuensis , refers to the name of type locality (Sangju).

Distribution. South Sea of Korea, 5–110 m depth.

Remarks. The genus Pisodonophis contains seven species worldwide ( Eschmeyer, 2010), six of which ( Pisodonophis cancrivorus , Pisodonophis boro , Pisodonophis copelandi , Pisodonophis hijala , Pisodonophis hoevenii , and Pisodonophis hypselopterus ) are from East Asia, and Pisodonophis daspilotus is from the eastern Pacific ( Fig. 6 ) ( Eschmeyer, 2010; McCosker, 2011). The genus Pisodonophis has not been reviewed taxonomically except for some brief descriptions ( McCosker, 1977, 1989; Smith and McCosker, 1999). The six species ( Ophisurus cancrivorus , Ophisurus hoevenii , Ophisurus hypselopterus , Ophisurus boro , Ophisurus hijala , Ophisurus semicinctus ) previously included in the genus Ophisurus were relocated to the genus Pisodonophis according to its characteristic of having granular and conical teeth ( Jordan and Richardson, 1910; Herre, 1923; Smith, 1962). Ophisurus semicinctus has been shown to require a new genus ( McCosker, 2011). Three species, Pisodonophis daspilotus , Pisodonophis zophistius , Pisodonophis copelandi were described as Pisodonophis , however P. z o p h i s t i u s has been found to be a synonym of Ophichthus altipennis ( McCosker, 2011) . In recent years, Smith and McCosker (1999) defined the genus Ophisurus as having canine teeth, the genus Ophichthus as having conical teeth, and the genus Pisodonophis as having granular or conical teeth in both jaws. We suggest that Pisodonophis requires a careful revision.

Pisodonophis sangjuensis is most similar to P. cancrivorus in its morphology and coloration, but the former differs from the latter in its teeth shape and distribution (conical teeth in P. sangjuensis vs. granular teeth in P. cancrivorus ) and its number of vertebrae (143–153 vs. 153–164, respectively) ( McCosker & Castle, 1986; Hatooka, 2002; Lee, 2009) (Tables 2, 3). Pisodonophis sangjuensis differs from P. boro in the origin of the dorsal fin (above the middle of the pectoral fin in P. sangjuensis vs. far behind the pectoral fin tip in P. boro ) ( Table 3), its number of vertebrae (143–153 vs. 170–177, respectively), its teeth shape (conical vs. granular, respectively) and habitat (marine vs. fresh or brackish waters, respectively) ( Herre, 1923; McCosker et al., 1989; Hatooka, 2002). Pisodonophis sangjuensis differs from P. copelandi in the origin of the dorsal fin (above the middle of the pectoral fin in P. sangjuensis vs. far behind the pectoral fin tip in P. copelandi ), its teeth rows on both jaws (1 row vs. 2 rows, respectively) ( Herre, 1953) ( Table 3). Pisodonophis sangjuensis differs from P. hypselopterus in its number of vertebrae (143–153 in P. sangjuensis vs. 120 in P. hypselopterus ), the number of pectoral fin rays (12–14 in P. sangjuensis vs. 17 in P. hypselopterus ), its teeth shape (conical vs. granular, respectively) (Tables 2, 3), and habitat (marine vs. fresh or brackish waters, respectively). Pisodonophis sangjuensis differs from Pisodonophis hijala and Pisodonophis hoevenii in its number of pectoral fin rays (13 in P. sangjuensis vs. eight in P. hijala and 10 in P. hoevenii ) and in the origin of the dorsal fin (above the middle of the pectoral fin vs. behind pectoral fin vs. above the middle of the pectoral fin, respectively) ( Table 3). Pisodonophis sangjuensis is easily distinguished from Pisodonophis daspilotus in lacking bands and dark markings on its body (no markings in P. sangjuensis vs. central circular dark markings in P. daspilotus ) ( Fig. 7 ), and in the shape of its teeth (conical vs. blunt vs. granular, respectively) and in the origin of the dorsal fin (the middle of the pectoral fin vs. behind of pectoral fin vs. in front of pectoral fin, respectively) ( McCosker and Rosenblatt, 1995; Bilecenoglu et al., 2009) ( Table 3).

Dorsal fin origin Middle of pectoral fin Middle of pectoral fin Far behind of pectoral fin Far behind of pectoral fin

Dentition Uniserial Multiserial Multiserial Beserial

Teeth shape Conical Granular Granular Conical

Body color Dark brown Dark brown Brown Dusky brown (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

Pisodonophis sangjuensis sp. nov. (1)

Pisodonophis sangjuensis sp. nov. (2) 0.000

Pisodonophis sangjuensis sp. nov. (3) 0.000 0.000

Pisodonophis sangjuensis sp. nov. (4) 0.000 0.000 0.000

Pisodonophis cancrivorus (5) 0.068 0.068 0.068 0.068

Echelus urotperus (6) 0.114 0.114 0.114 0.114 0.109

Echelus myrus (7) 0.105 0.105 0.105 0.105 0.099 0.015 Ophichthus asakusae (8) 0.081 0.081 0.081 0.081 0.081 0.079 0.066 Ophichthus serpentinus (9) 0.080 0.080 0.080 0.080 0.087 0.077 0.070 0.057 Ophichthus zophochir (10) 0.089 0.089 0.089 0.089 0.085 0.085 0.078 0.066 0.048 Anguilla japonica (11) 0.201 0.201 0.201 0.201 0.186 0.155 0.160 0.170 0.169 0.164 Conger myriaster (12) 0.214 0.214 0.214 0.214 0.209 0.216 0.216 0.255 0.221 0.216 0.183

A molecular phylogenetic study of several Anguilliformes based on mtDNA 12S rRNA sequences showed high genetic distances among three ophichthid species ( Ophichthus evermanni , P. cancrivorus , and Xyrias revulsus ; 0.063–0.094; see Wang et al., 2002). From the perspective of the genetic distances reported by Wang et al. (2002), our new species must be the eighth species of the genus Pisodonophis . Most ophichthid species are known to live in waters relatively shallower than 100 m ( McCosker, 2010).

Comparative materials.

Pisodonophis cancrivorus , BMNH 1938.12.32.1 (618.0 mm TL), Singapore (N 1°14ʹ28ʺ, E 103°48ʹ0 7ʺ), no collection date; BMNH 1938.12.21.2 (735.0 mm TL), Philippines (N 14°39ʹ23ʺ, E 120°43ʹ0 1ʺ), no collection date; HUMZ-161 (652.0 mm TL), no collection locality or date; HUMZ-44598 (374.0 mm TL), Ogasawara Island, Japan (N 26°56ʹ0 9ʺ, E 142°13ʹ30ʺ), no collection date.

Ophichthus altipennis , HUMZ-58879 (846.0 mm TL), Japan (N 35°03ʹ11ʺ, E 139°43ʹ32ʺ), 6 Nov., 1976; HUMZ-171743 (532.0 mm TL), Japan (N 33°24ʹ53ʺ, E 133°21ʹ0 5ʺ), caught by trawl, July, 1995; HUMZ-171744 (581.0 mm TL), Japan (N 33°24ʹ53ʺ, E 133°21ʹ0 5ʺ), caught by trawl, July, 1995.

Pisodonophis boro , HUMZ-70754 (561.0 mm TL), Hainan Island, China (N 18°57ʹ28ʺ, E 108°22ʹ35ʺ), Sep., 1939.

Pisodonophis copelandi , USNM 202516 (308.0 mm TL), Luzon Island (N 14°37ʹ51ʺ, E 120°53ʹ37ʺ), 21 Nov., 1947; USNM 202517 (303.0 mm TL), Luzon Island (N 14°37ʹ51ʺ, E 120°53ʹ37ʺ), 21 Nov., 1947.

Pisodonophis hypselopterus , BMNH 1867.11.28.279 (313.0 mm TL), no collection locality or date.

Pisodonophis hoevenii , BMNH 1867.11.28.314 (623.0 mm TL), no collection locality or date.

Pisodonophis daspilotus , USNM 318297 (413.0 mm TL), Panama (N 08°00ʹ0 6ʺ, E 80°24ʹ31ʺ), 22 Mar., 1990.

“ Pisodonophis ” semicinctus , BMNH 1845.2.11.39 (687.0 mm TL), no collection locality or date; BMNH 1852.8.12.43 (725.0 mm TL), no collection locality or date; BMNH 1853.1.11.9 (538.0 mm TL), no collection locality or date; BMNH 1865.1.23.3 (747.0 mm TL), no collection locality or date.

Ophichthus evermanni , ASIZ0060063 (738.0 mm TL), Taiwan (N 24°57ʹ0 0ʺ, E 121°52ʹ48ʺ), 1 May, 1993; ASIZ006315 (434.0 mm TL), Taiwan (N 24°57ʹ0 0ʺ, E 121°52ʹ48ʺ), 18 May, 1999; ASIZ0060864 (725.0 mm TL), Taiwan (N 22°27ʹ45ʺ, E 120°28ʹ13ʺ), 10 May, 2000.

Ophichthus rotundus , BKNU 3001 (793.0 mm TL), Yellow Sea (N 35°48ʹ35ʺ, E 126°36ʹ28ʹ), 27 June, 1993; BKNU 916–925 (605.0–722.0 mm TL), Yellow Sea (N 35°48ʹ35ʺ, E 126°36ʹ28ʺ), 8 Sep., 1995.

Muraenichthys gymnopterus , FSIU 2144 (254.6 mm TL), Yellow Sea (N 37°23ʹ, E 126°44ʹ), 24 June, 2007.

Figures

FIGURE 2. Holotype of Pisodonophis sangjuensis, PKU 3693, 601 mm, from Sangju, Korea.

FIGURE 3. A: Head of holotype of Pisodonophis sangjuensis, showing lateral cephalic sensory pores; B. Head of holotype of Pisodonophis sangjuensis, showing the dorsal cephalic sensory pores. Abbreviations: SO, supraorbial pores; IO, infraorbital pores; POM, preopercular and mandibular pores; ST, supratemporal pores; LL, lateral line pores.

FIGURE 4. Dentition of holotype of Pisodonophis sangjuensis. Abbreviations: PV, prevomer; V, vomer; MX, maxillary; MD, mandibular.

FIGURE 5. Maximum likelihood tree based on partial 12 S rRNA nucleotide sequences showing the relationship among seven ophichthid fishes and two outgroups. Bootstrap values 1000 replications are shown. Bar indicates genetic distance of 0.05.

FIGURE 6. Map showing the distribution area of Pisodonophis sangjuensis (●), Pisodonophis cancrivorus (Richardson, 1848) (Ο), Pisodonophis boro (Hamilton, 1822) (), Pisodonophis copelandi Herre, 1953 (․), Pisodonophis daspilotus Gilbert, 1898 (□), Pisodonophis hijala (Hamilton, 1822) (), Pisodonophis hoeveni (Bleeker, 1853) () and Pisodonophis hypselopterus (Bleeker, 1851) ().

FIGURE 7. A: Syntype of Ophisurus cancrivorus, BMNH 1838.12. 21.1, 618.0 mm from England. B: Holotype of Pisodonophis copelandi, USNM 202516, 308.0 mm from USA. C: Holotype of Pisodonophis hypselopterus, BMNH 1867.11. 28.279, 313.0 mm from England. D: Holotype of Pisodonophis hoevenii, BMNH 1867.11. 28.314, 623.0 mm from England. E: Pisodonophis daspilotus, USNM 318297, 413.0 mm from USA.