Yirrkala misolensis ( Günther, 1872 )

Chiu, Yung-Chieh, Chen, Hong-Ming & Shao, Kwang-Tsao, 2022, Additional description on morphology of the Misol snake eel from Taiwan, with four verified barcodes of life sequences, Zootaxa 5189 (1), pp. 114-121 : 117-119

Yirrkala misolensis ( Günther, 1872)

Fig. 1A–B , Fig. 2 A–B

Ophichthys misolensis Günther, 1872: 426 (Type locality: Misol Island, Indonesia). McCosker, 1977: 69.

Yirrkala misolensis ( Günther, 1872) : Smith & McCosker, 1999: 1669; McCosker et al., 2006: 277; Bucol et al., 2010: 98; McCosker, 2011: 47; Chiu, 2014: 30; McCosker, 2014: 339; Ho et al., 2015: 177 ; Hibino et al., 2021: 22.

Material examined. ASIZP 0080303 (1 specimen, 383 mm TL) and ASIZP 0080574 (1 specimen, 411 mm TL), 7 May 2016 ; ASIZP 0080575 (1specimen, 512 mm TL), 5 July 2016 ; TOU-AE7866 (1 specimen, 351 mm TL with broken tail), 4 September 2020, off Ke-tzu-liao fish market. NMMB-P12003 (1 specimen, 486 mm TL, mature female), 4 Sep. 2010 ; NMMB-P13735 (1 specimen, 455 mm TL), 20 July 2011 ; NMMB-P17506 (1 specimen, 478 mm TL), 4 Sep. 2010 ; NMMB-P24400 (1 specimen, 397 mm TL), 24 August 2016 ; TOU-AE7843 (1 specimen, 479 mm TL), 17 August 2020, off Dong-gang fish market, southwestern Taiwan. Other locality. NMMB-P12495 (5 specimens, 261–401 mm TL), 15 April 2011 , Phýờng Mũi Né, Việt Nam.

Diagnosis. Cephalic pores: SO 1 + 3, IO 4 + 2, POM 4 or 5 + 2, 3 temporal pores, single frontal pore ( Fig. 2A ). MVF: 9.8–77.4–173.3. Uniserial teeth on jaws and vomer ( Fig. 2B ). Lateral-line pores composition: PGLL 8.1, PDLL 11.1, PALL 79.4, TLL 164.3. Body gray to brownish in background, irregular patterns on dorsal side, pale ventrally.

Description. Well cylindrical body without compressed tail. Eye located from middle to one third of upper jaw near rictus; Eye small, length just about half of snout or shorter. Tubular anterior nostril moderately developed, downward from lateral view with each of AN have 2 short flaps inside; posterior nostril just a hole from the front edge to midpoint of eyes hind in mouth. Gill opening ventral, the margin of upper side oblique posteriorly.

Dorsal fin origin starts about 23.5% HL after gill opening. Cephalic pores are obvious in the mottled background without any pattern around: single ethmoid pore before AN, 2 nd SO pore placed in the central of snout, other SO pores and IO pores arranged near posterior side of eye. Head and trunk slightly shorter than tail (48.6% TL in average). Pectoral fin absent.

Dentition on both jaws uniserial, neatly arranged; 3 large teeth on middle-premaxilla arranged in an inverted “V” shape, visible when mouth closing; large teeth followed by a gap, then 18 vomerine teeth; 29–30 in both side of maxilla and the last 5 become smaller gradually; 49–50 on dentary in total, all teeth shape somewhat recurved ( Fig. 3 ).

Lateral line pores minute, difficult to distinguish: 7–9 before gill opening, 10–12 before dorsal fin origin, 76–85 before vent, and about 156–175 in total (the last c.a. 2.6% TL from tail tip invisible).

Body coloration. Pearl whitish in background and canary yellow covered when fresh, with mottled irregular patterns cover the whole head and the dorsal side of anterior 23.8% part of total length, followed by uniform brown or dark with regular white spot till the end of lateral line, each of spot corresponding to one lateral line pore; belly and median fin pale, no pattern covered ( Fig.1A ). Body overall white to yellowish when preserved, other pigmentation the same with fresh sample ( Fig. 1B ).

Distribution. Widespread in the western Pacific Ocean. North to Ryukyu Island, Japan, including Makiya and Teruma Beach, Okinawa ( Hibino et al., 2021); Southern Taiwan, including Kaohsiung (this study) and Ping-tung, Taiwan ( Ho et al., 2015); Nha Trang and Mui Ne, Vietnam ( Ho et al., 2015); west to Nicobar Island, India; Misol Island, Indonesia ( Günther, 1872); Philippines ( Bucol et al., 2010, McCosker, 2014); Fiji (Dr. J.E. McCosker, pers. comm.); and east to Queensland, Australia ( McCosker et al., 2006). Taiwanese specimens were caught at the range of 200–400 m by bottom trawlers, McCosker (2006) noted that they are benthic, burrowing species and live in coral rubble bottom, confirming the ecological information is still needed.

Genetic features. A Neighbor-Joining tree constructed by partial CO1 gene sequences (552 bp after processed by BioEdit software) of four voucher specimens in this study and the other two CO1 sequences obtained from NCBI (National Center for Biotechnology Information) supported the separation of these species ( Fig. 3 ). The GenBank accession numbers of 4 specimens examined in this study were attached following the voucher, in addition, the K2P distance matrix reveals that the distance ranged from 0.004 to 0.011 within Y. misolensis , 0.146 to 0.151 between Y. misolensis and Y. tenuis , and 0.182 to 0.213 between Yirrkala spp. and the outgroup ( Table 2 ).

Figures

FIGURE 1. Lateral view of Yirrkala misolensis. (A) Before fixing, TOU-AE7866, 351 mm TL with broken tail, Ke-tzu-liao fish market, Kaohsiung, Taiwan. Scale represents 10 mm. The position of dorsal fin origin and vent marked with red arrows. The center is a close-up view of cephalic part (Photo by W. -C. Huang). (B) When preserved, NMMB-P12003, 486 mm TL, mature female, Dong-gang fish market, Ping-tung, Taiwan, the position of dorsal fin origin and vent marked with pins.

FIGURE 2. Illustration of Yirrklala misolensis, NMMB-P12003, 486 mm TL, mature female, Dong-gang fish market, Pingtung, Taiwan. (A) Lateral view of head, arrows show the position of frontal pore and supratemporal pore. (B) Dentition.

FIGURE 3. Neighbor-joining tree based on CO1 sequences, constructed using the specimens mentioned in the present study and 1 congener from NCBI. The bar indicates the evolutionary distances which were computed using the Kimura 2-parameter method with 10,000 bootstrap-replicated.