A New Deep-water Species of Saurida (Pisces: Synodontidae) from the South China Sea and Central Philippines

© 2024 Academia Sinica, Taiwan Open Access A New Deep-water Species of Saurida (Pisces: Synodontidae) from the South China Sea and Central Philippines Barry C. Russell1,2,3,4,* , Maria Celia D. Malay5,6 , and Roxanne A. Cabebe-Barnuevo5,7 1Museum and Art Gallery of the Northern Territory, GPO Box 4646, Darwin NT 0801, Australia. *Correspondence: E-mail: barry[email protected].au (Russell) 2School of Environmental and Life Sciences, Charles Darwin University, Casuarina NT 0811, Australia 3Ichthyology, Australian Museum Research Institute, NSW 2010, Australia. 4Museums Victoria, Melbourne Museum, Victoria 3053, Australia 5University of the Philippines Visayas, Miag-ao Iloilo 5023, Philippines. 6Current affiliation: Marine Science Institute, University of the Philippines Diliman 1101 Quezon City, Philippines. E-mail: [email protected] (Malay) 7Current affiliation: Kagoshima University Museum, Kagoshima, Japan. E-mail: [email protected] (Cabebe-Barnuevo) urn:lsid:zoobank.org:pub:311E7F57-8867-4CBE-BD50-CD97BC3274EF Received 22 February 2024 / Accepted 19 July 2024 / Published 6 December 2024 Communicated by Hin-Kiu Mok A new species of lizardfish, Saurida weijeni sp. nov., from deep water of the outer slope of the North Macclesfield Bank (Zhongsha), South China Sea, and Guimaras Island, Western Visayas region of the Philippines, is described and figured. The new species is distinguished by the following combination of characteristics: dorsal fin with 11–12 rays; pectorals with 13–15 rays; lateral-line scales 49–52; transverse scale rows above the lateral line 3½, below the lateral line 5½; pectoral fins moderately long (extending to or just beyond a line from origin of pelvic fins to origin of dorsal fin); 2 rows of teeth on outer palatines; 0–3 teeth on vomer; tongue with about 3–4 rows of teeth posteriorly; 47–49 vertebrae; caudal peduncle compressed (depth greater than width); anterior part of stomach dusky or black, posterior extension pale whitish, intestine black. Saurida weijeni sp. nov. is genetically distinct from all other species of Saurida. Key words: Saurida weijeni sp. nov., Macclesfield Bank (Zhongsha), Guimaras Island, Western Visayas region, Philippines BACKGROUND The lizardfish genus Saurida (family Synodontidae) comprises about 25 species found in tropical and subtropical seas world-wide (Fricke et al. 2024). They commonly occur on continental shelfs associated with soft, muddy, or sandy bottoms in depths usually to about 200m, although some species are associated with shallow reef areas. In the Western Central Pacific, 11 species of Saurida are reported (Russell 1999) and 7 species are known from the South China Sea (Russell 2000). Sampling of trawl catches during a survey of the tropical deep-sea benthos of the Macclesfield Bank area (ZhongSha 2015 expedition) in the South China Sea (Fig. 1) in depths of 162–343 m, has yielded an additional new species. Other specimens, subsequently collected from Cabalagnan Fish Port, Guimaras Island, Western Visayas, Philippines (Fig. 1), were found to be the same undescribed species. Further investigation showed this species has been previously misidentified from the South China Sea as S. umeyoshii Inoue and Nakabo 2006 (Wang et al. 2014) but is genetically distinct from that species. The specimens examined in this study belong to the Saurida undosquamis species group characterised Citation: Russell BC, Malay MCD, Cabebe-Barnuevo RA. 2024. A new deep-water species of Saurida (Pisces: Synodontidae) from the South China Sea and central Philippines. Zool Stud 63:40. doi:10.6620/ZS.2024.63-40. Zoological Studies 63:40 (2024) doi:10.6620/ZS.2024.63-40 1 © 2024 Academia Sinica, Taiwan by Inoue and Nakabo (2006) as having dark dots on the upper margin of the caudal fin, pectoral fin exceeding origin of pelvic fin, anterior rays of dorsal fin neither elongate nor filamentous, predorsal length greater than distance between dorsal-fin and adipose-fin origins, 46– 55 pored lateral-line scales, and vomer with 0–8 teeth. Specimens collected from the North Macclesfield Bank and Guimaras Island differ morphologically as well as genetically from other species in the undosquamis group and are described herein as a new species. MATERIALS AND METHODS Specimens from Macclesfield Bank were collected from trawl catches during a survey of the tropical deepsea benthos of the Macclesfield Bank area (ZhongSha 2015 expedition) under the auspices of MUSORSTOM (a survey organized by the Muséum national d'Histoire naturelle and ORSTOM - Office de la Recherche Scientifique et Technique Outre-Mer – Head of Mission: Wei-Jen Chen, National Taiwan University) between 22 July 2015 and 1 August 2015. Specimens collected from Cabalagnan Fish Port, Guimaras Island, Western Visayas, Philippines were collected during a survey undertaken by the University of the Philippines Visayas as part of a broader project to establish a COI gene-sequence library for marine fishes of the Western Visayas region of the Philippines. Specimens are deposited in the Muséum national d’Histoire naturelle (MNHN), Paris; Museum and Art Gallery of the Northern Territory (NTM), Darwin; National Taiwan University Museum (NTUM), Taipei; and the Museum of Natural Sciences, University of the Philippines Visayas, Miagao Iloilo, Philippines (UPVMI). Methods of counting and measuring follow Shindo and Yamada (1972) and Inoue and Nakabo (2006). The following additional characteristics, not previously used, were also assessed: number of teeth rows on the tongue (counted as the number of teeth across the width of the posterior part of the tongue); depth and width of the caudal peduncle; and colour of the stomach and intestine (see Fishelson et al. 2012). Body length measurements are Standard Length (SL), measured from the tip of the snout, including the upper lip, to the Fig. 1. Map of South China Sea showing locations at which Saurida weijeni sp. nov. was collected. Red stars - Macclesfield Bank and Cabalagnan Fish Port, Guimaras Island, Philippines (Map credit: Nations Online Project). page 2 of 10Zoological Studies 63:40 (2024) © 2024 Academia Sinica, Taiwan posterior end of the midlateral portion of the hypural plate; Head Length (HL) measurements are from the tip of the snout to the posterior edge of the operculum. Measurements were taken with digital calipers to the nearest 0.1 mm. Vertebral counts were taken from radiographs. Proportional measurements were calculated as the percentage of SL or HL (Table 1). In the description, measurements and counts for the holotype are given first; those for the paratypes, where different from the holotype, are enclosed in parentheses. Institutional codes generally followed Sabaj (2020). For DNA barcoding, total DNA was extracted from muscle tissue preserved in 99.5% ethanol, Table 1. Morphometric and meristic data of the holotype (169.6 mm SL) and 11 paratype specimens (126.2–223.4 mm SL) of Saurida weijeni sp. nov. Morphometrics (% SL) Holotype Paratypes (n = 11) mean (range) Predorsal length 41.8 42.5 (38.0–44.8) Preadipose length 81.3 80.1 (74.1–83.4) Preanal length 72.9 73.0 (69.9–76.1) Preanal-fin length 75.0 75.7 (74.0–79.1) Prepectoral length 26.7 27.2 (25.6–29.6) Prepelvic length 37.9 39.1 (37.2–41.1) Head length (HL) 26.7 25.8 (24.3–27.2) Body depth 12.0 14.1 (11.3–17.3) Body width 14.9 13.7 (11.4–15.4) Interpelvic width 9.0 8.6 (7.9–9.3) Pectoral-fin length 16.1 15.9 (14.6–16.9) Pelvic-fin length 17.4 17.7 (16.2–18.8) Length of 2nd dorsal ray 18.5 18.8 (17.8–19.5) Length of last dorsal ray 6.1 5.9 (5.5–6.7) Length dorsal-fin base 13.2 13.3 (12.6–15.0) Length of 2nd anal ray - 8.4 (7.1–9.3) Length of last anal ray 5.7 5.6 (4.4–6.7) Length of anal-fin base 8.6 10.5 (9.0–11.5) Length of caudal peduncle 14.4 14.3 (10.4–16.8) Depth of caudal peduncle 5.7 5.5 (4.0–6.5) Width of caudal peduncle 4.6 4.9 (3.0–6.1) Morphometrics (% HL) Snout length 22.6 22.1 (19.1–23.8) Eye diameter 19.4 21.3 (18.3–23.4) Snout width 24.9 25.0 (22.2–29.4) Interorbital width 20.7 20.9 (19.1–23.6) Post orbital length 60.5 62.4 (54.8–98.6) Upper jaw length 67.6 69.2 (67.0–77.0) Meristics Dorsal fin 12 11–12 Pectoral fin 14 13–15 Pelvic fin 9 9 Anal fin 11 10–11 Pored lateral-line scales 52 49–52 Transverse scales above lateral line 3.5 3.5 Transverse scales below lateral line 5.5 5.5 Scale rows below lateral line with melanophores 2.5 2–3 Predorsal scales 20 17–19 Preadipose scales 16 14–16 Postadipose scales 13 10–12 No. vertebrae 49 47–49 No. rows of palatine teeth anteriorly 2 2 No. of vomerine teeth 0 0–2 No. teeth rows across tongue 4 3–4 page 3 of 10Zoological Studies 63:40 (2024) © 2024 Academia Sinica, Taiwan using the GF-1 Nucleic Acid Extraction Kit (Vivantis Technologies Sdn. Bhd, Malaysia) and PureLinkTM Genomic DNA Mini Kit (Invitrogen) extraction kits, according to the manufacturer’s protocols. The partial Cytochrome Oxidase submit I (COI) gene was amplified using the primers designed by Ward et al. (2005) (Fish F1–5'- TCAACCAACCACAAAGACATTGGCAC-3' and Fish R1–5'-TAGACTTCTGGGTGGCCAAAGAATCA-3'). The PCR thermo-cycling conditions used are as follows: 95°C for 2 mins (initial step), 35 cycles at 94°C for 30 sec (denaturation), 54°C for 30 sec (annealing), 72°C for 40 sec (extension), and 72°C for 10 min (final extension). The PCR products were visualized on 1% agarose gels. Sequencing of the samples was performed at Macrogen Inc. (South Korea). Sequence data was deposited in GenBank and Bar Code of Life Data System (BOLD), the accession numbers and metadata of all evaluated DNA sequences are summarized in table S1. Forward and reverse sequences were checked, trimmed, and assembled into contigs using Unipro UGENE software (Okonechnikov et al. 2012). The sequences determined here were aligned using Multiple Sequence Comparison by Log-Expectation (MUSCLE) software (Edgar 2004) as implemented in MEGA version 10.2.4 (Stecher et al. 2020). From the aligned sequences, the best evolutionary model was found using MEGA, the Kimura 2-parameter model with invariant sites (K2P+I) being selected by the Bayesian Information Criterion. Pairwise nucleotide genetic distances were calculated using the Kimura 2-parameter model (K2P; Kimura 1980) in MEGA. A maximum likelihood tree was reconstructed using MEGA, and node support measured using nonparametric bootstrapping with 1,000 replications. COI sequences from taxonomically verified and vouchered Saurida spp. specimens (Furuhashi et al. 2022) were included in the analysis, while the COI sequence of Harpadon nehereus, which belongs to the same subfamily as Saurida, was included as an outgroup. RESULTS Saurida weijeni Russell, Malay and CabebeBarnuevo sp. nov. Common name: Wei-Jen’s lizardfish (Figs. 2–4. Table 1) urn:lsid:zoobank.org:B020479F-BB1E-4BFF-8AE9DCF51D26A27C Saurida umeyoshii (not of Inoue and Nakabo 2006): Wang et al. 2014: 1399 (South China Sea). Holotype: NTUM 17606, sample id. No. WJC 5756, 233.3 mm SL, South China Sea, outer slope of North Macclesfield Bank, ZhongSha 2015 Trawl Survey Station CP CP4147, 16°09.83'N, 114°15.25'E–6°08.15'N, 114°17.97'E, 259–343 m, WeiJen Chen, RV Ocean Researcher 1, 26 July 2015. Paratypes: Eleven specimens, 126.2–223.4 mm SL. NTUM 17604, sample id. No. WJC 5713, 166.7 mm SL, South China Sea, outer slope of North Macclesfield Bank, ZhongSha 2015 Trawl Survey Station CP4146, 16°07.60'N, 114°18.83'E–16°09.29'N, 114°16.23', 232–314 m, Wei-Jen Chen, RV Ocean Researcher 1, 26 July 2015. NTUM 17605, sample id. No. WJC 5714, 169.6 mm SL, same data as preceding. NTM S.18814– 001, sample id. No. WJC 5757, 188.2 mm SL, South China Sea, outer slope of North Macclesfield Bank, ZhongSha 2015 Trawl Survey Station CP4147, same data as holotype. NTM S.18815–001, 3: sample id. No. WJC 5786, 202.7 mm SL, sample id. No. WJC 5787, 218.3 mm SL, sample id. No. WJC 5788, 171.2 mm SL, South China Sea, outer slope of North Macclesfield Bank, ZhongSha 2015 Trawl Survey Station CP4148, 16°08.60'N, 114°17.22'E–16°07.33'N, 114°19.21'E, 218–281 m, Wei-Jen Chen, RV Ocean Researcher 1, 26 July 2015. MNHN 2022-0330, 3: sample id. No. WJC 5832, 136.7 mm SL; sample id. No. WJC 5833, 133.4 mm SL; sample id. No. WJC 5834, 126.2 mm SL, South China Sea, outer slope of North Macclesfield Bank, ZhongSha 2015 Trawl Survey Station CP4149, 16°06.54'N, 114°20.05'E–16°06.75'N, 114°22.97'E, 162–165 m, Wei-Jen Chen, RV Ocean Researcher 1, 26 July 2015. UPVMI–01361, sample id. No. BAR-829, 205.6 mm SL, Philippines, Guimaras Island, Western Visayas, Cabalagnan Fish Port, purchased 29 November 2020. UPVMI–01362, sample id. No. BAR-830, 223.45 mm SL, same data as preceding. Diagnosis: A moderately large species of Saurida, with the following combination of characters: dorsal fin with 11–12 rays; pectorals with 13–15 rays; lateralline scales 49–52; transverse scale rows above lateral line 3½, below lateral line 5½; pectoral fins moderately long, reaching beyond a line from origin of pelvic fins to origin of dorsal fin; 2 rows of teeth on outer palatines; 0–2 teeth on vomer; tongue with about 3–4 rows of teeth posteriorly; caudal peduncle rounded (depth about equal to width); anterior part of stomach dusky or black, posterior extension pale whitish, intestine black; leading edge of upper lobe of caudal fin with 3–6 black spots. Description: Counts and proportional measurements of the type series are provided in Table 1. Dorsal-fin rays 12 (11–12); pectoral-fin rays 14 (13–15); pelvic-fin rays 9; anal-fin rays 11 (10–11). Pored lateralline scales 52 (49–52); transverse scale rows above lateral line 3½, transverse scale rows below lateral line 5½, scale rows below lateral line with melanophores 2½ page 4 of 10Zoological Studies 63:40 (2024) © 2024 Academia Sinica, Taiwan (2–3); predorsal scales 20 (17–19); pre-adipose scales 16 (14–16); post-adipose scales 13 (10–13). Vertebrae 49 (47–49). Body elongate and cylindrical, somewhat depressed on head and compressed on caudal peduncle, the latter with slightly raised lateral line scales, forming a slight ridge; scales large, cycloid, deciduous; scales present on cheek and opercle. Snout rounded when viewed from above. Nostrils located about midway between snout tip and anterior margin of orbit; anterior nostrils a little larger than posterior, anterior one with a broad dermal flap posteriorly. Eye circular, directed laterally, covered with fleshy adipose eyelid anteriorly and posteriorly. Interorbital region broad, slightly concave. Mouth very large, the gape extending well beyond posterior margin of eye. Teeth on jaws numerous, small, canine-like, generally in four rows, outermost teeth smallest, innermost longest, visible when mouth closed; similar teeth on the palate, tongue and branchial arches; palatine teeth in two separate series: teeth of outer series long, in two rows, with anterior teeth longer, teeth of inner series short, in about six poorly defined rows; outer palatine series converge anteriorly but separated by vomer which is toothless (or with 0–2 teeth); tongue short, spatulate, fleshy, with triangular shaped patch of teeth, in about 4 (3–4) rows posteriorly; lower jaw slightly shorter than upper jaw and fits into groove between teeth at tip of upper jaw; gill rakers absent, branchial arches each with about 4 rows of teeth, those on the inside largest. Origin of dorsal fin just anterior to midpoint of distance from snout to adipose fin origin; base of dorsal fin longer than that of anal fin; adipose fin above posterior half of anal fin; anus just anterior to origin of anal fin; pectoral fins moderately long, 16.1% (14.6– 16.6%) in SL, tip of pectoral fin reaching beyond a line from base of pelvic fin to origin of dorsal fin (P–D line); pectoral and pelvic fins with long and pointed axillary scales, those of pelvic a little shorter; caudal fin deeply forked, upper and lower lobes about equal. Colour of fresh specimens (Figs. 2, 3): Top of head and back dark brown or coppery brown, some scales narrowly edged with black, forming a variegated pattern; paler 2–3 scale rows below lateral line, ventral surface silvery white; dorsal fin translucent, leading edge with 6 (3–5) indistinct spots; adipose fin dusky on outer half of fin; caudal fin translucent, leading edge of upper lobe with 5 (4–5) blackish spots, outer part of lower lobe dusky; pectoral fins dusky, base of Fig. 2. Saurida weijeni sp. nov. Holotype NTUM 17606 (WJC 5756), 233.3 mm SL, South China Sea, North Macclesfield Bank showing freshly caught colours (Photo credit: W-J Chen). Fig. 3. Saurida weijeni sp. nov. Paratype UPVMI–01361 (BAR-829), 205.6 mm SL, Philippines, Guimaras Island, Western Visayas, Cabalagnan Fish Port showing freshly caught colours (Photo credit: RA Cabebe-Barnuevo). page 5 of 10 Zoological Studies 63:40 (2024) © 2024 Academia Sinica, Taiwan fin translucent; pelvic fins and anal fin translucent. Peritoneum pale whitish; anterior part of stomach dusky or black, posterior extension pale whitish, intestine black. Colour in alcohol (Fig. 4): Brown on back, paler below lateral line, pigment extending to about 2½ (2–3) scale rows below lateral line; pectoral fins dusky over outer two thirds of fin; pelvic fins pale; dorsal, caudal and anal fins pale, anterior margin dorsal fin with indistinct spots; upper leading edge of upper lobe of caudal fin with 6 (3–5) spots, lower lobe of fins dusky on outer half; adipose fin dusky on outer half. Peritoneum whitish; anterior part of stomach dusky or black, posterior extension pale, intestine black. Etymology: Named in honour of Professor WeiJen Chen, Institute of Oceanography, National Taiwan University, who collected this species during an exploratory fish survey of the Macclesfield Bank area of the South China Sea. The name weijeni is treated here as a noun in the genitive case (ICZN 1999, Article 31.1). The common English name Wei-Jen’s lizardfish is proposed for this species. Distribution: Saurida weijeni sp. nov. has only been recorded from the South China Sea and from Cabalagnan Fish Port, Guimaras Island, Western Visayas, Philippines (Fig. 1). Specimens collected from the outer slope of the North Macclesfield Bank, South China Sea, were trawled in depths of 162–343 m. The Macclesfield Bank (Zhongsha) lies east of the Paracel Islands, southwest of Pratas Island and north of the Spratly Islands, and comprises many entirely submerged banks, seamounts, and shoals in the South China Sea. It is about 130 km long from southwest to northeast, and about 70 km wide at its broadest part (Huang et al. 2020; United States National GeospatialIntelligence Agency 2020). With an ocean area of 6,448 km2 it is one of the largest submerged atolls of the world. In general, the central lagoon is very deep, with depths up to 100 m and outside of the banks, depths quickly drop to more than 1000 m. Specimens collected from Cabalagnan Fish Port, Guimaras Island, Western Visayas, in the Philippines lacked information on fishing gear, collection depth, or specific locality, but were presumably fished in deeper water from either Guimaras Strait or the Sulu Sea. Genetic analysis: COI sequence fragments of 544 base pairs were recovered from twelve specimens of Saurida weijeni sp. nov. Two COI haplotypes were observed, with the sequence from Macclesfield Bank differing at two nucleotide positions from the haplotype from the Philippines (intraspecific K2P genetic difference = 0.37%). Notably, the haplotype from the Philippines is identical to GenBank sequence KM189365.1 from the South China Sea, identified as Saurida umeyoshii by Wang et al. (2014) in their study of the complete mitochondrial genome of that species. Unfortunately, a request to the corresponding author of this study for a photograph and/or the voucher specimen of KM189365.1 for verification was unsuccessful and it seems that their specimen was misidentified. Incorrect species identification in public sequence databases such as GenBank is a growing problem (Hung et al. 2017) and this case further emphasises the importance of accurate taxonomic identification and/or verification using museum voucher specimens in DNA barcoding and systematic studies. A total of 571 COI sequences from other Saurida species were retrieved from GenBank and the BOLD system (accessed March 19, 2024) and a preliminary maximum likelihood COI tree was reconstructed with all available sequences, including S. weijeni sp. nov. Initial screening to identify Operational Taxonomic Units (OTUs) based on a threshold of ≥ 3% COI divergence in K2P distance (Ward et al. 2009) in this large and complex tree, showed S. weijeni sp. nov. to be genetically divergent from all other species of Saurida. The preliminary ‘total’ maximum likelihood COI tree of Saurida and its OTU’s is the subject of continuing analysis by BCR that is beyond the scope of this paper. For this reason, only Western Pacific congeners of the S. undosquamis group (S. fortis, S. macrolepis, S. umeyoshii, S. undosquamis, S. weijeni sp. nov.) are included in the partial maximum likelihood COI tree that is presented here (Fig. 5), primarily to indicate Fig. 4. Saurida weijeni sp. nov. Paratype UPVMI–01361 (BAR-829), 205.6 mm SL, colours after preservation (Photo credit: RA Cabebe-Barnuevo). page 6 of 10Zoological Studies 63:40 (2024) © 2024 Academia Sinica, Taiwan Fig. 5. Maximum likelihood tree based on mitochondrial COI DNA sequences. Numbers on the nodes represent bootstrap support values. Abbreviations: AUS NT = Australia, Northern Territory; AUS WA = Australia, Western Australia; IND = Indonesia; JP = Japan; PH = Philippines; THA = Thailand; TW = Taiwan. page 7 of 10Zoological Studies 63:40 (2024) © 2024 Academia Sinica, Taiwan K2P genetic differences rather than infer phylogenetic relationships. Based on recent sequence data for the true Saurida umeyoshii (Furuhashi et al. 2022) interspecific K2P genetic difference between Saurida weijeni sp. nov., including KM189365.1, and S. umeyoshii is 13.1 ± 0.1%. Average interspecific K2P genetic differences with other closely related congeners ranged from 10.5 ± 0.7% (S. weijeni sp. nov. vs. S. undosquamis) to 12.0 ± 0.2% (S. weijeni sp. nov. vs. S. macrolepis). A maximum likelihood tree based on COI sequences (Fig. 5) showed S. weijeni sp. nov. to be reciprocally monophyletic with S. umeyoshii and other Saurida species. Comparative material: Saurida fortis (41 specimens, 120.0–499.8 mm SL): listed in Furuhashi et al. (2022), from Japan, Taiwan, and Thailand. Saurida lessepsianus (38 specimens, 108.0–282.2 mm SL): listed in Russell et al. (2015), from Red Sea and eastern Mediterranean Sea. Saurida macrolepis (10 specimens, 135.5–210.5 mm SL): BSKU 58129, 137.0 mm SL, BSKU 58130, 162.1 mm SL, BSKU 58131, 204.4 mm SL – Iburi fishing port, Tosa Bay, Kochi, Japan; NTUM 145372, 4: 176.5–210.5 mm SL – Iorigawa fishing port, Miyazaki, Japan; MUFS 25074, 135.5 mm SL; ZUMT 7478, 196.1 mm SL, ZUMT 7479, 192.6 mm SL – Tokyo Fish Market, Japan. Saurida umeyoshii (11 specimens, 216.8–332.0 mm SL): BSKU 32666, 255.0 mm SL, BSKU 33029, 332.0 mm SL, BSKU 33114, 281.8 mm SL, BSKU 33116, 244.8 mm SL, BSKU 33117, 232.4 mm SL, BSKU 33118 239.3 mm SL, BSKU 34325, 288.3 mm SL, BSKU 34326, 244.6 mm SL, BSKU 34327, 239.2 mm SL, BSKU 34328, 266.5 mm SL – Okinawa Trough, Japan; BSKU 85776, 216.8 mm SL – Mimase, Kochi, Japan. Saurida undosquamis (18 specimens, 162.6–346.6 mm SL): listed in Russell et al. (2015), from Northwestern Australia. Saurida cf. undosquamis: (6 specimens, 75.7–335.0 mm SL): ASIZ P0807036, 186.42 mm SL – Keelung, Taiwan; ASIZ P0076118, 317.7 mm SL, P0076119, 288.2 mm SL – Chia-Yi, Taiwan; NTM S.16884-003, 335.0 mm SL – Hengchung market, Taiwan; NTUM 14370, 301.8 mm SL – Mimase fishing port, Tosa Bay, Japan; NTUM 14373, 75.7 mm SL – Iburi fishing port, Tosa Bay, Japan. DISCUSSION Inoue and Nakabo (2006), in a review of the Saurida undosquamis group, showed the name S. undosquamis (type locality: northwestern Australia) has been applied to a complex of species distributed widely throughout the Indo-West Pacific. They recognised three species from the Western Pacific in the group (S. undosquamis Richardson, 1848; S. umeyoshii Inoue and Nakabo, 2006; S. macrolepis Tanaka, 1917) and one Table 2. Comparison of selected morphological characters of Saurida weijeni sp. nov. and other Western Pacific species of the “S. undosquamis” group: S. umeyoshii, S. undosquamis, S. macrolepis and S. fortis S. weijeni sp. nov. S. umeyoshii S. undosquamis S. macrolepis S. fortis South China Sea, Philippines n = 12 Japan, n = 11 NW Australia, n = 18 Japan, n = 10 Japan, Taiwan, Thailand n = 41 Pectoral-fin tip Extending to or just beyond P–D line Extending beyond P–D line To or just short of P–D line Just short of or extending slightly beyond P–D line Just short of or extending slightly beyond P–D line Body colour above lateral line Dark brown Dark brown Light brown Dark brown Dark brown Melanophores below lateral line (adults) On 2–3 scale rows below lateral line All scales On 1–5 scale rows below lateral line On 1–3 scale rows below lateral line All scales, but more sparse ventrally Black spots along caudal-fin upper margin 3–5 indistinct 7 distinct 4–12 distinct 3–8, sometimes indistinct Indistinct Colour of stomach Dusky or black Pale black Whitish Dusky or black Whitish or greyish (pale black in young) Colour of intestine Black Dense black Whitish or pale grey Black Greyish or pale Teeth rows on tongue 3–4 3–5 7–12 3–7 3–6 Vertebrae 47–49 47–51 50–54 45–47 51–54 Lat line scales 49–52 49–52 52–59 48–52 53–56 page 8 of 10Zoological Studies 63:40 (2024) © 2024 Academia Sinica, Taiwan from the Western Indian Ocean (S. longimanus Norman, 1939). To this group may be added: S. lessepsianus Russell, Golani and Tikochinsky, 2015 from the Western Indian Ocean–Red Sea, and a now widely invasive species in the eastern Mediterranean Sea; S. fortis Furuhashi, Russell and Motomura, 2022 from Japan; and S. weijeni sp. nov. described here. It should be noted that Saurida undosquamis sensu Inoue and Nakabo (2006) may comprise more than one species (Furuhashi et al. 2022) and is the subject of ongoing study by BCR. Saurida weijeni sp. nov. differs from other Western Pacific species of the S. undosquamis group (Table 2) as follows: lateral-line scales, 49–52 (versus 54–58 in S. undosquamis and 53–56 in S. fortis); fewer vertebrae, 47–49 (versus 50–54 in S. undosquamis and 51–54 in S. fortis); and has a black or dusky stomach and intestine (versus whitish pale grey in S. undosquamis and S. fortis). It differs from S. umeyoshii in having melanophores on the body extending only 2–3 scale rows below the lateral line (versus melanophores on all scales to ventral midline in S. umeyoshii) and having 3–5 indistinct black spots (versus 7 distinct spots in S. umeyoshii) on the upper margin of the caudal fin. Morphologically, Saurida weijeni sp. nov. appears most closely related to S. macrolepis but differs from that species in having 47–49 vertebrae (versus 45–47 vertebrae in S. macrolepis) and is genetically distinct (K2P genetic difference 12.3% – Fig. 5). Acknowledgments: The trawl survey of the Macclesfield Bank by the RV Ocean Researcher was undertaken as part of the ZhongSha 2015 Tropical Deep-Sea Benthos (ex MUSORSTOM) Project. Thanks are due to Professor Wei-Jen Chen, who facilitated a visit by BCR to examine collections of deeper water trawl fishes at the National Taiwan University (NTUM); and to Shih-Yu Wang (NTUM), who undertook genetic analysis of specimens, and Hsiu-Chen Lin (NTUM) for specimen management and assistance in laboratory work. MCDM and RAC-B acknowledge funding support from the University of the Philippines Emerging Interdisciplinary Research (OVPAA-EIDR-C08-011-R) and the Leverage fund from the Office of the Vice Chancellor for Research and Extension, University of the Philippines Visayas (UPV). We also thank the Provincial Government and Provincial Agriculture Office of Guimaras for facilitating the sampling, as well as the field enumerators, staff, volunteers, and students at the University of the Philippines Visayas, Philippine Genome Center Visayas, and the UPV–Museum of Natural Sciences for their generous help throughout the project. Authors’ contributions: BCR and RAC-B performed the morphometrics examinations. BCR, MCDM and RAC-B produced and analyzed the data and wrote and reviewed the manuscript. All authors read and approved the final version of the manuscript. Competing interests: The authors declare that they have no competing interests. Availability of data and materials: All mitochondrial COI DNA sequences in this study are available in GenBank. The metadata of the samples are attached in the Supplementary Materials. Consent for publication: Not applicable. Ethics approval consent to participate: Not applicable. REFERENCES Edgar RC. 2004. MUSCLE: multiple sequence alignment with high accuracy and high throughout. Nucleic Acids Res 32:1792–1797. doi:10.1093/nar/gkh340. Fishelson L, Golani D, Russell B, Galil B, Goren M. 2012. Melanization of the alimentary tract in lizardfishes (Teleostei, Aulopiformes, Synodontidae). Environ Biol Fish 95:195–200. doi:10.1007/s10641-012-9982-8. Fricke R, Eschmeyer WN, Van der Laan R (eds). 2024. Eschmeyer’s catalog of fishes: Genera, species, references. Available at: http:// researcharchive.calacademy.org/research/ichthyology/catalog/ fishcatmain.asp. (Electronic version accessed 20 Apr. 2024). Furuhashi R, Russell BC, Motomura H. 2022. Saurida fortis, a new species of lizardfish (Aulopiformes: Synodontidae) from the northwestern Pacific Ocean. Ichthyol Res 70:337–352. doi:10.1007/s10228-022-00894-x. Huang H, He E, Qiu X, Guo X, Fan J, Zhang X. 2020. Insights about the structure and development of Zhongsha Bank in the South China Sea from integrated geophysical modelling. Int Geol Rev 62:7–8, 1070–1080. doi:10.1080/00206814.2019.1653798. Hung K-W, Russell BC, Chen WJ. 2017. Molecular systematics of threadfin breams and relatives (Teleostei, Nemipteridae). Zool Scr 46:536–551. doi:10.1111/zsc.12237. ICZN. 1999. International Code of Zoological Nomenclature. 4th edn. The International Trust for Zoological Nomenclature, London, UK. Inoue T, Nakabo T. 2006. The Saurida undosquamis group (Aulopiformes: Synodontidae), with description of a new species from southern Japan. Ichthyol Res 53:379–397. doi:10.1007/ s10228-006-0358-y. Kimura M. 1980. A simple method for estimating evolutionary rates of base substitutions through comparative studies of nucleotide sequences. J Mol Evol 16:111–120. doi:10.1007/BF01731581. Norman JR. 1939. Fishes. The John Murray Expedition 1933-34. Sci Rep, John Murray Exped 7:1–116. Okonechnikov K, Golosova O, Fursov M. 2012. Unipro UGENE: a unified bioinformatics toolkit. Bioinformatics 28:1166–1167. doi:10.1093/bioinformatics/bts091. Richardson J. 1848. Ichthyology of the voyage of H. M. S. Erebus & Terror. In: Richardson, J, Gray JE (eds.), The zoology of the page 9 of 10Zoological Studies 63:40 (2024)