Uropterygius hades, Huang & Hibino & Balisco & Liao, 2024

Huang, Wen-Chien, Hibino, Yusuke, Balisco, Rodulf Anthony & Liao, Te-Yu, 2024, Description of a new uniformly brown estuarine moray eel (Anguilliformes, Muraenidae) from the Central Indo-Pacific Ocean, ZooKeys 1220, pp. 15-34 : 15-34

publication ID	https://doi.org/ 10.3897/zookeys.1220.129685
publication LSID	lsid:zoobank.org:pub:F5B389BC-9656-4288-A277-D236526727D8
DOI	https://doi.org/10.5281/zenodo.14342614
persistent identifier	https://treatment.plazi.org/id/F3796406-C030-55A7-9C70-2BED3A537469
treatment provided by	ZooKeys by Pensoft
scientific name	Uropterygius hades
status	sp. nov.

Treatment

Uropterygius hades sp. nov.

Figs 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , Table 1 Common name: Hades’ snake moray View Table 1

Uropterygius concolor View in CoL (not of Rüppell): Sakai and Sato 1982: 79, fig. 1, pl. I-A (Amami and Okinawa islands, Japan); Hatooka and Yoshino 1982: 95, fig. 6, pl. IV (Okinawa and Ishigaki islands, Japan); McCosker et al. 1984: 262 (Amami, Okinawa, and Ishigaki islands, Japan); Maeda and Tachihara 2006: 19, table 1 (Okinawa Island, Japan); Kanda et al. 2009: fig. 3 A, table 1 (Ishigaki island, Japan); Hibino 2018 in Motomura et al. 2018: 25, unnumbered fig. (Kakeroma Island, Japan); Miyake et al. 2019: fig. S 1 c, table 2 (Okinawa Island, Japan).

Uropterygius cf. concolor View in CoL 4: Huang et al. 2023 a: 595, figs 1, 3, tables 2, 3 (Ryukyu Archipelago, Japan; possibly Fiji and southern Java, Indonesia).

Type material.

Holotype. • NMMB-P 039570 (349 mm TL, male); estuary of the Zhuan River (24°50'24.7"N, 121°49'18.1"E), Yilan County, northeastern Taiwan; dip net at 1.5 m, 11 January 2024, coll. W. C. Jhuang; GenBank COI accession number PP 817258 GoogleMaps .

Paratypes. 10 specimens (163–313 mm TL). Japan: • KAUM–I.128986 (205 mm, sex unknown), Sumiyo Bay , Amami Island, Amami group, Kagoshima Prefecture, 20 March 2019, coll. R. Furuhashi • KAUM–I.132509 (171 mm, mature female), tidal flat of Sumiyo Bay , Amami Island, Amami group, Kagoshima Prefecture, 31 August 2019, coll. R. Furuhashi • KAUM–I.153507 (264 mm, mature female), mouth of Yakukachi River , Sumiyo, Amami Island, Amami group, Kagoshima Prefecture, 27 April 2002, coll. T. Yonezawa • KAUM –I.177723 (215 mm, sex unknown) • KAUM–I.177724 (190 mm, sex unknown), Setouchi , Kakeroma Island, Amami group, Kagoshima Prefecture, 23 November 2022, coll. S. Hashimoto • KMNH VR 100621 (231 mm, mature female), Oura River , Okinawa Island, Okinawa Prefecture, 20 May 2023, coll. K. Takatsuki • KYUM-PI 4637 (246 mm, sex unknown), Oura River , Okinawa Island, Okinawa Prefecture, 6 October 2014, coll. K. Maeda • URM-P 48530 (163 mm, sex unknown) • URM-P 48531 (204 mm, sex unknown), coll. with KYUM-PI 4637, GenBank accession numbers AP 019352 View Materials and AP 019353 View Materials . Philippines: • PNM 15806 View Materials (313 mm, mature female), inside the cave, about 50 m from the entrance of the Puerto Princesa Subterranean River (10°11'55.6"N, 118°55'33.7"E), Palawan, tube trap at the bottom of the river, about 9.6 m depth, 03 May 2023, coll. W. C. Huang, R. A. Balisco, and W. C. Jhuang, GenBank COI accession number PP 817259 GoogleMaps .

Non-type material.

Three specimens (148–158 mm TL). Fiji: • AMS I.43866-001 (158 mm, sex unknown), mid Suetabu River , Vanua Levu, February 2006 . Indonesia: • ZRC 44083 View Materials (148 mm, sex unknown), Ujung Genteng , southern Java, obtained through aquarium trade, 02 October 1999 . Philippines: • ZRC 63518 View Materials (155 mm, sex unknown), Matutinao River , Badian, Cebu, 25 November 2001 .

Diagnosis.

A small, slender moray eel, possible maximum TL <350 mm, female mature at 171 mm TL. Anus at mid-length of body. Eyes small and anteriorly placed. Snout pointed. Upper jaw slightly longer than lower jaw. Teeth sharply pointed with smooth edges and recurved tips; intermaxillary teeth in 5 rows; maxillary and dentary teeth biserial, inner rows extending to about posterior end of jaws; vomerine teeth in single row. No branchial pore. Body uniformly dark brown; head pores, oral cavity, and inner skin of posterior nostril and gill opening whitish; iris reddish-brown. Total vertebrae 117–122.

Description.

Values shown below from all the 14 specimens, including holotype, paratypes, and non-types. Proportions in percentage of TL: tail length 47.6–51.4 (x ̄ = 49.6); preanal length 48.6–52.4 (x ̄ = 50.4); trunk length 35.8–41.3 (x ̄ = 38.6); head length 10.5–12.8 (x ̄ = 11.8); body depth at gill opening 2.9–4.4 (x ̄ = 3.7); body depth at anus 3.3–5.0 (x ̄ = 3.8). Proportions in percentage of HL: length of upper jaw 26.3–35.1 (x ̄ = 29.9); length of lower jaw 25.5–33.6 (x ̄ = 28.9); interorbital width 5.9–9.6 (x ̄ = 7.9); snout length 9.3–12.0 (x ̄ = 10.5); eye diameter 5.0–7.2 (x ̄ = 5.8). Vertebral counts: pre-anus vertebrae 55–58 (x ̄ = 57); pre-dorsal fin vertebrae 102–109 (x ̄ = 105); pre-anal fin vertebrae 103–110 (x ̄ = 106); total vertebrae 117–122 (x ̄ = 119) (Table 1 View Table 1 ).

A small, slender moray eel, anus at mid-length of body, tail laterally compressed, body depth roughly consistent throughout whole fish except for narrower, pointed head and tail tip (Figs 3 View Figure 3 , 4 View Figure 4 ). Fins inconspicuous and restricted to posterior portion of tail, caudal fin short. Gill opening small and oval, below lateral midline of body. Eyes small and anteriorly placed, closer to snout tip than to mouth corner, snout / upper jaw length 0.30–0.40 (x ̄ = 0.36). Snout short and somewhat pointed, space between eyes narrow, anterior portion of head triangular in dorsal view. Jaws moderately long, upper jaw slightly longer than lower jaw, teeth not visible when mouth closed. Anterior nostril short and tubular, close to tip of snout, shorter than eye dimeter in length. Posterior nostril a large oval hole with a raised rim, above and posterior to anterior margin of eye, opening upward (Fig. 5 View Figure 5 ).

Three supraorbital pores, first and second pores on tip of snout; first pore below base of anterior nostril; second pore next to upper base of anterior nostril at horizontal level of lower eye margin; third pore on upper margin of snout, above and posterior to first infraorbital pore. Four infraorbital pores, arranged along upper jaw with equal intervals, first pore posteriorly next to base of anterior nostril; second pore below and anterior to eye; third pore below midpoint of eye; fourth pore below and posterior to eye. Six preoperculo-mandibular pores lining along lower jaw anterior to mouth corner (Fig. 5 A View Figure 5 ). No branchial pore observed except in one specimen ( ZRC 63518) having one pore on left side of posterior-dorsal head, representing a rare variation.

Teeth sharply pointed with smooth edges and recurved tips. Intermaxillary tooth plate with 5 rows of teeth; peripheral rows with 8–13 (mode 9) tightly arranged small teeth on each side; teeth on intermediate and median rows significantly larger than those on peripheral rows, about twice as tall and depressible, intermediate rows with 3–6 (3) teeth on each side, median row with 2–5 (3) teeth. Maxillary teeth biserial; outer row with 18–36 (26 and 28) teeth, continuous with peripheral intermaxillary teeth of similar size and shape, teeth slightly smaller at posterior end; inner row with 7–19 (11 and 13) straight, widely spaced teeth, continuous with intermediate intermaxillary teeth of approximately the same size and shape, extending to, exceeding, or near posterior end of outer row, with teeth becoming smaller at posterior end. Vomerine with 2–9 (5) small, conical teeth in single row. Dentary teeth biserial; outer row with 26–43 (36) teeth, small and equal-sized, closely arranged; inner row with 8–22 (13) slender and straight teeth, twice taller than teeth on outer row, widely spaced, anterior and posterior teeth smaller than middle ones, extending to or near posterior end of outer row (Fig. 6 View Figure 6 ).

Body uniformly dark brown, color slightly lighter ventrally, covered with greenish mucus when alive. Head pores, oral cavity, and inner skin of posterior nostril and gill opening whitish. Iris reddish-brown. Whitish superficial neuromasts arranged in several lines on head region and in a row along lateral body (Fig. 5 B View Figure 5 ). Preserved color mostly same as in fresh, but slightly faded.

Distribution.

This species is widely distributed in estuaries of the Central Indo-Pacific Ocean, ranging from southern Java to Fiji, and extending north to the Ryukyu Archipelago of Japan.

Etymology.

The new moray eel is named after Hades, the ancient Greek god of the underworld, in reference to its habitation in turbid estuarine waters, high sensitivity to light, and its uniformly dark coloration, reminiscent of the underworld god. A noun in apposition.

Comparisons.

In molecular analyses, the topology of the COI tree (Fig. 2 View Figure 2 ) reveals that U. hades sp. nov., U. concolor , U. cf. concolor 1, U. cf. concolor 2, U. cf. concolor 3, and U. mactanensis are monophyletic, which concord with the findings of Huang et al. (2023 a). Two COI sequences from GenBank, originally identified as “ U. concolor ” ( AP 019352 View Materials and AP 019353 View Materials ), clustered with the two U. hades sp. nov. sequences generated in this study. The two voucher specimens, URM-P 48530 and URM-P 48531 , have been examined and designated as paratypes of U. hades sp. nov. Additionally, a sequence from BOLD Systems identified as “ Gymnothorax australicola ” ( PHILV 560-15) was found to cluster with U. cf. concolor 1 (Fig. 2 View Figure 2 ). This extends the possible distribution range of U. cf. concolor 1 northward to the Philippines, where it overlaps with U. hades sp. nov. and U. mactanensis (Fig. 1 View Figure 1 ). Lastly, large K 2 P genetic distances were observed between U. hades sp. nov. and U. concolor (18.1 %), U. cf. concolor 1 (18.5 %), U. cf. concolor 2 (17.1 %), U. cf. concolor 3 (20.0 %), and U. mactanensis (19.7 %), further supporting the validity of the new species.

In morphological comparisons, U. hades sp. nov. can be easily distinguished from U. concolor (including its three synonyms) and U. mactanensis by its exclusively small eyes (5.0–7.2 % vs 7.7–11.0 % and 7.8–10.4 % of HL), absence of branchial pore (vs one in both species) and extended inner rows of teeth reaching the posterior end of jaws (Table 2 View Table 2 ). Uropterygius hades sp. nov. has a similar vertebral formula to U. concolor (Fig. 7 View Figure 7 ), but the former has a shorter tail compared to the latter (47.6–51.4 % vs 52.4–60.0 % of TL). Additionally, despite overlapping in tail length proportions, U. hades sp. nov. differs from U. mactanensis by having a narrower body depth at gill opening (2.9–4.4 % vs 5.1–6.5 % of TL), a shorter snout (9.3–12.0 % vs 12.6–15.7 % of HL), shorter jaws (25.5–35.1 % vs 32.7–40.9 % of HL), a narrower interorbital width (5.9–9.6 % vs 9.1–13.0 % of HL), and more vertebrae (117–122 vs 107–112) (Table 1 View Table 1 ). Morphological data for the remaining members of the U. concolor species complex (i. e., U. cf. concolor 1, U. cf. concolor 2, and U. cf. concolor 3) are quite limited and cannot be compared with the new species, except for one COI sequence-bearing specimen of U. cf. concolor 3 ( WAM P. 34389-001, 301 mm TL) with 112 total vertebrae ( Huang et al. 2023 a). Nevertheless, the tree topology and genetic distances between each clade strongly support their classification as different species (Fig. 2 View Figure 2 ).

Uropterygius hades sp. nov. may also be confused with six uniformly brown moray eels in the genus, namely Uropterygius cyamommatus Huang, Liao & Tan, 2023 , Uropterygius genie Randall & Golani, 1995 , Uropterygius golanii McCosker & Smith, 1997 , Uropterygius inornatus Gosline, 1958 , Uropterygius versutus Bussing, 1991 , and Uropterygius xenodontus McCosker & Smith, 1997 . The absence of a branchial pore in U. hades sp. nov. can serve as the primary diagnostic characteristic to distinguish it from congeners. Uropterygius cyamommatus , U. genie , U. golanii , U. inornatus , and U. xenodontus each possess a single branchial pore, while U. versutus has two branchial pores. Uropterygius hades sp. nov. also has fewer vertebrae (117–122 total vertebrae) compared to U. cyamommatus (141–149), U. golanii (145–148), U. versutus (131–138), and U. xenodontus (152–157), but overlaps with U. genie (121–122) and U. inornatus (116–133). However, U. hades sp. nov. differs from U. genie and U. inornatus by having smaller eyes (5.0–7.2 % vs 10.4–11.4 % and 7.7–10.0 % of HL), a shorter tail (47.6–51.4 % vs 53.5–54.5 % and 52.4–54.5 % of TL), and different dentition (biserial maxillary teeth vs about 4 rows and uniserial). Refer to table 2 in Huang et al. (2023 b) and the references cited therein for more detailed comparisons.

Note on additional records of U. mactanensis .

During our survey at several Japanese museums, two specimens having one branchial pore on both sides of head, formerly identified as U. concolor , were found from the Kyushu University Museum (catalog numbers KYUM-PI 2591 and 2612) (Fig. 8 View Figure 8 ). Although we were unable to assess the genetic features of these specimens, they can be identified as U. mactanensis based on diagnostic characteristics (Table 1 View Table 1 ). They were collected from the shallow bottoms around two adjacent small reef crests, one located off Funaura and the other off the mouth of the Kura River on Iriomote Island. The collection sites feature coarse sandy areas with large patch reefs, while the shallower regions contain scattered small patches of seagrass. Several marine muraenid species were collected by the same series of tube traps, such as Echidna nebulosa ( Ahl, 1789) , Gymnothorax flavimarginatus ( Rüppell, 1830) , Gymnothorax javanicus ( Bleeker, 1859) , Gymnothorax thyrsoideus ( Richardson, 1845) , Gymnothorax zonipectis Seale, 1906 , and Scuticaria tigrina ( Lesson, 1828) .

The second author has examined most museum collections of “ U. concolor ” from Japanese waters, identifying the majority as U. hades sp. nov., with only two specimens identified as U. mactanensis . This implies the rarity of U. mactanensis in the Ryukyu Archipelago. As a rare case of confusion between the two species, the general information previously provided for Japanese “ U. concolor ” (e. g., Tachihara 2017) possibly refers solely to U. hades sp. nov. Many photos of “ U. concolor ” collected from the estuary of Iriomote Island can further support the identification of U. hades sp. nov. based on general appearance and the absence of branchial pores. These photos can be found on FishPix (https://fishpix.kahaku.go.jp/fishimage-e/) ( KPM-NR 275 , 3350, 20306, 42937, 42948, 42949, 42950), photographed by H. Senou and T. Suzuki.

Material examined.

• KYUM-PI 2591 (316 mm TL), off mouth of Kura River, Iriomote Island, Yaeyama Group, Ryukyu Islands, 1 November 2009, coll. A. Tawa • KYUM-PI 2612 (370 mm TL), off Funaura, Iriomote Island, Yaeyama Group, Ryukyu Islands, 5 November 2009, coll. A. Tawa.