Uropterygius fasciolatus ( Regan, 1909 )

Koeda, Keita & Hibino, Yusuke, 2017, First Japanese Record of Uropterygius fasciolatus (Muraenidae: Uropterygiinae) Collected from Yonaguni-jima Island, Ryukyu Archipelago, Species Diversity 22, pp. 207-211 : 207-211

Uropterygius fasciolatus ( Regan, 1909) [New standard Japanese name: Murakumo-kikaiutsubo] ( Figs 1–3 ; Table 1)

Gymnomuraena fasciolata Regan 1909: 438 (type locality: Atafu , Tokelau Islands).

Uropterygius fasciolatus: Myers 1999: 51 ( Palau and Kapingamarangi Atoll); Böhlke et al. 1999: 1654, 1657, fig. 37; Böhlke and Smith 2002: 158; Allen and Adrim 2003: 23 ( Indonesia); Allen and Erdmann 2012: 97, unnumbered fig. ( Indonesia, Papua New Guinea, Solomon Islands, Palau, Tokelau Islands, Phoenix Islands); Smith 2012: 36; Fricke et al. 2014: 21 ( Papua New Guinea).

Uropterygius goslinei McCosker and Randall, 1977: 167 , figs 3c, 5 (type locality: Kayangel Atoll , Palau; Papua New Guinea, Solomon Islands).

Material examined. Two specimens from Yonagunijima island in the Yaeyama Islands, southern Ryukyu Archipelago, Okinawa, Japan: KAUM –I . 88909, 304.0 mm TL, KAUM –I. 88910, 441.4 mm TL, Umabana , 24°28′19″N, 122°57′57″E, 7 m depth, 5 July 2016, coll . K . Koeda.

Description. Counts and measurements are shown in Table 1. Body moderately elongate; body depth almost same throughout, depth at gill-opening 17.7–19.9 times in TL. Body laterally compressed throughout, its width at gill- opening 1.8–2.0 times in depth. Tail longer than body, preanal length 17.5–20.0 times in TL. HL 9.5–10.5 times in TL. Median fins restricted to end of tail, origins located between verticals through 116th and 117th vertebra. Gill-opening located in middle of body, oblique slit, its length longer than eye diameter ( Fig. 2 ).

Snout short, rounded. Anterior nostril tubular, located anterior tip of snout; posterior nostril tubular, located anterodorsal side of eye, tube longer than that of anterior nostril. Eyes located above middle mouth, with diameter 1.9– 2.6 times of snout; jaws subequal, not curved, and closing completely.

Teeth pointed, slightly recurved. Maxillary and mandibular teeth triserial with outer row teeth small, numerous and close-set, and inner row teeth large, widely-spaced ( Fig. 3 ). Inner and middle rows on maxilla forming zigzag-shape and line up densely at tip. Inner-row teeth on mandible largest anteriorly. Intermaxillary region crowded by a group of large fangs, separated from uniserial-vomerine-teeth row by a gap.

Head pores indistinct. One ethmoid pore ventrally on snout+two supraorbital pores anterodorsally on snout; four infraorbital pores and five mandibular pores along upper and lower lips. Two lateral-line pores located anterodosal side of gill opening ( Fig. 2 ); a minute series of rudimental lateral-line pores passing along the mid-body to the tail tip.

Coloration when fresh —Body and head light yellow in KAUM–I. 88909 and light brown in KAUM–I. 88910; irregular narrow dark crossbars partially reticulated often appearing incomplete; widely scattered faint white spots in KAUM–I. 88909. Posterior margin of tail bright yellow. Two distinct dark lines originating at posterior dorsal and ventral margins of eye in KAUM–I. 88909, and extending ca. 1.5 times of eye diameter ( Fig. 2 ); both lines branched at middle; upper line running posterodorsally, and lower running posteroventrally. Two dark lines present in KAUM–I. 88910, but faint and shorter than KAUM–I. 88909; lower line unbranched; both lines running posterodorsally.

Distribution. Uropterygius fasciolatus has been recorded from the following localities of the Pacific Ocean: Indonesia, Papua New Guinea, the Solomon Islands, Palau, Kapingamarangi Atoll, the Tokelau Islands, the Phoenix Islands ( Myers 1999; McCosker and Randall 1977; Allen and Erdmann 2012), and Yonaguni-jima island in Japan (present study). The two present specimens were collected from holes of hermatypic coral at 7 m depth located in a coral reef area.

Remarks. The present specimens from Yonaguni-jima island were identified as a species of the genus Uropterygius , being clearly distinguished from other genera by the following combination of characters: body moderately elongate, laterally compressed; trunk length shorter than tail length; median fins restricted to tail tip; jaws short, subequal and closing completely; eye located above middle of mouth; gill opening small and slit-like ( McCosker and Smith 1997).

Most morphometric values (e.g., preanal length 41.4– 43.7% TL vs. 43.4% TL; body depth at gill-opening 5.0–5.7% TL vs. 5.4% TL), pattern of head pores (two lateral-line pores), and body coloration (irregular narrow dark crossbars on body; two distinct dark lines originating at posterior dorsal and ventral margins of eye) for the present specimens closely resemble to those of the holotype of U. fasciolatus ( Table 1; Fig. 1 ). Therefore, the present specimens are identified as U. fasciolatus . However, the Yonaguni-jima island specimens differ slightly (more than 1% difference) in the following meristic and morphometric measurements from the holotype of U. fasciolatus : counts of vertebrae 130–131 (vs. 124 in holotype); body width at mid-anus 2.4–2.7% SL (vs. 3.4% SL); upper-jaw length 42.3–42.3% HL (vs. 44.5% HL); gill-opening length 9.0–11.7% HL (vs. 7.1% HL). More than 7 differences on the counts of vertebrae in single species have been shown in many species of genus Uropterygius ( Smith 2012) . In addition, these generally small differences in measurements may simply reflect the limited number of specimens available for study. The shape of the snout differed between the specimens from Yonaguni-jima island and the holotype, such as that snout to dorsal outline of the head are rounded in the former, but that the dorsal outline of the head is straight line and the tip of snout is more pointed in the latter. The difference in snout shape may reflect dehydration by long-term preservation in ethanol. In addition, the patterns of teeth rows on maxilla and mandible slightly differed between the present specimens and the holotype, such as inner and middle teeth rows of maxilla have three rows at the tip in the former, but are much randomly placed and do not make rows in the latter. Moreover, the patterns of dark lines behind the eye differ in each specimen: e.g., KAUM–I. 88909 has branched lower lines, but KAUM–I. 88910 and the holotype have unbranched ones; the lower line of KAUM–I. 88910 runs posterodorsally, but those of other two specimens run posteroventrally; the lower line of the holotype is long (ca. three times eye diameter), but are short in the two present specimens (ca. 1 or 1.5 times eye diameter). Although these differences in snout outline, teeth arrangements, and colorations are considerable, the differences herein are determined as intraspecific variations.

Uropterygius fasciolatus most closely resembles Uropterygius alboguttatus Smith, 1962 , Uropterygius kamar McCosker and Randall, 1977 , Uropterygius xanthopterus Bleeker, 1859 , sharing some characters such as having two lateralline pores ( Böhlke et al. 1999). However, only the present species has the irregular narrow dark crossbars on the body, and two distinct dark lines originating at the posterior dorsal and ventral margins of eye. Uropterygius fasciolatus has a unique color pattern compared with Japanese congeners. Within its congeners, U. fasciolatus shares the character of teeth arrangement with Uropterygius marmoratus (Lacepède, 1803) . However, the former species differs from the latter in having 124–131 total vertebrae (vs. 131–139), two lateral-line pores (vs. one), and irregular vertical bars on body (vs. brown mottling) ( McCosker and Randall 1977; Allen and Erdmann 2012; present study).

Uropterygius fasciolatus was described by Regan (1909) on the basis of a single specimen (BMNH 1877.2.24.84, 304.0 mm TL) collected from Atafu in the Tokelau Islands with some morphological description. Although McCosker and Randall (1977) described Uropterygius goslinei, Smith (1994) subsequently placed this species as a junior synonym of U. fasciolatus based on a personal communica- tion by J. E. McCosker. Böhlke and Smith (2002), Allen and Erdmann (2012), and Smith (2012) followed this opinion, but a comparative study of both species has never been presented. In our observations, most of morphological characters of the holotype of U. goslinei shown in McCosker and Randall (1977) are similar with those of the holotype and present specimens collected from Yonaguni-jima island of U. fasciolatus ( Table 1). In addition, the teeth arrangements of U. goslinei shown in McCosker and Randall (1977) were also similar as those of the holotype of U. fasciolatus . The patterns of teeth slightly differed between the holotype of U. fasciolatus and the paratype of U. goslinei (ANSP 117434) as shown in McCosker and Randall (1977), such as that intermaxillary and vomerine teeth are well separated in the former, but are much closer in the latter. However, the other paratype of U. goslinei (USNM 215282) has a similar teeth pattern with the holotype of U. fasciolatus and the Japanese specimens (S. Kimura pers. comm.). Therefore, these differences of teeth patterns are herein determined as intraspecific variations. Although McCosker and Randall (1977) described the distinct black stripes behind the eye and white spots on the body as the diagnostic characters of U. goslinei , intraspecific color variations are known in U. fasciolatus . On the basis of the similarity of counts, measurements, and teeth arrangements, and variation in head and body colorations, we herein reconfirm that U. goslinei is a junior synonym of U. fasciolatus , and the distributional information of U. goslinei from several publications are included into the distribution of U. fasciolatus in the present study.

As stated above, U. fasciolatus has not been previously recorded from Japanese waters, and the northernmost record of the species was hitherto from Palau (7°31′N, 134°35′E) ( Myers 1999). Therefore, the present specimens collected from Yonaguni-jima island represent the first record of U . fasciolatus from Japan, and the northernmost record of the species, with an approximately 2,200 km northwestward range extension.

A new standard Japanese name, “Murakumo-kikaiutsubo”, is herein proposed for the species, on the basis of one specimen (KAUM–I. 88909). The proposed species name is a combination of “murakumo” meaning “gathering clouds” in Japanese from the irregular narrow dark bars on body of the species, and “kikaiutsubo” meaning a fish of the subfamily Uropterygiinae in Japanese.

Comparative material: Uropterygius fasciolatus , holotype: BMNH 1877.2 . 24.84, 304.0 mm TL, Atafu (formerly Duke of York Island ) in the Tokelau Islands, 8°33′N, 172°30′E; Uropterygius goslinei , paratype, USNM 215282, 149.2 mm TL, Koror Island, Palau .

Figures

Fig. 1. Fresh specimen of Uropterygius fasciolatus (upper: KAUM–I. 88909, 304.0mm TL; middle: KAUM–I. 88910, 441.4mm TL) collect- ed from Yonaguni-jima island, Japan, and holotype (lower: BMNH 1877.2.24.84, 304.0mm TL) collected from Atafu in the Tokelau Islands.

Fig. 2. Illustration of head of Uropterygius fasciolatus collect- ed from Yonaguni-jima island, Japan (tupper: KAUM–I. 88909, 304.0mm TL; middle: KAUM–I. 88910, 441.4mm TL), and holotype (lower: BMNH 1877.2.24.84, 304.0mm TL). Open and solid arrows indicate gill opening and lateral-line pores, respectively.

Fig. 3. Illustration of teeth on maxilla (left) and mandible (right) in Uropterygius fasciolatus (KAUM–I. 88910, 441.4mm TL) collect- ed from Yonaguni-jima island, Japan.