Species Diversity 23: 253–262 25 November 2018 DOI: 10.12782/specdiv.23.253

Revision of in (: ) Described by de Beaufort (1912), with a First Record of Sicyopterus longifilis from Japan

Ken Maeda1,3 and Toshifumi Saeki2 1 Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna, Okinawa 904-0495, Japan E-mail: [email protected] 2 Rivus, 2-13-14-203 Oyama, Ginowan, Okinawa 901-2223, Japan 3 Corresponding author (Received 17 April 2018; Accepted 15 June 2018)

Amphidromous gobies of Sicyopterus (Gobiidae: Sicydiinae) are distributed in tropical, subtropical, and temperate streams in the Indo-Pacific region. Two species, Sicyopterus japonicus (Tanaka, 1909) and (Pallas, 1770), are known from Japan. In the present study, two specimens of an additional species were collected in Okinawa Is- land, in southern Japan. We compared morphologies of the type series of Sicyopterus longifilis de Beaufort, 1912 and Sicyo- pterus brevis de Beaufort, 1912 collected in Indonesia, with the specimens from Okinawa Island to revise the of these species and to identify the Okinawan specimens. Syntypes of S. longifilis and S. brevis share many characters, includ- ing a unique mouth morphology. Although fin morphologies, tooth number, and the shape of the urogenital papilla differ between S. longifilis and S. brevis syntypes, these amount to normal sexual dimorphism of sicydiine gobies. De Beaufort collected his specimens at the same locality on the same date. We conclude that the syntypes of S. longifilis and S. brevis are actually males and females of same species. Therefore, they are subjective synonyms, and we give precedence to the name S. longifilis as the first reviser under Article 24.2 of the International Code of Zoological Nomenclature (International Com- mission on Zoological Nomenclature 1999). The two specimens from Okinawa Island were identified asS. longifilis and this is the first record of this species from Japan. Key Words: Sicyopterus, Sicydiinae, Okinawa, taxonomy, synonym, first record.

in Japan (S. japonicus and S. lagocephalus; see Nakabo 2002, Introduction 2013), 13 species are known from the Philippines and In- donesia (Keith et al. 2015a, b). Given the dispersal capacity Amphidromous gobies of the subfamily Sicydiinae are of this , it would not be surprising if other Sicyopterus mainly found in insular streams in the Indo-Pacific and species are found in Japan. One of the reasons that only two Atlantic oceans, and have a marine pelagic larval phase species have been recorded in Japan is the difficulty of iden- (Keith and Lord 2011). Sicyopterus Gill, 1860 is composed tifying members of this genus, since its taxonomy is not well of 27 species that are distributed widely from Comoros, in understood. Most Japanese researchers and fish hobbyists the western Indian Ocean to Hawaii and French Polynesia, believe that Japanese Sicyopterus is composed only of these in the central Pacific Ocean (Keith et al. 2015a, b). It con- two species, and this mindset may have discouraged addi- tains the particularly widespread species Sicyopterus lago- tional investigations. cephalus (Pallas, 1770) distributed throughout nearly the In 2013, on Okinawa Island in the Ryukyu Archipelago of entire range of the genus excluding some marginal regions, southern Japan, we collected two specimens of Sicyopterus such as Madagascar, central Japan, Hawaii, Rapa, and the that could not be identified as eitherS. japonicus or S. lago- Marquesas Islands (Watson et al. 2000; Keith et al. 2015b). cephalus. Mouth structure is one of key characters for dis- This genus also includes species having a particularly long tinguishing species in this genus (Herre 1927; Allen 1991). pelagic larval duration [4–9 months in Sicyopterus japonicus The upper lips of the two Okinawan specimens lack a me- (Tanaka, 1909) and S. lagocephalus] (Iida et al. 2009). It has dian cleft, but have a lateral cleft on each side of the lip. This been suggested that larvae of Sicyopterus have great disper- feature is shared among several species, including Sicyo- sal ability and that they can be transported even to distant pterus longifilis de Beaufort, 1912 and Sicyopterus brevis de islands (Zink et al. 1996; Iida et al. 2008, 2010; Lord et al. Beaufort, 1912. However, diagnostic characters of these two 2012). In , another diverse genus in the same sub- species were insufficient to identify our Okinawan mate- family, seven species have so far been recorded in Japan and rial. Therefore, in the present study we investigated the type records of rare species are considered to have arisen from series of S. longifilis and S. brevis to revise their taxonomy. larval transportation from Southeast Asia by ocean currents Here we identify the Okinawan specimens and report them (Maeda et al. 2012a; Maeda and Saeki 2013; Maeda 2014). as a newly recorded species from Japan. While only two species of Sicyopterus have been recorded

© 2018 The Japanese Society of Systematic Zoology 254 K. Maeda and T. Saeki

fins. First and second dorsal- and anal-fin lengths were mea- Materials and Methods sured from the origin of each fin to the farthest point when the fin was adpressed. Caudal-fin length was measured as Measurements and counts were taken from the left sides the length of the central ray of the caudal fin. The interval of the fish. Measurements were made point-to-point to the between the first and second dorsal-fin bases was measured nearest 0.1 mm using a vernier caliper or a divider under from the posterior end of the first dorsal-fin membrane to a stereomicroscope, and were expressed as a percentage of the second dorsal-fin origin. The length from the anus to standard length (SL). Measurements and counts followed the anal fin was measured from the center of the anus to the Nakabo (2002), with the following modifications: body anal-fin origin. Scales in longitudinal series were counted depths were measured at the origins of the pelvic and anal from the middle of the posterior end of the hypurals to be-

Fig. 1. Syntypes of Sicyopterus longifilis de Beaufort, 1912 (ZMA 112562; A, 74.7 mm SL; B, 38.0 mm SL) and syntypes of Sicyopterus brevis de Beaufort, 1912 (ZMA 110981; C, 35.7 mm SL; D, 35.6 mm SL) (photo by K. Maeda). Sicyopterus described by de Beaufort (1912) 255 hind the pectoral-fin base. Scales in transverse series were Sicyopterus longifilis de Beaufort, 1912 counted along a diagonal line extending posteriorly and [New Japanese name: Gizagiza-bouzu-haze] ventrally from the first scale anterior to the second dorsal (Figs 1, 2A, B, 3A, B, 4, 5, 6A, B; Tables 1–4) fin, including one scale on the dorsal midline and another scale at the anal-fin base. Circumpeduncular scales were Sicyopterus longifilis de Beaufort, 1912: 140 (type locality: counted along the circumference of the narrowest point of Seram, Indonesia); de Beaufort 1913: 146; Koumans 1953: the caudal peduncle in a zigzag manner. Predorsal scales 232; Zhou and Gao 2011: 327; Keith et al. 2015b: 110. were counted on the dorsal midline from the origin of the Sicyopterus brevis de Beaufort, 1912: 141 [type locality: first dorsal fin forward to the occipital region. Dentition Seram, Indonesia; invalid, precedence given to S. longifilis terms follow Watson (2008). Symbolic codes used to repre- (see Discussion)]; de Beaufort 1913: 147; Koumans 1953: sent collections and institutions follow Sabaj (2016). 233; Keith et al. 2015b: 82. Sicyopterus lacrymosus Herre, 1927: 303 (type locality: Luzon, Philippines).

Table 1. Counts and measurement of specimens of Sicyopterus longifilis examined in the present study.

Catalog number ZMA 112562 ZMA 110981 URM-P 48275, 48276 Type status Syntypes of S. longifilis Syntypes of S. brevis Non-type specimens Locality Seram Seram Okinawa Number and sex 2 males 2 females 2 females Standard length (mm) 38.0–74.7 35.6–35.7 36.6–57.6 Counts Dorsal-fin rays VI-I,10 VI-I,10–11 VI-I,10 A rays I,10 I,10 I,10

P1 rays 20 20–21 20 Branched rays in C 15* 16* 15 Segmented rays in C 17 17–18 17 Scales in longitudinal series 55–57 49–55 54–56 Scales in transverse series 18 18–19 17 Circumpeduncular scales 28 25–29 26–27 Predorsal scales 15–19 16 18–20 Dentary symphyseal teeth 6–8 3 2–5 Measurements as % of standard length Head length 25.0–25.2 25.8–26.9 23.8–25.4 Snout length 11.3–11.6 11.0–11.8 10.7–11.1 Eye diameter 4.1–5.3 5.3–5.9 4.2–4.6 Postorbital length of head 11.6–12.4 11.5–11.8 11.2–12.2 Upper-jaw length 11.3–11.9 12.9 10.7–11.3

Body depth at P2 origin 17.1–18.3 16.9–18.5 16.4–17.7 Body depth at A origin 19.0–19.2 20.2–21.0 18.3–19.8 Depth at caudal peduncle 12.9–13.5 12.9–13.4 13.1–13.9 Length of caudal peduncle 19.2–19.8 19.3–19.9 19.4–21.3 Predorsal length 31.2–34.2 36.0–36.7 34.4–34.9

Length of D1 base 21.0–21.1 22.5 20.5–21.9

D1 length 44.2–58.5 23.0–26.1 27.8–35.2

Length of longest spine of D1 40.3–54.5 22.8–24.1 19.7–25.7

Interval between D1 and D2 bases 0–0.8 0.6 0.8–1.0

Length of D2 base 27.1–30.5 28.0–28.1 27.3–28.8

D2 length 43.7–50.2 35.1–37.8 35.2–38.4

Length of longest ray of D2 18.7–27.0 14.6–16.0 14.2–14.4 Preanal length 51.6–51.7 51.7–54.3 51.6–53.6 Length of A base 28.2–30.0 24.7–25.5 25.1–26.2 A length 40.5–43.5 32.3–33.1 33.6–35.9 Length of longest ray of A 13.7–16.2 11.5–12.6 11.5–12.0 Length from anus to A 2.6–3.2 3.1 3.3–3.8

Length of longest ray of P1 22.6–22.9 17.4–19.6 18.9–20.2 C length 27.9–28.6 24.4 21.4–23.8

D1, first dorsal fin;2 D , second dorsal fin; A, anal fin; C, caudal fin;1 P , pectoral fin; 2P , pelvic fin. Values with an asterisk are based on one specimen (broken in other specimen). 256 K. Maeda and T. Saeki

Fig. 2. Specimens of Sicyopterus from Okinawa Island, Japan, immediately after fixation. A, S. longifilis (URM-P 48276, female, 57.6 mm SL); B, S. longifilis (URM-P 48275, female, 36.6 mm SL); C, S. lagocephalus (URM-P 48260, female, 30.2 mm SL); D, S. japonicus (URM-P 48267, female, 59.3 mm SL) (photo by K. Maeda).

Sicyopterus panayensis Herre, 1927: 313 (type locality: 95.6 mm in total length), upper course of Tubah River, West Panay, Philippines). Seram, Indonesia, 27 February 1910, coll. L. F. de Beaufort Sicyopterus sp.: Lin 2007: 76. [Although de Beaufort (1912) wrote that he described this Sicyopterus sp. 1: Zhou and Gao 2011: 329. species from three specimens (49–97 mm in total length), Material examined. Syntypes of Sicyopterus longifi- currently only two specimens are available (Nijssen et al. lis: ZMA 112562, 2 males (38.0 and 74.7 mm SL; 48.6 and 1982)]. Syntypes of Sicyopterus brevis: ZMA 110981, 2 Sicyopterus described by de Beaufort (1912) 257 females (35.6 and 35.7 mm SL), upper course of Tubah River, West Seram, Indonesia, 27 February 1910, coll. L. F. de Beaufort. Non-type specimens from Okinawa, Japan: URM-P 48275, female (36.6 mm SL), a stream on the east- ern slope of Okinawa Island, 18 June 2013, coll. K. Maeda; URM-P 48276, female (57.6 mm SL), a stream on the west- ern slope of Okinawa Island, 28 June 2013, coll. T. Saeki. Diagnosis. Upper lip without median cleft, but with a lateral cleft on each side of lip; margin of upper lip between lateral clefts minutely serrated. Without tubercle behind median cleft. Ridge beneath the upper lip only with feeble papillae. Premaxillary teeth tricuspid. First dorsal-fin spines, especially second to fifth spines, long and filamentous in males. Posterior tip of first dorsal fin often exceeding base of last soft ray of second dorsal fin in males. Second to fourth spines of first dorsal fin in females somewhat elongate, but the tip of fin not extending to middle of second dorsal-fin base. Membranes notched between spines in female. Second dorsal fin usually with one spine and ten soft rays. Caudal fin with 17–18 (usually 17) segmented rays, including 15–16 Fig. 3. Mouth structures (in ventral view) of Sicyopterus longifilis (A, URM-P 48275; B, URM-P 48276), S. lagocephalus (C, URM-P branched rays. Pectoral fin with 20–21 rays. Scales in lon- 48257), and S. japonicus (D, URM-P 48267). MC, median cleft; LC, gitudinal series 49–57. Scales on nape and occipital region lateral cleft; TM, tubercle immediately behind the median cleft; RU, considerably smaller than scales on lateral sides of body. ridge beneath the upper lip. Description of syntypes of Sicyopterus longifilis. Two males (Fig. 1A, B; Table 1). Body elongate, cylindrical ante- (1913). Although pigmentation is somewhat indistinct due riorly and somewhat compressed posteriorly. Snout round to over a century of preservation, major markings are vis- and protruding beyond upper lip. Anterior naris short and ible in the syntypes: two brown Y-shaped bars laterally on tubular, posterior naris not tubular. Mouth inferior with body below second dorsal-fin base, followed by two brown upper jaw projecting beyond lower jaw. Upper lip without oblique bars laterally on caudal peduncle. Dusky brown median cleft, but with a lateral cleft slightly posterior to the triangular bar below eye. One indistinct brown blotch on middle of each side of the lip. Margin of upper lip minutely middle of membrane between third and fourth spines of serrated between lateral clefts. Premaxillary teeth fine and first dorsal fin. Dusky brown triangular marking on middle tricuspid. Dentary with six or eight canine-like symphy- of pectoral fin. Proximal part of pelvic fin brown in smaller seal teeth and a row of horizontal teeth enclosed in a thick, specimen. No distinct markings on second dorsal, anal, and fleshy sheath. First dorsal fin with six spines; spines elon- caudal fins. gate and filamentous (third spine longest) and posterior- Description of syntypes of Sicyopterus brevis. Two fe- most point of first dorsal fin (tip of third spine) extending males (Fig. 1C, D; Table 1). Morphologies corresponding to to the base of the eighth soft ray of the second dorsal fin in syntypes of S. longifilis, but having fewer dentary symphy- the smaller specimen (38.0 mm SL) and exceeding the base seal teeth (3 vs. 6 or 8 in S. longifilis), shorter spines on first of the last soft ray of the second dorsal fin in the larger one dorsal fin (posteriormost point of first dorsal fin extending (74.7 mm SL). Second dorsal fin with one spine and ten soft to base of spine or second soft ray of second dorsal fin vs. rays; fifth or sixth soft ray longest. Anal fin with one spine extending to or exceeding posterior part of second dorsal and ten soft rays; ninth soft ray longest. Caudal fin round- fin), second spine longest in first dorsal fin (vs. third spine), ed, with 17 segmented rays, including 15 branched rays. anterior rays longer in second dorsal and anal fins (vs. mid- Pectoral fin with 20 rays. Pelvic fins joined to form a strong dle or posterior rays longest), smaller first and second dor- cup-like disk with fleshy frenum. Occipital region (poste- sal, anal, caudal, and pectoral fins (vs. larger fins), rounded rior three-fourths) and body scaled, but pectoral-fin bases square urogenital papilla with slightly concave posterior naked. Ctenoid scales covering lateral and dorsal sides of margin (vs. rounded), and no distinct markings on body body. Scales on nape and occipital region cycloid and con- and fins (vs. some markings visible). siderably smaller than scales on lateral sides of body. Belly Description of non-type specimens from Okina- covered with cycloid scales. Anteriormost several scales wa. Two females (Fig. 2A, B, 3A, B, 4, 5, 6A, B; Table 1). on side of body (behind pectoral-fin base) cycloid. Cycloid Morphologies correspond to syntypes of S. brevis. Some ad- scales also occurring on first and second dorsal-fin bases, ditional characters which were not examined in the type se- anal-fin base, caudal-fin base, and proximal part of caudal ries of S. longifilis and S. brevis are described below. Second fin. Scales in longitudinal series 55 or 57; scales in transverse to fourth spines of first dorsal fin elongate (second spine series 18; circumpeduncular scales 28; predorsal scales 15 longest) and membranes deeply notched between second or 19. Urogenital papilla rounded. A drawing of S. longifilis and third, third and fourth, and fourth and fifth spines. Ce- (probably one of the syntypes) was provided by de Beaufort phalic sensory pore system A′, B, C, D(S), F, H, L′, M′, N, 258 K. Maeda and T. Saeki and O′ (Fig. 4). Oculoscapular canal not interrupted. Pre- laterally on caudal peduncle. First dorsal fin translucent opercular canal with three pores (M′, N, and O′). Cutane- with gray mottling on posterior part. Second dorsal fin ous sensory papillae developed over dorsal, lateral, and ven- translucent with gray mottling on proximal three fourths tral surface of head (Fig. 4). and with a pale gray line on distal margin. Anal fin trans- In preservative, dorsal and lateral background yellow- lucent with a submarginal gray line. Caudal fin translucent ish brown, ventral side cream. Triangular black marking with subdorsal and subventral pale gray lines; pale gray extending from ventral margin of eye to posterior end of spots on proximal two thirds of middle rays. Pectoral fin mouth. Two dusky brown Y-shape bars laterally on body gray, but dorsal and ventral parts translucent in larger speci- below second-dorsal-fin base, followed by two oblique bars men; pectoral fin translucent and only proximal part gray in the smaller specimen. Pelvic fin translucent. Color in life variable (Figs 5, 6A, B and field observa- tions). Dorsal and lateral background brown, ventral side whitish. Seven dusky brown blotches on dorsal side from posterior part of occipital region to caudal peduncle, ante- rior blotches somewhat indefinite, third to fifth ones sub- divided. Dorsal and lateral side of head mottled with small dusky brown markings. Dusky brown longitudinal stripe extending from tip of snout to below eye and to dorsal part of pectoral fin base, stripe continuing along lateral midline of body. Four dusky brown blotches along lateral midline of posterior part of body. Triangular black marking below eye sometimes highlighted. Markings of head and body often became indistinct (Fig. 5C). Dorsal, anal, and caudal Fig. 4. Arrangement of cephalic sensory pores and cutaneous fins translucent to yellowish or orange; markings similar to sensory papillae in Sicyopterus longifilis (URM-P 48276). C and those of preserved specimens. Distal parts of second to fifth D(S) are dorsal. AN, anterior naris; PN, posterior naris. spines of first dorsal fin pale orange to bluish white. Anal fin

Fig. 5. Underwater photographs of Sicyopterus longifilis females (A and B, URM-P 48276, C and D, URM-P 48275) on Okinawa Island. A, 28 June 2013; B, 27 June 2013; C and D, 3 June 2013 (photo by T. Saeki). Sicyopterus described by de Beaufort (1912) 259 with bluish-white edge. Narrow bluish-white lines dorsally the same as that of the S. longifilis syntypes. We conclude along subdorsal gray line and ventrally along subventral that the author mistook males and females of a single spe- gray line of caudal fin. Dorsal and ventral parts of pectoral cies as different species, describing the male specimens fin with orange tint; gray and cream dots on proximal part. as S. longifilis and female specimens as S. brevis. There are Pelvic fin translucent. many examples in which males and females of single sicy- Occurrences and habitats in Okinawa. This taxon diine species were formerly regarded as different species is very rare. In addition to the two individuals collected in [e.g., concolor (Gill, 1860) and L. seminudus Gün- 2013 (described above), one individual was observed in July, ther, 1880; Microsicydium atropurpureum Herre, 1927 and 2014 (not collected). These three specimens were found in M. formosum Herre, 1927 (see Maciolek 1977; Maeda et al. different streams, although detailed localities are not shown 2012b)]. Therefore, we consider S. longifilis and S. brevis to here due to the conservation perspective. Two of them are be synonyms. Because these two names were published on on the eastern slope and the other is on the western slope the same date in the same work, we give precedence to the of the island. These three sites are located from 0.4–1.3 km name Sicyopterus longifilis as the first reviser under Article from the upper limit of the estuary, respectively, and all sites 24.2 of the International Code of Zoological Nomenclature are lower than 10 m a.s.l. They were observed with two con- (International Commission on Zoological Nomenclature geners, Sicyopterus lagocephalus and Sicyopterus japonicus, 1999). some other amphidromous gobioids, including Stiphodon Sicyopterus longifilis shares a distinctive upper lip mor- percnopterygionus Watson and Chen, 1998, Awaous mela- phology (without median cleft but with a lateral cleft on nocephalus (Bleeker, 1849), and Rhinogobius nagoyae Jordan each side of the lip) not only with S. brevis, but also with and Seale, 1906, and the diadromous Kuhlia marginata (Cu- several other species: S. pugnans (Ogilvie-Grant, 1884) from vier in Cuvier and Valenciennes, 1829). Savaii, Samoa, S. lacrymosus Herre, 1927 from northern Luzon, Philippines, S. panayensis Herre, 1927 from Panay, Philippines, S. calliochromus Keith, Allen, and Lord, 2012 Discussion from Papua, Indonesia, and S. squamosissimus Keith, Lord, Busson, Sauri, Hubert, and Hadiaty, 2015 from Java, Indo- Revision of species described by de Beaufort nesia. Although Herre (1927) stated that the upper lip of his (1912). De Beaufort (1912) described S. longifilis and S. new species, S. lacrymosus, is entire (i.e., without a cleft), brevis as new species with four other new goby species from Koumans (1940), who reexamined nine syntypes of S. lac- streams in West Seram and the reef of Saonek, a small island rymosus, reported that they actually have a feeble cleft on to the south of Waigeo, in Indonesia. The next year, he re- each side and concluded that the types agreed fully with S. described these two species with a drawing of S. longifilis longifilis. Koumans (1953) regarded S. lacrymosus as a junior (see de Beaufort 1913). The significant differences between synonym of S. longifilis. Keith et al. (2015b) included both S. S. longifilis and S. brevis, based on these descriptions, are panayensis and S. lacrymosus among synonyms of S. longifi- fin morphologies (S. longifilis having larger first and sec- lis. Type specimens of S. lacrymosus and S. panayensis were ond dorsal and pectoral fins). The enormous development destroyed at the Bureau of Science in Manila during World of filamentous spines in the first dorsal fin of S. longifilis War II (Pietsch and Anderson 1997; Kottelat 2013). Based seemed to have drawn de Beaufort’s attention. We examined on descriptions in Herre (1927) and Koumans (1940, 1953), the syntypes of these two nominal species and confirmed we agree with Keith et al. (2015b) who listed S. lacrymosus the differences in fin morphology above, but we failed to and S. panayensis as junior synonyms of S. longifilis, because find any other significant differences except number of den- there are no significant morphological differences between tary symphyseal teeth (6–8 in S. longifilis vs. 3 in S. brevis), them. the shape of urogenital papilla, and some additional differ- Sicyopterus sp. in Lin (2007: 76) and Sicyopterus sp. 1 in ences in fin morphology: shapes of second dorsal and anal Zhou and Gao (2011: 329) are also identified as S. longifilis, fins (middle or posterior rays longest in S. longifilis vs. an- based on the mouth and fin morphologies and color of the terior rays longest in S. brevis) and the size of caudal fin (S. body and fins of the fishes in photographs shown in these longifilis having larger fins). All of these differences in fin books. morphology, tooth number, and shape of the urogenital pa- Sicyopterus pugnans differs from S. longifilis by having bi- pilla are generally seen between males and females of sub- cuspid teeth on the premaxilla (Ogilvie-Grant 1884; family Sicydiinae, as typical sexual dimorphism (Watson et and Meguro 1979) (vs. tricuspid in S. longifilis) as well as by al. 2000; Maeda et al. 2012a, b, 2015; Maeda and Tan 2013; its unique coloration (e.g., drop-like black marking below Maeda 2014; Maeda and Palla 2015). the eye vs. triangular mark in S. longifilis). Sicyopterus squa- The syntypes of S. longifilis are males and those of S. mosissimus differs from S. longifilis by having more scales in brevis are females. All were collected by de Beaufort at the the longitudinal and transverse series and along the predor- same locality on the same date (February 27th, 1910). De sal midline (Keith et al. 2015a). Sicyopterus calliochromus Beaufort (1912) stated that the syntypes of S. brevis were differs from S. longifilis by having fewer branched rays in the collected on February 27th, 1911, but this must be an error caudal fin (13vs . 14–16) and the distinctive gold and black because the collections were made in 1909–1910 (de Beau- striped pattern of males (Keith et al. 2012). fort 1912). The correct date must be February 27th, 1910, Identification of Japanese species of Sicyopterus. Two 260 K. Maeda and T. Saeki

Fig. 6. Underwater photographs of females of Sicyopterus longifilis and Sicyopterus lagocephalus on Okinawa Island. A, Sicyopterus longifilis (URM-P 48276), 27 June 2013; B, S. lagocephalus (front) and S. longifilis (behind; URM-P 48276), 28 June 2013; C, S. lagocephalus, 16 Octo- ber 2006; D, S. lagocephalus, 21 December 2007 (A and B, photo by T. Saeki; C and D, photo by K. Maeda). specimens collected from Okinawa Island (URM-P 48275 D). Sicyopterus longifilis is easily distinguished from these and 48276) are identified as S. longifilis, because their mor- two species based on mouth structure, as it lacks a median phologies corresponded well to the syntypes of S. brevis, cleft on the upper lip, and it also lacks a tubercle behind the which taxon is now a junior synonym of S. longifilis. We median cleft. The ridge beneath the upper lip has only feeble propose a new Japanese name for this fish, “Gizagiza-bou- papillae (Fig. 3A, B). zu-haze” for the specimens collected from Okinawa. It is Although the mouth structure is very useful to identify derived from serrated (“gizagiza” in Japanese) margin of the S. longifilis, it is difficult to observe in situ, unless a high- upper lip. “Bouzu-haze” means sicydiine goby. quality close-up photograph is taken (Fig. 6A). However, S. Sicyopterus longifilis is known from Indonesia (Seram, longifilis is still distinguishable from the much more abun- Babar, Ambon) (de Beaufort 1912; Koumans 1930), Philip- dant S. japonicus and S. lagocephalus, even without relying pines (Luzon, Panay, Negros, and Mindanao) (Herre 1927), upon the mouth structure. The body color of S. longifilis fe- Papua New Guinea, Solomon Islands (Keith et al. 2015b), males is similar to that of S. lagocephalus females, but dif- Taiwan (Lin 2007; Zhou and Gao 2011), and southern Japan fers in having seven, poorly defined dusky blotches on the (Okinawa) (present study). This is the first record of this dorsal side from the posterior part of the occipital region species from Japan. Okinawa Island is the northernmost to the caudal peduncle (vs. eight, more distinct blotches in known habitat for S. longifilis, but it is very rare on this is- S. lagocephalus; Fig. 6B, C), and the lateral blotches are also land. more indefinite (vs. seven clear blotches aligned along the Two species, Sicyopterus japonicus and S. lagocephalus lateral midline of the body in S. lagocephalus; Fig. 6B, C). had previously been known in Japan (Nakabo 2002, 2013), Sicyopterus japonicus is distinguished from other taxa by and they are common in Okinawan streams. These two spe- having 7–11 well-defined diagonal bands on the body (the cies share a characteristic mouth structure: the upper lip anterior ones extending from the dorsum postero-ventrally has a deep median cleft and a lateral cleft slightly posterior and the posterior ones extending from the dorsum antero- to the middle of each side of the lip. It has a prominent tu- ventrally; Fig. 2D). However, since the body color of these bercle immediately behind the median cleft and the ridge three species is quite variable (Figs 5, 6), it is necessary to beneath the upper lip has a row of protuberances (Fig. 3C, carefully monitor them and to understand the range of vari- Sicyopterus described by de Beaufort (1912) 261

Table 2. Counts of soft rays in the second dorsal fin of Sicyopter- of similar size to the lateral scales). us longifilis, Sicyopterus japonicus, and Sicyopterus lagocephalus. Comparative material. Sicyopterus japonicus: URM-P 9 10 11 48265, male (67.3 mm SL), Okinawa Island, 7 June 2013; Sicyopterus longifilis — 5 1 URM-P 48266, juvenile (35.2 mm SL), Okinawa Island, 7 Sicyopterus japonicus 1 13 — June 2013; URM-P 48267, female (59.3 mm SL), Okina- Sicyopterus lagocephalus — — 13 wa Island, 17 May 2014; URM-P 48268, female (69.0 mm SL), Okinawa Island, 17 May 2014; URM-P 48269, female (91.3 mm SL), Okinawa Island, 17 May 2014; URM-P 48270, Table 3. Pectoral-fin ray counts of Sicyopterus longifilis, Sicyopter- female (73.5 mm SL), Okinawa Island, 17 May 2014; URM-P us japonicus, and Sicyopterus lagocephalus. 48272, female (45.0 mm SL), Okinawa Island, 5 June 2014; URM-P 48273, male (64.4 mm SL), Okinawa Island, 5 June 17 18 19 20 21 2014; URM-P 48274, male (61.5 mm SL), Okinawa Island, Sicyopterus longifilis — — — 5 1 5 June 2014; URM-P 48734, female (90.8 mm SL), Okina- Sicyopterus japonicus 1 13 — — — wa Island, 30 April 2016; URM-P 48735, 1 male (63.4 mm Sicyopterus lagocephalus — — 8 5 — SL), Okinawa Island, 30 April 2016; URM-P 48736, male (92.0 mm SL), Okinawa Island, 11 June 2017; URM-P Table 4. Counts of branched rays in the caudal fin of Sicyopterus 48737, male (99.7 mm SL), Okinawa Island, 11 June 2017; longifilis, Sicyopterus japonicus, and Sicyopterus lagocephalus. URM-P 48738, female (81.7 mm SL), Okinawa Island, 11 June 2017. Sicyopterus lagocephalus: URM-P 48255, male 13 14 15 16 (47.5 mm SL), Okinawa Island, 10 November 2008; URM-P Sicyopterus longifilis — — 3 1 48256, male (48.6 mm SL), Okinawa Island, 10 Novem- Sicyopterus japonicus 4 7 3 — ber 2008; URM-P 48257, male (40.3 mm SL), Okinawa Is- Sicyopterus lagocephalus 2 11 — — land, 14 September 2009; URM-P 48258, male (34.2 mm SL), Okinawa Island, 11 October 2012; URM-P 48259, fe- ation of each species. Although we did not observe live male male (34.9 mm SL), Okinawa Island, 8 June 2013; URM-P S. longifilis, Lin (2007), Zhou and Gao (2011), and Keith et 48260, female (30.2 mm SL), Okinawa Island, 18 June 2013; al. (2015b) provided some images of S. longifilis males. Ac- URM-P 48261, female (52.6 mm SL), Okinawa Island, 12 cording to these, the basic markings of the males are similar December 2013; URM-P 48262, male (38.3 mm SL), Oki- to those of females, and males can be distinguished from S. nawa Island, 5 September 2014; URM-P 48263, female lagocephalus and S. japonicus males by same characteristics (40.6 mm SL), Okinawa Island, 1 October 2014; URM-P as the females. Males display characteristic nuptial colors. 48264, female (41.1 mm SL), Okinawa Island, 17 October Nuptial male S. longifilis display blue-green or silver on the 2014; URM-P 48731, male (57.4 mm SL), Okinawa Island, sides of the body, while S. lagocephalus usually has light blue 20 April 2016; URM-P 48732, male (50.2 mm SL), Okinawa on the sides, deep blue on the venter, and whitish on dorsal Island, 20 April 2016; URM-P 48733, male (48.2 mm SL), sides of the body, and S. japonicus never displays blue or sil- Okinawa Island, 20 April 2016. ver. Morphology of the first dorsal fin is also a useful char- acter. The second to fourth spines of the first dorsal fin of S. longifilis females are elongate and membranes between the Acknowledgments spines are deeply notched. The spines of males are quite long and filamentous. Although spines of males and females of S. We are grateful to Ronald de Ruiter (RMNH) for his kind lagocephalus and S. japonicus are also often elongate (espe- support of K. Maeda during his investigation of specimens cially in larger males), the first dorsal fin of these two spe- at RMNH. We wish to thank Steven D. Aird (OIST) for edit- cies is triangular or falcate (vs. palmate in S. longifilis). Still, ing the manuscript, Philippe Keith and Clara Lord (MNHN) it should be noted that spines of small individuals are not for valuable information, and Nori Satoh and members elongate in all species. of Marine Genomics Unit (OIST) for their kind support If the fish is captured, identification can be verified by the of our study. This study was supported by OIST and JSPS following characters, in addition to mouth structure. KAKENHI Grant Numbers 24780200 and 16K07492. 1) Using combined fin-ray counts in the second dorsal fin

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