A checklist of ponyfishes ( Teleostei , Leiognathidae ) from Miyazaki Prefecture , east coast of Kyushu , southern Japan , with range extensions of three tropical species

A checklist is presented of ponyfish species (Teleostei, Leiognathidae) from the coast of Miyazaki Prefecture, eastern coast of Kyushu, in the warm temperate zone of Japan and in areas influenced by the warm Kuroshio Current. Fish collection surveys (autumn, October 2016 to winter, early 2017) recorded 9 species of the family, including 1 collected by previous authors. Records of 3 species, Gazza minuta (Bloch, 1795), Leiognathus equulus (Forsskål, 1775), and Leiognathus fasciatus (Lacepède, 1803), extended their distributional ranges northward by ca 150–500 km. These 3 species and 3 others are distributed mainly in the tropical zone, and, combined with previous records of leiognathid fishes along the coasts influenced by the Kuroshio Current in southern Japan, this study shows a continuous distribution pattern of these tropical species, suggesting that the east coast of Kyushu is also influenced by this warm current. Diagnostic features, color images, and voucher specimen data are provided for each species.


Introduction
Members of the family Leiognathidae (Teleostei, Perciformes), known as ponyfishes, are small, generally silvery fishes, most less than 15 cm in total length, but some reach nearly 25 cm.Most species form schools that may contain up to several hundred individuals.They are found near the bottom in shallow coastal waters, with several species entering brackish waters, especially estu-aries, and with a few ranging into fresh water.This family is widely distributed in the Indo-West Pacific region with most species occurring in tropical Southeast Asia (Allen and Erdmann 2012).Approximately 49 species in 9 genera are known (Woodland et al. 2001, Allen and Erdmann 2012, Kimura 2015, Nelson et al. 2016).Fourteen species in 7 genera are known from Japan (Senou 2013), and 11 of these are considered tropical species based on their distribution patterns (Nakabo 2013).
Miyazaki Prefecture is located on the south-east side of Kyushu, which is the southernmost main island of Japan, and has a long coast (latitudinally) that faces the Pacific Ocean.Offshore, the warm, strong Kuroshio Current flows from the south-west to the north-east (Fig. 1), and a number of tropical fishes have been reported at their northernmost extent of distribution in the prefecture (e.g.Miyamoto et al. 2011, Hayashida et al. 2012, Miki 2017, Miki et al. 2017).Comprehensive fish surveys of this region are needed to better understand the effects of the Kuroshio Current on marine fish diversity in relation to the known biogeography of the northwestern Pacific region.During our survey of the marine fish fauna of Miyazaki Prefecture, 9 species of leiognathids were collected and 3 of these species represent their northernmost records.We herein provide a list of leiognathid species of Miyazaki Prefecture based on voucher specimens, with their diagnostic features and color images.
Data collection.The collected specimens were fixed with 10% formalin and preserved in 70% ethanol.These materials were deposited in the fish collection of the Kanagawa Prefectural Museum of Natural History (KPM-NI) as vouchers for the present study.The identification and scientific names followed Senou (2013), Sparks and Chakrabarty (2015), and Suzuki and Kimura (2017).Counts and measurements followed Mochizuki and Hayashi (1989).Senou (2013) reviewed previous distribution records of members of the family Leiognathidae from Japanese waters and additional information was added by Endo (2012), Fujiwara and Motomura (2016), and Suzuki and Kimura (2017).The distribution of leiognathid species in Japanese waters followed these authors.Standard length (SL) was measured as the distance from the snout tip to the base of the caudal fin.Color photographs of the specimens were taken when fresh and deposited in the image data base of Kanagawa Prefectural Museum of Natural History (KPM-NR).Nakabo (2013) defined the biogeographic categories of fishes distributed in Japanese waters into 46 groups based on differences in distributional patterns.We followed his definitions for dividing each leiognathid species into its biogeographic category.Tropical species of the family have their northernmost limits along coasts of Japan that are influenced by the Kuroshio Current, and the distribution records of tropical species recorded in the present study are summarized in Table 1 and Figure 1.

Results
We recorded 464 individuals from 7 genera and 8 species from Miyazaki Prefecture.In addition to these species, we confirmed Leiognathus equulus by the reexamination of a specimen listed in a past study and from photographic material.Of these records, those of Gazza minuta (Bloch, 1785), L. equulus, and Leiognathus fasciatus (Lacepède, 1803) represent the northernmost records for the species.A list of all specimens examined, their digitized voucher numbers, and geographic coordinates are listed in the Appendix (Table A1).
Distribution.Deveximentum indicium is known from Japan, Taiwan, South China Sea, Philippines, Indonesia, New Guinea, and the Gulf of Thailand.In Japanese waters, this species is known from the coast of Konan City of Kochi Prefecture, northern and southern coasts of Miyazaki Prefecture, Uchinoura Bay (Pacific coast), and the coast of Minami-satsuma City, Kagoshima Prefecture (East China Sea) (Fig. 1, Table 1: Kimura et al. 2008a, Endo 2012, Senou 2013, Fujiwara and Motomura 2016, this study).
Remarks.Although Deveximentum indicium was first reported from Japan by Kimura et al. (2008a as Secutor indicius) from Uchinoura Bay, south-eastern Kyushu, 245 specimens (29.0-105.4mm SL) of the species were collected from the coasts of Miyazaki Prefecture throughout the present survey period.In addition to the large number of specimens, a wide range of sizes were observed.This species is known to attain about 100  mm SL (Kimura 2011), and therefore individuals from Miyazaki Prefecture are large enough to be mature.Furthermore, the largest specimen in this study (KPM-NI 42096, 105.4 mm SL) represents the maximum size from literature records in Japan.

Genus Equulites Fowler, 1904
Equulites popei (Whitley, 1932) Diagnosis.this species is characterized by the following combination of characters: slender body, its depth equal to or shorter than head length; mouth protruding downwards; small slender teeth on both jaws; anterior dorsolateral surface of body and breast completely scaled; anterior spinous dorsal fin without conspicuous black blotch (Senou 2013).
Distribution.Equulites popei is known from Japan, Philippines, Malaysia (Sabah), Thailand (Gulf of Thailand), Oman, the Red Sea including Suez Bay, the Mediterranean (immigrant from the Red Sea), and southern Mozambique.In Japanese waters, this species is known from the Noto Peninsula, Sea of Japan coast of Yamaguchi Prefecture, western coast of Kyushu (Sea of Japan coast), Sagami Bay to the southern part of eastern coast of Kyushu (Pacific coast), and Okinawa Island (Senou 2013, Suzuki andKimura 2017).
Remarks.Five specimens (35.6-65.5 mm SL) of E. popei were caught from the southern coast of Miyazaki Prefecture in December.
Distribution.Equulites rivulatus is known from Japan and the southern coast of Korean Peninsula.In Japanese waters, this species is known from the coast of Akita Prefecture to the southern part of western coast of Kyushu (Sea of Japan coast), the coast of Ibaraki Prefecture to the southern part of eastern coast of Kyushu, the Seto Inland Sea (Pacific coast), and the continental shelf of East China Sea (Senou 2013).Remarks.The present record of 106 specimens (34.0-103.1 mm SL) and frequency of catchment (over autumn-winter period) indicates that Gazza minuta is a common species along the coasts of Miyazaki Prefecture.Previously, the northernmost record of the species was Uchinoura Bay, southeastern coast of Kyushu (Fujiwara and Motomura 2016), and the present specimens of G. minuta from Kadogawa Bay extend the known distributional range of the species ca 150 km north-northeast from Uchinoura Bay.  ).However, this record did not provide any basis of identification nor mention its distribution range.We can confirm here that this specimen (Fig. 3B) is L. equulus.In addition to this specimen, a single individual photographed from Kadogawa Bay (KPM-NR 176728, Fig. 3A) was recorded in our study.Although the northernmost record of the species was previously Amami Island, the northern part of Ryukyu Islands (Senou 2013, Fujiwara andMotomura 2016), the present specimens of L. equulus from Kita-gawa river extend the known distribution range of the species ca 500 km northnortheastward from Amami Island.Diagnosis.This species is characterized by the following combination of characters: mouth protruding downwards; small slender teeth on both jaws; anterior dorsolateral surface of body completely naked; black blotch on nape (Senou 2013).

Leiognathus fasciatus
Distribution.Nuchequula nuchalis is known from Japan, the western and southern coasts of Korean Peninsula, Taiwan, and the coast of China.In Japanese waters, this species is known from the western coast of Aomori Prefecture to the southern part of the western coast of Kyushu (Sea of Japan coast), the eastern coast of Aomori Prefecture to the southern part of eastern coast of Kyushu, Seto Inland Sea, and Okinawa Island (Pacific coast) (Senou 2013).

Discussion
Our study is the second faunal survey of leiognathid fishes along the eastern coast of Kyushu.In the first survey, Fujiwara and Motomura (2016) reported 7 species, Deveximentum indicium, Equulites popei, Equulites rivulatus, Eubleekeria splendens, Gazza minuta, Nuchequula nuchalis, and Photopectoralis bindus, from Uchinoura Fishing Port, which is located ca 40 km southwest of Meitsu Fishing Port (Fig. 1).In addition to the 7 species reported by Fujiwara and Motomura (2016), we recorded 2 additional species, Leiognathus equulus and Leiognathus fasciatus, for the first time from the east coast of Kyushu, mainland of Japan, and the northernmost records for the 2 species.These facts suggest that the former 7 species are widely distributed in the eastern coast of Kyushu and the occurrence of the latter 2 species may be strays in the temperate zone of Japan.Nishimura (1992) proposed the following 7 areas in Japanese waters in his marine zoogeographical study: frigid zone, subarctic zone, cool temperate zone, intermediate temperate zone, warm temperate zone, subtropical zone, and tropical zone.According to his divisions, the coast of Miyazaki Prefecture is located in the warm temperate zone.On the other hand, Nakabo (2013) considered E. popei, E. rivulatus, and N. nuchalis to be temperate fishes, and the other leiognathid species were categorized as tropical fishes occurring mainly in the tropical zone.In other words, despite the coasts of Miyazaki Prefecture being located in the temperate zone, we recorded several tropical species of Leiognathidae, resulting in a continuous distribution pattern for those species in Japan along the Kuroshio Current (Table 1).
The Kuroshio Current, which flows from the eastern part of Philippines via the eastern part of Taiwan and along the Pacific coast of Japan, has a strong effect, transporting larvae and juveniles of many tropical fishes to temperate regions of Japan (Senou et al. 2006) (Fig. 1).The diverse leiognathid assemblage along the coast of the Miyazaki Prefecture probably reflects the influence of the current on the marine fish fauna of the eastern coast of Kyushu.
Most tropical fishes transported from the south to the mainland of Japan by the Kuroshio Current, cannot survive the winter nor mature due to the cooler water (Motomura 2012).While some tropical leiognathids were collected over the autumn to winter period and some of the individuals were large enough to be mature, these results do not definitively suggest that these species represent populations that persist over the entire winter.Recent catches of D. indicium and G. minuta along the coasts of Miyazaki Prefecture have rapidly increased (local fishermen, pers.comm.) and many individuals of these 2 tropical species were collected in almost every survey in our study.It is necessary to conduct a comprehensive ichthyofaunal survey along the eastern coast of Kyushu utilizing both qualitative and quantitative methods to construct baseline information to reveal relationships between marine fish diversity and physical environmental dynamics, such as the warm, strong current and climate change.

Figure 1 .
Figure 1.Map showing literature records based on vouchers (red numbers) and the sampling points of this study (blue numbers and letters)for tropical species of Leiognathidae along the Kuroshio Current (orange line) in southern Japan.The numbers and letters represent the following sites: 1, Sumiyo Bay, Amami Island; 2, southern part of Tanega-shima island; 3, northern part of Tanega-shima island; 4, Uchinoura Bay, Kagoshima Prefecture; 5, Kasasa Town, Kagoshima Prefecture; 6, southern part of Miyazaki Prefecture; 7, northern part of Miyazaki Prefecture; 8, Iburi, Tosa-shimizu City, Kochi Prefecture; 9, Urado Bay, Kochi Prefecture; 10, Konan City, Kochi Prefecture; A, B, collecting points to be landed in the Meitsu Fishing Port; C, collecting point to be landed in the Tomishima Fishing Port ; D, collecting point to be landed in the Kadogawa and Iorigawa fishing ports; E, collecting point to be landed in the Urashiro Fishing Port.