THRISSINA ENCRASICHOLOIDES (ACTINOPTERYGII: CLUPEIFORMES: ENGRAULIDAE): FIRST RECORD FROM TAIWAN AND NORTHERNMOST RECORD OF THE SPECIES

first record and northernmost of the Abstract. Although four species of the engraulid genus Thrissina (often regarded as Thryssa ) have previously been recorded from waters around Taiwan, Thrissina encrasicholoides (Bleeker, 1852), known from the eastern Indian and western Pacific Oceans (north to the Philippines), has not been to date. However, two specimens (100.1 and 100.6 mm standard length) of T. encrasicholoides were collected from south-western Taiwan. Their morphology and fresh coloration are described, the former being largely consistent with previous descriptions of the species: short maxilla, its posterior tip blunt, slightly beyond anterior margin of preopercle; 14 or 17 keeled scutes; and one scute weakly developed and lacking a ventral edge projection, immediately behind the isthmus. The specimens represent the first record of the species from Taiwanese waters and the northernmost record of the species.


INTRODUCTION
Thrissina Jordan et Seale, 1925, an Indo-Pacific genus of marine and/or brackish water anchovies (Engraulidae), comprises 26 valid species (Whitehead et al. 1988, Wongratana et al. 1999, Kottelat 2013, Hata and Motomura 2019. Although the genus has long been treated as Thryssa Cuvier, 1829 (e.g., Whitehead et al. 1988;Wongratana et al. 1999), Kottelat (2013) pointed out that Thryssa was an incorrect subsequent spelling of Thrissa, and gave precedence to Thrissina over other available names for the genus. That determination is followed here.

RESULTS
Family ENGRAULIDAE Thrissina encrasicholoides (Bleeker, 1852) New Taiwanese name: 印尼稜鯷 (In-ni-ling-ti) ( Fig. 1; Tables 1, 2) Description. Counts and measurements expressed as percentages of SL, given in Tables 1 and 2. Body laterally compressed, rather elongate, deepest at dorsal-fin origin. Dorsal profile of head and body nearly straight, but gradually elevated from snout tip to dorsal-fin origin, thereafter gently lowering to uppermost point of caudal-fin base. Ventral profile of head and body slightly convex from lower-jaw tip to pelvic-fin insertion, nearly straight from pelvic-fin insertion to end of anal-fin base, slightly concave at caudal peduncle. Abdomen rounded, covered with incomplete series of scutes. One scute weakly developed, lacking ventral edge projection, immediately behind isthmus. Row of six or eight prepelvic scutes, each with sharp spine on ventral edge of body, anteriormost below mid-point of pectoral fin. Thereafter row of eight or nine postpelvic scutes, each with sharp spine, terminating just before anus. Anus just anterior to anal-fin origin. Caudal peduncle rather compressed. Snout tip pointed; snout length less than eye diameter. Mouth large, inferior, ventral to body axis, extending backward beyond posterior margin of eye. Lower jaw slender, shorter than upper jaw. Maxilla short, its posterior tip blunt, slightly beyond anterior margin of preopercle. Single row of small conical teeth on each jaw. Small conical teeth in patch on vomer. Teeth patches on palatines and endopterygoids. Small teeth patches on dorsal surface of hyoid bone. Eye large, round, covered with thin adipose eyelid, positioned laterally on head dorsal to horizontal through pectoral-fin insertion, visible in dorsal view. Pupil round. Orbit elliptical. Nostrils close to each other, anterior to orbit. Posterior margins of preopercle and opercle smooth. Subopercle with rounded posterior margin. Opercular membrane without serrations. Interorbital space flat, width less than eye diameter. Pseudobranchial filaments present, exposed, length of longest filament less than eye diameter. Gill rakers long, slender, rough, visible from side of head when mouth opened. Size of each asperitiy on gill rakers even. Isthmus muscle long, reaching anteriorly to posterior margin of gill membranes. Urohyal hidden by isthmus muscle (not visible without dissection). Gill membrane on each side joined distally, isthmus muscle mostly exposed (not covered by gill membrane). Scales cycloid, thin, deciduous except for ventral scutes, absent on head and fins. Scales on lateral surface of body with numerous vertical grooves. Lateral line absent. Dorsalfin origin posterior to vertical through base of last pelvicfin ray, slightly anterior to middle of body. Dorsal and anal fins each with minute first ray. Spine-like scute on dorsal-fin origin. Anal-fin origin posterior to posterior end of dorsal-fin base; posterior tip of depressed fin not reaching caudal-fin base. Uppermost pectoral-fin ray unbranched, not extended as filament. Pectoral fin inserted below lateral midline of body; posterior tip of fin not reaching vertical through pelvic-fin insertion. Pelvic fin shorter than pectoral fin, insertion anterior to vertical through dorsal-fin origin; posterior tip of depressed fin reaching to vertical through origin of tenth or eleventh dorsal-fin ray.
Coloration when fresh. Body uniformly whitish-silver, dorsum to upper part of lateral surface of body dark blue. Snout semi-transparent, melanophores scattered on dorsal surface. Fin rays of dorsal and caudal fins yellowish. Melanophores scattered on rays and membranes of dorsal and caudal fins. Pectoral, pelvic, and anal fins uniformly whitish, semi-transparent. Pupil and iris black and silver, respectively.
Coloration of preserved specimens. Body uniformly pale, upper part of body dark. Melanophores scattered on dorsal and caudal fins.

DISCUSSION
The Taiwanese specimens were assignable to the genus Thrissina, defined by Whitehead et al. (1988) and Wongratana et al. (1999) (as Thryssa) as having strongly keeled prepelvic-and postpelvic scutes on the ventral edge, a spine-like scute on the dorsal-fin origin, dorsal and anal fins with 14, and 30-33 rays, respectively, the uppermost pectoral-fin ray not extended as a filament, and small conical teeth on both jaws. Moreover, the two specimens were identified on the basis of the following combination of characters, which closely matched the diagnostic features of Thrissina encrasicholoides given by Nelson (1981), Whitehead et al. (1988) and Wongratana et al. (1999): short upper jaw, its posterior tip blunt, slightly beyond the anterior preopercle margin; body without a distinct black blotch; 14 or 17 keeled scutes on the abdomen; and one weakly developed scute lacking a ventral edge projection, immediately behind the isthmus.
Although T. encrasicholoides is most similar to Thrissina baelama (Forsskål, 1775), in sharing fewer (four to nine) prepelvic scutes and a short upper jaw (posterior tip not beyond anterior margin of preopercle), the latter is characterized by a lack of scutes immediately behind the isthmus and the posterior tip of the maxilla pointed (Nelson 1981, Whitehead et al. 1988, Wongratana et al. 1999. Thrissina encrasicholoides was described by Bleeker (1852) (as Engraulis encrasicholoides) based on specimens collected from Jakarta, Java, Indonesia.  Abbreviations: D-P1 (distance between dorsal-fin origin to pectoralfin insertion); D-P2 (distance between dorsal-fin origin to pelvic-fin insertion); D-A (distance between origins of dorsal-and anal fins); P1-P2 (distance between insertions of pectoral-and pelvic fins); P2-A (distance between pelvic-fin insertion to anal-fin origin).
Although treated as a junior synonym of T. baelama by some authors (e.g., Weber and de Beaufort 1913, Fowler 1941, Whitehead et al. 1966, Nelson (1981) confirmed the validity of the former after examining specimens collected from Sri Lanka, India (Vishakhapatnam), the Philippines, Indonesia, and Queensland. Nelson (1983) also regarded Engraulis duodecim, described by Cope (1867) from a specimen supposedly collected from Beasley's Point, New Jersey, USA, as a junior synonym of T. encrasicholoides, pointing out the erroneous collection locality. Thereafter, Krishnan and Mishra (1994) reported the species from the Andaman Islands (specimens deposited in the Marine Biological Station, Zoological Survey of India, Madras) and Fricke et al. (2014) reported a specimen (AMS I.16747-004) collected from Madang District, Papua New Guinea. Because there appear to be no further significant distribution records of T. encrasicholoides, the presently described specimens from south-western Taiwan are considered to represent the first record of the species from Taiwan and the northernmost records of the species.