Range extension of Blackstripe Lizardfish, Synodus nigrotaeniatus Allen, Erdmann & Peristiwady, 2017 (Actinopterygii, Aulopiformes, Synodontidae), from Jakarta Bay, Indonesia

. Three specimens (194.4–203.8 mm standard lengths) of the lizardfish Synodus nigrotaeniatus Allen, Erdmann & Peristiwady, 2017, collected from Jakarta Bay, western Indonesia, represent a significant range extension for the species, which was previously known from only six specimens collected in Lembeh Strait, North Sulawesi, eastern Indonesia. Morphological comparisons with available data from the type specimens and molecular data from the mitochondrial cytochrome oxidase subunit I (COI) gene are presented. The COI sequence data show a 4% genetic difference from the related Synodus sageneus Waite, 1905.


INTRODUCTION
The genus Synodus Scopoli, 1777 (Teleostei, Synodontidae) is characterized by having eight pelvic fin rays, with the innermost ones longer than the outermost, 8-11 anal fin rays, with the fin base length shorter than the dorsal-fin base (except Synodus nigrotaeniatus Allen, Erdmann &Peristiwady, 2017 andSynodus sageneus Waite, 1905), and the procurrent caudal-fin rays not covered by scales (Cressey 1981;Russell 1999).Synodus comprises 47 valid species, including 35 Indo-Pacific species, and six species each in the eastern Pacific and Atlantic oceans (Fricke et al. 2024).In Indonesian waters, the genus is currently known from 13 species (Allen and Adrim 2003;Allen and Erdmann 2012;Allen et al. 2017), although the recently described S. nigrotaeniatus has been reported only from the type locality in Lembeh Strait, North Sulawesi Province, eastern Indonesia (Allen et al. 2017).
Three lizardfish specimens were recently collected by local fishermen as bycatch from Jakarta Bay, western Indonesia, and subsequently identified as Blackstripe Lizardfish, S. nigrotaeniatus, represent the first record of the species from western Indonesian waters.Comparisons between the specimens with available data from the six type specimens of the species are provided, along with molecular data from the mitochondrial cytochrome oxidase subunit I (COI).

METHODS
Counts and measurements followed Allen et al. (2017).Standard length is expressed as SL.Vertebral numbers were counted from radiographs taken using the portable x-ray apparatus Collimax X-ray Collimator R-120 H. Sex was confirmed by dissection of the right side of the abdomen.Curatorial procedures for the specimens [deposited at the Museum Zoologicum Bogoriense, Indonesia (MZB)] followed Motomura and Ishikawa (2013).Tissue samples were collected from muscle and extracted following Chelex 10% protocols (Walsh et al. 1991).Extracted DNA was amplified by Polymerase Chain Reaction (PCR) targeting the cytochrome oxidase subunit 1 (COI) with forward primer JgLCO 5′-TITCIACI AAYCAYAARGAYATTGG-3′ and reverse primer JgHCO 5′-TAIACYTCIGGRTGICCRAARAAYCA3′ (Geller et al. 2013).The PCR reaction was carried out in 25 µL volumes, using 4 µL of DNA template.Each reaction included 12.5 µL MyTaqTM Red Mix (Bioline), 1 µL of each primer, and 6.5 µL ddH2O.The thermocycling profile included initial denaturation of 95 °C for 4 min, 40 cycles of 95 °C for 30 s, 50 °C for 30 s, and 72 °C for 1 min, with a final extension at 72°C for 10 min.The PCR reactions were checked on 1% agarose gel stained with Florosafe (1st BASE, Singapore), the results being visualized using a UV-transilluminator and documented with a digital camera.Amplicons were then sequenced using the Sanger Sequencing Platform.
Forward and reverse sequences were checked, cleaned, and aligned using MEGA X software (Kumar et al. 2018)  A phylogenetic tree was reconstructed using maximum-likelihood analysis, using the HKY+G+I parameter model with 1,000 bootstrap replicas to assess clade support.The maximum-likelihood model and genetic distances with Kimura-2 Parameter model between and within species were calculated with MEGA X (Kumar et al. 2018).
The COI gene sequences from the two samples acquired in this study (the first reported for S. nigrotaeniatus) were successfully amplified by PCR, the total lengths of the sequences are 657 base pairs (bp).The BLAST analysis (Figure 2) indicates a 96% percent similarity with S. sageneus; the genetic distance between S. nigrotaeniatus and all available species of Synodus ranging from 0.042-0.249(Table 2).

DISCUSSION
Since its original description by Allen et al. (2017), Synodus nigrotaeniatus has not been reported from any other locations, including the type locality.Therefore, the discovery of S. nigrotaeniatus from Jakarta Bay, approximately 2,200 km southwest of Lembeh Strait, Sulawesi Island (Figure 3), represents a significant range extension, and brings the total number of known examples of the species to nine specimens.
Synodus nigrotaeniatus is most similar to the Indo-West Pacific S. sageneus; these two species differ from all other Synodus species in having a relatively robust body with the eyes more dorsally directed, a more gradually angled snout profile, a long anal-fin base (its length greater than the dorsal-fin base), a greater number of anal-fin rays, a tiny adipose fin, and a prominent suborbital pore with surrounding fimbriae.However, S. nigrotaeniatus differs from S. sageneus in several meristic and morphometric characters, and color pattern (Allen et al. 2017).Several morphometric features (Table 1: body depths at the anal and pelvic fin origins, body width, orbit diameter, interorbital width, pre-pelvic fin length, anal-fin base length, and caudal, pectoral, and pelvic fin lengths) of the newly collected specimens were slightly outside (<1.5% of SL) the ranges of the type specimens of S. nigrotaeniatus reported by Allen et al. (2017).In addition, the only meristic differences between the latter and those from Jakarta Bay were dorsal fin ray (11-12 in the former vs. 12-13 in the latter) and lateral-line scale (47-49 vs. 49-50) numbers, both regarded here as intraspecific variation.
However, an inconsistency in the number of pectoral-fin rays was noted in the original description of the species, 11 being indicated in the diagnosis and 13 in the description (Allen et al. 2017).The present specimens suggest that the latter was, in fact, the correct number.
Dissection of the Jakarta Bay specimens (194.4-203.8mm SL) confirmed their status as mature females, each having an expanded gonad with relatively large eggs.
The molecular data from the COI gene indicated a clear distinction between S. nigrotaeniatus and S. sageneus, with 4% genetic difference (Table 2), which is equivalent to the percentage difference used to differentiate between many other related reef fish species, such as the Chrysiptera species complex (Allen et al. 2015(Allen et al. , 2017)).

Figure 2 .
Figure 2. Phylogenetic tree of Synodus nigrotaeniatus with maximum-likelihood (ML) topology generated from mtDNA COI gene.Numbers below major nodes indicate maximum likelihood bootstrap support for 1,000 replicates.

Table 1 .
Counts and measurements (expressed as percentages of standard length) of Synodus nigrotaeniatus.