taxonID	type	description	language	source
3E3587D3FFCA3333FBB1FECAFBDCFE35.taxon	description	Figures 1 A – C, 2 A & B, 3, 8 B, Table 2 Atherina sihama Fabricius in Niebuhr (ex Forsskål), 1775: 70 (Red Sea, Yemen, Al-Luhayya). Northern whiting; Sand smelt; Silver sillago	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFCA3333FBB1FECAFBDCFE35.taxon	materials_examined	Materials examined. Bangladesh: FEL _ OUC uncat. [tissue sample M 8191 – M 8193], 3 specimens, 88.7 – 140.8 mm standard length (SL), Maheshkhali, 21.77 ° N, 91.89 ° E, August 2019; FL _ JNU uncat. [MA 12038 – MA 12051], 14 specimens, 77.0 – 100.2 mm SL, Maheshkhali, January 2020; FL _ JNU uncat. [SM 112101 – SM 112107], 7 specimens, 112.4 – 159.0 mm SL, St. Martin’s Island, 20.61 ° N, 92.32 ° E, November 2021; additional 40 specimens, 76.6 – 110.3 mm SL, Maheshkhali, January 2020; 7 specimens, 63.3 – 143.5 mm SL, Cox’s Bazar (21.45 ° N, 91.96 ° E), November 2019. southern Red Sea: HUJF 19716, 184.0 mm SL, Eritrea, photograph; KAUMM 462 [KAU 12 - 006], 182.0 mm SL, Saudi Arabia, off Jizan, 15 February 2012; KAUMM 67 [KAU 12 - 789], 124.0 mm SL, Saudi Arabia, off Jizan, 29 February 2012; KAUMM 67 [KAU 12 - 789], 112.0 mm SL, Saudi Arabia, off Jizan, 01 March 2012; SMF 35900 [KAU 14 - 301], 195.0 mm SL, Saudi Arabia, off Jizan, 01 November 2014; SMF 35911 [KAU 14 - 351], 135.0 mm SL, Saudi Arabia, off Jizan, 04 November 2014. Comparative material: Sillago erythraea: SMF 35017 [KAU 12 - 790 & 791], 2, 128.0 – 134.0 mm SL, southern Red Sea, Saudi Arabia, off Jizan, 29 February 2012; KAUMM 468, 120 mm SL, southern Red Sea, Saudi Arabia, off Jizan, 31 October 2014. Sillago mengjialensis: FEL _ OUC 142378, holotype, 98 mm SL, Bangladesh, Cox’s Bazar. Sillago muktijoddhai: FEL _ OUC 142377, holotype, 92 mm SL, Bangladesh, Cox’s Bazar. Sillago cf. sihama 2: ZJOU _ FEBL 021131, 131.0 mm SL, China, Fujian, Zhangzhou, photograph.	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFCA3333FBB1FECAFBDCFE35.taxon	diagnosis	Diagnosis: Sillago sihama is distinguished by dorsal-fin rays XI + I, 20 – 23; anal-fin rays II, 21 – 23; 66 – 74 scales in the lateral line; 4 – 5 scales above the lateral line; 3 – 4 + 8 – 9 gill rakers on the first arch; 12 – 15 (mostly 14) abdominal, 5 – 10 (mostly 8) modified, 11 – 16 (mostly 13) caudal and 32 – 35 (mostly 35) total vertebrae. The body is brownish dorsally, silver ventrally; area between posterior nostril and dorsoanterior edge of orbit unpigmented; first dorsal fin with black pigment on first two membranes at spine tips; anal fin lacking black dots. The swimbladder is long with two anterior extensions, two posterior extensions without a lacuna at the base; the anterolateral extension of the swimbladder extends into the anterior short blind tubule and posterior one kinked, long and complex, and 10 – 11 lateral processes. The general body shape is shown in Figure 1 A – C. Counts and measurements are given in Table 2. Frequency distribution for meristic counts is given in Table 3. Color of fresh specimens (Fig. 1 A & B): The body is unmarked, brownish, silvery gray or silvery tan dorsally, silver on sides and ventrally. Area between posterior nostril and dorsoanterior edge of orbit unpigmented. First dorsal fin with some dusky pigment on the membranes, first two membranes much darker at spine tips; membranes of the second dorsal fin with dusky pigment adjacent anteriorly to each ray. The anal fin is light yellowish to whitish without black dots, with a white margin along anterior one-third of the fin. The caudal fin is light yellowish, usually blackish along dorsal and ventral edges of each lobe. Pectoral and pelvic fins are light yellowish. Swimbladder (Fig. 2 A & B): The swimbladder is long. Two anterior extensions are divided and end on each side of the basioccipital over the auditory capsule. An anterolateral extension originates anteriorly on both sides of the swimbladder and then bifurcates into anterior and posterior subextensions. The anterior subextensions are short, simple blind tubules, but the posterior one is kinky, long and complex, extending along the abdominal wall and terminating near the bases of two posterior extensions. The entire lateral surface of the main body of the swimbladder has 10 – 11 robust and horn-like lateral processes (anterior 4 – 5 stout and horn-like, posterior 6 – 7 small and triangular) and penetrate the musculature. Posterior sub-extensions of the swimbladder are ventrally adjacent to the lateral processes but not interconnected with each other. Two posterior tapering extensions of the swimbladder extend into the caudal region. Bases of the two posterior extensions are adherent and two posterior extensions are well-knit, without a lacuna in between. A single duct-like process arises from the ventral surface of the swimbladder, and extends to the urogenital opening. The duct-like process originates anteriorly at the termination of the swimbladder and anterior to the base of two posterior extensions. A sub-extension is attached to the sanguineous vesicle near the vertebrae.	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFCA3333FBB1FECAFBDCFE35.taxon	distribution	Distribution: Sillago sihama, originally described from the southern Red Sea (Yemen), is widely distributed in the Indian Ocean, sampled from the southern Red Sea (Eritrea and Saudi Arabia), Arabian Sea (western India, Pakistan), northeastern Arabian Gulf (Hormozgan, Iran), South Africa (Mlalazi Estuary, Tugela Bank and Mhlathuze Estuary), and Bay of Bengal, Bangladesh (Maheshkhali, Cox’s Bazar and St. Martin’s Island) (Lakra et al. 2011; Golani et al. 2013; Bogorodsky et al. 2014; Steinke et al. 2016; Cheng et al. 2020; Divya et al. 2021 (as S. intermedius); Amir et al. 2022; Afrand et al. 2023; present study) (Fig. 3).	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFCA3333FBB1FECAFBDCFE35.taxon	discussion	Remarks: Habib & Islam (2020) listed S. sihama from Bangladesh based on six sources, but all these publications lack descriptions of collected material. Later, Ahmed et al. (2021) included specimens under the name S. sihama in their phylogenetic analysis, but further study revealed that this material represents another species, namely Sillago muktijoddhai Gao & Saha, 2022. Accordingly, S. sihama is reported as the first confirmed, easternmost record from Bangladesh in the present study. Unfortunately, there is no published literature on the structure of the swimbladder for S. sihama samples from India, Pakistan, Iran and South Africa. However, there were marked differences in the swimbladder between specimens from Bangladesh (Fig. 2 A & B) and Eritrea based on available published literature (Golani et al. 2013; Fig. 2 C in present study). According to Golani et al. (2013), the swimbladder of Sillago sihama (Eritrea) lacks an anterior subextension of the anterolateral extension, and the two posterior tapering extensions are separated from each other. The posterior sub-extensions of the anterolateral extension are smooth but differ from those in S. sihama (Bangladesh). These differences include the presence of an anterior subextension of the anterolateral extension, two posterior extensions joined to each other, and each posterior subextension of the anterolateral extension is a complex. Previously Kaga (2013) raised this question with detailed comments and stated that Golani et al. (2013) must have overlooked anterior sub-extensions of the anterolateral extension. Moreover, these authors did not provide any swimbladder photographs (just schematic drawings) and did not indicate which specimens were examined for swimbladder morphology. Therefore, swimbladder morphology described in the present study is applicable to the true S. sihama and can be useful for comparison with undescribed species in future.	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFD73331FBB1FA86FEABF848.taxon	description	Figures 4 & 5, Table 2	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFD73331FBB1FA86FEABF848.taxon	materials_examined	Materials examined. Bangladesh: FL _ JNU uncat. [SS 22015, SS 22035, SS 22042, SS 22043 and SS 22044], 5 specimens, 81.8 – 101.2 mm SL, St. Martin’s Island, 20.62 ° N, 92.32 ° E, February 2020; additional 25 specimens, 69.6 – 102.2 mm SL, St. Martin’s Island, February 2020. India: 4 specimens, 116.6 – 123.9 mm SL, Chennai, 13.29 ° N, 80.32 ° E, December 2019; F 7734 / 2, holotype; F 7735 / 2, 4 paratypes, 123.0 – 153.0 mm TL, Visakhapatnam, photograph. Comparative material: Sillago vincenti: FL _ JNU uncat. [CH 12191 – CH 121910], 10 specimens, 141.8 – 220.3 mm SL, December 2019, India, Chennai. Sillaginopsis domina: FEL _ OUC uncat. [tissue sample 142276, 142284, and 142293], 3 specimens, Bangladesh, Cox’s Bazar, October 2018; FL _ JNU uncat. [PP 121910, PP 121915 and PP 121916], 3 specimens, 180 – 195 mm SL, December 2019, Bangladesh, Patharghata.	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFD73331FBB1FA86FEABF848.taxon	diagnosis	Diagnosis: Sillago soringa is differentiated by dorsal-fin rays X – XI + I, 20 – 22; anal-fin rays II, 20 – 22; 68 – 72 lateral line scales; 4 – 5 scales above the lateral line; 4 + 8 – 9 = 12 – 13 gill rakers on the first arch; 12 – 14 (mostly 13) abdominal, 6 – 7 (mostly 7) modified, 11 – 14 (mostly 13) caudal, and 32 – 34 (mostly 33) total vertebrae; swimbladder long with a single anterior extension and a single posterior extension, short anterolateral extension and ten lateral processes. The general body shape is shown in Figure 4 A. Counts and measurements are given in Table 2. Color of fresh specimens (Fig. 4 A): Body brown dorsally, whitish ventrally. Dorsal fins hyaline dusted with black dots, with dots on second dorsal fin arranged in two longitudinal rows. Anal fin light yellowish to whitish dusted with black dots. Caudal fin mainly hyaline, with dusky pigment posteriorly. Pectoral and pelvic fins hyaline. Swimbladder (Fig. 4 B & C): The swimbladder with one anterior extension projecting forward, anterolateral extension curved backward along each side for a short distance, only one posterior extension, and ten lateral processes. The duct-like process is visible.	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFD73331FBB1FA86FEABF848.taxon	distribution	Distribution: Sillago soringa is distributed in the northern Indian Ocean, including the southeast coast of India (Jayasankar 1991), the east coast of India (McKay 1992) and presently, the southernmost part of Bangladesh (St. Martin’s Island) (Fig. 5). Comparison: Meristics, morphometric measurements and structure of the swimbladder of S. soringa from Bangladesh match the previous description of S. soringa from India by Dutt & Sujatha (1982) (Table 2). Frequency distribution for meristic counts is given in Table 3. Often Sillago mengjialensis Gao, Baki & Saha, 2022, S. muktijoddhai, and S. soringa were found as a mixed group, so identification should be made based on body color and swimbladder morphology. As S. soringa resembles S. sihama but is difficult to differentiate without observation of the swimbladder (Dutt & Sujatha 1982; McKay 1992), it was most probably misidentified as S. sihama in Bangladesh. The species can be distinguished from S. sihama by having 33 vertebrae (versus 35), black dots on the anal fin and its swimbladder structure (a single posterior extension in S. soringa versus two posterior extensions in S. sihama). Sillaginopsis domina (Cuvier, 1816) can be differentiated easily from S. soringa by a very elongated second dorsal-fin spine, small eyes and absence of a swimbladder. Sillago soringa is also similar to and can be confused with S. vincenti McKay, 1980, S. boutani Pellegrin, 1905 and S. asiatica McKay, 1982 but these three species have not yet been recorded from Bangladesh. However, S. soringa can be distinguished from these three species by combination of several characters, e. g., absence of black dots on body below lateral line, presence of black dots on the anal fin, number of vertebrae (usually 33 versus 34 – 38 in other three species) and swimbladder structure (Table 4). Among these four species, S. soringa is more similar to S. asiatica, but the anterolateral extension of the swimbladder is much shorter in S. soringa than in S. asiatica. Differences in the structure of the swimbladder among S. soringa, S. asiatica, S. vincenti and S. boutani are shown in Figure 4 C – F.	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFD23336FBB1FC1EFDBAF833.taxon	description	Figure 6 A & B	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFD23336FBB1FC1EFDBAF833.taxon	materials_examined	Materials examined. India: FL _ JNU uncat. [CH 121911, CH 121915 – CH 121918, CH 121920, CH 121922 and CH 121923], 9 specimens, 122.9 – 141.4 mm SL, Chennai, December 2019. Comparative material: Sillago ingenuua: FEL _ OUC 176002, 122.5 mm SL, China, Fujian, Dongshan. Brief description: Dorsal-fin rays XI + I, 17; anal-fin rays II, 16 – 17; scales in lateral line 66 – 71; scale rows above lateral line 4 – 5; vertebrae: 13 – 14 + 9 – 10 + 9 – 12 = 32 – 34. Swimbladder with a short median anterior extension, a single posterior extension and about 5 small, pointed anterolateral projections. Body color is pale yellowish brown. The general body shape and swimbladder are shown in Figure 6 A – C. Geographical distribution: According to the phylogenetic analysis and species delimitation approaches Sillago ingenuua is divided into two (ASAP and PTP) or three (ABGD) genetic lineages (Fig. 7): Sillago ingenuua A from the Gulf of Thailand (type locality), Indonesia, Vietnam, China, and Malaysia (BOLD number MUHD 029 - 15, private sequences as S. sihama); S. ingenuua B from Western Australia, eastern Australia (BOLD number FOAL 889 - 10) and Taiwan (both lineages were recognized by Gao et al. 2023); and S. ingenuua from Chennai, India. Sillago ingenuua was also reported from Sri Lanka (De Bruin et al. 1994) but no genetic material was available from that area.	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
3E3587D3FFD23336FBB1FC1EFDBAF833.taxon	discussion	Remarks: Two separate lineages with 4.9 % and 6.9 % genetic divergence were previously detected in S. ingenuua, based on COI sequences and 13 concatenated protein coding gene sequences in the absence of significant morphological differences (Tikochinski et al. 2013; Cheng et al. 2020; Gao et al. 2023). One is Sillago ingenuua A from China, Vietnam, Thailand and Indonesia, and Malaysia, another is Sillago ingenuua B from Australia and Taiwan. Because there is insufficient distance (1.6 %) between S. ingenuua from India and S. ingenuua A, the former was included as the member of that lineage. In this study, we first report S. ingenuua A from the Indian Ocean, specimens of which form a monophyletic group within S. ingenuua A and are recognized as a potential separate species by the ABGD approach for species delimitation only, whereas PTP and ASAP do not suggest a separation from their western Pacific Ocean conspecifics. In this species, an integrative taxonomic study is needed to resolve the actual species boundaries.	en	Saha, Shilpi, Bogorodsky, Sergey V., Baki, Mohammad Abdul, Gao, Tianxiang, Mckay, Roland J., Alpermann, Tilman J., Song, Na (2024): Assessment of the diversity of the family Sillaginidae in the Indian Ocean with emphasis on the taxonomic identity of Sillago sihama. Zootaxa 5493 (5): 451-485, DOI: 10.11646/zootaxa.5493.5.1, URL: http://dx.doi.org/10.11646/zootaxa.5493.5.1
