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The present study contributes to the taxonomy of the family Sillaginidae, with comments on the distribution of its species in the Indian Ocean and an emphasis on the taxonomy and distribution of Sillago sihama. Thirty described and putative species with Indian Ocean distribution are listed, and a distribution range for each species is provided based on published data and results from the present study. A comprehensive phylogenetic analysis of the barcoding portion of the mitochondrial COI gene is provided together with three approaches for molecular species delimitation, which includes 44 to 47 genetic lineages (depending on the species delimitation approach used) in the family Sillaginidae, 33 of them applying to described species and also 8 putative species, formerly misidentified as S. sihama. Inclusion of specimens from South Africa, Iran, Pakistan, India, Bangladesh and the southern Red Sea (type locality) reveals one genetic lineage representing the true Sillago sihama. Distribution of the species is confined to the Red Sea and the Indian Ocean, and other records under the name S. sihama are based on misidentifications. Several undescribed species identified as S. sihama are distributed in the Indo-West Pacific region and closely resemble S. sihama, but are not identical with this species and can be identified as members of different evolutionary lineages. Two species, S. sihama and S. soringa, reported from Bangladesh, represent the easternmost record of both species. These two species are described in detail, including swimbladder morphology. The study also shows that specimens from India identified as Sillago ingenuua McKay, 1985 are nested within a lineage previously referred to as S. ingenuua A, but are different from the lineage S. ingenuua B, representing a confirmed record of the clade S. ingenuua in the northern Indian Ocean. Comments on misidentifications of S. sihama from the Indian Ocean and western Pacific are provided. Furthermore, we propose that Sillago erythraea should be resurrected from its synonymy with S. sihama. As Sillago suezensis is identical with the former species, it becomes a junior synonym of S. erythraea.

A new species of Trimma is described from the Red Sea along the Saudi Arabian coast. Specimens and/or photographs of this species are available from the Egyptian Red Sea to Eritrea. These specimens, formerly identified as T. taylori, differ from all other samples from the Indo-Pacific currently identified as T. taylori in having 9 and 89 dorsal- and anal-fin rays respectively (vs. usually 10 and 10 rays), 13 pectoral-fin rays (vs. usually 14 rays), and cycloid scales covering the entire predorsal region from the upper base of the pectoral fin anterior to a convex line posterodorsally to just lateral to the base of the sixth first dorsal-fin spine (vs. predorsal region mostly or entirely covered with ctenoid scales). In addition, specimens from the Red Sea form a monophyletic lineage in a Maximum Likelihood analysis of the COI gene. In this tree, the new species is the sister group to a clade composed of three lineages. One is composed of specimens from the Maldives, which is the sister group of a single available specimen from the Seychelles. These two together are the sister group of specimens of a widespread western Pacific clade.

The gobiid species, Fusigobius humerosus sp. nov., is described based on 12 type and 18 non-type specimens collected from the Red Sea and Gulf of Aden. The new species can be distinguished from congeners by a combination of meristic and morphometric characters. The new species was formerly misidentified with F. humeralis: both are characterised by a semitranslucent body; head and body with numerous small dusky orange-yellow spots; a round black spot in humeral region just above base of pectoral fin; and a black spot subequal to pupil diameter at midbase of the caudal fin. However, Fusigobius humerosus sp. nov. differs from F. humeralis by scales on side of nape not extending forward to above posterior margin of preopercle (vs. scales variably extending forward to between above posterior preopercular margin and orbit); first dorsal-fin spine longest (vs. second and third dorsal-fin spines longest); shorter upper jaw; shorter anal-fin spine; and posterior nostril about halfway between orbit and anterior nostril (vs. posterior nostril closer to orbit). The most complete description of the genus Fusigobius is provided. In phylogenetic analyses of publicly available sequences of the barcoding portion of the mitochondrial cytochrome oxidase subunit I (COI) gene, sequences derived from the new species form a separate and well-divergent monophyletic lineage. The resulting COI gene tree further suggests that the new Fusigobius species is phylogenetically most closely related to F. humeralis which forms its sister species in the maximum likelihood tree. Molecular species delimitation of available Fusigobius COI barcodes shows that 19 or 20 hypothetical divergent evolutionary lineages can be deduced depending on the analytical approach (ABGD = 19 and bPTP = 20), indicating a potentially higher taxonomic richness than the presently acknowledged 11 valid species. However, the assignment of available species names for some lineages remains uncertain, highlighting the need for an additional integrative taxonomic research on this genus.

New data based on multigene phylogenetic analyses using the COI, 16S, and cytb genes and subsequent molecular species delimitation revealed that the mugilid genus Chelon contains 11 species. Of these, two species, Chelon sp. A and Chelon sp. B, remained unidentified in previous studies. While Chelon sp. B seemingly is a close relative to C. dumerili (Steindachner, 1870), no more detailed information were provided for Chelon sp. A which is present along the east coast of South Africa. Genetic analyses performed in this study, revealed that specimens from the Arabian/Persian Gulf and the Red Sea are nested within one genetic lineage alongside Chelon sp. A. Morphological, morphometric, and meristic analyses of specimens from all three areas demonstrated that they belong to Chelon persicus Senou, Randall & Okyiama, 1995. Chelon persicus was originally described in the genus Chelon but was later placed either in the genus Liza or Planiliza. However, results presented herein confirm its placement in Chelon and its distribution range is extended in the Western Indian Ocean from the type locality (Arabian/Persian Gulf) west to the Red Sea and south to South Africa. Further, the uncertain validity of the recently described Chelon caeruleus Deef, 2018 from the Mediterranean Sea and a previously proposed generic character distinguishing Chelon from Planiliza and Parachelon, the shape of the paired postzygapophyses of the second vertebra, are briefly discussed.

The monocle bream Scolopsis vosmeri species complex is revised. Three species in the complex are recognized: Scolopsis vosmeri (Bloch, 1792), widespread in the Indo-West Pacific, from the northern Indian Ocean (Pakistan, western India, Sri Lanka, Bay of Bengal, and the Andaman Sea, but not recorded from the Red Sea or Arabian Gulf, east African coast or Madagascar) to western Indonesia and Borneo; S. japonica (Bloch, 1793), restricted to the western Pacific Ocean from western Indonesia and north-western Australia east to the Philippines and north to southern Japan; and S. curite Cuvier, 1815, widespread from the western to the eastern Indian Ocean, including the Red Sea and Arabian Gulf. All three species are similar morphologically, and have been confused taxonomically, but phylogenetic analysis of the COI barcoding region shows they are evolutionarily divergent. The three species are redescribed in detail and characters found to distinguish them. Scolopsis vosmeri is easily distinguished from S. japonica and S. curite in having a white band along the side of the body; having a black spot on most body scales (versus greenish yellow spot in S. japonica and S. curite); in lacking a distinct black spot (sometimes a small and faint spot present) on the upper pectoral-fin base (versus small black wedge-shaped spot present in S. japonica and S. curite); caudal peduncle whitish in live individuals (versus caudal peduncle usually yellowish in S. japonica and S. curite); and pelvic and anal fins crimson to orange-red (versus yellow in S. japonica and S. curite). Scolopsis japonica and S. curite are indistinguishable by color pattern but differ in the degree of spination on the preopercular margin. Neotypes are designated for Scolopsis japonica and S. curite. Nomenclatural problems, including validity of the genus Scolopsis, are discussed. We regard Scolopsis curite Cuvier, 1815 as a valid binomial name and thus the type species of Scolopsis Cuvier, 1814 by subsequent monotypy.