Research Article Volume 13 Issue 2 - March 2021 DOI: 10.19080/OFOAJ.2021.13.555860 Oceanogr Fish Open Access J Copyright © All rights are reserved by Muhammad Iqbal Pormansyah 1 , Muhammad Iqbal 1 *, Syahputra Putra 3 , Arum Setiawan 3 , Indra Yustian 3 and Hilda Zulkifli 3 1 Faculty of Science, Sriwijaya University, Indonesia 2 Department of Agriculture and Livestock, Indonesia 3 Department of Biology, Sriwijaya University, Indonesia Submission: January 22, 2021; Published: March 11, 2021 Corresponding author: Muhammad Iqbal, Biology Program, Faculty of Science, Sriwijaya University, Jalan Padang Selasa 524, Palembang, Sumatera Selatan 30129, Indonesia Oceanogr Fish Open Access J 13(2): OFOAJ.MS.ID.555860 (2021) 001 Abstract During 2006-2017, we made a series of observations of Boleophthalmus pectinirostris on the east coast of South Sumatra province and Bangka island, Sumatra, Indonesia. This species is very similar to B. boddarti, in size, external morphological characters and behaviour. In this paper, we discuss the external morphological differences between B. pectinirostris and B. boddarti. Records of B. pectinirostris in southern Sumatra increase the known distribution range of this species 800 km southwards, indicating that this species was previously confused with B. boddarti in Indonesian waters. Keywords: Similar; Morphological characters; Oxudercidae; Boleophthalmus pectinirostris; Indonesia; Sumatra; Distribution Similar but Different: Differences Hitherto Overlooked between Boleophthalmus pectinirostris and B. boddarti (Teleostei: Oxudercinae) in Indonesian Waters Introduction The prospect of identifying gobies fills many people with more than a little consternation [1]. The systematics and phylogeny of the gobiies are acknowledged as being difficult, and the smaller gobiids, in particular, are often overlooked by collectors [2]. The external characters that are of most help in identifying gobies include the arrangement and shapes of the fins, the number of fin rays and soft fin spines, the number of branchiostegal rays (in the membrane under the gill cover), the extent of the gill opening, the kind of scales (cycloid or ctenoid) and their distribution on the body, the proportions of the head, the jaw shape and position of the jaw tips, the shape of the teeth and the arrangement of the lateral canals and sensory papillae on the head [1]. Some of them, the oxudercine gobies, are euryhaline fish that are typically found on tidal flats formed in creeks, estuaries, and coastal waters at low tide [3]. In a cladistic analysis of the Oxudercinae subfamily of the Gobiidae, based on osteological, eco-ethological and morphological characters [4], the three genera of oxudercine gobies (Boleophthalmus Valenciennes, 1837, Periophthalmus Bloch & Schneider, 1801, and Periophthalmodon Bleeker, 1874), were grouped in the same clade with the following shared characteristics: the abductor superficialis muscle of the pectoral fin is divided into two sections (presumably aiding terrestrial locomotion); and the neurocranial cavities are anteriorly enlarged, with a curved frontal interorbital bridge which overlaps with the ethmoid bones [4,5]. The species in these genera can move over land with considerable speed; and their eyes, placed on top of the head and capable of being elevated or retracted, are well adapted for vision in air [6]. With different degrees of taxonomic and gene sampling bias, molecular studies have provided phylogenetic reconstructions for oxudercine gobies that are inconsistent with morphological, osteological, and eco- ethological analyses [7,8]. Recent studies have found molecular evidence to support the