Anatomical insights into fish terrestrial locomotion: A study of barred mudskipper (Periophthalmus argentilineatus) fins based on µCT 3D reconstructions.

Mudskippers are a group of extant ray-finned fishes with an amphibious lifestyle and serve as exemplars for understanding the evolution of amphibious capabilities in teleosts. A comprehensive anatomical profile of both the soft and hard tissues within their propulsive fins is essential for advancing our understanding of terrestrial locomotor adaptations in fish. Despite the ecological significance of mudskippers, detailed data on their musculoskeletal anatomy remains limited. In the present research, we utilized contrast-enhanced high-resolution microcomputed tomography (µCT) imaging to investigate the barred mudskipper, Periophthalmus argentilineatus. This technique enabled detailed reconstruction and quantification of the morphological details of the pectoral, pelvic, and caudal fins of this terrestrial mudskipper, facilitating comparison with its aquatic relatives. Our findings reveal that P. argentilineatus has undergone complex musculoskeletal adaptations for terrestrial movement, including an increase in muscle complexity and muscle volume, as well as the development of specialized structures like aponeuroses for pectoral fin extension. Skeletal modifications are also evident, with features such as a reinforced shoulder-pelvic joint and thickened fin rays. These evolutionary modifications suggest biomechanically advanced fins capable of overcoming the gravitational challenges of terrestrial habitats, indicating a strong selective advantage for these features in land-based environments. The unique musculoskeletal modifications in the fins of mudskippers like P. argentilineatus, compared with their aquatic counterparts, mark a critical evolutionary shift toward terrestrial adaptations. This study not only sheds light on the specific anatomical changes facilitating this transition but also offers broader insights into the early evolutionary mechanisms of terrestrial locomotion, potentially mirroring the transformative journey from aquatic to terrestrial life in the lineage leading to tetrapods.

Heterochrony and the evolution of the longjaw mudsucker (Gobiidae, Teleostei).

Although longjaw mudsucker (Gillichthys mirabilis, Gobiidae) has been studied extensively for its ability to occupy low-oxygen environments, few studies have addressed the evolution of its exceptionally elongated jaws that extend posteriorly beyond the gill opening in large adults. In this study, the ontogeny of the maxillae of G. mirabilis, Gillichthys seta, and the out-group species Eucyclogobius newberryi was studied within the heterochrony framework using digitized landmarks and caliper measurements. The results show that the maxilla of both species of Gillichthys evolved via acceleration (increased growth rate) and that of G. mirabilis via hypermorphosis (continued growth to a larger body size); two forms of peramorphosis. This is in contrast to earlier studies that concluded that G. seta is paedomorphic. We were unable to confirm an earlier hypothesis of sexual dimorphism in the jaw length of G. mirabilis. The evolution of the elongated jaws and associated large buccopharyngeal membrane in G. mirabilis is hypothesized to increase the surface area for gas exchange during aerial respiration and may also serve to amplify the aggressive gaping display as observed in other fishes.

Ecological differences in the facultative Caribbean cleaning goby Elacatinus prochilos do not predict learning performance in discriminatory two-choice tasks.

The ecological approach to comparative cognition emphasizes that the ecological and social environment are important predictors of cognitive performance. We used this approach to test whether differences in habitat use and social behavior in the facultative Caribbean cleaning goby Elacatinus prochilos predict differences in learning performance in two discriminatory two-choice tasks. This species has two behavioral ecotypes: one that frequently engages in cleaning interactions and inhabits corals in male-female pairs (cleaning gobies) and another that rarely engages in cleaning interactions and inhabits barrel sponges in large groups (sponge-dwellers). We predicted that cleaning gobies would outperform sponge-dwellers in a pattern-cued task, which consisted of identifying the pattern on a plate that consistently provided food, while sponge-dwellers would outperform cleaning gobies in a spatial task, which consisted of identifying the location of the plate. Contrary to our predictions, there was no difference in performance between the two ecotypes. Most of the gobies performed poorly in the pattern-cued task and well in the spatial task. A possible explanation for these results is that the association of a pattern with positive and negative reinforcement may not be a pre-requisite for engaging in cleaning interactions, while spatial skills might be equally required in both ecotypes. Alternatively, the two ecotypes can flexibly adjust to new feeding conditions, which would explain their similar performance in the spatial task. Further research should investigate which aspects of E. prochilos' social and ecological environment might impose challenges that require spatial cognition and whether individuals can flexibly adjust to new habitats and feeding conditions.

Study of Loma acerinae (Microsporidia) detected from three Ponto-Caspian gobies (Gobiidae) in Ukraine.

A previously recognized Glugea-belonging Microsporidia (G. melanostomi, G. markievichi, G. naidenovi) were found in the intestinal mucosa of Neogobius melanostomus, N. fluviatilis, and Proterorhinchus semilunaris (Teleostei, Gobiidae) from lower Dnieper River and Black Sea coastal inlets, Ukraine. Light microscope observations demonstrated small spherical xenomes about 0.35 mm in diameter filled by developmental stages of parasites. Mature spores were ellipsoidal, slightly narrowed at anterior pole, sometimes ovoid or elongate in shape approximately 3.1-4.5 × 2.0-2.9 µm in size. The stained spores were elongate ovoid that are measured about 2.3-4.3 × 1.6-3.4 µm. Ultrastructural study showed that xenoma wall consisted of finely granular layer up to 350 nm wide. Numerous host-derived collagenous fibers adhered to the xenoma wall were noticed. Microtubular inclusions about 40 nm in diameter occupied the episporontal space. Mature spores displayed the polar filament arranged in one row. One to two last turns of polar filament were sharply tapered to half of diameter. The number of polar filament turns varied depending of host infected from 10 (9 + 1) in N. melanostomus to 13 (11 + 2) in N. fluviatilis and 14 (13 + 1) in P. semilunaris. The endospore thickness varied depending of host infected from 30-35 nm in case of N. fluviatiis to 40-50 nm in P. semilunaris and 60-80 nm in N. melanostomus. SSU 16S rRNA sequence analysis, blast searches, and ultrastuctural data revealed similarity of all studied microsporidians with Loma acerinae (Jirovec, 1930).

Reproductive morphology and its application in testing molecular systematic hypotheses in the family Gobiidae (Teleostei, Gobiiformes).

This study uses histological techniques to make a detailed comparison of the reproductive morphologies of four gobiid genera, Amblyeleotris, Ctenogobiops, Fusigobius and Kraemeria. Three distinct reproductive morphological patterns were observed. All species examined in the genus Fusigobius exhibit either an ovariform or testiform gonad and precursive accessory gonadal structures (pAGS) associated with each of the gonadal lobes, regardless of gonadal state. In contrast, among species of Amblyeleotris, Ctenogobiops and Kraemeria examined, pAGS were not found. Furthermore, Amblyeleotris and Ctenogobiops differ from both Kraemeria and Fusigobius in lacking AGS associated with the testiform gonad. These findings, based solely on reproductive morphology, suggest that Kraemeria and Fusigobius may be more closely related to each other than either is to Amblyeleotris and Ctenogobiops. Findings of this study support the view that reproductive morphological patterns could prove informative in elucidating evolutionary relationships within the family Gobiidae.

What can morphology tell us about ecology of four invasive goby species?

This study presents a detailed comparative analysis of external morphology of four of the most invasive goby species in Europe (round goby Neogobius melanostomus, bighead goby Ponticola kessleri, monkey goby Neogobius fluviatilis and racer goby Ponticola gymnotrachelus) and interprets some ecological requirements of these species based on their morphological attributes. The results are evaluated within an ontogenetic context, and the morphological differences between the species are discussed in terms of the question: can special external shape adaptations help to assess the invasive potential of each species? The morphometric analyses demonstrate important differences between the four invasive gobies. Neogobius melanostomus appears to have the least specialized external morphology that may favour its invasive success: little specialization to habitat or diet means reduced restraints on overall ecological requirements. The other three species were found to possess some morphological specializations (P. kessleri to large prey, N. fluviatilis to sandy habitats and P. gymnotrachelus to macrophytes), but none of these gobies have managed to colonize such large areas or to reach such overall abundances as N. melanostomus.

Gyrodactylus proterorhini in its non-native range: distribution and ability to host-switch in freshwaters.

Successful co-introduction of a parasite and its host relies not only on presence of the parasite on host individuals in the founder population but also on the ability of both host and parasite to persist in the new area. Gyrodactylus proterorhini (Monogenea) has been successfully co-introduced with its Ponto-Caspian goby hosts (Babka gymnotrachelus, Neogobius fluviatilis, Neogobius melanostomus, Ponticola kessleri, Proterorhinus semilunaris) to many freshwater systems in Europe and is now widely distributed over four large European river basins (Danube, Rhine, Scheldt and Vistula). Within Europe, higher infection levels are documented in sites further from the native host range. In North America, however, G. proterorhini appears to be absent. Host specificity of G. proterorhini tested under natural conditions showed accidental host-switching onto local fish species (native Perca fluviatilis and non-native Perccottus glenii) in the river Vistula. Further examination of host-switching under experimental conditions, however, showed that G. proterorhini were unable to survive on non-gobiid hosts longer than 24 h. Our results indicate extremely low potential for host-switching of introduced G. proterorhini to non-gobiid hosts, at least in the freshwater systems of Central and Western Europe.

Microgobius meeki as a potential bio-indicator of habitat disturbance in shallow estuarine areas: a useful tool for the assessment of estuarine quality.

The relationships between changes in habitat quality (disturbed and undisturbed sites) and the population parameters (density, size distribution, reproductive activity and diet) of a goby Microgobius meeki were investigated in a tropical estuary to assess its value as an indicator of anthropogenic changes, predominantly the effects of sedimentation and mangrove removal in shallow estuarine areas. Fish sampling surveys were conducted bimonthly between June 2009 and May 2010 over the entire estuarine gradient of the Paraguaçu River estuary, located on the central Brazilian coast. A predictive model was developed to assess the population changes of this species in 10 other tropical estuaries with different dimensions, basin features and distinct levels of anthropogenic disturbance. General linear models were used to relate the population structure of M. meeki to sediment type, habitat type resulting from mangrove conservation status, anthropogenic pressure and environmental characteristics such as salinity, dissolved oxygen concentrations and temperature. Sediment type and the presence of mangrove forests were the most effective predictors of local variability in the population structure of M. meeki. Individuals with mature gonads and high rates of feeding activity were associated predominantly with undisturbed habitats. Estuaries and estuarine sectors with high levels of sedimentation in shallow marginal areas, anthropogenic pressure from domestic and industrial effluents, and evidence of mangrove deforestation yielded the lowest capture rates of both juvenile and adult M. meeki. Based on these findings, M. meeki is identified as a potential indicator of the consequences of anthropogenic disturbance in transitional waters. A simple, but efficient collection protocol, in which overt signs of distress can be promptly observed is proposed. Testing the generality of this approach across different systems might prove useful in a broader conservation biology context.

A new species of Gobius (Perciformes: Gobiidae) from the Mediterranean Sea and the redescription of Gobius bucchichi.

A new species of the gobiid genus Gobius (Gobiidae, Perciformes), Gobius incognitus sp. nov. is described from the Mediterranean Sea, and its most morphologically similar species Gobius bucchichi is redescribed. The new species is distinguished from its congeners by: scales in lateral series 51-59; predorsal scales 25-35; opercle scaled in adults with 10-16 scales present; pectoral fin with ray count 18-20 and free tips on upper rays well developed and on the first ray longer than two thirds of the entire ray length; pelvic disc complete and with well-developed anterior membrane without lateral lobes; anterior oculoscapular canal with pore α at rear of orbit; oculoscapular row x(1) not extending forwards to pore ß; suborbital row d discontinuous with large gap below suborbital rows 3 and 4; eye diameter 1·08-1·32 in snout length; by pigment rows on cheek and pigmentation on pectoral-fin base.

Microhabitat use affects goby (Gobiidae) cue choice in spatial learning task.

This study investigated whether spatial learning ability and cue use of gobies (Gobiidae) from two contrasting habitats differed in a spatial task. Gobies were collected from the spatially complex rock pools and dynamic, homogenous sandy shores. Fishes were trained to locate a shelter under the simulated threat of predation and it was determined whether they used local or extra-maze (global) and geometric cues to do so. It was hypothesized that fishes from rock pools would outperform fishes from sandy shores in their ability to relocate shelter and the two groups would differ in their cue use. It was found that rock-pool species learnt the location of the correct shelter much faster, made fewer errors and used a combination of all available cues to locate the shelter, while sand species relied significantly more on extra-maze and geometric cues for orientation. The results reported here support the hypothesis that fishes living in complex habitats have enhanced capacity for spatial learning and are more likely to rely on local landmarks as directional cues than fishes living in mundane habitats where local cues such as visual landmarks are unreliable.

Convergent evolution of ecomorphological adaptations in geographically isolated Bay gobies (Teleostei: Gobionellidae) of the temperate North Pacific.

North Pacific Bay gobies (Teleostei: Gobioidei: Gobionellidae) inhabit bays, beaches, coastal lagoons, and estuaries of temperate Asia and North America, but are absent from the boreal northernmost Pacific. Previously, morphological characters conventionally subdivided the clade into two groups - an elongate-bodied, infaunal-inhabiting "Astrabe" group, and a deeper-bodied, non-infaunal "Chasmichthys" group - each with a disjunct East-West (amphi-) Pacific distribution. Here we use mitochondrial and multi-locus nuclear DNA sequence data to show that several morphological characters previously used to delimit these two groups have in fact arisen independently on both sides of the Pacific, revealing convergence of ecologically adaptive characters within a geographically divided clade. Basal divergence of the resultant tree coincides with a dramatic global cooling event at the Eocene/Oligocene transition, without evidence of subsequent trans-Pacific migration. A novel approach to partitioning sequence data by relative rate, as opposed to traditional gene/codon position partitioning, was used to help distinguish phylogenetic signal from noise on a per-site basis. Resulting improvements in topology and nodal support, along with decreased computational effort, suggest that this partitioning strategy may be useful for future studies in phylogenetics and phylogenomics.

Occurrence of Gobiidae larvae in a tropical Brazilian estuary, with particular emphasis on the use of size classes to categorize species guilds.

The structure and seasonal dynamics of larvae of the Gobiidae family in the Mucuri Estuary (Bahia, Brazil) were studied for nine consecutive years. Sampling was conducted at three stations in the lower estuary channel, between 2002 and 2010, in relation to season, day and night and tidal variations. A total of 5802 Gobiidae larvae, representing 15 taxa (12 species and three morphotypes), were collected in the Mucuri Estuary during this time. The highest mean ± s.d. density of fish larvae, 54·7 ± 79·8 larvae 100 m(-3), was recorded during the flood tide and night sampling. Ctenogobius boleosoma was the most abundant species (68%), being dominant in the rainy and dry seasons and had a long reproductive period. This species was classed as a marine estuarine-opportunist because it was observed at high frequencies and active larvae entering the estuary between 6·1 and 12·0 mm standard length (L(S)). Gobionellus oceanicus, second in abundance (12%), occurred only in later larval stages but did not use the estuary as a preferred location for spawning, being classed a marine estuarine dependent. Microgobius carri (11%) was represented in all L(S) classes and was resident in the estuary for spawning, remaining there throughout their life cycle. The other species were considered rare due to their low densities and could not be classified in any guild.

Molecular phylogenetics of Gobioidei and phylogenetic placement of European gobies.

Gobioidei is one of the largest suborders of teleost fishes, with nearly 2000 extant species currently recognized. They have a worldwide distribution and show a spectacular variety in morphology, ecology, and behavior. Despite their importance, phylogenetic relationships among many groups of gobioids (including some of the major lineages) still remain poorly understood. In this study, we analyze sequence data of five molecular markers (two mitochondrial and three nuclear) averaging 6000 bp for 222 species of gobioids. Our study is the first to include both multiple nuclear and mitochondrial genes to reconstruct a comprehensive multilocus phylogeny of gobioids encompassing most major lineages representing the overall diversity of one of the most speciose vertebrate lineages. Two separate datasets are produced and used to specifically address the phylogenetic placement of Rhyacichthyidae and Odontobutidae, and the phylogenetic relationships among gobioid lineages. Our results strongly support that the initial split in the gobioid tree separated a clade containing Rhyacichthyidae+Odontobutidae as the sister group of all other lineages. The family Eleotrididae branches off the gobioid tree after the Rhyacichthyidae+Odontobutidae clade, followed by the Butidae as sister group to the Gobiidae. Additionally, several major monophyletic groups are confidently identified within the two major Gobiidae subclades, the gobiine-like gobiids and the gobionelline-like gobiids. Robustness of the phylogenetic trees inferred here is significantly higher than that of previous studies, hence our results provide the most compelling molecular phylogenetic hypothesis of Gobioidei thus far. For the first time, we provide a comprehensive sampling of European gobies that traditionally have been divided into "transverse" gobies and "sand gobies". We show that the European gobies cluster in three distinct lineages, the Pomatoschistus-, Aphia-, and Gobius-lineages. The former resolved within the gobionelline-like gobiids and the latter two within the gobiine-like gobiids. These findings have significant implications for our understanding of the phylogeographic origin of European gobies in the light of the closure of the Paratethys. A rogue taxon analysis identified Kraemeria as an unstable taxon decreasing support at the base of the gobiine-like gobiids. Removal of this rogue taxon significantly increased phylogenetic resolution in that part of the tree and revealed additional insights into early bursts of cladogenesis of the gobiine-like gobiids.

Two new species of Varicus from Caribbean deep reefs, with comments on the related genus Pinnichthys (Teleostei, Gobiidae, Gobiosomatini, Nes subgroup).

Tropical deep reefs (~40-300 m) are diverse ecosystems that serve as habitats for diverse communities of reef-associated fishes. Deep-reef fish communities are taxonomically and ecologically distinct from those on shallow reefs, but like those on shallow reefs, they are home to a species-rich assemblage of small, cryptobenthic reef fishes, including many species from the family Gobiidae (gobies). Here we describe two new species of deep-reef gobies, Varicusprometheussp. nov. and V.roatanensissp. nov., that were collected using the submersible Idabel from rariphotic reefs off the island of Roatan (Honduras) in the Caribbean. The new species are the 11th and 12th species of the genus Varicus, and their placement in the genus is supported by morphological data and molecular phylogenetic analyses. Additionally, we also collected new specimens of the closely-related genus and species Pinnichthysaimoriensis during submersible collections off the islands of Bonaire and St. Eustatius (Netherland Antilles) and included them in this study to expand the current description of that species and document its range extension from Brazil into the Caribbean. Collectively, the two new species of Varicus and new records of P.aimoriensis add to our growing knowledge of cryptobenthic fish diversity on deep reefs of the Caribbean.

Ponticolaalasanicus sp. n. (Gobiiformes, Gobiidae) from the Alazani River Basin, Georgia.

Background: The South Caucasus Region and Georgia, in particular, is a biodiversity hotspot and characterised by high diversity of landscapes and ecosystems, as well as high levels of endemism. At the same time, diversity of freshwater organisms in the region remains poorly studied, including fishes. The freshwater fish fauna of the South Caucasus Region consists of 119 fish species, of which 13 species belong to the order Gobiiformes. It should be noted that gobies are amongst the poorly studied taxa in Georgia and probably unknown/undescribed species still living in the Georgian freshwater ecosystems which requires further research. New information: Ponticolaalasanicus, a new species is described from the Alazani River, western Caspian Sea Basin, Georgia. It is distinguished from its congeners in the Caspian and Black Sea Basins by having the following features: dorsal fin with VI-VII spines and 15½-16½ branched rays, anal fin with 10½-12½ branched rays; lateral line with 48-55 scales; laterally compressed body with dark brown and black blotches - scales ctenoid; first and second dorsal fins almost touching with dorsal fins bases; head large, depressed, wider than deep, its length approaches almost 3.4th of standard length; nape scaled completely; cycloid scales cover upper part of opercle, cheeks noticeably swollen; snout longer than eye, eye diameter 4.5 times its head length; lower jaw slightly protruding; upper lip is uniform; pelvic disc short, elongated and flat, not reaching the anus; the pectoral fins extends vertically through first branched dorsal fin; caudal fin rounded. Ponticolaalasanicus sp. n. belongs to P.syrman group and it is separated by a minimum Kimura 2-parameter distance of 3.5, 3.6 and 4.8% from P.syrman, P.iranicus and P.patimari, respectively.

Delayed recovery and host specialization may spell disaster for coral-fish mutualism.

Mutualisms are prevalent in many ecosystems, yet little is known about how symbioses are affected by ecological pressures. Here, we show delayed recovery for 13 coral-dwelling goby fishes (genus Gobiodon) compared with their host Acropora corals following four consecutive cyclones and heatwaves. While corals became twice as abundant in 3 years postdisturbances, gobies were only half as abundant relative to predisturbances and half of the goby species disappeared. Although gobies primarily occupied one coral species in greater abundance predisturbances, surviving goby species shifted hosts to newly abundant coral species when their previously occupied hosts became rare postdisturbances. As host specialization is key for goby fitness, shifting hosts may have negative fitness consequences for gobies and corals alike and affect their survival in response to environmental changes. Our study is an early sign that mutualistic partners may not recover similarly from multiple disturbances, and that goby host plasticity, while potentially detrimental, may be the only possibility for early recovery.

Comparative Analysis of Complete Mitogenomes of Two Oxyurichthys Gobies and Their Phylogenetic Implication.

Oxyurichthys is a genus of goby that is widespread in the tropical Indo-West Pacific region. Oxyurichthys species are usually found in estuarine and coastal marine habitats. In Southeast Asia, they are commercial fishes and often collected by trawling to serve the market's demand. The mitogenome serves as a good marker for investigating the systematics and evolution of fishes, but the mitogenome of Oxyurichthys species remains unknown. In this study, mitogenomes of two Oxyurichthys gobies, O. ophthalmonema and O. microlepis, were characterized and compared. The sizes of the mitogenomes were 16,504 bp and 16,506 bp for O. ophthalmonema and O. microlepis, respectively. Mitogenomes of these two species were similar in gene content and structure. Both included 37 genes and a control region. The two Oxyurichthys mitogenomes shared similar gene features and base composition with other recorded gobies. Typical conserved blocks (CSB-1, CSB-2, CSB-3 and CSB-D) were found in the control region of both species. Phylogenetic analyses based on concatenation of 13 protein-coding genes and 2 rRNAs revealed that the two Oxyurichthys species clustered together and were sister to species of the genera Sicydium, Sicyopterus and Stiphodon. The findings of the present study support previous evolutionary studies of gobies using other molecular markers.

Morphological comparison of the cranial movement apparatus in mudskippers (Gobiidae: Oxudercinae).

Possession of the neck allows vertebrates to move the head independently from the trunk. Fish do not have the neck and thus the cranial mobility could be limited. Oxudercine gobies show full range of habitat transition from aquatic to terrestrial environments and exhibit flexible cranial movement, yet the cranium-movement apparatus is little known. In this study, we investigated the anatomy of the structure of the eight oxudercine gobies, Oxuderces nexipinnis, Parapocryptes serperaster, Pseudapocryptes elongatus, Scartelaos histophorus, Boleophthalmus boddarti, Periophthalmus chrysospilos, Periophthalmodon schlosseri, and Periophthalmodon septemradiatus. These species share similarities in the specialized features of the craniovertebral joint and the epaxials attaching onto different locations of the neurocranium. On the other hand, large space between the ventral portions of the craniovertebral joint only occurs in O. nexipinnis, Pd. elongatus, Pn. schlosseri and Pn. septemradiatus. Hypaxials are hypertrophied at the insertion point and attach more anteriorly onto the ventral side of the neurocranium in B. boddarti, O. nexipinnis, Pa. serperaster, Pd. elongatus, and S. histophorus, whereas the muscles are small and attach posteriorly in the remaining species. There were significant differences in the area occupancy ratio of the post-cranial neural spines, the lever arm ratio of the cranial rotation, and the angle between the horizontal plane and the plane through the craniovertebral joint among the species. The cranial depression presumably facilitates grazing of oxudercine gobies in their early stage of terrestrial transition, whereas the cranial elevation parameters are contradictory to the terrestrial gradient. The cranium-movement morphometrics partially agree with the phylogeny.

Characterization of the complete mitochondrial genome of the Northern Mud Gudgeon, Ophiocara porocephala (Perciformes: Eleotridae) with phylogenetic implications.

The first mitochondrial genome of Ophiocara porocephala was determined by the combination of next-generation sequencing (NGS) and Sanger sequencing methods. A complete circular mitogenome of O. porocephala (16,529 bp) consisted of 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and two non-coding regions, including a control region (D-loop) and a light strand origin of replication (OL). Two start codons (ATG and GTG) and four stop codons (TAG, TAA, TA-, and T-) were used in all the PCGs. Except for ND6 and eight transfer RNAs (tRNAs), all the other genes were encoded in the heavy strand. Based on phylogenetic analysis, O. porocephala formed a clade with three other species in the subfamily Butinae, while the other 10 made a subfamily Eleotrinae clade.

A new species of Trimma (Pisces: Gobiidae) from western Thailand, north-eastern Indian Ocean.

A new species of Trimma is described from the islands just off the Thailand coast near Phuket. Trimma ukkriti n.sp. lacks scales on the cheek and opercle, but has ctenoid scales in the midline of the nape, has an elongate second spine of the first dorsal fin which reaches posteriorly to between the base of the spine and the base of the 4th ray of the second dorsal fin when adpressed, 19-20 pectoral-fin rays with 6-13 branched rays in the middle of the fin, an unbranched 5th pelvic-fin ray, which is 48-67% the length of the 4th ray, a U-shaped interorbital trench with no fleshy median ridge, a poorly developed postorbital trench ending at the 5th papilla in row p (which has 6 papillae in total), and row c beneath the eye consists of 6 papillae. When live and freshly collected, the species is very similar in appearance to T. okinawae and T. readerae, with orange to red spots on the head and body.