A revision of the gobiid fish genus Pseudogobius (Teleostei, Gobiidae, Tridentigerinae), with description of seven new species from Australia and South-east Asia

The tridentigerine genus Pseudogobius is widespread, from temperate to tropical areas of the Indo-west Pacific. A morphological review of the genus was carried out, with the initial focus on South-east Asian and Australian species. There are about 21 nominal species in the genus; however, the type specimens for some nominal species are missing. Our work recognises 15 valid species so far, including seven new species, which are described herein: P. aquilonius n. sp., P. cinctus n. sp., P. eos n. sp., P. hoesei n. sp., P. jeffi n. sp., P. rhizophora n. sp. and P. verticalis n. sp. We also conclude that P. poicilosoma (Bleeker, 1849) is the senior synonym of P. javanicus (Bleeker, 1856). Pseudogobius poicilosoma, P. gastrospilos (Bleeker, 1853) and P. javanicus are accepted here as conspecific, although the types are in poor condition (note that all three names were given to specimens collected within close proximity to each other in coastal Java, Indonesia). A key to valid species is presented. The revision benefited from an adaptive feedback loop with companion genetic analyses, with the most comprehensive data available for the Australian region. Broader preliminary genetic data suggest the potential for recognition of additional cryptic species, with the current study providing a platform for future systematic work. Pseudogobius are a prominent part of estuarine biodiversity in the Indo-west Pacific, and this study helps to highlight the need to better understand the taxonomy and conservation requirements of cryptobenthic fishes.

Niche-restriction and regional endemism driving facultative coevolutionary symbiosis --- Ecology and phylogeography of two new snapping shrimps associated with a gobiid fish

Using ecological, taxonomic and phylogenetic approaches, we here describe geographically isolated symbiotic relationships between a gobiid fish and two misdescribed alpheid snapping shrimps. This was discovered in the southwestern province of the Persian Gulf, more specifically, in the harsh hyperarid intertidal zone separating the coastal ecosystem from the Middle East desert. Phylogenetic results based on the 16S rRNA gene indicate the existence of two new cryptic species within the Alpheus lobidens De Haan, 1849 species complex, described and named here as Alpheus qatari n. sp. and Alpheus arabicus n. sp. Furthermore, phylogeographic results suggest resurrection of Alpheus crassimanus Heller, 1865 within the same species complex. A phylogenetic comparison of the endemic Arabic goby Cryptocentroides arabicus (Gmelin, 1789) with some of its congeners confirms its presence along both sides of the Persian Gulf. Ecologically noteworthy is the facultative symbiotic interaction between this endemic Arabic goby with the two mentioned endemic alpheid shrimps within two distinct ecosystems. Therefore, we herewith report a case of exceptional symbiosis of a littoral fish species with two potential partners, niche-restricted to shallow intertidal zones, however, with niche differentiation defined by the adaptability of each associated shrimp species. Furthermore, the presence of the goby depends on suitable sediment needed for burrowing: either gravel in the periphery of coral reefs, or mud in the periphery of mangrove ecosystems. The corresponding ecology, taxonomic status and phylogeography are discussed with respect to the recorded facultative character of the symbiotic relationship.

Otolith measurements to estimate standard length of gobiid fish (Teleostei: Gobiiformes) from the Persian Gulf and Oman Sea

The relationship between morphometric characters (length, weight and height) of otolith and fish standard length was determined for six intertidal gobiid species from the northern Persian Gulf and Oman Sea. A total of 144 sagittal otoliths were extracted and anlysed from Periophthalmus waltoni, Boleophthalmus dussumieri, Scartelaos tenuis, Istigobius ornatus, Bathygobius meggitti and Trypauchen vagina. Regression equations were derived and found that there is no significant difference in regression coefficients between left and right otoliths of the species studied. Results of the study showed that otolith length (OL) and height (OH) could estimate standard length in all the species studied except in T. vagina, where the otolith weight gave the best estimate of standard length. Results clearly indicated that otolith dimensions of the gobiid fishes studied could provide information about the species and size.

Assessing trophic relationships between shallow-water black corals (Antipatharia) and their symbionts using stable isotopes

Shallow-water antipatharians host many symbiotic species, which spend their adult life with their host and/or use them to have access to food. Here we determine the trophic relationships between four common macrosymbionts observed on/in Cirripathes anguina, Cirrhipathes densiflora and Stichopathes maldivensis in SW Madagascar. These include the myzostomid Eenymeenymyzostoma nigrocorallium, the gobiid fish Bryaninops yongei, and two palaemonid shrimps, Pontonides unciger and Periclimenes sp. The first is an endosymbiont living in the digestive tract, while the others are ectosymbionts. The analyses show that most likely (i) none of the symbionts uses the host as a main food source, (ii) nocturnal plankton represents a main part of the diet of antipatharians while the symbionts feed preferentially on diurnal plankton, (iii) the myzostomid has the narrowest trophic niche, (iv) the two shrimps have distinct trophic niches and feed at lower trophic level than do the other symbionts. Concerning the myzostomids, they had the same δ13C values but had significantly higher δ15N values than the hosts. TEFs (Trophic Enrichment Factors) recorded were Δ13C = 0.28 ± 0.25 ‰ and Δ15N = 0.51 ± 0.37 ‰, but these were not high enough to explain a predator-prey relationship. These worms rely on the coral diet but may also ingest host fluids explaining the slight enrichment in heavier nitrogen isotopes. On the other hand, the ectosymbionts use the coral as a pathway to have access to food from the midwater: they feed from the water passing nearby the black corals, but a kleptoparasitic behaviour cannot be excluded.

A new species of Schindler's fish (Teleostei: Gobiidae: Schindleria) from the Malay Archipelago (Southeast Asia), with notes on the caudal fin complex of Schindleria

Schindleria macrodentata sp. nov., a new species of the paedomorphic gobiid fish genus Schindleria, is described from the Malay Archipelago. The two specimens were collected in 1929 during the “Dana Expedition” in the Molucca Sea between Sulawesi and Halmahera islands (00°29′N, 125°54′E) (Indonesia) and in the Sulu Sea close to Panay Island (11°43’N, 121°43′E) (Philippines). The new species is characterized by a slender body (body depth at pectoral fin base 3.6–3.7 % of SL and at anal fin origin 3.9–4.8 % of SL), a long second dorsal fin (first dorsal fin absent) originating distinctly anterior to the origin of the anal fin (predorsal length 61.8–65.2 % of SL and preanal length 71.7–75.8 % of SL), a short tail (from anus to tip of longest caudal fin ray) (22.1 % of SL), 19–20 dorsal fin rays and 10 anal fin rays, first anal fin ray below 9th dorsal fin ray, few large, widely spaced teeth in the upper and the lower jaws (7 on the premaxilla and 6 on the dentary), an elongated pectoral radial plate (length 3.7–4.5 % of SL) and, in the caudal skeleton, a procurrent ray with an additional spiny process at its base. No distinct urogenital papilla and no pigmentation on body are developed. In this study we present three morphological traits until now not considered as diagnostic characters for Schindleria, the shape of the pectoral radial plate, the shape of the last procurrent caudal spine and the shape of the arch formed by the lower jaw. We also discuss the caudal-fin skeleton of Schindleria, a character developing beyond the larval stages. The record of S. macrodentata is the first of the genus Schindleria for Indonesia and, at more than 100 km distant to the next shore, it is the first offshore record of a Schindler's fish.