Hyporthodus griseofasciatus (Perciformes: Epinephelidae), a new species of deep-water grouper from the west coast of Australia.

A new species of deep-water epinephelid fish is described from the west coast of Australia based on 14 specimens, 99-595 mm standard length. Hyporthodus griseofasciatus sp. nov. is endemic to Western Australia from Barrow Island to Two Peoples Bay in depths of 76-470 m. It has a series of eight grey bands alternating with eight brown bands along the body and the soft dorsal, soft anal and caudal fin margins are pale cream to white. It is distinguished from its nearest congener, H. ergastularius, by the presence of a star-like pattern of radiating lines on the head versus an overall brownish colour in the latter as well as significant differences in the quantitative analyses of 25 morphological characters. The two species have allopatric distributions on either side of the Australian continent. H. griseofasciatus is distinguished from H. octofasciatus by several grey bands being distinctly narrower than other grey bands (vs. all grey bands subequal in the latter) and the presence of broad white margins on the dorsal, caudal and anal fins (vs. narrow or absent in the latter). Some scale counts appear to also differ. Analyses of mitochondrial cytochrome oxidase subunit 1 sequences revealed reciprocally monophyletic clades with fixed differences and genetic distances typical of recently diverged species of fishes.

Climate-assisted persistence of tropical fish vagrants in temperate marine ecosystems.

Rising temperatures and extreme climate events are propelling tropical species into temperate marine ecosystems, but not all species can persist. Here, we used the heatwave-driven expatriation of tropical Black Rabbitfish (Siganus fuscescens) to the temperate environments of Western Australia to assess the ecological and evolutionary mechanisms that may entail their persistence. Population genomic assays for this rabbitfish indicated little genetic differentiation between tropical residents and vagrants to temperate environments due to high migration rates, which were likely enhanced by the marine heatwave. DNA metabarcoding revealed a diverse diet for this species based on phytoplankton and algae, as well as an ability to feed on regional resources, including kelp. Irrespective of future climate scenarios, these macroalgae-consuming vagrants may self-recruit in temperate environments and further expand their geographic range by the year 2100. This expansion may compromise the health of the kelp forests that form Australia's Great Southern Reef. Overall, our study demonstrates that projected favourable climate conditions, continued large-scale genetic connectivity between populations, and diet versatility are key for tropical range-shifting fish to establish in temperate ecosystems.

Review of Australian species of Plectranthias Bleeker and Selenanthias Tanaka (Teleostei: Serranidae: Anthiadinae), with descriptions of four new species.

Australian species of the anthiadine genera Plectranthias and Selenanthias are reviewed. Twenty-two species of Plectranthias and two species of Selenanthias are recorded from Australian waters: Plectranthias sp. 1 from a seamount north of Middleton Reef and Norfolk Ridge, Tasman Sea; P. alleni Randall from off southwest Western Australia; P. azumanus (Jordan Richardson) from off southwest Western Australia; P. bennetti Allen Walsh from Holmes Reef, Coral Sea; P. cruentus Gill Roberts from Lord Howe Island, and possibly off Stradbroke Island, Queensland; P. ferrugineus n. sp. from the North West Shelf and Arafura Sea; P. fourmanoiri Randall from Christmas Island and Holmes Reef, Coral Sea; P. grahami n. sp. from off central New South Wales, Tasman Sea; P. inermis Randall from Christmas Island; P. japonicus (Steindachner) from the Arafura Sea and North West Shelf; P. kamii Randall from the Coral Sea, Lord Howe Island and Christmas Island; P. lasti Randall Hoese from the North West Shelf and off Marion Reef, Queensland; P. longimanus (Weber) from the Timor Sea, Great Barrier Reef, Coral Sea and southern Queensland; P. maculicauda (Regan) from southeastern Australia; P. mcgroutheri n. sp. from the North West Shelf; P. megalophthalmus Fourmanoir Randall from northeast of the Whitsunday Islands, Queensland; P. melanesius Randall from southeastern Queensland and a seamount north of Middleton Reef; P. moretonensis n. sp. from off Stradbroke Island, Queensland; P. nanus Randall from the Cocos (Keeling) Islands, Christmas Island, Great Barrier Reef and Coral Sea; P. retrofasciatus Fourmanoir Randall from the Great Barrier Reef; P. robertsi Randall Hoese from off Queensland, Coral Sea; P. winniensis (Tyler) from the Great Barrier Reef and Coral Sea; Selenanthias analis Tanaka from the North West Shelf and Arafura Sea; and S. barroi (Fourmanoir) from west of Lihou Reef, Coral Sea. Five of the species represent new records for Australia: P. azumanus, P. kamii, P. megalophthalmus, P. melanesius and S. barroi. Previous records of P. megalophthalmus from the North West Shelf are based on misidentified specimens of P. lasti. Records of P. wheeleri from the North West Shelf are based on specimens here identified as P. mcgroutheri n. sp. A record of P. yamakawai Yoshino from Christmas Island is based on a misidentified specimen of P. kamii. Plectranthias retrofasciatus was previously recorded from the Great Barrier Reef as P. pallidus Randall Hoese, here shown to be a junior synonym of P. retrofasciatus. Video-based records of P. kelloggi from the Great Barrier Reef appear to be based on P. retrofasciatus. Identification keys, diagnoses, character summaries, photographs and Australian distribution information are presented for all species. Full descriptions are provided for the new species and for those newly recorded from Australia.

A new genus and two new species of miniature clingfishes from temperate southern Australia (Teleostei, Gobiesocidae).

A new genus and two new species of miniature clingfishes are described based on specimens collected from dense stands of macroalgae in intertidal and shallow subtidal areas along the coast of southern Australia. The new genus, Barryichthys, is distinguished from other genera of the Gobiesocidae by unique features of the adhesive disc, including elongate papillae in adhesive disc regions A and B, the reduction and/or loss of several elements of the cephalic lateral line canals, the lower gill arch skeleton, and the neurocranium, and by having two distinct types of pectoral-fin rays. Barryichthyshutchinsi is described based on 19 specimens (12.4-18.7 mm SL) from Western Australia and South Australia. Barryichthysalgicola is described based on 22 specimens (9.0-21.0 mm SL) from Victoria, New South Wales and Tasmania. The new species are distinguished from each other by characters of body and head shape, vertebral counts, and aspects of live colour pattern. The new genus shares several characters in common with Parvicrepis, another genus of miniature gobiesocids from southern Australia that also inhabits macroalgae habitats. The many reductions and novel characters of Barryichthys are discussed within the context of miniaturisation.

Scolopsis meridiana, a new species of monocle bream (Perciformes: Nemipteridae) from northern Australia.

Scolopsis meridiana n. sp., described from 30 specimens collected from northern Australia, is closely related to S. taenioptera, both species having a dorsal scaled area on the head extending anteriorly to between the anterior margin of the eye and anterior nostril, the upper part of the pectoral-fin base with a reddish blotch when fresh, and lacking a small antrorse spine below the eye. However, the new species is distinguished from the latter by having two bands across the snout dorsum (vs. one band in S. taenioptera), 18-20 diagonal lines on the lateral body surface below the lateral line (diagonal lines absent), the posterior nostril horizontally elongated (vertically elongated), a deep caudal-peduncle and short pre-dorsal-fin length. Scolopsis meridiana is distributed in northern Australia, whereas S. taenioptera occurs in Southeast Asia. Two geographic populations of S. taenioptera (Philippines and remaining Southeast Asian region) are recognized following morphological and genetic analyses.

Seascape genomics reveals fine-scale patterns of dispersal for a reef fish along the ecologically divergent coast of Northwestern Australia.

Understanding the drivers of dispersal among populations is a central topic in marine ecology and fundamental for spatially explicit management of marine resources. The extensive coast of Northwestern Australia provides an emerging frontier for implementing new genomic tools to comparatively identify patterns of dispersal across diverse and extreme environmental conditions. Here, we focused on the stripey snapper (Lutjanus carponotatus), which is important to recreational, charter-based and customary fishers throughout the Indo-West Pacific. We collected 1,016 L. carponotatus samples at 51 locations in the coastal waters of Northwestern Australia ranging from the Northern Territory to Shark Bay and adopted a genotype-by-sequencing approach to test whether realized connectivity (via larval dispersal) was related to extreme gradients in coastal hydrodynamics. Hydrodynamic simulations using CONNIE and a more detailed treatment in the Kimberley Bioregion provided null models for comparison. Based on 4,402 polymorphic single nucleotide polymorphism loci shared across all individuals, we demonstrated significant genetic subdivision between the Shark Bay Bioregion in the south and all locations within the remaining, more northern bioregions. More importantly, we identified a zone of admixture spanning a distance of 180 km at the border of the Kimberley and Canning bioregions, including the Buccaneer Archipelago and adjacent waters, which collectively experiences the largest tropical tidal range and some of the fastest tidal currents in the world. Further testing of the generality of this admixture zone in other shallow water species across broader geographic ranges will be critical for our understanding of the population dynamics and genetic structure of marine taxa in our tropical oceans.

Sexually selected females in the monogamous Western Australian seahorse.

Studies of sexual selection in monogamous species have hitherto focused on sexual selection among males. Here, we provide empirical documentation that sexual selection can also act strongly on females in a natural population with a monogamous mating system. In our field-based genetic study of the monogamous Western Australian seahorse, Hippocampus subelongatus, sexual selection differentials and gradients show that females are under stronger sexual selection than males: mated females are larger than unmated ones, whereas mated and unmated males do not differ in size. In addition, the opportunity for sexual selection (variance in mating success divided by its mean squared) for females is almost three times that for males. These results, which seem to be generated by a combination of a male preference for larger females and a female-biased adult sex ratio, indicate that substantial sexual selection on females is a potentially important but under-appreciated evolutionary phenomenon in monogamous species.

Sympatric speciation as a consequence of male pregnancy in seahorses.

The phenomenon of male pregnancy in the family Syngnathidae (seahorses, pipefishes, and sea dragons) undeniably has sculpted the course of behavioral evolution in these fishes. Here we explore another potentially important but previously unrecognized consequence of male pregnancy: a predisposition for sympatric speciation. We present microsatellite data on genetic parentage that show that seahorses mate size-assortatively in nature. We then develop a quantitative genetic model based on these empirical findings to demonstrate that sympatric speciation indeed can occur under this mating regime in response to weak disruptive selection on body size. We also evaluate phylogenetic evidence bearing on sympatric speciation by asking whether tiny seahorse species are sister taxa to large sympatric relatives. Overall, our results indicate that sympatric speciation is a plausible mechanism for the diversification of seahorses, and that assortative mating (in this case as a result of male parental care) may warrant broader attention in the speciation process for some other taxonomic groups as well.