The Leiognathus splendens complex (Perciformes: Leiognathidae) with the description of a new species, Leiognathus kupanensis Kimura and Peristiwady

Taxonomic analysis of a group of morphologically similar ponyfishes (Perciformes: Leiognathidae) establishes the Leiognathus splendens complex comprising four valid species: L. jonesi James, 1971, widely distributed in the Indo-West Pacific, from Mauritius to Papua New Guinea, north to Hainan I. (China), and south to Brisbane, Australia; L. kupanensis sp. nov., currently known only from Kupang, Timor, Indonesia; L. rapsoni Munro, 1964, currently known only from India, Indonesia, and Papua New Guinea, and L. splendens Cuvier, 1829, widely distributed in the eastern Indian and western Pacific oceans, from India to Papua New Guinea, and from southern Japan to northern Australia. The L. splendens complex can be defined by the following combination of characters: body depth 42–60% of standard length; mouth protruding downward; slender, minute teeth uniserially on jaws; lower margin of orbit above the horizontal through the gape when mouth closed; breast almost completely scaled; lateral line complete, and a dark blotch on top of spinous dorsal fin. Diagnostic characters of the members are as follows: L. jonesi —anterior dorsolateral body surface with a semicircular naked area on nape, and a paler dark blotch on spinous dorsal fin; L. kupanensis —anterior dorsolateral body surface widely naked; L. rapsoni —cheek scaled; L. splendens —anterior dorsolateral body surface completely scaled and a jet black blotch on spinous dorsal fin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41595/1/10228_2005_Article_283.pd

Search for gravitational waves associated with gamma-ray bursts detected by Fermi and Swift during the LIGO–Virgo run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC–2020 March 27 17:00 UTC). We conduct two independent searches: a generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate

Differentiation in morphology and electrical signalling in four species of para- and sympatric Marcusenius (Teleostei: Mormyridae) from Côte d’Ivoire, West Africa

Marcusenius Gill, 1862 species were sampled from the Bandama River and the Comoé River in Côte d’Ivoire, West Africa. Marcusenius gracilis sp. nov. was differentiated from M. senegalensis (Steindachner, 1870), Marcusenius ussheri (Günther, 1867) and M. furcidens (Pellegrin, 1920) in electric organ discharges (EOD), and morphologically from all other West African congeners. Principal component analysis showed significant morphological differentiation among the four Ivorian species. Principal component 1 was loaded most strongly by characters affecting swimming power and manoeuvrability. The morphologically most similar pair, M. furcidens and M. gracilis sp. nov., are distinguished by their EOD waveforms and a sexual dimorphism in the anal fin base in the latter not present in the former. M. ussheri is distinguished by a sexual dimorphism in its EOD waveform not observed in the other three species. This system is an opportunity to study how far the fine-tuning of character displacement among syntopic species can go

Morphological and electrophysiological field observations on electric freshwater fish of the genus Mormyrops Müller 1843 (Teleostei: Mormyridae) from West and southern Africa

Different specimens of Mormyrops anguilloides (Linnaeus 1758) were reported to display electric organ discharge (EOD) pulses of either initially head-positive or initially negative polarity, a hypothetical sex difference that has not been substantiated to date. The morphology and EODs of M. anguilloides of both sexes and a sexually mature size from the Comoé and Bandama rivers, Côte d'Ivoire, and the Lower and Middle Zambezi, Mozambique, displayed initially positive EODs. The morphologically similar M. breviceps Steindachner 1895 of both sexes and a sexually mature size from the Bandama River displayed initially head-negative EODs of biphasic waveform and long duration (0.93–1.15 ms) in the very-low-frequency spectral range. Mormyrops anguilloides from the Comoé and Bandama rivers were differentiated in caudal peduncle depth and in EOD waveform, pulse duration and spectral energy content. The former samples displayed a biphasic, lower-frequency EOD pulse of up to 0.42 ms duration, the latter a tetraphasic, high-frequency EOD of up to 0.33 ms. It is suggested that reports of EODs of both polarities in M. anguilloides indicate the presence of an unrecognised species