Submersible diving in the 1980/90s in the Bahamas and Cuba and 2013–2018 at Curaçao, Dominica, and Roatan resulted in the collection of a new species of Polylepion, a genus of wrasse previously known only from the Indian and Pacific Oceans. The new species, which inhabits the rariphotic reef-fish faunal zone at depths of 219–457 m, is another example of a deep-reef species belonging to a largely shallow-reef family, in this case the family Labridae. Here, we describe the new species and provide a phylogenetic placement for it by adding new sequence data from 12 genetic markers for the new species and one of its two congeners (P. cruentum from the eastern Pacific Ocean) to a previously published dataset comprising 336 species of wrasses that includes the other congener, P. russelli, from the Indian and West/Central Pacific Oceans. Our results resolve the phylogenetic history of the species of Polylepion and provide the first molecular support for the monophyly of the genus.

The new anchovy Stolephorus meteorum, formerly confused with Stolephorus indicus, is described on the basis of 19 specimens collected from the southern Red Sea. Four other species, previously confused with or placed in the synonymy of S. indicus, have been either redescribed (Stolephorus commersonnii), described as new (Stolephorus belaerius), or resurrected from its synonymy (Stolephorus balinensis and Stolephorus scitulus). The new species shares with the latter four species, plus S. indicus, a relatively short maxilla and pelvic fins, and six or fewer prepelvic scutes but differs from them in the combination of some other characters, including intermediate numbers of gill rakers (total gill rakers on first gill arch 40–43, modally 41), 41 vertebrae, a large head and narrower interorbital area, and longer pelvic fins. A genetic analysis of the mitochondrial cytochrome oxidase I gene (COI) of S. meteorum, new species, S. balinensis, S. belaerius, and S. indicus revealed each species to be genetically divergent from the others by 2.5–3.6% uncorrected distance.

The Stripetail Darter, Etheostoma kennicotti (Putnam), is widely distributed in tributaries of the lower Ohio River, the upper Green River system, the Clarks River system, throughout the Tennessee River system, the Laurel River system, and the upper Cumberland River system. Etheostoma cumberlandicum Jordan and Swain was described in 1883 from a population sampled in the Clear Fork system that drains to the upper Cumberland. A previous morphological analysis led to the placement of E. cumberlandicum into the synonymy of E. kennicotti. Results from molecular phylogenetic and relaxed molecular clock analyses, genetic variation at 25 microsatellite loci, morphological disparity in meristic traits, and variation in pigmentation from specimens sampled throughout the geographic distribution of E. kennicotti (s.l.) indicate E. cumberlandicum is a distinct species and there are multiple undescribed species masquerading as E. kennicotti. We elevate Etheostoma cumberlandicum out of synonymy and propose Moonbow Darter as the common name for the species. The results of the phylogenetic analyses are discussed in the context of the historical biogeography of rivers draining the Eastern Highlands of North America.

Triodon macropterus, the Three-tooth Puffer, is the sole extant representative of Triodontidae. It is characterized by a large pelvic fan that it flares when disturbed. Unlike Tetraodontidae (pufferfishes) and Diodontidae (porcupinefishes), T. macropterus has not previously been documented to inflate its abdomen although some nineteenth-century reports implied that it can. Those reports were rejected by a mid-twentieth-century anatomical study, and no new information about inflation in T. macropterus has been reported in the intervening 70 years, in part because the species was rarely collected. In this study, we used a combination of imaging techniques to investigate if T. macropterus can inflate. We examined 13 photographs of T. macropterus in which the pelvic fan was prominently flared; in seven of these, the abdomen was also inflated. We also studied captive T. macropterus at the Okinawa Churaumi Aquarium, which allowed us to make videographic and ultrasound studies of live individuals to confirm inflation behavior in this species. Videography shows that pelvic-fan flaring always preceded inflation. Ultrasound data from four trials of one captive individual show that water is buccal pumped for inflation into the stomach to produce an increase in volume of 30%. Powerful adduction of the suspensorium correlates with stomach inflation. We prepared x-rays and dissected three specimens to evaluate mobility of the long pelvic bone and its role in expanding the ventral abdominal recess during pelvic-fan flaring. We also studied the digestive tract and discovered a thin-walled pyloric region of the stomach that allows inflation to occur. Differences between the inflation mechanism of T. macropterus and those of tetraodontids and diodontids include: (1) inflation is slower and less extreme in T. macropterus; (2) T. macropterus has a pelvic bone that expands the ventral abdominal recess; (3) T. macropterus has smaller folds in the peritoneum and these are ventral to, rather than dorsal to, the digestive tract; (4) the ribs and long postcleithra of T. macropterus limit abdominal inflation; (5) the first branchiostegal ray of T. macropterus is much smaller than in tetraodontids and diodontids, which use the expanded bone to rapidly pump water for inflation; and (6) the pectoral girdle of T. macropterus is larger and much less mobile than that of tetraodontids and diodontids. Although we interpret that inflation serves similar roles in defense, the differences in the inflation mechanism of T. macropterus suggest that it evolved independently, and optimization of inflation behavior on three phylogenetic hypotheses for Tetraodontiformes supports this interpretation.

We here describe a new Caecilia from Parque Nacional Natural Yaigojé Apaporis, Taraira, Vaupés, Colombia, near the Brazilian border. Although this new species is only represented in collections by three specimens, it is recognizable from all other congeners by virtue of its head shape, its dentition, its counts of primary and secondary grooves, its oval dermal scales, and its small terminal shield. Although its phylogenetic relationships are unknown, it seems most similar to C. museugoeldi from French Guyana.

Describimos una nueva Caecilia proveniente del Parque Nacional Natural Yaigojé Apaporis, Taraira, Vaupés, Colombia, en cercanías de la frontera brasilera. Si bien solo se conocen tres ejemplares de esta especie, esta es reconocible entre todos sus congéneres por la forma de su cabeza, su dentición, sus conteos de surcos primarios y secundarios, sus escamas dérmicas ovaladas y por su pequeño escudo terminal. Aunque sus relaciones filogenéticas se desconocen, esta resulta más similar a C. museugoeldi de Guyana Francesa.

Males of the Strawberry Poison Frog (Oophaga pumilio) use acoustic signals during courtship and territorial interactions. In these contexts, spectro-temporal characteristics of the calls provide information on body size, territory quality, and dominance to conspecifics. Previous research on this species has associated low-rate territorial calls produced by resident males with greater aggressiveness. However, how variation in call rate of intruding males affects the response of the territorial males has not been tested experimentally. We evaluated the effect of different call-rate stimuli (low, average, and high call rate) on the acoustic and behavioral responses of territorial males of the Strawberry Poison Frog using playback experiments to simulate territorial male intrusions. We found that territorial males lowered their call rate in response to playbacks with high and average call rate. In addition, territorial males approached three times more, closer, and faster to the average and low call-rate playback stimuli than to high call-rate stimulus. Males also responded, vocalizing faster to the average and low call-rate playback stimuli than to high call-rate stimulus. Our results suggest that different call rates correlate with different levels of aggressiveness in males of the Strawberry Poison Frog. Therefore, the observed behavior supports the hypothesis that a low call rate indicates higher aggressiveness in male–male interactions.

A new species of the scaleless black dragonfish genus Melanostomias is described based on a single specimen (180 mm SL) collected off the northern Fernando de Noronha Archipelago (Brazil), western Tropical Atlantic. It differs from its congeners in having a unique barbel morphology, which ends in a bulb with two opposite slender terminal appendages. In addition, the occurrences of Melanostomias melanops and M. valdiviae are confirmed in Brazilian waters based on examination of new material. An overview analysis of the distribution and meristic variation of the species within the genus is also provided.

Labeotropheus is a small genus of rock-dwelling haplochromine cichlid fishes endemic to Lake Malaŵi in the Great East African Rift Valley. As currently recognized, Labeotropheus contains five species: L. artatorostris, L. chlorosiglos, L. fuelleborni, L. simoneae, and L. trewavasae. Despite increased recent attention from taxonomists, there are still several undescribed species within this genus. Here, based upon morphological and meristic data, as well as differences in male nuptial color pattern, we describe six new species. Additionally, we update the type locality of L. simoneae. The descriptions of these new species are in line with current recommendations to better define and delimit the taxonomy of cichlids from Lake Malaŵi, which will hopefully lead to increased efforts to conserve these fishes.

The family Serranidae comprises a large group of marine fishes distributed worldwide. The identification of early stages of serranids at the species level is difficult due to a high family diversity and to overlapping morphological and meristic features. In this study, we describe morphological and meristic features of early stages of Dules auriga and summarize density and distribution data for larvae collected in the San José Gulf, Península Valdés, Argentina. Larvae were distinguished by relevant morphological features that include opercular complex development, meristic features, pigmentation pattern, the sequence of appearance of fin elements, and the structure of the caudal region, typical of serranids. The elongated third dorsal spine, characteristic of adult D. auriga, was not observed. Two preflexion larvae were identified using COI barcoding to confirm the species identity. Morphological features described here helped to discriminate D. auriga from other serranids occurring in the area and enabled reconstruction of the entire developmental series and linkage between early stages and adults.

La familia Serranidae incluye un gran número de peces marinos distribuidos en todo el mundo. La identificación de los primeros estadios de esta familia a nivel de especie resulta dificultoso debido a su gran diversidad, y al solapamiento en los caracteres morfológicos y merísticos entre especies. En este estudio se describen las características morfológicas y merísticas de los primeros estadios de Dules auriga y se presenta información sobre su densidad y distribución en el golfo San José, Península Valdés, Argentina. Las larvas fueron identificadas a partir de rasgos morfológicos entre los que se encuentran el desarrollo del complejo opercular, los caracteres merísticos, el patrón de pigmentación, el orden de aparición de los radios y espinas en las aletas y la estructura de la región caudal, la cual es la típica de los serránidos. La tercera espina dorsal alargada, característica en adultos de D. auriga, no fue observada. Por otro lado, se confirmó la identidad de dos larvas en preflexión utilizando el código de barras genético para el gen COI. Las características morfológicas descriptas en este estudio son útiles para distinguir a D. auriga de otros serránidos presentes en el área. Dichos caracteres permitieron reconstruir la serie de desarrollo completa y vincular los primeros estadios con los adultos.

Five species of Glyptothorax are identified from the Mae Klong River basin in western Thailand, only one of which, G. buchanani, was previously reported from the basin; others are G. lampris, G. longinema, G. platypogonides, and G. schmidti. The morphological differences delineating species of Glyptothorax in the Mae Klong were visualized using principal component analysis of data taken from 105 specimens, and the latitudinal range and number of river basins over which all occur were found to be greater than previously recognized. Glyptothorax platypogonides, recently thought to range only as far north as peninsular Thailand, occurs in the Mae Klong and Chao Phraya basins in western and northern Thailand. Glyptothorax schmidti, thought to occur only as far north as the Tanintharyi River, Myanmar, was found to be much more wide-ranging, with the inclusion of populations in the Mae Klong, Chao Phraya, and Mekong River basins. Glyptothorax longinema was found to occur outside of China in lower portions of the Salween River basin and in the Mae Klong basin. The presence of G. lampris in the Chao Phraya is questioned and its southern distributional limit was extended to the Tapi River basin. Phylogenetic reconstruction of COI sequence data for 127 individuals from across Southeast Asia revealed strong BI and ML support for recognition of 14 species in Thailand and suggested deep-rooted clades that are discussed as corresponding broadly to body coloration. Glyptothorax callopterus was found to be genetically distinct from G. fuscus and is resurrected from synonymy. A key to all species of Glyptothorax in Thailand is provided.