The devil is coming: Feeding behavior of juvenile Munk’s devil rays (Mobula munkiana) in very shallow waters of Punta Descartes, Costa Rica

Introduction: Identifying critical habitats for vulnerable elasmobranch species is crucial for effective conservation measures. The Munk’s devil ray (Mobula munkiana) is endemic to the Eastern Pacific, but yet little is known about its biology, ecology, and habitat use. As filter feeders, it is assumed that this species concentrates at high-productive upwelling regions, such as the Costa Rican Dome. Like many elasmobranchs, its populations are highly depleted and require urgent information to inform better conservation measures. Objective: The study was conducted to gain information on a unique behavior observed in juvenile M. munkiana, so further information can be provided on early life stages of this vulnerable species. Methods: From June to September 2017 and in August 2018, the feeding behavior of juvenile Mobula munkiana was observed in two shallow bays located at Punta Descartes, North Pacific Costa Rica. Individuals were captured using a non-lethal method to obtain data on size, weight, and sex distribution. Plankton samples (n = 100) were taken at both bays throughout the months to infer diet composition. Results: Munk’s devil rays showed a repetitive swimming movement parallel to the beach, feeding exclusively in the shallow breaking zone of the low tide waves at depth <50cm. A total of 12 M. munkiana (11 live and one found dead) indicated a juvenile feeding aggregation ranging from 490 – 610mm in disk width and 1400 – 2300gr in weight. The sex ratio (males to females) was 3:1. Zooplankton of the order Mysidacae was found in the highest abundance in the breaking zone. Conclusions: The specific behavior and seasonal occurrence of juvenile Munk’s devil rays in this area seem to be driven by prey abundance. More research is needed to conclude the presence of reproductive adults at deeper depths and the year-round habitat use of Punta Descartes. The area is threatened by unsustainable development and requires realistic management strategies to guarantee the survival of vulnerable species and their critical habitats.

First confirmed record of the occurrence of the lesser devil ray, Mobula hypostoma (Elasmobranchii, Mobulidae), in the southwestern Gulf of Mexico

Nine specimens (one female and eight males, all juveniles) of lesser devil ray, Mobula hypostoma (Bancroft, 1831), were caught in the southwest Gulf of Mexico. These specimens represent the first record of the species in the Mexican waters. The disk width ranged between 552 and 773 mm. Morphometrics data are consistent with previously published records. Because of the number of specimens captured, we suggest that it is not a rare species in the southwest Gulf of Mexico.

Dancing with the devil: courtship behaviour, mating evidences and population structure of the Mobula tarapacana (Myliobatiformes: Mobulidae) in a remote archipelago in the Equatorial Mid-Atlantic Ocean

The present work aimed at studying the sicklefin devil ray (Mobula tarapacana) that aggregates seasonally in the Saint Peter and Saint Paul Archipelago (SPSPA). From December 2008 to June 2016, 827 rays were sighted through free diving visual census survey. From the total of the records, it was possible to identify the sex of 361 specimens, in which 215 were females and 146 were males. The disk width ranged from 2.40 m to 3.20 m with mean size of 2.60 m, for both males and females, indicating that the population is composed by sub-adults and adults. Using photo-identification of the pectoral-fins in the ventral side, 11 males and 44 females were identified and compared with each other, but no re-sight was detected. Recent mating scars were observed in males (n= 7) and females (n= 6), as well as courtship and pursuit behaviors, confirming that the SPSPA is an important area of aggregation and mating for M. tarapacana in the Atlantic Ocean.

Tadpole morphology of the white-eyed toad Leptobrachium leucops Stuart, Rowley, Tran, Le & Hoang 2011 (Anura: Megophryidae) in Bidoup – Nui Ba National Park, Lam Dong province

We describe the tadpole morphology of the white-eyed megophryd, Leptobrachium leucops Stuart, Rowley, Tran, Le & Hoang 2011 based on specimens originating from Bidoup – Nui Ba National Park, Lam Dong Province, Vietnam. The description is based on larva in developmental stages 25 - 41, which were bred at the University of Science, Vietnam National University-Ho Chi Minh City. Tadpoles of Leptobrachium leucops live in slow-flowing water - benthic with the body color from brown-black to black. Body oval shape in lateral view, dorsolaterally positioned eyes. Spiracle sinistral and leftlateral positioned. Vent tube medially located at body end, ventrally positioned. Oral disk ventrally positioned and bordered by a papillae row, in general, the keratodont row formulae of the is 1(5+5)/(4+4)1. Body length and oral disk width increase during developmental stages while tooth density decreases gradually and disappeare at the stage of 41.

Descriptions of the tadpoles of seven species of Malagasy treefrogs, genus Boophis

The genus Boophis is a species-rich group of treefrogs within the family Mantellidae Laurent, endemic to Madagascar. The larval morphology of these frogs is an important trait to understand the evolution of reproductive modes and larval morphologies in the mantellid radiation and can provide important information to compare adaptations of tadpoles and adults, and elucidate possible covariation, and convergent evolution of these traits. We here assign seven previously unknown or insufficiently described Boophis tadpoles to species via DNA barcoding, and provide detailed morphological descriptions based mainly on the unambiguously identified DNA voucher specimens. All described tadpoles are stream-adapted, exotrophic tadpoles of a relatively generalized morphology. Applying our previous classification for stream-breeding Boophis based on relative oral disk width and the number of papillae and keratodonts we attempt an assignment of all species into ecomorphological guilds. Our results show that this previous definition of guilds (in Boophis) based on only three characters was an oversimplification, and that the variation in these tadpoles is more complex. In a phylogenetic context we found that species within at least two species groups of Boophis are heterogeneous in their assignment to the ecomorphological guilds confirming the probable non-monophyly of these groups.

Ontogenetic changes in the feeding habits and dietary overlap between three abundant rajid species on the Falkland Islands' shelf

The ontogenetic changes in the diet and dietary overlap of three commercially important rajid species inhabiting the slope and shelf waters of the Falkland Islands were investigated. The white dotted skate (Bathyraja albomaculata) was a specialized amphipod and polychaete feeder. The broad nose skate (B. brachyurops) had a diverse diet, consuming a wide variety of crustaceans and fish. The grey tail skate (B. griseocauda) also had a broad diet but consumed a high proportion of amphipods and isopods (e.g. Serolis spp.). Larger individuals of the latter species were more piscivorous and consumed more squid. The diets of all three species showed a marked variation with ontogeny. Dietary overlap was greatest for smaller animals (<30 cm disk width), after which each species became more specialized in their diets. Smaller animals also showed some differences in depth of distribution, which may be an adaptation to reduce inter-specific competition.