Prognathodes geminus, a new species of butterflyfish (Teleostei, Chaetodontidae) from Palau

A new species of the butterflyfish genus Prognathodes (Chaetodontidae) is described from two specimens collected at a depth of 116 m off Ngemelis Island, Palau. Prognathodes geminus sp. n. is similar to P. basabei Pyle & Kosaki, 2016 from the Hawaiian archipelago, and P. guezei (Maugé & Bauchot, 1976) from the western Indian Ocean, but differs from these species in the number of soft dorsal-fin rays, size of head, body width, and body depth. There are also subtle differences in life color, and substantial differences in the mtDNA cytochrome oxidase I sequence (d ≈ 0.08). Although genetic comparisons with P. guezei are unavailable, it is expected that the genetic divergence between P. guezei and P. geminus will be even greater than that between P. geminus and P. basabei. It is named for the strikingly similar color pattern it shares with P. basabei

Geopolitical species revisited: genomic and morphological data indicate that the roundtail chub Gila robusta species complex (Teleostei, Cyprinidae) is a single species

The Gila robusta species complex in the Lower Colorado River Basin has a complicated taxonomic history. Recent authors have separated this group into three nominal taxa, G. robusta, G. intermedia, and G. nigra, however aside from location, no reliable method of distinguishing individuals of these species currently exists. To assess relationships within this group, we examined morphology of type specimens and fresh material, and used RADseq methods to assess phylogenetic relationship among these nominal species. Maximum likelihood and Bayesian inference tree building methods reveal high concordance between tree topologies based on the mitochondrial and nuclear datasets. Coalescent SNAPP analysis resolved a similar tree topology. Neither morphological nor molecular data reveal diagnostic differences between these species as currently defined. As such, G. intermedia and G. nigra should be considered synonyms of the senior G. robusta. We hypothesize that climate driven wet and dry cycles have led to periodic isolation of population subunits and subsequent local divergence followed by reestablished connectivity and mixing. Management plans should therefore focus on retaining genetic variability and viability of geographic populations to preserve adaptability to changing climate conditions

Taxonomy based on science is necessary for global conservation

Peer reviewe

PHYLOGEOGRAPHY AND EVOLUTION OF MESOPHOTIC CORAL ECOSYSTEMS

Ph.D

Shifting reef fish assemblages along a depth gradient in Pohnpei, Micronesia

Mesophotic coral ecosystems (MCEs) continue to be understudied, especially in island locations spread across the Indo-Pacific Ocean. Pohnpei is the largest island in the Federated States of Micronesia, with a well-developed barrier reef, and steep slopes that descend to more than 1,000 m. Here we conducted visual surveys along a depth gradient of 0 to 60 m in addition to video surveys that extend to 130 m, with 72 belt transects and 12 roving surveys using closed-circuit rebreathers, to test for changes in reef fish composition from shallow to mesophotic depths. We observed 304 fish species across 47 families with the majority confined to shallow habitat. Taxonomic and trophic positions at 30 m showed similar compositions when compared against all other depths. However, assemblages were comprised of a distinct shallow (30 m) group, suggesting 30 m as a transition zone between these communities. Shallow specialists had a high probability of being herbivores and deep specialists had a higher probability of being planktivores. Acanthuridae (surgeonfishes), Holocentridae (soldierfishes), and Labridae (wrasses) were associated primarily with shallow habitat, while Pomacentridae (damselfishes) and Serranidae (groupers) were associated with deep habitat. Four species may indicate Central Pacific mesophotic habitat: Chromis circumaurea, Luzonichthys seaver, Odontanthias borbonius, and an undescribed slopefish (Symphysanodon sp.). This study supports the 30 m depth profile as a transition zone between shallow and mesophotic ecosystems (consistent with accepted definitions of MCEs), with evidence of multiple transition zones below 30 m. Disturbances restricted to either region are not likely to immediately impact the other and both ecosystems should be considered separately in management of reefs near human population centers