Highly Diverse Symbiodiniaceae Types Hosted by Corals in a Global Hotspot of Marine Biodiversity.

Symbiotic dinoflagellates in the genus Symbiodiniaceae play vital roles in promoting resilience and increasing stress tolerance in their coral hosts. While much of the world's coral succumb to the stresses associated with increasingly severe and frequent thermal bleaching events, live coral cover in Papua New Guinea (PNG) remains some of the highest reported globally despite the historically warm waters surrounding the country. Yet, in spite of the high coral cover in PNG and the acknowledged roles Symbiodiniaceae play within their hosts, these communities have not been characterized in this global biodiversity hotspot. Using high-throughput sequencing of the ITS2 rDNA gene, we profiled the endosymbionts of four coral species, Diploastrea heliopora, Pachyseris speciosa, Pocillopora acuta, and Porites lutea, across six sites in PNG. Our findings reveal patterns of Cladocopium and Durusdinium dominance similar to other reefs in the Coral Triangle, albeit with much greater intra- and intergenomic variation. Host- and site-specific variations in Symbiodiniaceae type profiles were observed across collection sites, appearing to be driven by environmental conditions. Notably, the extensive intra- and intergenomic variation, coupled with many previously unreported sequences, highlight PNG as a potential hotspot of symbiont diversity. This work represents the first characterization of the coral-symbiont community structure in the PNG marine biodiversity hotspot, serving as a baseline for future studies.

Etmopterus samadiae n. sp., a new lanternshark (Squaliformes: Etmopteridae) from Papua New Guinea.

A new species of lanternshark, Etmopterus samadiae (Squaliformes: Etmopteridae), is described from off northern Papua New Guinea, in the western Central Pacific Ocean. The new species resembles other members of the "Etmopterus lucifer" clade in having linear rows of dermal denticles and most closely resembles E. brachyurus from the western North Pacific. The new species occurs along insular slopes between 340 and 785 m depth. The new species can be distinguished from other members of the E. lucifer clade by a combination of characteristics, including length of anterior flank branch markings being slightly shorter than its posterior branch, a longer caudal base marking, and irregular and variable number of black, horizontal, dash-like marks on sides of body. Molecular analysis based on the NADH2 marker further supports the distinction of E. samadiae from other members of the E. lucifer clade.

A new species of velvet skate, Notoraja sereti n.sp. (Rajiformes: Arhynchobatidae) from Papua New Guinea.

A new arhynchobatin skate, Notoraja sereti n. sp., is described based on three specimens collected from off Madang (Papua New Guinea) at depths of 800-980 m. This medium-size Notoraja skate shares with other velcro skates from the Western Pacific, N. alisae, N. fijiensis, N. inusitata and N. longiventralis, a ventral surface covering of fine denticles giving the skin a velvety feel. Notoraja sereti differs from all of these species in having a shorter snout (preorbital length 10.1-11.1 vs. 11.5-14.5% TL, prenasal length 8.2-8.9 vs, 9.8-12.1% TL), shorter head (dorsal head length 15.2-16.2 vs. 17.1-19.3% TL, ventral head length 21.6-22.9 vs. 22.9-25.9% TL), fewer pectoral-fin radials (total radials 58-60 vs. 61-74), and fewer vertebrae (predorsal diplospondylous centra 66-71 vs. 72-82, predorsal centra 90-95 vs. 98-107, total centra 126-131 vs. 135-152).

Galeus corriganae sp. nov., a new species of deepwater catshark (Carcharhiniformes: Pentanchidae) from Papua New Guinea.

A new species of catshark, provisionally placed in the genus Galeus, is described from Papua New Guinea based on 7 specimens collected during recent deepwater surveys of the region. The new species, Galeus corriganae, is closest to G. priapus from New Caledonia and G. gracilis from northwestern Australia but differs in several morphological characters. A reclassification of the catshark groups is required to revise the familial and generic arrangement of the group.