New species of bone-eating worm Osedax from the abyssal South Atlantic Ocean (Annelida, Siboglinidae)

A new species of bone-eating annelid, Osedax braziliensis sp. n., found in a sunken whale carcass at a depth of 4,204 m at the base of the São Paulo Ridge in the South Atlantic Ocean off the Brazilian coast is described. The organism was retrieved using the human-occupied vehicle Shinkai 6500 during the QUELLE 2013 expedition. This is the 26th species of the genus and the first discovery from the South Atlantic Ocean, representing the deepest record of Osedax worldwide to date. This species morphologically resembles Osedax frankpressi but is distinguished by the presence of a yellow bump or patch behind the prostomium and its trunk length. Molecular phylogenetic analysis using three genetic markers (COI, 16S, and 18S) showed that O. braziliensis sp. n. is distinct from all other Osedax worms reported and is a sister species of O. frankpressi

Molecular Phylogeny of the Genus Nipponnemertes (Nemertea: Monostilifera: Cratenemertidae) and Descriptions of 10 New Species, With Notes on Small Body Size in a Newly Discovered Clade

Nemerteans, or ribbon worms, have been reported from intertidal to hadal depths, often showing bathymetrically wide distribution in genus levels. Although current nemertean systematics practices require to provide DNA sequences and infer phylogenetic relationships with suitable molecular markers, previous molecular systematics on nemerteans are mostly biased toward shallow-water species. Members in the genus Nipponnemertes occur worldwide, from tropical to polar waters and intertidal to bathyal waters. Molecular phylogenetic studies are scarce for the genus; only six shallow-water species of 18 species in the genus were subject to molecular phylogeny. Thus, Nipponnemertes is one candidate that needs to be assessed by genetic approaches. In this study, we performed molecular phylogenetic analyses using 59 specimens in 23 species based on partial sequences of two mitochondrial (16S rRNA and cytochrome c oxidase subunit I) and three nuclear gene markers (18S rRNA, 28S rRNA, and histone H3). Our extensive sampling from intertidal to bathyal waters in the Northwest Pacific significantly updated the fauna of Nipponnemertes in this region from four to 17 species. We herein establish 10 new species and provide an updated species list concisely summarizing all the congeners known from the world. Our phylogenetic tree indicated three major lineages within the genus (herein referred to as “Clade A, B, and C”), each presumably characterized by the combination of morphological characters in the head region. Members in Clade A are: Nipponnemertes pulchra (Johnston, 1837), Nipponnemertes ogumai (Yamaoka, 1947), and several unidentified congeners, characterized by having demarcated head without cephalic patches; members in Clade B are: Nipponnemertes crypta sp. nov., Nipponnemertes jambio sp. nov., Nipponnemertes neonilae sp. nov., and Nipponnemertes ojimaorum sp. nov., species having demarcated head with cephalic patches; members in Clade C are: Nipponnemertes ganahai sp. nov., Nipponnemertes kozaensis sp. nov., Nipponnemertes lactea sp. nov., Nipponnemertes notoensis sp. nov., Nipponnemertes ornata sp. nov., Nipponnemertes sugashimaensis sp. nov., and two unidentified forms collected off Jogashima (Japan) and Guam (USA), species with non-demarcated head lacking cephalic patches. Furthermore, we discuss the evolution of remarkably small body size retained among Clade C

A new species of the rare, deep-sea polychaete genus Benthoscolex from the Sea of Kumano, Japan (Annelida, Amphinomidae)

A new species of amphinomid polychaete, Benthoscolex seisuiae sp. n., is described from the Sea of Kumano, Japan, from depths of 487-596 m. The species is distinguishable from its congeners by the following features: i) palps 1.8 times as long as lateral antennae; ii) branchiae do not reach to the tip of the notochaetae. This is the first record of Benthoscolex from Japan. A partial mitochondrial cytochrome c oxidase subunit I gene sequence from the holotype of B. seisuiae sp. n. is provided for reliable species identification in the future

First records of Brada kudenovi Salazar-Vallejo, 2017 (Annelida, Flabelligeridae) from Japan

We reassess two specimens, part of the late Dr Minoru Imajima’s collections, from Japan of the flabelligerid genus Brada Stimpson, 1853. We re-identify the specimens as B. kudenovi Salazar-Vallejo, 2017 and newly record this species from Japan, which represents the southernmost locality of the genus worldwide. The specimens were previously reported as B. inhabilis (Rathke, 1843), which has Molde, Norway as its type locality. However, the morphological features are identical to the original description of B. kudenovi in the following: the body is whitish in alcohol; there are one or two multiarticulate notochaetae per parapodium; the neuropodial lobes are low, not projecting; and the body papillae are short

First records of Brada kudenovi Salazar-Vallejo, 2017 (Annelida, Flabelligeridae) from Japan

We reassess two specimens, part of the late Dr Minoru Imajima’s collections, from Japan of the flabelligerid genus Brada Stimpson, 1853. We re-identify the specimens as B. kudenovi Salazar-Vallejo, 2017 and newly record this species from Japan, which represents the southernmost locality of the genus worldwide. The specimens were previously reported as B. inhabilis (Rathke, 1843), which has Molde, Norway as its type locality. However, the morphological features are identical to the original description of B. kudenovi in the following: the body is whitish in alcohol; there are one or two multiarticulate notochaetae per parapodium; the neuropodial lobes are low, not projecting; and the body papillae are short

A new marine tardigrade genus and species (Arthrotardigrada, Styraconyxidae) with unique pockets on the legs

A marine heterotardigrade Cyaegharctus kitamurai gen. et sp. nov. (Arthrotardigrada, Styraconyxidae) is described from Daidokutsu, a submarine cave off Iejima island, Okinawa Islands, Ryukyu Archipelago, Japan. It is easily distinguished from all other styraconyxids by its pocket organs (putative sensory structures) on all legs in addition to the usual leg sensory organs. Its combination of other character states, such as the dorso-ventrally flattened body, ovoid primary clavae, conical secondary clavae, large terminal anus, internal digits with proximal pads and peduncles, external digits with developed peduncles and all digits with three-pointed claws in adult female, supports the erection of a new genus and species

New species of Trophoniella from Shimoda, Japan (Annelida, Flabelligeridae)

Trophoniella hephaistos sp. n. was collected from a tank irrigated with seawater pumped directly from Nabeta Bay, Japan. This species is discriminated from other Trophoniella by having dorsal tubercles, a tongue-shaped branchial plate, a tunic covered with large sediment grains dorsally and ventrally, having eyes, and anchylosed neurohooks starting from chaetigers 17–20. This is the first record of Trophoniella from Japanese waters. Identification keys to species of Trophoniella and four gene sequences (COI, 16S, 18S, 28S) of this species are provided. Phylogenetic analysis was conducted to clarify phylogenetic position of Trophoniella in Flabelligeridae using four genes

Designation of a neotype and redescription of Hesione reticulata von Marenzeller, 1879 from Japan (Annelida, Hesionidae)

The hesionid polychaete Hesione reticulata von Marenzeller, 1879 was described from Enoshima Island, Japan and has been recorded also from the Red Sea. Depending on researchers, it has been regarded as either a distinct species or synonymous with older established ones. The type specimen has been lost. In order to clarify its taxonomic status, H. reticulata is herein redescribed, illustrated, and a neotype is proposed based on recent material collected near the type locality. The diagnostic features include the presence of several dorsal, discontinuous longitudinal bands, interrupted by pale segmental spots; prostomium with tiny antennae; a tuberculated dorsal integument; acicular lobes double; and neurochaetal blades with guards approaching the distal tooth. The dorsal color pattern in life enables a clear distinction from similar species such as H. intertexta Grube, 1878 amongst others. Mitochondrial COI barcoding sequences are deposited in the DNA Data Bank of Japan. A key to Hesione species from Japan is also included

New record of the hydrothermal vent-endemic polychaete Archinome jasoni Borda et al., 2013 (Annelida, Amphinomidae) from the Northwest Pacific

The hydrothermal vent-endemic polychaete Archinome jasoni Borda et al., 2013 is known from the Atlantic, Indian, and Southwest Pacific oceans. In this study, we report A. jasoni from Okinawa Trough, Japan, which represents the first record of this species and the genus from the Northwest Pacific. We determined 16S and 28S rRNA gene sequences from 1 of the 7 specimens collected. We compared our Northwest Pacific specimens to specimens from the Southwest Pacific, Atlantic, and Indian oceans, and our specimen was genetically most closely related to individuals from the Southwest Pacific

Two new species of Branchinotogluma (Polynoidae: Annelida) from chemosynthesis-based ecosystems in Japan

Jimi, Naoto, Chen, Chong, Fujiwara, Yoshihiro (2022): Two new species of Branchinotogluma (Polynoidae: Annelida) from chemosynthesis-based ecosystems in Japan. Zootaxa 5138 (1): 17-30, DOI: https://doi.org/10.11646/zootaxa.5138.1.