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| Hedgpethia filamentus
Staples, 2019
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Abstract
This report addresses sixty-two deep-sea pycnogonid specimens collected by the Southwest Indian Ocean Seamounts Expedition, November 7 to December 21, 2011 on-board the British research vessel R.S.S. James Cook (voyage numbers JC066, JC067). Pycnogonids were collected from four of six geological features sampled along the central section of the Southwest Indian Ridge (SWIR) in an area approximately 1500 km south-south east of Madagascar. Specimens were mostly gathered utilizing a remotely operated vehicle (ROV) and tethered video-sediment grab platforms. Additional specimens were gathered from sediment cores or hand-picked from whale bone and wood-fall experiment nets and mooring buoy ropes. Fifteen new species are described, illustrated and compared with their nearest relatives. Two previously described species belonging to the genera Colossendeis and Austrodecus are recorded. A specimen of Austrodecus bamberi represents the first record of the female and is the only species in the collection previously known from the SWIR. One species of Colossendeis remains unnamed pending further analysis. One subadult specimen of Sericosura showing strong morphological affinity with a specimen previously recorded from the Walvis Ridge remains undescribed pending availability of further material. One subadult specimen is tentatively assigned to Nymphon. Specimens are assigned to six families and eight genera. Colossendeis rostrata is synonymised with C. melancholicus. The methodology of counting palp segments in the genera Austrodecus and Rhynchothorax is reviewed.
Keywords: Southwest Indian Ridge, RV James Cook, seamounts, new species, new records, Austrodecus, Colossendeis, Hedgpethia, Nymphon, Pycnogonum, Rhynchothorax, Sericosura, Tanystylum, Longqi/Dragon hydrothermal vent field, whale bone and wood-fall moorings, hydroids
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| Hedgpethia filamentus sp. nov., holotype;
with proboscis inserted into Isactinernus quadrilobatus.
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Systematics
• Family Nymphonidae Wilson, 1878Genus Nymphon J.C. Fabricius, 1794
Nymphon rogersi sp. nov.
Nymphon serpettiae sp. nov.
Nymphon dentatum sp. nov.
Nymphon gravidus sp. nov.
• Family Ammotheidae Dohrn, 1881
Genus Tanystylum Miers, 1877
Subgenus Achelinae Sabroux et al., 2017
Tanystylum lamonti sp. nov.
Tanystylum tiara sp. nov.
Genus Sericosura Fry & Hedgpeth, 1969
• Family Austrodecidae Stock, 1954
Genus Austrodecus Hodgson, 1907
Austrodecus bamberi Wang et al., 2013
Austrodecus taylorae sp. nov.
Austrodecus sp. C
• Family Rhynchothoracidae Thompson, 1909
Genus Rhynchothorax Costa, 1861
Rhynchothorax swir sp. nov.
Rhynchothorax coralensis sp. nov.
• Family Colossendeidae Hoek, 1881
Genus Colossendeis Jarzynsky, 1870
Colossendeis sp.
Colossendeis melancholicus Stock, 1974
Genus Hedgpethia Turpaeva, 1973
Hedgpethia filamentus sp. nov.
Hedgpethia shalei sp. nov.
• Family Pycnogonidae Wilson, 1878
Genus Pycnogonum. Brünnich, 1764
Pycnogonum sentus sp. nov.
Pycnogonum (Pycnogonum) copleyi sp. nov.
Pycnogonum cheni sp. nov.
David A. Staples. 2019. Pycnogonids (Arthropoda, Pycnogonida) from the Southwest Indian Ridge. Zootaxa. 4567(3); 401–449. DOI: 10.11646/zootaxa.4567.3.1
