Austropallene halanychi: A new species of Pycnogonid 'Sea Spider' from the Ross Sea, Antarctica.

Pycnogonid 'Sea Spiders' are a distinctive group of marine Arthropods, thought to be either members of the Chelicerata (the group which also includes Arachnids, Horseshoe Crabs, and the extinct Eurypterid Sea Scorpions), or a basal Arthropod group, forming the sister group to all other living Arthropods. Pycnogonids have four (or sometimes five) pairs of long legs emerging from a very small body, The head has a distinct proboscis which allows them to suck nutrients from soft-bodied Animals, as well as ocular tubercle with eyes, and up to four pairs of appendages, from front to back the chelifores, the palps, the ovigers (used for cleaning themselves and caring for eggs and young), and the first pair of walking legs. About 1300 species of extant Pycnogonids are known, most of which are very small (to the extent that the leg muscles in some species comprise a single cell), although some deep water and Antarctic species get quite large, with the largest having a leg span of over 70 cm.

In a paper published in the journal ZooKeys on 28 November 2023, Jessica Zehnpfennig and Andrew Mahon of the Department of Biology at Central Michigan University, describe a new species of Pycnogonid from the Ross Sea, Antarctica.

The new species is placed in the genus Austropallene, and given the specific name halanychi, in honour of Kenneth Halanych, a marine biologist whose commitment and dedication to the benthic marine systems in the Southern Ocean has provided a wealth of information related to biodiversity in the Antarctic system. It is described from a single male specimen, collected by benthic trawl from the RVIB Nathaniel B. Palmer on 31 January 2023.

Austropallene halanychi, male holotype. (A) Dorsal view. (B) Dorsal-frontal view; note shape, relative size, and black tips of chela fingers, cephalic spurs, and eye tubercle and eyes; note sharp conical outgrowths at base of fixed and movable fingers of chelifores (red arrow). Zehnpfennig & Mahin (2023).

The single known specimen of Austropallene halanychi was collected from a depth of 570 m on the Ross Shelf seafloor. It is 10.5 mm in length with walking legs up to 28.78 mm long. Its body is slender with a fully segmented trunk, a distinct neck, The abdomen is short, and the proboscis is directed downwards and tapers to a point. Four eyespots are present. 

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