The taxonomic classification of sea spiders (Arthropoda: Pycnogonida) includes 11 distinct families, mostly characterized by different combinations of presence/absence of the cephalic appendages, the characters they display (number of articles, terminal claw, distribution of spines, etc.), and the position of gonopores in both sexes and of the cement gland pores in males. However, about 20 nominal species could not be confidently classified, and a few others were only tentatively assigned to one of these families. These taxa represent an interesting challenge to review, reshape and expand the Pycnogonida taxonomy, and thus to apprehend more comprehensively the phylogeny of the group. In this contribution, Maageninum kanakorum gen. nov., sp. nov. is described based on two males and two females that were sampled at 220-232 m depth in a single location off southeast of New Caledonia in 2011 during the EXBODI expedition (Tropical Deep-Sea Benthos program). A fragment of the gene coding for the first unit of the cytochrome oxidase was sequenced for three of these specimens for the purpose of DNA barcoding, and the gonopores were investigated in both sexes through scanning electron microscopy. Due to its unique combination of characters, the genus Maageninum cannot be confidently attributed to any of the known pycnogonid families based on the sole morphological characters: absence of chelifores; palps reduced to two articles only present in males; ovigers two-articled in males, or reduced to a conspicuous unarticulated bud in females; gonopores carried on the ventral surface of coxae 2 in legs 2-4, both in males and females. For this reason, it is to be regarded as incertae sedis until its position is resolved by future phylogenetic studies.
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