Euchone Malmgren, 1866
Euchone sp. 3
Voucher specimens. VINSON WEST: station 5MFA.
Diagnosis. Small bodied, slender species; voucher specimen with body complete, but branchial crown missing; 2.2 mm long (body) and 0.2 mm wide, with 8 thoracic and 22 abdominal chaetigers with 5 of these associated with pre-pygidial depression; colour in alcohol pale yellow.
Collar well developed; of similar height all around, only slightly higher ventrally than dorsally; with mid-dorsal margins overlapping; anterior margin entire ventrally with a shallow mid-ventral notch. Glandular ridge present on chaetiger 2, very narrow.
Collar chaetae narrowly-limbate arranged in single longitudinal, somewhat oblique row; superior and inferior notochaetae of similar type, limbate, 3 + 3 per fascicle. Thoracic neuropodial uncini acicular, about 10 per fascicle in chaetiger 1 (first thoracic unciniger) and 4 in the last thoracic chaetiger. Companion chaetae absent. Abdominal neuropodial chaetae few, narrowly-limbate. Notopodia of anterior abdominal chaetigers with quadrate avicular uncini, with well developed breast and very short handle.
Abdomen with a narrow pre-pygidial depression occupying 5 (the last two very small, can be overlooked) chaetigers, with high raised membranous lateral flanges connected anteriorly by a rounded membrane, flanges lower posteriorly. Pygidium very large (in comparison to small body size), longer than wide, triangular lobe (stains strongly with methyl green). Tube not observed.
Mehtyl green staining pattern: refer to plate accompanying this description.
Remarks. A commonly reported species from the region Euchone pallida described by Ehlers (1908) has been already discussed in Remarks section of Euchone sp. 1 and 2. Euchone sp. 3 is another small bodied Euchone species collected from Falkland Islands, which can be distinguished by possessing a rather large (relative to its body size) pygidial lobe, which stains strongly.
