| Summary: | Microthalestris polaris sp. nov. urn:lsid:zoobank.org:act: 2DD62715-A421-471B-A3A0-83EF1A166B81 Parastenhelia spinosa (Fischer, 1860) sensu Chislenko (1967, 1977), Mielke (1974) Both M. forficuloides and M. sarsi sp. nov. display the maximum number of eight setae/spines on the female P5 exopod. This number has also been observed in females assigned to M. forficula by Wilson (1932b), and to Parastenhelia spinosa by Chislenko (1967, 1977), Mielke (1974) and Kornev & Chertoprud (2008). Wilson’s (1932b) description is concise, illustrating only P1, P5 of both sexes and male P3 endopod. Differences in body size (distinctly smaller – see above), P1 endopod (proximal segment comparatively longer so that exp-2 is only about 40% the length of enp-1 and the insertion point of the inner seta of enp-1 is located at 17% of the inner margin length), male P3 endopod (with inner seta on enp-3), and the male P5 (with long outer seta on exp-1) rules out conspecificity of the Woods Hole material with M. sarsi sp. nov. Since information about the segmentation of the female antennule, swimming leg armature and morphology of caudal ramus seta V is completely lacking, Wilson’s (1932b) material cannot be attributed distinct specific status at present and is therefore not considered any further. Conversely, the three illustrated reports based on material from Arctic localities (Chislenko 1967, 1977; Mielke 1974) contain sufficient information for a morphological comparison with M. sarsi sp. nov. Based on the descriptions by Chislenko (1967) and Mielke (1974), the Arctic specimens differ from the latter species in the following combination of characters: (a) antennary exopod with two lateral setae on exp-2 ( vs one); (b) P1 exopod 75% length of endopod ( vs two-thirds); (c) P3–P4 exp-3 with three inner setae ( vs two); and (d) male P5 exopod with very long outer seta on exp-1 ( vs absent or extremely reduced). They also can be distinguished from M. forficuloides by a number of features: (a) antennary exopod with two lateral setae on ...
|
|---|