Comprehensive DescriptionRead full entry
“Macromckenziea glacierae new species
Graph 8; fig. 4.14, 15, 5.13, 14, 18.13, 24.19, 25.7, 8, 29.1, 32.2, 36-37.8, 46.20-25, 54.44-46, 55.38-40, 56.25, 31, 57.26, 34, 58.5, 59.16, 30, 60.1, 63.9, 64.48-50, 66.2, 71.1, 75.1, 78.3; Plates 8.3-6, 9.3-6, 65.7-10, 78.16, 17, 83.3, 86.5-9, 100.1-6, 110.5, 7
Derivation of name – For the U.S. Coast Guard Ship Glacier.
Material – Forty-two specimens in alcohol, including 7 males, 17 females, 14 juveniles belonging to 3 instars, and 4 carapaces and valves.
Types – Holotype male 880M USNM 240349, paratypes USNM 240350-240370.
Type locality – Glacier cruise 1 station 0001, 74°06’-07’S, 39°38’W, depth 400 fathoms (732m).
Occurrence – At GL-1-0001, 17 live plus 3 specimens (6M, 7F, 1FJ-1, 1MJ-2, 2FJ-3); at GL-2-004, 5 live plus 1 specimen (1F); at E-6-412, 2 live specimens (2F); at E-22-1535, 1 live specimen (1M); at Y-2-6, 7 live specimens (1F, 6J-1); at V-14-21, 5 live specimens (5F).
Distribution – Holocene; Drake Passage and Weddell Sea, Antarctica, known live depth range 97-3111 m. Hartmann (1987) reported it living at eight stations in the South Shetland Islands and the Palmer Archipelago at depths between 140 and 180 m.
Dimensions – Holotype male 880M, RVL 1.82 mm, RVH 0.77 mm, LVL 1.78 mm, LVH 0.73 mm. Females longer, higher, and proportionally higher than males. See also Graph 8.
Diagnosis – Right valve elongate-subtriangular in outline, with broadly arched dorsal margin and without distinct dorsal or posterodorsal angles; greatest height located medially, sloping smoothly to narrowly but evenly rounded anterior margin and steep posterior margin; ventral margin nearly straight; posteroventral angle distinct, located ventrally, about 70° to 80°.
Palp of male fifth limb robust with prominent sensory seta and slender pegs of unequal size; left hook strongly recurved. Palp of female fifth limb with extremely long middle distal seta. Sixth limb has two distal claws of equal length. Reflexed seta of seventh limb very short but conspicuously feathered; mediodistal seta very long. Furca vestigial in both sexes; distal region and terminal seta entirely missing; proximal region reduced to a very tiny nub with four tiny proximal setae. Hemipenis rounded-subtriangular in lateral view, higher than long, without conspicuous anterior lobe; copulatory tube very long and coiled. Anterior bulb of Zenker’s organ enlarged, muscular segment fairly long; vas deferens regularly coiled in circular disk of about four loops.
Comparisons – In shape Mk. Glacierae is most similar to Mk. Gregalis, but it is very much smaller and more elongate. The reduced furca and other soft-part characters support its classification in Macromckenziea.” (Maddocks 1990, p.51-52)