Amphicorina Claparède, 1864
Oriopsis Caullery and Mesnil, 1896
Amphicorina sp. 3
Voucher. VINSON WEST: station 1MFB.
Diagnosis. Small, but robust species; voucher specimen with body complete, branchial crown missing; body 2mm long (body only) and 0.5mm wide; with 8 thoracic and 13 abdominal segments.
Collar as an enlarged lobe, wide ventrally, low laterally and dorsally; margin smooth, entire (not notched) ventrally; laterally and dorsally smooth but bent into slight folds; not forming pockets dorsally, not overlapping at dorsal midline; peristomial eye not observed. Glandular ridge on 2 present.
In thorax, mucronate chaetae absent, only limbate (hooded) notochaetae present, about 7 per fascicle; thoracic uncini acicular, up to 8 per fascicle. Abdominal neurochaetae few, narrowly limbate; abdominal uncini rasp-shaped plate, with about 7-8 vertical rows of very small teeth (about 10 per row) above the main fang, up to 9 per ramus,.
Pygidium large triangular lobe, slightly longer then wide; pygidial eyes not observed.
Methyl Green pattern: see image.
Remarks. Of Amphicorina species known from the area (see Table below), FI specimens are most similar to A. kocki (Hartmann-Schröder and Rosenfeldt, 1989) described from 68m at Bransfield Straits and A. pulchra from Elephant Is., 134-370m, which both possess similar number of abdominal segments. The specimens agree in terms of its body shape and shape of peristomial collar. However they differ in number and form of abdominal uncini (see comparative table below). The branchial crown is missing in FI specimens and characters derived from this feature cannot be compared. Other species belonging to genus Amphicorina known from the area possess much smaller number of abdominal segments (see comparative table below).
Overview of Amphicorina species known from Magellan region, Chile and Southern Ocean (comparative table of all species of Amphicorina can be found in Giangrande et al. (2009)).
|
No. of abdominal segments (variation) |
Max. no of uncini per ramus/Form of abdominal uncini |
Type locality and depth |
|
|
A. magellanica |
9 |
up to 11/13 teeth above basal prow (in lateral view) |
Straits of Magellan - Tierra del Fuego; 3-4m |
|
A.taltalensis |
5 |
up to 9/7-9 teeth above basal prow (in lateral view) |
near Taltal, Chile |
|
A. alatoides |
11 |
up to 14/12-13 teeth above basal prow (in lateral view) |
from rockpool at Huasco |
|
A. limbata (with eyes) |
5-6 |
up to 20/8 vertical rows (in frontal view), with about 12 teeth in each row |
South Patagonia |
|
A. kocki |
13 (9-13) |
up to 16/4-5 vertical rows (in frontal view), with about 10 teeth in each row |
Bransfield Strait, 68m |
|
A. longipyge |
5 |
up to 12/3-4 vertical rows, with about 11 teeth in each row |
Point Thomas, Southern Ocean, 50-133m |
|
A. pulchra |
14 (11-14) |
up to 5/6-7 vertical rows (in frontal view), with about 6 teeth in each row |
Elephant Is., 134-370m |
|
A. alata (collar absent) |
6 |
? |
South Georgia, littoral |
|
A. magna |
5 |
up to 20/ 5-6 rows of 12 teeth in each row |
South Georgia |