Amphicorina Claparède, 1864
Oriopsis Caullery and Mesnil, 1896
Amphicorina sp. 2
Voucher. SEA LION: station 50MFC.
Diagnosis. Small and slender species; voucher specimen complete, with branchial crown; body 1.7 mm long, crown 0.8 mm long, body 0.25 mm wide; with 8 thoracic and 5 short (much wider than long), crowded abdominal segments.
Branchial crown with 3 pairs of radioles; non-vascularized ventral filaments not observed. Distal end of radioles filamentous, without papillae. Collar most developed ventrally as a high lobe, laterally and dorsally as a low lobe; margin smooth with mid-ventral shallow notch; dorsally not forming pockets, not overlapping at midline. Peristomial eyes not observed. Glandular ridge on chaetiger 2 present.
In thorax mucronate chaetae absent, only limbate (hooded) notochaetae found, around 7 per fascicle; thoracic uncini acicular, up to 5 per fascicle, with the larger tooth above the main fang displaced and followed by few small teeth. Abdominal neurochaetae, few, narrowly limbate capillaries. Abdominal uncini rasp-shaped, up to 12 per ramus, arranged in about 6 vertical rows with many (about 20) small teeth per row.
Pygidium triangular lobe, slightly longer than wide; pygidial eyes not observed.
Remarks. Genus Amphicorina is species rich in the geographical area investigated here, with 9 species reported in literature. The two species reported from FI here are likely to be new species. Of the known species from the geographical area investigated, three Amphicorina species have 5 abdominal segments: A. taltalensis, A. longipyge and A. magna (see table below). Falkland Is. specimens differ in having abdominal uncini with very numerous (around 20) small teeth per each of 6 rows. Other known species have fewer, around 10 (7-12) small teeth per row.
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 |