Capitella Blainville, 1828
Capitella sp. 1
Voucher. SEA LION: station 2MFA
Diagnosis. Small-sized, slender species; voucher is a small, incomplete specimen, fragment about 2.7mm long and 0.25mm wide (at the widest part of thorax) for about 14 chaetigers; first 4 chaetigers with notochaetae only; from chaetiger 5 hooded hooks only; genital spines not observed. Body cylindrical, widest across chaetiger 5-6 (forming a “bump” effect) tapering in chaetigers 7-9; abdomen abruptly narrowing, slender. Segments in thorax short. Segments in abdomen elongated, with 3 annuli per segment, each annulus about as long as wide. Colour in alcohol tan. Prostomium broad, bluntly rounded on anterior margin, as wide as long, thick, flattened. Peristomium simple incomplete achaetigerous ring, prominent dorsally and laterally, merging into oral opening ventrally, becoming roof of mouth; eyes absent.
Chaetigers 1-4 with notochaetae only in both rami; notochaetae capillaries, unilimbate with narrow wings. From chaetiger 5 multidentate hooded hooks only in both rami; hooks with at least 3 rows of denticles above main fang observed in profile with wide gap between the main fang and first small denticle above it; about 6 hooks per ramus. Abdomen damaged, pygidium unknown.
Remarks. At least 3 species of Capitella were encountered in Falkland Island material. These are here distinguished by the body shape and form of multidentate hooks (see comparative table below). Assigning those specimens to any previously reported species from the region will be difficult as great variation can be encountered in a single species (see Blake, 2009 for re-description of Capitella capitata). Molecular studies will be needed to help resolve the status of Capitella species in Falkland material and here will be assigned to morphospecies only.
Comparison of species assigned to genus Capitella, collected from Falkland Islands in this study.
|
Body shape |
No. of chaetigers with notochaetae only |
Number of abdominal hooks per ramus |
Form of abdominal hooks (in profile) |
|
|
Capitella sp. 1
|
Overall slender: thorax wide, with chaetigers 5-6 widest (forming a “bump”; abdomen tapering abruptly, slender |
4 |
About 6 |
At least 3 denticles above main fang with wide gap between the main fang and first small denticles above it |
|
Capitella sp. 2
|
Overall slender: thorax wide, without a prominent “bump”; abdomen tapering gradually |
7 |
About 5 |
At least 6 denticles above main fang all closely together |
|
Capitella sp. 3
|
Overall robust: Body cylindrical, of nearly uniform width, abdomen only slightly tapering |
7 |
About 10 |
With many denticles above main fang all closely together |
