Notoproctus sp. 1
Notoproctinae Detinova, 1985?
Notoproctus Arwidsson, 1907
Notoproctus sp. 1
Voucher. LOLIGO: station L 14FB.
Diagnosis. Small slender species; voucher complete (in 2 fragments); 16mm long and 0.3mm wide for 18 chaetigers. Anterior and posterior chaetiger short (about as long as wide), the mid-body chaetigers very long.
Prostomium fused to peristomium, forming a well-defined head with very low rim cephalic peak, strongly arched and rounded anteriorly. Nuchal grooves strongly curved outwards (arch-shaped). Eyes or ocelli not observed.
Notochaetae of two types - long, thick, bilimbate capillaries with fine tips, around 3 per fascicle and short, thin, distally hirsute capillaries, about 3-4 per fascicle in anterior chaetigers. Neuropodia of chaetigers 1-4 with a single, stout, acicular spine, distally blunt and rounded, dark yellow in colour. Subsequent neuropodia with row of rostrate hooks, maximum 4 per ramus, reduced to 2 in posteriormost chaetigers. Each hook with main fang and about 4 small teeth, with fibrils below the main fang; very long shaft with a pronounced localized swelling (breast).
Preanal segments without chaetae indistinct and difficult to establish (may be 2 or 3), similar to preceding chaetigers. Anal plaque present, well developed; strongly arched (perpendicular to the body) and resembles cephalic plaque; very low, smooth cephalic rim with a slight dorsal notch; with high pygidial keel. Anus dorsal, positioned just above the anal plaque. Tube unknown.
Remarks. Only one species in genus Notoproctus has been previously described from the area as Notoproctus oculatus antarcticus Arwidsson, 1911. Various reports of this species from the region suggest that more than one species could be present and possibly misidentified, particularly as this species is considered to occur from 218 – 5274m (Ehlers, 1913; Monro, 1939; Hartman, 1966,1967). Monro’s (1939) non-type material is housed at NHM collection and was re-examined. As already reported by Monro (1939) one specimen likely belongs to Nichomache. Others consistent with genus Notoproctus, but only one specimen is complete. This specimen is larger than Falkland Island specimens, eyes are absent, cephalic plaque has slight lateral notches, but has no dorsal notch.
Hartman (1966) states 18 chaetigerous and 2 pre-anal segments or 19 chaetigerous and 2 pre-anal segments and eyes absent. Hartman (1967) reported only 3 chaetigers with single spine, not 4. Ultimately, comparison with holotype of Arwidsson will be necessary, but given the lack of eyes in Falkland Islands specimens these will be assigned to morphospecies Notoproctus sp. 1 until further evidence is available.
