Chaetozone PAP sp55

Family:

Cirratulidae

Genus:

Chaetozone

Species binomial name, or informal name:

Chaetozone PAP sp55

Authority:

Eulogio Soto & Gordon Paterson

Material Examined:

128 individuals examined. Porcupine Abyssal Plain (Discovery 185, August 1989 3 individuals; Challenger 79, May 1991 34 individuals; Challenger 111, April 1994 1 individuals; Discovery 222, September 1996 24 individuals; Discovery 226, March 1997 29 individuals; Discovery 229, July 1997 21 individuals; Discovery 231, March 1998 7 individuals and Discovery 237, September 1998 9 individuals).

Voucher: Ocean Basin:

NE Atlantic

Voucher: Cruise/Expedition:

BENGAL Programme

Voucher: Location:

48.00º N -16.00 º W

Voucher: Depth:

4835 m

Voucher: Repository:

NHM London

Description:

Body shape in lateral view: same shape throughout. Overall body shape in dorsal view: fusiform (cigarshaped). Thoracic body shape in dorsal view: expands in width to juction of thorax with abdomen. Thoracic profile in TS: ventrally flattened but dorsally rounded. Total number of chaetigers: less than 50 chaetigers. Pigmentation of body (in preservative): no obvious pigmentation. Parapodia shape: not obviously elevated. Methyl green pattern: Uniform.
Number of thoracic chaetigers: 20 chaetigers. Prostomium shape: conical with pointed/rounded tip. Lateral view of prostomium: prostomium pointed forward. Nuchal organ: not observed. Sub-dermal eyes: not present. Annulations on peristomial region: three annulations. Dorsal crest on prostomium (lateral view): absent. Dorsal ridge: absent. Position of the dorsal tentacles: on margin of peristomium and first chaetiger. First branchial position in dorsal view: first pair of branchiae situated distal to dorsal tentacles. Very long thoracic bottle-brush notochaetae: present. Bottle-brush chaetal length: 4 chaetigers long. Thoracic bottle-brush notochaetae starting at chaetiger 1–5 . Number of thoracic notochaetae per fascicle: 5–6 chaetae. Number of thoracic neurochaetae per fascicle: 4–6 chaetae. Thoracic neurochaetal type: all capillaries.
Intermediary body region between thorax and abdomen: present. Intermediary body region length: 2–3 chaetigers. Intermediary body region chaetae: bottle-brush’ chaetae present. Abdominal segment shape: consertina - constricted between segments. Groove on abdominal segments: grooves absent. Abdominal acicular spines: absent. TS shape of abdominal segments: rounded, circular. Abdominal ‘bottle-brush’ chaetae: absent. Description of modified chaetae: Simple chaetae aranged in dense cinctures. Pygidium: anus surrounded by lobes of similar size.
Habitat: Habitat: sediment dwelling.

Remarks:

This species mainly differs from Chaetozone sp.685 in prostomium length and shape, buccal region length, starting position and length of long chaetae (‘bottle-brush’), the absence of acicular spines in thoracic region and pygidium shape. The presence of eggs in intermediary body region (between thorax and abdomen) was observed in some specimens. One specimen has a blunt rounded prostomium but in all other regards has the features as the other specimens.

Illustrations:

Photographic plate 1. Chaetozone PAP sp55. Top left: anterior view showing rstomium and thoracic chaetigers. Top right: pygidium. Bottom left partial view of whole animal. Bottom right: whole specimen.
SEM plates. Chaetozone PAP sp 55. Clockwise from left: anterior view of worm. Prostomial and peristomial region, head showing insertion of dorsal tentacles. Detail of chaetae in anterior part of worm. Thoracic segments showing arrangement of noto and neurochaetae.