Paucibranchia disjuncta

Description. Specimens with L 10 = 1.2 – 6.4 mm, W 10 = 0.3 – 4 mm. Prostomium entire. Median antenna reaching from first peristomial ring to third chaetiger; lateral antennae reaching from second peristomial ring to the middle of second chaetiger; palps reaching from the middle of first peristomial ring to middle of the first chaetiger. Palpostyles and ceratostyles without peduncle. Eyes present. Maxillary formula: MII 5 – 7 + 6 – 7, MIII 6 – 8, MIV 3 – 5 + 6 – 9. Length of MI from 0.4 mm to 2 mm, maxillary carrier length from 0.25 mm to 0.9 mm, closing system length from 0.1 to 1 mm, MII length from 0.3 mm to 0.9 mm, opening cavity length from 0.1 mm to 1 mm. Pectinate branchiae starting from chaetigers 6 – 15 to chaetigers 9 – 33. The maximum number of branchial filaments from 4 to 26. Dorsal cirri conical in anterior chaetigers, filiform in following ones, in median-posterior region 2.7 times longer than pre-branchial chaetigers. Prechaetal lobe as a transverse fold in all chaetigers. Chaetal lobe rectangular in anterior region, triangular in media-posterior parapodia. Postchaetal lobe conical and well-developed in first 7 – 74 chaetigers; thinner and elongated in branchial chaetigers; inconspicuous in median-posterior chaetigers. Ventral cirri conical in the first chaetigers and posterior chaetigers; with a small swollen base from chaetigers 1 – 6 to chaetigers 9 – 71. Aciculae blunt, reddish at the base and distally amber in all parapodia. Limbate chaetae of two sizes in same chaetiger. Two types of pectinate chaetae: (1) in anterior chaetigers, 1 – 2 pectinate isodont narrow chaetae with 5 – 6 long and slender teeth, with oblique distal edge; (2) in median-posterior chaetigers, 2 – 4 pectinate isodont narrow chaetae with 10 – 11 short and slender teeth, with oblique distal edge. Compound spinigers present in first 7 – 26 chaetigers (specimens with L 10 ≤ 2 mm), or present in all chaetigers in specimens with L 10> 2 mm. Compound falcigers in each parapodium present in juveniles and short specimens, with blades of one length; in adults, with falcigers only in median or posterior region. Subacicular hooks with reddish basal end, starting in chaetigers 9 – 39, with up to one or two hooks per chaetiger; in specimens with L 10 ≤ 2.5 mm hooks bidentate; in specimens with L 10 = 2.6 – 3.8 mm hooks bidentate in anterior regions, but unidentate in median-posterior ones; in specimens with L 10> 3.8 mm hooks unidentate.

Remarks. See Molina-Acevedo (2018) for redescription of P. disjuncta and additional details about the morphology and development of this species.

Distribution. Southern California, USA.

Type material examined. Holotype (LACM-AHF POLY 724) 1 adult specimen, 2.2 miles ESE (bearing 114 ° T) from Los Angeles Light, Los Angeles County, California, USA, North Pacific, 33 ° 41 ’ 36 ’’ N 118 ° 12 ’ 37 ’’ W, R / V VELERO IV sta. 2107 – 52, in sand and mud, Hayward orange peel grab, 23. 77 m, 20 April 1952. Additional material examined. (LACM-AHF POLY 6953) 1 juvenile, off Palos Verdes, Los Angeles County, California, USA, 33.73320 ° N 118.40050 ° W, R / V OCEAN SENTINEL sta. 0106 – 3 D, 30 m, 10 January 2006, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACMAHF POLY 10195) 4 adult, 6.7 miles from Ventura Pier Light bearing 270 ° true north, Ventura, Ventura County, Southern California Bight, California, USA, 34 ° 16 ’ 15 ’’ N 119 ° 25 ’ 40 ’’ W, R / V VELERO IV sta. 5594 – 58, green mud, grab, 22 m, 30 January 1958, coll. Allan Hancock Foundation. (LACM-AHF POLY 6946) 5 adults, 1.8 miles bearing 062 ° true north from Point Fermin Light, Los Angeles County, California, USA, 33 ° 43 ’ 05 ’’ N 118 ° 15 ’ 43 ’’ W, R / V VELERO IV Sta. 6107 – 59, black silt, Hayward orange peel grab, 13 m, 19 February 1959, coll. Allan Hancock Foundation. (LACM-AHF POLY 6955) 1 adult, Los Angeles County, California, USA, 33.81170 ° N 118.44170 ° W, R / V OCEAN SENTINEL sta. 0191 – 0 B, 152 m, 16 January 1991, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6956) 1 specimen, off Palos Verdes, Los Angeles County, California, USA, 33.75730 ° N 118.44100 ° W, R / V OCEAN SENTINEL sta. 0191 – 1 C, 61 m, 16 January 1991, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6957) 1 adult, off Palos Verdes, Los Angeles County, California, USA, 33.73770 ° N 118.42320 ° W, R / V OCEAN SENTINEL sta. 0192 – 2 C, 61 m, 22 January 1992, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6958) 1 adult, off Palos Verdes, Los Angeles County, California, USA, 33.66850 ° N 118.29680 ° W, R / V OCEAN SENTINEL sta. 0193 – 10 C, 61 m, 14 January 1993, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6960) 1 adult, 33.80720 ° N 118.43050 ° W, R / V OCEAN SENTINEL sta. 0196 – 0 C, 61 m, 24 January 1996, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6961) 1 adult, off Palos Verdes, Los Angeles County, California, USA, 33.73000 ° N 118.40250 ° W, R / V OCEAN SENTINEL sta. 0197 – 3 C, 61 m, 15 January 1997, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM - AHF POLY 6964) 2 adults, off Palos Verdes, Los Angeles County, California, USA, 33.80720 ° N 118.43050 ° W, R / V OCEAN SENTINEL sta. 0702 – 0 C 2, 61 m, 17 July 2002, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6965) 2 adults, off Palos Verdes, Los Angeles County, California, USA, 33.80720 ° N 118.43050 ° W, R / V OCEAN SENTINEL sta. 0790 – 0 C 1, 61 m, 18 July 1990, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6967) 2 adults, off Palos Verdes, Los Angeles County, California, USA, 33.80720 ° N 118.43050 ° W, R / V OCEAN SENTINEL sta. 0793 – 0 C 1, 61 m, 14 July 1993, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6968) 1 adult, off Palos Verdes, Los Angeles County, California, USA, 33.80720 ° N 118.43050 ° W, R / V OCEAN SENTINEL sta. 0794 – 0 C, 61 m, 21 July 1994, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6969) 2 adults, off Palos Verdes, Los Angeles County, California, USA, 33.80720 ° N 118.43050 ° W, R / V OCEAN SENTINEL sta. 0795 – 0 C 1, 61 m, 14 July 1995, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6970) 1 adult, off Palos Verdes, Los Angeles County, California, USA, 33.80720 ° N 118.43050 ° W, R / V OCEAN SENTINEL sta. 0796 – 0 C 1, 61 m, 11 July 1996, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6972) 1 adult, off Palos Verdes, Los Angeles County, California, USA, 33.73320 ° N 118.40050 ° W, R / V OCEAN SENTINEL sta. 0798 – 3 D, 30 m, 15 July 1998, coll. Los Angeles County Sanitation District, Marine Biology Laboratory. (LACM-AHF POLY 6974) 1 adult, off Palos Verdes, Los Angeles County, California, USA, R / V OCEAN SENTINEL sta. W 30, 10 November 1997, coll. Los Angeles County Sanitation District, Marine Biology Laboratory.