Paucibranchia disjuncta ( Hartman, 1961 )

Molina-Acevedo, Isabel C., Fernández-Rodríguez, Vanessa & Idris, Izwandy, 2022, Morphometric approach to supports distinction among three species of Paucibranchia Molina-Acevedo, 2018 (Annelida: Eunicidae), Zootaxa 5155 (3), pp. 347-370 : 354-355

Paucibranchia disjuncta ( Hartman, 1961)

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. 0106–3D, 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. 0191–0B, 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. 0191–1C, 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. 0192–2C, 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. 0193–10C, 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. 0196–0C, 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. 0197–3C, 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. 0702–0C2, 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– 0C1, 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. 0793–0C1, 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. 0794–0C, 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. 0795–0C1, 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. 0796–0C1, 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. 0798–3D, 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. W30, 10 November 1997, coll. Los Angeles County Sanitation District, Marine Biology Laboratory.

Description. Specimens with L10= 1.2–6.4 mm, W10= 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 L10 ≤ 2 mm), or present in all chaetigers in specimens with L10> 2mm. 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 L10 ≤ 2.5 mm hooks bidentate; in specimens with L10= 2.6–3.8 mm hooks bidentate in anterior regions, but unidentate in median-posterior ones; in specimens with L10> 3.8 mm hooks unidentate.

Distribution. Southern California, USA.

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