Levinsenia barwicki Lovell & Fitzhugh 2020, n. sp.

Levinsenia barwicki n. sp.

Figures 6 A–F, 7G

Levinsenia sp SD1 Barwick 2000§ Levinsenia sp A Phillips (unpublished)

Material examined. USA, California. Santa Barbara County, Gaviota, GAVBIOCORE, 28 October 1993, Sta. C, rep. 1, ~ 34°27’29”N, 120°12’43”W, 27 m depth, 0.008m ² hand core, 0.5 mm sieve, holotype (LACM-AHF 12590). Western Santa Barbara Channel, Chevron Platform Gail, Sta. 6, rep. 1, ~ 34.28°N, 119.59°W, March 1984, 0.1 m ² Smith-McIntyre grab, 1.0 mm sieve, 1 paratype (LACM-AHF 12591).— San Diego County, City of San Diego Regional Survey 2010, Sta. 8032, 32.56°N, 117.19°W, 6 July 2010, 33 m depth, 0.1 m ² Van Veen grab, 1.0 mm sieve, 1 paratype (USNM 1548300); South San Diego Shelf, City of San Diego, SCCWRP Bight 2013, Sta. 9007, 15 July 2013, 35 m depth, 32.5515°N, 117.1995°W, 0.1 m ² Van Veen grab, 1.0 mm sieve, 1 paratype (LACM-AHF 12593).— Los Angeles County, Outer Los Angeles Harbor, Catalina Sea Ranch, Sta. 1, 22 February 2016, 45 m depth, 33.61260°N, 118.10437°W, 0.1m ² Van Veen grab, 1.0 mm sieve, R / V Yellowfin, 1 paratype (LACM-AHF 12596).

Additional material. USA, California. Santa Barbara County, Gaviota, GAVBIOCORE Sta. Ni, rep. 1, ~ 34°27’29”N, 120°12’43”W, 27 m depth, 13 August 1992, 0.008 m ² hand core, 0.5 mm sieve, id. L. Lovell, 1 specimen mounted on SEM stub (LACM-AHF 12597); Monterey County, Monterey Bay, MBARI sample T387 C76, 36.20°N, 122.62°W, 5 December 2001, 3322 m depth, 6.9 cm diameter tube core, top 5 cm, 0.3 mm sieve, ROV Tiburon, 1 specimen (LACM-AHF 12594); Monterey Bay, MBARI sample T387 C80, 36.20°N, 122.62°W, 5 December 2001, 3322 m depth, 6.9 cm diameter tube core, top 5 cm, 0.3 mm sieve, ROV Tiburon, 1 specimen (LACM- AHF 12595); Monterey Bay, MBARI MARS sample D703-PC45, 36.71°N, 122.19°W, 17 December 2014, 889 m depth, 6.9 cm diameter tube core, top 5 cm, 0.3 mm sieve, ROV Doc Ricketts, determined by T. Phillips, 2 specimens ( USNM 1604268); MBARI MARS sample D702-PC49, 36.75°N, 122.28°W, 17 December 2014, 1001 m depth, 6.9 cm diameter tube core, top 5 cm, 0.3 mm sieve, ROV Doc Ricketts, id. T. Phillips, specimen labelled as Levinsenia sp SD1, 1 specimen mounted on SEM stub (LACM-AHF 12598); labelled as SD1; Monterey Bay, MBARI sample T387 C57, 36.20°N, 122.62°W, 5 December 2001, 3322 m depth, 6.9 cm diameter tube core, top 5 cm, 0.3 mm sieve, ROV Tiburon, 1 specimen; Southern California Bight, South of Imperial Beach, City of San Diego South Plant Ocean Outfall, I15 rep. 1, 32.54°N, 117.19°W, 6 July 2015, 33 m depth, Van Veen grab, 1.0 mm sieve; City of San Diego South Plant Ocean Outfall, Sta. I16, rep. 1, 32.54°N, 117.18°W, 13 July 2006, 28 m depth, 0.1 m ² Van Veen grab, 1.0 mm sieve.

Description. Holotype 4 mm long, 0.10 mm wide, complete, damaged mid-body. Body slightly inflated in prebranchial region, thereafter cylindrical in cross section. Body cream colored. Prostomium conical; terminal sensory organ well developed, mid-prostomial ciliary recessed area (Fig. 6A); peristomial ciliated nuchal organs; lateral ciliary patches, dorsal and ventral ciliary patches (Fig. 6B); median antenna absent. Six prebranchial segments, followed by 5 (6 th developing on one side) pairs of heavily ciliated, truncate, leaf-like, branchiae (Fig. 6C), mid-dorsal transverse ciliary bands continuous with branchiae (Fig. 6D). Notopodial glandular pores absent. Post-branchial neurochaetae acicular, up to 5 acicular spines with sharply bent tip and thick surrounding sheath (Fig. 6E), alternating with capillary chaetae. Far posterior chaetigers with pad-like chaetal fascicles, capillary notochaetae extremely long. Anal cirri distally inflated with cilia at tips (Fig. 6F).

Methyl green stain. Staining limited to pre-chaetal areas of notopodia in branchial and 7–8 post-branchial chaetigers (Fig. 7G).

Type locality. USA, Santa Barbara County, Gaviota, California, 27 m depth.

Distribution. Central to southern California, 27–3322 m depth.

Variations. Paratypes: body up to 15 mm long. Branchiae up to 8 pairs, heavily ciliated.

Remarks. Levinsenia barwicki n. sp. is distinct by way of the several patches of cilia on the prostomium, especially on the mid-prostomial recessed area where a median antenna is found in other Paraonidae. Lateral ‘cheek’ and ventral ciliary patches are noted and have not been previously described. Branchiae are heavily ciliated, flattened and leaf-like, similar to Paraonis pygoenigmatica (Jones, 1968) (formerly Levinsenia pygoenigmatica, reassigned to Paraonis, see Blake 2016). Neurochaetae are unidentate, sharply bent, with a thick sheath, ‘appearing’ bidentate using light microscopy; unlike L. canariensis and L. hawaiianensis, which are truly bidentate. J. Blake (pers. comm.) reports that other very small, shelf and slope Levinsenia with similar branchial and neurochaetal features are known to exist in the North Atlantic. Levinsenia barwicki is a very small species and is usually collected on a 0.5 mm (or finer) sieve, occasionally on a 1.0 mm sieve.

The reported depth range for L. barwicki is very broad. However, other Levinsenia species present such broad depth ranges. Blake (1996) reports Levinsenia gracilis occurring from “shallow subtidal to 3000+ m”. This species is named in honor of Kelvin Barwick, SCAMIT President.