Fabrisabella vasculosa Hartman, 1969

Tovar-Hernández, María Ana, León-González, Jesús Angel De & Hendrickx, Michel E., 2025, Polychaeta collected during the research cruises TALUD aboard the R / V “ El Puma ” in the Mexican Pacific: Sabellidae and Serpulidae, Zootaxa 5663 (1), pp. 1-80 : 35-37

Fabrisabella vasculosa Hartman, 1969

( Fig. 18 )

Fabrisabella vasculosa Hartman, 1969: 699 , figs 1–4.— Fitzhugh, 1989: 70.

Material examined. ICML-EMU-14030: TALUD XV, St. 20, BS, 26º30'42"N 113º56'0"W, 01 August 2012, 540– 568 m, 1 specimen without abdomen. ICML-EMU-14031: TALUD XV, St. 23, BC, 27º08'11"N 114º32'54"W, 01 August 2012, 681 m, 1 specimen without posterior thorax and abdomen .

Description of material examined. Thorax 1.5 mm wide. Branchial crown 4–4.2 mm long with 12 pairs of radioles. Thorax with eight chaetigers. Abdominal chaetigers unknown (incomplete specimens). Radioles fused basally by reduced palmate membrane. Radioles with narrow flanges along the entire length. Radiolar tips short, filiform, occupying space of 4–5 pinnules width. Radiolar eyes absent. Dorsal lips low, curved slightly at the same angle as the radiolar lobes, without mid-radiolar appendage ( Fig. 18B ). Ventral lips small, rounded. Parallel lamellae absent. Ventral radiolar appendages present, 3–5 pairs, small, not longer than collar segment length ( Fig. 18B ).Ventral margin of collar with a narrow median-incision, forming two discrete rounded lappets ( Fig. 18C ) with brownish spots at their base ( Fig. 18C ). Lateral collar margin entire, diagonal, exposing partially the anterior peristomial ring ( Fig. 18E ). Mid-dorsal collar margins fused to faecal groove, dorsal margin continues in U-shaped pockets, exposing in full two pairs of distinct brown vascular coils ( Fig. 18D ). Anterior pair of coils larger than posterior pair ( Fig. 18D ). Glandular ridge on chaetiger 2 present, narrow and whitish dorsally ( Fig. 18A ), ventrally vestigial. Thoracic shields well developed, rectangular with well defined lateral borders ( Fig. 18C ). Thoracic notochaetae with superior and inferior groups of chaetae. Superior thoracic notochaetae elongate narrowly hooded. Inferior thoracic notochaetae with 1–2 transversal rows of paleate chaetae. Bayonet chaetae absent. Thoracic uncini acicular, teeth above the main fang equal in size, extending 1/2 of the main fang length. Abdomen and pygidium unknown. Tubes not preserved. Specimen St. 23 a female with mature oocytes developing in thorax.

Remarks. Fabrisabella is composed of two species ( Capa et al. 2021). Fabrisabella vasculosa was described from 11.6 mi SW off Point Vicente lighthouse, Southern California, USA, to 731 m depth, and F. similis Fauchald, 1972 from 35 mi off Cabo Corrientes lighthouse, Jalisco, Mexico, to 2,650 m depth. In the present study, F. vasculosa is reported for the first time in Mexican waters. The material examined fits well with original description by Hartman (1969). Since its establishment the species has not been reported or illustrate, except for the re-examination of the holotype by Fitzhugh (1989).

In F. vasculosa there are two pairs of vascular coils whereas in F. similis there is only one pair. In both species the ventral margin of collar is incised, but in F. vasculosa the lappets are shallow, rounded, whereas these are high, triangular in F. similis . The two specimens examined present entire crowns (no abscission zone/breaking plane at the base of branchial crown) but none of these preserve the abdomen in order to corroborate chaetal and uncinial features.

Abiotic conditions. The specimens of F. vasculosa were collected from 540‒681 m deep, under the following environmental conditions. Temperature : 6.44‒8.38°C; salinity: 34.45‒34.51; dissolved oxygen: 0.07‒0.15 ml O 2 /l; %MO: 5.15‒5.47; sediments dominated by sand and silt (sand: 46.6, 47.1%; silt: 46.2, 46.6%) ( Table 1). Distribution. West coast of Baja California Sur, Mexico .

Genus Jasmineira Langerhans, 1880

Figures

FIGURE 18. Fabrisabella vasculosa Hartman, 1969. A) Branchial crown and thorax, dorsal view, B) dorsal lip and ventral pinnular appendages from left radiolar lobe, C) first three thoracic chaetigers, ventral view, D) vascular coils, E) first three thoracic chaetigers, lateral view, right radiolar lobe removed.Abbreviations: dl—dorsal lip, gr2—glandular ridge on chaetiger 2, vsc—ventral shield of collar, vc—vascular coils, vpa—ventral pinnular appendages, 1, 2, 3—refer to the number of chaetigers. A–E) Stained with methyl green. Scale bars: A) 1 mm, B) 0.5 mm, C) 0.4 mm, D–E) 0.5 mm. A–E: ICML-EMU-14031.