Parasabella yonowae, Tovar-Hernández, María Ana, León-González, Jesús Ángel De & Bybee, David R., 2017

Tovar-Hernández, María Ana, León-González, Jesús Ángel De & Bybee, David R., 2017, Sabellid worms from the Patagonian Shelf and Humboldt Current System (Annelida, Sabellidae): Phyllis Knight-Jones’ and José María Orensanz’s collections, Zootaxa 4283 (1), pp. 1-64 : 33

Parasabella yonowae sp. nov.

( Figs 15 , 16 , 32 C)

Material examined. Type material: ARGENTINA, Holotype ( UANL 8069 ), 3 paratypes ( UANL 8070 ), Campaña Sanjo II, Golfo de San José, off El Riacho, 42°24’S, 64°35’W, subtidal, May 1976, coll. J.M. Orensanz. Additional material : ARGENTINA, UANL 8071 : Campaña Sanjo II, Golfo de San José, off San Roman , 42°16’S, 64°14’W, 60.35 m depth, dredge haul 3, on cerianthid tubes, coll. J.M. Orensanz, 11 May 1976, 1 female with abdominal oocytes . UANL 8072–8073 : Puerto Deseado , Provincia de Santa Cruz, encrusting community, 6.5 m depth, 18 October 2005, coll. E. Schwindt, 5 specimens, and St. 1E, fouling communities on succession panels, 22 May 2007, coll. E. Schwindt, 2 specimens, respectively . URUGUAY, UANL 8074 : Campaña Akademik Knipovich , St. 1055, 36°16’S, 54°01.5’W, 92–96 m depth, 1967, 1 specimen .

Description. Trunk length 58 mm (16–20 mm), width 5 mm (2–3.5 mm). Branchial crown 17 mm length (9 – 10 mm), with 27 pairs of radioles (13 – 16 pairs). Eight thoracic and 112 abdominal segments (44 – 64). Palmate membrane and radiolar eyes absent ( Fig. 16 A). Radioles with narrow flanges basally ( Fig. 16 B), then very broad including radiolar tips ( Fig. 16 C, D). Longest pinnules at mid-radiole length. Radioles with very long, digitiform tips, flattened, as long as equivalent space of 30 pinnules ( Fig. 16 C). Dorsal lips triangular ( Fig. 15 F), as long as chaetiger 1 in ventral side, erect, with distinct radiolar appendages and adjacent lateral lamellae and one dorsal pinnular appendage. Ventral lips broadly rounded with two ventral pinnular appendages. Parallel lamellae present, sometimes exposed, in between ventral lappets on ventral incision of collar ( Fig. 15 D, F). Mid-dorsal collar margins not fused to faecal groove, exposing anterior peristomial ring ( Fig. 15 A, B). Faecal groove wide and depth in thorax ( Fig. 15 A, B). Ventral lappets of collar short with rounded distal margins ( Figure 15 D, E), not overlapping ( Fig. 15 D), or slightly overlapping ( Fig. 15 E). Lateral collar margins even, covering basal union of radioles ( Fig. 15 C). Ventral shield of chaetiger 1 swollen, rectangular, with concave anterior margin and convex lateral margins, 1.5 times longer than length of chaetiger 2 shield ( Fig. 15 D, E), sometimes with shallow longitudinal and transverse divisions. Chaetiger 1 with elongate narrowly hooded chaetae. Thoracic ventral shields trapezoidal ( Fig. 15 D, E). Chaetiger 2 slightly shorter than others, not contacting ventral shield, 3–8 thoracic neuropodial tori in contact with shields ( Fig. 15 E). Superior thoracic notochaetae narrowly hooded, two times longer than inferior group, hood 1/8 width of shaft. Inferior thoracic notochaetae narrowly hooded (Type B), hood 1/4 width of shaft ( Fig. 16 E, F). Thoracic uncini with nine rows of teeth of equal size above main fang, occupying one-half length of main fang, hood absent, breast well developed, handles two times longer than main fang (medium size) ( Fig. 16 H). Companion chaetae with denticulate bulbous head with one longer tooth, and elongate membranous tip ( Fig. 16 I). Abdominal chaetae with two rows of elongate, with very narrow hoods, all chaetae equal in size ( Fig. 16 G). Abdominal uncini dentition similar to thorax but with short handles, two times as long as main fang and 7 – 8 rows of teeth. Pygidium rounded; two groups of reddish-brownish pygidial eyes of unequal size. Tubes unknown.

Type locality. Golfo de San José, off El Riacho, 42°24’S, 64°35’W, subtidal.

Etymology. The species is named after Dr. Nathalie Yonow, an expert on nudibranchs, in recognition of her kind support for the shipment of Phyllis Knight-Jones and Jose María ‘Lobo’ Orensanz’s sabellid collections to Mexico. Through her kind support, these collections have been very useful for the study of South American sabellids.

Remarks. Parasabella columbi and P. yonowae sp. nov., were found in the Golfo de San José. The major differences between P. yonowae sp. nov., and P. columbi are the following: 1) In P. yonowae sp. nov., the ventral shield of chaetiger 1 is 1.5 times longer than the length of chaetiger 2 shield (twice as long as the length of the shield in P. columbi ); 2) the ventral lappets of collar are triangular and long in P. columbi (distally rounded, short in P. yonowae sp. nov.); 3) the radiolar tips are very long in P. yonowae sp. nov., as long as equivalent space of 30 pinnules (short in P. columbi , equivalent to 8–9 pinnules); 4) flanges are narrow along radioles in P. columbi (narrow at the radiolar bases, then broad towards radiolar tips in P. yonowae sp. nov.); 5) P. yonowae sp. nov., has pygidial eyes (absent in P. columbi ) ( Table 2).

Parasabella yonowae sp. nov., have very long radiolar tips versus short tips in P. columbi and P. leucaspis complex. Radiolar tips have wide flanges in P. yonowae sp. nov., and P. fernandezensis , however in the latter species the tips are lanceolate, leaf-like, whereas in P. yonowae sp. nov., flanges are even. The ventral lappets are short in P. yonowae sp. nov., and P. leucaspis complex whereas in P. columbi these are long ( Table 2).

Figures

FIGURE 15. Parasabella yonowae sp. nov. A, B) Collar and anterior thoracic segments, dorsal view, C) same, lateral view, D, E) same, ventral view, F) dorsal lip, radioles, and parallel lamellae. Arrows in D and F point to parallel lamellae. Scale bars: A, B, D 2.5 mm, C, E 1 mm, E 1 mm, F 2 mm. Abbreviations: dl dorsal lip, vsc ventral shield of chaetiger 1. Stain: A – E methyl green. Specimens: A, D, F holotype, UANL 8069, B, C, E paratype, UANL 8070.

FIGURE 16. Parasabella yonowae sp. nov. A) Base of branchial crown, B) mid-radiolar region, C) radiolar tip and flanges, D) detail of radiolar flange, E) thoracic notochaetae, F) inferior, narrowly hooded thoracic notochaetae, G) abdominal neurochaetae, H) thoracic uncini, I) companion chaetae. Arrows in B – D point to radiolar flanges. Scale bars: A 1 mm, B 0.4 mm, C, D 0. 1 mm, E – G 100 µm, H, I 10 µm. Specimen: A – I holotype, UANL 8069.

FIGURE 32. Distribution of some sabellid species in South America. A) Myxicola sulcata Ehlers, 1912, B) Notaulax tilosaula (Schmarda, 1861) (star) and Notaulax salazari sp. nov. (circle), C) Parasabella columbi (Kinberg, 1867) (circles) and Parasabella yonowae sp. nov. (star denotes type locality and triangle indicates additional records).