Chone orensanzi Tovar-Hernández, León-González & Bybee, 2017, sp. nov.

Chone orensanzi sp. nov.

( Figs 2, 3, 31 A)

Material examined. Type material: Holotype, UANL 8007; 38 paratypes, UANL 8008, ARGENTINA, Campaña SAO I, Golfo de San Matías, St. 23, 40°57’S, 65°05’W, 12.5 m depth, 17 February 1971, coll. J.M. Orensanz. Additional material: ARGENTINA, Campaña SANJO II, UANL 8009: Golfo de San José, off El Riacho, subtidal, 42°24’S, 64°35’W, May 1976, coll. J.M. Orensanz, 2 specimens in symbiosis with copepods; Campaña SAO I, UANL 8010, 40 °48’S (number station and longitude coordinates lost), 4 km off Las Grutas, 10 m depth, sand, 9 February 1971, 30 specimens; UANL 8011: St. 22, 40°54’S, 65°01’W, 16 m depth, gravel, 11 February 1971, coll. J.M. Orensanz, 50 specimens; UANL 8012: St. 24, 41°02’S, 65°08’30”W, 15 m depth, shell, 11 February 1971, coll. J.M. Orensanz, 4 specimens; UANL 8013: St. 26, 41°05’30”S, 65°08’30”W, 16.5 m depth, sand, 11 February 1971, coll. J.M. Orensanz, 10 specimens; UANL 8014: Golfo de San Matías, St. 3, 40°53’S, 64°43’W, 17.5 m depth, sand, 14 February 1971, coll. J.M. Orensanz, 1 specimen; UANL 8015: St. 5, 40°54’S, 64°31’W, 20–24 m depth, sand, 14 February 1971, coll. J.M. Orensanz, 4 specimens; UANL 8016: St. 15, 41°01’S, 64°15’W, 33–36 m depth sand & mud, 15 February 1971, coll. J.M. Orensanz, 1 specimen; UANL 8017: St. 53, 41°00’S, 65°06’W, 38 m depth, gravel & shell, 17 February 1971, coll. J.M. Orensanz, 2 specimens; UANL 8018: St. 54, 40°57’S, 65°03’W, 41.5 m depth, 17 February 1971, coll. J.M. Orensanz, 1 specimen. Campaña SAO II, UANL 8019: Golfo de San Matías, St. 54, 40°57’S, 65°03’W, 41.5 m depth, 17 February 1971, 2 specimens. Campaña SAO V, UANL 8020: Golfo de San Matías, St. 226, 40°53’S (longitude coordinates lost), 1 km off beach S of Bajo Oliveira, 20 m depth, 5 March 1973, coll. J.M. Orensanz, 1 specimen; UANL 8021: St. 228, 40°53’S (longitude coordinates lost), slightly S of Bajo Oliveira, 21 m depth, coarse sand & gravel, 5 March 1973, coll. J.M. Orensanz, 1 specimen; UANL 8022: St. 236, 40°53’S (longitude coordinates lost), off El Buque, 20 m depth, shell, 6 March 1973, coll. J.M. Orensanz, 1 specimen; UANL 8023: St. 240, 40°53’S, 64°55’W, between Bancos Paliza and Lobos, 18 m depth, 6 March 1973, coll. J.M. Orensanz, 6 specimens; UANL 8024: St. B, 40°47’S, 64°53’W, depth missing, N of Punta Villarino, at anchor (no date), coll. J.M. Orensanz, 5 specimens. Campaña COMP II, UANL 8025: Santa Clara del Mar, St. 7, 37°50’S, 57°24’W, 2 August 1963, 72.19 m depth, medium-fine sand, 108 specimens. Campaña COMP V, UANL 8026: St. 72, 38°18’S, 57°45’W, 25 m depth, medium sand, 27 May 1964, 3 specimens; UANL 8027: inner shelf off Mar del Plata, St. 81, 37°42’S, 57°17’W, 28 May 1964, 19 m depth, fine, medium & coarse sand, 2 specimens. Campaña Almirante Saldanha, UANL 8028: St. 2262a, 36°24’S, 55°00’W, 47 m depth, 9 November 1969, 1 specimen; UANL 8029: St. 2287a, 38°05’S, 56°43.5’W, 67 m depth, 16 November 1969, 2 specimens; UANL 8030: Isla Jabalí, Bahía San Blas, 40°34’ 50”S, 62°10’ 35”W, intertidal, April 1970, coll. J.M. Orensanz, A. Escofet & M.C. Estivariz, 3 specimens; UANL 8031, Bahía San Blas, 40°33’S, 62°14’W, March 1970, intertidal, 5 specimens. Campaña MEJILLON I, UANL 8032: Provincia de Buenos Aires, St. 11, 37°30’S, 56°33’W, 47 m depth, mud, 10 November 1971, 1 specimen; UANL 8033: St. 13, 37°20’S, 56°22’W, 47 m depth, mud, 10 November 1971, 1 specimen; UANL 8034: St. 15 bis, 37°10’S, 56°15’W, 28 m depth, sand, 10 November 1971, 2 specimens; UANL 8035: St. 18, 37°16’S, 56°06’W, 48 m depth, mud, 11 November 1971, 1 specimen; UANL 8036: Golfo San Matías, Las Grutas, 40°48’S, 65°05’W, intertidal, sheltered sandy beach, February 1972, 1 specimen. URUGUAY, Campaña Akademik Knipovich, UANL 8037: St. 250, 34°51’S, 52°35’W, 83 m depth, 1965, coll. V.N. Semenova & V. Scarabino, 20 specimens; UANL 8038: St. 1059, 35°25.9’S, 53°27.9’W, 80– 72 m depth, 1967, coll. V.N. Semenova & V. Scarabino, 1 specimen; UANL 8039: St. 1068, 34°15’S, 52°12’W, 55–62 m depth, 1967, coll. V.N. Semenova & V. Scarabino, 1 specimen; UANL 8040: St. 1071, 34°22.9’S, 52°37.2’W, 36– 42 m depth, 1967, coll. V.N. Semenova & V. Scarabino, 2 specimens.

Description. Trunk length 23 mm (4.7– 17 mm), width 2.3 mm (0.5– 2 mm). Branchial crown length 9 mm (2– 8 mm), with 15 pairs of radioles (8–16 pairs) (Fig. 2 B). Eight thoracic and 42 (36–39) abdominal segments. Attachment of branchial crown not exposed beyond collar. Palmate membrane extending for about 3/4 length of branchial crown (Fig. 3 A). Lateral flanges broad (Fig. 3 A). Radiolar tips long, filiform (space of 20 pinnules) (Fig. 3 B). Dorsal lips broadly rounded basally with a straight, radiolar appendage (Fig. 3 D). Ventral lips rounded, small. Three to four pairs of ventral radiolar appendages of different lengths, all shorter than branchial crown length (Fig. 3 D); 3 basal pinnules from dorsal most radioles long and fused by membrane. Ventral anterior peristomial ring lobe exposed beyond collar, distally entire, triangular. Antero-dorsal, ventral and lateral collar margins entire, ventral margin higher than dorsal (Fig. 2 C). Entire lengths of mid-dorsal collar margins form narrow gap (Fig. 2 D). Dorsal pockets well developed. Ventral shield of chaetiger 1 horseshoe-shaped, swollen (Fig. 2 E). Ratio of posterior peristomial ring collar length versus chaetiger 2 length, in lateral view: 1.5:1 (Fig. 2 C). Trunk cylindrical (Fig. 2 A). Thoracic chaetigers 2 to 8: Notopodia: superior group with two irregular rows of elongate narrowly hooded chaetae; inferior group with one anterior row of bayonet chaetae; two posterior rows with paleate chaetae with short mucros (Fig. 3 E). Neuropodia: acicular uncini handles as long as 10 times length of main fang (Fig. 3 F), distributed as regular row, dentition covering half length of main fang (Fig. 3 G), hood present. Glandular ridge on chaetiger 2 narrow all around (Fig. 2 C–E). Anterior abdominal segments: two transverse rows of elongate, narrowly hooded neurochaetae, upper row chaetae half as long as lower row ones; uncini (notochaeta) with dentition occupying half of main fang length, main fang not extending beyond breast. Posterior segments slightly depressed dorsoventrally containing: very elongate, narrowly hooded neurochaetae, 25% longer than those of anterior segments; uncini (notochaeta) rasp-shaped plates with square breast (Fig. 3 H). Pygidium triangular (Fig. 2 F), without cirrus.

Methyl green staining. Epidermis is completely glandular and stains uniformly in thorax and abdomen, dorsally and ventrally, except for anterior collar margin (Fig. 2 C–E). Anterior end of first ventral glandular shield does not take up stain, lateral sides of collar ventral shield dark (Fig. 2 C).

Type locality. Golfo de San Matías, Argentina, 40°57’S, 65°05’W.

Etymology. This species is dedicated to José María ‘Lobo’ Orensanz in recognition of his many publications on polychaetes, his remarkable contribution to fisheries, and for his interest and encouragement of those studying the Sabellidae from South America.

Remarks. As stated above only three species of Chone have been described from South America: C. insularis from Ilha Grande, Brazil, by Nonato (1981), and C. rosea and C. striata, which were both described from off South Chile by Hartmann-Schröder (1965). Chone orensanzi sp. nov., differs from C. insularis and C. striata by having a collar segment as long as 1.5 thoracic segments whereas in C. insularis and C. striata it is as long as three thoracic segments. In C. orensanzi sp. nov., the anterior margin of the peristomial ring lobe is exposed beyond the collar margin whereas in C. rosea and C. striata it is covered by the collar. Chone rosea has the ventral shield of chaetiger 1 sun glasses-shaped (horseshoe-shaped in C. orensanzi sp. nov., and C. striata) and extra-long radiolar tips (as opposed to long in C. orensanzi sp. nov., and short in C. striata) (Table 1).

Chone mollis (Bush in Moore, 1904), a species distributed from California, Western Mexico and Panama, has the anterior peristomial ring lobe exposed beyond the collar, distally entire, and triangular, similar to C. orensanzi sp. nov. However, in C. mollis paleate chaetae have a minute mucro (hair-like), not easily discernible, whereas in C. orensanzi sp. nov., it is well developed and easily seen. In addition, the handles of thoracic uncini in C. orensanzi sp. nov., are extremely long (more than 10 times length of main fang) versus 7 times the length of the main fang in C. mollis.

Augener (1931) reported C. infundibuliformis Krøyer, 1856, from between the Rio Grande and the mouth of La Plata River, but figures and diagnostic features were not included to confirm that his specimens belong in fact to C. infundibuliformis, which is an Arctic-Boreal species. Based on the redescription of C. infundibuliformis by Tovar-Hernández & Sosa-Rodríguez (2006), it is different from C. orensanzi sp. nov., by having short radiolar tips (long in C. orensanzi sp. nov.) and an anterior peristomial ring lobe that is not exposed beyond the collar (exposed in C. orensanzi sp. nov.).

Elías et al. (2001) reported Chone sp. cf. C. duneri from Mar del Plata, on shore, subtidal (ecological survey). Chone duneri Malmgren, 1867, is restricted to the Arctic Seas and North Atlantic Ocean (Tovar-Hernández et al. 2007), and it is easily distinguished from C. orensanzi sp. nov., by the presence of a bifid anterior peristomial ring lobe (entire in C. orensanzi sp. nov.).

Chone orensanzi sp. nov., is unique among Chone species in having a set of distinguishable features: 1) the anterior peristomial ring lobe is triangular, exposed beyond the collar, 2) a short collar (as long as 1.5 times the length of chaetiger 2), 3) ventral shield of chaetiger 1 horse-shoe shaped, 4) radiolar flanges broad, 5) radiolar tips long, filiform and 6) thoracic uncini as long as 10 times the lengths of main fangs. In addition, branchial crowns of two large specimens (body lengths 12–17 mm; branchial crown lengths 4.5– 8 mm) from lot UANL 8009 were found infested with copepods (Fig. 3 C) but the identity of these parasites remains unknown. Members of three families of copepods are typically external parasites of sabellids: Gastrodelphyidae, Sabelliphilidae and Rhynchomolgidae. Many species of these copepod families have been reported on sabellids of the genera Eudistylia, Acromegalomma, Parasabella, Pseudopotamilla, Bispira, Myxicola, Potamilla, Perkinsiana and Sabella (Capa et al. 2014 and references therein), but none on members of Chone.

Remarks. Jasmineira is composed of 17 species (Fitzhugh 2002; Capa & Murray 2015). None of these was described from South America but four species have been described from Antarctica: J. crumenifera Hartmann- Schröder, 1986, from South Shetlands, 488 m depth; J. caeca Ehlers, 1913, and J. macrophthalma Ehlers, 1913, both from Kerguelen Islands (Observatory Bai), and J. regularis Hartman, 1978, from the Weddell Sea, 512–2936 m depth. In this study, we report J. crumenifera from the Uruguayan shelf.