Chone johnstonae, Tovar-Hernández, María Ana, 2005

Tovar-Hernández, María Ana, 2005, Redescription of Chone americana Day, 1973 (Polychaeta: Sabellidae) and description of five new species from the Grand Caribbean Region, Zootaxa 1070, pp. 1-30 : 18-21

Chone johnstonae sp. nov.

Figures 8 A–I, 9A–N

Material examined

Type material: Holotype [ FSBC I 66736], Paratype [ FSBC I 66737] (1): Turpialito, Cumaná, Venezuela, Coll. M. Liñero, February 22, 2002, 4 m.

Non­type material: Venezuela: [ECOSUR] Los Testigos, Isla Margarita, 20 m, June 10, 1961 (1). Golfo de Santa Fe, Coll. O. Díaz, June 19, 2004 (2). Ensenada de José, Coll. O. Díaz, July 20, 1997 (1).

Additional material: Chone letterstedti ( Kinberg, 1867) . Holotype [ SMNH 576] Cape of Good Hope, South Africa.

Description (inside parentheses variation observed in paratype and non­type material, respectively)

Color, body shape and size: Body pale in preserved material; cylindrical in thorax and anterior part of abdomen ( Figure 9 A); depressed in posterior part of abdomen; BoL= 10 mm (8.5–20), W= 1.5 mm (2).

Branchial crown: BrCL= 3.7 mm (8), RML/BrCL= 0.75/1. Radioles: 11 (13) pairs, narrow flanges ( Figures 8 E, I), pinnules long, of similar length throughout radiole, RT= medium­sized [9 pinnules] ( Figures 8 E, I). Radiolar skeleton composed of 2 rows of cells ( Figure 8 H), continued into pinnules. BrL= small, insertion not exposed beyond collar ( Figures 8 A–C). DL= 3 times longer than wide, without a discernable longitudinal ridge ( Figures 8 F–G). VL= rounded, as long as wide, about one half of the DL length. VRA= 4 pairs, the inner one about one quarter of the BrCL, medium about one half of the BrCL, the distal one about the same length of the BrCL, the remainder about one half of the BrCL ( Figure 8 F). Lateral radioles are parasitised by an unidentified copepod ( Figure 8 H).

Peristomium : APRL= not exposed beyond collar, ventral margin distally entire, triangular. PPRC= antero­dorsal, lateral and ventral collar margins entire, slightly high ventrally ( Figures 8 A–C). VSC= swollen, horseshoe­shaped, 2 times wider than long ( Figure 8 A). PPRCL/ Ch 1L= 1/1.

Thorax: Chaetiger 1= Notopodia: two groups of 5 elongate, narrowly hooded chaetae. Chaetigers 2 to 8= Notopodia: SG= 5 elongate, narrowly hooded chaetae ( Figure 9 A), IG= 1 anterior row with 6 short bayonet chaetae ( Figures 9 A, F), 2 posterior rows with 6–7 symmetrical, paleate chaetae with short mucro ( Figures 9 A, B–E). Neuropodia: 1 row of 10­14 acicular uncini per torus, MF= 4, covering three quarters of the MF length, teeth above MF unequal in size, basal tooth bigger than teeth in distal rows, hood present, handles long ( Figures 9 G–H). GR2= narrow, of same width around the segment.

Abdomen: AS = 29. Anterior segments: 2 transverse rows of 8–9 elongate, narrowly hooded chaetae ( Figures 9 I–J), chaetae from the upper row 50% shorter than chaetae in lower row; 13–16 uncini per torus ( Figure 9 L), MF= 2–3, covering one half of the MF length, teeth above MF equal in size, breast rectangular, well developed, main fang not extending beyond breast, handles absent ( Figure 9 M). Posterior segments: 5 modified, elongate, narrowly hooded chaetae ( Figure 9 K); 4–6 modified uncini per torus, MF= 7–8, covering three quarters of the MF length, teeth above MF equal in size, breast rectangular, poorly developed, main fang not extending beyond breast, handles absent ( Figure 9 N). Pygidium subtriangular, without cirrus ( Figure 8 D).

Gametes: Paratype female with oocytes in segment 5 ( Figure 9 A). Specimen from Isla Margarita with sperm in abdomen having rectangular nucleus, heads trapezium­shaped, and two rounded mitochondria.

MGS: Ventral shield of collar in solid­color, except for the distal end. Segments divided by 2 dark rectangles dorsally, except for the faecal groove. Color uniform ventrally, except for intersegmental lines and pre and post­chaetal lobes.

Remarks: Chone johnstonae sp. nov. and C. diazi sp. nov. are described from Venezuelan waters. The two species have medium­sized radiolar tips, but in C. johnstonae radioles bear narrow flanges (broad in C. diazi ), and the anterior peristomial ring lobe and branchial lobes are not exposed beyond the collar (exposed in C. diazi ). Chone letterstedti ( Kinberg, 1867) described from Cape of Good Hope, South Africa (SMNH 576, holotype) and Chone reayi McIntosh, 1916 from Ireland are similar to C. johnstonae in that the entire length of the mid­dorsal collar margins forms a broad gap; however, C. letterstedti and C. reayi have the posterior peristomial ring collar length 1.5 times longer than the first chaetiger (as long as first chaetiger in C. johnstonae ); C. johnstonae has paleate chaetae with short­sized mucro (medium­sized mucro in C. letterstedti and C. reayi ); C. letterstedti have short radiolar tips (medium­sized in C. johnstonae and C. reayi ); and broad radiolar flanges (narrow in C. johnstonae and C. reayi ).

Etymology: This species is named after Ardis Johnston in recognition of her work and efforts in the collection of the Museum of Comparative Zoology (MCZ), Harvard University, and for the warm support and assistance during my stay in that institution.

Figures

FIGURE 8. Chone johnstonae sp. nov. A) Whole worm, latero­ventral view, B) anterior end, lateral view, C) anterior end, dorsal view, D) pygidium, ventral view, E, I) radiolar tips, lateral radioles, F) branquial lobe, G) dorsal lip, H) transversal section of radiole, median region. A – D) Holotype FSBC I 66736, E – I) Paratype FSBC I 66737. cop: copepod.

FIGURE 9. Chone johnstonae sp. nov. A) Thoracic chaetae, B – E) paleate chaetae, F) bayonet chaetae, G – H) thoracic acicular uncini, anterior part, I – J) elongate, narrowly hooded chaetae, collar, K) last abdominal chaetiger, L) abdominal tori, segment 11, M) abdominal uncini, segment 11, N) abdominal uncini, last tori. A – H from the 5 th thoracic segment. A – N) Holotype FSBC I 66736. oo: oocyte.