Dialychone okudai, Nishi, Eijiroh, Tanaka, Katsuhiko, Tovar-Hernández, María Ana & Giangrande, Adriana, 2009

Nishi, Eijiroh, Tanaka, Katsuhiko, Tovar-Hernández, María Ana & Giangrande, Adriana, 2009, Dialychone, Jasmineira and Paradialychone (Annelida: Polychaeta: Sabellidae) from Japan and adjacent waters, including four new species descriptions, Zootaxa 2167, pp. 1-24: 14-15

publication ID

http://doi.org/ 10.5281/zenodo.189112

DOI

http://doi.org/10.5281/zenodo.5234003

persistent identifier

http://treatment.plazi.org/id/03B7C922-FFF5-192F-FF2A-50D3FDAFF82B

treatment provided by

Plazi

scientific name

Dialychone okudai
status

new species

Dialychone okudai   new species

Figures 8–9 View FIGURE 8 View FIGURE 9

Material examined. Type material: HOLOTYPE — CBM –ZW 1014, Aikap, Akkeshi, Hokkaido, rocky shore, July 0 1, 1995, by T. Kato. PARATYPES —NHM-ANEA. 2009.15, Aikap, Akkeshi, Hokkaido, rocky shore, July 0 1, 1995, by T. Kato. ZIHU- 3804, Aikap, Akkeshi, Hokkaido, rocky shore, July 0 1, 1995, Coll. T. Kato. USNM 1123950, Daikokujima, Akkeshi, Hokkaido, July 31, 2000, Coll. T. Kato. ECOSUR 0 0 92, Aikap, Akkeshi, Hokkaido, rocky shore, July 0 1, 1995, Coll. T. Kato. ZMUC-POL- 2060, Oshoro, Hokkaido, Kabuto-iso, intertidal, June 12, 1998, Coll. T. Kato. SAMA E 3724, Oshoro, Hokkaido, Kabuto-iso, intertidal, June 12, 1998, Coll. T. Kato. KMHN-IvR- 500.418, Oshoro, Hokkaido, Kabuto-iso, intertidal, April 12, 1995, Coll. T. Kato.

Description Body cream colored in preserved specimen. Trunk cylindrical, abdomen flattened dorsoventrally. Body length: 25 mm in holotype, 10–25 in paratypes, width: 1.5–1.6 mm in holotype, 0.6 –2.0 mm in paratypes. Tubes thin, membranous. Insertion of branchial lobes not exposed beyond collar ( Figures 8 View FIGURE 8 A–B, 9 A–C). Branchial crown length 5.0 mm in holotype, 4.0– 5.5 mm in paratypes. Nine pairs of radioles in holotype, 9–11 pairs in paratypes, connected for three quarters of length by membrane. Radioles with longest pinnules at three quarters of their length. Radiolar tips wide and short (0.6 mm versus 4.5 mm crown length) ( Figure 9 View FIGURE 9 D). Radiolar skeleton with two rows of cells. Lateral flanges broad along the outer edges of radioles. Dorsal lips pointed, without radiolar appendages ( Figure 8 View FIGURE 8 E). One to 4 pairs of short dorsal pinnular appendages united by web, basal-most usually longest ( Figure 8 View FIGURE 8 E). Paired ventral lips short, broadly rounded. Two or three pairs of long ventral radiolar appendages, reaching one half radiole length. Anterior peristomial ring lobe triangular, distally entire, digitifom, visible beyond collar ( Figures 8 View FIGURE 8 B, 9 A–B). Anterior margin of collar with two v-shaped notches dorsally ( Figures 8 View FIGURE 8 A, 9 C), margin of collar entire lateral and ventral ( Figure 9 View FIGURE 9 A–C). Ventral margin of collar higher than lateral and dorsal ( Figure 9 View FIGURE 9 B). Mid-dorsal collar margin forms narrow gap ( Figures 8 View FIGURE 8 A, 9 C). Dorsal pockets well developed ( Figures 8 View FIGURE 8 A, 9 C). Ventral shield of collar swollen, horseshoe-shaped, 1.5 times wider than long; with an anterior curving belt translucent without staining or white when stained with methyl green ( Figures 8 View FIGURE 8 B, 9 A). Lateral white pad on anterior-lateral to dorsal area of collar ( Figure 8 View FIGURE 8 C). Posterior peristomial ring collar 1.5 times longer than chaetiger l in lateral view. Post-chaetal glandular girdle encircling second chaetiger, uniformly narrow. Ventral thoracic shields absent ( Figures 8 View FIGURE 8 B, 9 A). First thoracic chaetiger with single bundle of long, narrow hooded chaetae. Subsequent thoracic segments each with three kinds of notochaetae: superior group of long hooded chaetae and inferior group of short hooded chaetae and paleate chaetae with long mucros ( Figures 8 View FIGURE 8 D, 9 G) and slender bayonet chaetae ( Figure 9 View FIGURE 9 F). Thoracic notopodia with 23–35 long-handled acicular uncini in each fascicle ( Figure 9 View FIGURE 9 H–I), teeth decreasing gradually in size away from main fang, dentition covers proximal half of main fang ( Figure 8 View FIGURE 8 E–F). Abdomen with 42 segments (32–42). Anterior segments; two rows of 6–7 elongate, narrowly hooded chaetae, chaetae from upper half as long as chaetae in lower row; 10–15 uncini per torus with main fang surmounted by 3–5 rows of equal size teeth ( Figures 8 View FIGURE 8 G–H, 9 J), occupying half the length of main fang, older (dorsal most) uncini smaller than younger uncini (ventral most), main fang not extending beyond breast, breast rectangular with a triangular anterior tip ( Figure 8 View FIGURE 8 H). Posterior segments; one or two very elongate, narrowly hooded chaetae, ca. 50 % longer than in anterior segments; 10–12 modified uncini per torus, with several rows (+ 6) of equal size teeth occupying three quarters of the main fang length ( Figures 8 View FIGURE 8 I, 9 K). Pygidium with a rounded posterior margin.

Glandular pattern: After staining with methyl green, anterior end of the collar not colored, posterior end dark. Curved belt above ventral shield area not stained ( Figure 8 View FIGURE 8 A–B). Shield of collar densely colored. Body colored uniformly dorsal and ventrally.

Remarks: Dialychone okudai   superficially resembles Paradialychone ecaudata   by having radiolar tips wide and short, a web extending three quarters of branchial crown length, long pairs of ventral radiolar appendages and a ventral shield horseshoe-shaped. However, a detailed examination of thoracic and abdominal uncini suggests that D. okudai   belongs in Dialychone   . In addition to D. okudai   , 14 accepted species of Dialychone   are known ( Tovar-Hernández 2008). Among these D. okudai   is unique in having lateral pads on the collar segment, v-shaped notches on dorsal collar margins, paleate chaetae with very long mucros and the anterior peristomial ring lobe digitiform and exposed beyond the collar. For instance, in D. collaris ( Langerhans 1880)   , D. normani ( McIntosh 1916)   , D. dunerificta   (Tovar- Hernández et al 2007), D. longiseta ( Giangrande 1992)   , D. quebecensis   ( Tovar-Hernández 2007 a), D. trilineata   ( Tovar-Hernández 2007 a) and D. trilobata ( Gallardo 1968)   the anterior peristomial ring lobe is bilobed and exposed beyond collar; and triangular with entire tip, not exposed in D. acustica ( Claparède 1870)   , D. perkinsi ( Tovar-Hernández 2005)   , D. albocincta ( Banse 1972)   , D. veleronis ( Banse 1972)   , D. arenicola ( Langerhans 1880)   , D. australiensis ( Hartman-Schröder 1979)   and D. usticensis ( Giangrande et al. 2006)   . Dialychone okudai   is the first species of this genus known from Japan.

Etymology: The species is named in honor of Professor Shiro Okuda (Hokkaido University) who first studied species of Dialychone   (as Chone   ) from Hokkaido in recognition of his many years of dedication to the taxonomy of polychaete worms.

CBM

Natural History Museum and Institute

USNM

Smithsonian Institution, National Museum of Natural History

SAMA

South Australia Museum