Chone kroyerii Sars, 1862

Tovar-Hernández, María Ana, 2007, On some species of Chone Krøyer, 1856 (Polychaeta: Sabellidae) from world-wide localities, Zootaxa 1518, pp. 31-68 : 45-46

Chone kroyerii Sars, 1862

Figure 8

Chone kr ø yerii Sars, 1862: 35 –37.— Cochrane, 2000: 144 –145.

Material examined. Non-type material. Bogestr Ø mmen [ ZMO] (1).

Additional material. Chone duneri Malmgren, 1867 [ ZMUC POL –1755, Norway]. Chone infundibuliformis Kr ø yer, 1856 [ ZMUC POL –1749, paralectotype].

Description. Colour, body shape, and size. Body cream-coloured, no branchial crown. Trunk cylindrical. Body length 24 mm, width 0.4 mm. Tube unknown.

Branchial lobes and branchial crown. Insertion of the branchial crown not exposed beyond collar ( Fig. 8 B).

Peristomium . Anterior peristomial ring lobe (aprl) not exposed beyond collar, distally entire, triangular ( Fig. 8 B). Posterior peristomial ring collar: antero-dorsal, ventral and lateral margins entire, ventral margin higher than dorsal ( Fig. 8 D); longitudinal grooves on dorsal side of collar; entire length of mid-dorsal collar margins forms a broad gap ( Fig. 8 B). Dorsal pockets well developed. Ventral shield of collar rectangular (not easily discernible). Ratio of posterior peristomial ring collar length versus chaetiger 2 length, in lateral view: 2:1.

Thorax. Chaetigers 2 to 8: notopodia– two irregular rows of elongate, narrowly hooded chaetae; one anterior row with narrow bayonet chaetae ( Fig. 8 H); two posterior rows with symmetrical; paleate chaetae with a medium-sized mucro ( Figs 8 E–G); neuropodia– two irregular rows of acicular uncini per torus, main fang surmounted by three rows of teeth ( Fig. 8 J), second tooth enlarged, located in the midline, dentition covering one quarter of the main fang length. Glandular ridge on chaetiger 2: narrow.

Abdomen. Abdominal segments: 51. Anterior abdominal uncini with the main fang surmounted by five rows of teeth equal in size ( Fig. 8 K), occupying less than half the length of main fang, main fang not extending beyond breast, breast rectangular. Posterior abdominal uncini with four rows of teeth equal in size ( Fig. 8 L). Very long, narrowly hooded chaetae ( Fig. 8 I). Pygidium with triangular posterior margin ( Fig. 8 D).

Gametes. Male with spermatozoa in thorax and abdomen: acrosome elongate, triangular, nucleus barrelshaped, two rounded mitochondria ( Fig. 8 C).

Methyl green staining. Collar dorsal and lateral surfaces completely stained ( Figs 8 B, D), collar ventral surface coloured only the base of the ventral collar shield ( Fig. 8 A), other areas with small dark points. Thorax dorsally less stained than ventrally ( Fig. 8 B).

Remarks. Sars (1862) stated that the specimens resembled Chone paucibranchiata (Kr ø yer, 1856) to such an extent that he was long predisposed to assume that taxon; however, the number of radioles is not a character to differentiate species and the biannulate condition in thoracic segments is a common pattern in Chone . Chone kroyerii was referred to C. infundibuliformis by Malmgren (1866) and Fauvel (1927), but Cochrane (2000) recognized this taxon as valid. Chone kroyerii , C. duneri and C. infundibuliformis have anterior and posterior abdominal uncini with similar shape (not modified); C. kroyerii and C. infundibuliformis have the branchial lobes not exposed beyond collar (exposed in C. duneri ); C. kroyerii has a broad collar gap (narrow in C. infundibuliformis ), and the ventral margin of collar higher than C. infundibuliformis . Among species of Chone included in this revision, C. kroyerii is unique by having a rectangular ventral shield of collar ( Table 2 ).

Figures

FIGURE 8. Chone kroyerii. (A) Anterior end, ventral view; (B) same, dorsal view; (C) spermatozoon; (D) body, lateral view; (E – G) paleate chaetae; (H) bayonet chaeta; (I) very long, posterior abdominal chaeta; (J) thoracic uncinus; (K) anterior abdominal uncinus; (L) posterior abdominal uncinus. (A – B, D) Methyl green staining. (A – L) [ZMO Boūgestrommen].