Chaetozone Malmgren, 1867

Grosse, Mael, Capa, Maria & Bakken, Torkild, 2021, Describing the hidden species diversity of Chaetozone (Annelida, Cirratulidae) in the Norwegian Sea using morphological and molecular diagnostics, ZooKeys 1039, pp. 139-176 : 139

Genus Chaetozone Malmgren, 1867

Chaetozone Malmgren, 1867: 96; Chambers 2000: 589-591; Blake 2015: 504-507; Blake 2018: 69; Blake 2019: 170-171.

Type species.

Chaetozone setosa Malmgren, 1867 by monotypy.

Diagnosis

(emended). Prostomium blunt to conical, peristomium short to elongate, usually lacking eyespots, with a pair of small nuchal slits or depressions at posterior edge; with a single pair of grooved dorsal tentacles arising from posterior edge of peristomium, or sometimes more posterior on an achaetous anterior segment, or rarely an anterior chaetiger. First pair of branchiae arising from an achaetous segment or chaetiger 1; or sometimes with first two pairs of branchiae on a single anterior segment. Branchiae laterally ciliated in distal half. Body usually expanded anteriorly, rarely with middle or posterior body segments beaded or moniliform; narrowing posteriorly or posterior end often expanded. Chaetae include capillaries on most chaetigers and sigmoid acicular spines in neuropodia and notopodia; capillary chaetae typically smooth or with sparse to dense fibrillation, fibrils generally homogeneously spread or grouped on one side of the blade, rarely arranged in concentric rings; some species with long, natatory-like capillaries, sometimes limited to gravid individuals; spines typically concentrated in posterior segments, forming distinct cinctures with spines carried on elevated membranes; cinctures with few to many spines sometimes encircling entire individual posterior segments, accompanied with none to many alternating capillaries; bidentate spines sometimes present in juveniles or occasionally accompanying unidentate spines in ventral most position of far posterior chaetigers of adults. Pygidium a simple lobe, disk-like, or with long, terminal cirrus.

Remarks.

Based on observations from SEM images from several species in this study, the presence of cilia on the branchiae (Fig. 2 ) is added to the previously emended diagnosis ( Blake 2019).

Figures

Figure 2. SEM of branchial anatomy, specimen ZMBN 125776 (Chaetozone sp. 4) A whole branchia B detail of distal end C detail of lateral cilia D detail of distal half morphology E detail of proximal half morphology.