Phylo fimbriatus ( Moore, 1903 )

Zhadan, Anna, 2020, Review of Orbiniidae (Annelida, Sedentaria) from Australia, Zootaxa 4860 (4), pp. 451-502 : 490

Phylo fimbriatus ( Moore, 1903)

Figure 23

Aricia fimbriata Moore, 1903: 464–467 , Pl. 24, figs 31–35;

Phylo fimbriatus: Hartman 1957: 267 ; Day 1977: 234–235, fig. 3a-e.

Material examined. Victoria: Westernport Bay , 38°22’S, 145°32’E, 20.11.1973, depth 13 m, coll. J. Kudenov, AM W.7444, 1 specimen ; same locality, 26.11.1973, depth 10 m, coll. J. Kudenov, AM W.7445, 1 specimen . Both specimens were previously examined by J. Day.

Type locality. Suruga Bay , Honshu Island, Japan .

Description. Both specimens studied incomplete, thoracic width 2.4 mm and 1.2 mm. Thorax flattened, consisting of 17 and 14 chaetigers correspondingly; abdomen cylindrical ( Fig. 23A, C, G ). Prostomium conical, with sharply pointed tip ( Fig. 23A, C ). Branchiae from chaetiger 5, triangular with tapering tips; in abdomen becoming long and triangular, longer than notopodia in anterior segments, shorter than notopodia in posterior segments ( Fig. 23A, D, G, H, I ). Thoracic notopodial postchaetal lobes developed from first chaetiger, digitate, become branched in 2–7 lobes beginning from second (in smaller specimen from fourth) chaetiger; in anterior abdomen also branched, then becoming long digitate ( Fig. 23A, D, G, H, I ). Thoracic postchaetal neuropodia lobes as ridges with 2–9 papillae; subpodal papillae present on 2 last thoracic and 2–3 first abdominal chaetigers, up to 5 papillae per segment ( Fig. 23B, C, E, F ). Abdominal neuropodia bilobed with outer lobe longer then inner; subpodal flange well developed with long flange papillae (ventral cirri) ( Fig. 23D, G , H–J). Interramal cirri well developed, longer than neuropodia ( Fig. 23H, I ). Notopodial chaetae crenulate capillaries, in abdominal notopodia also forked chaetae present ( Fig. 23H, I, K ). Thoracic neuropodia with 3–5 rows of curved smooth uncini and few thin capillaries in posterior row; five posterior thoracic neuropodia bearing thick dark spines in upper part of anterior row; in smaller specimen spines absent ( Fig. 23B, C, E, F ). Abdominal neuropodia with capillary and flail chaetae ( Fig. 23L ). Both notopodia and neuropodia in abdomen supported by thin straight aciculae ( Fig. 23 H–J).

Distribution. North Japan, Australia, Victoria.

Habitat. Subtidal.

Remarks. Phylo fimbriatus was described from North Japan ( Moore, 1903) and later recorded from Victoria ( Day, 1977). This species is easily distinguishable from other Phylo species by the characteristic branched notopodial lobes. The specimens studied here are in agreement with previous descriptions but should be confirmed by molecular studies.

Figures

FIGURE 23. Phylo fimbriatus, A. AM W.7444, B–L: AM W.7445. A–G: stereomicroscope, methylene blue staining; H–L: compound microscope, chaetigers 30–31.A. Anterior end, dorsal view; B. Thorax-abdomen transition, lateral view; C. Anterior end, lateral view; D. Thorax-abdomen transition, dorsal view; E. Neuropodia of chaetigers 5–7; F. Neuropodia of chaetigers 15–16; G.Abdomen, latero-posterior view; H, I. Abdominal parapodia; J. Abdominal neuropodia; K. Notopodial forked chaeta; L. Neuropodial flail chaeta. a, acicula; br, branchia; cc, crenulated capillaries; fc, forked chaeta; flc, flail chaeta; ic, interramal cirrus; ne, neuropodium; no, notopodium; s, spines; u, uncini.