Leodamas fimbriatus (Hartman, 1957)

Zhadan, Anna, 2020, Review of Orbiniidae (Annelida, Sedentaria) from Australia, Zootaxa 4860 (4), pp. 451-502 : 475-477

Leodamas fimbriatus (Hartman, 1957)

Figure 13

Scoloplos (Leodamas) fimbriatus Hartman, 1957: 293 , Pl. 34, figs.1–5; Day 1977: 232–233.

Material examined. Victoria: Westernport Bay , 38°22’S, 145°32’E, 1 incomplete specimen, AM W.7455.

Type locality. Yorke Peninsula , South Australia .

Description. Thoracic width 1.2 mm; body long, thorax flattened, abdomen cylindrical; 29 thoracic chaetigers ( Fig. 13A ). Prostomium long, conical with tapering tip ( Fig. 13B, C ). Branchiae from chaetiger 7, triangle with tapering tips; in abdomen becoming longer than notopodia ( Fig. 13B, C, E, G ). Thoracic notopodial postchaetal lobes developed from chaetiger 4, narrow digitate ( Fig. 13B, C ). Thoracic neuropodial lobes as low ridges, weakly developed on anterior segments; from chaetiger 22 podal papillae appearing at upper part of ridge; second podal papillae starting from chaetiger 26 ( Fig. 13A, B, D ). Subpodal papillae starting from chaetiger 24, 2–3 per segment; also present on abdominal chaetigers, three per segment in anterior abdomen, then two and then one ( Fig. 13A, D ). Maximally four papillae per parapodia (podal and subpodal papillae combined); all papillae digitate. Abdominal notopodial lobes shorter than branchiae, narrow digitate ( Fig. 13E, G ). Abdominal neuropodial lobes with cirriform outer lobe and short round inner lobe ( Fig. 13E, G, H ). All notopodia bearing crenulate capillaries, besides, forked chaetae present in abdominal notopodia ( Fig. 13H ). Thoracic neuropodia bearing 3–4 rows of smooth curved nonhooded uncini, longer and thicker on chaetigers 14–24, smaller in anterior and posterior thoracic chaetigers ( Fig. 13A, B, D ). In anterior thorax first row of uncini present only in dorsalmost part of neuropodia, and fourth row present only in ventralmost part of neuropodia ( Fig. 13B ); fourth row shorter than others also in posterior thorax ( Fig. 13D ). Shape of uncini differing between rows: in first row medium thick and bent, in second row with maximum thickness and also bent, in third row of medium thickness and less bent, and in fourth row slender and only slightly bent ( Fig. 13F ). Bundle of few capillaries present in upper part of posterior thoracic neuropodia in posterior row ( Fig. 13D ). Both notopodial and neuropodial lobes in abdomen supported by straight aciculae, they emerged in notopodia, projected with obtuse tip in neuropodia ( Fig. 13G, H ).

Distribution. Australia, Victoria, South Australia.

Habitat. Intertidal, sand.

Remarks: Leodamas fimbriatus was described from the Yorke Peninsula, South Australia (Hartman, 1957), and redescribed by Day (1977) from Westernport Bay, Victoria. Day did not find any discrepancies with Hartman’s description and supposed that this species represents a link between Scoloplos and Orbinia . A reinvestigation of the same specimen from Victoria (AM W.7455) examined by Day (1977) showed that the distribution of thoracic uncini is slightly different from the original description. Hartman (1957) stated: “the anterior-most row is longest and has the thickest, largest, and most sharply curved uncini; those in more posterior rows are gradually slenderer”. In the specimen studied here, the anterior row is short and present only in the dorsal-most part of the neuropodia in the anterior thorax, and then becomes the same length as the other rows. Additionally, the maximum thickness of the uncini is present in the second row instead of the first. A reinvestigation of the type material is needed for the clarification of this character in L. fimbriatus . Sun et al. (2018, p.134) confused L. fimbriatus and L. cirratus in the key for Leodamas species (see above, Remarks to L. cirratus ).

Figures

FIGURE 13. Leodamas fimbriatus, AM W.7455. A–E: stereomicroscope, methylene blue staining; F–H: compound microscope.A. General view; B. Anterior end, lateral view; C. Anterior end, dorsal view; D. Thorax-abdomen transition, lateral view; E. Abdomen, lateral view; F. Neuropodia of chaetiger 2, 1–4: number of uncini row, starting from anteriormost; G. Abdominal parapodia; H. Detail of abdominal parapodia, showing aciculae (a) and forked chaetae (fc). br, branchia; cc, crenulated capillaries; ne, neuropodium; no, notopodium; u, uncini.