Leodamas johnstonei ( Day, 1934 )

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

Leodamas johnstonei ( Day, 1934)

Figure 14

Scoloplos johnstonei Day, 1934: 58–60 , fig.1l a–e.

Scoloplos (Leodamas) johnstonei: Hartman 1957: 290 ; Day 1967: 550, fig. 23.5 k–o; Day 1977: 231–232.

Scoloplos (Leodamus) uniramus Day 1961: 477–479 , fig. 1g–o; Day, 1967: fig. 23.6. a–f.

Material examined. New South Wales: Akuna Bay, Hawkesbury River , 33°38’36”S, 151°14’12”E, November 1991, coll. C.L. Rose, depth 13.4 m, fine mud, AM W.24102, 5 specimens ; Burwood Beach , 32°37’S, 151°44’E, AM W.8889, 1 specimen .

Type locality. St. James , South Africa .

Description. All specimens incomplete. Small worms, thoracic width 0.5–0.9 mm. Body long and slender, thorax flattened, abdomen cylindrical ( Fig. 14A ). Prostomium conical, long, sharply pointed ( Fig. 14A, C ). Thoracic chaetigers numbering 15–24. Branchiae from chaetiger 6, trianglular with tapering tips; in abdomen becoming narrow digitiform ( Fig. 14 C–F). Thoracic notopodial postchaetal lobes developed from chaetiger 4, narrow digitate, in abdomen retaining same shape, equal or slightly shorter than branchiae ( Fig. 14 A–E). Thoracic neuropodial postchaetal lobes weakly developed, as low ridges; posterior thoracic neuropodia with podal papillae; first podal papilla appearing in upper part of neuropodial ridge, last thoracic neuropodia with two podal papillae, in upper and lower part ( Fig. 14A, B ). Subpodal papillae developed on posterior thoracic and anterior abdominal segments. Last thoracic chaetiger bearing three papillae in total ( Fig. 14B ). Abdominal neuropodia bilobed, with outer lobe cirriform, inner lobe short and round ( Fig. 14 D–F). First 10–15 abdominal parapodia with cirriform subpodal papillae, anterior segments with two papillae, following with one ( Fig. 14B ). Notopodia with crenulate capillaries throughout, also with forked chaetae in abdominal segments ( Fig. 14G ). Thoracic neuropodia with four to five rows of curved uncini; in first four rows similar in size and shape; fifth row shorter, only in lower part of neuropodia, uncini thinner and less curved ( Fig. 14B ). Single capillaries present in upper and middle part of posterior row only on few posterior thoracic neuropodia ( Fig. 14B ). Abdominal neuropodia with one stout almost straight acicula with blunt tip and bundle of capillaries and flail chaetae with sharp transition to very thin arista ( Fig. 14E, F ). Abdominal notopodia with capillaries and forked chaetae ( Fig. 14G ).

Distribution. South Africa ( Day 1934), Australia, Queensland, New South Wales, Victoria.

Habitat. Intertidal and upper subtidal, muddy sand, mud.

Remarks: Leodamas johnstonei was originally described from South Africa as Scoloplos johnstonei . Hartman (1957) transferred this species to the subgenus Leodamas . She erroneously stated the absence of podal and subpodal lobes (papillae). Later, Day described a similar species that was also described from South Africa, S. (L.) uniramus . This species differed from L. johnstonei owing to the uniramous shape of the abdominal neuropodia, smaller number of thoracic chaetigers, slenderer notopodial lobes and branchiae, and presence of flail chaetae in the abdominal neuropodia. An investigation of the Australian material showed that these two species were synonymous ( Day 1977). The present study confirms the presence of flail chaetae in the Australian specimens of L. johnstonei . The shape of the abdominal neuropodia is biramous with a reduced inner lobe, which is typical for Leodamas species. However, whether the Australian and South African specimens belong to the same species needs to be confirmed.

Figures

FIGURE 14. Leodamas johnstonei, AM W.8889. A–D; stereomicroscope, methylene blue staining; E–G: compound microscope.A.Anterior part of the body, lateral view; B. Thorax-abdomen transition, lateral view; C. Anterior part of the body, dorsal view; D. Abdomen, posterior view; E, F. Abdominal parapodia; G. Abdominal notochaetae. a, acicula; br, branchia; cc, crenulated capillaries; fc, forked chaeta; flc, flail chaeta; ne, neuropodium; no, notopodium.