Protoariciella cf. heterosetosa Hartmann-Schröder, 1962

Zhadan, Anna, 2020, Review of Orbiniidae (Annelida, Sedentaria) from Australia, Zootaxa 4860 (4), pp. 451-502 : 494-496

Protoariciella cf. heterosetosa Hartmann-Schröder, 1962

Figure 26

Protoariciella heterosetosa Hartmann-Schröder, 1962: 131–133 , fig. 157–160.

Material examined. Queensland: Lizard Island, off Chinamans Head , 14°40’S, 145°27’E, depth 7 m, 08.01.1977, coll. P.A. Hutchings, P.B. Weate, AM W.43257, 1 specimen on SEM stub .

Type locality. Taltal , Chile .

Description. Specimens entire, body length 7–8 mm, 66–70 chaetigers, width 0.3–0.4 mm ( Fig. 26A, B, K ). Prostomium short, round, without eyes; two peristomial segments ( Fig. 26B, K ). Transition from thorax to abdomen indistinct ( Fig. 26A, K ). Branchiae from chaetiger 8; narrow triangular shorter than notopodia in anterior and posterior part, longer in middle; absent on five posteriormost segments ( Fig. 26 B–D, F). Notopodial postchaetal lobes digitiform; neuropodial lobes shorter, triangle in anterior part, digitiform with widened base in posterior ( Fig. 26C, D, F , J–I, L, M). Pygidium without cirri ( Fig. 26C ). Notochaetae long crenulated capillaries in all segments, in abdominal notopodia also 1–2 forked chaetae present ( Fig. 26C, D , F–H, J, M). Neurochaetae long and short crenulated capillaries and 2–4 straight serrated uncini in thorax, crenulated capillaries and one curved smooth hook in abdomen ( Fig. 26D, E , G–I, L, M). All uncini unidentate.

Remarks. Protoariciella heterosetosa was described from Taltal ( Chile, East South Pacific). It differs from other Protoariciella species owing to a combination of the following characters: branchiae starting from chaetiger 8, short rounded anterior parapodial lobes, pygidium without cirri, one forked chaeta in the posterior notopodia, unidentate neuropodial uncini, and is serrated in the anterior segments but smooth in the posterior segments. The specimens studied here are similar regarding the starting-point of the branchiae segment and shape/distribution of the chaetae, except for the number of forked chaetae in the middle and posterior notopodia, which can be two instead of one. Our specimens differ in terms of the absence of eyes, shape of the anterior parapodial lobes, which are digitiform in notopodia, and triangular instead of rounded neuropodia. Previously, one species of Protoariciella was described from Australia: Protoariciella australiensis Hartmann-Schröder, 1981 . It differed from other species of the genus owing to the branchiae starting from chaetiger 6, presence of forked chaetae in all abdominal notopodia, unidentate uncini, some hooded uncini, and pygidium with 4 short cirri. The specimens studied here differ owing to the starting-point of the branchiae segment (8 vs. 6), branchiae longer than notopodial lobes, absence of anal cirri, and absence of hoods in all posterior uncini. Another species reported from the West Pacific is Protoariciella tuamotuensis Hartmann-Schröder, 1992 . It differs from P. australiensis and from our specimens by the presence of branchiae from chaetiger 5, presence of subuluncini in the posterior notopodia, and shape of the parapodial lobes, which are long and finger-shaped in both the notopodia and neuropodia. The specimens studied here likely represent a new species; but due to the few poorly preserved specimens and the limited knowledge of the important taxonomic characters in this genus, it is not described as a new species.

Figures

FIGURE 26. Protoariciella cf. heterosetosa, AM W.43257. A–J: SEM, K–M: compound microscope. A. General dorsal view; B. Anterior end, dorsal view; C. posterior end, dorsal view; D. anterior parapodia, lateral view; E. anterior neuropodium, lateral view; F. Middle body, dorso-lateral view; G, H. Posterior parapodium; I. Posterior neuropodium; J. Posterior notochaetae; K. anterior end, ventral view; L. Anterior parapodia; M. Posterior parapodia. cc, crenulated capillaries; fc, forked chaeta; h, hook; u, uncini.