Protoariciella, Hartmann-Schroder, 1962

Zhadan, Anna, 2020, Review of Orbiniidae (Annelida, Sedentaria) from Australia, Zootaxa 4860 (4), pp. 451-502 : 498

Protoariciella (?) sp. A

Figure 28

Material examined. Queensland: Lizard Island, off Chinamans Head , 14°40’S, 145°27’E, depth 7 m, 28.07.1977, coll. P.A. Hutchings, AM W.43256, 1 specimen on SEM stub .

Description. Specimen incomplete posteriorly, in poor condition. Body length about 5 mm, 42 chaetigers, width 170 µm ( Fig. 28A, B, G ). Transition from thorax to abdomen indistinct ( Fig. 28A, G ). Prostomium short, round, without eyes; two indistinctly separated peristomial segments ( Fig. 28B, C ). Large ventral bulb ( Fig. 28C, G ). Branchiae absent at least on six anterior chaetigers, present at least on some middle segments; cirriform, same length with notopodia ( Fig. 28E ). Notopodial postchaetal lobes digitiform; neuropodial lobes reduced ( Fig. 28B, D, E ). Notochaetae short and long crenulated capillaries in anterior segments, long capillaries only in posterior notopodia ( Fig. 28D, E, H, I ); forked chaetae absent. Neurochaetae capillaries in thorax, crenulated and smooth capillaries and one curved serrated hook in abdomen ( Fig. 28 C–E, F, I).

Remarks. The specimen studied here differ greatly from other Protoariciella specimens owing to the absence of uncini in the thoracic neuropodia, absence of forked chaetae, and single serrated hook in the abdominal neu- ropodia. This possibly represents a new genus, but the poor condition of the single specimen does not allow the establishment of a genus with certainty. The chaetal pattern is similar to that of Paraorbiniella paucibranchiata Rullier, 1974 , described from Cuba. However, this species only has a few pairs of branchiae in the anterior segments, whereas our specimen has branchiae in some abdominal segments. The specimen studied here likely represents 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 28. Protoariciella (?) sp. A, AM W.43256.A–F: SEM, G–I: compound microscope.A. General view; B. anterior end, dorso-lateral view; C. Anterior end, ventral view; D. Anterior parapodia; E. Posterior parapodia; F. posterior neuropodium with hook; G. General view; H. Anterior parapodia; I. Posterior parapodia. cc, crenulated capillaries; sh, serrated hook.