Australaugeneria iberica, Ravara, Ascensão & Cunha, Marina R., 2016

Ravara, Ascensão & Cunha, Marina R., 2016, Two new species of scale worms (Polychaeta: Aphroditiformia) from deep-sea habitats in the Gulf of Cadiz (NE Atlantic), Zootaxa 4097 (3), pp. 442-450 : 445

Australaugeneria iberica sp. nov.

Figure 2

Type material. Atlantic Ocean. Gulf of Cadiz: Carlos Ribeiro MV, St JC10_051, ca. 2230 m, 3 incompl. spms ( NHMUK 2016.347, holotype; DBUA 0001726.01, paratypes).

Description. Examined specimens incomplete, only one specimen with one elytron. Larger fragment with 18 segments, 5.09 mm long and 1.09 / 2.69 mm wide without and with parapodia, respectively. Body without pigmentation pattern or dorsal tubercules, compressed dorsoventrally, gradually tapering anteriorly and posteriorly. Elytra scars on segments 2, 4, 5, 7, alternating to the end of fragment. Elytra large, covering the dorsum, delicate and transparent, without tubercles or papillae. Prostomium rounded, bilobed anteriorly, without cephalic peaks; eyes not visible ( Fig. 2 A). Median antenna very long (reaching 3rd chaetiger), smooth, gradually tapering distally, ceratophore inserted in anterior notch. Lateral antennae very short, piriform, ceratophores inserted ventrally. Palps stout, smooth, gradually tapering, about half the length of median antenna. First segment not visible dorsally, without chaetae; two pairs of tentacular cirri, dorsal cirri about as long as median antenna with large ceratophore, ventral cirri much shorter, similar in length to palps, with shorter ceratophore. Parapodia of buccal segment (segment 2) not modified ( Fig. 2 B); ventral cirri similar in length to the following ones; hooked chaetae present. Pharynx not observed. Parapodia of median segments relatively long, sub-biramous. Notopodia with long projecting acicular lobe, extending to near distal end of neuropodial lobes or beyond in posterior parapodia ( Fig. 2 C, D). Dorsal cirri much longer than parapodia including chaetae, smooth, tapering gradually to filiform tips, present on segments without elytra, attached at the base of notopodia. Neuropodia deeply incised dorsally and ventrally, with longer bilobed prechaetal lobes, and shorter rounded to slightly bilobed postchaetal lobes. Ventral cirri slightly longer than neuropodia, smooth, gradually tapering to filiform tips. Notochaetae stout, spinulose, with entire tips, present from segment three ( Fig. 2 F–H). Neurochaetae of segment two stout hooks ( Fig. 2 E); remaining parapodia with two types of neurochaetae: upper group slightly slender, spinulose, with bidentate tips ( Fig. 2 I, J); lower group stouter, falcate, smooth or faintly spinous ( Fig. 2 K, L). Pygidium not observed.

Type locality. Gulf of Cadiz (NE Atlantic), Carlos Ribeiro mud volcano, 35˚47.102'N, 08˚25.309'W, 27 May 2007, JC10 Leg1 (RRS James Cook).

Distribution. Northeast Atlantic (Gulf of Cadiz).

Habitat. In association with one alcyonarian colony (cf. Acanella sp.), collected at the flank (no methane seepage detected) of Carlos Ribeiro MV, at 2230 m water depth.

Etymology. The species name refers to its type locality on the Iberian margin.

Remarks. The genus Australaugeneria includes three species, A. rutilans ( Grube, 1878) and A. michaelseni Pettibone, 1969 a, both from southwest Australia, 11–16 m depth, and A. pottsi Pettibone, 1969 b from the Maldives Islands. Recently, A. rutilans was also reported from the Red Sea ( Wehe, 2006). Australaugeneria iberica sp. nov. differs from the other three species in having neuropodial hooks on segment two only (instead of two and three) and prechaetal lobes of the first parapodia are not enlarged or hood-like. Both characters are diagnostic of the genus and its diagnosis is emended here. Further differences between the four species are highlighted in Table 2 . This is the first deep-sea species of the genus, as well as the first record for the Atlantic Ocean.

Figures

FIGURE 2. Australaugeneria iberica sp. nov. Holotype. A—Anterior end, dorsal view B—First parapodium, dorsal view C— Posterior parapodium, anterior view D—same, posterior view, with representation of chaetae E—Neurochaeta, first parapodium F—Notochaeta, third parapodium G—Notochaeta, fourth parapodium H—Notochaeta, posterior parapodium I— Upper neurochaeta, fourth parapodium J—Upper neurochaeta, posterior parapodium K—Lower neurochaeta, fourth parapodium L—Lower neurochaeta, posterior parapodium. Scale bars (µm): A = 500, B – D = 100, E – L = 50.

Tables

TABLE 2. Morphological differences between the four species of the genus Australaugeneria (modified from Pettibone 1969 a).

A. rutilans	A. michaelseni	A. pottsi	A. iberica sp. n.
Eyes present	absent	absent	absent
First parapodia enlarged	strongly enlarged	slightly enlarged	not enlarged
Neuropodial hooks on segm. 2 and 3 (strongly bent)	on segm. 2, 3 and 4	on segm. 2, 3 and 4	on segm. 2 (slightly bent)