Arabella (Arabella) pulvinata Zanol & Ruta, 2015, n. sp.
Creators: name: Zanol, Joana
name: Ruta, Christine
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Eunicida
Oenonidae
Arabella
Arabella pulvinata

description: Arabella (Arabella) pulvinata n. sp.
(Figs 1, 2)
Material examined. Holotype: AM W.44856, MI QLD2438 (1), fixed in formalin, few median chaetigers fixed in ethanol.
Measurements. Table 2.
TABLE 2. Measurements of all specimens examined.
Species AMnumber Conditionof Total Total Length to Width at chaetiger 10 (mm) Widest Width at widest chaetiger (mm) specimen number of length chaetiger with without parapodia chaetiger with parapodia without parapodia chaetigers (mm) 10 (mm) parapodia
Arabella (A.) pulvinata n. sp. W.44856 Complete, RA, 325 85 2.60 1.20 1.00 18 1.75 1.40
RP
Arabella (C.) mutans W.44798 Complete 167 24 2.56 0.92 0.75 21 1.12 0.90 W.44855 Complete 190 40 2.60 1.00 0.80 35 1.17 0.90 W.44892 Complete 241 46 2.75 0.97 0.84 34 1.18 1.00 Incomplete 86 21 2.44 0.84 0.78 15 1.03 0.94 W.44908 Complete 211 41 2.28 0.92 0.77 23 1.05 0.82 Complete 220 49 2.36 0.87 0.75 25 1.05 0.85 Complete, RP 166 35 2.68 1.12 0.87 19 1.25 1.15
Arabella (C.) robusta n. sp. W.43916 Complete ~50 5 1.44 0.48 0.44 40 0.60 0.48 W.44355 Complete 79 15 2.25 0.53 0.45 14 0.57 0.48
Drilonereis cf. logani W.44971 Incomplete 135 21 1.77 0.37 * 17 0.47 *
Drilonereis orensanzi n. sp. W.44913 Complete, RP 398 90 2.60 0.57 0.50 18 0.65 0.57 W.44797 Complete 350 105 2.50 0.42 0.37 16 0.55 0.50 W.44923 Incomplete 144 41 2.85 0.50 * 13 0.52 *
Oenone fulgida W.44796 Complete 160 71 5.40 3.40 2.50 59 4.10 2.50 W.44456 Complete ~190 40 3.44 2.25 1.87 43 2.31 1.56
Oenone ventrioculata n. sp. W.44002 Complete ~120 17 1.80 1.00 0.75 37 1 0.87
W.44354 Incomplete 34 5.3 1.90 0.80 0.60???
Oenone sp. 1 W. 44342 Incomplete 44 5 1.1 0.55 0.42 10 0.55 0.42
, Australia Museum. RP, regenerating posterior end. RA, regenerating anterior end. *, parapodia minute at this chaetiger.?, uncertain, specimen incomplete and poorly preserved at posterior region of the
fragment.
Description. Live specimen whitish with internal red hues due to blood (Fig. 1 A, B). Preserved specimen brown; parapodia, anterior and posterior ends lighter, yellowish; distal end of post-chaetal lobe brown (Fig. 1 C, D); some chaetigers with discontinuous dark brown pigmentation on dorsal side. Body long, slender, widest region starting at chaetiger 18, remaining of the body about the same width along its whole length, slowly tapering at posterior region (Fig. 1 A, F); dorsoventrally rounded, more convex dorsally than ventrally anteriorly.
Prostomium longer, narrower and around 2/3 as deep as peristomium; tapering; posterior deeper than anterior end; dorsally in a slope with median groove from posterior to anterior; ventrally flattened with median groove wider and bearing a projection at posterior end (Fig. 1 B–E). Five round eyes in line; 3 median closer to each other than to lateral, smaller and more conspicuous than lateral. Peristomium double ringed, second a little longer, wider and deeper than first (Fig. 1 C, D).
Mandibles as far forward as maxillae in pharyngeal bulb while retracted; cutting plates shorter than mandibular carrier, rounded, inner edge shorter than lateral, widest at anteriormost edge (Fig. 1 G). Maxillae dorsal carriers widest at anterior end; ventral carrier tapering to fine point, shorter than half the length of dorsal carriers (Fig. 1 H). Maxillae with five pairs of plates, asymmetrical considering shape of plates. Both MxI gracile, basally dentate, distally falcate, right bifid. MxII long on both sides (Fig. 1 H–L). MxIII and IV with anteriormost teeth longest. Maxillary formula: (1,8) + (2,8), 12 + 12, 6 + 6, 4 +?, 1 + 1.
Pre-chaetal lobe rounded, as long as chaetal lobe. Post-chaetal tapering to round tips, twice as long as chaetal lobe, decreasing toward posterior end, most posterior a little less than twice as long as chaetal lobe. Notopodial cirri present as small papillae (Fig. 2 B) bearing one to three notoaciculae. Nephridiopore surrounded by ventral pad from chaetiger 11–250, anteriormost inconspicuous, conspicuous from chaetiger 65 (Fig. 1 M, N).
Neuroaciculae mucronate, 4 at most per neuropodia, decreasing in number towards posterior end. Limbate chaetae, decrease in length from dorsal to ventral in all parapodia and in number from anterior to posterior, 6 in anteriormost parapodia (around chaetiger 9), and 4 in median and posterior chaetigers (at least from chaetiger 40) (Fig. 2 A, B). In anteriormost parapodia, dorsalmost limbate chaetae geniculated, 5 more ventral limbate chaetae a little curved. In median and posterior parapodia, 3 dorsalmost limbate chaetae geniculated, first and third finely serrated, second coarsely serrated (6–7 denticles rows); ventralmost chaetae tapering to distal guards gradually (Fig. 2 A–E).
Pygidium with a pair of digitiform dorsal and ventral cirri placed laterally; dorsal ones thicker and twice as long as ventral (Fig. 1 F).
Remarks. Specimen is regenerating first 11 chaetigers and last 84 chaetigers. The third median eye appears to be a duplication of the left one, thus not the normal condition for the species. The normal number of eyes for the species is, probably, four. Right MxIV broke during mounting.
This is the only species examined here to belong to the subgenera Arabella. It differs from all other species of this group by the shape of MxI and MxII and the presence of conspicuous ventral pads surrounding nephridiopores. Arabella (A.) pulvinata n. sp. is most similar to A. (A.) pectinata Fauchald, 1970. They both share mandibular cutting plates longer than mandibular carriers, bifid and simple MxI and similar shape and number of chaetae per parapodium. In addition, considering that the normal condition for A. (A.) pulvinata n. sp. is, probably, four eyes, as discussed under remarks, both species also share the same number of eyes. However, A. (A.) pectinata has left MxI bifid and robust, all teeth of MxIII and IV evenly long and ventral maxillary carriers 2/3 as long as dorsal carriers, features that differentiate both species.
Etymology. Name refers to pads at ventral side that surround nephridiopores.
Habitat. Muddy sand, 0.5 m deep, close to mangroves.
Type locality. Lizard Island, Mangrove Beach.
description: Published as part of Zanol, Joana & Ruta, Christine, 2015, New and previously known species of Oenonidae (Polychaeta: Annelida) from Lizard Island, Great Barrier Reef, Australia, pp. 745-772 in Zootaxa 4019 (1) on pages 748-752, DOI: 10.11646/zootaxa.4019.1.26, http://zenodo.org/record/235654