Armandia laminosa, Parapar, Julio & Moreira, Juan, 2015

Parapar, Julio & Moreira, Juan, 2015, Six new species of the genus Armandia Filippi, 1861 (Polychaeta, Opheliidae) from Lizard Island (Great Barrier Reef, Australia), Zootaxa 4019 (1), pp. 577-603 : 586-590

Armandia laminosa n. sp.

( Figs 1 D, 2E–F, 7–9, 18B)

Material examined. Thirty-seven specimens in ten samples. Holotype: AM W.44702, MI QLD 2421. Paratypes: AM W.43896, MI QLD 2334 (4); AM W.44103, MI QLD 2334; AM W.44109, MI QLD 2340 (8); AM W.44236, MI QLD 2366 (3); AM W.47322, MI QLD 2373 (2); AM W.44296, MI QLD 2373; AM W.44294, MI QLD 2376 (2); AM W.47323, MI QLD 2376 (2 on SEM stub); AM W.44699, MI QLD 2415 (3); AM W.45122, MI QLD 2429 (3); AM W.45127, MI QLD 2432 (3); AM W.47324, MI QLD 2432, in EtOH; AM W.45126, MI QLD 2433; AM W.45129, MI QLD 2433, in EtOH; AM W.45133, MI QLD 2433.

Diagnosis. Parapodia biramous, with prechaetal lobe and ventral lobe on each parapodium; dorsal cirrus not present. Prechaetal lobes highly asymmetrical; wide and foliose from chaetiger 1 to chaetiger 3, then becoming progressively smaller towards last chaetigers; prechaetal lobe tip ventrally displaced; conspicuous bilobed appearance from midbody to last chaetigers. Anal tube square-shaped, as long as last 2 chaetigers; posterior and ventral margins open, provided with long unpaired anal cirrus, thick at base and distally tapered, projecting outwardly. Posterior border provided with 5–6 pairs of elongate, finger-like, paired anal cirri, almost as long as anal tube, shorter and thinner than pair of clavate basal cirri.

Description. Based on holotype. Specimen complete, 9.0 mm long and 0.8 mm wide, with 27 chaetigers. Body slender, slightly tapering towards anterior end, posterior end truncated ( Fig. 8 A). Prostomium conical ( Figs 2 F, 7A), palpode well-developed, large, clavate ( Fig. 8 B). Eyes not seen. One pair of ring-shaped nuchal organs ( Figs 7 A, 8B); pharynx eversible, oral tentacles not seen. Branchiae present from CH 2 to last body chaetiger ( CH 27), long, reaching chaetal bundle of next chaetiger, not decreasing in length in posterior chaetigers, not meeting middorsally. Parapodia biramous, with prechaetal lobe and ventral lobe on each parapodium; dorsal cirrus not present. Prechaetal lobes highly asymmetrical; wide and foliose from CH 1– CH 3, then becoming progressively smaller towards last chaetigers; prechaetal lobe tip ventrally displaced ( Figs 7 A, C–F, 8C–D, 9E); conspicuous bilobed appearance from midbody to last chaetigers ( Figs 7 G–M, 8E–F, 9A–B). Lateral eyespots anterior to parapodia on 11 chaetigers ( CH 7– CH 17), orange, horizontally oval; those of CH 7 and CH 16– CH 17 smaller than others. Simple capillary chaetae in two bundles, notochaetae generally longer than neurochaetae. Anal tube squareshaped, about as long as wide ( Figs 7 B, 9C–D, F); tube as long as last 2 chaetigers; posterior and ventral margins open, provided with long unpaired anal cirrus, thick at base and distally tapered, projecting outwardly ( Fig. 7 B). Posterior border provided with 5–6 pairs of elongate, finger-like, paired anal cirri, almost as long as anal tube ( Figs 7 B, 9C–D, F), shorter and thinner than pair of clavate basal cirri ( Figs 7 B, 9F).

Remarks. Armandia laminosa n. sp. is mostly characterised by the large size and the foliose shape of the prechaetal lobe in CH 1– CH 3 ( Figs 7 A, C–E, 8D, 9E); this feature is unique among all other species described in Lizard Island and described or reported in Australasia and the South-East Indian region as well. The anal tube is, however, not very distinctive and quite similar to that of A. paraintermedia n. sp. described herein, both considering the shape and size of the tube and the size of the anal cirri (compare Figs 7 B and 10B). The paired anal cirri and the pair of basal cirri are similar in shape and width being the last ones slightly longer than the former. Paratypes measure 3–10 mm in length with 27–28 chaetigers. They still bear the anal tube and all cirri which suggests that those structures are not easily lost; the anal unpaired cirrus also show a conspicuous hook-like shape when is not broken ( Fig. 7 B). The length of the palpophore seems highly variable, sometimes as long as the prostomium (paratype AM W.43896). Observations on live specimens revealed that they conspicuously coil themselves when disturbed ( Fig. 2 E, F).

Etymology. The epithet laminosa refers to the foliose shape of the parapodial prechaetal lobes of the first three chaetigers ( CH 1– CH 3).

Habitat / Distribution. All specimens were found in the West coast of Lizard Island, mostly in front of Casuarina Beach (59.5%) and Vicki’s Reef (32.4%), from the intertidal to 15 m depth in several types of sediments, mainly in sand but also associated with Halophila seagrass ( Fig. 1 D).

Figures

FIGURE 1. Map of the study area showing collecting sites of each species described. Arrows facing to cross-shelf sampling sites: Abbreviations: MGR = MacGillivray Reef, NDI = North Direction Island, YR = Yonge Reef.

FIGURE 2. Macro photographic images of live specimens. (A – B) Armandia bifida n. sp. (paratype AM W. 44696): A. Anterior end, ventral view; B. Posterior end, ventrolateral view; C. Armandia dolio n. sp. (paratype AM W. 45399), ventrolateral view (insert: detail of anal tube); D. Armandia filibranchia n. sp. (paratype AM W. 44115), lateral view; (E – F) Armandia laminosa n. sp. (paratype AM W. 44546): E. Ventrolateral view; F. Lateral view of coiled specimen.

FIGURE 7. Armandia laminosa n. sp. (holotype AM W. 44702). A. Anterior end, right side, lateral view; B. Posterior end, left side, lateral view; (C – M) Parapodia, right side, anterolateral view: C. CH 1; D. CH 2; E. CH 3; F. CH 4; G. CH 6; H. CH 12; I. CH 14; J. CH 19; K. CH 24; L. CH 25; M. CH 27. White arrows point to prechaetal lobe tip. Proximal part of chaetae only illustrated in D and L.

FIGURE 8. Armandia laminosa n. sp. SEM micrographs (paratype AM W. 47323). A. Complete specimen, general view; B. Anterior end, right side, ventrolateral view; C. Anterior chaetigers, right side, ventrolateral view; D. Detail of CH 1 – CH 3, right side, ventrolateral view; E. CH 5, right side, ventroanterior view; F. CH 11, right side, ventroanterior view.