Six new species of the genus Armandia Filippi, 1861 (Polychaeta, Opheliidae) from Lizard Island (Great Barrier Reef, Australia)AuthorParapar, JulioAuthorMoreira, JuantextZootaxa201540191577603journal article10.11646/zootaxa.4019.1.19a552e02c-9ad5-4f9e-aeb0-ff02489dc5161175-5326241350C06C733D-924E-4124-AECA-E5C094C9E588Armandia dolion. sp.
(
Figs 1
B, 2C, 4–5, 18B)
Material examined.
Eight specimens in four samples.
Holotype
: AM W.44241, MI QLD 2373.
Paratypes
: AM W.43898, MI QLD 2333 (2); AM W.47320, MI QLD 2373 (2); AM W.47321, MI QLD 2373, on SEM stub; AM W.45399, MI QLD 2440; AM W.44557, MI QLD 2330, in EtOH.
Diagnosis.
Parapodia biramous, with prechaetal lobe and ventral lobe; prechaetal lobe symmetrical, with a notch giving distal border a bilobed appearance. Anal tube barrel-shaped, straight at base, increasing width at midline and tapering again towards distal end; anal tube opening directed posteriorly, not laterally compressed; posterior border provided with 10 pairs of short paired anal cirri of different length, about 1/5 as long as anal tube length; internal unpaired anal cirrus and pair of basal cirri present.
FIGURE 4.Armandia dolion. sp.
(holotype; AM W.44241). A. Anterior end, lateral view; B. Posterior end, lateral view; (CH) Parapodia, left side, lateral view: C. CH1; D. CH2; E. CH6; F. CH19; G. CH25; H. CH27. Proximal part of chaetae only illustrated in C–D and G–H.
Description.
Based on
holotype
. Specimen complete, 8.0 mm long and 1.0 mm wide, with 29 chaetigers. Body slender, slightly tapering towards anterior and posterior ends. Prostomium conical, palpode short and clavate (
Figs 4
A, 5A). A pair of small red eyes deeply embedded in prostomium (
Fig. 4
A). One pair of ring-shaped nuchal organs (Fig. 5A–B); pharynx eversible (
Fig. 4
A), oral tentacles not seen. Branchiae present from
CH
2–
CH
26, long, almost reaching dorsal midline, not decreasing in length in posterior chaetigers. Parapodia biramous, with prechaetal lobe and ventral lobe (
Figs 4
C–H, 5C–D); dorsal cirrus from
CH
4. Prechaetal lobe symmetrical, with a notch giving distal border a bilobed appearance (
Fig. 4
C–H). 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, very long capillary chaetae in two bundles; notochaetae generally longer than neurochaetae (Fig. 5A, E). Anal tube barrel-shaped, straight at base, increasing width at midline and tapering again towards distal end, as long as last four chaetigers (
Figs 4
B, 5E–F). Anal tube opening directed posteriorly, not laterally compressed. Posterior border provided with 10 pairs of short paired anal cirri of different length, about 1/5 as long as anal tube length (
Figs 4
B, 5F); internal unpaired anal cirrus and pair of basal cirri not seen (but present in several
paratypes
, see below).
FIGURE 5.Armandia dolion. sp.
SEM micrographs
(paratype AM W.47321). A. Anterior end,
dorsal view; B. Protruded
nuchal organ, right side; C. CH1, dorsal view; D. Two
posterior chaetigers, left side, lateral view;
E. Posterior end, left side,
posterolateral view; F. Anal tube opening, detail.
Remarks.
The most remarkable diagnostic feature of
Armandia dolion. sp.
is the unique shape of the anal tube. Observations on live specimens showed that the anal tube seems to be somewhat flexible allowing some degree of variation in its shape, i.e. sometimes looking either inflated or deflated (
Fig. 2
C). The anal tube of fixed specimens does, however, always show a conspicuous inflated shape (
Figs 4
B, 5E).
Paratypes
measure about
6–10 mm
in length and
0.5–0.9 mm
in width; these specimens have the same of numbers of chaetigers and the presence of prostomial eyes as the
holotype
. In contrast, two
paratypes
(AM W.47320 and AM W.43898) show an unpaired anal cirrus and fewer paired anal cirri (<7). The first chaetiger and the last three ones (
CH
27–
CH
29) also lack branchiae and the parapodia show a small dorsal elevation at the level of the postchaetal lobe as well (
Fig. 4
C, H). Furthermore, the anal tube apparently lacks paired basal cirri.
The closest species to
A. dolion. sp.
is
A. paraintermedian. sp.
(see below) according to general body shape but they differ in the shape and features of the anal tube. Thus,
A. dolion. sp.
has a large, barrel-shaped anal tube while in
A. paraintermedian. sp.
the paired anal cirri are comparatively longer and larger when compared to the size of the anal tube.
Etymology.
The epithet
dolio
(L.) refers to the barrel-shaped anal tube.
Habitat / Distribution.
Sublittoral (
5–14 m
) on muddy sand. Most specimens (87.5%) were collected at Vicki’s reef, in front of Palfrey
Island
and remaining ones at NW of Watson’s Bay (
Fig. 1
B).