Armandia amakusaensis Saito, Tamaki & Imajima, 2000

Magalhães, Wagner F., Rizzo, Alexandra E. & Bailey-Brock, Julie H., 2019, Opheliidae (Annelida: Polychaeta) from the western Pacific islands, including five new species, Zootaxa 4555 (2), pp. 209-235 : 219-220

Armandia amakusaensis Saito, Tamaki & Imajima, 2000

Figure 7 (E–F)

Armandia amakusaensis Saito, Tamaki & Imajima, 2000: 2032 –2036, fig. 3.

Material examined. Guam, Mariana Islands: Agana outfall, Sta. A 2R2, 13°29'14" N, 144°44'54" E, in depths ranging from 65 to 100 m, Oct/2005 (1 spm); Apra Harbor, Sta. 5b, 13°27'19.70" N, 144°39'25.67" E, 17 m, Jan/ 2010 (1 spm) .

Diagnosis. Parapodia biramous, with parapodial prechaetal lobe, ventral lobe and minute dorsal cirrus. Anal tube longer than wide, posterior margin with distinct ventral incision and discreet dorsal incision; up to 6 pairs of elongate marginal papillae; a long and crenulate unpaired ventral cirrus; a pair of leaf-like basal papillae.

Description. Two specimens 4.5–7 long, 0.3–0.4 mm wide for 29 chaetigers. Body slender, slightly tapering towards anterior and posterior ends. Prostomium conical to elongate excluding palpode, longer than wide; palpode well developed and clavate. A pair of black eyes deeply and ventrally embedded in prostomium and a third dorsal eye present. One pair of nuchal organs present, ring-shaped. Pharynx and oral tentacles not observed. Branchiae present from chaetiger 2 and present in all segments; short, not meeting mid-dorsally; last 2 chaetigers with very short branchiae, digitate.

Parapodia biramous, symmetrical with parapodial prechaetal lobe, minute dorsal cirrus from chaetiger 2 and ventral lobe. Simple capillary chaetae in two bundles; notochaetae about twice longer than neurochaetae and slightly longer than branchial filaments; 4–6 anteriorly reducing to three posteriorly; neurochaetae 3–4 capillaries anteriorly reducing to three or less posteriorly. Lateral eyespots anterior to parapodia 7 on 11 chaetigers (chaetigers 7–17), black, rounded; eyespots of chaetiger 7, 16, and 17 smaller, also rounded.

Anal tube longer than wide, as long as 3–4 posterior chaetigers; posterior margin with distinct ventral incision and very discreet dorsal incision; a long unpaired crenulate ventral cirrus, thick at base and distally tapered, internally inserted projecting outwardly, one specimen with cirrus 4x longer than length of anal tube; posterior margin provided with up to 6 pairs of elongate marginal papillae, and a pair of leaf-like basal papillae, thicker than marginal papillae ( Fig. 7E, F ).

Remarks. The two specimens from Guam agree well with the original description by Saito et al. (2000). The type material had up to 32 chaetigers (13 mm long) and the specimens from Guam both had 29 chaetigers (largest with 7 mm long). The distinctive feature of this species is the barrel-shaped anal cone with up to 6 pairs of elongate marginal papillae, a pair of basal papillae and very long unpaired cirrus. One specimen from Guam had an anal cirrus with about 4x the length of the anal cone.

Distribution. Originally described from Tomioka Bay on the northwestern corner of Amakusa-Shimoshima Island in western Kyushu, Japan ( Saito et al. 2000) and newly recorded to Guam in the Mariana Islands.

Figures

FIGURE 7. Armandia cf. paraintermedia from American Samoa: A, anterior end in lateral view; B, anterior end showing detail of prostomial palpode and everted pharynx; C and D, pygidium of two individuals in lateral view. Armandia amakusaensis from Guam, Mariana Islands: E and F, pygidium of two individuals in lateral and ventral views, respectively.