Armandia bifida, 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 : 579-582

Armandia bifida n. sp.

( Figs 1 B, 2A–B, 3, 18B)

Material examined. Two specimens in two samples. Holotype: AM W.44696, MI QLD 2366. Paratype: AM W.44117, MI QLD 2422.

Diagnosis. Parapodia biramous, with prechaetal lobe and ventral lobe; anterior parapodial prechaetal lobe notoriously elongated and symmetrically biramous in chaetigers 1 to 3; following chaetigers lacking dorsal ramus and becoming asymmetrically uniramous towards body end. Anal tube somewhat narrower at base and slightly increasing in width towards distal end, becoming tube-like shape; tube opening slightly laterally compressed, directed posteroventrally; posterior border provided with 10–12 pairs of short paired cirri and an internal short anal cirrus.

Description. Based on holotype. Specimen complete, 29.0 mm long and 2.5 mm wide, with 39 chaetigers. Body slender, slightly tapering towards anterior and posterior ends. Prostomium conical ( Figs 2 A, 3A) excluding palpode, longer than wide; palpode very short. A pair of small red eyes deeply embedded in prostomium. One pair of ring-shaped nuchal organs ( Fig. 3 A); pharynx eversible ( Fig. 2 A) provided with several oral tentacles. Branchiae present from CH 2 to last body chaetiger ( CH 39), long, not decreasing in length towards posterior chaetigers, not meeting middorsally ( Figs 2 A–B, 3A–C); branchiae of last chaetigers with brown spots at midlength/distal third. Parapodia biramous, with prechaetal lobe and ventral lobe on each parapodium. Anterior parapodial prechaetal lobe notoriously elongated and symmetrically biramous in CH 1– CH 3 ( Fig. 3 A, D–E); following chaetigers lacking dorsal ramus and becoming asymmetrically uniramous towards body end ( Fig. 3 F–I). Ventral ramus of prechaetal lobe with two conspicuous notches in CH 2– CH 6 ( Fig. 3 E–G). Elongated ventral lobe in all chaetigers; dorsal cirrus not present. Simple capillary chaetae in two bundles; notochaetae slightly longer than neurochaetae, of same length in all chaetigers and about as long as branchiae. Lateral eyespots anterior to parapodia on 11 chaetigers ( CH 7– CH 17), orange, horizontally oval; eyespots of CH 7 and CH 15– CH 17 much smaller than others. Anal tube somewhat narrower at base and slightly increasing in width towards distal end, becoming tube-like shape ( Figs 2 B, 3B–C), as long as last 5–6 chaetigers. Anal tube opening slightly laterally compressed, directed postero-ventrally, appearing obliquely truncate in lateral view ( Fig. 3 C). Posterior border provided with 10–12 pairs of short paired cirri, about 1/10 as long as anal tube, and an internal, unpaired anal cirrus, short and thin, not easily visible through tube wall ( Fig. 3 C). Pair of short basal cirri not observed.

Remarks. Armandia bifida n. sp. is characterised by: 1) the large body size and the large number of chaetigers (39); 2) the bifid shape of the prechaetal lobe in CH 1– CH 3; 3) the presence of branchiae from CH 2 to the last chaetiger, and 4) the distinct tubular, distally-truncated shape of the anal tube. The photograph of the paratype AM W.44696 ( Fig. 2 A–B) when still alive shows the pharynx extruded with at least 12 oral tentacles of same length in a continuous series. Once the specimen was fixed, only three tentacles could be seen externally. Gallardo (1967) illustrates the oral tentacles of A. leptocirris (Grube, 1878) and A. longicaudata ( Caullery, 1944) found at the Nha Trang Bay, South Vietnam. That paper was also unique in providing a key for opheliids mostly based on the shape and number of the afore-mentioned tentacles instead of using the shape of the anal tube ( Gallardo 1967). However, the usefulness of oral tentacles as discriminating character at the species level is doubtful because either needs the observation of live specimens or dissection of fixed material. On the other hand, the paratype AM W.44696 also shows the same number of chaetigers (39), bears brown spots on branchiae in the last segments and the lateral eyes have the same distribution as in the holotype. The specimen bears an internal long unpaired anal cirrus which seems to have been lost in the holotype (dotted line in Fig. 3 C).

Armandia bifida n. sp. is similar to Armandia longicaudata ( Caullery, 1944, as Ammotrypane ) from Java ( Figs 17 G, 18B), and later reported in South Vietnam ( Gallardo 1967), South Africa ( Fig. 17 H) ( Day 1967) and the Solomon Islands ( Gibbs 1971) ( Fig. 18 B). This species shares with A. bifida n. sp. the presence of an elongated prechaetal lobe, which is about as long as the branchiae in the specimens from East Indies ( Caullery 1944, Fig. 35A) and slightly shorter than those from South Africa ( Day 1967, Fig. 25.2.a); this lobe is, however, not bifid as occurs in A. bifida n. sp. The anal tube is longer in Caullery’s specimens ( Caullery 1944, Fig. 35B) than in South Africa specimens ( Day 1967, Fig. 25.2.c), which is, in turn, similar to that of A. bifida n. sp. The original description of A. longicaudata ( Fig. 17 G) mentions paired anal cirri similar to those of A. bifida n. sp. while in A. longicaudata sensu Day ( Fig. 17 H) they are much larger. Therefore, we suspect that South African specimens may correspond to a different, still undescribed species.

Etymology. The epithet bifida (L.) refers to the conspicuous bifid shape of the prechaetal lobes of the first three chaetigers.

Habitat / Distribution. Intertidal (0–1.5 m) in sandy bottoms off Casuarina beach , in front of Lizard Island Research Station (LIRS) ( Fig. 1 B).

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 3. Armandia bifida n. sp. (holotype AM W. 44696). A. Anterior end, left side, lateral view; B. Posterior end, dorsal view; C. Posterior end, right side, lateroventral view; (D – I) Parapodia, left side: D. CH 1, lateral view; E. CH 3, lateral view; F. CH 4, dorsolateral view; G. CH 6, lateral view; H. CH 36, dorsal view; I. CH 38, dorsal view. White arrows pointing notches of prechaetal lobes ventral ramus. Dotted line in C showing potential contour of unpaired anal cirrus (broken in this specimen) according to that preserved in paratype W. 44117. Proximal part of chaetae only illustrated in D and H.

FIGURE 17. Posterior body region of species of Armandia described or reported in the South East Asia and Australia, all redrawn from original; type locality or collecting site between brackets (see text). Organized alphabetically and by date. A. A. andamana (in Eibye-Jacobsen 2002); B. A. bilobata (in Hartmann-Schröder 1986); C. A. bipapillata (in Hartmann-Schröder 1974); D. A. broomensis (in Hartmann-Schröder 1979); E. A. exigua (in Kukenthal 1887); F. A. leptocirris (in Day 1967); G. A. longicaudata (in Caullery 1944); H. A. longicaudata (in Day 1967); I. A. secundariopapillata (in Hartmann-Schröder 1984).

FIGURE 18. A. World map showing type localities of several Armandia species reported from East Asia and Australasia. B. Map showing records of Armandia species described (grey circles) or reported (white circles) in East Asia and Australasia. 1. Grube (1878); 2. Webster (1884); 3. Kükenthal (1887); 4. Fauvel (1902); 5. Willey (1905); 6. Gravier (1905); 7. Augener (1924); 8. Caullery (1944); 9. Benham (1950); 10. Gallardo (1967); 11. Gibbs (1971); 12. Knox & Cameron (1971); 13. Hutchings & Rainer (1979); 14. Hartmann-Schröder (1974); 15. Hartmann-Schröder (1979); 16. Hartmann-Schröder (1981); 17. Hartmann-Schröder (1984); 18. Hutchings & Murray (1984); 19. Hartmann-Schröder (1986); 20. Saito et al. (2000); 21. Eibye-Jacobsen (2002); 22. Al-Hakim & Glasby (2004); 23. Morton & Bamber (2008); 24. This study.