Armandia buccina, Moreira, Juan & Parapar, Julio, 2017

Moreira, Juan & Parapar, Julio, 2017, New data on the Opheliidae (Annelida) from Lizard Island (Great Barrier Reef, Australia): five new species of the genus Armandia Filippi, 1861, Zootaxa 4290 (3), pp. 483-502 : 484-490

Armandia buccina n. sp.

( Figs 1–4 )

Material examined. Eleven specimens in six samples. Holotype: AM W.49287, MI QLD 2376. Paratypes: AM W.49288, MI QLD 2355 (1); AM W.49289, MI QLD 2340 (1); AM W.49290, MI QLD 2376 (2); AM W.44554, MI QLD 2376 (1, fixed in EtOH); AM W.44548, MI QLD 2387 (anal tube only); AM W.44561, MI QLD 2405 (1, fixed in EtOH); AM W.49291, MI QLD 2422 (1); AM W.49292, MI QLD 2422 (2, on SEM stub).

Diagnosis. Branchiae present from CH2 to last body chaetiger, straight or curved in first chaetigers, twisted from mid-body to posterior chaetigers. Parapodia biramous, with prechaetal lobe and ventral lobe; prechaetal lobe more or less symmetrical, without notch or conspicuous tip. Anal tube buccin-shaped, gradually increasing in width distally; anal tube opening wide, directed posteriorly, defining two lateral lobes; posterior margin provided with up to 20 pairs of marginal papillae of different length, 0.02–0.08 times length of anal tube; one pair of similarly shaped basal papillae; internal unpaired anal cirrus about 0.25 times length of anal tube.

Description. Based on holotype. Specimen complete, 11.5 mm long and 0.5 mm wide, with 28 chaetigers. Body slender, tapering towards anterior end ( Fig. 2 A); posterior end wide and truncated ( Figs 2 F, 3F). Prostomium conical; palpode well developed, bullet-shaped ( Figs 2 A, 3A). One dorsal eye and two lateral small dark eyes embedded in prostomium. One pair of ring-shaped nuchal organs; at least one oral tentacle protruding from pharynx ( Fig. 2 A; several tentacles in SEM paratypes: Figs 3 A, B, 4B). Segmental limits among chaetigers not defined. Branchiae present from CH 2 to last body chaetiger in left side ( CH 28), long, reaching dorsal midline; straight or curved in first chaetigers, twisted from mid-body to posterior chaetigers ( Figs 3 F, 4C, D). Parapodia biramous, with prechaetal lobe and ventral lobe on each parapodium ( Figs 2 B–E, 3C, D); dorsal cirrus not present. Prechaetal lobe more or less symmetrical, oval-shaped, without notch or conspicuous ventral tip; ventral lobe wide, becoming increasingly longer than prechaetal lobe. Lateral dark reddish eyespots anterior to parapodia on 11 chaetigers ( CH 7– CH 17); those of CH 7–9 and CH 15–17 smaller than others. Simple, long capillary chaetae in two bundles with 5–7 chaetae each ( Fig. 3 D, E); notochaetae generally longer than neurochaetae; each bundle with several additional shorter chaetae. Ventral groove deep, well defined along all body ( Figs 3 A, 4B). Anal tube long, about 3.5 times as long as wide, buccin-shaped, gradually increasing in width backwards, as long as last five chaetigers ( Figs 2 F, G, 4A, E, F). Anal tube opening wide, directed posteriorly, defining two lateral lobes, ventral incision about more than one third of tube length, dorsal incision 1/4 of tube length; posterior margin provided with about 20 pairs of short paired marginal papillae of different length, ranging from 0.02 to 0.08 times length of anal tube; one pair of basal papillae, as long as largest of others; internal unpaired anal cirrus, about 0.25 times length of anal tube.

Variation. Paratypes of Armandia buccina n. sp. bear an anal tube with similar number and distribution of papillae but in one paratype the tube is somewhat wider at distal third ( Fig. 4 A). Paratypes measure about 6.0– 13.5 mm in length and 0.5–1.0 mm in width with same number of chaetigers as holotype. Branchiae are twisted in distal half of the body; one paratype has 12 everted oral tentacles that are conical and distally pointed. Ventral incision of anal tube may well reach half of tube length.

Remarks. Armandia buccina n. sp. differs from all species of the genus because of the unique combination of features of the shape and length of the anal tube, number and shape of paired marginal papillae, length of unpaired anal cirrus and orientation of tube opening. Other species with a long anal tube (at least 3 times longer than wide) are A. leptocirris ( Grube, 1878) ( Philippines) , A. simodaensis Takahasi, 1938 ( Japan, Korea), A. longicaudata Caullery, 1944 (Java) , A. broomensis (NW Australia), A. bilobata (South Australia) and A. bifida (NE Australia). However, A. leptocirris and A. longicaudata differ from A. buccina sp. nov. in both bearing an unpaired anal cirrus that is longer than the anal tube, up to 12 marginal paired papillae and in the different shape and orientation of anal tube that is obliquely truncated; A. simodaensis has a much longer anal tube (about 1/3 of body length) that lacks marginal papillae; A. broomensis has a large unpaired anal cirrus and fewer paired marginal papillae that are as long as the anal tube; A. bilobata bears an anal tube that lacks papillae, the distal opening is wider forming two large lobes and the ventral incision is longer than half of tube length; finally, A. bifida has parapodia that are provided with bifid prechaetal lobe in anterior chaetigers.

Etymology. The epithet buccina (L.) refers to the peculiar shape of the anal tube that resembles to the distal part of the trumpet-like instrument played in ancient Roman armies.

Habitat / Distribution. Intertidal to subtidal (0–12 m) on sand all around the island and also off the Great Barrier Reef (Yonge Reef), but most specimens were collected at Casuarina beach (e.g. holotype), in front of Lizard Island Research Station ( Fig. 1 , Table 1).

Figures

FIGURE 1. Map of the study area showing collecting sites of new species described herein. Arrow in Yonge Reef symbol facing to cross-shelf site.

FIGURE 2. Armandia buccina n. sp. (holotype AM W. 49287). A, anterior end, right side, lateral view. (B – E) Parapodia, right side, lateral views: B, CH 1; C, CH 2; D, CH 4; E, CH 27. (F – G) Posterior end and anal tube: F, lateral view; G, ventrolateral view. B – E, same scale.

FIGURE 3. Armandia buccina n. sp. SEM micrographs (paratypes AM W. 49292). A, anterior end, left side, lateroventral view; B, anterior end, left side, detail; C, CH 1 – 4, left side, lateral view; D, CH 11, left side, anterolateral view; E, CH 24, left side, anterolateral view; F, posterior end, left side, lateral view.

FIGURE 4. Armandia buccina n. sp. SEM micrographs (paratypes AM W. 49292). A, anal tube, lateral view (detached from body); B, anterior end, ventrolateral view; C, posterior end, last chaetigers, ventral view; D, posterior end, last chaetigers, ventral view, detail; E, anal tube, lateral view (detached from body); F, anal tube opening, ventral incision, lateral view (detached from body).