Paradiopatra spinosa, Paxton, Hannelore & Budaeva, Nataliya, 2013

Paxton, Hannelore & Budaeva, Nataliya, 2013, Paradiopatra (Annelida: Onuphidae) from eastern Australian waters, with the description of six new species, Zootaxa 3686 (2), pp. 140-164 : 154-157

Paradiopatra spinosa n. sp.

Figures 10 , 11 ; Table 2

Material examined. Type material—Holotype (AM W36461) Bass Canyon, 38.573ºS 148.659ºE, RV Southern Surveyor, coll. D. Cummings and S. Holmes, 13 Oct 2009, 1600 m, beam trawl; SLOPE 17: 1 paratype (MV F189437); SLOPE 27: 1 paratype (MV F189438); SLOPE 55: 2 paratypes (MV F189439); 1 paratype (AM W43547); SLOPE 69: 1 paratype mounted for SEM (AM W43553.001).

Type locality. Pacific Ocean, off eastern Australia, Bass Canyon, 38.573ºS, 148.659ºE, 1600 m.

Diagnosis. Ovoid frontal lips; ceratophores without lateral projections; peristomial cirri present; first 2–3 pairs of parapodia with pseudocompound, tridentate falcigers with moderately long pointed hoods, with almost smooth shafts and appendages; very long, spinose aciculae, extending as far as falcigers; subacicular hooks equal, starting from chaetiger 12–13; branchiae absent; delicate protomandibles.

Description. All examined specimens lacking posterior ends. Length of holotype 43 mm in length, partially in tube; anterior 31 mm of worm (41 chaetigers) free of tube, median 9 mm in tube, posterior 3 mm exposed, width 1.6 mm (at chaetiger 10, excluding parapodia); paratypes ranging from 19–60 mm long (34–84 chaetigers), 0.9–1.1 mm wide. Alcohol stored specimens cream-coloured, lacking colour pattern.

Prostomium anteriorly rounded, wider than long, with paired ovoid frontal lips, separated by gap ( Fig. 10 A– C). All palps, antennae and cirri ending in very fine tips. Palps of holotype reaching chaetiger 1; lateral antennae reaching chaetiger 3; median antenna reaching chaetiger 2; palps and antennae of most paratypes in poor condition with some antennostyles overly extended or missing, giving distorted values, thus palps reaching chaetiger 1–2, lateral antennae reaching chaetiger 1–6, median antenna reaching chaetiger 1–5. Palpostyles much thicker than antennostyles ( Fig. 10 B, C). Ceratophores lacking lateral projections; lateral antennae of holotype with five rings, median with four, distal ring about twice as long as proximal ones. Ceratophores of most paratypes ranging from almost smooth to indistinctly ringed, with 3–5 rings for lateral and 3 rings for median antenna. Nuchal grooves short but wide, slightly curved. Eyes absent. Peristomium slightly shorter than first chaetiger. Peristomial cirri slender, about 2/3 length of peristomium, inserted subdistally.

First 2–3 pairs of parapodia modified, projecting anterolaterally, directed slightly ventrally. Prechaetal lobes rounded on all parapodia; postchaetal lobes long and subulate in first four chaetigers, decreasing rapidly in size, absent from chaetiger 11 (10–11). Dorsal cirri subulate and very long on anterior three chaetigers ( Fig. 11 A–C), becoming gradually shorter, present as tiny subulate structures until end of fragments. Ventral cirri subulate on first 3 (3–4) chaetigers, then shorter with blunt end on next chaetiger, before changing to ovoid ventral glandular pads ( Fig. 10 C).

Parapodia supported by 3–4 long spinose aciculae, projecting from prechaetal lobe as far as falcigers and limbate chaetae ( Fig. 11 A–C). First two pairs of parapodia with dorsal fascicle of 1–2 simple spinose limbate chaetae and ventral fascicle of 3–5 tridentate pseudocompound falcigers with moderately long pointed hoods; shafts and appendages of falcigers almost smooth ( Fig. 10 D, E). Tip of falcigers with knob-like terminal tooth and two subterminal teeth ( Fig. 11 D, E); in some cases subterminal teeth are closely spaced ( Fig. 11 F) resembling a single larger tooth, giving bidentate appearance ( Figs 10 E, 11G). Two fascicles of simple limbate chaetae starting from chaetiger 3; chaetiger 3 of holotype and most paratypes with one tridentate falciger ( Fig. 11 C), one paratype with a falciger present on left side only, and one paratype lacking falcigers on chaetiger 3 completely. From chaetiger 4 falcigers absent in all specimens. Ventral fascicle of limbate chaetae replaced by paired bidentate subacicular hooks from chaetiger 12 (12–13), hooks about equal in length and thickness ( Fig. 11 H). Pectinate chaetae slightly oblique with 17–20 teeth. Branchiae absent. Posterior end unknown. Tube cylindrical, with inner soft secreted layer and outer layer of grey mud particles.

Mandibles ( Fig. 11 I) slender, moderately sized protomandibles; paratype examined lacking calcified cutting plate. Maxillae ( Fig. 11 J) lightly sclerotized, with very slender MI. Maxillary formula (based on one paratype): MI = 1 + 1; MII = 9 + 12; MIII = 10 + 0; MIV = 6 + 6; MV = 1 + 1.

Remarks. The similarities of P. s p i n o s a to other species with two or two to three pairs of parapodia with falcigers have been discussed in the Remarks on P. longicappa . Furthermore, P. s p i n o s a can be distinguished from that and all other species in the genus by its unusually long and spinose aciculae. In most species of Paradiopatra the aciculae of the modified parapodia extend slightly or to about half the length of the falcigers from the presetal lobe. In P. spinosa , however, they extend as far as the falcigers and limbate chaetae ( Figs 10 D, 11A–C).

Etymology. The name spinosa refers to the spinose aciculae and limbate chaetae, particularly those of the modified parapodia.

Distribution. Paradiopatra spinosa n. sp., was collected in two transects: south of Sydney, NSW and off eastern Victoria in Bass Strait, in 1500–2250 m, as well as Bass Canyon, during more recent sampling, in 1600 m.

Figures

FIGURE 10. SEM images of Paradiopatra spinosa n. sp. (AM W 43553.001). A, Anterior end, dorsal view; B, same, enlarged, dorsal view; C, anterior end, ventral view; D, chaetae of parapodium 3, anterior view; E, same, enlarged, anterior view (note, lowermost falciger seemingly bidentate). Abbreviations: ac, acicula; fa, falciger; li, limbate chaeta.

FIGURE 11. Line drawings of Paradiopatra spinosa n. sp. (Holotype AM W 36461, D, E; AM W 43547, others). A, Parapodium 1, anterior view; B, parapodium 2, anterior view; C, parapodium 3, anterior view; D, E, tridentate pseudocompound falcigers from chaetiger 1; F, same from chaetiger 2; G, seemingly bidentate pseudocompound falciger from chaetiger 2; H, parapodium 16, anterior view; I, mandibles; J, maxillae.