Polycirrus culcita, Nogueira, João Miguel Matos, Hutchings, Pat & Carrerette, Orlemir, 2015

Nogueira, João Miguel Matos, Hutchings, Pat & Carrerette, Orlemir, 2015, Polycirridae (Annelida, Terebelliformia) from Lizard Island, Great Barrier Reef, Australia, Zootaxa 4019 (1), pp. 437-483 : 470-472

Polycirrus culcita n. sp.

( Fig. 20 )

Type material. Holotype: AM W.47643, Watsons Bay, 100 m of Chinamans Ridge, soft sediments with patchy seagrasses, 9 m, coll. Jones & Short, hand corer, 13 Oct 1978, incomplete, in good state of preservation, an anterior fragment with 20 segments, ~ 9 mm long, 1.3 mm maximum width, at end of fragment.

Comparative material examined. Holotype of Polycirrus parvus , AM W.199628. Paratypes of Polycirrus parvus , AM W.199630 and AM W.199631. Paratypes of Polycirrus tesselatus , AM W.199468, AM W.199469.

Description. Transverse prostomium attached to dorsal surface of upper lip; basal part as thick, horseshoeshaped crest, distal part extending along upper lip and terminating near anterior margin ( Fig. 20 A–G). Few buccal tentacles remaining, all almost uniformly cylindrical, relatively thin and elongate ( Fig. 20 A–G). Peristomium forming lips; large upper lip, convoluted, longer than wide; lower lip divided in two regions, inner region buttonlike, outer region cushion-like, rounded and deeply corrugated, extending far from oral area, but not covering entire ventrum ( Fig. 20 A–G). Segment 1 only visible dorsally, relatively large, covered by expanded prostomium and lower lip laterally and ventrally, respectively; segment 2 terminating ventro-laterally, also covered by expanded lower lip ( Fig. 20 A–G). Smooth, swollen, clearly defined ventro-lateral pads with transverse corrugations, extending until segment 9, then body distinctly swollen, with poorly defined segmentation and fragile body wall ( Fig. 20 A–D, F–G). Notopodia extending for 10 segments, until segment 12; elongate, bilobed notopodia, postchaetal lobe longer ( Fig. 20 A–G). Broadly-winged notochaetae sensu Fitzhugh et al. (2015) in both rows, wings only at tips, striated, conspicuous under light microscopy ( Fig. 20 H–J). Neuropodia beginning from segment 15, third after termination of notopodia, first two pairs almost sessile, then as short pinnules; uncini with elongate neck, otherwise as type 1, crest with single elongate and sharp tooth per row in first two rows above main fang, with additional row of shorter, irregularly sized teeth at base, medial tooth larger, and conspicuous dorsal button ( Fig. 20 K–L). Nephridial and genital papillae inconspicuous throughout, at least under stereomicroscopy ( Fig. 20 A–G). Pygidium unknown.

Remarks. The holotype is the only known specimen of P. culcita n. sp., it is incomplete and ~ 1 cm long, with the distal part of prostomium extending until near the anterior margin of the upper lip; rounded, cushion-like lower lip; clearly defined, swollen ventro-lateral pads, smooth except for transverse corrugations; 10 pairs of notopodia, on segments 3–12, with longer post-chaetal lobe and bearing broadly-winged chaetae in both rows; neuropodia beginning on the third segment after the termination of notopodia, segment 15, and bearing uncini with elongate neck, but otherwise type 1; and with inconspicuous or absent nephridial and genital papillae.

Similarly to Polycirrus cruciformis n. sp., P. culcita n. sp. is a species with few pairs of notopodia and neuropodia beginning shortly after the termination of notopodia. So, the species morphologically most similar to P. culcita n. sp. are the same as those already discussed for P. c r u c i f or m i s n. sp., with the addition of P. mexicanus Rioja, 1947 , since P. culcita n. sp. has two more pairs of notopodia than P. cr u c i f or m i s. Polycirrus cruciformis n. sp. and P. culcita n. sp. differ because the former species has the distal part of prostomium restricted to the base of the upper lip; button-like and mid-ventral lower lip; 8 pairs of notopodia, with evenly sized lobes; neuropodia beginning from the first segment after the termination of notopodia, with typical type 1 uncini, with short neck; and nephridial and genital papillae present until segment 9. The holotype of P. culcita n. sp., on the other hand, has the distal part of prostomium extending along the upper lip until near the anterior margin of the lip; cushion-like, rounded lower lip, extending across ventrum and reaching segment 3; 10 pairs of notopodia, extending to segment 12 and with longer post-chaetal lobe; neuropodia beginning on the third segment after the termination of notopodia, segment 15, with type 1 uncini with elongate neck; and nephridial and genital papillae are inconspicuous or absent.

Polycirrus antarcticus has the distal part of prostomium restricted to the base of the upper lip; large, rectangular lower lip extending across ventrum; 11 pairs of notopodia, until segment 13, with evenly sized lobes; and type 1 uncini with short neck ( Glasby & Hutchings 2014).

Members of P. medusa differ from the holotype of P. culcita n. sp., as they have 12 pairs of notopodia, extending until segment 14 and bearing pinnate chaetae in anterior row of notochaetae; and nephridial and genital papillae are present until segment 8 ( Glasby & Hutchings 2014).

Polycirrus mexicanus is a poorly known species, for which type material could not be located by Hutchings & Glasby (2014), thus, only the original description, missing several important characters, is available. According to Rioja (1947), members of P. mexicanus have 14–18 pairs of notopodia, with pinnate chaetae in posterior row; and uncini with similar morphology to those of P. culcita n. sp., but with a single tooth above main, while in our specimen there are three rows of secondary teeth.

Members of P. papillosus have tessellated, highly papillated ventro-lateral pads; 11–14 pairs of notopodia, with pinnate chaetae in anterior row of notochaetae; and neuropodia beginning from the second abdominal segment, with type 1 uncini with short neck ( Carrerette & Nogueira 2013).

Another Australian species, P. parvus described from north-west Australia from depths of 40–80 m, is separated from the holotype of P. cu l c i t a n. sp. because its members have neuropodia beginning from the second segment after notopodia terminate ( Glasby & Hutchings 2014). They also differ in the relative proportions of the upper lip, in P. parvus the anterior extension of the lip is much shorter than in Polycirrus culcita n. sp., where the upper lip is almost three times longer than wide.

Polycirrus paucidens is different from the holotype of P. culcita n. sp. because P. paucidens has 7–9 pairs of notopodia; neuropodia beginning slightly more posteriorly, bearing intermediate uncini between types 1 and 2 ( Glasby & Hutchings 2014) but with a morphology different from those of P. culcita n. sp.

Members of P. tesselatus Hutchings & Glasby, 1986 differ from P. culcita n. sp. in having tessellated ventrolateral pads and nephridial and genital papillae extending to segment 10 ( Glasby & Hutchings 2014). The paratypes of P. tesselatus , while having tessellated ventral pads they lack a distinct ventral groove, which is very conspicuous in P. culcita n. sp.

Finally, P. variabilis Hutchings & Glasby, 1986, known from material from the Lizard Island region, differs from the holotype of P. culcita n. sp. because members of this species have larger lower lip, rectangular; tessellated ventro-lateral pads; narrowly-winged, acicular notochaetae; and type 1 uncini with short neck and 1–2 rows of secondary teeth (Glasby & Hutchings 2014).

Etymology. The specific name “ culcita ” refers to the expanded lower lip in this species and derives from the Latin.

Habitat. Soft sediments with patchy seagrasses, 9 m.

Type locality. 100 m of Chinamans Ridge, 14˚40’S, 145˚28’E, Watsons Bay, Lizard Island, Great Barrier Reef, Australia.

Distribution. Known only from the Lizard Island region.

Figures

FIGURE 20. Polycirrus culcita n. sp., holotype AM W. 47643. A – B. Entire incomplete worm, dorsal and ventral views, respectively; C – D. Anterior end, dorsal and ventral views, respectively; E – G. Close ups of the anterior end, dorsal and two ventral views, in progressively higher magnifications; H. Notochaetae, segment 5; I – J. Close up of the tips of notochaetae from anterior and posterior rows, respectively, segment 5; K – L. Uncini, segments 16 and 20, respectively. Numbers refer to segments. Abbreviations: i = inner region of lower lip, ll = lower lip, o = outer region of lower lip, P = basal part of prostomium, ul = upper lip, * = distal part of prostomium. Scale bars: A – B = 500 µm, C = 300 µm, D – F = 200 µm, G = 100 µm, H = 30 µm, I – J = 10 µm, K – L = 7 µm.