Platynereis kau, Read, Geoffrey B., 2007

Read, Geoffrey B., 2007, Taxonomy of sympatric New Zealand species of Platynereis, with description of three new species additional to P. australis (Schmarda) (Annelida: Polychaeta: Nereididae), Zootaxa 1558, pp. 1-28 : 14-18

Platynereis kau sp. nov.

( Figs 3 , 5 C, 6E, F)

Diagnosis. Platynereis species with secondary-tooth-tipped homogomph falcigers in juveniles, with replacement ceasing when about 50 chaetigers developed; homogomph falcigers absent in adults. Male heteronereid 2-part, with 14 pre-natatory segments, pygidial papillae structure a 2-part fan of 8 large papillae. Female heteronereid 2-part, 18 pre-natatory segments, eggs white to pale golden-yellow, first 7 (6–7) dorsal cirri enlarged. Benthic atoke light orange brown anteriorly, with some brown pigment on proboscis oral ring. Segment 11 notopodial superior ligule less bluntly rounded than preceding segment.

Heteronereid material examined. Holotype. Wellington, Karaka Bay, 41° 18.34' S, 174° 49.9' E, stn Y10203, 0 m, 28.v.1970: het. male, 48 mm, coll G. Read, night light & dip net ( NIWA 3364, H-873). Paratypes. Banks Peninsula. Lyttelton Harbour, 43° 36.6' S, 172° 42.6' E:- stn GAK19580000, 0 m, 1.vi.1958: het. 2 male. Coromandel Peninsula, coast east. Whangapoua, 36° 43' S, 175° 38.4' E:- 0m 19.vi.74 ( AIM AK 10352, L3446): het. 1 male. Kaikoura Peninsula. Kaikoura, 42° 24' S, 173° 40.8' E:- 0m, 19.viii.1961 (UCANTK K079A): het. 3 male. Marlborough Sounds. Elie Bay, 41° 7.8' S, 173° 58.8' E:- stn Y10288, 0 m, 4.v.1973: het. 1 female. Tory Channel, 41° 14.4' S, 174° 13.2' E:- stn Y10245, 0 m, 30.viii.1972: het. 3 male, 1 female. Nelson, coast. Port Nelson, 41° 15.6' S, 173° 15.6' E:- stn GAK19410900, 0 m, 1.ix.1951: het. 1 female. Northland, coast east. Matapouri Bay, 35° 33.6' S, 174° 30' E:- stn Y10291, 0 m, 3.ix.1978: het. 1 male. Tutukaka Harbour, 35° 36.6' S, 174° 32.4' E:- stn Y10290, 0 m, 13.vii.1975: het. 1 male. Otago Harbour. Quarantine Island, 45° 49.8' S, 170° 37.2' E:- stn GAK19530606, 1 m, 6.vi.1953: het. 1 male. Three Kings Islands. NW Bay, Great King I., 34° 9.6' S, 172° 4.2' E:- stn Y10292, 0 m, 4.i.1976: het. 14 male, 15 female. Wellington Harbour. Evans Bay, 41° 18.6' S, 174° 48' E:- stn Y10262, 0 m, 27.iii.1973: het. 3 male, 3 female. Greta Point (Evans Bay), 41° 18.6' S, 174° 48' E:- stn Y10152, 0 m, 24.viii.2003: het. 2 male, 2 female. Karaka Bay, 41° 18.34' S, 174° 49.9' E:- stn Y10202, 0 m, 25.v.1970: het. 1 male; stn Y10203, 0 m, 28.v.1970: het. 9 male, 2 female; stn Y10204, 0 m, 30.v.1970: het. 1 male; stn Y10206, 0 m, 24.vi.1970: het. 19 male; stn Y10207, 0 m, 27.vi.1970: het. 4 male, 1 female; stn Y10208, 0 m, 27.vii.1970: het. 6 male, 5 female; stn Y10209, 0 m, 25.viii.1970: het. 1 female; stn Y10235, 0 m, 4.vi.1972: het. 4 male, 3 female; stn Y10236, 0 m, 7.vi.1972: het. 1 male; stn Y10238, 0 m, 3.vii.1972: het. 2 male. Kau Bay, 41° 16.8' S, 174° 49.2' E:- stn Y10274, 0 m, 7.v.1975: het. 4 male, 3 female. Mahanga Bay, 41° 17.4' S, 174° 49.8' E:- stn Y10241, 0 m, 3.viii.1972: het. 2 female; stn Y10242, 0 m, 10.viii.1972: het. 3 female; stn Y10243, 0 m, 14.viii.1972: het. 1 male; stn Y10254, 0 m, 10.xi.1972: het. 1 male; stn Y10261, 0 m, 27.ii.1973: het. 5 male; stn Y10264, 0 m, 30.iv.1973: het. 5 male, 1 female; stn Y10268, 0 m, 27.vii.1973: het. 5 male, 6 female; stn Y10269, 0 m, 24.viii.1973: het. 1 male. Shark Bay (Evans Bay), 41° 18.6' S, 174° 48' E:- stn Y10151, 0 m, 18.viii.2003: het. 1 female. Wellington, coast south. Island Bay, 41° 21.02' S, 174° 46.11' E:- stn Y10253, 0 m, 6.xi.1972: het. 1 male; stn Y10278, 0 m, 18.viii.1976: het. 4 male, 8 female; stn Y10283, 0 m, 4.x.1977: het. 1 female; stn Y10284, 0 m, 6.x.1977: het. 4 male, 3 female. Wellington, coast west. Round Point, nr Titahi Bay, 41° 6.5' S, 174° 49' E:- stn Y10279, 0 m, 16.xi.1976: het. 12 male, 16 female. Whakaari (White) Island. Whakaari Island, 37° 31' S, 177° 11' E:- 0m, 24.ii.1957 ( MONZ unregistered): het. 2 male.

Non-type other material examined. Wellington Harbour. Kau Point, 41° 16.8' S, 174° 49.2' E:- stn Y10303, 3 m, 23.vi.1971: 9 atoke; stn Y10309, 3 m, 11.v.1973: 5 atoke. Mahanga Bay, 41° 17.4' S, 174° 49.8' E:- stn Y10299, 4 m, 25.xi.1970: 9 atoke; stn Y10300, 9 m, 8.xii.1970: 45 atoke. Ward Island, 41° 18' S, 174° 51.996' E:- stn Y10296, 5 m, 14.v.1970: 39 atoke; stn Y10301, 5 m, 15.iii.1971: 21 atoke; stn Y10310, 5 m, 14.vii.1973: 3 atoke; stn Y10311, 5 m, 17.vii.1973: 9 atoke. Wellington, coast south, Island Bay, 41° 21.02' S, 174° 46.11' E:- stn Y10317, 8 m, 16.vii.1975: 8 atoke. Wellington, coast west, Round Point, offshore, 41° 6.5' S, 174° 49' E:- stn Y10316, 10 m, 12.vii.1975: 4 atoke; stn Y10323, m, 3.vii.1976: 12 atoke.

Size and shape. Atoke length up to 160 mm for 120 segments. Male heteronereid pre-natatory region widest midway along and narrowing before junction of body regions. Posterior natatory region strongly tapered, but not as pronounced as in P. mahanga . Wellington region specimens mean length 34 mm, range 11–57 mm (std dev. 10 mm, n 36). Female heteronereid body almost uniform in width. Wellington region specimens mean length 31 mm, range 18–46 mm (std dev. 11 mm, n 10).

Atoke description. Head region, parapodia and chaetae as in P. australis , paragnaths and proboscis as in P. mahanga . Segment 11 notopodial superior ligule transitional, slightly conical rather than bluntly rounded.

Atoke live colouration. Anterior dorsal body behind head with light orange brown pigmentation, becoming more orange during heteronereid transformation. Oral ring of proboscis with some brown pigment, less developed than in P. australis . Posterior pigmentation as in P. australis .

Male heteronereid description. A two-part heteronereid. Enlarged eyes dark red and head bent down when proboscis retracted. Pre-natatory region unvaryingly with 14 segments (n 76), with division between regions very sharp without transitional segments. Anterior first 7 dorsal cirri and 4 ventral cirri enlarged, without variation ( Fig. 3 ). Chaetiger 8–14 parapodia unmodified. Anterior natatory parapodia and chaetae as in P. australis ; posterior parapodia shaped and orientated towards dorsal surface as in P. mahanga (see Fig. 2C). Pygidial structure a horizontal fan with 8 papillae in two equal branches ( Fig. 6 F), identical to P. mahanga males (Fig. 2B). Gravid male in life colouration as in P. australis heteronereid males except anterior body yellow-orange tinted with lines of orange-red surface pigment present, and additionally some golden-yellow flecks of pigment on posterior dorsal cirri bases. Holotype male as above, 48 mm for 102 segments, with 14 pre-natatory segments, proboscis everted, paragnaths typical, except lines somewhat thickened, segments 5–10 with glandular blunt anterior superior notopodial ligules, segment 11 ligule transitional, slightly conical.

Female heteronereid description. A two-part heteronereid. Eyes and head ( Fig. 6 E) as in male. Pre-natatory region with 18 segments, without variation (n 27). Anterior first 7 (6–7) dorsal cirri enlarged (2 with seventh cirrus only partly metamorphosed, 1 with 6 enlarged dorsal cirri only, n 17). Always 4 enlarged ventral cirri. Parapodia of chaetigers 8 to 18 unmodified.

Anterior natatory parapodia as in P. australis females. Distinct unmodified posterior region absent, but development of epitokal lamellae progressively reduced until last few segments almost completely unmodified as in P. mahanga females (see Fig. 2D). Chaetae often absent in parapodia of these segments, except occasionally for a few natatory chaetae in both rami, or a few neuropodial spinigers and a heterogomph falciger. Pygidium unmodified except anal cirri absent. Eggs 170 to 190 µm in diameter. Gravid female in life colouration white to pale golden yellow due to colour of the eggs, except far anterior where atoke colouration can still be apparent ( Fig. 6 E). Dorsal blood vessel prominent as in males and spent females similar in colouration to spent males.

FIGURE 4. Platynereis karaka sp. nov., A, composite anterior dorsal body of heteronereid, male parapodia on left, female on right, tentacular cirri and chaetae omitted for clarity; B, heteronereid male 4th parapodium; C, heteronereid male natatory 5th pre-pygidial parapodium; D, heteronereid male pygidial papillae structure, dorsal view; E, heteronereid male midline papillae, in close lateral view and as body outline; F, heteronereid female natatory 5th pre-pygidial parapodium. Parapodia viewed from anterior. Scale bar: 1 mm A, D; 0.5 mm B, C, E (3 mm E outline), F.

Juvenile chaetation and colour. Homogomph notopodial falcigers developing at about 9-chaetiger stage, with morphology as in P. australis . Single homogomph falciger present posteriorly in early juveniles beginning from chaetiger 8 at 9–12 chaetiger stage, 8 to 14th at 16-chaetiger stage, but lacking in specimens of 50 or more chaetigers obtained from washings of Macrocystis pyrifera fronds.

Juvenile pigmentation pattern of dorsal white surface pigment on the head, on pygidium, and along midline on either side of dorsal blood vessel, and large elongate lateral blotches of red pigment on almost all segments ( Fig. 5 C). White midline pigment intermittent anteriorly, posteriorly usually in more or less rectangular blocks. Pattern apparent until about 50 chaetigers have developed when white-head pigment gradually lost and red pigment spots become smaller. White middorsal pigment then taking on linked-chain pattern, and diffuse orange-brown anterior colouration of adult present. Region of anterior thickened ligules present.

Reproduction. At Wellington P. kau swarming occurred over an extended summer to spring period, February–November, with maximum abundance late autumn to late winter (May–August). Spawning occurred with tight-circle swimming by males as in P. mahanga .

Habitat. Subtidal only, common in the holdfasts of large algae, especially Macrocystis pyrifera . A tough detritus and secretion tube is formed.

Distribution. New Zealand mainland islands, Three Kings Islands, Whakaari (White) Island.

Etymology. The epithet kau is a noun in apposition.

Remarks. There are no prior reports in the literature of heteronereids with the morphology of P. k a u. It differs markedly from P. australis in heteronereid morphology, particularly in male pygidial structure as described, and as an atoke less definitively in colour pattern and minor morphological differences.

P. kau heteronereids were larger than P. k a r a k a and smaller than P. australis , but were not significantly different in length between sexes or in relation to P. mahanga . Male heteronereids were very similar to those of P. k a r a k a apart from the difference in number of pre-natatory segments. Mean length of the pre-natatory region of males was only slightly less than in P. mahanga although of 4 fewer segments ( Table 7 ). Pre-natatory segments appear to be slightly longer in P. k a u. Females usually had 4 more pre-natatory segments than males.

P.seg, = number of pre-natatory segments; P.length = mean length (mm) of pre-natatory region; P:T ratio = mean ratio of pre-natatory length to total length.

Figures

FIGURE 3. Platynereis kau sp. nov., composite anterior dorsal body of heteronereid, male parapodia on left, female on right, tentacular cirri and chaetae omitted for clarity. Scale bar 1 mm.

FIGURE 5. Platynereis juvenile dorsal pigmentation pattern, A – C, P. australis, P. mahanga sp. nov., P. k a u sp. nov. respectively. Scale bar 0.5 mm.

FIGURE 6. A, Platynereis australis female anterior dorsal; B, P. australis male anterior lateral; C, P. australis juvenile distal tip of homogomph falciger; D, P. mahanga sp. nov. female anterior dorsal; E, P. k a u sp. nov. female anterior dorso-lateral; F, P. k a u sp. nov. male dorsal pygidium; G, P. australis male pygidium in left lateral view; H, P. karaka sp. nov. male anterior lateral; I, P. karaka sp. nov. male dorsal midline papillae (anterior to top). Images A, B, D – I are photographs of live heteronereid specimens captured at night. Scale bar: 1 mm A, B, D, E, G; 0.5 mm F, H; 0.2 mm I; 5 μm C.

Tables

TABLE 7. Platynereis male heteronereids ratio of pre-natatory region length to total length.

Species	P.seg.	P.length	std.dev.	P:T ratio	std.dev	P:T range	n
Platynereis australis	27	14.7	4.6	1:3.28	0.41	2.72–4.28	18
Platynereis mahanga	18	9.7	2.9	1:3.49	0.47	2.8 –4.43	15
Platynereis kau	14	9.4	2.8	1:3.66	0.47	3.1–4.75	13
Platynereis karaka	14	5.5	1.8	1:4.77	0.96	3.25–6.67	11