Platynereis australis ( Schmarda, 1861 )

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 : 5-10

Platynereis australis ( Schmarda, 1861)

(Figs 1, 5A, 6A–C, G)

Heteronereis australis Schmarda 1861:101 –102, in-text un-numbered fig., pl.31, fig. 242, Auckland Harbour. Platynereis australis .— Knox 1960:124, Fig.182–184, [In part] Chatham Island.

Diagnosis. Secondary-tooth-tipped homogomph falcigers in juveniles, with replacement ceasing when about 50 chaetigers developed; homogomph falcigers absent in adults. Male heteronereid 2-part, 27 (26–28) prenatatory segments, pygidial papillae structure a complex rosette. Female heteronereid 3-part, 33 (32–34) prenatatory segments, eggs white to pale golden-yellow. Benthic atoke dark green anteriorly with some brown pigment on blunt thickened lobes of chaetiger 5–11, on prostomium, and oral proboscis ring.

Heteronereid material examined. Auckland Harbour. Devonport 36° 49.8' S, 174° 47.4' E:- stn Y10271, 0 m, 15.ix.1974: het. 1 female; stn Y10272, 0 m, 16.ix.1974: het. 1 male. Banks Peninsula. Menzies Bay, 43° 38.4' S, 172° 57.6' E:- stn GAK19531100, 0 m, 1.xi.1953: het. 1 female; stn GAK19580501, 0 m, 1.v.1958: het. 1 male. Chatham Island. Port Hutt, 43° 48.12' S, 176° 42.50' W, 18.ix.50 ( MONZ unregistered): het. 14 male. Kaikoura Peninsula. Kaikoura, 42° 24' S, 173° 40.8' E:- 19.viii.1961 (UCANTK K079A): het. 3 male, 2 female. Marlborough Sounds. Elie Bay, 41° 7.8' S, 173° 58.8' E:- stn Y10244, 0 m, 29.viii.1972: het. 10 male, 10 female; stn Y10251, 0 m, 1.xi.1972: het. 6 male, 5 female; stn Y10257, 0 m, 27.xi.1972: het. 19 male; stn Y10288, 0 m, 4.v.1973: het. 2 male. Kenepuru Sound, 41° 12' S, 173° 58.8' E:- stn Y10220, 0 m, 22.vi.1971: het. 3 male. Tory Channel, 41° 14.4' S, 174° 13.2' E:- stn Y10245, 0 m, 30.viii.1972: het. 5 male, 6 female. Otago Harbour. Portobello wharf, 45° 49.8' S, 170° 39' E:- stn GAK19570824, 0 m, 24.viii.1957: het. 3 male, 1 female. Otago Harbour unspecified, 21.i.1957 ( MONZ unregistered): het. 2 female. Wellington Harbour. Evans Bay, 41° 18.6' S, 174° 48' E:- stn Y10259, 0 m, 4.xii.1972: het. 2 male, 3 female. Greta Point (Evans Bay), 41° 18.6' S, 174° 48' E:- stn Y10152, 0 m, 24.viii.2003: het. 1 male; stn Y10165, 0 m, 14.i.2004: het. 1 male. Karaka Bay, 41° 18.34' S, 174° 49.9' E:- stn Y10221, 0 m, 30.vi.1971: het. 1 male, 1 female. stn Y10226, 0 m, 13.x.1971: het. 1 female; stn Y10228, 0 m, 9.xii.1971: het. 1 female; stn Y10229, 0 m, 8.i.1972: het. 1 female; stn Y10239, 0 m, 18.vii.1972: het. 1 male; stn Y10289, 0 m, 8.ix.1975: het. 4 male, 1 female. Kau Bay, 41° 16.8' S, 174° 49.2' E:- stn Y10222, 0 m, 15.vii.1971: het. 1 male; stn Y10274, 0 m, 7.v.1975: het. 1 female. Mahanga Bay, 41° 17.4' S, 174° 49.8' E:- stn Y10241, 0 m, 3.viii.1972: het. 2 male; stn Y10242, 0 m, 10.viii.1972: het. 41 male, 31 female; stn Y10243, 0 m, 14.viii.1972: het. 11 male, 5 female; stn Y10246, 0 m, 11.ix.1972: het. 13 male, 3 female; stn Y10247, 0 m, 28.ix.1972: het. 8 male, 5 female; stn Y10254, 0 m, 10.xi.1972: het. 5 male, 1 female; stn Y10258, 0 m, 28.xi.1972: het. 1 male; stn Y10261, 0 m, 27.ii.1973: het. 2 male, 1 female; stn Y10263, 0 m, 5.iv.1973: het. 1 male, 1 female; stn Y10268, 0 m, 27.vii.1973: het. 12 male, 2 female; stn Y10269, 0 m, 24.viii.1973: het. 3 male, 1 female; stn Y10275, 0 m, 3.ix.1975: het. 11 male, 3 female. Shark Bay (Evans Bay), 41° 18.6' S, 174° 48' E;-, stn Y10151, 0 m, 18.viii.2003: het. 1 male, 2 female; stn Y10153, 0 m, 25.viii.2003: het. 1 female; stn Y10156, 0 m, 22.ix.2003: het. 2 female; stn Y10156, 0 m, 22.ix.2003: het. 8 male. Somes Island, 41° 15.198' S, 174° 52.2' E:- stn Y10200, 0 m, 26.vi.1967: het. 3 male, 4 female; stn Y10201, 0 m, 27.vii.1967: het. 1 female. Wellington, coast south, Island Bay, 41° 21.02' S, 174° 46.11' E:- stn Y10250, 0 m, 1.xi.1972: het. 2 male, 1 female; stn Y10252, 0 m, 2.xi.1972: het. 2 male; stn Y10253, 0 m, 6.xi.1972: het. 1 male; stn Y10278, 0 m, 18.viii.1976: het. 10 male, 8 female; stn Y10284, 0 m, 6.x.1977: het. 6 male, 2 female; stn Y10285, 0 m, 10.x.1977: het. 5 male, 1 female. Wellington, coast west, Round Point, near Titahi Bay, 41° 6.5' S, 174° 49' E:- stn Y10279, 0 m, 16.xi.1976: het. 1 female.

Other material examined. Auckland, coast east, Howick Beach, 36° 53.4' S, 174° 56.4' E:- stn Y10314, 0 m, 17.ix.1974: 8 atoke. Chatham Island, Kaingaroa, 43° 44.2' S, 183° 43.9' E:- stn Z8619, 0 m, 10.ii.1997: 11 atoke. Manukau Harbour, Cornwallis Beach, 37° 0' S, 174° 36' E:- stn Y10326, 0 m, 19.ii.1979: 1 atoke. Wairarapa, coast east, Riversdale Beach south, 41° 5.4' S, 176° 4.2' E:- stn Y10321, 0 m, 13.xii.1975: 2 atoke. Wellington Harbour. Evans Bay, 41° 18.6' S, 174° 48' E:- stn Y10307, 0 m, 9.iv.1973: 1 atoke; stn Y10312, 0 m, 1.viii.1973: 2 atoke; stn Y10306, 0 m, 9.x.1972: het. 3 male; stn Y10313, 0 m, 22.viii.1974: 6 atoke. Kaiwharawhara, 41° 15.6' S, 174° 47.4' E:- stn Y10325, 2 m, 26.iii.1977: 5 atoke. Karaka Bay, 41° 18.34’ S, 174° 49.9’ E:- stn Y10302, 0 m, 21.vi.1971: 2 atoke; stn Y10315, 0 m, 30.iv.1975: 1 atoke; stn Y10318, 0 m, 8.ix.1975: 7 atoke. Mahanga Bay, 41° 17.4' S, 174° 49.8' E:- stn Y10275, 0 m, 3.ix.1975: 3 atoke. Wellington, coast south, Island Bay, 41° 21.02' S, 174° 46.11' E:- stn Y10317, 8 m, 16.vii.1975: 2 atoke; stn Y10319, 0 m, 23.x.1975: 1 atoke. Wellington, coast west, Plimmerton north, 41° 4.8' S, 174° 51' E:- stn Y10320, 0 m, 11.xi.1975: 2 atoke.

Size and shape. Atoke up to 200 mm length, for 160 segments. Male heteronereid body almost uniform in width, tapering slightly posteriorly, with anterior pre-natatory region almost as wide as natatory region. New Zealand mainland specimens mean length 40 mm, range 23–67 mm (std dev. 3 mm, n 49). Chatham Islands specimens mean length 52 mm, range 41–68 mm (std dev. 8 mm, n 14). Female heteronereid body almost uniform width overall as in male, mean length (Wellington specimens) 46 mm, range 23–86 mm (std dev. 10 mm, n 36).

Atoke description. Head region with prostomium longer than broad, antennae and palps about equal in length to prostomium. Palpostyles elongate, tentacular cirri long and thin, reaching to about the 12th chaetigerous segment. Two pairs of small, dark brown eyes, anterior pair more laterally placed. Middorsal nuchal cushion present, projecting forward slightly on to head from apodous peristomial segment. Proboscis maxillary ring area IV with the most prominent paragnaths, comprising up to 10 curved diagonal lines, longest towards midline, but usually innermost ones incomplete in the middle (Fig. 1B). Area III with up to five transverse paragnath groups with centre group always largest in size and most clearly developed; up to six lines of pectinate bars in each group, furthest lateral groups reduced, faint, or even sometimes missing. Area VI a small group of up to four short, curved, transverse lines (Fig. 1A). Area VII–VIII with five groups of up to four transverse lines, but more often only three or four groups as outer ones fainter and often missing. Maxillary ring of the proboscis often expands in width anteriorly (Fig. 1C), Jaws golden yellow to dark brown in colour, with about seven teeth.

Parapodia biramous, except subbiramous on chaetigers 1–2 with one notopodial ligule. Parapodial ligules slim cones except those thickened and rounded on chaetigers 5 to 11 (Fig. 1E). Chaetiger 12 superior notopodial ligule conical, not rounded; inferior ligule rounded. Chaetiger 1–5 neuroacicular postchaetal lobe longer than prechaetal lobe (Fig. 1E). From mid-body whole neuroacicular lobe reduced in size, superior notopodial ligule lengthened and base enlarged as a characteristic glandular structure (Fig. 1F). Dorsal cirrus very long posteriorly and always longer than superior notopodial ligule, except in the first few chaetigers. Notochaetae homogomph spinigers up to 18 per fascicle in midbody, and reduced to 2 or 3 posteriorly. Homogomph bifid notopodial falcigers absent in adults, except sometimes occurring in regenerating posterior segments, present in juvenile worms up to about 50-chaetiger stage, 1 per fascicle; falciger distal tip with rounded secondary tooth, subdistal main tooth tip also rounded, with connecting tendon from tip (Fig.1G, 6C). Neurochaetae include homogomph and heterogomph spinigers and heterogomph falcigers. Supra-acicular spinigers homogomph, up to 8 per fascicle, infra-acicular spinigers heterogomph, 2 to 3 per fascicle. Heterogomph falcigers present from chaetiger 5 onwards, up to 4 above acicula and up to 15 below. Anterior falcigers ornamented on blade with fine hairs (Fig. 1H), mid-body falcigers with hairs reduced, posterior falcigers thicker, usually lacking hairs (Fig. 1I). Posteriorly numbers of neurochaetae reduced.

Atoke live colouration. Greenish brown dorsal body on anterior segments. Head with some dark pigment, oral proboscis ring with brown pigmentation. Thickened, pale-tipped, parapodial ligules of chaetigers 5 to 11 with basal ring of brown pigmentation. Glandular bases of notopodial ligules in posterior segments pigmented white. From midbody dorsal midline, yellow-white pigmentation present in characteristic nereidid ‘chain-link’ pattern with most pigment at segment boundaries. Dorsal cirri bases may have flecks of yellow pigment. Head, parapodial (chaetigers 5–11), and proboscis pigmentation retained under formalin preservation, but may be lost in alcohol.

FIGURE 1. Platynereis australis , A–B, atoke proboscis in dorsal and ventral view; C, composite anterior dorsal body of heteronereid, male parapodia on left, female on right, tentacular cirri and chaetae omitted for clarity; D, atoke 4th parapodium; E, atoke 10th parapodium; F, atoke posterior parapodium; G, juvenile homogomph notopodial falciger; H, atoke anterior neuropodial falciger; I, atoke posterior neuropodial falciger; J, natatory chaeta; K, heteronereid male 4th parapodium; L, heteronereid male natatory 20th parapodium; M, heteronereid female natatory 20th parapodium; N, heteronereid male pygidial papillae structure, dorsal view; O–P heteronereid male and female natatory 5th pre-pygidial parapodia. All parapodia viewed from anterior. Scale bar: 1 mm A–C, L–M, N; 0.5 mm D–F, K, O–P; 0.1 mm J; 0.03 mm H–I, 0.01 mm G.

Male heteronereid description. A two-part heteronereid. Enlarged eyes dark red and head carried bent down when proboscis retracted (Fig. 1C (left side), 6B). Pre-natatory region with 27 (26–28) segments, with variation in Wellington region specimens as follows: 27 anterior segments in 42%, 26 anterior segments in 22%, and 28 anterior segments in 10% of individuals ( Table 1 ). Anterior 7 dorsal and 4 ventral cirri enlarged in males except for a short distal portion (Fig. 1C, 6B). No variation in these numbers found. Chaetigers 8 to 27 (mean) with parapodia unmodified from atoke morphology (see Fig. 1E).

Male natatory parapodia (Fig. 1L) from chaetiger 28 (27–29) to end of body. Notopodial ligules flattened, neuropodial ligule absent. Additional thin, flat, heteronereid lamellae as follows: large oval, postchaetal neuropodial lamella overlapping with smaller foliaceous inferior notopodial lamella; rounded lamellae at bases of dorsal and ventral cirri; narrow lamella-like lobes above ventral cirrus, projecting below neuropodial chaetal lobe. Dorsal cirri with about 10 graded papillae on antero-ventral edge, largest distally, reduced in size on posterior segments. Atokous chaetae all replaced by densely packed overlapping natatory chaetae, each with flat paddle-like blade finely serrated on lower edge (Fig. 1J). Posterior natatory region parapodia small with reduced lamellae (Fig. 1O).

* Wellington Harbour and regional coasts, Marlborough Sounds. ** t = transitional segment.

Pygidial papilla structure a complex rosette as follows: almost complete circle of two to three rows of sometimes branched papillae obscuring anal opening apart from ventral gap; pair of ventral lobes bearing long sometimes-branched papillae extending out, below and posterior to anal opening (Fig. 1N, 6G). Ventral papilla structure may be weakly developed, or regenerating after damage.

Gravid male in-life colouration white tinged with brownish green in pre-natatory region, and with white middorsal strip in natatory region (about a quarter of total body width) ( Fig. 6 B). Natatory region parapodia pink due to extensive surface vascularization. Pygidial papillae white. Middorsal blood vessel red, prominent along surface in pre-natatory region, just below surface in natatory region. Spent males showing deeper anterior green colour, as present in atokes.

Female heteronereid description. Three-part heteronereid but development of posterior region variable. Head and eyes as in male. Pre-natatory region with 32, 33, or 34 segments (22%, 24% and 17% of sample population respectively, range 31–36 ( Table 2 )). Pre-natatory region parapodia as in male heteronereids except first 6 anterior dorsal cirri enlarged (Fig 1C right, 6A), or 7th cirrus transitional (34%) or completely enlarged (17%), or very rarely fewer than 6 enlarged cirri ( Table 3 ). First 4 anterior ventral cirri enlarged. Natatory parapodia with lamellae similar to but smaller than in males and with dorsal cirri papillae lacking (Fig. 1M). Posterior unmodified body region variable, usually 20 to 30 segments long, not prominently separated from natatory region. Posterior region parapodia as in atoke, except lacking notochaetae (Fig. 1P). Neurochaetae homogomph and heterogomph spinigers and heterogomph falcigers. Pygidium as in atoke except lacking anal cirri. Eggs 170–190 µm in diameter. Gravid female in life colouration overall white to pale golden yellow over most of body due to colour of eggs, except anterior where atoke colouration can still be apparent ( Fig. 6A ). Dorsal blood vessel prominent as in males, and spent females similar in colouration to spent males.

Juvenile chaetation and colour. Homogomph bifid notopodial falcigers (Fig. 1G, 6C) developing at about 10-chaetiger stage. Single homogomph falciger per segment present posteriorly in laboratory reared and wild juveniles (identified as P. australis from pigment and habitat), beginning from chaetiger 8 or 9 at 18-chaetiger stage, from 10th at 21-chaetiger wild (W), 15th at 30-chaetiger (W), 21st at 35-chaetiger (W), 21st at 37-chaetiger, 35th at 40-chaetiger, 37th at 50-chaetiger, 47th at 55-chaetiger (W), and lost completely in some juveniles at 40-chaetiger stage onwards.

Juvenile pigmentation pattern of dorsal white surface pigment on head, pygidium, and along midline on either side of dorsal blood vessel, and lateral dots of red pigment on anterior 5 to 7 segments ( Fig. 5 A). White pigment intermittent anteriorly, posteriorly usually in more or less rectangular blocks and concentrated on anterior edge of each segment. Pattern apparent until red-spot pigment and white-head pigment gradually lost when about 50 chaetigers have developed, and white middorsal pigment then taking on characteristic nereidid ‘linked-chain’ pattern. Diffuse greenish anterior colouration of adult can also be discerned at this stage. Region of anterior thick rounded parapodial ligules present, almost as sharply delineated as in adults.

Reproduction. At Wellington P. australis swarming occurred over an extended period late autumn to summer, continuous from June to February (one male captured as early as April), with the period of greatest abundance during late winter to late spring (August–November). Natural spawning occurred readily in the laboratory. When a female P. australis was placed in a small bowl containing a male, both began very rapid swimming round the perimeter and within seconds the male began to emit sperm through the pygidial rosette, followed in 15 to 30 seconds by the female spawning the eggs by dehiscence through the posterior portion of the body. No obvious orientation of worms to each other occurred, worms did not come into contact apart from chance collisions, and they often were swimming in opposite directions as the gametes were released. Females spawned all eggs but males usually retained some sperm. Spawning was not observed in the sea. Interspecies matings were attempted between the combinations P. australis male / P. mahanga female, P. australis female / P. mahanga male, P. australis male / P. k a u female. Usually neither spawned. Occasionally one spawned, usually the male partner. Successful controlled spawnings were achieved with one P. australis female / P. mahanga male cross and one P. australis male / P. mahanga female cross. Spawned eggs developed jelly membranes and started cleavage but embryos died.

Habitat. Intertidal to shallow subtidal in sand and sandy mud substrates. A tough, stringy flexible tube is formed out of detritus and secretions.

Distribution. New Zealand mainland islands and Chatham Islands.

Remarks. The region of anterior thick rounded parapodial ligules is characteristic of several species in the genus, and readily observed in lateral view. In P. australis these ligules are on chaetigers 5–11 as previously noted by Ehlers (1904), and have a basal ring of brown pigmentation. Although Knox (1951) states homogomph falcigers are present, these occur only in juveniles and occasionally in regenerating posterior segments of adults. In wild-collected juveniles of P. australis from the Chatham Islands intertidal single notopodial falcigers were present on the 12th last to about the 5th last chaetigers of 3 late juveniles about 15 mm long and with 44, 53, and 55 chaetigers. A larger juvenile, the largest observed with notopodial falcigers (73 chaetigers, about 25 mm long) had only 2–3 notopodial falcigers remaining on each side.

In P. australis the proboscis is larger in proportion to the head than in the other 3 species, and the maxillary ring often expands in width anteriorly. Area III paragnaths are not as well-developed as in the other three species as usually only three of the five groups are present, and even when best developed the outermost groups are small. Dorsal areas I and II are always without paragnaths, but occasionally in some P. australis heteronereid specimens there is an irregular chitinous patch on area I, and very rarely a small patch on area II not seen in atokes.

In male heteronereids from the Cook Strait region a total of 27 pre-natatory segments was most common, although larger specimens tended to have more segments with a highly significant correlation (correlation coefficient r = 0.539 for n = 49) between the total body length and the number of pre-natatory region segments. Females usually had 6 more pre-natatory segments than males. The mean number of pre-natatory segments in male Port Hutt, Chatham Island specimens (collected 18.ix.50) was 29 (28–31), outside the range occurring at Wellington ( Table 1 ). These specimens were previously reported as females ( Knox 1960) and the record also included another species (see Discussion). The Chatham Islands are separated from New Zealand by about 1000 km of sea. A difference in the number of pre-natatory segments may perhaps have evolved in this isolated population, although further material is needed to confirm this.

FIGURE 2. Platynereis mahanga 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 pygidial papillae structure, dorsal view; C–D, heteronereid male and female natatory 5th pre-pygidial parapodia viewed from anterior. Scale bar: 1 mm A; 0.5 mm B–D.

Heteronereid females of P. australis were significantly longer than the males, and males and females of P. australis were also significantly longer than those of the other species (P<0.05). As expected male P. australis had the longest pre-natatory region of the four species in comparison to total length ( Table 7 ).

Schmarda (1861) named a single female heteronereid collected at Auckland Harbour as Heteronereis australis . Hutchings and Reid (1991) could not refind the type specimen and, according to Dr Hartmann- Schröder, former Curator of Vermes, Hamburg University (pers. comm.), it is doubtful that it still exists. The worm was 36 mm long for 96 segments but Schmarda gave little taxonomically useful detail of the specimen and his colour-plate figure is a stylised representation not showing the heteronereid features. It was probably collected from the intertidal rather than free-swimming. Ehlers (1904 p.26), in addition to describing atokous Platynereis specimens from New Zealand for the first time (as Nereis australis ), re-examined Schmarda's specimen, as also did Augener (1926 p.288). Those two authors describe a basal thickening of the dorsal cirri of the first seven parapodia and a natatory region beginning from the 30th (Augener) or 31st (Ehlers) parapodium. Schmarda’s specimen was thus within the variation of Cook Strait females; the sole Auckland Harbour female heteronereid reported herein was typical for the species with 32 pre-natatory segments and the anterior 6 dorsal cirri enlarged (7th transitional).

Figures

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 1. Platynereis australis male heteronereid pre-natatory region segment totals.

Location	Number of pre-natatory segments										Mean	Std.dev.	n
	24t** 25 25t 26 26t 27	27t	28	28t	29	29t	30	30t	31	31t
Cook Strait*	1 4 1 11 2 21	5	5	0	0	0	0	0	0	0	26.67	0.87	50
Kaikoura	0 0 0 0 0 0	1	2	0	0	0	0	0	0	0	-	-	3
Chatham I.	0 0 0 0 0 0	0	3	2	5	1	1	0	1	1	29.14	1.0 7	14

TABLE 2. Platynereis australis female heteronereid pre-natatory region segment totals.

Location	Number of pre-natatory segments						Mean	Std.dev.	n
	31 31t 32 32t 33 33t	34	34t	35	35t	36
Cook Strait	1 1 8 3 9 2	6	3	3	0	0	33.11	-	36
N.Z.misc.	0 0 1 0 1 0	1	0	0	0	2	-	-	5
N.Z.total	1 1 9 3 10 2	7	3	3	0	2	33.24	1.51	41

TABLE 3. Platynereis australis female heteronereid anterior dorsal enlarged cirri totals.

Location	Number of dorsal enlarged cirri		Mean	Std.dev.	n
	5 5t 6 6t	7
Cook Strait	1 0 16 12	6	6.2	0.52	35