Paleanotus chrysos, Watson, Charlotte, 2015

Watson, Charlotte, 2015, Seven new species of Paleanotus (Annelida: Chrysopetalidae) described from Lizard Island, Great Barrier Reef, and coral reefs of northern Australia and the Indo-Pacific: two cryptic species pairs revealed between western Pacific Ocean and the eastern Indian Ocean, Zootaxa 4019 (1), pp. 707-732 : 726-729

Paleanotus chrysos n. sp.

( Figs 1 I; 8A −L; 9)

Type material. Holotype: NTM W.23203, Western Pacific Ocean, QLD, GBR, North Direction Island, 14º44.62’S, 145º30.72’E, CReefs, LI-08-019, coll. C. Glasby, Apr 2008, (23E, L: 2.5 mm, W: 0.45 mm). Paratypes: NTM W.25641, same locality as holotype, (6, including female with large eggs, 22 E, L: 2.5mm, W: 0.6 mm).

Other material examined. NTM W.23688, Yonge Reef, 14º34.40’S, 145º37.11’E, CReefs, LI-10-116, Sep 2010, (3: 1, 21E, L: 1.2 mm, W: 0.6 mm); NTM W.23673, Waining Reef, 14º 27.84S, 145º 19.19E, CReefs, LI-09- 0 23, coral rubble, 2 m, coll. C. Watson, Feb 2009, (3E); NTM W.23669, Lizard Island, Coconut Beach, 14º40.88’S, 145º28.35’E, CReefs, LI-09-002, 2 m, coll. C. Watson, Feb 2009, (1, 19E, L: 1.2 mm, W: 0.6 mm); NTM W.23604, Mermaid Beach, 14º38.75’S, 145º27.21’E, CReefs, LI-08-006, fine green algae on sand, 12 m, Apr 2008, (1, 21 E); NTM W.25640, North Point, 14º38.73’S, 145º27.2’E, CReefs, LI-08-020, rubble, 2 m, coll. C. Watson & N. Bruce, Apr 2008, (1, 19E, L: 1.5 mm, W: 0.55 mm); MV F.214507, North east of Townsville, muddy sand, 26 m, (1NE); MV F.214506, Britomart Reef, 18º17’S, 146º38’E, algae & sponges, 3 m, Nov. 1982, (1, 22E, L: 2.3 mm, W: 0.7 mm); MV F 214509, same locality, encrusting algae, Nov 1982, (4, NE); MV F.125877, same locality, reef front, encrusted dead coral with fine red algae, Nov 1982, (1NE); NTM W.23190, Heron Island, CReefs, HI-09-046, Sykes Reef, rubble, 10 m, Nov 2009, (1, 17NE); NTM W.23656, CReefs, HI-10-009, Sykes Reef, rubble, 14 m, coll. M. Blazewicz-Paszokowycz, Nov 2010, (2: 1, 22NE, L: 2.2 mm, W: 0.55 mm; 1, 24E, L: 2.0 mm, W: 0.75 mm); NTM W.23658, North East Lamont Reef, 23º35.20’S, 152º3.73’E, CReefs, HI-10-013, 21 m, coll. M. Capa, Nov 2010, (1, 22E, L: 2 mm, W: 0.65 mm); SMNH 97309, Western Pacific, France, New Caledonia, Loyalty Islands, Lifou, 17 m, (1, 20E, L: 2 mm, W: 0.65 mm).

Paleanotus chrysos species complex

NTM W.13169, Philippines, Luzon, Cape Bolinao, coral rubble, red algae & sponge, 12 m, coll. B. Russell, Oct 1995, (1NE, W: 0.9 mm).

Description. (based on holotype and other material where noted). Very small, elongate body with distinctive paleal notochaetae coloured deep yellow to bright gold. Paleae in neat, slightly ‘prickly’, raised fans over dorsum ie. not completely flattened as in other Paleanotus species. Neuropodia extend a little beyond notopodia.

Prostomium with 2 pairs large, dark maroon eyes often merged; median antenna slender, subulate; large, glandular nuchal fold covers posterior prostomium. Segment 2 (chaetigerous segment 1) with 2–4 slender, pointed paleae with 3 ribs ( Fig. 8 A, B).

Notochaetae of mid-body notopodium composed of 2 slender, pointed laterals with 4–5 ribs; subunit 1 paleae usually absent, sometimes 1–2 small spines present ( Fig. 8 C). Main paleae number 6–8 with 13–15 (16) ribs. Paleae with rounded to slight sloping brow, robust margin serration; broad, curved apices. At moderate magnification superior surface of main paleae appears smooth; at high magnification ribs appear thickened, especially basally, with about 4–6 b.l. ribs. Slender dorsal cirri about 2/3 length of main paleae fan ( Figs 1 I; 8K; 9). Median paleae number 3; distinctive narrow shape with sloping brow. Lizard Island material median paleae slender with distinct ‘upswept’, broad apices, 8–11 (12) ribs ( Fig. 8 E, D). Heron Island, New Caledonian median paleae broader with 9–12 ribs ( Fig. 8 K, L). Median paleae appear smooth; under high magnification 5 b.l. ribs visible, especially basally.

Neurochaetal types of mid-body neuropodium composed of 2 superior, very slender falcigers; about 4 midsuperior falcigers; 6–8 mid-group falcigers. Latter three groups with pronounced basal serrations. Inferior group of shorter falcigers with slender blades, number 4–6. Total number about 20 ( Fig. 8 F–J). Ventral cirri short, subulate.

Remarks. Paleanotus chrysos n. sp. has the smallest maximum body segment number and length compared to all other species described in this paper; e.g., mature GBR specimen 24E, length 2.6 mm, width 0.75 mm; the New Caledonian specimen, 20E and length 3.7 mm. Paleanotus chrysos n. sp. is coloured deep yellow in northern GBR specimens, deep mustard yellow to gold in reefs off Townsville, and bright brassy gold in material from Heron Island, southern GBR: a depth of notochaetal pigmentation not seen in any of the other small Paleanotus species.

Paleanotus chrysos n. sp. is further differientated by possession of pointed lateral paleae with small number of ribs and short spine/s and the absence of sub-unit 1 paleae. The median paleae shape is unique and horizontal striae are observed more widely separated in the basal quarter of paleae becoming finer distally ( Fig. 8 E). Neurochaetal types are similar to those of other species but possess a greater degree of basal serration, particularly of the midgroup falcigers ( Fig. 8 G–I). An ovigerous female paratype specimen (starting to disintegrate), has large eggs present from chaetiger 6, measuring 200–250 µm in diameter ( Fig. 9 ).

Body size and chaetal morphology of individuals from northern and southern GBR specimens, reefs off Townsville and New Caledonia overall agrees. Lizard Island material possesses the narrowest median paleae as do P. chrysos n. sp. from reefs off Townsville. Heron Island specimens exhibits some broader median paleae as well as the narrower ones; the New Caledonian individual has mainly broad median paleae (cf Fig. 8 D, E & K, L).

A New Caledonian specimen is cited as ‘ Paleanotus LI’ in Wiklund et al. (2009). The SMNH specimen on loan for this study is entire so another Paleanotus from the same collection must have been used for the DNA analysis. As there was no morphological description in the paper, a designated species name for the DNA individual is unknown. Future Paleanotus genetic analyses with named species may be able to reveal its identity.

A Philippine individual belonging to Paleanotus chrysos species complex was collected from an encrusted habitat similar to habitats of P. chrysos n. sp. from the GBR. Chaetal types are also very similar e.g., slender lateral paleae and spines, and the egg size is the same. However the main and median paleae have even more elevated apices; paleael sculpture is different with no b.l. ribs on main paleae and the median paleae possess a central raised rib. This specimen appears part of the chrysos complex and may prove to be a new species. Slender, pointed laterals, often accompanied by spines in Paleanotus chrysos n. sp. are also seen in the P. silus n. sp. species complex but the main and median paleae shape are different between the species. P. chrysos has been found sympatric with Paleanotus adornatus n. sp. in coral rubble collections from Lizard Island, GBR.

Etymology. The species name, chrysos , is derived from the Greek meaning ‘gold’ and refers to the distinctive colour of the notochaetal paleae.

Habitat / Distribution. Recorded from the Coral Sea: Lizard Island, reefs off Townsville and Heron Island, GBR, NE coast of Australia and New Caledonia. Paleanotus chrysos n. sp. appears to favour a complex habitat of encrusted coral rubble, red algae, sponges as well as fine algae on sand; depth 2− 30 m.

Figures

FIGURE 8. Paleanotus chrysos n. sp. A – E: NTM W. 23688: Yonge Reef, GBR. A. Anterior end, dorsal view (paleal notochaetae omitted); B. Paleae, segment 2; C. Detail lateral paleae, spine and main paleae; D. Median paleae and medial main palea; E. Micropic, median palea; F – J: Neurochaetal types, NTM W. 23203: North Direction Island, GBR; K. Micropic of midbody segment, SMNH 97309: New Caledonia; L. Detail of median paleae, medial-most main palea, NTM W. 23190: Heron Island, GBR. Abbreviations: ca = caruncle, la = lateral paleae, me = median paleae. Scale bars: A = 200 µm, B – D, F – J, L = 30 µm.

FIGURE 9. Paleanotus chrysos n. sp. Micropic of female with large eggs (body starting to waste), mid-body notochaetael fan in part, NTM W. 25641: North Direction Island, GBR.

FIGURE 1. A. Paleanotus generalized notochaetal fan; B. Main paleae sculptural detail. C – I: Comparative micropics of main palea in Paleanotus new species. C. Paleanotus inornatus n. sp., NTM W. 23684; D. P. adornatus n. sp., NTM. W. 23660; E. P. acquifolia n. sp., NTM W. 23440; F. P. latifolia n. sp., NTM. W. 23710; G. P. silus n. sp., NTM. W. 23731; H. P. silopsis n. sp., NTM W. 23186; I. P. chrysos n. sp., NTM. W. 25641. Abbreviations: b. l = ‘ broken line’sculpture, c = cilia, gl = gland, h. s = horizontal striae, la = lateral paleae, ma = main paleae, me = median paleae, r. r = raised rib, su 1 = sub-unit 1 palea.