Paleanotus adornatus

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 : 715-717

Paleanotus adornatus species complex

Broad median type

NTM W.25644, QLD, GBR, North Direction Island, 14º44.62’S, 145º30.72’E, CReefs, LI-08-019, coll. C. Glasby, Apr 2008, (1NE); SIO A3629, Indonesia, West Papua, Raja Ampat, Chicken Reef, coll. G. Rouse, 2013, (1E); NTM W.13177, Flores, Maumere, reef off Sao Wisata, coral rubble with encrusting sponges, algae, silty sand, 2.5 m, coll. C. Watson, Aug 1987, (3: 14 NE, 11E, 21NE, W: 0.72 mm); NTM W.13178, Maumere, rubble, algae, sand sample, 24−27 m, coll. B. Russell, Nov 1991, (fragments).

Temperate type

AM W.33487, Geordie Bay, WA, 31º59.5’S, 115º35’E, algae, 10 m, coll. R. Springthorpe, 20 Dec 1983, (1); AM W.23350, Cathedral Rock, Rottnest Island, 32º015’S, 115º27’E, foliose red algae, 6 m, coll. R. Springthorpe, 1983, (1, 34E); NTM W.5124, Albany, North of Geak Point, Stn. RH88-10, 34º58’S, 117º54’E, Posidonia roots & fine sand, coll. C. Erseus, Jan 1988, (4: 1, 33E, L: 3.5 mm, W: 0.9 mm).

Description. (based on holotype and other material where noted). Live body colour whitish with transparent to silvery or pale golden coloured main paleae main covering dorsum; dark red eyes; red pigment in gut plus red spot on ventrum, base of neuropodia. Neuropodia extend little past notopodia.

Notochaetae of mid-body notopodium composed of 2 laterals, broadly pointed distal tips, 5–7 (8) ribs; 1–2 short, pointed subunit 1 paleae, with 4–6 (7) ribs ( Fig. 3 A, D). Main paleae with 11–13 (14) ribs; 1–2 dominant full length finely raised ribs (close to straight margin), plus light, part- length b.l. ribs especially visible basally. Main paleae with slight sloping brow, elevated apices, widely spaced horizontal striae; dorsal cirri 3/4 L of main paleae ( Figs 1 D; 3A–G). Median paleae neatly ‘tuck in’ to main paleae group; number 3, slender, pointed distally, with (8) 9–11 ribs, distinct raised central rib; other lightly raised ribs may be present basally ( Fig. 3 C, D–E).

Neurochaetae of mid-body neuropodium composed of 2 long superior falcigers, 2 shorter falcigers with basal serration; 12 mid-group, medium length falcigers with basal serration; 6–8 inferior group shorter, slender falcigers; total number about 20–25.

Remarks. The small species Paleanotus adornatus n. sp. is described from coral rubble collected from the northern and southern GBR. The largest GBR specimen is 35 segments entire, length 3.5 mm and width 1.0 mm. The species is characterized by main paleae with a slight sloping convex margin, a ‘clean’ dorsal surface with 1−2 full length finely raised ribs and widely spaced horizontal striae ( Figs 1 D; 3A–E).

The species is recognizably present in South-East Asia ( Indonesia and Philippines), across NW Australia and north to the Andaman Sea, Thailand. Paleanotus adornatus n. sp. from GBR to the Philippines possess median paleae with narrow, pointed apices and one prominent central raised rib. Darwin, NW Australian and Thailand material is similar but with slightly broader and less pointed median paleae (cf Fig. 3 C–D and 3E).

Paleanotus adornatus n. sp. and P. inornatus n. sp. are small, similar looking, pale-bodied species with transparent to pale gold paleae and a dark gut showing through. Both species are commonly found sympatrically in coral rubble. The most obvious difference between them is the more pointed median paleae with a distinct raised central rib in P. adornatus n. sp. contrasting with very broad median paleae lacking raised ribs in the latter (detailed comparison in Remarks P. inornatus n. sp.).

Paleanotus adornatus n. sp. can be confused with Paleanotus aquifolia n. sp. especially in preserved material from NE Australian reefs. The colouration is different in the live animals: P. adornatus n. sp. has transparent to pale gold paleae and a white body with dark red piment in the gut and dark red eyes. Paleal fans lie flat across the dorsum and neurochaetae extend a small way beyond notopodia. Paleanotus aquifolia n. sp. has a yellow body, dark maroon eyes and a more distinct golden shine to paleal fans that appear less flattened; neurochaetae extend out beyond dorsum. The two species may be found sympatrically although the micro-habitat differs: P. adornatus n. sp. is commoner in cleaner coral substrates and P. aquifolia n. sp. from sedimented coral rubble and sandy gravels.

Overall the shape of lateral, main and median paleae of P. adornatus n. sp. is marginally broader compared to those of P aquifolia n. sp. However the numbers of ribs of laterals, main and median paleae partially overlap in P. adornatus n. sp. and P aquifolia n. sp. lateral paleae ribs 5–7 vs 4–5(6); main paleae ribs 10–13(14) vs 9–11(12); median paleae ribs 9–11 vs 7–9(10). Paleanotus adornatus n. sp. main paleae appear more ‘clean’ with only two finely raised ribs and wider spaced horizontal striae in comparison to P. aquifolia n. sp. with many broken line raised ribs. Comparing the distal third of the main paleae between the two species, one can see the brow of P. adornatus n. sp. is broader and in P. aquifolia n. sp. the brow is more sloping and narrower ( Fig. 1 D & 1E).

Paleanotus adornatus n. sp. and P. latifolia n. sp. both possess long, pointed median paleae with a raised central rib. Both species are found on the NW Australian coast but do not occur sympatrically. Comparing the distal third of the main paleae between the two species, one can see clearly the different shape of the main; lateral paleae shape is also different (cf Fig. 1 D & 1F).

Paleanotus adornatus species complex includes both tropical and temperate forms. The tropical ‘broad median type’ observed from GBR and Indonesia possesses broader paleael types, especially median; main and median also have more overt finely raised ribs ( Fig. 3 F, G). The paleael rib ranges are similar across all mentioned material. Paleanotus adornatus species complex ‘temperate type’ occurs from three localities in SW Western Australia. Specimens possess similar shaped main and median paleae with central raised rib, to the tropical Paleanotus adornatus n. sp. However the temperate group have mustard coloured bodies and gold paleae in comparison to pale bodied and transparent silvery main paleae of the latter; plus the main paleae lack the two full length finely raised ribs and the median paleae appear comparatively longer. Future DNA analysis of these P. adornatus forms will likely prove new undescribed species are present.

Etymology. The specific name, adornatus , is from the Latin meaning ‘adorned’ and refers to the median paleae group, possessing a single, central raised and ornamented rib, and the main paleae with 1−2 full length lightly raised ribs.

Habitat / Distribution. Paleanotus adornatus n. sp. is found from coarse sand, coral rubble habitats of NE Australian reefs (Lizard Island, Heron Island, inshore GBR reefs); Philippines; N and NW Australia and Andaman Sea, Thailand in depths of 1− 42 m.

Figures

FIGURE 3. Paleanotus adornatus n. sp. A – C: NTM W. 23677: Lizard Island, GBR. A. Lateral group and main paleae; B. Micropic of main palea; C. Median and medial main paleae; D. Micropic of notopodium, NTM W. 23660: Heron Island, GBR; E. Micropic of notopodium, AM W. 7531: Dampier, WA. F – G: P. adornatus broad form. F. Micropic of notopodium and neuropodium, NTM W. 25644: North Direction Island, GBR; G. Micropic of notopodium and neuropodium, SIO A 3629: Indonesia, West Papua, Raja Ampat. Abbreviations: me = median paleae, mm = medial main paleae. Scale bars: A, C = 100 µm.

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.