Sabellomma harrisae, Nogueira, João Miguel De Matos, Fitzhugh, Kirk & Rossi, Maíra Cappellani Silva, 2010

Nogueira, João Miguel De Matos, Fitzhugh, Kirk & Rossi, Maíra Cappellani Silva, 2010, A new genus and new species of fan worms (Polychaeta: Sabellidae) from Atlantic and Pacific Oceans — the formal treatment of taxon names as explanatory hypotheses, Zootaxa 2603, pp. 1-52 : 23-33

Sabellomma harrisae spec. nov.

( Figs 11–15 , 17 ; Table 3)

Material examined. Holotype and 18 paratypes coll. 9 Oct 2006, in shallow subtidal coral rubble, by Leslie Harris et al., near Keelii Lagoon and Sand Island Pacific (21.289o N, 157.87o W), Honolulu Harbour, Oahu, Hawaii. Holotype (LACM-AHF POLY 2413) and 15 paratypes (LACM-AHF POLY 2414–2428) deposited at the NHMLAC; 3 paratypes deposited at the BPBM (BPBM-R3414–3416). Details of each spec. of type series are provided in Table 3.

Additional material. Bernice Pauahi Bishop Museum. BPBM 1283: coll. Honolulu Harbour pier 3–4, Sta. 1, 20 Aug 1997, 3 complete specs plus 4 incomplete specs. BPBM 1237: coll. Honolulu Harbour pier 27, Sta. 7, 23 Sep 1997, 1 complete spec. BPBM 1224: coll. Honolulu Harbour Sealand pier, Sta. 15, 0 5 Nov 1997, 1 incomplete spec.

Definition. Two possibilities, depending on character transformation series in the phylogenetic hypothesis involving individuals to which Sabellomma minuta and S. harrisae spec. nov., refers (see Remarks on Specific-level Hypotheses in Sabellomma ): (1) A specific hypothesis, accounting for the presence of pinnular appendages proximally fused to dorsal lips among observed individuals. The character of proximally fused dorsal lip pinnular appendages originated by an unspecified mechanism(s) in a reproductively isolated population of individuals with pinnular appendages completely fused to dorsal lips, subsequent to which the character became fixed in the population by an unspecified mechanism(s), leading to individuals observed in the present, all with pinnular appendages proximally fused to dorsal lips. (2) There are no autapomorphies to provide a basis for the specific hypothesis.

As is discussed below (see Remarks on Specific-level Hypotheses in Sabellomma ), the definition of S. harrisae is tenuous since the explanation of pinnular appendages partially fused to dorsal lips is not an autapomorphy in some transformation series.

Description. Measurements. Medium-sized individuals; crown 1.5– 4 mm long; 5–8 pairs of radioles, number of radioles often different in left and right halves of crown ( Table 3). Complete specimens with trunk 2.5– 7 mm long, 0.4–0.75 mm wide; 4–5 thoracic and 21–~50 abdominal chaetigers, often with different numbers of thoracic chaetigers in left and right sides of body ( Table 3).

Pigmentation. Live specimens with bright pink radioles alternating lighter and darker pigmented bands, distal one-fifth greenish to brownish; anterior body pink, progressively less pigmented posteriorly, beige to light brown ( Fig. 11 A–B). Crown of preserved specimens with reddish brown pigmentation in proximal onefifth, then alternating white and reddish brown bands ( Fig. 11 C–I). Anterior segments with reddish brown pigmentation around noto- and neuropodia, dorso-laterally lighter and well marked ventrally, on ventral shields; from segment 6, pigmentation progressively lighter ( Fig. 11 C–I); small, conspicuous interramal eyespots throughout ( Fig. 11 E–G, J).

Crown. Radiolar flanges and palmate membrane both absent. Each radiole with four rows of skeletal cells. Radioles with two irregular rows of eyespots along lateral margins ( Fig. 11 C–I); eyespots as single units, each with large lens, more numerous along distal two thirds to one-half of radioles, especially in association with transverse pigmented bands ( Fig. 11 C–I), less abundant near radiolar tips. Dorsal lips less than one-fifth total crown length; basally broad, distally tapering, with radiolar appendages lacking internal skeletal cells; single pinnular appendage present, distal one-half free ( Fig. 12 C, J). Ventral lips low, distally rounded, each continuing ventrally as parallel lamella with large ventral sac above collar ventral lappets ( Fig. 12 C, E, H). Mid-dorsal margins of branchial lobes as thickened ridges, extending along dorsal-most pair of radioles ( Fig. 12 D, I).

Body. Collar fused to body dorso-laterally, well separated from faecal groove, extending anteriorly to level of first pair of parapodia; laterally low, slightly oblique, covering bases of radiolar crown but not origins of radioles; ventrally with one pair of triangular, distally blunt, non-overlapping lappets reaching anterior margin of chaetiger 1, separated from each other by short parallel lamellae ( Figs 11 A, C–I; 12A–B, D–I); ventrally, between termination of parallel lamellae and anterior margin of first ventral shield, ciliated patch present ( Fig. 12 H). Trapezoidal ventral shields, posteriorly indented by neuropodia on thorax ( Figs 11 D, F–G, I; 12A, E, G– H), anterior margin of first shield medially indented ( Figs 11 I; 12E, H). Mid-dorsal faecal groove deep on anterior chaetigers ( Figs 11 C, H; 12B, D, F, I). Collar chaetae narrowly hooded, arranged in two rows ( Figs 12 B, D, F, I; 13A; 14A–B); subsequent thoracic notopodia with narrowly hooded superior chaetae, arranged in arc, inferior chaetae paleate, with long, gently tapering tips, arranged in two rows partially enclosed by Size Number of pairs Number of segments

Length of crown; of radioles Thorax (left; Abdomen (left; Slides Additional data

body length x width (left; right sides of right sides of right sides of (segments)

(mm) crown) body) body)

Complete, in good state of preservation. Crown pigmentation dark red, well

preserved at base and along radioles, on pigmented bands and radiolar Holotype eyespots; body pigmentation as dark reddish area laterally and ventrally on LACM-AHF ~2; ~4.4 x 0.5 6 4 ~40 - collar and thorax, extending on ventral shields until beginning of posterior 2413) body, dorsally lighter, restricted to thorax; conspicuous interramal eyespots

throughout. Photographed for Fig. 11 C–J

Complete, in good state of preservation. Crown pigmentation dark red, well

preserved at base and along radioles, on pigmented bands and radiolar Paratype 1 eyespots; body pigmentation as dark reddish area laterally and ventrally on LACM-AHF 2.5; 5 x 0.5 8; 7 4; 5 +40 - collar and thorax, extending on ventral shields until beginning of posterior 2414) body, dorsally lighter, restricted to thorax; conspicuous interramal eyespots

throughout

Complete, in good state of preservation. Crown pigmentation well preserved

at base and along radioles, on pigmented bands and radiolar eyespots; body Paratype 2 pigmentation as dark reddish area laterally and ventrally on collar and LACM-AHF ~3; 7 x 0.6 7 4 45 - segment 1, progressively lighter along thorax, present on ventral shields until 2415)

th th 4 – 5 abdominal segment; small and fainted, but conspicuous interamal

eyespots throughout. Methil green stained and photographed for Fig. 17 E–F

Complete, in good state of preservation. Crown pigmentation well preserved Paratype 3 at base and along radioles, on pigmented bands and radiolar eyespots; body LACM-AHF ~3; 5 x ~0.5 6; 7 4 44 - pigmentation as light reddish area laterally and ventrally on collar and 2416) segment 1, around neuropodia until end of thorax; fainted, still conspicuous

interramal eyespots throughout

Complete, in good state of preservation, almost cut in two pieces at segment

10 and possibly regenerating posterior segments. Crown pigmentation dark Paratype 4 red, well preserved at base and along radioles, on pigmented bands and LACM-AHF ~1.8; 3.5 x ~0.4 6 4 32 - radiolar eyespots; body pigmentation as dark reddish area laterally and 2417) ventrally on collar and thorax, extending on ventral shields until around

segment 14–15, dorsally lighter, extending until segment 10–11; conspicuous

interramal eyespots throughout

continued next page superior arc ( Figs 12 A–B, D–G; 13B–D; 14A, C–F). Thoracic neuropodia with avicular uncini about as long as high, crest with 4-5 rows of secondary teeth, covering proximal half of main fang; breast distinct, not extending distally to tip of main fang ( Figs 13 F–G; 15A–B); companion chaetae with rounded, symmetrical, denticulate heads and long, tear drop-shaped, slightly asymmetrical, gently tapering membranes ( Figs 13 H; 15A, C). Abdominal neuropodia with narrowly hooded chaetae, arranged in two rows, anterior row with shorter chaetae ( Figs 13 E; 14G–J). Abdominal uncini similar to thoracic, but with shorter handle ( Figs 13 I; 15D–J). Triangular, distally rounded pygidium, with 1–3 small, red ocelli at each lateral margin ( Fig. 11 J).

Variation. The specimens of Sabellomma harrisae examined for the present study do not present remarkable variation, including size ( Table 3). However, several specimens exhibit variation from one side of the body to the other in terms of number of radioles, thoracic and abdominal segments, or both ( Table 3), possibly indicating reproduction by scissiparity, as said above.

Etymology. We dedicate this species to Leslie Harris, Collection Manager of the Polychaete Collection at the NHMLAC, who was responsible for the collection of this material, photographed it alive and was the first to study these specimens.

Distribution. Sabellomma harrisae is only known from Oahu Island, Hawaii.

Figures

FIGURE 11. Sabellomma harrisae gen. nov., sp. nov. A – B: live specimens; C: total worm, dorsal view; D: total worm, ventral view; E: total worm, right lateral view; F: anterior end, right lateral view; G: detail of anterior end, right lateral view; H: anterior end, dorsal view; I: anterior end, ventral view; J: posterior end, left ventro-lateral view. Photos A – B from paratype 11 (LACM-AHF POLY 2424; no track for other specs in photo B), courtesy L. Harris; photos C – J from holotype (LACM-AHF 2413). Scale bars: C – E = 0.5 mm; F = 0.4 mm; G, J = 0.2 mm; H – I = 0.3 mm.

FIGURE 12. Sabellomma harrisae gen. nov., sp. nov. A: anterior end, right lateral view; B: anterior end, left lateral view; C: dissected half crown and lips; D: anterior end, dorsal view; E: anterior end, ventral view; F: anterior end, left lateral view; G: anterior end, right lateral view; H – I: details of collar and base of crown, right ventro-lateral and dorsal views, respectively; J: dorsal lip (dissected crown); unspecified arrow points to connection between dorsal lip and dorsal pinnular appendage. br = branchial ridge; dl = dorsal lip; pa = pinnular appendage; pl = parallel lamellae; ra = radiolar appendage; vs = ventral sacs. Photos A – B, D – I from paratype 6 (LACM-AHF 2419); photos C and J from paratype 12 (LACM-AHF 2425). Scale bars: A, C = 0.3 mm; B = 0.4 mm; D, F – G = 0.1 mm; E, I = 75 µm; H, J = 50 µm.

FIGURE 13. Sabellomma harrisae gen. nov., sp. nov. A: collar chaetae; B: notochaetae from segment 3; C: superior thoracic notochaetae from segment 3; D: inferior thoracic notochaetae (paleae) from segment 3; E: neurochaetae from segment 12; F – G: uncini from segment 3; H: companion chaetae from segment 3; I: uncini from segment 10. All photos from paratype 10 (LACM-AHF 2423). Scale bars: A – E = 30 µm; F, H = 8 µm; G = 15 µm; I = 10 µm.

FIGURE 14. Sabellomma harrisae gen. nov., sp. nov. A: parapodia from segments 1 – 2; B: collar chaetae; C: notochaetae from segment 4; D – F: inferior thoracic notochaetae (paleae) from segments 3, 4 and 4, respectively; G, J: posterior abdominal neurochaetae; H – I: mid-abdominal neurochaetae. All photos from paratype 6 (LACM-AHF 2419). Scale bars: A = 40 µm; B, G – H, J = 20 µm; C = 25 µm; D = 15 µm; E = 5 µm; F = 7 µm; I = 8 µm.

FIGURE 15. Sabellomma harrisae gen. nov., sp. nov. A: neurochaetae from segment 4; B: uncini from segment 3; C: companion chaetae from segment 3; D – E: uncini from segment 6; F, J: anterior abdominal uncini; G – I: posterior abdominal uncini. All photos from paratype 6 (LACM-AHF 2419). Scale bars: A = 15 µm; B = 8 µm; C = 3 µm; D, G, J = 4 µm; E, I = 5 µm; F, H = 2 µm.

FIGURE 17. Methyl green staining. Sabellomma harrisae gen. nov., sp. nov. A – B: total worm; C: anterior end, ventral view; D: posterior end, ventral view; E: total worm, left lateral view; F: posterior end, dorsal view. Photos A – D from spec. BPBM 1237, after ~ 2.5 hours in ethanol after immersion in methyl green solution; photos E – F from paratype 2 (LACM-AHF 2415), after ~ 24 hours in ethanol after immersion in methyl green solution. Scale bars: A = 0.6 mm; B = 1 mm; C, F = 0.3 mm; D = 0.4 mm; E = 0.7 mm.