Parahololepidella nuttingi (Pettibone, 1991) Gonzalez & Conde-Vela & Osborn, 2023

Gonzalez, Brett C., Conde-Vela, Victor M. & Osborn, Karen J., 2023, Synonymization of two, monotypic black-coral-commensal scale worm genera, Antipathipolyeunoa Pettibone, 1991 and Parahololepidella Pettibone, 1969 (Polynoidae, Aphroditiformia), ZooKeys 1178, pp. 61-68 : 61

Parahololepidella nuttingi (Pettibone, 1991) comb. nov.

Fig. 1

Antipathipolyeunoa nuttingi Pettibone, 1991: 716-719, figs 1, 2.

Material examined.

Holotype. Barbados ● 1; Sta. 65, off Payne's Bay Church ; 91 m; 1918; collector CC Nutting; Barbados-Antigua Expedition; on Antipathes tanacetum (now Tanacetipathes ); USNM 80097 . Paratypes. Venezuela ● 3; Sta. 736, W of Tortuga Island ; 10.95, -65.8667; 69-155 m; 22 July 1968; R/ V Pillsbury; on Antipathes tanacetum (now Tanacetipathes ); USNM 136587 .

Redescription

(based on the holotype). Body with numerous segments,>80 (Fig. 1A, B ). Elytra numerous,>40 pairs. Paired elytra on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32, 33, 35, then alternating dorsal cirri and elytra until the end (holotype; Fig. 1A ). Elytral variation present in posterior third of paratypes (see “Variation” below); elytron and dorsal cirrus may occur on same segment (Fig. 1C ). Elytra oval; margins and surface smooth; cover dorsum anteriorly; dorsum exposed on middle and posterior segments (Fig. 1A ). Elytrophores short; less pronounced than dorsal cirrophores. Dorsal tubercles inconspicuous. Dorsal cirrophores not extending beyond notopodia (Fig. 1F ). Dorsal cirrostyles smooth, 5-6 times longer than parapodium.

Prostomium bilobed; anterior notch shallow (Fig. 1D, E ). Cephalic peaks prominent, subtriangular, as continuous extension of the prostomium, equal width to median antenna ceratophore (Fig. 1D, E ). Median antenna in anterior notch (Fig. 1D, E ); ceratophore short, bulbous with smooth ceratostyle, roughly three times the width of the prostomium. Lateral antennae inserted subterminally; ceratophores distinct (Fig. 1D ); styles shorter than palps. Palps short, stout, ~1.5 times the width of the prostomium (Fig. 1B, D, E ). Two pairs of eyes; large, laterally positioned. Tentacular segment (segment 1) not visible dorsally (Fig. 1E ). Dorsal tentacular cirri longer than ventral tentacular cirri. Tentaculophores lateral to prostomium, with single chaeta (Fig. 1D , inset); tentacular styles smooth. Facial tubercle oblong, with smooth rounded margins. Segment 2 (buccal segment) with first pair of elytra and biramous parapodia; nuchal fold absent. Buccal cirri longer than following ventral cirri. Dorsal cirri from segment 3.

Parapodia subbiramous. Notopodia reduced, with subconical lobe (Fig. 1F ). Neuropodia broad; subconical prechaetal lobe longer than postchaetal lobe, with digitiform subacicular process (Fig. 1F, G ). Noto- and neuroacicula penetrating epidermis on some segments (Fig. 1F ). Notochaetae few (9-2) (Fig. 1F ), decreasing posteriorly, less stout than neurochaetae (Fig. 1G, H ). Neurochaetae few (12-6) (Fig. 1F, G ), more numerous in middle segments; shafts smooth (Fig. 1G ); faint spinous rows distally (Fig. 1I ); tips falcate, 4-7 times longer than wide (Fig. 1G, I ), occasionally with small, tooth-like protuberance (Fig. 1J ). Ventral cirri from segment 3, smooth, longer than neuropodium in anterior segments, becoming subequal in length posteriorly. Pygidium rounded. Anus terminal. Anal cirri long, equal in length of last five segments. Nephridial papillae present from segment 6.

Measurements.

Fixed holotype 21.5 mm long, 2.2 mm wide excluding chaetae, 83 segments. The three paratypes (USNM 136587) consist of one posteriorly incomplete specimen, two additional anterior ends, and several middle and posterior fragments. It was only possible to trace one of the two shorter anterior fragments to their respective remaining body fragments. Longest anterior paratype fragment, 24.5 mm long, 2 mm wide excluding chaetae, 85 segments. Reconstructed paratype, 25 mm long, 2.3 mm wide excluding chaetae, 102 segments. Shortest anterior paratype fragment, 5.7 mm long, 1.5 mm wide excluding chaetae, 25 segments.

Variation.

Pigmentation is present in all specimens, present along the midline of the dorsum, with wider bands of pigment present in the paratypes (Fig. 1B ). Additional pigmentation occurs on the cirrophores (Fig. 1B ), but it is otherwise completely lacking (Fig. 1B, C ). Of the two nearly complete paratypes, the elytral distribution patterns are as follows:

Paratype 1.

R: 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32, 33, 35, 37, 38, 41, 43, 45, 47, 49, 52, 54, 56, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85

L: 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32, 34, 36, 38, 41, 43, 45, 47, 49, 51, 53, 55, 56, 58, 59, 60, 62, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85

Paratype 2.

R: 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32, 34, 36, 38, 40, 42, 44, 46, 47, 50, 52, 54, 56, 58, 60, 62, 64, 66, 86, 70, 72, 74, 76, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102.

L: 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32, 33, 35, 37, 39, 41, 43, 45, 47, 49, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102.

Remarks.

The current diagnosis mostly agrees with that of Pettibone (1991) but differs on the presence of chaetae on the tentacular segment (for both holotype and paratypes), and for the irregular distribution pattern of elytra found posteriorly in the paratypes. The holotype only varies from the paratypes in the elytral variation and pigmentation.

Parahololepidella nuttingi comb. nov. is very similar to P. greeffi , but can be differentiated as follows. In P. nuttingi , the dorsal cirrophores are shorter than the notopodium in middle segments, whereas in P. greeffi , the dorsal cirrophores surpass the notopodium (see Pettibone (1991, fig. 1G) and (1969, fig. 4C), respectively). In P. nuttingi , the neurochaetae have falcate tips 4-7 times longer than wide, whereas in P. greeffi , the falcate tips are only 2-3 times longer than wide. And finally, in P. nuttingi , when present, the tooth-like protuberance on the falcate tips of the neurochaetae are small (easily overlooked), whereas in P. greeffi , the tooth-like structures are larger when present, giving them almost a bidentate appearance. Britayev et al. (2014) cautioned that the neurochaetal tooth-like structures in P. greeffi (ZMH 5692) were artifacts due to poor preservation and dehydration over time. However, given that similar structures were found in all specimens of P. nuttingi , we feel that this character is valid and illustrates the importance of detailed microscopical examination and reexamination.

Figures

Figure 1. Parahololepidella nuttingi (Pettibone, 1991) comb. nov., holotype of Antipathipolyeunoa nuttingi USNM 80097 (A, D, F-J); paratype USNM 136587 (B, C, E) A, B whole specimens, dorsal view C dorsal view of middle segments showing variation in elytral distribution; white circles represent dorsal cirrophores and white triangles represent elytrophores D dorsolateral view of anterior with detail (inset) of left tentacular segment (segment 1) showing single chaeta E anterior end, dorsal view A, C-E specimens stained with Shirlastain A to observe morphology in detail F cirrigerous parapodia, ventral view, ventral cirri missing G chaetae from cirrigerous parapodium H notochaetae I distal end of supraacicular neurochaetae J tip of supraacicular neurochaeta with tooth-like protuberance indicated with black arrow. Abbreviations: dCp, dorsal cirrophores; dSt, dorsal style; neC, neurochaetae; noac, notoacicula; noC, notochaetae; SbP, subacicular process. Scale bars: 1 mm (A-C); 0.5 mm (D, E); 0.2 mm (F); 50 μm (G); 20 μm (H, I); 5 μm (J).