Paradalhousia oculata ( Treadwell, 1906 ), 2020

Salazar-Vallejo, Sergio I., 2020, Revision of Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 (Annelida, Errantia, Hesionidae), Zootaxa 4739 (1), pp. 1-114 : 86-88

Paradalhousia oculata ( Treadwell, 1906) n. comb., reinstated

Figs 49, 50

Castalia oculata Treadwell 1906: 1148 , Figs 1–3.

? Leocrates oculatus: Hartman 1956: 278 .

Leocrates oculatus: Hartman 1966: 191–192 (n. comb.).

Leocrates giardi: Pettibone 1970: 219-221 , Figs 17–19 (only Fig. 17); Bailey-Brock & Hartman 1987: 263–264, Fig. 3.II.34 (non Gravier, 1900).

Type material. Hawaii. Holotype ( USNM 5200 ), Maui Island, South of Puhielele Point (21°36’35” N, 156°05’10” W), Aleunihana Channel , between Hawaii and Maui Islands , USFC Steamer Albatross , Sta. 4066, 88– 317 m, rocky bottom, 18 Jul. 1902.

Additional material. Hawaii. One specimen ( AMNH 476 ), no further data [labelled as syntype; 7.1 mm long, 2.3 mm wide] .

Description. Holotype (USNM 5200) complete, bent ventrally, breaking into two ( Fig. 49A), pharynx fully exposed; left parapodia of chaetigers 6–9, and right parapodia of chaetigers 6–7 previously removed (all in container). Body colorless, 11 mm long, 2 mm wide, 16 chaetigers; eyes brownish, middorsal peristomial tubercle pale; most cirri broken.

Prostomium slightly longer than wide, slightly wider anteriorly ( Fig. 49B, C). Lateral antennae with ceratophores distinct, longer than prostomium, slightly longer than palps; palpophores slightly longer than palpostyles. Median antenna broken, inserted between anterior eyes.

Eyes brownish, round; anterior eyes emarginate anterolaterally, slightly larger and slightly more distant to each other than posterior round ones; in lateral view anterior and posterior eyes fused ( Fig. 49B, C).

Nuchal organs lobes U-shaped, parallel, prostomial posterior projections pale; middle furrow deep. Lateral ciliated bands visible dorsally. Tentacular cirri mostly broken or without tips, longest one reaching chaetiger 6. Lateral cushions low, entire, longitudinal striae visible.

Pharynx fully everted; anterior margin with 24 denticles, middorsal and midventral areas bare ( Fig. 49D). Upper and lower jaws single, visible, exposed, brownish in frontal view.

Dorsal cirri without tips, about as long as body width (excluding parapodia). Chaetigers 1–3 without notochaetae, notochaetae present along chaetigers 4–16, about 50 per bundle, as long as neurochaetae, subdistally denticulate, denticles fine, small. Notacicular and neuracicular lobes tapered, blunt ( Fig. 49E, insets); notacicular lobes twice longer than wide, neuracicular ones as long as wide. Neurochaetae about 50 per bundle, blades decreasing in size ventrally, 6–7 times longer than wide; blades bidentate, guard approaching subdistal tooth ( Fig. 49E insets).

Posterior region tapered. Prepygidial segment without dorsal cirri, ventral cirri medially broken. Pygidium tubular, anal cirri missing.

Oocytes about 100 µm.

Remarks. Castalia oculata Treadwell, 1906 must be reinstated and newly combined. Pettibone (1970: 219) regarded it as a junior synonym of Leocrates giardi Gravier, 1900 , but they belong to different genera. Further, C. oculata deserves a new combination into Paradalhousia because it has U-shaped nuchal organs, single upper and lower jaws, and pale neurochaetae. On the other hand, P. oculata ( Treadwell, 1906) n. comb., resembles P. papillosa ( Monro, 1926) reinst., n. comb. but they differ in the number of neurochaetae and in the orientation of their teeth. In P. oculata there are about 50 neurochaetae per bundle, and their distal teeth are slightly falcate, whereas in P. papillosa neurochaetae number about 20(–30) per bundle, and their distal teeth are straight.

The specimen deposited in New York (AMNH 476) is labeled as syntype. However, it was not included in the original description, which is the requisite in order to be included as a syntype ( ICZN 1999, Art. 72.4.1), and consequently it is herein regarded as an additional specimen. However, it completely matches the holotype in body shape ( Fig. 50A), anterior end appendages ( Fig. 50B), and pharynx features ( Fig. 50C), rendering it enigmatic why it was not included in the original description.

Distribution. Hawaii, rocky bottoms in 88–317 m depth.