Paradalhousia anomala ( Chamberlin, 1919 ), 2020

Salazar-Vallejo, Sergio I., 2020, Revision of Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 (Annelida, Errantia, Hesionidae), Zootaxa 4739 (1), pp. 1-114 : 82-86

Paradalhousia anomala ( Chamberlin, 1919) reinst., n. comb.

Figs 46–48

Leocrates anomalus Chamberlin, 1919: 190–191 .

Leocrates giardi: Pettibone 1970: 219 , Fig. 18a, b (partim, non Gravier, 1900).

Type material. Western Pacific. Marshall Islands. Holotype ( USNM 19392 ), USFCS Albatross Pacific Expedition , 1899–1900, Unnumb. Sta. (Marshall Islands 9° N, 168° E), came up on anchor, 21.6 m, Dec. 1899.

Additional material. Western Pacific. Micronesia. Two specimens ( USNM 29981 ), Pacific Science Board , Sta. 172, lagoon edge of lagoon reef, Tiatua , Kapingamarangi Atoll, Sta. 137 (01°04’00” N, 154°47’00” E), 13 Jul. 1954, C. Hand, coll. [15 mm long, 3 mm wide] . Two specimens ( USNM 37643 ), Kapingamarangi Atoll, G.F.V. Sta. 137 (01°21’00” N, 154°45’14” E), 12 Aug. 1954, G.F.V., coll. [partially dehydrated, larger one complete, the other without posterior end, some parapodia previously removed; both already dissected midventrally for pharynx details; best specimen 20 mm long, 2.5 mm wide] . Japan, Ryukyu Islands . Two specimens ( MCZ ANNa 84731),

Horshoe Cliffs, 1 km WNW from Onna Village (26°30’ N, 127°50.9’ E), 63 m, mixed sand and coral rubble, 1 Jun. 1995, R.F. Bolland, coll. [18.5–21.0 mm long, 2.8–3.5 mm wide]. Cook Islands. One specimen ( UF 393 ), Ma’uke Island, off Kimiangatau (20°08’48” S, 157°21’00” W), under rocks, 50–52 m, 4 Dec. 1984, G. Paulay, coll. [13 mm long, 2 mm wide] . New Caledonia. 10 specimens ( SIO A5582 ), Îles Loyauté , Baie du Santal , Lifou, Récif Shelter (20°53’45.00” S, 167°03’30.0024” E), 0–17 m, 18 Nov. 2000, F. Pleijel, coll. [10–14 mm long, 2

mm wide]. French Polynesia, Society Islands , Moorea . One specimen ( SIO A4233 ), W side of Cook’s Pass , near MPA Marker (17°28’53.40” S, 149°49’30.00” W), no depth given, 9 Nov. 2010, G. Rouse, coll. [13 mm long, 1 mm wide] . One specimen ( SIO A11840), W side of Opunohu Pinnacle (17°29’38.76” S, 149°51’43.20” W), 10 m, 11 Nov. 2010. C. Meyer, coll. [13.5 mm long, 1 mm wide] . One specimen ( UF 855 ), off E of Opunohu Pass, Shark Feeding buoy (17°28’54.12” S, 149°51’20.88” W), outer reef slope, 17–18 m, rubble and sand, 16 Oct. 2008, S. McKeon, J. Moore & G. Paulay, coll. [9.5 mm long, 1.5 mm wide] . One specimen ( UF 868 ), between Temae and Afareaitu, outer reef (17°30’52.20” S, 149°45’41.76” W), 30 m, slope base, rubble field, rubble brushing, 23 Oct. 2008, C. Meyer, S. McKeon & J. Moore, coll. [12 mm long, 1.5 mm wide] . One specimen ( UF 2150 ), off Hilton , forereef (17°28’31.44” S, 149°50’31.20” W), 40 m, rubble, 9 Nov. 2010, K. White, coll. [4 mm long, 1 mm wide] . One specimen ( UF 3030 ), off Motu Ahi , north of Afareitu Pass (17°33’09.36” S, 149°46’24.60” W), 57 m, deep reef slope, rubble, 22 Jan. 2012, R. Whitton, coll. [13 mm long, 2 mm wide] . One specimen ( UF 3047 ), off NW Motus (17°29’10.32” S, 149°55’27.48” W), 66–72 m, deep reef slope, 28 Jan. 2012, J. Earle, D. Pence, R. Pyle, coll. [10 mm long, 1.5 mm wide, 11/12 chaetigers] .

Redescription. Holotype (USNM 19392) dried-out, distorted; anterior region swollen, middle and posterior regions collapsed, directed upward ( Fig. 46A ). Body obconic, anteriorly blunt, posteriorly tapered, 16 mm long, 4.5 mm wide; left parapodia of chaetigers 10 and 12 previously dissected (in container); pharynx previously dissected midventrally. Tentacular cirri, and dorsal and ventral cirri missing. Body pale, eyes dark brown, posterior prostomial projections brownish.

Prostomium longer than wide, slightly wider anteriorly ( Fig. 46B, C ). Palps and lateral antennae collapsed, not manipulated to avoid further damage. Median antenna broken, basal region visible, inserted between posterior eyes. Anterior eyes twice larger than posterior ones, slightly more distant to each other than posterior ones; in lateral view, eyes almost fused.

Nuchal organs lobes divergent, tear-drop shaped; posterior prostomial areas paler than eyes. Lateral cushions low, barely projected, entire or bifid along body, longitudinal striae visible.

Pharynx partially exposed ( Fig. 46D ). Anterior margin with 20 oval brownish denticles, slightly larger ventrally; dorsal jaw single, brownish, exposed, inserted below pharynx margin; ventral jaw not seen, probably destroyed by previous dissection.

Chaetigers 1–3 without notochaetae; notochaetae present along chaetigers 4–16, very abundant, delicate, probably eroded, surface smooth. Dorsal cirri length in relation to body width unknown. Notacicular and neuracicular lobes of similar length, tapered ( Fig. 46E , insets), acicula black, tapered; ventral cirri dehydrated, tip broken, relative length unknown. Neurochaetal tips missing; blades unknown.

Posterior region tapered, dehydrated, without lateral or anal cirri. Pygidium with anus terminal.

Immature gonad observed with oocytes, each about 25 µm in diameter ( Fig. 46E , inset).

Variation. Better preserved, non-type specimens (USNM 29981: 15 mm long, 3 mm wide, MCZ 84731: 18.5– 21.0 mm long, 2.8–3.5 mm wide) slightly dehydrated, bent laterally ( Fig. 47A ), or less dehydrated ( Fig. 48E ). Body obconic, anterior region blunt, posterior region tapered; pharynx previously dissected midventrally. Many tentacular cirri and dorsal cirri missing. Body pale, eyes dark brown.

Prostomium longer than wide, slightly wider anteriorly ( Figs 47B , 48A, F ). Lateral antennae 1 / 3 longer than palps. Palpophores slightly longer than palpostyles. Median antenna short, delicate, apparently complete, not reaching anterior prostomial margin.

Eyes brownish, anterior ones slightly larger than posterior ones ( Figs 47A, B , 48A, F ); in lateral view, eyes almost fused. Nuchal organs lobes tear-drop shaped with posterior prostomial areas pale, take Methyl green stain.

Pharynx previously dissected ( Figs 47C , 48C, D ). Anterior margin with 28 oval brownish denticles, slightly larger ventrolaterally; dorsal jaw single, brownish, exposed, inserted below pharynx margin; ventral jaw not seen, probably destroyed by previous dissection.

Chaetigers 1–3 without notochaetae; notochaetae present along chaetigers 4-16, very abundant, delicate, subdistal denticles fine. Dorsal cirri as long as body width (without parapodia). Notacicular and neuracicular lobes tapered ( Figs 47D , insets, 48B, G), aciculae black, tapered; ventral cirri surpassing neurochatal lobes. Neurochaetae with blades decreasing in size ventrally ( Fig. 47E ), bidentate, 5–22 times longer than wide, guards approaching subdistal tooth ( Fig. 47F ).

Posterior region tapered, prepygidial segment with dorsal and ventral cirrophores, cirrostyles missing. Pygidium with anus terminal, ventral cirri missing.

Oocytes not seen.

Remarks. Leocrates anomalus Chamberlin, 1919 must be reinstated. Pettibone (1970: 219) regarded it as a junior synonym of L. giardi Gravier, 1900 , but these two species belong to different genera, as herein revised, and hence a new combination is proposed below. Chamberlin (1919) made no illustrations for the original description, and Pettibone (1970) did not make any for it despite the fact she studied the holotype. The marginal pharynx denticles present in P. anomala and in two other species also included in this genus (see below), are not present in any Leocrates species.

Further, this species is newly combined into Paradalhousia anomala ( Chamberlin, 1919) because it has Ushaped nuchal or tear-drop shaped lobes, single upper and lower jaws, and pale neurochaetae. This combination of characters is herein regarded as diagnostic for Paradalhousia . The marginal teeth present in the pharynx of Paradalhousia species resemble a syllid trepan, and the presence of a middorsal jaw at a certain distance of the pharynx margin, makes this resemblance even stronger. It must be stressed that this type of pharynx armature has not been described before in any genus of Hesionidae .

Paradalhousia anomala differs from the two other species also newly recombined and reinstated: P. oculata ( Treadwell, 1906) , and P. papillosa ( Monro, 1926) , especially in the shape of nuchal organs lobes. In P. anomala nuchal organs lobes are divergent, whereas in the two other species the nuchal organs lobes are parallel.

On the other hand, P. anomala was described with a specimen from the Marshall Islands. Chamberlin (1919: 191) indicated that acicular lobes were tapered (‘acutely pointed’), and although there was no explanation for the specific name, it was probably selected after the observation of ‘a half circle of conspicuous, chitinized, round papillae’ what separates this species ‘from other species of the region.’ He did not call these structures as either denticles or teeth, but he regarded them as sclerotized papillae one page ahead, and by referring to nereidid pharynx he wrote ( Chamberlin 1919: 192): ‘soft or hard papillae, or teeth, the paragnatha (sic), which are of much significance in classification.’

Distribution. Japan (Ryukyu Islands) to Micronesia, French Polynesia and New Caledonia, in coral environments, in 10–72 m depth.

Figures

FIGURE 18. Lamprophaea longicirrata (Treadwell, 1902), new combination, holotype (USNM 15915), MGS. A. Anterior region, dorsal view. B. Anterior end, dorsal view. C. Anterior end, ventral view. D. Chaetiger 10, right parapodium, anterior view (insets: longest and shortest neurochaetal blades, and notacicular lobe). Scale bars: A: 0.7 mm, B, C: 0.6 mm, D: 0.9 mm.

FIGURE 46. Paradalhousia anomala (Chamberlin, 1919), n. comb., reinstated, holotype (USNM 19392). A. Dorsal view, middle region collapsed, posterior region bent dorsally and to the left. B. Anterior end, dorsal view (*: denticle). C. Same, MGS (*: denticle). D. Same, anterior region, ventral view, dissection previously made; pharynx margin with radial denticles. E. Chaetiger 10 (or 12), left parapodium, anterior view (insets: noto- (left) and neuracicular (right) lobes and fragment of gonad, indicated by an asterisk). Scale bars: A: 1.6 mm, B, C: 0.2 mm, D: 0.4 mm, E: 0.3 mm.

FIGURE 47. Paradalhousia anomala (Chamberlin, 1919) n. comb., reinstated, non-type specimen (USNM 29981). A. Anterior region, dorsal view. B. Anterior end, dorsal view, MGS. C. Anterior end, ventral view, pharynx margin with denticles. D. Chaetiger 7 or 9, left parapodium (insets: (upper) notacicular and (lower) neuracicular lobes). E. Same, neurochaetal tips (*: blade enlarged). F. Same, neurochaetal blade indicated by an asterisk in E. Scale bars: A: 0.6 mm, B, D: 0.2 mm, C: 0.3 mm, E: 70 µm, F: 20 µm.

FIGURE 48. Paradalhousia anomala (Chamberlin, 1919) new combination, reinstated, non-type specimens (MCZ ANNa 84731). A. Smaller specimen, anterior end, dorsal view, MGS. B. Same, chaetiger 8, right parapodium, anterior view. C. Anterior region of pharynx, dissected midventrally. D. Same, close up of subdistal ring of denticles. E. Larger specimen, anterior region, dorsal view. F. Same, anterior end, dorsal view, MGS. G. Same, chaetiger 8, right parapodium, anterior view. Scale bars: A, B: 0.5 mm, C, G: 0.6 mm, D, F: 0.3 mm, E: 0.7 mm.