Paraleonnates bolus ( Hutchings and Reid, 1991 )

Hong, Jae-Sang, Choi, Byung-Mee, Kubo, Aki & Sato, Masanori, 2012, Redescription of the giant mud worm Paraleonnates uschakovi Khlebovich and Wu, 1962 (Polychaeta: Nereididae) with special reference to the synonymy of Periserrula leucophryna Paik, 1977 and the difference from Paraleonnates bolus, Zootaxa 3490, pp. 49-62 : 59-60

Paraleonnates bolus ( Hutchings and Reid, 1991)

Figures 3 (D–F), 6(E–G), 8(F, G)

Leonnates bolus Hutchings and Reid, 1991: 48–50 , fig. 1 (type locality: 12˚30΄S 130˚55΄E, mangroves, East Arm , Darwin Harbour, Northern Territory, Australia; holotype: NTM W2518 ).

Paraleonnates bolus: Qiu and Qian, 2000: 1142–1143 , figs 14E, F.

Materials examined. Opposite East Arm Port (12˚31.107'S 130˚52.485'E, Muddy substrate in Sonneratia zone), Wickham Point, Darwin Harbour, Northern Territory, Australia, one specimen, coll. K. Metcalfe, January 2005, det. C. Glasby ( KIBR) .

Diagnosis. Conical paragnaths on dorsal and ventral surfaces of maxillary ring, wholly well sclerotized without whitish base, arranged in two or three irregular transverse rows.

Description of a non-type specimen. Incomplete atokous individual 80 mm in BL, 5.5 mm in BW, with 70 chaetigers, with proboscis retracted. Color greenish gray in anterior dorsum, whitish cream in venter.

Anterior margin of prostomium with deep cleft ( Fig. 3D). Prostomium with pair of smooth tapered antennae and pair of palps as long as antennae. Two pairs of eyes situated in rectangular arrangement; anterior eyes larger than posterior ones.

Peristomium with four pairs of tentacular cirri of unequal lengths; posterior dorsal tentacular cirri longest, reaching back to parapodium 10.

Proboscis with pair of black jaws; inner margin of jaw with about eight distinct teeth. Maxillary ring with two closely neighboring irregular transverse rows of black conical paragnaths interrupted laterally ( Figs 3E, F). Oral ring with two kinds of soft papilla (sharply pointed or blunt); numbers of papillae as follows: area V, none; area VI, single pair of papillae (one sharply-pointed, one blunt) in both right and left sides; area VII–VIII, four sharplypointed papillae arranged in single transverse row.

Notopodial dorsal and ventral ligules triangular, of similar lengths in anterior parapodia; dorsal ligule expanded to round lamella, flattened, leaf-like, with digitate tapering tip on lateral edge, with additional small, round lobe developing above dorsal cirrus, in posterior parapodia behind around parapodium 30 ( Fig. 6G). Rudimentary prechaetal lobe present as small, round protrusion at upper base of notopodial ventral ligules in anterior parapodia. Dorsal cirri slender, tapering, more than two times as long as notopodial dorsal ligule in anterior parapodia, gradually diminishing in size in posterior parapodia.

Neuropodial superior and inferior lobes slender with tapering tip, of similar lengths throughout. Neuropodial postchaetal lobe wide triangular with digitate tapering tip, of similar length as superior and inferior lobes, in anterior parapodia up to about first 10 segments ( Figs 6E, F); digitate tapering tip of postchaetal lobe diminishing to small protrusion on round edge, present up to parapodium 20, and absent in following ones ( Fig. 6G). Neuropodial ventral ligule thick with blunt tip in anterior parapodia, becoming slender in posterior parapodia, of similar length as neuropodial superior and inferior lobes. Ventral cirri slender, tapering, longer than neuropodial ventral ligule in anterior parapodia, gradually diminishing in size in posterior parapodia.

Notochaetae homogomph and sesquigomph spinigers with long, well-serrated blade; few heterogomph spinigers with short, poorly-serrated blades added in upper portion of fascicle of first notopodium (chaetiger 3) ( Fig. 8F). Upper neurochaetae consisting of heterogomph spinigers with short, poorly-serrated blades at superior/ anterior portions, and homogomph and sesquigomph spinigers with long, well-serrated blades at inferior/posterior portions. Lower neurochaetae consisting of heterogomph spinigers with long, well-serrated blades at superior/ posterior portions and heterogomph spinigers with short, poorly-serrated blades at inferior/anterior portions ( Fig. 8G); short blade of heterogomph spinigers with only few teeth at base of lateral side. Falcigers absent throughout.

Remarks. Characteristics of non-type specimen examined in the present study were in good agreement with Hutchings and Reid’s (1991) original description and Qiu and Qian’s (2000) redescription of the holotype. The presence of heterogomph spinigers with short, poorly-serrated blades even in notopodia was first recorded in the present study, although their occurrence in neuropodia was adequately reported previously by Hutchings and Reid (1991). Hutchings and Reid (1991) described the presence of unusual heterogomph falcigers among the lower neurochaetae of parapodium 3 in one of the paratypes. No falciger was observed in the present study.

Notopodial dorsal ligules in posterior parapodia of the non-type specimen of Paraleonnates bolus were more expanded than those of P. uschakovi , and their enlargement associated with development of an additional small lobe above dorsal cirri was shown to be initiated from more anterior parapodium (around parapodium 30) than those in P. uschakovi (around parapodium 70).

Habitat. Mangrove substrates.

Geographical distribution. Northern Australia ( Fig. 1).