Pottsipelogenia treadwelli Pettibone 1997

Pottsipelogenia treadwelli

Psammolyce fijiensis.—Treadwell, 1906:1156.—Hartman, 1966:178.—Bailey-Brock and Hartman, 1987:242.—Not McIntosh, 1885.

MATERIAL EXAMINED.—CENTRAL PACIFIC OCEAN: United States: HAWAII: south coast of Molokai Island, 42–44 m, sandy and stony bottom, R/V Albatross sta 3847, 1902, holotype (USNM 5462, as Psammolyce fijiensis by Treadwell).

DESCRIPTION.—Holotype anterior fragment with 35 segments, 12 mm long and 6 mm wide, with setae; pharynx completely extended. Dorsum, ventrum, and parapodia thickly covered with rusty brown fine sediment. Dorsum with globular papillae and branched adhesive papillae; ventrum thickly covered with short cylindrical papillae, with long papillae on ventral lip region, along midventral groove, and on ventral bases of parapodia. First pair of elytra elongate-oval, with numerous long and short adhesive papillae on surfaces and cylindrical papillae along borders (Figure 56A); 2nd elytra bilobed medially, posterior lobes smaller; adhesive and cylindrical papillae along borders and on surfaces (Figure 56B); more posterior elytra bilobed medially, posterior lobes longer, forming projecting processes, additional rather indistinct, papillate processes on posterior borders with long cylindrical papillae on central parts of surfaces and with adhesive cylindrical papillae with flattened tops concentrated on medial fourth; antero-lateral borders wavy, with groups of long papillae alternating with globular papillae (Figure 56C).

Prostomium and tentaculophores fused basally and partially withdrawn in segment II; prostomium oval, with 2 pairs of eyes, ventral pair about 2 times larger than dorsal pair; median antenna with large bulbous ceratophore with lateral ridges and oval ctenidia on basal sides anterior to dorsal eyes, style missing; tentaculophores each with single aciculum, dorsal tentacular cirrus about as long as ceratophore, ventral tentacular cirrus missing on outer side, and 2 bundles of capillary notosetae and delicate inner tentacular sheath on inner side; palps long, tapered, with inner palpal sheaths continuous with inner tentacular sheaths; lateral antennae short, attached to dorsal inner sides of tentaculophores; clavate facial tubercle attached to upper lip just ventral to fused inner tentacular sheaths (Figure 56D,E). Segment II with middorsal papillate mound with branched adhesive papillae (and adherent sand grains) between first pair of large elytrophores, with lateral branchiae; biramous parapodia with neuropodia papillate distally and with subdistal bracts with long papillae; long tapering ventral buccal cirri; neurosetae slender, stems with long spinous regions, blades long, with slender, hooked tips (Figures 56D,E, 57A,B). Extended pharynx with 11 pairs of border papillae and 2 pairs of amber-colored jaws. Segment III with dorsal tubercles and long dorsal cirri; cirrophores short, with branchiae on lower sides, styles broken off (presumably long); lower neurosetae similar to those on segment II but slightly stouter, with shorter spinous regions and blades long with bifid, hooked tips; upper neurosetae stouter, stems with 4–11 spinous rows, blades shorter, with bifid, hooked tips (Figure 57C,D).

Biramous parapodia with notopodia smaller than neuropodia; notopodia subconical, with large subdistal flanges enclosing numerous notosetae; without distinct ctenidia but with low ridges in curved areas between notopodia and branchiae and between elytrophores and dorsal tubercles; neuropodia large, subconical, with long papillae distally and with usual 3 subdistal bracts, but with extra long papillae, enclosing neurosetae; ventral cirri with cirrophores with short papillae, styles tapered, with basal knobs on upper sides; anterior and posterior sides of neuropodia with globular papillae; groups of long papillae medial to ventral cirri. Notosetae numerous spinous capillaries, extending dorsally, laterally, and posteroventrally, beyond ventral cirri (Figure 57E). Neurosetae stout compound falcigers, mostly with bifid hooked tips; upper ones (3–4) within dorso-anterior bracts, stems with 3–6 spinous rows, blades moderately long; middle ones (9–10) within C-shaped postacicular bracts, stems with single spinous rows, blades mostly shorter; lower ones (5–6) within ventro-anterior bracts, stems with 1–3 spinous rows, blades long (Figure 57F).

ETYMOLOGY.—The species is named for Aaron Louis Treadwell, who earlier examined the specimen herein selected as the holotype.

COMPARISONS.—Pottsipelogenia treadwelli agrees with P. gracilis (McIntosh) in having the first pair of elytra elongateoval and not deeply bilobed, as in the other species of Pottsipelogenia. In P. treadwelli the middorsum of segment II bears a mound with adhesive papillae, which is lacking on P. gracilis.

DISTRIBUTION.—Central Pacific Ocean: Hawaii; in 42 to 44 meters.