Panthalis zanzibarensis Pettibone 1989

Panthalis zanzibarensis

Panthalis oerstedi.—Monro, 1937:264. [Not Panthalis oerstedi Kinberg, 1856.]

MATERIAL EXAMINED.—British East Africa: Zanzibar, 05°38′S, 39°15′E, 183–194 m, green mud, John Murray Exp. sta 106, 12 Jan 1934, holotype (BMNH 1937.9.2.75, as Panthalis oerstedi by Monro).

TYPE MATERIAL.—Holotype with 44 segments, last 3 small, regenerating, 17 mm long, 5 mm wide with setae.

DESCRIPTION.—Elytra delicate, smooth, opaque, oval, with eccentric attachment near lateral side, with shallow lateral pocket on more posterior elytra (Figure 37B).

Bilobed prostomium with colorless, rounded, short-necked ommatophores on anterior half; median antenna with small nonpapillated ceratophore on middle of prostomium, style missing; lateral antennae inserted ventral to ommatophores, with tips barely extending beyond ommatophores; ventral palps long, tapered, smooth (according to Monro, 1937:264, ommatophores ringed with reddish brown, with reddish eyespots behind bases). Tentacular segment visible dorsally; tentaculophores lateral to prostomium, without setae, with 2 pairs of tentacular cirri, only right ventral tentacular cirrus remaining, longer than lateral antenna (Figure 37A).

Second segment with first pair of elytrophores, long ventral buccal cirri, similar to tentacular cirri, and biramous parapodia; notopodium long, digitiform, with numerous long capillary notosetae extending beyond neurosetae; neuropodium larger, subconical, with prominent anteroventral bract; neurosetae long, finely spinous, with capillary tips, lower ones short, tapering to fine tips (Figure 37A,C,D). Pharynx not extended (not examined).

Third segment with pair of dorsal cirri with short cirrophores and styles extending to tips of neurosetae; notopodium short, rounded, with long capillary notosetae; neuropodium with upper and lower neurosetae similar, lanceolate, spinous; middle row of neurosetae stout, acicular, with tips broken; ventral cirri tapered, almost as long as dorsal cirri (Figure 37A,E–H). Parapodia from segment 4 without notosetae. Parapodia of segment 8 with upper neurosetae similar to those of anterior parapodia, lower neurosetae curved, with prominent spines basally and close-set spines distally; middle stout acicular neurosetae frayed distally, aristate (Figure 37I–L).

Beginning with segment 9, notopodium wide, rounded, flattened, anterodorsal to upper half of neuropodium, with notoaciculum and spinning glands; neuropodium with slightly bilobed presetal acicular lobe, short anterodorsal bract under notopodium, anteroventral bract and truncate postsetal lobe; three groups of neurosetae: lower group numerous, within anteroventral bract, similar to more anterior neurosetae; middle row stout, acicular, hairy distally and subdistally along one side, aristate; upper group, emerging from anteroventral bract, of 2 types: (a) longer, fewer (up to 5 in number), slender with brush-like tips, with or without slender tip; (b) short, more numerous, with widely spaced spines and fine tips (Figures 37M–P, 38A–I). Dorsal cirri short, subulate, shorter than neurosetae; ventral cirri short, tapered, nearly as long as dorsal cirri (Figure 38B,G). Without parapodial branchiae.

ETYMOLOGY.—The species is named for the collection site of Zanzibar.

DISTRIBUTION.—British East Africa. In 183–190 meters.