Acoetes bicolor (Grube 1877)

Acoetes bicolor (Grube, 1877)

Panthalis bicolor Grabe, 1877:517 [part].—Hartman, 1939b:86.—Tebble, 1955:74, fig. la–c.—Fauvel and Rullier, 1957:50, fig. 1 [part?].—Rullier, 1964b:1077.

Polyodontes bicolor.—Augener, 1918:119. pl. 2: fig. 28, pl. 3: fig. 47, text-fig. 4a–d [part; not specimen from Bata (= Acoetes bataensis, new species)].

MATERIAL EXAMINED.—WEST AFRICA. Mouth of Congo, Belgian Congo, Gazelle Expedition, lectotype (ZMB 848a) and 2 paralectotypes (ZMB 848b, USNM 50713). West Africa, Hupfer, collector, as Polyodontes bicolor by Augener (1918): Accra, British Gold Coast, 2 specimens (ZMH 597, 598); Seestown, Liberia, 1 specimen (ZMH 600). Gold coast, off Accra, Ghana, identified by Tebble; sta 33, 30 Dec 1950, 28 m, R. Bassindale, collector, 1 specimen (BMNH 1953.3.1.84); Buchanan Survey 3.6–11 m, 1 specimen (BMNH 1953.3.1.85).

TYPE MATERIAL.—The six syntypes of Panthalis bicolor Grube from the Belgian Congo are deposited in the Berlin Museum. The syntypes consisted of a mixture of two species: 3 from ZMB 848 were selected as lectotype and paralectotypes; 2 from ZMB 840 and 1 from ZMB 3252 were selected as types of a new species, Acoetes congoensis.

Lectotype (ZMB 848a) with 42+ segments, 27+ mm long, 9 mm wide with setae, with pharynx completely extended; paralectotype (ZMB 848b) with 78+ segments 65+ mm long, 10 mm wide, with pharynx partially extended; paralectotype (USNM 50713) with 38+ segments, 25+ mm long, 11 mm wide.

DESCRIPTION.—Elytra oval, delicate, with rather large areolae, without color, without lateral pouch on posterior elytra (Figure 54B; Augener, 1918, pl. 2: fig. 28). Prostomium bilobed, oval, with pair of bulbous ommatophores with distinct neck; ceratophore of median antenna on middle of prostomium, with few lateral papillae, with tapered style extending slightly beyond ommatophores; lateral antennae attached ventral to ommatophores with only tips visible dorsally; posterior pair of small eyespots lateral to ceratophore of median antenna; ventral palps long, tapered, more than 3 times length of prostomium, with longitudinal rows of short papillae (Figure 54A). Tentacular segment distinct dorsally; tentaculophores lateral to prostomium, each with bundle of slender setae on inner side and pair of dorsal and ventral tentacular cirri, similar to median antenna (Figure 54A).

Second segment with first pair of elytrophores, ventral buccal cirri longer than following ventral cirri, and biramous parapodia; notopodium as large as neuropodium, with projecting presetal digitiform acicular lobe and wide truncate ruffled postsetal lobe, with fan-shaped bundle of very numerous, long, minutely spinous capillary notosetae; neuropodium with ruffled presetal acicular lobe, rounded postsetal lobe and elongate tapered to rounded ventral bract; neurosetae numerous, slightly wider basally, tapering to long, finely spinous, capillary tips (Figure 54C–G; Augener, 1918, pl. 3: fig. 47, text-fig. 4d). Distal border of extended pharynx with 15 pairs of papillae, middorsal one much larger than others, midventral one only slightly larger or equal in size; 2 pairs of hooked jaws, each with 4–9 lateral teeth.

Third segment with first pair of dorsal cirri with short cirrophores and long styles extending about to tips of setae; ventral cirri short, tapering; parapodia similar to, but not as large as on, segment 2; numerous long notosetae; neurosetae similar to segment 2 with addition of few stout middle acicular ones with long slender tips (Figure 55A–F). Parapodia of segment 8 with small conical notopodium and few short notosetae; upper neurosetae few, short, spinous, lanceolate; rest of neurosetae similar to following parapodia (Figure 55G,H).

Beginning with segment 9, notopodium rounded, flattened, on anterodorsal half of larger neuropodium, with notoaciculum, spinning glands and row of short notosetae emerging from inner side of notopodium; neuropodium with slightly bilobed presetal acicular lobe, truncate postsetal lobe and slightly distinct anteroventral bract; lower neurosetae numerous, within anteroventral bract, slender, slightly curved, with large spines basally and close-set short spines distally; middle row of stout aristate acicular neurosetae; upper group of neurosetae, emerging from low anterodorsal bract, hidden by notopodium, of 2 types: (a) slender, long, tapering abruptly to slender tip, with long subdistal hairs on one side and rows of short spines basally; (b) short, more slender, bipinnate, hidden by notopodium (Figure 55I–L). Posterior parapodia larger; acicular aristate neurosetae with subdistal spinous region on one side; dorsal cirri with wider short cirrophores and short styles; branchiae few, bulbous, on bases of cirrophores and elytrophores (Figure 55M–T; Augener, 1918, text-fig. 4a–c; Fauvel and Rullier, 1957, fig. 1).

DISTRIBUTION.—West Africa. In 3 to 38 meters.