Pelogenia zeylanica (Willey 1905)

Pelogenia zeylanica (Willey, 1905)

Psammolyce zeylanica Willey, 1905:255, pl. 1: figs. 33, 34; pl. 2: figs. 35–43.—Horst, 1913:187; 1917:123, pl. 27: figs. 6–8.—Fauvel, 1953:68, fig. 3li.—Gibbs, 1971:128.

MATERIAL EXAMINED.—INDO-PACIFIC OCEAN: Indonesia: JAVA SEA: R/V Siboga stations, identified by Horst (1913, 1917): Sailus Ketjil, Peternoster Is., 27 m, sta 37, 1 specimen (ZMA 1208.3). Anchorage off Pulu Sarassa, Postillion Is., up to 36 m, sta 43, 1 specimen (ZMA 1208.4). FLORES SEA: Sapeh Strait, 08°23.5′S, 119°04.6′E, 69 m, sta 49A, 1 specimen (ZMA 1208.5). Kwandang Bay entrance, North Celebes, 0°58.5′N, 122°55′E, 75 m, sta 114,2 specimens (ZMA 1208.6). MOLUCCA SEA: Anchorage off Lirung, Salibabu Is., up to 36 m, sta 133, 1 specimen (ZMA 1208.7). BANDA SEA: Ambon anchorage, reef, sta 231, 1 specimen (ZMA 1208.8). Banda anchorage, 9–45 m, sta 240, 2 specimens (ZMA 1208.1; USNM 60187). BALI SEA: Anchorage east of Dangar besar, Saleh Bay, up to 36 m, 1 specimen (ZMA 1208.2).

Papua New Guinea: New Britain, 27–37 m, 15 Jun 1895, A. Willey, collector, 1 specimen (BMNH 1923.3.26.5, as Psammolyce arenosa novaebritanniae Willey, unpublished name).

Gilbert Islands: Onotoa, SE end of reef area, sta GOC-36, 20 Aug 1951, P.E. Cloud, collector, 1 specimen (USNM 26076). Mariana Islands: Saipan, sta GOC-30, 2 Aug 1951, P.E. Cloud, collector, 1 specimen (USNM 146127). Solomon Islands: Graham Point, Guadalcanal, low water, silty sand with gravel on Thalassia flat, sta 128, 25 Sep 1965, P.E. Gibbs, collector, 2 specimens (BMNH 1970.165, identified by Gibbs, 1971).

TYPE MATERIAL.—The type specimen from Ceylon is not known to exist. The original type was recorded as 17 mm long and 8 mm wide, with setae, with 30+ segments.

DESCRIPTION.—Figured specimen from Gilbert Islands (USNM 26076) complete, 150 mm long and 10 mm wide, with setae, 176 segments. Dorsum and elytra covered with white calcareous sand, foraminifera, spicules of sponges, and gorgonians. Dorsum with papillae, singly or in groups of 2 to numerous, with flattened cup-shaped tops for attachment of foreign material, plus globular papillae (Figure 25G; Willey, 1905, pl. 1: fig. 33). Ventrum, including lower lip, with numerous long papillae. Elytra thin, transparent, first pair elongate-oval, covered with adhesive papillae and sand grains; following elytra deeply notched medially, forming 2 lobes, posterior lobes longer, both with greater concentrations of adhesive papillae; long papillae on lateral and posterior borders, also with small clavate papillae on borders and surfaces (Figure 26E; Willey, 1905, pl. 2: fig. 42). More posterior elytra with 1–2 additional posterior processes with adhesive papillae and groups of long cylindrical papillae in central parts of elytra (Figure 26F).

Prostomium and tentaculophores fused basally and partially withdrawn in segment II. Prostomium elongate-oval; ceratophore of median antenna large, bulbous basally, with pair of small ctenidia on posterior, basal sides; style as long as or longer than ceratophore; 2 pairs of eyes, smaller dorsal pair lateral to base of ceratophore of median antenna and larger ventral pair; tentaculophores lateral and ventral to prostomium, each with single aciculum, pair of subequal dorsal and ventral tentacular cirri on outer side, and 2 fan-shaped bundles of notosetae and inner tentacular sheath on inner side; lateral antennae short, tapered, attached to dorsal basal sides of tentaculophores; palps emerging lateral and ventral to tentaculophores, long, tapering, with inner palpal sheaths (Figure 25A,B; Willey, 1905, pl. 1: fig. 34; Horst, 1917, pl. 27: figs. 6, 7).

Segment II slightly notched middorsally, with group of papillae with flattened tops and attached sand grains; large elytrophores with small lateral branchiae; ventral buccal cirri extending far beyond tips of neuropodia; notosetae very long, extending beyond tips of neurosetae (Figure 25A,C); neurosetae slender, stems with long spinous regions (up to 25 rows), blades long, with entire hooked tips (Figure 25D; Willey, 1905, pl. 2: fig. 35; Horst, 1917, pl. 27: fig. 8). Pharynx (fully extended) with 11 pairs of border papillae and 2 pairs of dark colored jaws. Segment III with long dorsal cirri attached to dorsal tubercles; cirrophores long, extending to tips of neuropodia, styles shorter, extending to tips of neurosetae (Figure 25E; Willey, 1905, pl. 1: fig. 34; pl. 2: fig. 35); lower neurosetae slender, stems with 6–10 spinous rows, blades long, with bifid, hooked tips; upper neurosetae stouter, stems with 3–4 spinous rows, blades shorter, with bifid, hooked tips (Figure 25F).

Biramous parapodia with notopodia subconical, papillate distally, with larger subdistal flanges enclosing notosetae; low ciliated ctenidia between notopodia and elytrophores or between dorsal tubercles and digitiform branchiae; neuropodia large, subconical, papillate distally, with usual 3 papillate bracts; long papillae on anterior and posterior sides of neuropodia; ventral cirri with long papillae on cirrophores, styles short, tapering, with basal knobs on upper sides (Figure 26A,C; Willey, 1905, pl. 2: fig. 41). Notosetae numerous, as long as neurosetae, extending anteriorly, laterally, and posteroventrally to tips of ventral cirri. Neurosetae compound falcigers, upper and middle ones stouter, upper (3) within dorso-anterior bracts, stems with 1–2 spinous rows, blades slightly hooked, with or without secondary tooth; middle ones (9) within postacicular bracts, similar to upper ones; lower ones (7) within ventro-anterior bracts, stems slender, with single spinous rows, blades long, with bifid, hooked tips (Figure 26B,D; Willey, 1905, pl. 2: figs. 38–40, 43).

DISTRIBUTION.—Indo-Pacific Ocean: Ceylon, Indonesia, Papua New Guinea, Gilbert Islands, Mariana Islands, Solomon Islands; low water to 75 meters.

Montacutona sigalionidcola is a bivalve always found attached to the dorsal surface of the anterior end of the sigalionid host, Pelogenia zeylanica, body