Polyodontes panamensis (Chamberlin 1919)

Polyodontes panamensis (Chamberlin, 1919)

Panthalis panamensis Chamberlin, 1919:86, pl. 11: figs. 4–8, pl. 12: figs. 1–6. [Not sensu Treadwell, 1936:265 (= Acoetes melanonota (Grube, 1870), new combination).]

Polyodontes mortenseni Monro, 1928:569 [part].

Panthalis adumbrata.—Treadwell, 1937:147. [Not Panthalis adumbrata Hoagland, 1920 (= Polyodontes atromarginatus Horst).]

Polyodontes panamensis.—Berkeley and Berkeley, 1939:326.—Hartman, 1939b:84.—Emerson, 1971:139.—Fauchald, 1972:30.

MATERIAL EXAMINED.—PANAMA (Pacific). Panama, shore, Albatross sta, 30 Mar 1900, holotype of P. panamensis (USNM 19431). Melones, 6–9 m, 15 Dec 1915, Th. Mortensen, collector, syntype of Polyodontes mortenseni (UZMC, not same as lectotype and paralectotype from Taboga).

LOWER CALIFORNIA. Arena Bank, 101 m, 19 Apr 1936, Wm. Beebe, collector, 1 specimen (AMNH 3937, as P. adumbrata by Treadwell, 1937).

MEXICO. Acapulco, 16°51′N, 99°54′W, dredged at anchorage, sand and shell, 6 Apr 1937, F.E. Lewis, collector, MS Stranger, 2 specimens (USNM 35019, 50701).

TYPE MATERIAL.—Holotype, a female with eggs in body cavity, is an anterior fragment of 61 segments, 30 mm long, and 6 mm wide with setae; the pharynx is fully extended.

DESCRIPTION.—Anterior few pairs of elytra covering dorsum, rest leaving middorsum uncovered; elytra elongate, oval, thin, delicate, transparent, showing closely packed areolate pattern, brownish on medial half, with shallow to rather deep lateral pockets (Chamberlin, 1919, pl. 12: figs. 5, 6; Hartman, 1939b, pl. 24: fig. 291).

Prostomium bilobed with pair of bulbous ommatophores with short necks; median antenna with ceratophore on middle of prostomium, with 2 pairs of lateral papillae, extending posteriorly as slightly raised ridge, style extending slightly beyond tips of ommatophores; pair of small eyes lateral to ceratophore of median antenna; lateral antennae inserted ventral to ommatophores and extending slightly beyond; palps stout, tapered, smooth, about twice as long as prostomium (Figure 82A; Chamberlin, 1919, pl. 11: fig. 4). Tentacular segment visible dorsally; tentaculophores lateral to prostomium, each with longitudinal row of papillae on inner side, 2 acicula, few setae, and pair of dorsal and ventral tentacular cirri, similar to median antenna (Figure 82A; Chamberlin, 1919, pl. 11: fig. 4).

Second segment with first pair of elytrophores, ventral buccal cirri much longer than following ventral cirri, and biramous parapodia; notopodium long, subconical, with bundle of long capillary notosetae; neuropodiuim with slightly bilobed presetal acicular lobe and truncate postsetal lobe, with slightly developed ventral bract; neurosetae numerous, slender, slightly enlarged basally, tapering to spinous capillary tips, lower ones shorter (Figure 82B–D; Chamberlin, 1919, pl. 12: fig. 1; Hartman, 1939b, pl. 24: fig. 290). Extended pharynx with 13 pairs of border papillae, middorsal and midventral ones on wide lobulated bases, middorsal one much longer than others, midventral one only slightly longer, 2 pairs of hooked jaws, each with 2–5 lateral teeth (Chamberlin, 1919, pl. 11: fig. 4).

Third segment with first pair of dorsal cirri with short cirrophores and styles extending about to tips of setae; notopodium and notosetae similar to those of segment 2; neuropodium with distinct ventral bract; upper neurosetae lanceolate, spinous; middle neurosetae stout, acicular, aristate; lower neurosetae slightly curved, spinous (Figure 82E–H; Chamberlin, 1919, pl 11: figs. 5, 6). Parapodia of segments 4–8 with notopodia smaller, with few and short notosetae; upper neurosetae lanceolate, spinous; middle neurosetae stout, acicular, aristate, with slightly hooked tips, some with subdistal rows of spines on one side; lower neurosetae, within anteroventral bract, slightly curved, with larger spines basally and close set spinous rows distally (Figure 82I–L).

Beginning with segment 9, notopodium wide, rounded, flattened, on anterodorsal half of larger neuropodium, with notoaciculum, spinning gland, and row of short notosetae from underside of notopodium; neuropodium with lower and middle neurosetae as in more anterior parapodia; upper group of neurosetae of 2 types: (a) longer, stouter, lanceolate, spinous; (b) shorter, more slender, bipinnate, with short sharp tips (Figure 82M–O).

More posterior parapodia larger; cirrophores of dorsal cirri inflated, with styles wider and shorter; upper neurosetae with long spines subdistally (Figure 82P–T; Chamberlin, 1919, pl. 11: figs. 7, 8; Hartman, 1939b, pl. 24: figs. 289, 292, 293). Holotype without distinct parapodial branchiae; with single digitiform branchiae beginning about segment 30 on some specimens.

DISTRIBUTION.—Southern California (Santa Barbara Channel), Panama (Pacific), Lower California, Gulf of California, to Mexico (Acapulco). In low water to 280 meters.