Polyodontes frankenbergi Pettibone 1989

Polyodontes frankenbergi

MATERIAL EXAMINED.—NORTH ATLANTIC, OFF GEORGIA. About 35 miles (56 km) off Sapelo Island, 31°20′N, 80°48′W, 18 m, 21 Oct 1964, D. Frankenberg, paratype (USNM 50705). R/V Pierce, 1977: 31°53′N, 80°46′W, 12 m, sta 4B, 25 Aug, paratype (USNM 61001); 31°45′N, 80°28′W, 16 m, sta 4C, 25 Aug, 2 paratypes (USNM 61009); 31°12′N, 81°08′W, 11 m, sta 5B, 21 Feb, paratype (USNM 61033); 31°08′N, 80°50′W, 14 m, sta 5C, 16 May, holotype (USNM 61052) and 31 Aug, 3 paratypes (USNM 61053–61055).

DESCRIPTION.—Specimens all incomplete posteriorly, holotype (USNM 61052) with 60 segments, 38 mm long, and 7 mm wide with setae. Middorsum of anterior region darker. Anterior few pairs of elytra covering dorsum, rest leaving middorsum uncovered. Elytra oval, first pair with scattered dark spots, with small closely packed areolae on most of elytra, with lateral pockets on more posterior elytra (Figure 95B–G).

Prostomium bilobed, with pair of large black oval ommatophores and short narrower necks occupying anterior border, with white domes on tips; median antenna with oval ceratophore on middle of prostomium and lateral papillae, extending posteriorly as raised ridge, with short subulate style not extending beyond ommatophores; pair of small eyespots lateral to ceratophore; lateral antennae inserted ventral to ommatophores and extending only slightly beyond or sometimes hidden from view; palps long, stout, tapered, smooth, about 3 times longer than prostomium (Figure 95A). Tentacular segment distinct dorsally, with raised medial part and few lateral papillae; tentaculophores lateral to prostomium, each with few papillae on dorsal side, 2 acicula, few capillary setae, and pair of short dorsal and ventral tentacular cirri, similar to median antenna (Figure 95A,H).

Second segment with first pair of elytrophores, ventral buccal cirri much longer than following ventral cirri, and biramous parapodia; notopodium conical acicular lobe on anterodorsal side of larger neuropodium, with bundle of long capillary notosetae; neuropodium with rounded presetal acicular and postsetal lobes and prominent lower bract; neurosetae both long and short, slender, wider basally, tapering to finely spinous slender tips (Figure 95I,J). Extended pharynx with 13 pairs of border papillae, middorsal and midventral ones longer than others; 2 pairs of hooked jaws, each with 3–5 lateral teeth. Third segment with first pair of dorsal cirri, with short cirrophores and styles extending slightly beyond setae; middle neurosetae stout, acicular, aristate (Figure 95K–M). Parapodia of segments 4–8 becoming larger, with few, short notosetae; lower neurosetae numerous, within prominent anteroventral bract, with prominent spines on basal enlarged part and close-set spinous rows on tapering curved distal part; middle row of stout acicular aristate neurosetae; upper few neurosetae slender, lanceolate, spinous (Figure 96A–D).

Beginning with segment 9, notopodium wide, rounded, flattened, on anterodorsal half of larger neuropodium, with notoaciculum, spinning gland, and small bundle of short capillary notosetae on lower side; lower and middle neurosetae similar to those of more anterior parapodia; upper group of neurosetae of 2 types: (a) longer, stouter, with close-set spinous rows and slender tips; (b) shorter, more slender, with fewer, widely spaced spinous rows and tapered tips (Figure 96E–H,K).

Middle parapodia becoming larger, with more numerous neurosetae of same types; neuropodia with especially prominent anteroventral bracts enclosing lower group of neurosetae; dorsal cirri with inflated cirrophores and short, subulate styles about as long as ventral cirri; middle acicular neurosetae of more posterior segments with subdistal spines on one side (Figure 96I–O). Without distinct branchiae.

ETYMOLOGY.—The species is named for Dirk Frankenberg, one of the collections of the new species.

DISTRIBUTION.—North Atlantic off Georgia. In 11–16 meters.