Bylgides belfastensis Pettibone 1993

Bylgides belfastensis

MATERIAL EXAMINED.—UNITED STATES: Gulf of Maine, Belfast, at footbridge over Passagassawakeag River, 44°25′54″N, 68°55′52″W, Loyd Clark, collector, Nov, Dec 1969, from C.D. Long, holotype (USNM 74572), 2 paratypes (USNM 74573, 74574).

MEASUREMENTS.—Type Material: Holotype incomplete, with 16 segments, 7 mm long, 7 mm wide including setae. Paratype (USNM 74573) complete but with 14 normal segments, plus 5 small, regenerating segments and growth zone, 7 mm long, 6 mm wide. Paratype (USNM 74574) incomplete, with 22 segments, 8 mm long, 4 mm wide.

DESCRIPTION.—Dorsum transversely banded with blackish grey pigmentation, narrow anterior and wider posterior bands, with spots on dorsal tubercles and on anteromedial sides of elytrophores. Elytra 11 pairs (no specimens complete), on large bulbous elytrophores; elytra large, oval, overlapping, covering dorsum, delicate, with clavate papillae on posterior and lateral borders and on surface; some tubercle-papillae with prominent circular bases on anterior part of elytra (Figure 15B). Dorsal cirri with cylindrical cirrophores on posterodorsal sides of notopodia and long papillate styles extending far beyond setae; dorsal tubercles nodular (Figure 15D).

Prostomium bilobed, wider than long, with small cephalic peaks; 2 pairs of rather small eyes, anterior pair in region of greatest width, slightly larger than posterior pair near posterior border, median antenna with large ceratophore in anterior notch, style long, papillate, with filiform tip; small ceratophores of lateral antennae inserted ventrally, with very short papillate styles; palps stout, tapering, minutely papillate, longer than median antenna (Figure 15A). Tentaculophores lateral to prostomium, with projecting acicular lobe and 2–3 short notosetae on inner side; dorsal tentacular cirri similar to median antenna, ventral tentacular cirri shorter (Figure 15A).

Second segment without nuchal fold, with first pair of elytrophores, biramous parapodia, and ventral buccal cirri lateral to mouth, similar to but shorter than tentacular cirri, longer than following ventral cirri (Figure 15A). Extended pharynx with 9 pairs of border papillae and 2 pairs of jaws.

Parapodia biramous, with notopodium shorter than neuropodium, rounded, with projecting acicular lobe on lower side; neuropodium conical, with projecting presetal acicular lobe and digitiform supraacicular process; postsetal lobe shorter, rounded (Figure 15C,D). Notosetae numerous, forming radiating bundle, much stouter than neurosetae, with close-set spinous rows and rather short, bare, blunt tips; notosetae short, curved, and long, straight (Figure 15C–E). Neurosetae numerous, long, slender, forming fan-shape bundle; upper neurosetae with long spinous regions and long capillary tips (Figure 15F); some middle neurosetae stouter, with long, bare, tapered, blunt tips (Figure 15G); lower meurosetae with shorter spinous regions and shorter capillary tips (Figure 15H). Ventral cirri short, tapered, with minute, globular papillae on upper side (Figure 15C,D). Nephridial papillae indistinct. Pygidium unknown.

DISTRIBUTION.—Gulf of Maine; surface water.

ETYMOLOGY.—The species is named for the collecting site, Belfast, Maine.

COMPARISONS.—Bylgides belfastensis is close to B. fuscus (Hartman and Fauchald). They differ in the form of the elytral papillae and the form of the neuropodial presetal acicular lobes.

Neobylgides, new genus

TYPE SPECIES.—Neobylgides scotiensis, new species. Gender: masculine.

DIAGNOSIS.—Segments up to 47. Elytra and elytrophores 15 pairs, on segments 2, 4, 5, 7, alternate segments to 23, 26, 29, and 32; elytra without microtubercles and papillae. Dorsal cirri on segments lacking elytra, with cylindrical cirrophores and distal styles; nodular to digitiform dorsal tubercles on cirrigerous segments. Prostomium bilobed, without cephalic peaks, with paired palps and 3 antennae; median antenna with ceratophore in anterior notch, lateral antennae with ceratophores inserted ventrally. Tentaculophores of first or tentacular segment lateral to prostomium, each with achaetous acicular lobe on inner side and pair of dorsal and ventral tentacular cirri. Second or buccal segment without nuchal lobe, with first pair of elytrophores, biramous parapodia, and long ventral buccal cirri lateral to mouth; pharynx with 9 pairs of border papillae and 2 pairs of hooked jaws. Parapodia biramous; shorter notopodia with bulbous base and long acicular process; neuropodia subconical with presetal acicular lobe and distal digitiform process; postsetal lobe shorter. Notosetae relatively few, forming radiating bundle, stout, acicular, smooth, much stouter than neurosetae. Neurosetae very numerous, forming fan-shape bundle, tapering to fine tips, with feathery spinous rows up to of exposed length. Ventral cirri on all segments, short, tapered. Pygidium with pair of anal cirri.

Among the genera of Harmothoinae, Neobylgides agrees with Harmothoe Kinberg and Bylgides Chamberlin in the number of segments, number and arrangement of the elytra, and the morphology of the biramous parapodia. Characteristic for the new genus are the elytra lacking microtubercles and papillae, the elongated distal digitiform process on the neuropodial presetal acicular lobe, relatively few of the stout, acicular notosetae lacking spinous rows, and the numerous long neurosetae tapering to fine tips and with numerous feathery spinous rows.