Panthalis alaminosae Pettibone 1989

Panthalis alaminosae

Polyodontes sp. A.—Wolf, 1984:5 [part].

MATERIAL EXAMINED.—GULF OF MEXICO. R/V Alaminos cruises, 1967, 1968, from L.H. Pequegnat: 67 A5–9A, 19 Jul, 29°27′N, 86°57′W, 752 m, 7 paratypes (USNM 98800); 68 A7–2A, 26 Jul, 28°56′N, 88°42′W, 408 m, 2 paratypes (USNM 98801). 68 A7–9A, 4 Aug, 29°27.6′N, 86°45.5′W, 389 m, 5 paratypes (USNM 98802); 68 A7–10A, 4 Aug, 29°15.5′N, 86°55′W, 566 m, paratype (USNM 98803); 68 A13–4, 12 Nov, 25°38.4′N, 96°18.3′W, 512 m, holotype (USNM 98797), 11 paratypes (USNM 98798–9); 68 A13–18, 19 Nov, 27°45′N, 95°16′W, 439 m, 4 paratypes (USNM 98804); 68 A13–19, 19 Nov, 27°44.9′N, 95°20′W, 338–384 m, 6 paratypes (USNM 98805). Mississippi-Alabama-Florida Outer Continental Shelf Study (MAFLA) sta 2312D, Jul 1976, 28°23′59.3″N, 85°15′03″W, 177 m, clayey sandy silt, 1 specimen (BAV, as Polyodontes sp. A by Wolf, 1984). South Texas Outer Continental Shelf Study (STOCS) sta 3/II-2, Fall 1976, 27°30′N, 96°45′W, 49 m, silty clay, juvenile (USNM 86850, as Polyodontes sp. A by Wolf, 1984).

WEST INDIES. Puerto Rico, San Juan, Interstate Electronic Corp. sta 004–006, 25 Feb 1980, 18°30′27″N, 66°109′12″W, 259 m, juvenile (USNM 98806).

TYPE MATERIAL.—Holotype incomplete, with 39+ segments, 26+ mm long, 8 mm wide with setae. Largest paratype complete, with 57 segments, last 2 very small, 47 mm long, and 8 mm wide.

DESCRIPTION.—Body elongate, flattened dorsoventrally, tapered slightly anteriorly and more so posteriorly. Elytra delicate, smooth, oval, first 2 pairs covering prostomium, rest leaving middorsum uncovered, attached eccentrically to elytrophores near lateral side, with shallow lateral pocket beginninig with 4th elytra on segment 7 (Figure 42C–F).

Bilobed prostomium with pair of small rounded colorless ommatophores on anterior part of wider prostomium, with some scattered pigment spots but without distinct posterior eyes; median antenna with short ceratophore on middle of prostomium, with style longer than prostomium; lateral antennae inserted slightly ventral on anterior part of ommatophores, about as long as median antenna, fully visible dorsally; palps very long, smooth, tapered, extending to tip of fully extended pharynx. Tentacular segment distinct dorsally; tentaculophores lateral to prostomium, each with 2 acicula, small bundle of capillary setae, and pair of dorsal and ventral tentacular cirri, longer than antennae (Figure 42A,B,G).

Second segment with first pair of elytrophores, long ventral buccal cirri, similar to but shorter than tentacular cirri, and biramous parapodia; notopodium short, digitiform, with small bundle of long, finely spinous, capillary notosetae; neuropodium with rounded presetal and postsetal lobes and anteroventral bract; neurosetae numerous, long, slender, spinous, tapering to capillary tips (Figure 42A,B,H–J). Ventral mouth enclosed in segments 1–3 (Figure 42B). Distal border of extended pharynx with 15 pairs of papillae, lateral pairs very small and easily overlooked; middorsal one very long and tapered, midventral one only slightly longer than lateral ones; 2 pairs of hooked jaws each with 7–12 lateral teeth.

Third segment with dorsal cirri with short cirrophores and subulate styles, inflated basally, about same length as ventral cirri, both extending to tips of neurosetae; notopodium small, rounded, with few notosetae; upper and lower neurosetae similar, long, lanceolate, spinous, with capillary tips; middle neurosetae stout, acicular, with tips blunt, hairy, aristate (Figure 42K–N). Parapodia of segment 8 with short dorsal and ventral cirri, without notosetae; neurosetae similar to those of more anterior parapodia (Figure 43A–D).

Beginning with segment 9, notopodium wide, rounded, flattened, on dorsoanterior half of neuropodium, with notoaciculum and spinning glands, without notosetae; neuropodium with rounded presetal acicular lobe, anteroventral bract, and truncate postsetal lobe; three groups of neurosetae: lower group, within anteroventral bract, numerous, curved, lanceolate, with larger spines basally and small close-set spines on tapering capillary tips; middle group stout, acicular, with tips blunt, aristate, hairy distally and subdistally along one side; upper group, emerging from low anterodorsal bract hidden by notopodium, of 2 types: (a) few (3–6), long, slender, with brush-like tips; (b) more numerous, short, slender, with widely spaced spines and tapered tips (Figure 43E–O). Dorsal cirri subulate, inflated basally, ventral cirri tapering, both short, about equal in length (Figure 43F,K). Without parapodial branchiae.

JUVENILES (Figures 44–46).—Three juveniles are provisionally referred to this species, 2 from the Gulf of Mexico with 27+ and 43+ segments, 10+ and 19+ mm long, 5.5 and 6 mm wide with setae; a smaller juvenile from Puerto Rico with 35+ segments, 8+ mm long and 3 mm wide. The elytra are large, oval, nearly covering the dorsum, with large lateral pockets (Figure 44D–F). The prostomium differs from the adults in having rounded pigmented ommatophores and small eyespots in line with the ceratophore of the median antenna (Figures 44A, 46A). The pharynx has 13 pairs of border papillae, the middorsal one extra long and tapering, the midventral one not extra long; the jaws each have 5–8 lateral teeth (Figure 44B,C). The anterior parapodia of segments 2 to 8 are similar to the adults (Figures 44G–K, 45A–D). Beginning with segment 9, the parapodia have the spinning glands and the neurosetae characteristic of the adults (Figures 45E–N, 46B–F).

ETYMOLOGY.—The species is named for the collecting ship, R/V Alaminos.

DISTRIBUTION.—Gulf of Mexico, Puerto Rico. In 338–752 m for adults, 49–259 m for juveniles.

Acoetes Audouin and Milne-Edwards, 1832:435–437. [Type-species: Acoetes pleei Audouin and Milne-Edwards, 1832, by monotypy. Gender: feminine.]

Eupompe Kinberg, 1855 [1856]:387. [Type-species: Eupompe grubei Kinberg, 1855 [1856], by monotypy. Gender: feminine.]

DIAGNOSIS.—Prostomium bilobed, with pair of bulbous stalked ommatophores directed anteriorly and pair of small eyes; median antenna with ceratophore in middle of prostomium, lateral antennae inserted ventrally below ommatophores, with tips visible dorsally; pair of long palps, smooth or papillated. First or tentacular segment distinct dorsally; tentaculophores lateral to prostomium, each with 2 acicula, 2–4 groups of capillary setae and pair of tentacular cirri. Second segment with first pair of elytra and long ventral buccal cirri; biramous parapodia with bundle of notosetae; neurosetae slender, spinous, lanceolate. Acicular neurosetae from segment 3. Elytra on segments 2, 4, 5, 7, continuing on alternate segments. Dorsal cirri with short cirrophores and short styles on nonelytragerous segments; ventral cirri short, subulate. Notopodium from segment 9 wide, flattened, anterodorsal to neuropodium, with notoaciculum, internal spinning glands, and small row of delicate notosetae; neuropodium with lower group of neurosetae within anteroventral bract, neurosetae curved, spinous, lanceolate; middle row of stout acicular neurosetae, with or without aristae; upper group of neurosetae, emanating from low anterodorsal bract (hidden by notopodium), of 2 types: (a) longer, abruptly tapered to slender spinous tips, long spines subdistally and short spinous rows basally, (b) short (hidden by notopodium), bipinnate. With or without parapodial branchiae. Distal border of large muscular pharynx with 13–15 pairs of papillae, middorsal and midventral ones on wide lobulated bases, middorsal one longer than others; 2 pairs of hooked jaws, each with 5–9 lateral teeth.

The genus includes 12 species (plus 4 synonyms), of which 4 are new and 7 new combinations (one a doubtful species).