Acoetes mohammadi Pettibone 1989

Acoetes mohammadi

Panthalis melanonotus.—Mohammad, 1973:24. [Not Panthalis melanonotus Grube, 1876.]

MATERIAL EXAMINED.—ARABIAN GULF. Hawalli, Kuwait, near low tide mark, M. Mohammad, collector, holotype (BMNH 1971.40, as Panthalis melanonotus by Mohammad, 1973).

DESCRIPTION.—Holotype with 39+ segments, 25+ mm long, 10 mm wide with setae. Elytra large, oval, delicate, leaving middorsum uncovered, some with outer margin rolled dorsally, with small areolae on medial part and flecks of dark pigment on surface (Figure 60C,D). Prostomium bilobed, oval, with pair of bulbous ommatophores with distinct neck; ceratophore of median antenna on middle of prostomium, continuing posteriorly as raised ridge, with tapered style projecting slightly beyond ommatophores; lateral antennae inserted ventral to ommatophores with only tips visible dorsally; posterior pair of small sessile eyes lateral to ridge of median antenna, with few pigment spots nearby; ventral palps stout, tapering, about 1.5 times length of prostomium, covered with minute papillae and irregularly banded with black pigment (Figure 60A). Tentacular segment visible dorsally forming raised occipital fold with groups of papillae on lateral sides; tentaculophores lateral to prostomium, each with few capillary setae, dorsal and ventral tentacular cirri slightly longer than median antenna, with scattered pigment spots (Figure 60A).

Second segment with first pair of elytrophores, ventral buccal cirri longer than following ventral cirri, and biramous parapodia; notopodium smaller than neuropodium, bilobed, with digitiform acicular lobe and shorter, rounded lower part, with numerous slender, capillary, finely spinous notosetae forming radiating bundle as long and large as neurosetae; neuropodium with conical presetal acicular lobe, postsetal lobe flared, bilobed on right side, entire on left side, with well-developed ventral bract; numerous long, slender neurosetae, wider basally, finely spinous, with capillary tips (Figure 60A,E-G). Distal border of extended pharynx with 15 dorsal papillae, middle one on wide base, tapered, much longer than others, and 12 ventral papillae, midventral one with wide base but without distinct papilla; 2 pairs of claw-like jaws without lateral teeth (perhaps worn) (Figure 60B).

Third segment with first pair of dorsal cirri with short cirrophores and styles extending to tips of setae; ventral cirri about as long as dorsal cirri; parapodium smaller than on second segment, with smaller bundle of long capillary notosetae; neuropodium with truncate postsetal lobe and ventral bract; middle aristate neurosetae somewhat modified, tapering gradually to spinous distal tips; lower neurosetae, within ventral bract, wider basally with longer spines, tapering to capillary tips with short close-set spines (Figure 60A,H-K). Following parapodia of segments 4 to 8 similar (Figure 60L-N).

From segment 9 on, parapodia larger, with notopodium rounded, flattened, on anterodorsal half of larger neuropodium, with notoaciculum, spinning glands, and few short notosetae emerging from inner side of notopodium; neuropodium with wide conical presetal acicular lobe, truncate postsetal lobe, and more or less distinct anteroventral bract; lower neurosetae, within anteroventral bract, numerous, similar to neurosetae of more anterior parapodia; middle neurosetae stout, acicular, with or without aristae, some in more posterior parapodia with subdistal spines on one side; upper group of neurosetae, emanating from low dorsoanterior bract, hidden from view unless notopodium pulled back, of 2 types: (a) longer, slender, tapering abruptly to slender tip, with subdistal long bushy hairs and short spinous rows more basally; (b) shorter, slender, bipinnate, hidden by notopodium (Figure 61A-J). Few bulbous branchiae, beginning about segment 10, on bases of dorsal cirri and elytrophores (Figure 61B,G). Thin-walled branchial areas medial to ventral cirri.

TUBE.—According to Mohammad, the collector, the animal was found in a membranous tube coated with a very thick layer of mud.

ETYMOLOGY.—The species is named for M.-B.M. Mohammad, the collector of the holotype and specialist on the polychaetes in the Arabian Gulf.

DISTRIBUTION.—Arabian Gulf. Intertidal.