Malmgreniella hendleri Pettibone 1993

Malmgreniella hendleri

MATERIAL EXAMINED.—NORTHWEST ATLANTIC OCEAN: Panama: Caribbean Sea, Galeta Reef, G. Hendler, collector, on burrowing brittle stars: 28 Oct 1977, on disc of Ophionephthys limicola Lütken, holotype (USNM 133567); 10 Oct 1977, 9 m, on mouth of Amphiura cf. fibulata Koëhler, paratype (USNM 133570); 13–14 Sep 1978, 9–11 m, on A. cf. fibulata, young paratype (USNM 133569); 2–5 Oct 1980, 11 m, sand, on O. limicola, 7 paratypes (USNM 133568; LACM).

DESCRIPTION.—Holotype 6 mm long, 3 mm wide including setae, with 34 segments; paratypes 6–9 mm long, 2.5–3 mm wide, with 31–34 segments; young paratype 1 mm long, 1 mm wide, with 13 segments and budding area, with 7 pairs of elytra. Posterior fourth of dorsum with black pigment spots medial to elytrophores and dorsal tubercles, and 4 groups of spots on posterior fourth of ventrum (Figure 33B). Color lacking on young paratype. Elytra 14–15 pairs, large, covering dorsum, oval to subreniform, without papillae or microtubercles; color pattern forming nearly complete circle on 1st and 2nd elytra, on following elytra, pattern is C-shape on medial part of elytra, including spot on place of attachment to elytrophore (Figure 33C–E). Bilobed prostomium with anterior lobes truncate, without peaks, with light pigmentation on middle of prostomium; 2 pairs of eyes, larger anterior pair slightly anterior to greatest width of prostomium, smaller posterior pair near posterior border; median antenna with ceratophore in anterior notch, long style with filamentous tip; lateral antennae with ceratophores inserted terminoventrally, with short, subulate styles; palps stout, tapered, about same length as median antenna; tentaculophores with single seta on inner side, dorsal and ventral tentacular cirri similar to median antenna (Figure 33A). Second segment with first pair of elytrophores, biramous parapodia, and long ventral buccal cirri similar to tentacular cirri (Figure 33A). Extended pharynx with 9 pairs of border papillae and 2 pairs of hooked jaws.

Biramous parapodium with notopodium shorter than neuropodium, rounded, with projecting acicular lobe on lower side; neuropodium with subconical presetal acicular lobe, with bulbous supraacicular process; postsetal lobe shorter, rounded (Figure 33F,G). Notosetae numerous, forming radiating bundle, shorter and more slender than neurosetae, with faint spinose rows and slightly bulbous bare tips (Figure 33H). Neurosetae moderate in number (about 15), forming fan-shape bundle; supraacicular neurosetae with longer spinose regions, and more prominent spinose rows, with bifid, bare tips (Figure 33I); subacicular neurosetae with shorter spinose regions and entire, bare tips (Figure 33J). Dorsal cirri with cylindrical cirrophore, long styles with minute sensory papillae, tapering to slender tips and extending beyond tips of neurosetae; dorsal tubercles nodular; ventral cirri short, subulate (Figure 33G). Pygidium rounded, between posterior pair of small parapodia, with pair of long anal cirri.

BIOLOGY.—Malmgreniella hendleri was collected on two species of burrowing ophiuroids, Ophionephthys limicola Lütken and Amphiura cf. fibulata Koëhler, on Galeta Reef, Panama, by Gordon Hendler.

ETYMOLOGY.—The species is names for Gordon Hendler, specialist on the Ophiuroidea and collector of the polynoid commensals.

DISTRIBUTION.—Northwest Atlantic Ocean, Caribbean Sea, Panama. In 9–14 meters.