Comprehensive Description

provided by Smithsonian Contributions to Zoology
Fimbriosthenelais hobbsi

MATERIAL EXAMINED.—Siguanea Bay, Isle of Pines, Northwestern Caribbean, 4–8 meters, P. Bartsch, collector, Smithsonian-Roebling Exploring Expedition, station R-124, 11 April 1937—holotype (USNM 43553).

TYPE MATERIAL.—The holotype consists of an anterior fragment of 31 segments, 10 mm in length and 3 mm in width, including setae.

DESCRIPTION.—Wide middorsal ridge on segments 2–5, with 2 pairs of small ctenidia alongside (Figure 24a). Ventral surface thickly papillate with globular warts or papillae (Figure 24d). Elytra delicate, transparent, suborbicular, subrectangular to subreniform; lateral borders with papillae of variable lengths and tactile micropapillae; microtubercle-papillae of peculiar type (chitinous rounded tubercled bases continuous with tubular papillae and ending in rounded tips with sensory hairs) scattered throughout surface of first elytra and on posterior halves of following elytra (Figure 24i–k).

Prostomium with median antenna with small auricles and rather short style with bulbous tip; lateral antennae short, subulate; four eyes arranged in square, moderate and subequal in size, located lateral to ceratophore of median antenna; palps extending about to segment 9; nuchal organs inconspicuous (Figure 24a). Tentacular parapodia with dorsal tentacular cirri subequal to median antenna; ventral tentacular cirri slightly shorter than dorsal cirri; inner tentacular lobes shorter than ventral tentacular cirri, fused to shorter, rounded inner palpal sheaths; dorsal ctenidia elongate-oval (Figure 24a).

Parapodia of segments II and III directed anteriorly, slightly modified from following segments; with pair of ctenidia on lateral lips (Figure 24a,b). All neurosetae compound falcigerous; blades with 2–7 articles and bifid tips; stems with 2–4 spinous rows (Figure 24c). Additional small ctenidia located medial to elytrophores and lateral to ventral buccal cirri of segment II and medial to ventral cirri of segments III–VII (Figure 24a,b).

Parapodia of anterior region with cirriform branchiae beginning on segment VI (Figure 24d,e). Notopodial bracts with row of papillate stylodes on anterior side. Neuropodial acicular lobes with 2–3 papillate clavate stylodes. Truncate posterior bracts with row of papillate stylodes. Anteroventral and anterior upper bracts fimbriated—with rows of papillate stylodes. Neurosetae all compound falcigers with bifid tips, all similar, differing only slightly in length and size; blades of upper and lower neurosetae with 2–3 articles; blades of slightly stouter middle neurosetae with 2 articles; stems with 2–4 spinous rows (Figure 24f–h). Simple neurosetae not observed (at least to segment 31). Ventral cirri with only slight indication of small basal knobs.

ETYMOLOGY.—The species is named for Dr. Horton H. Hobbs, Jr., in appreciation for the help he has given me in working over some of my polychaete manuscripts.

DISTRIBUTION.—Caribbean (Isle of Pines). In 4 to 8 meters.
bibliographic citation
Pettibone, Marian H. 1971. "Partial revision of the genus Sthenelais Kinberg (Polychaeta: Sigalionidae) with diagnoses of two new genera." Smithsonian Contributions to Zoology. 1-40.