Leanira robusta Verrill 1885

Leanira robusta Verrill

Leanira robusta Verrill, 1885a, p. 682, pl. 40: fig. 175; 1885b, p. 426.—Hartman, 1942, p. 104, fig. 8a; 1965a, p. 51.

Leanira hystricis.—Pettibone, 1963, p. 53 (part). [Not Ehlers, 1874.]

MATERIAL EXAMINED.—Off Martha's Vineyard, Massachusets, 220 meters, Fish Hawk station 876, 13 September 1880—2 syntypes (USNM 10320), 5 small syntypes (USNM 10323).

DESCRIPTION.—The length is more than 100 mm, the maximum width 10 mm, including setae, with segments more than 100. The elytra are thin, transparent, and found on all segments from 27 posteriorly; they are small and oval on the first few segments, become progressively larger, and subrectangular to subcordiform in shape, with lateral indentations (Figure 5m,n).

The oval prostomium and tentacular segment (I) are partially fused (Figure 5a–d). The short subulate median antenna is attached to an indistinct ridge on the anterior third of the prostomium; similar lateral antennae are attached to the inner dorsal sides of the tentacular parapodia, connected by indistinct ceratophores to the prostomium. Eyes and nuchal organs were not observed. The palps extend to about segment 14. The inner palpal sheaths are large and subtriangular, the outer ones, short and rounded. Medial to the inner palpal sheaths is a bulbous facial tubercle. The tentacular cirri have distinct cirrophores; the dorsal tentacular cirri are about twice as long as the ventral ones. There are usually 2 or 3 short stylodes medial to the cirrophores of the dorsal tentacular cirri; two bundles of capillary setae are directed anteriorly. The lateral lips lack distinct labial lobes (Figure 5b). The notopodia of segments 2 and 3 have a circlet of stylodes; the neuropodia have upper and lower groups of stylodes; the buccal cirri of segment 2 and the ventral cirri of segment 3 are short, thick and subconical; the neurosetae are similar to those of the following segments; both dorsal cirri and dorsal tubercles are lacking on segment 3 (a minute papilla may or may not be present; Figure 5e,f).

Branchiae are present from about segment 30, with smaller rudimentary ones more anteriorly. The parapodial ctenidia begin at about the same region as the branchiae; they are low and wide, the 3 ctenidia per parapodium appearing nearly contiguous (Figure 5j,k).

The notopodia and neuropodia are subequal in length (Figure 5g–k). The small clavate notopodia have circlets of stylodes on subterminal posterodorsal bracts and a larger terminal stylode near the tips of the acicular lobes. The notosetae are slender, coarsely to finely spinous, and taper to capillary tips. The large neuropodia have large posterior-upper and small posterior-lower bracts, both equipped with stylodes; the latter are filiform and numerous all along the body; in the neuropodia of the middle region, the posterior-upper bracts are extended anteriorly such that a few presetal stylodes are found (Figure 5k). The acicular lobes are subconical with inconspicuous anteroventral bracts. Most of the neurosetae are compound; the blades are canaliculate, and taper to fine tips; those of the lower series are more slender (Figure 5i). A few slender, simple spinous neurosetae occur in the upper parts of the neuropodia, beginning in the middle parapodia or more anteriorly (Figure 5l). The ventral cirri are slender, tapered, and do not extend to the distal tips of the neuropodia; small bulbous lobes are found on the outer bases of the cirri.

DISTRIBUTION.—Northwestern Atlantic, off Massachusetts. In 183 to 230 meters.