Sthenelais helenae Kinberg 1856

Sthenelais helenae Kinberg

Sthenelais helenae Kinberg, 1855:387; 1858:27, pl. 8: fig. 36A–H.—Hartman 1949:35, pl. 5: fig. 1, pl. 6: figs. 1–5. Conconia caerulea Schmarda, 1861:150, text-figure, pl. 37: fig. 319.

Sthenelais coerulea [sic].—Quatrefages 1865:279.—Ehlers 1901:56, pl. 4: figs. 14–16, pl. 5: figs. 1–5.—Monro 1933:17.

Sthenelais trivittata Grube, 1875:75, 77.

Sthenelais maculata Hartman, 1939:64, pl. 15: figs. 176–187.—Hartmann-Schroder, 1965:84, figs. 31–35.

MATERIAL EXAMINED.—Valparaiso, Chile, 11–15 meters, Eugenie Expedition—7 syntypes of Sthenelais helenae (NRS 381).

Valparaiso, Chile, McIntosh collection (as S. trivittata Grube)—1 specimen (BMNH 1921:5:1:617).

Chile (identified by Ehlers, 1901, as Sthenelais coerulea): Iquique, 15 meters, Ringe, collector—3 specimens (ZMH 610; USNM 43556); Taltal, 18 meters, Paessler, collector—2 specimens (ZMH 609); Valparaiso, Museum Godefroy—1 specimen (ZMH 611); Talcahuano, 9 meters, Paessler, collector—1 specimen (ZMH 3781); Lota, Concepción province, 15 meters, Michaelsen, collector—1 specimen (ZMH 5799).

Bay of Talcahuano, Chile, mud bottom, Captain Piening of the Padua, collector (identified by H. Augener as S. coerulea)—2 specimens (ZMH 11475).

Peru, Independencia Bay, 15 meters, sand and shell, Velero station 833–38, 10 February 1938—syntype of Sthenelais maculata (AHF).

Galapagos, James Island, James Bay, 9–11 meters, clean sand and algae, C. Crossland, collector (as S. coerulea by Monro)—1 small specimen (BMNH 1932:12:24:251).

DESCRIPTION.—Length up to 110 mm, width 3 to 6 mm, including setae, segments numerous (about 200). Wide middorsal ridge on segments 2–5, with three pairs of small ctenidia alongside (Figures 1a, 3a). Elytra thin, transparent to opaque, suborbicular, subrectangular to subreniform. Anterior elytra with uniformly distributed microtubercles and lateral borders with papillae; microtubercles low, rounded to subconical (Figures 1h, 3k,l). More posterior elytra with microtubercles confined to anterior and medial regions, sometimes few submarginal papillae near lateral papillate borders (Figures 1i, 3m,n). Elytra mottled with dark pigment, sometimes darker rings around region of elytrophores (Figure 3k–n).

Prostomium with median antenna with large lateral auricles on ceratophore and moderately long tapered style; lateral antennae short, subulate; four eyes arranged in square, rather small, anterior pair larger than posterior pair; palps extending about to segment 7 (6–8); nuchal organs partially hidden by dorsal ridge and first pair of ctenidia (Figures 1a–c, 3a). Tentacular parapodium with dorsal tentacular cirrus slightly shorter than median antenna; ventral tentacular cirrus about half as long as dorsal cirrus; inner tentacular lobe extending beyond ventral tentacular cirrus, fused to shorter, rounded inner palpal sheath; dorsal ctenidium elongate-oval (Figures 1a–d, 3a).

Parapodia of segments II and III directed anteriorly, slightly modified from following segments, with pair of small ctenidia on lateral lips (Figures 1a,b,e,f; 3b,c). Blades of compound falcigerous neuroseta with 1–4 articles, with bifid tips, stems with numerous spinous rows (6–30); lower neurosetae more slender than middle and upper ones (Figures 1g, 3d). Few upper simple spinous neurosetae beginning on segment III (Figure 2e). Additional small ctenidia located medial to elytrophores of segment II (Figure 1a) and medial to ventral cirri of segments III–VII (Figure 1b).

Parapodia of anterior (Figures 2a–d, 3e,f) and middle regions (Figure 2i,j) similar. Cirriform branchiae beginning on segment IV (Figure 2a). Notopodial bracts fimbriated, lower anterior papillae longer than dorsoposterior ones. Neuropodial acicular lobes usually with bulbous stylodes (1–3 on segments II–IV, 2–0 on following segments). Upper lobes of bilobed posterior bracts with several stylodes on upper anterior part. Anteroventral and anterior upper bracts fimbriated—with row of long papillae. C-shaped group of stout neurosetae with blades short to longer, with 1–3 articles; stems smooth or with faint spinous rows (Figures 2g, 3i). Upper anterior group of neurosetae simple spinous (Figures 2e, 3g) and compound falcigerous with blades of 3 articles and stems with few spinous rows (Figures 2f, 3h). Blades of anteroventral slender neurosetae with 1–4 articles; stems with 2–5 spinous rows (Figures 2h, 3j). Ventral cirri with basal knob and more or less distinctly inflated more distally.

DISTRIBUTION.—Chile to western Mexico, Galapagos Islands. Littoral to 140 meters.