Leodamas verax Kinberg, 1866

Blake, James A., 2017, Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America, Zootaxa 4218 (1), pp. 1-145 : 60-62

Leodamas verax Kinberg, 1866

Figures 25–26

Leodamas verax Kinberg, 1866: 252 .

Scoloplos (Leodamas) verax: Hartman 1948: 104 –105, pl. 15, figs. 3–4; 1957: 286, pl. 31, figs. 1–4.

Material examined. Uruguay, IBM Sta. N-254, 27– 30 m (1, USNM 1013643 ) ; IBM Sta. N-1071, 36– 42 m, sand and shells (1, USNM 1013642). — Argentina, IBM Sta. 2287 (R/ V A. Saldanha), 38°05′S, 56°43.5′W, 67 m, (1, USNM 1013644 ) . — Argentina, intertidal collected by J.M. Orensanz: Bahía de San Blas, north of Riacho Jabali , Oct 1968 (1, JAB); NE of Isla Jabali, intertidal , Apr 1970 (3, 21, and 15 specimens USNM 1013646–8); Riacho Jabali, intertidal, muddy sand, Oct 1968 (17, USNM 1013652 ); Bahía de San Antonio, oeste, Marejada norte. coll. R. Olivier and J.M. Orensanz , 6 Feb 1971, intertidal (15, USNM 1013655); 8 Feb 1971, intertidal (1, USNM 1013656); 9 Dec 1971, intertidal (1, USNM 1013650); 11 Dec 1972, intertidal (3, USNM 1013653); Golfo San Matías, IBM Sta. SAO-III-1 0 41, intertidal, sandy gravel, 1972, neotype (USNM 1013645); Las Grutas, intertidal, under mussel bed, 7 Feb 1971, coll. J. Escofet and J.M. Orensanz (7, USNM 1013651).

Description. A large species, up to 15 cm long, 2.8 mm wide, for 340 setigers. Color in alcohol: light tan to flesh colored, sometimes with dusky pigment patch in middle of prostomium.

Body dorsoventrally flattened in thoracic region, rounded in abdominal region; thoracic region with 22–24 setigers, last of which is transitional; peristomial segment and all setigerous segments readily distinct from one another; individual segments without additional annulations ( Fig. 25 A). Branchiae from setiger 5–6, continuing to end of body; each branchia broad basally, tapering distally ( Fig. 25 A–C).

Prostomium triangular in shape, bluntly pointed on anterior margin; proboscis saclike, with numerous lobes ( Figs. 25 A, 26A); peristomium with one simple achaetous ring, prominent anterolateral nuchal slits present ( Fig. 26 A, inset); eyespots absent ( Fig. 25 A).

Thoracic parapodia well developed, with conspicuous branched notopodial lamellae ( Fig. 25 A–B) and numerous golden neuropodial uncini. Notopodia with single notopodial lamella to setiger 2–6, becoming double, then triple or quadruple from about setiger 4–16 ( Fig. 25 A–B); branched notopodia sometimes continuing on first or second abdominal setiger. Neuropodia of thoracic setigers 1–20 without lobes or lamellae ( Fig. 25 B), from setiger 21–22 or transition to abdominal region, a single ventral cirrus and sometimes a second ventral cirrus (or subpodial lobe) present; these continuing into abdominal region ( Fig. 25 C).

Abdominal parapodia all similar, lacking interramal cirri; ventral cirrus present to about setiger 65 ( Fig. 25 C), second ventral cirrus (or subpodial lobe) sometimes present from about setigers 31–40; notopodial postsetal lamella of last few thoracic setigers continuing through abdominal region.

Notosetae including fascicles of crenulated capillaries in thoracic and abdominal notopodia; 1–3 furcate setae in posterior thoracic and abdominal notopodia; 1–2 straight, tapering notopodial spines in abdominal notopodia with furcate setae and capillaries ( Fig. 26 E); in light microscope furcate setae with unequal tynes, connected by membrane consisting of fine needles ( Fig. 25 F); in SEM, furcate setae with 11–12 delicate needles on each side with apical needles merging with tynes ( Fig 26 F), tynes with minute openings in tips, shafts with transverse rows of fine barbs ( Fig. 26 F).

Thoracic neuropodial uncini arranged in three long vertical rows and one shorter posterior row curving ventrally under rows 1–3 ( Fig. 26 B–C); uncini golden in color, thick, blunt-tipped, with lateral groove or notch, some with dark internal core ( Fig. 25 D–E); in SEM subterminal groove present on convex side and with elongate shaft bearing weakly developed transverse ribs ( Fig. 26 D); capillaries entirely lacking. Abdominal neuropodia with 1–2 projecting aciculae ( Figs. 25 G, 26G) and fascicle of delicate capillaries ( Fig. 25 C).

Pygidium short, bulbous, with anus directed dorsally, surrounded by lobed border bearing two pair of tapering anal cirri.

Remarks. Leodamas verax was described by Kinberg (1866) from depths of 62 m off southeastern South America. In that paper, Kinberg established the genus Leodamas , with L. verax as the type species. The species has gone unreported since its original description, although Hartman (1948; 1957) redescribed the holotype which was archived in the Swedish Museum. Subsequent to Hartman’s examination, the holotype appears to have been lost; curators at the Swedish Museum have not been able to locate the specimen. I also requested a search of the collections at the Allan Hancock Foundation, on the possibility that Hartman might have inadvertently retained the holotype in her research collections, but the type was not located there. Because of the importance of L. verax to the nomenclature of the genera Scoloplos and Leodamas , a neotype has been designated from among the abundant new material from Argentina to replace the lost holotype (USNM 1013645).

Leodamas verax is closely related to L. dendrocirrus described by Day (1977) from Australia (NSW) in 65 m which also has branched notopodia. L. verax has 22–24 thoracic setigers instead of 17–18; capillaries are absent in thoracic neuropodia of L. verax and present in L. dendrocirrus ; the thoracic neuropodial uncini of L. verax are generally smooth, weakly curved, blunt apically, notched on the convex side and with weak transverse ribs along the shaft; in L dendrocirrus , the uncini are more strongly curved, taper to a narrow tip, lack a notch, but have distinct transverse ribs on the convex side. Details may be found in Table 1. In addition, the thoracic neuropodial uncini of L. verax are arranged in 3 long vertical rows and with a 4th short posterior row that curves ventral to rows 1–3. This arrangement is similar to that of L. marginatus and several other species described in this study. Ledodamas verax is also the only member of the genus to have double ventral cirri present in the abdominal segments, although this feature has been observed only rarely. The new specimens agree very well with the description of the holotype provided by Hartman (1948, 1957), except that the bifurcate notopodial lobes reported by Hartman may actually consist of 2, 3, or 4 separate branches.

Distribution. Known only from off Uruguay and Argentina, intertidal to 62 m.

Figures

FIGURE 25. Leodamas verax (Kinberg, 1866). Neotype (USNM 1013645). A, anterior end, dorsal view; B, thoracic parapodium, posterior view; C, anterior abdominal parapodium, posterior view; D – E, thoracic neuropodial uncini; F, furcate seta; G, abdominal neuropodial acicula.

FIGURE 26. Leodamas verax (Kinberg, 1866). (USNM 1013651). A, anterior end, left lateral view, [inset of nuchal organ, not to scale]; B, thoracic neuropodial parapodia, lateral view; C, thoracic neuropodial parapodium, detail showing arrangement of uncini; D, thoracic neuropodial uncini, detail; E, abdominal neuropodial parapodium; F, furcate seta; G, abdominal neuropodial spine.