Leitoscoloplos geminus Mackie, 1987

Leitoscoloplos geminus Mackie, 1987 View in CoL

Figures 12–13 View FIGURE 12 View FIGURE 13

Scoloplos kerguelensis: Monro 1936: 160 View in CoL (in part). Not McIntosh 1885. Fide Mackie 1987. Leitoscoloplos kerguelensis: Hartmann-Schröder 1986: 82 View in CoL ; Hartmann-Schröder & Rosenfeldt 1988: 53 (in part); 1990: 105– 106 (in part).

Leitoscoloplos geminus Mackie, 1987: 6 View in CoL –7, fig. 5.

Material examined. Ross Island, McMurdo Sound, off McMurdo Station, 77°51.067′S, 66°39.880′E, 20 m, in sand and silt, coll. S. Kim and J.A. Blake, 11 Jan 2000, (11, LACM-AHF Poly 8957); same location GoogleMaps , 30 m, in sponge mat, coll. S. Kim and J.A. Blake, 15 Jan 2000 (3, LACM-AHF Poly 8958).—Antarctic Peninsula, Hero Sta. 1120 , 25– 31 m (45, USNM 187514 About USNM ); Gamma Island , Staten Island Sta. 32-63, coll. W.L. Schmitt , 100 m (1, USNM 46389 About USNM ); Anvers Island , Staten Island Sta. 67-63, coll. W.L. Schmitt , 62 m (5, USNM 46390). — South Shetland Islands, Hero Sta. 721-726 (2, USNM 60170 About USNM ) ; Sta. 721-742 (6, USNM 60169); Sta. 721-752 (3, USNM 60173); Sta. 721-819 (2, USNM 60171); Sta. 721-965 (2, USNM 60165); Sta. 721-968 (1, USNM 60159); Sta. 721-972 (2, USNM 60158); Sta. 721-975 (3, USNM 60160); Sta. 721-979 (1, USNM 60161); Sta. 721-980 (2 USNM 60168); 721-981 (1, USNM 60163); Sta. 721-983 (7, USNM 60162); Sta. 721-1033 (1, USNM 60164).—Bransfield Strait, Eltanin Sta. 12-1003, 210– 220 m (1, USNM 56522).

Description. A moderate-sized species, up to 28 mm long, 1.5 mm wide for about 85 setigers; average size 25 mm long, 1.2 mm wide for about 65 setigers. Color in alcohol: light tan; color in life: yellow to orange, with light brown pigment around mouth opening (based on personal observations at McMurdo Station, 19 Jan 2000). Thoracic region inflated, not depressed, with 10 setigers ( 7–9 in juveniles), wider than abdominal segments ( Figs. 12 View FIGURE 12 A, 13A); transition from thorax to abdomen abrupt ( Figs. 12 View FIGURE 12 A, 13A).

Prostomium short, narrow, conical, blunted on tip, not acute ( Figs. 12 View FIGURE 12 A, 13A–B); two nuchal slits in dorsolateral locations ( Fig. 13 View FIGURE 13 B) without eyespots. Peristomium a single achaetous ring, at least twice as wide as long, longer than setiger 1 ( Fig. 12 View FIGURE 12 A).

Thoracic parapodia similar, inconspicuous, with basal cushion from which setae arise; with triangular-shaped notopodial postsetal lobes and more oval-shaped neuropodial postsetal lobes increasing in size along thorax ( Fig. 12 View FIGURE 12 B). Abdominal notopodial postsetal lobes wide basally, tapering to elongate narrow tip ( Figs. 12 View FIGURE 12 C–D, 13C). Neuropodia short, rounded, expanded apically, with small notch from which setae arise; small subpodial flange present ventral to neuropodium, separated by a notch ( Fig. 12 View FIGURE 12 C); in more posterior setigers, a large, blister-like subpodial swelling usually present ventral to neuropodium ( Fig. 12 View FIGURE 12 D).

Branchiae from setiger 11–12 ( 10 in juveniles), usually 11, very short, inconspicuous; branchiae short, triangular at first ( Fig. 12 View FIGURE 12 C), becoming asymmetrical and irregular in shape in posterior segments ( Fig. 12 View FIGURE 12 D), usually bending medially.

Thoracic setae crenulated capillaries; notosetae arising from single spreading fascicle consisting of two rows, with shortest and thinnest setae in anterior row; neurosetae arising from two fascicles more or less dorsal and ventral to postsetal lobe ( Fig. 12 View FIGURE 12 B); setae of upper fascicle often with dark bases. Abdominal notosetae including crenulated capillaries and 0–2 furcate setae; furcate setae with unequal tynes connected by row of very fine needles as interpreted in light microscopy ( Fig. 12 View FIGURE 12 E); with SEM, individual needles appearing thicker and fewer; tynes with apical openings ( Fig. 13 View FIGURE 13 E). Anterior abdominal neurosetae long, stiff, becoming thinner, posteriorly.

Pygidium a simple ring, lacking cirri ( Fig. 13 View FIGURE 13 D).

Remarks. See comparative remarks under Leitoscoloplos mawsoni .

Distribution. Widespread in shallow Antarctic seas: Ross Sea, McMurdo Sound; South Orkneys, Antarctic Peninsula; South Shetland Islands; 20– 220 m.