Leitoscoloplos lunulus, Blake, 2020

Blake, James A., 2020, New species and records of deep-water Orbiniidae (Annelida, Polychaeta) from the Eastern Pacific continental slope, abyssal Pacific Ocean, and the South China Sea, Zootaxa 4730 (1), pp. 1-61 : 12-15

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Leitoscoloplos lunulus

new species

Leitoscoloplos lunulus new species

Figures 5–6 View FIGURE 5 View FIGURE 6


Leitoscoloplos sp. 1: Hilbig & Blake 2006: 265.

Material examined. Continental slope off northern California, off Half Moon Bay , U.S EPA 102 Site selection

Survey, R / V Point Sur, coll. J.A. Blake, south of Pioneer Canyon, Sta. 4-8. 18 Sep 1991, 37°13.85′N, 123°13.50′W, 1560 m, holotype ( LACM-AHF Poly 11660) GoogleMaps ; north of Pioneer Canyon , Sta. 3-4, 14 Sep 1991, 37°27.83′N, 123°11.60′W, 1030 m, 1 paratype in two pieces ( LACM-AHF Poly 11661) GoogleMaps ; Sta. 3-7, 14 Sep 1991, 37°27.44′N, 123°19.50′W, 1675 m, 1 paratype ( CASIZ 234041 ) GoogleMaps ; Sta. 3-16, 15 Sep 1991, 37°23.20′N, 123°14.44′W, 1220 m, 1 paratype ( CASIZ 234048 ) GoogleMaps .

Description. A small species, holotype (LACM-AHF Poly 11660) complete, with 50 setigers, 6.8 mm long, 0.45 mm wide across thoracic segments; paratype from Sta. 3-4 (LACM-AHF Poly 11661), smaller, mostly complete, with 34 setigers, 4.1 mm long. Body thickened in thoracic region with smooth rectangular-shaped segments about 4.6 times wider than long; abdominal segments becoming narrower and shorter. Thoracic segments uniannulate with narrow intersegmental groove ( Fig. 5A View FIGURE 5 ); abdominal segments becoming biannulate due to narrow ring developing on posterior segmental margin. Dorsal and ventral longitudinal ridges or grooves absent. Color in alcohol: light tan.

Pre-setiger region short, compact, slightly wider than long, longer than first two setigers ( Fig. 5 View FIGURE 5 A–B). Prostomium semi-circular in shape, narrowing to broadly rounded apex in dorsal and ventral views ( Fig. 5 View FIGURE 5 A–B); narrower in lateral view ( Fig. 5C View FIGURE 5 ); eyespots absent; nuchal organs elongate lateral opening on posterior margin ( Fig. 5C View FIGURE 5 ). Peristomium appearing entire in dorsal view ( Fig. 5A View FIGURE 5 ); with single ventrolateral groove ( Fig. 5 View FIGURE 5 B–C). Anterior margin sculpted especially on lower lip of mouth ( Fig. 5B View FIGURE 5 )

Thorax with nine setigers, abruptly changing to abdominal segments with development of elongated neuropodium and loss of most neurosetae ( Fig. 5A View FIGURE 5 ). Thoracic notopodial and neuropodial postsetal lamellae both elongate, digitiform, tapering to narrow apex; arising from broadly rounded base ( Fig. 5E View FIGURE 5 ). Abdominal notopodia short, triangular, with long, thin, digitiform postsetal lamella ( Fig. 6 View FIGURE 6 A–B). Abdominal neuropodia thickened lobes, short at first surrounded by thick basal flange ( Fig. 6A View FIGURE 6 ); subsequent neuropodia long, narrow, with low subpodial flange on body wall below neuropodial base ( Fig. 6B View FIGURE 6 ); subpodial papillae absent. Neuropodia with rounded apex and short, narrow ventral cirrus with rounded tip ( Fig. 6 View FIGURE 6 A–B).

Branchiae from setiger 14 in holotype and setigers 14–15 in paratypes. Branchiae full size from initiation, weakly triangular at first, tapering to rounded tip ( Fig. 6A View FIGURE 6 ); branchiae of middle and posterior setigers thicker, more fleshy in appearance with expansion, narrowing to papillate tip ( Fig. 6B View FIGURE 6 ). Each branchia as long as or slightly longer than notopodial postsetal lamella.

All setae camerated capillaries except neuropodial aciculae; furcate and flail setae absent. Thoracic noto- and neurosetae long, crowded capillaries numbering about 14–16, arranged in two weakly defined rows. Abdominal notosetae include 7–8 capillaries, some long; abdominal neurosetae include 4–5 capillaries and 1–2 short, narrow protruding pointed aciculae.

Pygidium with two dorsal, four lateral, and one large ventral lobe surrounding anal opening. Two thin, digitiform anal cirri arising from dorsal lobes ( Fig. 5D View FIGURE 5 ).

Methyl Green stain. No pattern, body stains uniformly and de-stains rapidly.

Remarks. Leitoscoloplos lunulus n. sp. is another member of the L. kerguelensis group as defined by Blake (2017) in having branchiae first present from an anterior abdominal setiger. L. lunulus n. sp. is one of five species in the eastern Pacific belonging to this group and as noted in the previous account, is most closely related to L. gordaensis n. sp. by lacking furcate setae and having a short pre-setiger region where the prostomium is distinctly separated from the peristomium by a groove. In L. lunulus n. sp. the groove that separates the prostomium and peristomium is sculpted rather than smooth and the thorax has nine setigers instead of ten.

Etymology. The epithet is from the Latin, lunula, for moon, in relation to the survey location off Half Moon Bay, California.

Distribution. Off northern California, middle continental slope depths, 1020–1760 m.


Departamento de Geologia, Universidad de Chile


Royal British Columbia Museum - Herbarium












Leitoscoloplos lunulus

Blake, James A. 2020


Hilbig, B. & Blake, J. A. 2006: 265
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