Leitoscoloplos cliffordi, 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 : 6-9

Leitoscoloplos cliffordi new species

Figures 1–2

urn:lsid:zoobank.org:act:B350ADD5-747F-4A5A-8B70-967C177A0FC4

Leitoscoloplos sp. 1 and sp. 5: Blake et al. 2009: Table B1 .

Material examined. Continental slope off northern California, west of Farallon Islands, SF-DODS Benthic Monitoring Program , Sta. 7, coll. 30 Oct 1997, 37°39.99′N, 123°28.00′W, 2820 m, holotype ( LACM-AHF Poly 11654) ; Sta. 2, 11 Dec 1996, 37°41.01′N, 123°29.90′W, 2600 m, paratype ( LACM-AHF Poly 11655) ; Sta. 10, 26 Sep 2003, 37°40.00′N, 123°30.98′W. 2736 m, 1 paratype ( CASIZ 234026 ) ; Sta. 16, 28 Aug 2016, 37°38.0111′N

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123°26.9950′W, 2753 m, 1 paratype ( CASIZ 234034 ); Sta. 23, 10 Dec 1996, 37°37.13′N, 123°29.08′W, 2950 m, paratype ( LACM-AHF Poly 11656); Sta. 27, 27 Jun 2015 , 37°41.0072′N, 123°32.0183′W, 2750 m, 1 paratype ( CASIZ 234035 ); Sta. 64, 25 Sep 2002 , 37°36.01′N, 123°33.01′W, 3136 m, 2 paratypes.( CASIZ 234030 ); Sta. 116, 13 July 2007 , 37°17.537′N, 124°09.192′W, 2908 m, 2 paratypes ( LACM-AHF Poly 11657) .

Non-type material. Sta. 2, 28 June 2015, 37°41.0060′N, 123°30.0152′W, 2560 1 specimen ( CASIZ 234042); Sta. 6, 22 Sep 2002, 37°40.02′N, 123°27.00′W, 2697 m, 1 specimen ( CASIZ 234053 ) ; Sta. 6, 15 Sep 2005, 37°40.004′N, 123°27.002′W, 2692 m, 1 specimen ( CASIZ 234049 ) ; Sta. 9, 30 Oct 1997, 37°40.04′N, 123°29.98′W, 2927 m, 1 specimen ( CASIZ 234043 ) ; Sta. 11, 28 Sep 2017, 37°38.9993′N, 123°30.9960′W, 3109m, 1 specimen ( MCZ 153559 ) ; Sta. 17, 24 Sep 2003, 37°38.05′N, 123°27.94′W, 2750 m, 1 specimen ( CASIZ 234050 ) ; Sta. 17, 27 Sep 2006, 37°37.960′N, 123°28.005′W, 2789 m, 1 specimen ( MCZ 153560 ) ; Sta. 17, 27 Sep 2017, 37°38.009′N, 123°27.9995′W, 2827 m, 2 specimens ( MCZ 153561 ) ; Sta. 23, 26 Sep 2002, 37°36.95′N, 123°29.02′W, 2954 m, 1 specimen ( CASIZ 234045 ) ; Sta. 27, 16 Oct 2000, 37°40.97′N, 123°31.98′W, 2740 m, 1 specimen ( CASIZ 234044 ) ; Sta. 57, 16 Oct 2000, 37°42.99′N, 123°32.99′W, 2650 m, 1 specimen ( CASIZ 234051 ) ; Sta. 92, 14 Sep 2005, 37°44.943′N, 123°34.825′W, 2819 m, 1 specimen ( MCZ 153562 ) ; Sta. 92, 21 Jun 2015, 37°45.0085′N, 123°35.0063′W, 2800 m, 1 specimen ( MCZ 153563 ) .— US Navy 103 Site Selection survey, R / V Wecoma Sta. B-5, 20 Jul 1991, 37°38.94′N, 123°28.81′W, 2925 m, 1 specimen ( CASIZ 234047 ) .

Description. A moderate-sized species, holotype complete, 20 mm long, 1.2 mm wide across thoracic segments and 0.75 mm across middle segments for about 90 setigers; paratypes all incomplete, up to 20 mm long and 1.7 mm wide across thoracic segments for approximately 90 setigers. Body elongate, with thoracic region widest, gradually narrowing posteriorly. Thoracic segments about twice as wide as long, each separated by distinct segmental groove dorsally elevated into an intersegmental transverse ridge producing a biannulate segmental pattern ( Figs. 1A , 2A ), best developed in large specimens, continuing on to anterior abdominal segments ( Fig. 2B , arrows); intersegmental groove not as well developed ventrally ( Fig. 2A ). Laterally and ventrally, abdominal segments develop a narrow intersegmental annular ring anterior to larger segmental ring continuing ventrally between neuropodia ( Fig. 2 B–C, arrows). Middle and posterior segments about twice as wide as long. Shallow mid-ventral groove present from anterior segments to near posterior end ( Fig. 2A ). Color in alcohol: light tan; holotype and large paratypes with dorsal brown pigment across middle and posterior segments.

Pre-setiger region about as long as first two setigers, triangular in shape, narrowing anteriorly ( Figs. 1A , 2A ). Prostomium triangular, narrowing to pointed apex ( Figs. 1A , 2A ); nuchal organs short oval slits on posterior lateral margin, eyespots absent. Peristomium composed of one achaetous ring, but with weakly developed lateral grooves sometimes evident ( Figs. 1A , 2A ), none crossing dorsum; posterior margin weakly extending on to setiger 1 ( Fig. 1A ).

Thorax with nine setigers followed by 1–2 transitional setigers; boundary between last thoracic and first abdominal setiger demarcated by loss of most neurosetae and increase in size of neuropodial lobe on setigers 10–12. Thoracic notopodial and neuropodial lobes digitiform, relatively short, both similar in form ( Fig. 1B ); abdominal notopodia of anterior abdominal segments becoming narrower, elongate ( Fig. 1C ); posterior notopodia shorter, thicker, rounded apically ( Fig. 1D ). Abdominal neuropodia thickened, with rounded terminal lobe and short ventral cirrus ( Fig. 1 C–D); without subpodial flange or papillae.

Branchiae first present from setiger 15 (rarely 16) as rudiments; gradually increasing in size; branchiae of middle abdominal segments becoming broad and flattened, about one-third longer than notopodial lobe ( Fig. 1C ); branchiae of posterior segments where parapodia shifted dorsally, shorter, thicker, sometimes with expanded tip ( Fig. 1D ).

Notosetae include camerated capillaries and furcate setae ( Fig. 1 C–E); about 30 capillaries in two loose rows in thoracic notopodia reduced to 7–8 long, thin, weakly barbed capillaries in abdominal segments. Thoracic neurosetae all capillaries with up to 35 in four rows, some specimens with long silky capillaries in first 4–5 setigers; abdominal neurosetae include 1–4 capillaries and 1–2 short protruding aciculae, these minute, with rounded apex ( Fig. 1D inset). Furcate setae of abdominal notopodia with unequal tynes, each tyne with a flattened rounded apex within which an opening and narrow channel can be observed with light microscope ( Fig. 1E ); narrow elongate fibrils present between tynes; flail setae absent.

Pygidium bluntly rounded, bearing two thin elongate cirri.

Variability. Most specimens were damaged to some extent and the most frequent problem was the lack of or damage to posterior segments and the loss or breakage of setae. Because of this, furcate setae were not observed on several specimens. However, the number of thoracic setigers was consistently nine and branchiae, when observed, generally began on setiger 15, sometimes 16. Later occurrences of branchiae were usually on damaged specimens. The prostomium was either narrower than figured ( Fig. 1A ) or wider and contracted. However, the general configuration was the same.

Methyl Green stain. Prostomium unstained, peristomium, light green; rest of body staining blue-green throughout, with no pattern, de-stains rapidly.

Remarks. Leitoscoloplos cliffordi n. sp. occurs throughout the SF-DODS sampling area, but is rare, with only 25– 30 specimens identified from approximately 207 0.1-m 2 box core samples collected over 16 years of monitoring. It is likely that the preferred habitat or depth of this species has not been discovered.

Leitoscoloplos cliffordi n. sp. and four eastern Pacific deep-water congeners, L. gordaensis n. sp., L. lunulus n. sp., L. pachybranchiatus , and L. williamsi n. sp. belong to the L. kerguelensis group in having branchiae first present from an anterior abdominal setiger ( Blake 2017). These species are separated from one another in the key and compared in Table 1 . Although differing from all of these species in having instead of lacking furcate setae in abdominal notopodia, L. cliffordi n. sp. is most similar to L. williamsi n. sp. in having an elongate, narrow pre-setiger region. The two species further differ in that L. cliffordi n. sp. has short thoracic postsetal lamellae instead of lamellae that are long and digitiform.

Etymology. This species is named for Mr. Hovie Clifford, Woods Hole Oceanographic Institution (WHOI), who carefully prepared the box cores, pingers, and associated equipment used to collect benthic samples on the SF-DODS surveys.

Distribution. Off northern California in lower continental slope depths, 2600–3136 m.

Figures

FIGURE 1. Leitoscoloplos cliffordi n. sp. Paratype (LACM-AHF Poly 11657): A, anterior end, dorsal view. Paratype (LACM- AHF Poly 11655): B, thoracic setiger, posterior view; C, anterior abdominal setiger, anterior view; D, far posterior abdominal setiger, anterior view; E, notopodial furcate seta.

FIGURE 2. Leitoscoloplos cliffordi n. sp. Holotype (LACM AHF-Poly 11654): A, anterior end, ventral view; B, posterior thoracic and anterior abdominal segments, left lateral view, setigers numbered; C, mid-abdominal segments, left lateral view. B–C: Arrows denote annular rings. Stained with Shirlastain A.