Leitoscoloplos chilensis ( Hartmann-Schröder, 1965 ), Hartmann-Schroder, 1965

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 : 21-22

Leitoscoloplos chilensis ( Hartmann-Schröder, 1965)

Figure 7

Scoloplos kerguelensis: Monro 1936: 160 (in part). Not McIntosh 1885. Fide Mackie 1987. Haploscoloplos kerguelensis chilensis Hartmann-Schröder, 1965: 194 –195, fig. 178; Carrasco 1977: 68 –69, figs. 1–4; Rozbaczylo 1985: 129.

Leitoscoloplos chilensis: Mackie 1987: 11 –12, fig. 11.

Material examined. Chile, Punta Iloca , 34°56′S, 72°14′W, 5 Mar 1960, 50 m, fine sand with detritus, holotype of Haploscoloplos kerguelensis chilensis (ZMH-P-14863); Seno Reloneavi, the Bay off Puerto Montt, N of the light buoy NE of Isla Tengo, LUCE Sta. M-4A , 13–16 m (2, SMNH 154442); Canal Chacao, Bahía de Ancud, Lechagua , LUCE Sta. M-11A, intertidal (1, SMNH 154437 ) ; Golfo de Ancud, SW of Isla Tabon, LUCE Sta. M- 44A, ca . 200 m (3, SEM, JAB); Golfo Ancud, northern part, Canal San Antonio , LUCE Sta. M- 108, 60 m, (1, SMNH 154441 ); off Valparaiso, Eltanin Sta. 21-194, 137 – 141 m (4, USNM 69383 ).— Straits of Magellan , east of Isla Dawson, R/V Vema Sta. V-17-23, 273 – 280 m (2, LACM-AHF Poly 5003).

Comparative material examined. California, numerous specimens of Leitoscoloplos pugettensis from California ( Bodega Harbor , Tomales Bay and Gulf of the Farallones ) and Canada ( Prince Rupert , British Columbia), intertidal to 50 m (JAB).

Description. One complete specimen 24 mm long, 1.2 mm wide for 150 setigerous segments; other specimens up to 40 mm long and 2.0 mm wide for about 90 setigers; with 13–16 thoracic setigers. Color in alcohol: light tan.

Prostomium conical, tapering to narrow anterior tip; without eyespots ( Fig. 7 A). Peristomium wider than long, with pair of nuchal organs on anterior lateral margin. Two specimens from Strait of Magellan with multi-lobed proboscis everted.

Thoracic notopodia with narrow elongate triangular-shaped postsetal lamella; thoracic neuropodia with elongate postsetal lamellae arising from prominent cushion or mound ( Fig. 7 B); abdominal segments with leaflike, subtriangular notopodial postsetal lamellae ( Fig. 7 C–D); neuropodia simple, bifid on tip, but lacking ventral cirrus ( Fig. 7 D), with prominent inflated subpodial flange present ventral to neuropodia throughout abdominal region ( Fig. 7 C–D); subpodial lobes absent.

Thoracic noto- and neurosetae and abdominal neurosetae all crenulated capillaries, with crenulations consisting of numerous transverse rows of barbs ( Fig. 7 H); abdominal notosetae including capillaries and furcate setae; furcate setae with two blunt-tipped unequal tynes connected by delicate rows of fine needles within a membrane; barbs not apparent on shaft ( Fig. 7 F); with SEM, tips of tynes with opening ( Fig. 7 G). Abdominal neurosetae smooth, not camerated, including separate dorsal fascicle of long, thin capillaries and a more ventral fascicle of 3–4 fine flail setae, not evident in middle and posterior abdominal neuropodia; flail setae curved, capillary tipped, difficult to see with light microscopy ( Fig. 7 C-inset).

Branchiae first present from setiger 13–16; anterior branchiae short, narrow, tapering to pointed tip; increasing in size posteriorly, with abdominal branchiae about twice as long as notopodial lobes; each branchia with distinct subapical flaglike lateral swelling ( Fig. 7 C–D).

Pygidium with four lobes surrounding terminal anus; two long anal cirri present ( Fig. 7 E).

Remarks. Haploscoloplos kerguelensis chilensis was raised to full species status by Mackie (1987). Leitoscoloplos chilensis appears to be most similar to L. pugettensis in numbers of thoracic setigers, general appearance of the parapodia, and form of the branchiae. The species is characterized by having branchiae first present from one of the last thoracic setigers. Each branchia has a subapical flaglike swelling directed laterally. The abdominal neuropodial lobes are bifid and a long, conspicuous subpodial flange is present.

Initially, I considered that the Chilean specimens might be conspecific with L. pugettensis . However, careful study of the parapodia suggested otherwise. Leitoscoloplos chilensis has 13–16 thoracic setigers and branchiae from about setigers 12–16; L. pugettensis has 14–20 setigers with branchiae from setigers 13–18. The greater number of thoracic setigers and greater range of branchial initiation in L. pugettensis may, however, be due to much larger specimens being recorded ( Hartman 1957; Pettibone 1957; Blake 2000). The branchiae of both species have distal expansions that in L. chilensis are directed laterally and fully swollen in both directions in L. pugettensis . More important differences are with the thoracic parapodia where the neuropodial postsetal lamellae of L. chilensis are longer, more triangular in shape; these are shorter and more papillate than L. pugettensis . The short interramal papilla in anterior abdominal segments of L. chilensis is difficult to observe and has not been reported for L.

pugettensis . The discovery of flail setae in the anterior abdominal neuropodia of L. chilensis prompted an examination of L. pugettensis and these minute setae were also present in specimens examined from British Columbia (Blake unpublished) and Costa Rica ( Dean & Blake 2015: Fig. 6 B). To date these are the only known examples of flail setae in the genus Leitoscoloplos .

The very close similarity of L. pugettensis and L. chilensis suggest a cline between a single wide ranging Eastern Pacific species. The main differences are with the branchial morphology and details of the thoracic neuropodial lamellae. Differences in numbers of thoracic setigers and initiation of the branchiae are likely size related with larger specimens only available for L. pugettensis . The current distribution of L. pugettensis is from Alaska to Costa Rica ( Blake 1996; Dean & Blake 2015); L. chilensis has not been recorded north of Chile.

Distribution. Western Chile, intertidal to 50 m; Straits of Magellan, 273– 280 m.

Figures

FIGURE 6. Leitoscoloplos abranchiatus (Hartman, 1967). Holotype (USNM 55531). A, anterior end, dorsal view; B, abdominal parapodium, anterior view; C, furcate seta. — Leitoscoloplos simplex n. sp. Holotype (USNM 1407119). D, anterior end, dorsal view; E, anterior abdominal parapodium, posterior view.

FIGURE 7. Leitoscoloplos chilensis (Hartmann-Schröder, 1965). Chile, Seno Reloneavi, off Puerto Montt, Lund University Chile Expedition, Sta. M- 4 A (SMNH 154442). A, anterior end, dorsal view; B, thoracic parapodium, posterior view; C, anterior abdominal parapodium, anterior view, arrow indicates interramal papilla, inset of flail setae (not to scale); D, middle abdominal parapodium, anterior view; E, posterior end, dorsal view; F, furcate seta; G, SEM of furcate seta with opening on tip of long tyne; H, SEM detail of barbs on thoracic capillaries.