Scoloplos suroestense, Blake, James A., 2017

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 : 47

publication ID

https://doi.org/ 10.5281/zenodo.245827

publication LSID

lsid:zoobank.org:pub:9345C596-8656-4B5C-AD8C-2FACF4E9240C

DOI

https://doi.org/10.5281/zenodo.4901771

persistent identifier

https://treatment.plazi.org/id/8F2387DD-063B-0923-FF31-FDCFFCE5F853

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scientific name

Scoloplos suroestense
status

sp. nov.

Scoloplos suroestense View in CoL new species

Figures 23 View FIGURE 23 G–H, 24

Material examined. Juan Fernandez Islands , Chile Bay behind Punta Suroestense , Anton Bruun Cruise 12, Sta. 134, 13 Dec 1965, 33°34′S, 78°55′W, shallow subtidal (<5m), holotype and 3 paratypes ( USNM 1013917–8 View Materials ). GoogleMaps

Description. Holotype complete, 12 mm long and 1.2 mm wide for approximately 100 segments; paratypes smaller, up to 75 segments. First four thoracic segments distinctly inflated, due to inverted proboscis visible dorsally through body wall ( Figs. 23 View FIGURE 23 G, 24A–B); following thoracic segments distinctly depressed ( Figs. 23 View FIGURE 23 A, 24B– C); abdominal segments rounded in cross section ( Fig. 24 View FIGURE 24 D). Thorax with 10–15 setigers, depending upon size of specimens; smallest specimens with fewest thoracic segments, larger specimens with most thoracic segments; last 1–2 thoracic segments appearing transitional with abdominal region in having fewer, more tightly grouped setae. Color in alcohol: light tan.

Prostomium triangular, pointed anteriorly ( Figs. 23 View FIGURE 23 G, 24A–B); no eyespots; with two ciliated dorsolateral nuchal organs on posterior border with peristomium of holotype ( Fig. 24 View FIGURE 24 A); with SEM, nuchal organ of paratype a slit ( Fig. 23 View FIGURE 23 A). Peristomium with a single achaetous ring completely fused to setiger 1.

Thoracic parapodia with digitiform postsetal lobes from setiger 1 ( Fig. 24 View FIGURE 24 A–B); neuropodial lobes slightly shorter than notopodial lobes. Anterior abdominal postsetal lobes similar to those of thoracic region, with neuropodial lobes becoming reduced to short papillae in middle body segments; notopodial lobes remaining long, but shorter than branchiae ( Fig. 24 View FIGURE 24 D). No interramal or subpodial lobes present.

Notosetae all crenulated capillaries throughout; furcate setae entirely absent. Thoracic neurosetae including 8– 9 uncini located anterior to 12–14 crenulated capillaries ( Figs. 23 View FIGURE 23 H, 24C); uncini slender, no broader than capillaries, with blunted curved tips partially covered by hyaline hood ( Fig. 24 View FIGURE 24 E–F), in SEM hood appearing as a sheath extending from tip of shaft posteriorly ( Fig. 23 View FIGURE 23 H); shafts with ribs that in light microscope and SEM consist of transverse rows of barbs ( Figs. 23 View FIGURE 23 H, 24E–F), capillaries with transverse rows of barbs ( Figs. 23 View FIGURE 23 H, 24G). Abdominal neurosetae including 2–3 straight pointed uncini ( Fig. 24 View FIGURE 24 H) and 3–4 capillaries.

Branchiae from setiger 12–17 or first 1–2 abdominal segments ( Fig. 24 View FIGURE 24 B).

Pygidium with terminal anus, encompassed by broad, thickened lobe, without anal cirri.

Remarks. Scoloplos suroestense n. sp. is unusual among species of Scoloplos in having branchiae first present from anterior abdominal setigers. In this regard, the species is closely related to S. normalis ( Day, 1977) and S. difficilis Day, 1977 , both from Australia ( Hartman 1957; Day 1977; Mackie 1987). Scoloplos normalis , originally described in the genus Leitoscoloplos by Day (1977), was transferred to Scoloplos by Mackie (1987) after he discovered that the paratypes had a few short, robust and weakly serrated uncini with a close adhering hood among neuropodial capillaries of the first three thoracic setigers; one small specimen had uncini distributed over a greater range of setigers. Scoloplos suroestense n. sp., in contrast, has 8–9 uncini and 12–14 capillaries in all thoracic neuropodia. Further the uncini of S. suroestense n. sp. have rows of barbs all along the shaft and bear a thin hyaline sheath at the tip. The nature of the thoracic neuropodial uncini on S. suroestense n. sp. also differs from the smooth shafted uncini reported by Day (1977) for S. difficilis .

Etymology. The epithet is taken from Punta Suroestense , near the type locality in the Juan Fernandez Islands.

Distribution. Juan Fernandez Islands, shallow subtidal.

USNM

Smithsonian Institution, National Museum of Natural History

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Family

Orbiniidae

Genus

Scoloplos

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