Aphelochaeta brandtae, Blake, 2018

Blake, James A., 2018, Bitentaculate Cirratulidae (Annelida, Polychaeta) collected chiefly during cruises of the R / V Anton Bruun, USNS Eltanin, USCG Glacier, R / V Hero, RVIB Nathaniel B. Palmer, and R / V Polarstern from the Southern Ocean, Antarctica, and off Western South America, Zootaxa 4537 (1), pp. 1-130 : 18-20

publication ID

https://doi.org/ 10.11646/zootaxa.4537.1.1

publication LSID

lsid:zoobank.org:pub:169CBE5C-3A6E-438B-8A81-0491CBFBAC85

DOI

https://doi.org/10.5281/zenodo.3798616

persistent identifier

https://treatment.plazi.org/id/03A2CB16-FFE4-A259-FF36-FD66FAFBFD40

treatment provided by

Plazi

scientific name

Aphelochaeta brandtae
status

sp. nov.

Aphelochaeta brandtae View in CoL new species

Figures 6–7 View FIGURE 6 View FIGURE 7

Material examined. Weddell Sea, E of Antarctic Peninsula , R / V Polarstern, ANDEEP II (ANT-XIX/4) , Sta. PS 61/133-5, 07 Mar 2002, 65°20.27ʹS, 54°12.54ʹW, MUC, 1166 m, holotype ( SMF 24954); Sta. PS 61/132-6, 07 Mar 2002, 65°17.77ʹS, 54°0.00ʹW, box corer, 2086 m, 1 paratype ( MCZ 1439888 View Materials ).— Weddell Sea, off Coats Land , USCG GoogleMaps Glacier, Sta. 69-20, 12 Mar 1969, 73.823°S, 31.682°W, 2288 m (1, USNM 1490706 View Materials ).— Drake Passage, North of South Shetland Islands, R / V GoogleMaps Polarstern, ANDEEP I (ANT-XIX/3), Sta. PS61/43-2, 29 Jan 2002, 60°26.95ʹS, 56°4.96ʹW, box corer, 3957 m, 3 paratypes ( SMF 249556 View Materials ).— Scotia Sea , R / V GoogleMaps Polarstern, ANDEEP I (ANT-XIX/3), Sta. PS61/46-3, 01 Jan 2002, 60°37.92ʹS, 53°57.17ʹW, box corer, 2888 m, 8 paratypes ( SMF 24956); Sta. PS61/46-5, 01 Jan 2002, 60°38.13ʹS, 53°57.68ʹW, box corer, 2894 m, 2 paratypes ( SMF 24957) GoogleMaps .

Description. A small species, all specimens incomplete; holotype an ovigerous female, mostly complete, 6.4 mm long, 0.4 mm wide across anterior segments, with 39 setigers; paratype from Sta. 46-3, 5.9 mm long, 0.44 mm wide across expanded anterior setigers, with 31 segments. Anterior 7–10 segments narrow, about eight times wider than long ( Fig. 6 View FIGURE 6 A–B), then narrowing to 12–20 middle rounded segments about as wide as long, not moniliform ( Fig. 7B View FIGURE 7 ); last 7–10 segments narrow, elongate. Anterior expanded segments with prominent parapodial shoulders and low rounded dorsum slightly elevated over parapodia ( Fig. 6 View FIGURE 6 A–B), without longitudinal groove. Venter weakly rounded, typically without ventral groove, specimen from Glacier Sta. 69-20 (USNM 46797) with narrow ventral groove from middle segments to end of fragment; each anterior segment with broad band of glandular tissue across venter, that stains with MG ( Fig. 7 View FIGURE 7 A–B). Holotype with large oblong eggs protruding from body in pairs ( Fig. 7 View FIGURE 7 D–E), four per segment; individual eggs approximately 280 x 150 µm. Color in alcohol light tan; no accessory pigment.

Prostomium triangular, narrowing to pointed tip on anterior margin ( Fig. 6 View FIGURE 6 A–B); eyespots absent; nuchal organs narrow slits located laterally just anterior to peristomium ( Fig. 6B View FIGURE 6 ). Peristomium with two annular rings, second twice as long as first, best seen laterally ( Fig. 6 View FIGURE 6 A–B); second ring sometimes subdivided into a third ring; annular grooves lateral, not extending over dorsum; dorsal surface with prominent dorsal crest extending from end of first annular ring to anterior margin of setiger 1 ( Fig. 6 View FIGURE 6 A–B). Dorsal tentacles arising at posterior margin of peristomium lateral to dorsal ridge ( Fig. 6 View FIGURE 6 A–B). First pair of branchiae posterior and lateral to dorsal tentacles on posterior margin of peristomium; second pair of branchiae arising from posterior margin of setiger 1, posterior to notosetae ( Fig. 6B View FIGURE 6 ).

Anterior parapodial shoulders elevated over dorsum, prominent on setigers 7–10, depending on size of specimen ( Fig. 6 View FIGURE 6 A–B); holotype with eight anterior setigers ( Fig. 6B View FIGURE 6 ); paratype with 10 ( Fig. 6A View FIGURE 6 ); anterior setae arising from low podial lobes; noto- and neurosetae arising close together along entire body. Setae all capillaries, some long but not natatory, with about 11–13 per notopodia and 8–10 in neuropodia in expanded anterior setigers, reduced to 4–5 in middle and posterior segments. Capillaries all thin, appearing smooth in light microscopy.

Methyl Green stain. Prominent and distinctive MG pattern present; some specimens staining strongly, others lightly. Prostomium and peristomium with distinct pattern dorsally, separated by unstained area ( Fig. 7A, C View FIGURE 7 ); dorsally stained area terminating abruptly at posterior margin of peristomium ( Fig. 7C View FIGURE 7 ); peristomial stain continuing around to ventral side, but not as prominent and limited to posterior half of peristomium. Holotype with strong prostomial stains dorsally and ventrally, but with peristomial stain lighter, reduced to a speckled pattern. Stain concentrated in dorsal segmental grooves on a few anterior segments. Ventrally, broad glandular bands of anterior segments staining intensely producing broad dark blue stripes across venter of anterior segments ( Fig. 7 View FIGURE 7 A–B), some specimens with ventral stripes on most anterior segments, others limited to 2–4 segments, but these very intense and distinctive; ventral stripes extending laterally up and onto neuropodia, but not crossing dorsum.

Etymology. This species is named for Prof. Dr. Angelika Brandt, prominent pericarid specialist, deep-sea ecologist, and friend. Dr. Brandt was the expedition leader for the ANDEEP surveys of deep-sea habitats in Antarctica. She is currently Head of the Department of Marine Zoology at the Senckenberg Research Institute and Natural History Museum Frankfurt, Germany.

Remarks. Aphelochaeta brandtae n. sp. is a relatively small deep-sea cirratulid that is readily distinguished from its congeners in having a smooth pre-setiger region, short expanded anterior thoracic region, and a distinctive MG staining pattern. Anterior setigers transition abruptly to more or less rounded or oval abdominal segments with reduced parapodia; these segments are not moniliform.

The large, paired oblong eggs that protrude from the body wall of this species ( Fig. 7 View FIGURE 7 D–E) are unusual and suggest a modified type of reproduction with direct development and possible brood protection.

The MG stain is distinctive with a defined pre-setiger staining pattern on prostomium and peristomium and with a clear ocular area between them, similar to that of A. spectabilis n. sp. However, the very intensely stained broad transverse MG stripes on the venter are unique among Antarctic bitentaculate cirratulids. In addition, A. spectabilis n. sp. does not have rounded abdominal segments.

Habitat. Sediments from the Drake Passage and Scotia Sea samples were typical deep-sea silt-clay with some cobble; samples from the Weddell Sea were greenish grey, silt-clay with some sand and pebbles ( Diaz 2004; Howe et al. 2004).

Distribution. Antarctica: Drake Passage, Scotia Sea, Weddell Sea; slope and abyssal depths, 1166–3957 m.

R

Departamento de Geologia, Universidad de Chile

V

Royal British Columbia Museum - Herbarium

SMF

Forschungsinstitut und Natur-Museum Senckenberg

USCG

Universidad de San Carlos de Guatemala

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