Orbiniella landrumae, 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 : 115

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.4901831

persistent identifier

https://treatment.plazi.org/id/8F2387DD-0667-097F-FF31-FE84FC9FF9C6

treatment provided by

GgServerImporter

scientific name

Orbiniella landrumae
status

sp. nov.

Orbiniella landrumae View in CoL new species

Figure 56 View FIGURE 56

Material examined. Juan Fernandez Islands, Anton Bruun Cruise 12, Sta. 65-240, 12 Dec 1965, 33.622°S, 78.839°W, 26–29 m, holotype and 3 paratypes ( USNM 1013912–3 View Materials ) GoogleMaps ; Sta. 65-243, 12 Dec 1965, 33.62°S, 78.847°W, 0–10 m, 3 paratypes (USNM 1013914).

Description. A small species, holotype complete, 2.23 mm long, 0.29 mm wide for 23 setigers; one incomplete paratype 2.86 mm long, 0.2 mm wide for 20 setigers; other paratypes smaller. Color in alcohol: opaque white.

Prostomium smoothly rounded on anterior margin; with two crescent-shaped red eyespots ( Fig. 56 View FIGURE 56 A). Peristomium with two indistinct achaetous rings, but distinctly separated from setiger 1. All segments similar, with no demarcation between thorax and abdomen. Notopodia with short digitiform postsetal lobes throughout; neuropodia with short postsetal lobes in anterior setigers; absent in posterior setigers.

Notosetae including 3–4 crenulated capillaries ( Fig. 56 View FIGURE 56 B), a single flail seta ( Fig. 56 View FIGURE 56 C) and a single furcate seta ( Fig. 56 View FIGURE 56 D); flail seta with tapering tip and reduced numbers of crenulations; furcate seta with unequal tynes, shorter blunt-tipped, longer thinner and pointed; tynes connected by thin webbing with fine needles. Neurosetae including crenulated capillaries and 1–2 modified crenulated spines in anterior setigers and 0–1 crenulated capillaries and 3– 4 spines in posterior setigers; spines unique, recurved, with broad crenulated blade terminating in pointed tip ( Fig. 56 View FIGURE 56 E).

Branchiae absent. Some specimens with large yolky eggs up to 190 µm across widest dimension. Eggs with two nucleoli observed in germinal vesicle ( Fig. 56 View FIGURE 56 F).

Pygidium with anus directed posteriorly, surrounded by four cirri; dorsal pair shorter, triangular in shape, ventral pair longer and cirriform ( Fig. 56 View FIGURE 56 G).

Etymology. This species is named for Ms. Betty J. Landrum of the former Smithsonian Oceanographic Sorting Center. Ms. Landrum provided support and encouragement during the course of this study and of another project on Antarctic polychaetes.

Remarks. Orbiniella landrumae n. sp. is only provisionally referred to Orbiniella because it differs from related species in having notopodial furcate setae, flail setae, and an unusual type of crenulated neuropodial spine. However, the species does not have distinct body regions, parapodia are reduced, branchiae are absent, two peristomial rings are present, and the posterior parapodia are not elevated as is typical for species of Orbiniella . Further, large ova of 190 µm present in the holotype indicate sexual maturity. Further study is needed to more adequately address the generic placement of this species.

Distribution. Juan Fernandez Islands, intertidal to 29 m.

USNM

Smithsonian Institution, National Museum of Natural History

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Family

Orbiniidae

Genus

Orbiniella

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