Orbiniella grasslei, 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 : 41-44

publication ID

https://doi.org/ 10.11646/zootaxa.4730.1.1

publication LSID

lsid:zoobank.org:pub:7F4CD129-9FF9-4593-A8A4-DB999B3E402F

persistent identifier

https://treatment.plazi.org/id/C1344615-DC39-4782-89FB-F7DBBAB3ECA1

taxon LSID

lsid:zoobank.org:act:C1344615-DC39-4782-89FB-F7DBBAB3ECA1

treatment provided by

Plazi

scientific name

Orbiniella grasslei
status

sp. nov.

Orbiniella grasslei View in CoL new species

Figure 21 View FIGURE 21

urn:lsid:zoobank.org:act:C1344615-DC39-4782-89FB-F7DBBAB3ECA1

Material examined. East Pacific Rise, hydrothermal vent area at 21°N: HOV Alvin Dive 1221-15, 20°50′N;

109°06′W, 4 May 1982, 1618 m, washings of Riftia pachyptila tubes and Calyptogena magnifica shells, holotype ( MCZ 153574 ) and 3 paratypes ( MCZ 153575 About MCZ ) ; HOV Alvin Dive 1223-17, 20°50′N; 109°06′W, 7 May 1982, 2616 GoogleMaps

m, rubble, 4 paratypes ( MCZ 153576 About MCZ ); HOV Alvin Dive 1223-11, 7 20°50′N; 109°06′W, 7 May 1982, 2616 m, fine fraction from washings, 3 specimens ( MCZ 153577 About MCZ ) GoogleMaps .

Description. Holotype largest specimen, complete, 5.44 mm long and 0.22 mm wide for 26 setigers. Body not divided into distinct thoracic and abdominal regions; body segments all similar. Parapodia reduced, lamellae lacking.

Pre-setiger region thick, with prostomium and peristomium lacking obvious separation dorsally and laterally ( Fig. 21A View FIGURE 21 ). Prostomium broadly rounded anteriorly; eyespots absent, nuchal organs not visible. Peristomium entirely merged with prostomium dorsally; ventrally with a large ventral lip below mouth; two partial annular rings weakly developed, only apparent ventrally ( Fig. 21A View FIGURE 21 ).

Setiger 1 and following segments separated from one another by swollen intersegmental annular rings produc- ing biannulate segments ( Fig. 21A View FIGURE 21 ). Notopodia bearing 2–3 camerated capillaries and three serrated spines from setiger 1; spines reduced to two by setiger 5, continuing to posterior setigers where only a single spine and two capillaries persist ( Fig. 21 View FIGURE 21 B–C). Neuropodia bearing two spines and three capillaries from setiger 1, increasing to three spines and five capillaries by setiger 5, reduced to two spines and 0–2 capillaries in posterior setigers ( Fig. 21 View FIGURE 21 B–C). Spines with distinct serrations along shaft ( Fig. 21C View FIGURE 21 ).

Pygidial segment simple, lacking cirri.

Methyl Green stain. No pattern.

Remarks. Orbiniella grasslei n. sp. is most similar to O. hobsonae Blake & Hilbig, 1990 from hydrothermal vents on the Juan de Fuca Ridge. Both species have long, thin bodies and acicular spines with a row of barbs or serrations along the shaft. Orbiniella grasslei n. sp. differs from O. hobsonae in having a peristomium on which the annular rings are indistinct instead of being present as two distinct rings; in addition, nuchal organs are not visible instead of being prominent laterally on the prostomium. The most conspicuous difference between O. grasslei n. sp. and O. hobson ae, however, is the segmentation. In O. grasslei n. sp., the intersegmental groove is expanded into a large swelling that provides a prominent biannulate appearance to segments along the body. In contrast, the segments of O. hobsonae are entirely uniannulate. There are additional differences in the fine details of the structure of the spines and capillary setae. Another species of Orbiniella , O. aciculata Blake, 1985 , from the vicinity of the Galápagos Rift hydrothermal vents has spines that are smooth instead of serrated, and the body is short and compact instead of long and thin.

Etymology. This species is named for the late Dr. J. Frederick Grassle, prominent deep-sea benthic ecologist of the Woods Hole Oceanographic Institution and the Rutgers University Institute of Marine and Coastal Sciences. As part of his numerous expeditions to deep-sea locations, Dr. Grassle provided this author and other investigators with numerous polychaetes from vents and other habitats that have resulted in a rich harvest of new species.

Distribution. Hydrothermal vents on the East Pacific Rise at 21°N, 1618–2616 m.

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Family

Orbiniidae

Genus

Orbiniella

GBIF Dataset (for parent article) Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF