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| Grimpoteuthis imperator Ziegler & Sagorny, 2021 |
Abstract
Background:
In zoology, species descriptions conventionally rely on invasive morphological techniques, frequently leading to damage of the specimens and thus only a partial understanding of their structural complexity. More recently, non-destructive imaging techniques have successfully been used to describe smaller fauna, but this approach has so far not been applied to identify or describe larger animal species. Here, we present a combination of entirely non-invasive as well as minimally invasive methods that permit taxonomic descriptions of large zoological specimens in a more comprehensive manner.
Results:
Using the single available representative of an allegedly novel species of deep-sea cephalopod (Mollusca: Cephalopoda), digital photography, standardized external measurements, high-field magnetic resonance imaging, micro-computed tomography, and DNA barcoding were combined to gather all morphological and molecular characters relevant for a full species description. The results show that this specimen belongs to the cirrate octopod (Octopoda: Cirrata) genus Grimpoteuthis Robson, 1932. Based on the number of suckers, position of web nodules, cirrus length, presence of a radula, and various shell characters, the specimen is designated as the holotype of a new species of dumbo octopus, Grimpoteuthis imperator sp. nov. The digital nature of the acquired data permits a seamless online deposition of raw as well as derived morphological and molecular datasets in publicly accessible repositories.
Conclusions:
Using high-resolution, non-invasive imaging systems intended for the analysis of larger biological objects, all external as well as internal morphological character states relevant for the identification of a new megafaunal species were obtained. Potentially harmful effects on this unique deep-sea cephalopod specimen were avoided by scanning the fixed animal without admixture of a contrast agent. Additional support for the taxonomic placement of the new dumbo octopus species was obtained through DNA barcoding, further underlining the importance of combining morphological and molecular datasets for a holistic description of zoological specimens.
Keywords: Magnetic resonance imaging, Micro-computed tomography, Three-dimensional, Modelling, Taxonomy, Cephalopod, Cirrate, Dumbo
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| Grimpoteuthis imperator sp. nov. ZMB MOLL 240160. a–c Habitus before fixation showing dorsal, ventral, and oral views, anterior facing up. d, e Specimen prior to MRI following several months in 10% formalin solution showing dorsal and ventral views, anterior facing up. Stippled frame denotes the MRI region of interest. f Virtual section through the 3D MRI dataset, anterior facing right. The asterisk denotes a susceptibility artefact in the buccal mass area caused by ingested sediment. g Virtual section through the central long axis of the funnel. h Section of an arm showing the suckers and cirri, right lateral view. i Volume rendering of the viscera, ventral view, anterior facing up. j Close-up of the left gill showing eight broad lamellae. k Volume rendering of the viscera, oblique posterior view |
Family Grimpoteuthidae O’Shea, 1999
Genus Grimpoteuthis Robson, 1932
Type species: Cirroteuthis umbellata Fischer, 1883: 404.
By original designation, Robson 1932: 137.
Grimpoteuthis imperator sp. nov.
Diagnosis: Medium-sized species with moderately long, lateral fins. Cirri short and suckers moderate. Gills compact with eight broad lamellae. Radula present, teeth homodont. Paired anterior and unpaired posterior salivary glands present. Shell U-shaped, smooth with lateral wings parallel, broadly tapering towards distal ends.
Distribution: So far known only from the type locality in the northern part of the Emperor Seamounts, an undersea mountain chain in the northwestern part of the North Pacific.
Etymology: Latin, imperator, noun in apposition. Named after the Emperor Seamounts to which the type locality belongs.
Proposed vernacular names are Emperor Dumbo (English), Dumbo impérial (French), 天皇ダンボ (Japanese), and Kaiserdumbo (German).
Conclusions:
By extending the morphomics concept to the description of a new species of megafauna, we here show that a minimally invasive approach based on the application of complementary non-invasive 3D imaging techniques supplemented with molecular sequence data can help to advance metazoan taxonomy, in particular, in cases where valuable, larger zoological specimens require a more detailed, holistic analysis.
Alexander Ziegler and Christina Sagorny. 2021. Holistic Description of New Deep Sea Megafauna (Cephalopoda: Cirrata) using A Minimally Invasive Approach. BMC Biology. 19: 81. DOI: 10.1186/s12915-021-01000-9
Alan J. Jamieson and Michael Vecchione. 2020. First in situ observation of Cephalopoda at hadal depths (Octopoda: Opisthoteuthidae: Grimpoteuthis sp.). Marine Biology. 167, 82. DOI 10.1007/s00227-020-03701-1 Open Access
Footage captured of cephalopod at deepest ocean level ever observed
