A new species of the Y-larva genus Hansenocaris Itô, 1985 (Crustacea: Thecostraca: Facetotecta) from the Azores, with notes on its morphology and biogeography

Kolbasov, Gregory A.; Savchenko, Alexandra S.; Høeg, Jens T.

doi:10.15298/arthsel.30.3.07

Cited by 5 publications

(16 citation statements)

References 12 publications

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“…Cyprids [based in part on Itô (1985), Kolbasov et al (2007), Høeg et al (2014); also on J. Olesen's unpublished SEM data]: non-feeding, with boat-like, univalved head shield or carapace not covering whole body and free from thorax. Carapace with lattice organs and often with complex pattern of surface sculpturing featuring anterior meshwork and longitudinal ridges.…”

Section: Taxonomymentioning

confidence: 99%

“…The only described genus, Hansenocaris Itô, 1985 (q.v. ), was established with four nominal species, and more have been gradually added since (Itô 1986b(Itô , 1989Belmonte 2005;Kolbasov and Høeg 2003;Kolbasov et al 2007Kolbasov et al , 2021aSwathi and Mohan 2019;Olesen et al 2022). A para-taxonomy exists alongside the formal taxonomy, started already by Hansen (1899) as noted above, and continued by Schram (1970Schram ( , 1972, Itô (1986aItô ( , 1987a, Grygier (1987), and Watanabe et al (2000), whereby distinct "types" of naupliar larvae have been assigned Roman-numeral designations.…”

Section: Introductionmentioning

confidence: 99%

“…For seven species of Hansenocaris, the type series consists solely of cypris y individuals (Itô 1985(Itô , 1986b(Itô , 1989Kolbasov et al 2007Kolbasov et al , 2021b. This has practical value as this stage is certainly homologous between species.…”

Section: Introductionmentioning

confidence: 99%

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Two New Species of Lecithotrophic Nauplius y with Remarkable Labra from Okinawa, Japan, and a Family-Group Name for y-Larvae (Crustacea: Thecostraca: Facetotecta: Hansenocarididae fam. nov.)

Olesen

Grygier

2022

Spec.Div.

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http://zoobank.org/DE06A95A-7DC2-41BA-B94B-2E8DDA5FBE86 Two large (ca. 0.5 mm long), rare, and probably closely related species of Facetotecta (y-larvae), Hansenocaris cristalabri sp. nov. and Hansenocaris aquila sp. nov., are described on the basis of last-stage lecithotrophic nauplii reared from plankton at Sesoko Island, Okinawa, Japan. The two species resemble each other in having a labrum with a row of spines and a long, attenuate trunk region that terminates in a long, heavily spinose dorsocaudal spine. The labrum of H. cristalabri sp. nov. has an enormous, cockscomb-like ventral process that bears a row of distally directed, dagger-like spines along its anterior side, while the spine-bearing keel of the labrum of H. aquila sp. nov. extends posteriorly into a robust, eaglelike beak. The labral "crest" of H. cristalabri sp. nov. has no equivalent in any other described y-larva, nor in any other crustacean nauplius; its possible functions are discussed. Another diagnostic feature of H. cristalabri sp. nov., absent in H. aquila sp. nov., is a pair of shallow, rounded notches bounded by sharp spinules on the far posteriolateral margins of the cephalic shield. Both new species have longitudinal spine rows on the trunk dorsum, two rows in H. cristalabri sp. nov. and four in H. aquila sp. nov., something not previously documented for y-nauplii. The plate arrangement of the cephalic shield in H. cristalabri sp. nov. is described in detail, with an attempt to homologize the pattern with that of other y-nauplii (especially Hansenocaris furcifera Itô, 1989). The body surface of H. cristalabri sp. nov. has fewer setae and pores than any other late-or last-stage facetotectan nauplius described to date, suggesting paedomorphic development. A formal diagnosis is presented for the family-group taxon Hansenocarididae fam. nov.; this name, while already in use, has until now been nomenclaturally unavailable.

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Section: Taxonomymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Two New Species of Lecithotrophic Nauplius y with Remarkable Labra from Okinawa, Japan, and a Family-Group Name for y-Larvae (Crustacea: Thecostraca: Facetotecta: Hansenocarididae fam. nov.)

Olesen

Grygier

2022

Spec.Div.

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“…Although the naupliar and cypridiform stages of the enigmatic y‐larvae of Facetotecta have been found in the marine plankton worldwide, they still represent the last significant group of crustaceans for which the adult forms are still unknown (Glenner et al, 2008 ; Grygier, 1996 ; Høeg et al, 2014 ; Kolbasov et al, 2021a ; Kolbasov & Høeg, 2003 ). Different facetotectan nauplii were first described in detail more than 100 years ago by Hansen ( 1899 ), who originally illustrated five different naupliar types of y‐larvae from West Indian, equatorial Atlantic waters, and from the Bay of Kiel in the Baltic.…”

Section: Introductionmentioning

confidence: 99%

“…Different facetotectan nauplii were first described in detail more than 100 years ago by Hansen ( 1899 ), who originally illustrated five different naupliar types of y‐larvae from West Indian, equatorial Atlantic waters, and from the Bay of Kiel in the Baltic. Subsequently, y‐larvae were reported from almost all oceans in the world (Belmonte, 2005 ; Kolbasov et al, 2021a ; Kolbasov & Høeg, 2003 ; Ponomarenko & Korn, 2006 ). A post‐naupliar instar or “y‐cyprid” (Figure 1 ), resembling other thecostracan cypridiform larvae, was first described by Bresciani ( 1965 ).…”

Section: Introductionmentioning

confidence: 99%

A synthesis of the external morphology of cypridiform larvae of Facetotecta (crustacea: Thecostraca) and the limits of the genus Hansenocaris

Kolbasov

Savchenko

Dreyer

et al. 2022

Ecology and Evolution

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Although the naupliar and cypridiform stages of the enigmatic y‐larvae of Facetotecta have been found in the marine plankton worldwide, they still represent the last significant group of crustaceans for which the adult forms are still unknown. From a number of y‐cyprids representing different taxa from different locations, we employ scanning electron microscopy to describe fine morphological details of all external structures of this unique larval form. We document different segmentation patterns of the abdomen and presence/absence of the labrum and structural differences in the antennules, labrum, paraocular process, thoracopods, and telson lend support for the erection of several new genera as opposed to the single Hansenocaris . The data presented here emphasize the morphological limits of the genus Hansenocaris and the “bauplan” of cyprydiform larvae of Facetotecta. Although the optimum pathway is a joint analysis of both molecular and morphological characters, we use the morphological characters of y‐cyprids to align them cladistically and determine the limits of the genus Hansenocaris s.s. and describe common characters for all y‐cyprids including six pairs of the lattice organs instead five pairs considered as a ground pattern for all Thecostraca. We also determine plesiomorphic and apomorphic characters of all known y‐cyprids and separate them from other thecostracan cypridiform larvae.

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Autofluorescence imaging of exuviae as a tool for studying slide preparations of micro-arthropods, exemplified by a museum collection of the enigmatic crustacean “y-larvae” (Pancrustacea: Facetotecta)

Olesen,

Grygier,

Herranz

2024

Zoomorphology

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In recent years, fluorescence microscopy has revitalized the study of invertebrate comparative morphology. Here we explore the usefulness of combining confocal laser scanning microscopy (CLSM) and cuticular autofluorescence to examine the taxonomically challenging marine planktonic “y-larvae” (Pancrustacea: Facetotecta). To gauge the effectiveness of CLSM with autofluorescence in producing taxonomically useful images, we applied it to seven distinct y-naupliar species or morphospecies that had previously undergone scrutiny by other techniques. The specimens were part of a museum collection of glycerin-jelly slides of exuviae of last-stage y-nauplii, a key instar for studying the taxonomy of y-larvae. For Hansenocaris demodex, the level of detail obtained from a single specimen was comparable to that previously obtained by scanning electron microscopy (SEM). For Hansenocaris aquila, revisiting the original holotype specimen resulted in a dramatic increase in our understanding of the species’ morphology, including taxonomically pivotal information about its spinose labrum and a digitally rotated lateral view. CLSM analyses of the other five specimens, which represented a broad spectrum of y-naupliar morphology, efficiently generated more such information. Novel observations were made concerning putative external rudiments of both the first and second maxillae in late nauplii as well as the extreme dorso-ventral flattening of some naupliar types. CLSM observation of museum slides of naupliar exuviae using cuticular autofluorescence thus shows great promise of becoming an excellent tool for studying the morphology and taxonomy of y-larvae, and we suggest that this technique might also profitably be applied to other forms of larval exuviae.

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A new species of the Y-larva genus Hansenocaris Itô, 1985 (Crustacea: Thecostraca: Facetotecta) from the Azores, with notes on its morphology and biogeography

Cited by 5 publications

References 12 publications

Two New Species of Lecithotrophic Nauplius y with Remarkable Labra from Okinawa, Japan, and a Family-Group Name for y-Larvae (Crustacea: Thecostraca: Facetotecta: Hansenocarididae fam. nov.)

Two New Species of Lecithotrophic Nauplius y with Remarkable Labra from Okinawa, Japan, and a Family-Group Name for y-Larvae (Crustacea: Thecostraca: Facetotecta: Hansenocarididae fam. nov.)

A synthesis of the external morphology of cypridiform larvae of Facetotecta (crustacea: Thecostraca) and the limits of the genus Hansenocaris

Autofluorescence imaging of exuviae as a tool for studying slide preparations of micro-arthropods, exemplified by a museum collection of the enigmatic crustacean “y-larvae” (Pancrustacea: Facetotecta)

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