Early Devonian calymenid larvae (Trilobita) from the Bissounel Formation (Montagne Noire, France)

2007 ◽  
Vol 178 (3) ◽  
pp. 197-200 ◽  
Author(s):  
Rudy Lerosey-Aubril
Keyword(s):  
Larval Stage ◽  
Morphological Characteristics ◽  
Developmental Strategy ◽  
Two Stage ◽  
Early Devonian ◽  
Montagne Noire ◽  
Middle Member ◽  
Planktonic Larval Stage ◽  
Late Emsian ◽  
Comparable Size

AbstractThe late Emsian middle Member of the Bissounel Formation (Montagne Noire, France) has yielded a highly diverse silicified trilobite fauna. Among the thousands of disarticulated sclerites discovered, two protaspid specimens were found that display morphological characteristics of planktonic larvae of calymenid trilobites. The presence of calymenid protaspides within a non-calymenid trilobite fauna is noted. The two specimens are very similar to the first planktonic larval stage of the Ordovician Flexicalymene senaria (Conrad, 1841), and are of comparable size. This indicates that, as in F. senaria, a second planktonic larval stage might have occurred in the ontogeny of this undetermined calymenid. Thus, some post-Ordovician calymenids might have retained the ancestral developmental strategy with a two-stage planktonic period. The discovery of these two protaspides constitutes the first evidence of a calymenid trilobite in the Devonian of the Montagne Noire.

Phoronida

2017 ◽  
Author(s):  
Judith Fuchs
Keyword(s):  
Life Cycle ◽  
Small Group ◽  
Larval Stage ◽  
Intertidal Zone ◽  
Marine Invertebrates ◽  
Tree Of Life ◽  
General Morphology ◽  
Family Level ◽  
Planktonic Larval Stage

This chapter describes the taxonomy of Phoronida, a small group of exclusively marine invertebrates found in most of the world's oceans from the intertidal zone to about 400 metres depth. Phoronids are meroplanktonic with a planktonic larval stage usually less than 2 mm in length and a benthic adult whose length ranges from a few cm up to 50 cm. The chapter covers their life cycle, ecology, and general morphology. It includes a section that indicates the systematic placement of the taxon described within the tree of life, and lists the key marine representative illustrated in the chapter (usually to genus or family level). This section also provides information on the taxonomic authorities responsible for the classification adopted, recent changes which might have occurred, and lists relevant taxonomic sources.

New Early Devonian pteraspidids (Agnatha, Heterostraci) from Death Valley National Monument, southeastern California

1996 ◽  
Vol 70 (1) ◽  
pp. 152-161 ◽  
Author(s):  
David K. Elliott ◽  
Robert R. Ilyes
Keyword(s):  
Estuarine Environment ◽  
Death Valley ◽  
Early Devonian ◽  
National Monument ◽  
Bearing Unit ◽  
Late Emsian

Two species and genera of pteraspidids (Agnatha, Heterostraci), Blieckaspis priscillae n. gen., and Panamintaspis snowi n. gen. and n. sp., together with two undetermined species, are described from the lower part of the Lippincott Member of the Lost Burro Formation, southeastern California. The sharing of similar faunal elements with the Early Devonian assemblages of the Sevy Dolomite and Water Canyon Formation of Utah and Nevada, respectively, together with stratigraphic constraints on the age of the Death Valley fauna, suggest that these assemblages are age equivalent and have a late Emsian (inversus–serotinus Zones) age. The vertebrate-bearing unit of the Lippincott Member is interpreted as a channel-fill deposit laid down in an estuarine environment with low or fluctuating salinity.

Skeletal characters for identification of juvenile Ophiactis resiliens and Amphiura constricta (Echinodermata): cryptic ophiuroids in coralline turf habitat

2006 ◽  
Vol 86 (5) ◽  
pp. 1199-1207 ◽  
Author(s):  
I. Falkner ◽  
M. Byrne
Keyword(s):  
Larval Stage ◽  
Early Stage ◽  
Skeletal Development ◽  
Algal Turf ◽  
Disc Diameter ◽  
Planktonic Larval Stage

Skeletal development of Ophiactis resiliens and Amphiura constricta was examined to determine characters that could be used to identify the juveniles of these species, which co-occur in algal turf habitat. Juvenile O. resiliens recruit to turf after a planktonic larval stage while A. constricta recruit through release from brooding adults. Skeletal development in O. resiliens and A. constricta is typical of most ophiuroids with diagnostic adult characters taking some time to appear. The main characters that can be used to distinguish the two species from an early stage are the number and arrangement of the oral papillae and the presence of disc spines. In O. resiliens diagnostic adult skeletal characters developed at 1.5 mm disc diameter. In A. constricta most identifying adult characters were evident at 700 μm disc diameter. Identification of juvenile O. resiliens is assisted by the presence of disc spines and thorny arm spines, features that disappear as the juveniles grow. Juvenile A. constricta did not develop disc spines or thorns on the arm spines.

Description of the first zoeal stage of Synalpheus apioceros Coutière, 1909 (Caridea: Alpheidae), including a comparative analysis with larval morphology from the genus Synalpheus Spence Bate, 1888

Zootaxa ◽  
2020 ◽  
Vol 4838 (1) ◽  
pp. 71-82
Author(s):  
RAFAEL C. SANTOS ◽  
RÉGIS A. PESCINELLI ◽  
ROGERIO C. COSTA
Keyword(s):  
Comparative Analysis ◽  
Larval Development ◽  
Larval Stage ◽  
Morphological Characteristics ◽  
Plumose Seta ◽  
Zoeal Stage ◽  
Larval Morphology ◽  
Morphological Similarity ◽  
Similar Morphology ◽  
Larval Stages

Herein, the Zoea I of Synalpheus apioceros is described, followed by a comparative analysis of the first larval stage from Synalpheus. Larvae were obtained from two ovigerous females sampled in Ubatuba, São Paulo. The morphology of the Zoea I of S. apioceros was compared to five other Synalpheus species whose structures were previously described: S. biunguiculatus, S. minus, S. neomeris, S. pectiniger, and S. tumidomanus. A set of unique morphological characteristics was found for S. apioceros: exopod of antennule with 4 aesthetascs and 1 plumose seta; coxal endite of maxillule with 2 simple setae plus 2 plumose setae; basial endite of maxillule with 2 simple setae plus 2 short spines; endopod of maxillule with 1 plumose seta plus 2 simple setae; basial endite of maxilla bilobed with 2 (1 plumose and 1 simple) + 2 (1 plumose and 1 simple) setae; coxal endite of maxilla bilobed with 2 + 1 plumose setae; endopod of maxilla with 3 (1 plumose and 2 simple) terminal setae + 2 simple setae; endopod of first maxilliped unsegmented with 3 terminal simple setae; basis of first maxilliped with 5 spines; endopod of second maxilliped 5-segmented with 0, 0, 0, 1 plumodenticulate, 4 (1 serrate + 3 simple) setae; endopod of third maxilliped 5-segmented with 0, 0, 0, 1 simple, 3 simple setae; pereiopods 1st to 3rd birramous and 4th and 5th uniramous. S. apioceros shows higher morphological similarity with S. minus, followed by S. tumidomanus, S. neomeris and S. pectiniger, probably since these species present extended larval development. Besides the similar morphology among species, the unique attributes presented here are important for the genus’ taxonomy, being fundamental for identifying the first larval stages of Synalpheus, as well as for subsidizing information for species identification keys. 

The dipnoan species, Sorbitorhynchus deleaskitus , from the Lower Devonian of Guangxi, China

1993 ◽  
Vol 340 (1291) ◽  
pp. 1-24 ◽  
Keyword(s):  
Lower Devonian ◽  
Early Devonian ◽  
Hyoid Arch ◽  
New Perspective ◽  
Dermal Bones ◽  
Late Emsian

A dipnoan species from the Emsian of Guangxi, China, Sorbitorhynchus deleaskitus , which has previously been diagnosed in the appendix to a more general paper on dipnoan phylogeny (Cambell & Barwick 1990), is described in detail. The head is large and heavily ossified, with cosmine on the external dermal bones. The dental plates are thick and have few poorly defined large tuberosities towards their anterolateral edges. It is the only Early Devonian dipnoan for which the full hyoid arch, gular, basibranchial, and submandibular plates are preserved, and in which the parasphenoid is clearly defined. In many features the genus is more advanced than Dipnorhynchus , but in none is it more advanced than Dipterus , apart from the loss of the buccohypophysial foramen. It gives a new perspective on late Emsian evolution of the group, and reinforces our concept of an independently developing dentine-plated line contemporaneous with a true tooth-plated line.

The ontogeny and systematics of the otarionine trilobite Otarionella from the Devonian of the Montagne Noire, France and the Maider, Morocco

2007 ◽  
Vol 145 (1) ◽  
pp. 55-71 ◽  
Author(s):  
RUDY LEROSEY-AUBRIL ◽  
RAIMUND FEIST ◽  
BRIAN D. E. CHATTERTON
Keyword(s):  
New Species ◽  
Growth Stages ◽  
Juvenile Growth ◽  
Adult Morphology ◽  
Montagne Noire ◽  
First Time ◽  
Late Emsian

AbstractA new otarionine trilobite Otarionella rastrum sp. nov., from the late Emsian Mont Peyroux Formation (Montagne Noire, France), is described. Silicified remains, recovered from the underlying Bissounel Formation (early to late Emsian), are also attributed to this new species. These isolated silicified sclerites represent metaprotaspid to young holaspid growth stages, which enables the almost complete ontogeny of an otarionine trilobite with a spinose adult morphology to be described for the first time. Comparison with associated larval and juvenile growth stages of Cyphaspis reveal that the pattern of juvenile cranidial spine distribution in Otarionella rastrum sp. nov. differs from all patterns described so far in the Otarioninae, in particular that characterizing the tribe Otarionini. A second species, Otarionella lkomalii sp. nov., known only from a complete articulated specimen discovered in the early Eifelian of southern Morocco, is also described. Like the middle Eifelian Otarionella chamaeleo (Basse, 1997), this new species has only ten thoracic segments, with the fourth and the sixth segments each bearing a long axial spine. In the light of the new elements provided by the ontogenetic sequence of O. rastrum sp. nov. and the adult specimens of this species and O. lkomalii sp. nov., the putative synonymy of Otarionella and Otarion is rejected and a restricted concept of the genus Otarionella is defined.

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