Phylogenetic analysis of the Squilloidea (Crustacea:Stomatopoda)

2005 ◽  
Vol 19 (3) ◽  
pp. 189 ◽  
Author(s):  
Shane T. Ahyong

Squilloidea is the most speciose of the stomatopod superfamilies and comprises more than 40 genera. Until 2001, three families were recognised: two extant (Harpiosquillidae, Squillidae) and one extinct (Ursquillidae). Recent studies, however, suggested that Harpiosquillidae is nested among other squillids and was thus synonymised with Squillidae. Interrelationships of all squilloid genera are studied by cladistic analysis based on somatic morphology. Results are used to assess the familial classification and investigate the ‘shape’ of squilloid evolution. The phylogeny of the squilloids shows general trends in the armature of the raptorial claw, increased dorsal carination, a tendency for bilobation of the lateral processes of the exposed thoracic somites, and a change in telson shape from trianguloid with movable submedian teeth, to quadriform with fixed submedian teeth. Harpiosquilla Holthuis, 1964 is deeply nested among other squillid genera, supporting the recent synonymy of the Squillidae and Harpiosquillidae. Characters of the late Cretaceous Ursquillidae show that it is highly derived and is therefore synonymised with Squillidae. Although the antiquity of Ursquilla Hof, 1998 does not show it to be a basal or stem-lineage squilloid, it does show that the squilloids had already undergone significant diversification by the end of the Cretaceous. Species of most squilloid genera are regionally restricted, either to the Indo-west Pacific or Atlanto-east Pacific. Only Alima Leach, 1818, Cloridopsis Manning 1968b, and Pontiosquilla Manning, 1995 are represented in both regions.

2000 ◽  
Vol 48 (6) ◽  
pp. 607 ◽  
Author(s):  
Shane T. Ahyong ◽  
Christine Harling

The stomatopods, or mantis shrimps, are malacostracan crustaceans of the subclass Hoplocarida. Extant hoplocarids belong to the order Stomatopoda and suborder Unipeltata, comprising the extinct, stem-lineage pseudosculdids and sculdids, and the crown group. Cladistic analysis including most or all genera of the unipeltatan families, and rooted to the extinct Tyrannophontidae, resulted in four most-parsimonious cladograms. The present results are more highly resolved and more robust than previous studies as the result of: more precise identification of suitable outgroups; a more complete outgroup data set, lessening the impact of missing data; and increased taxonomic sampling. The results largely support the existing five-superfamily classification, but as with two recent cladistic studies, Gonodactyloidea was polyphyletic. Gonodactyloidea is the basal crown-group superfamily and comprises mostly ‘smashers’. Two clades of ‘spearers’, Eurysquillidae and Parasquillidae, previously considered gonodactyloids, are more closely related to the Squilloidea and are referred to new superfamilies. The familial classification within Lysiosquilloidea is modified. Rather than deriving the ‘smashers’ from a long line of ‘spearers’, the present analysis suggests that the Unipeltata diverged in two broad directions from the outset. Hence, the gonodactyloid ‘smashers’ became specialised for hard substrates, and the remainder diversified into the other modern superfamilies, evolving more efficient ‘spearing’ claws, and occupying soft substrates.


2018 ◽  
Vol 49 (2) ◽  
pp. 103-129 ◽  
Author(s):  
Rogério Botion Lopes ◽  
Fernando Barbosa Noll

Zethus is the largest genus in Eumeninae, with over 250 species. Currently, it is divided in four subgenera: Z. (Zethus), Z. (Zethusculus), Z. (Zethoides) and Z. (Madecazethus). Z. (Zethoides), with 42 species, is subdivided in eight species groups, each considered a phylogenetic unit, that were created without any phylogenetic analysis. Eighteen species of Z. (Zethoides) corresponding to different groups were examined, altogether with terminals from distinct lineages of Zethus, Zethini and Eumenini, to perform a cladistics analysis to verify the proposed divisions. Zethus (Zethoides) and all of its species groups, except for the Z. biglumis group, were monophyletic. Zethus s.s. was paraphyletic in relation to Z. (Madecazethus), Z. (Zethoides) and Ctenochilus. Z. (Zethusculus) was also retrieved paraphyletic. Despite the subgeneric incongruences, the outgroups were too poorly represented to carry a taxonomic modification. Thus, the only alteration was the inclusion of the Z. clypearis group in the Z. biglumis group.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2502 ◽  
Author(s):  
Walter G. Joyce ◽  
Tyler R. Lyson ◽  
James I. Kirkland

BackgroundBothremydidae is a clade of extinct pleurodiran turtles known from the Cretaceous to Paleogene of Africa, Europe, India, Madagascar, and North and South America. The group is most diverse during the Late Cretaceous to Paleogene of Africa. Little is known, however, about the early evolution of the group.MethodsWe here figure and describe a fossil turtle from early Late Cretaceous deposits exposed at MacFarlane Mine in Cedar Canyon, southwestern Utah, USA. The sediments associated with the new turtle are utilized to infer its stratigraphic provenience and the depositional settings in which it was deposited. The fossil is compared to previously described fossil pleurodires, integrated into a modified phylogenetic analysis of pelomedusoid turtles, and the biogeography of bothremydid turtles is reassessed. In light of the novel phylogenetic hypotheses, six previously established taxon names are converted to phylogenetically defined clade names to aid communication.ResultsThe new fossil turtle can be inferred with confidence to have originated from a brackish water facies within the late Cenomanian Culver Coal Zone of the Naturita Formation. The fossil can be distinguished from all other previously described pleurodires and is therefore designated as a new taxon,Paiutemys tibertgen. et. sp. nov. Phylogenetic analysis places the new taxon as sister to the EuropeanPolysternon provinciale,Foxemys trabantiandFoxemys mechinorumat the base of Bothremydinae. Biogeographic analysis suggests that bothremydids originated as continental turtles in Gondwana, but that bothremydines adapted to near-shore marine conditions and therefore should be seen as having a circum-Atlantic distribution.


1998 ◽  
Vol 67 (4) ◽  
pp. 237-255 ◽  
Author(s):  
G.A. Bishop ◽  
R.M. Feldmann ◽  
F. Vega

The podotrematous crab family Dakoticancridae includes four genera: Dakoticancer Rathbun, Tetracarcinus Weller, Avitelmessus Rathbun, and Seorsus Bishop, all known solely from the Late Cretaceous of North America. Lathelicocarcinus Bishop, originally referred to the family, must be reassigned. Fine details of anatomy, preserved on specimens of D. overanus Rathbun and A. grapsoideus Rathbun, permit description of genital openings and interpretation of functional morphology of appendages. Although one species, D. australis Rathbun, has been found associated with burrow structures, all were probably vagrant epifaunal animals on fine- to medium-grained siliciclastic substrata. Food was probably obtained by generalized low-level predation and scavenging. Results of a cladistic analysis are consistent with the stratigraphic data suggesting that T. subquadrata Weller is nearest the rootstock of the family and that other taxa within the family are derived from it.


2007 ◽  
Vol 38 (3) ◽  
pp. 335-359 ◽  
Author(s):  
Sergio Roig-Juñent ◽  
Martha Domínguez ◽  
Federico Agrain

AbstractThe subgenus M. (Scaphigenia) Lacordaire includes six species distributed in arid regions of South America. A systematic revision of this subgenus is presented, including re-descriptions and an update of distribution data of the six species. A preliminary cladistic analysis is performed to test the relationships among the species of the subgenus and if the morphological characters used are suitable. A key is presented to separate the seven subgenera of Megalostomis Chevrolat as well as a key for the species of the subgenus M. (Scaphigenia). Male aedeagus internal sac of the nine studied taxa are described and illustrated. This constitutes the first internal sac descriptions for members of this subtribe and could help clarify the homology of such structures within Cryptocephalinae. M. (S) consimilis Achard is reassigned to the species status on the base of genitalic characters. The cladistic analysis was done using forty-one characters from adult external morphology and male and female genitalia. Two species of two different subgenera of Megalostomis: M. (Megalostomis), and M. (Heterostomis) Lacordaire, and one representative of the genus Themesia Lacordaire were selected as out groups. Results were obtained by implicit enumeration using parsimony software. Three equally parsimonious trees were obtained of 45 steps, Ri=0.952, and Ci= 0.941. Support of each group was evaluated by Jacknifing, Bootstrap and Bremer values. Relationships between species are discussed.


2019 ◽  
Vol 286 (1912) ◽  
pp. 20191336 ◽  
Author(s):  
Linda Frey ◽  
Michael Coates ◽  
Michał Ginter ◽  
Vachik Hairapetian ◽  
Martin Rücklin ◽  
...  

Anatomical knowledge of early chondrichthyans and estimates of their phylogeny are improving, but many taxa are still known only from microremains. The nearly cosmopolitan and regionally abundant Devonian genus Phoebodus has long been known solely from isolated teeth and fin spines. Here, we report the first skeletal remains of Phoebodus from the Famennian (Late Devonian) of the Maïder region of Morocco, revealing an anguilliform body, specialized braincase, hyoid arch, elongate jaws and rostrum, complementing its characteristic dentition and ctenacanth fin spines preceding both dorsal fins. Several of these features corroborate a likely close relationship with the Carboniferous species Thrinacodus gracia , and phylogenetic analysis places both taxa securely as members of the elasmobranch stem lineage. Identified as such, phoebodont teeth provide a plausible marker for range extension of the elasmobranchs into the Middle Devonian, thus providing a new minimum date for the origin of the chondrichthyan crown-group. Among pre-Carboniferous jawed vertebrates, the anguilliform body shape of Phoebodus is unprecedented, and its specialized anatomy is, in several respects, most easily compared with the modern frilled shark Chlamydoselachus . These results add greatly to the morphological, and by implication ecological, disparity of the earliest elasmobranchs.


2020 ◽  
Vol 6 (10) ◽  
pp. eaay1259
Author(s):  
Xiangdong Zhao ◽  
Bo Wang ◽  
Alexey S. Bashkuev ◽  
Cédric Aria ◽  
Qingqing Zhang ◽  
...  

Mesozoic long-proboscid scorpionflies (Mesopsychoidea) provide important clues to ancient plant-pollinator interactions. Among them, the family Aneuretopsychidae is especially important because its mouthparts are vital to deciphering the early evolution of Mesopsychoidea and putatively the origin of fleas (Siphonaptera). However, the identification of mouthpart homologs among Aneuretopsychidae remains controversial because of the lack of three-dimensional anatomical data. Here, we report the first Aneuretopsychidae from Late Cretaceous Burmese amber, which have short maxillary palpi and elongate mouthpart elements consisting of one pair of galeae and one hypopharynx. Their mouthparts are identical to those of Pseudopolycentropodidae (= Dualulidae, new synonym) but are not homologous to those of Siphonaptera. Our phylogenetic analysis provides robust evidence for the debated monophyly of Mesopsychoidea. Our results suggest that the long-proboscid condition has most likely evolved once in Mesopsychoidea, independently from fleas, and further reveal the variety and complexity of mid-Cretaceous pollinating insects.


2020 ◽  
Vol 7 (10) ◽  
pp. 201184
Author(s):  
Gregory F. Funston ◽  
Tsogtbaatar Chinzorig ◽  
Khishigjav Tsogtbaatar ◽  
Yoshitsugu Kobayashi ◽  
Corwin Sullivan ◽  
...  

Late Cretaceous trends in Asian dinosaur diversity are poorly understood, but recent discoveries have documented a radiation of oviraptorosaur theropods in China and Mongolia. However, little work has addressed the factors that facilitated this diversification. A new oviraptorid from the Late Cretaceous of Mongolia sheds light on the evolution of the forelimb, which appears to have played a role in the radiation of oviraptorosaurs. Surprisingly, the reduced arm has only two functional digits, highlighting a previously unrecognized occurrence of digit loss in theropods. Phylogenetic analysis shows that the onset of this reduction coincides with the radiation of heyuannine oviraptorids, following dispersal from southern China into the Gobi region. This suggests expansion into a new niche in the Gobi region, which relied less on the elongate, grasping forelimbs inherited by oviraptorosaurs. Variation in forelimb length and manus morphology provides another example of niche partitioning in oviraptorosaurs, which may have made possible their incredible diversity in the latest Cretaceous of Asia.


2020 ◽  
pp. 1-45
Author(s):  
Bruno Zilberman

Corotoca is a strictly Neotropical genus of termitophilous beetles associated with termites of genus Constrictotermes. A cladistic analysis based on 13 terminal taxa and 60 characters (57 morphological and three behavioral) was conducted. The exhaustive search with equally weighted characters resulted in two most parsimonious trees with 95 steps. Spirachtha is proposed to be the sister group of the monophyletic “subgroup Corotocae” (Corotoca + Cavifonexus gen. nov.), based on eleven synapomorhphies (ten exclusive and one homoplastic). The monophyly of Corotoca is supported here, including six species associated with Constrictotermes cyphergaster: (Corotoca hitchensi sp. nov + (C. melantho + C. pseudomelantho sp. nov.) + ((C. fontesi + (C. phylo + C. araujoi)). A new genus, Cavifronexus gen. nov., is proposed to two species associated with Constrictotermes cavifrons (Holmgren, 1910): Cavifronexus guyanae comb. nov., from Guyana and Brazil, previously described as Corotoca; and a new species, Cavifronexus papaveroi sp. nov., from Brazil. This work also includes descriptions, redescriptions, and illustrations for all species and genera. Keys for genera and species identification in “subgroup Corotocae” are also provided.


2003 ◽  
Vol 77 (5) ◽  
pp. 876-887 ◽  
Author(s):  
Kazushige Tanabe ◽  
Neil H. Landman ◽  
Yuki Yoshioka

Intra- and interspecific variation in the early internal shell features of ammonoids has been examined in 14 Late Cretaceous species representing four suborders on the basis of large samples from Hokkaido (Japan) and the U.S. Western Interior Province. Our observations indicate that quantitative characters such as the size of the initial chamber and ammonitella, the length of the prosiphon, and the ammonitella angle exhibit moderate variation within species. The ranges of variation partly overlap among species, indicating that these characters are not suitable for studies of the higher-level systematics of ammonoids, but may sometimes help diagnose species. In contrast, there is much less variation within species with respect to qualitative characters such as the shape of the prosiphon, the presence or absence of accessory threads of the prosiphon, the shape of the caecum, and the initial position of the siphuncle. Examination of these characters shows that they appear to be stable at the superfamily level for the Ammonitina, but variable among species in the Lytoceratina. Thus, these characters are potentially more useful for higher-level phylogenetic analysis.


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