Tarsal Morphology Research Articles

A new species of Tricorythodes Ulmer, 1920 (Ephemeroptera: Leptohyphidae) and first record of Tricorythodes quizeri Molineri, 2002 from Brazil

A new species of Tricorythodes Ulmer, 1920 (Ephemeroptera: Leptohyphidae) is described and illustrated based on larvae from Brazil. Tricorythodes sallesi sp. nov. is distinguished from other species of the genus due to the presence of a distinctive spine-like anterolateral projection of the pronotum, besides its tarsal claw morphology and colouration pattern. In addition, the species Tricorythodes quizeri Molineri, 2002 is recorded for the first time from Brazil. Habitat and ecological information associated with these two species are commented.

Tarsal morphology and attachment ability of the codling moth Cydia pomonella L. (Lepidoptera, Tortricidae) to smooth surfaces

Despite several studies on the attachment ability of different insect taxa, little is known about this phenomenon in adult Lepidoptera. In this study we combined morphological and experimental analyses of tarsal adhesive devices and the attachment ability of the codling moth Cydia pomonella (L.) (Lepidoptera, Tortricidae) to smooth surfaces. Pretarsi of C. pomonella attach to smooth substrates by means of their smooth, flexible and well developed arolia. Using the centrifugal force measurement technique, friction forces of males and females were assessed on hydrophobic and hydrophilic glass surfaces. Adults of both sexes generated similar forces in spite of the noticeable difference in their body masses. That is why males showed significantly higher safety factors (attachment force divided by body weight) compared to those of females. Hydrophobicity of the substrate had no considerable effect on friction forces. For females, friction forces (sliding parallel to the substrate plane) were compared with adhesive forces (pulling off perpendicularly from the substrate plane) measured on Plexiglas surfaces. It can be concluded that the attachment system of C. pomonella is rather robust against physico-chemical properties of the substrate and is able to achieve a very good attachment on vertical and horizontal substrata.

Asian gliriform origin for arctostylopid mammals

Arctostylopids are common in Late Palaeocene and Early Eocene mammal faunas of Asia, but they are rare in North America. From the time of their first discovery, arctostylopids were grouped with the strictly endemic South American Notoungulata based on their strikingly similar dental morphology. This relationship was challenged based on dental morphology of more recently discovered arctostylopids and on supposed tarsal morphology (based on unassociated material) of the Asian arctostylopid Palaeostylops. Therefore, Arctostylopidae were placed in a separate order, Arctostylopida, of enigmatic affinities. Many authors, however, continue to unite Arctostylopidae and Notoungulata based on dental similarities. In the Late Palaeocene Subeng site in Inner Mongolia, we identified the Palaeostylops tarsals based on their size and abundance. This identification is supported by comparison to unpublished Arctostylops tarsals from the North American Clarkforkian, derived from a semi-articulated skeleton also including dental material. Tarsal morphology shows moderate similarity to the gliriform Pseudictops, and strong resemblance to the tarsally conservative gliroid Rhombomylus. Hence, Arctostylopidae may best be grouped with Asian non-gliroid Gliriformes, which we interpret as having dispersed into North America in the Late Palaeocene.

Foot bones from Omo: Implications for hominid evolution

We reanalyze a hominid talus and calcaneus from Omo dating to 2.2 mya and 2.36 mya, respectively. Although both specimens occur at different localities and times, both tarsals articulate well together, suggesting a single taxon on the basis of size and function. We attribute these foot bones to early Homo on the basis of their morphology. The more modern-like tarsal morphology of these Omo foot bones makes them very similar to a talus from Koobi Fora (KNM-ER 813), a specimen attributed to Homo rudolfensis or Homo erectus. Although the Omo tarsals are a million years younger than the oldest known foot bones from Hadar, both localities demonstrate anatomical differences representing two distinct morphological patterns. Although all known hominid tarsals demonstrate clear bipedal features, the tarsal features noted below suggest that biomechanical changes did occur over time, and that certain features are associated with different hominid lineages (especially the robust australopithecines).

The Tarsal Complex of Afro-Malagasy Tenrecoidea: A Search for Phylogenetically Meaningful Characters

Morphological characters should be assessed in an ecological and evolutionary framework before their use in phylogenetic analyses. We have attempted such an assessment for the tarsal complex of the Tenrecoidea. The 30+/− extant species of these small mammals live in a diverse range of microhabitats. They exhibit markedly different positional behaviors, encompassing four basic locomotor repertoires: terrestrial running and walking, scansorial climbing, digging, and swimming. Articular surfaces from the upper, middle, and lower ankle joints in 10 Malagasy tenrecid, 1 potamogalid, 1 solenodontid, and 1 macroscelidid species were compared. The results were tested against published data on the correlation between function and morphology in other therian locomotor specialists. Descriptive accounts, supported by quantitative analyses, demonstrate significant differences in many aspects of tarsal morphology that may be explained by function-based hypotheses within the context of the tenrecoid heritage. Three closely related tenrecines (Hemicentetes, Setifer, and Echinops) show divergences in form that are consistent with their respective semifossorial, terrestrial, and scansorial/arboreal modes of locomotion. In addition to functional–adaptive considerations, we propose several synapomorphies for the tenrecine and oryzorictine clades that appear to corroborate their monophyly. There are apparent convergences between the habitual diggers from different subfamilies (Hemicentetes and Oryzorictes), and there are adaptive differences within subfamilies (e.g. arboreal Echinops vs. terrestrial Setifer). The few likenesses between Potamogale and Limnogale cannot be supported as homologies, and the proposal of a recent phylogenetic affiliation between them is therefore rejected here. Manifest differences in tarsal form between Geogale and the oryzorictines support recognition of the subfamily Geogalinae. As expected, the tarsal complex of Solenodon is fundamentally unlike that of the tenrecoids. Finally, the similarities in detail between Macroscelididae and Potamogalidae reflect the stabilization of UAJ during plantarflexion, and therefore such attributes are rejected as synapomorphies. Traits with clear species-specific adaptations are a potential interference in cladistic analyses and cannot be meaningfully used without ecology-based character assessment. While this practice may ultimately reduce the size of a database, it will nonetheless result in taxonomic properties with lasting value against which phylogenetic hypotheses may be tested with confidence.

A REVIEW OF THE CHINESE PSECHRIDAE (ARANEAE)

The Chinese psechrid spiders of the genera Fecenia and Psechrus are reviewed. The species Fecenia hainanensis is newly synonymized with F. cylindrata. The species P. mimus is considered a nomen dubium. The species P. senoculata is regarded as a valid species. The male is newly described for P. tingpingensis. Three new species are described: P. jinggangensis new species, P. rani new species, and P. taiwanensis new species. In all, nine psechrid species are recognized from China. The spinnerets, trichobothria, and tarsal organ morphology of P. tingpingensis are presented. A key to Chinese Psechrus species is also provided.

A New Marsupial from the Early Eocene Tingamarra Local Fauna of Murgon, Southeastern Queensland: A Prototypical Australian Marsupial?

Djarthia murgonensis, a new genus and species of marsupial from the early Eocene Tingamarra Local Fauna of Murgon in southeastern Queensland, is described on the basis of dental material. The combination of marsupial synapomorphies and symplesiomorphies present in D. murgonensis suggests phylogenetic placement within either Didelphidae or Australidelphia. Tarsal morphology, fundamental to the concepts of Ameridelphia and Australidelphia respectively, is not yet known for this taxon. Consequently, it cannot be assigned to either clade with confidence. If this taxon is australidelphian, it constitutes support for the hypothesis that the common ancestor of the Australian marsupial radiation was didelphoid-like in dental features. Some previous authors have contended that marsupial faunas of South America and Australia are manifestly distinct, excepting for the australidelphian affinity of South American microbiotheres. However, because tarsal anatomy is unknown in some generalized Australian fossil taxa, including D. murgonensis, and character analysis reveals that no synapomorphies of the dentition unequivocally define either Ameridelphia or Australidelphia to the exclusion of the other, we consider this interpretation to be premature. In short, available evidence neither supports nor refutes the argument of distinct South American and Australasian marsupial faunas. A further ramification is the need to reconsider the phylogenetic position of Ankotarinja tirarensis and Keeuna woodburnei. These central Australian fossil taxa might be referred to either Australidelphia or Ameridelphia, and it is recommended that both be treated as Marsupialia incertae sedis until further material comes to light.

Does archosaur phylogeny hinge on the ankle joint?

ABSTRACT Cladistic phylogenies of the archosaur ingroup are reviewed in light of recent concerns regarding an over-dependence on characters relating to tarsal and pedal morphology. The use of simple statistical techniques shows that the exclusion of ankle characters from recent cladistic phylogenies has no significant effect on the relative support of relationships proposed. Contrary to current opinion, ankle characters should be considered unimportant when attempting to reconstruct the broad shape of archosaur phylogeny.

The tarsus of erythrosuchid archosaurs, and implications for early diapsid phylogeny

Abstract The morphology of the erythrosuchid ankle joint is reassessed. Two specimens, recently thought to have been incorrectly referred toErythrosuchus africanus, are shown without doubt to belong to this taxon. Furthermore, the morphology is essentially similar to that of other early archosaurs. The tarsus ofErythrosuchusis poorly ossified and consists of a calcaneum, astragalus, and two distal tarsals. The calcanea ofErythrosuchus, Vjushkovia triplicostata, andShansisuchus shansisuchusare all similar in being dorsoventrally compressed, possessing a lateral tuber, and lacking a perforating foramen. The astragalus ofV. triplicostatais currently unknown. The astragalus ofShansisuchusis apparently unique in form. The erythrosuchid pes is therefore more derived than has been recently proposed. The tarsal morphology of several other archosauromorph taxa is reviewed and many details are found to be at variance with the literature. The plesiomorphic condition for the Archosauromorpha consists of four distal tarsals and a proximal row of three elements; two of which articulate with the tibia. These proximal elements are interpreted as the astragalus, calcaneum, and a centrale, and the same pattern is retained in the earliest archosaurs. This reassessed tarsal morphology has implications for the homology of the centrale and reconstruction of early diapsid phylogeny.

Eutherian tarsal bones from the Late Cretaceous of India

Eutherian tarsal bones of Late Cretaceous age are reported for the first time from sedimentary beds intercalated with the Deccan Traps of peninsular India. The tarsal bones, represented mainly by calcanea and astragali, occur in association with dental elements of palaeoryctid mammals:Deccanolestes hislopiPrasad and Sahni andD. robustusPrasad, Jaeger, Sahni, Gheerbrant, and Khajuria. Two size variants in the tarsals correlate well with the teeth ofD. hislopiandD. robustus.Morphologically, the tarsal complex ofDeccanolestesis quite different from that of other Cretaceous eutherians for which the relevant anatomy is known (ProtungulatumandProcerberus). Rather, the tarsals ofDeccanolestesexhibit a close affinity to the tarsal morphology of Archonta. A large number of tarsal characters indicate a highly arboreal mode of life for these animals. Presence of such specialized animals as early as the Cretaceous suggests that mammals had already diversified their locomotor adaptations by this time.