Stenichnus

Abstract: Subgenera of the speciose ant-like stone beetle genus Stenichnus Thomson are revised. The genus is re-classified and only two subgenera are retained: Stenichnus s. str. and Scydmaenichnus Reitter. Two remaining subgenera, Austrostenichnus Franz and Scydmaenilla King, are elevated to the genus rank (the status of Scydmaenilla , originally described as a genus and later reduced to a subgenus of Stenichnus , is restored). Two species occurring in New Zealand, Stenichnus insignis (Broun) and Stenichnus kuschelianus Franz, previously classified in Stenichnus ( Austrostenichnus ), are placed in a separate genus Zeanichnus gen. nov. (with Scydmaenus insignis Broun as a type species). Scydmaenilla is divided into two subgenera: Scydmaenilla s. str. and Scydmaenillunia subg. nov. (with Scydmaenilla adelaidensis Franz as a type species). Lectotypes are designated for Stenichnus ( Scydmaenichnus ) fossifrons Reitter, Scydmaenilla pusilla King and Scydmaenilla constricta Lea. All Australo-Pacific species, previously placed in Stenichnus , are redescribed: Austrostenichnus caledonicus Franz (New Caledonia), Zeanichnus insignis (Broun) comb. nov. (New Zealand), Zeanichnus kuschelianus (Franz) comb. nov. (New Zealand), Scydmaenilla (s. str.) pusilla King, stat. rest. (Australia), S. (s. str.) constricta Lea, stat. rest. (Tasmania), S. (s. str.) queenslandica Franz (Australia), S. (s. str.) thompsoniana Franz (Australia), S. (s. str.) brisbanensis Franz (Australia), S. (s. str.) sydneyana Franz (Australia), and S. ( Scydmaenillunia ) adelaidensis Franz (Australia). A possible synonymy of Scydmaenilla queenslandica and S. thompsoniana is discussed, not possible to verify on the basis of the available material.

Abstract: The first detailed description of Early Permian tetrapod trackways from the Cedar Mesa Sandstone is presented. A unique specimen from exposures along the Dirty Devil River north of Hite, Utah was photographed and molded in latex as a rescue mission prior to flooding of the lower end of the Dirty Devil Drainage following the construction of Glen Canyon Dam. The salvaged trackway segments are particularly interesting because they appear to show a large trackmaker (cf. ichnogenus Anomalopus) snapping up a smaller animal (cf. Stenichnus). We interpret this as evidence of a pelyco‐saurian predator eating or carrying off a smaller reptile. Direct evidence of predator‐prey relationships based on vertebrate trackways is very rare. These trackways therefore provide an unusual opportunity to study interaction between two species of Permian vertebrates. Although such trackway evidence of predator‐prey interactions has occasionally been reported from the fossil footprint record, it is rare, and previously reported ex...

Abstract: The mature larva of Stenichnus godarti is redescribed on the basis of a shed larval skin; identification was made by rearing the adult. New data on the life history of St. godarti are provided, including feeding behavior of the larva and adult and longevity of the adult under laboratory conditions. Possible serial homology of chaetotaxic structures across body segments is discussed, and morphological structures of immature St. godarti are compared with those of previously described St. collaris . It is concluded that despite structural similarities and some chaetotaxic structures (mainly on the antennae, mouthparts, legs and thoracic sternites) shared by St. godarti and St. collaris , differences in some important body regions are so profound that it is difficult to draw homologies between setal pattern on the head, thoracic and most of the abdominal tergites, based solely on topological evidence. Differences in the chaetotaxy of the head are especially puzzling and a hypothesis of displaced frontal arms of the epicranial suture is proposed, assuming homology between the presutural setae of St. godarti with postsutural setae of St. collaris . Furthermore, alternative interpretations of dorsal thoracic setae are discussed.