Samaroblattella valmarensis: A Subioblattid 'roachoid' from the Middle Triassic of Monte San Giorgio fauna of Switzerland.

The Eoblattodea, or 'roachoids' form a stem group to the living Dictyoptera, which comprises the Cockroaches, Mantises, and Termites (a stem group contains fossil species more closely related to the living group they are on the 'stem' of than to any other living group, but not descended from the last common ancestor of all living members of that group). This stem group first appeared in the Carboniferous, with the common ancestor of all living Dictyopterans probably living in the Jurassic. The Subioblattids are a small group of 'roachoids' known from the Triassic of South Africa, France, and Central Asia. This group is fairly well-known from its forewing anatomy (the forewings are considered to be reliable on their own for the diagnosis of Insect relationships), but to date no body fossils found to date.

In a paper published in the Swiss Journal of Palaeontology on 10 March 2025, Matteo Montagna of the Department of Agricultural Sciences at the University of Naples Federico II, Fabio Magnani of the Museo Cantonale di Storia Naturale, Giulia Magoga, also of the Department of Agricultural Sciences at the University of Naples Federico II, and André Nel of the Institut de Systématique, Évolution, Biodiversité at the National d’Histoire Naturelle, describe a new species of Subioblattid 'roachoid' from the Middle Triassic of Monte San Giorgio fauna of Switzerland.

The Monte San Giorgio fauna derives its name from Monte San Giorgio, a mountain on the border between Italy and Switzerland in the Lugano Prealps. The exposed geological sequence on this mountain begins in the Lower Permian, where a succession of volcanic rocks mark the onset of the Variscan Orogeny, as the continents of Euramerica and Gondwana collided during the formation of the supercontinent of Pangea. These are overlain by a sequence of Triassic sediments recording a tropical terrestrial environment, a shallow near-shore environment, a deeper marine basin with extensive limestone deposits, a second terrestrial exposure caused by a major marine regression (drop in sealevel) in the Late Triassic, and finally an Early Jurassic marine Basin.

The fossils of the Monte San Giorgio fauna come from shales of the Besano Formation and the overlying Meride Limestone, which were laid down in the Early-Middle Triassic marine basin. These fossils include Bivalves, Marine Reptiles, Fish, Crustaceans, and Cephalopods, as well as terrestrial-derived fossils such as Plants, terrestrial Vertebrates, and Insects. To date, 273 species of Insect have been recorded from Monte San Giorgio, including Thrips, True Bugs, and Flies, as well as representatives of groups such as the Monura and Permithonidae, which were thought to hve died out in the End Permian Extinction until they were discovered here.

Location of the Monte San Giorgio UNESCO World Heritage Site and stratigraphic section of the Middle Triassic sediments. (A0 Map showing the location of Monte San Giorgio and the carbonate Anisian-Ladinian sequence and the location of Val Mara (indicated by a star) where VM 12 site occurs. (B) Stratigraphic section of Middle Triassic sediments in Monte San Giorgio; black arrow indincates the position of VM 12 strata where the Insect fossil was collected. Montagna et al. (2025).

The new species is described from a single specimen from Meride Limestone of Monte San Giorgio. This is placed in the genus Samaroblattella on the basis of its forewing veination, but assigned to a new species, valmarensis, meaning 'from Val Mara' in reference to the location where the fossil was found.

The genus Samaroblattella was first described in 1976 to describe a fossil from South Africa, with a second species described from Kazakhstan, Central Asia, in 2001. Unlike these previously described species, and indeed all other previously described members of the roachoid family Subioblattidae, to which the genus is assigned, Samaroblattella valmarensis has a preserved body as well as wings.

The hind legs of Samaroblattella valmarensisi closely resemble those of the extant Jumping Cockroach, Saltoblattella montistabularis, with both species also having an elongate shape, and a narrow pronotum (plate on the forepart of the prothorax, before the wings) suggesting that this ancient roachoid may have had a similar jumping habit. 

However, a close relationship is not proposed, as Samaroblattella valmarensisi also has an elongated, sword-like, external ovipositor, something absent from crown group Dictyopterans (ctown group comprises all species deecended from the last common ancestor of all living species), which have an internal ovipositor. External ovipositors were found in the earliest Insects, with internal ovipositors having appeared separately several times in different groups.

Holotype of Samaroblattella valmarensis. Arrows highlight specifc body parts: f, fore legs (femora)[ ml, mid legs (femora and tibiae); hl, hind legs (femora and tibiae); ce, cerci; ov, ovipositor. Scale bar is 5 mm. Montagna et al. (2025).

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Archetingis ladinica: A Lace Bug from the Middle Triassic of the Swiss side of Monte San Giorgio.

Lace Bugs, Tingidae, are small (2-10 mm) members of the True Bug Order Hemiptera, which get their common name from the lacy pattern of the veins of their wings. They are plant parasites, with each species having a specific host, and many species are significant agricultural pests. The oldest known fossil Lace Bugs date back to the beginning of the Cretaceous, however the global distribution of the group, combined with the wides range of host plants, which includes Mosses, Conifers and Horsetails, suggests that the group was established long before the breakup of the supercontinent of Pangea in the Late Jurassic.

In a paper published in the journal Rivista Italiana di Paleontologia e Stratigrafia in March 2018, Matteo Montagna of the Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia at the Università degli Studi di Milano, Laura Strada of the Dipartimento di Scienze della Terra “Ardito Desio” at the Università degli Studi di Milano, Paride Dioli of the Museo Civico di Storia Naturale di Milano, and Andrea Tintori, also of the Dipartimento di Scienze della Terra “Ardito Desio” at the Università degli Studi di Milano, describe a new species of Lace Bug from the Swiss part of the Middle Triassic Monte San Giorgio Fossil-Lagerstätte.

The Middle Triassic Monte San Giorgio Fossil-Lagerstätte outcrops on the mountain of the same name, overlooking Lake Lugano on the Swiss-Italian Border. The site is noted for the production of Marine Vertebrates of Anisian (247-242 million years ago) to Ladinian (242-247) age, for which it has been made a UNESCO World Heritage List site. However, the site does not simply preserve marine faunas, but preserves a complex paleoenvironment with a shallow lagoon with a surrounding area that contains numerous small pools and streams, connected to a marine environment with a carbonate platform. The Lower Kalkschieferzone beds on the Swiss side of the mountain have been dated to 239.51 million years ago (Early Ladinian) and have produced several Insect fossils, including Mayflies, Beetles and Bristletails.

The new Lace Bug is named Archetingis ladinica, meaning 'Ancient Lace Bug from the Ladiaian'. It is described from a single specimen from the Lower Kalkschieferzone beds. This specimen is 11.8 mm in length, larger than any living species of Lace Bug, though many Insect groups produce fossils larger than anything still living, including Bristletails from the Kalkschieferzone.

(A) Archetingis ladinica obtained by merging slab and counterslab; (B) reconstruction of Archetingis ladinica,  features not preserved in the fossil (i.e., antennae and eyes) in grey. The white scale bar corresponds to 1 mm. Drawing by Matteo Montagna. Montagna et al. (2018).

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Preserved gastrointestinal tracts in Actinopterygian Fish from the Middle Triassic Monte San Giorgio Lagerstätte of Switzerland.

In Fish as in other animals an increased gut length  is associated with an increased amount of vegetable food in the diet, with omnivores having longer guts than carnivores, and herbivores having longer guts than omnivores. The spiral valve is a spiraled area of gut, which increases the total surface available for absorption of food, without greatly increasing the overall volume occupied by the gut. Preserved gastrointestinal tracts are rare in the fossil record, making it difficult to assess the origin of modern structures, particularly those with unusual distributions within different different taxonomic groups. A spiral valve is found in modern Sharks, Lampreys, non-Teleost Actinopterygian Fish (Bichirs, Reedfish, Sturgeon, Paddlefish, Gar and Bowfin - a total of fifty one species in four distantly related lineages) and Lungfish, while Coelocanths have a scroll valve (thought to be derived from a spiral valve). However Teleosts, Tetrapods (terrestrial Vertebrates) and Hagfish have no trace of any such structure. 

In a paper published in the journal Nature: Scientific Reports on 6 January 2015, Thodoris Argyriou of the Paleontological Institute and Museum at the University of Zurich, Marcus Clauss of the Clinic for Zoo Animals, Exotic Pets and Wildlife at the University of Zurich, Erin Maxwell of the Stuttgart State Museum of Natural History and Heinz Furrer and Marcelo Sánchez-Villagra, also of the Paleontological Institute and Museum at the University of Zurich, describe the preserved gastrointestinal tracts of three early Actinopterygian Fish from the Middle Triassic Monte San Giorgio Lagerstätte of the Tricino Canton in Switzerland. All three Fish belong to the genus Saurichthys, an extinct lineage of Pike-like Fish distantly related to Sturgeon and, Paddlefish. 

The first specimen examined is placed in the species Saurichthys costasquamosus. The specimen is almost complete, lacking only the tip of the snout. The specimen is slightly over 30 cm in length, with the largest known specimen of the species being 87 cm. Almost the complete length of the gastrointestinal tract is preserved, with about 40% of this occupied by a smaller fish of the genus Luganoia, swallowed head-first. The rear of the gut appears to include a section of spiral intestine interpreted as a spiral valve with more than 17 turns.

(a) Saurichthys costasquamosus with undigested Actinopterygian prey (cf. Luganoia) followed by a three dimensional spiral cololite. The area of interest is delineated by a box. (b) Interpretative drawing of the area of interest of the previous specimen. Scales of the midlateral row were omitted. Abbreviations are as follows: ant.int.: anterior intestine; C.F.: caudal fin of the contained prey; mv.: medioventral scale row; N.: neurocranium of the contained prey; n.a.: neural arch-like elements; vl: ventrolateral scale row. Scale bars equal 1 cm. Argyriou et al. (2015).

The second specimen is assigned to the species Saurichthys macrocephalus. It is coiled into an 'S' shape with the head detached and has an estimated body length of 24 cm, compared to 66 cm in the largest known specimen of the species. The gastrointestinal tract is preserved as a white ribbon running through the body cavity, divided into a number of segments interpreted as a stomach, a short anterior intestine and a spiral intestine with approximately 17 turns.

(c) Saurichthys macrocephalus, photographed under UV light, with a two dimensional cololite present, extending from the stomach to the spiral intestine. The area of interest is delineated by a box; (d) interpretative drawing of the area of interest around the cololite. Abbreviations are as follows: ant.int.: anterior intestine; mv.: medioventral scale row; n.a.: neural arch-like elements; vl: ventrolateral scale row. Scale bars equal 1 cm. Argyriou et al. (2015).

The third specimen described is assigned to the species Saurichthys paucitrichus. It is has an estimated length of 21 cm, with the post-gastrilc portion of the gastrointestinal tract preserved in three dimensions. The spiral section of the intestine has about 30 turns, and spans approximately 14 vertebral segments.

(a) Saurichthys paucitrichus with a three dimensional intestinal cololite preserved in situ, the area of interest is delineated by a box; (b) Detail of the area of interest containing the spiral cololite in the previous specimen; (c) Interpretative drawing of the spiral cololite of the previous specimen. Abbreviations are as follows: ant.int.: anterior intestine; mv.: medioventral scale row; n.a.: neural arch-like elements; plv.: pelvic bone; vl: ventrolateral scale row. All scale bars equal 1 cm. Argyriou et al. (2015).

The spiral glands of all three specimens are exceptionally long compared to those of modern species of similar size. A longer spiral gland could be associated with a herbivorous diet, but nothing about the morphology of Saurichthys suggests such a habit; one of the examined specimens even has a large prey item in its foregut. Alternatively the elongate spiral gland could be an adaptation to a very high energy lifestyle, such as seen in pelagic Fish which actively chase down their prey. However Saurichthys  does not appear to have been adapted to such a lifestyle either; they are similar in shape to modern Pike, which are ambush predators, and evidence has been found that some species attacked Pterosaurs, flying animals which no Fish could have chased down but which could have been targeted by an ambush predator.

Phylogenetic framework of gastrointestinal tract morphology and spiral valve turn counts of Actinopterygians, including Saurichthys paucitrichus. All drawings depict the gastrointestinal tracts in ventral view with foregut to the left and hindgut to the right. Argyriou et al. (2015).

The Saurichthyiformes (the group to which Saurichthys belonged) first appeared in the Permian, and where for the most part quite large Fish. Saurichthys is thought to have thought to have been descended from larger species. Argyrion et al. therefore suggest that the long spiral gland may have been a trait retained from this larger ancestor, rather then an adaptation to its lifestyle.

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