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| Alderblattina simmsi Swaby, Coe & Ross, 2024 |
Abstract
We describe the seventh valid species of cockroach, Alderblattina simmsi gen. et sp. nov., from insect-rich strata recording the Toarcian Oceanic Anoxic Event (T-OAE). The T-OAE represents a period of extreme global warming and environmental change that drove palaeoecological pressures and evolutionary changes in marine and terrestrial ecosystems. Here, for the first time, we present evidence that this event may also be the driver for the evolution of aposematic colouration, a predator deterrent, in cockroaches. The specimen, an isolated compressed tegmen, was collected at Alderton Hill, Gloucestershire, UK, and is assigned to a new genus and species, based on the following unique combination of characteristics: small forewing; 15 branches of R and 11 branches of M + CuA; strong cross-vein between R and M; intercalaries; and two well-defined subspherical maculae (spots) and colouration at the wing tip. Alderblattina simmsi is assigned to the family Rhipidoblattinidae Rohdendorf, primarily based on its small size and the presence of branched anal veins in the clavus. The colouration present on A. simmsi represents the first recorded likely occurrence of aposematism in cockroaches, and provides evidence for the evolution of colour patterning in Blattodea.
Keywords: Alderblattina simmsi, Blattodea, Rhipidoblattinidae, Alderton Hill, Toarcian Oceanic Anoxic Event, aposematic colouration
SYSTEMATIC PALAEONTOLOGY
Order BLATTODEA Brunner Von Wattenwyl, 1882
Superfamily CALOBLATTINOIDEA Vršanský, 2000
Family RHIPIDOBLATTINIDAE Rohdendorf, 1949
Type genus: Rhipidoblattina Handlirsch, 1906.
Type species: Mesoblattina geikiei Scudder, 1886, p.454.
Diagnosis: Small cockroaches with a curved radius, intercalaries and a clavus with bifurcating anal veins.
Genus Alderblattina nov.
Derivation of name: The genus is named after Alderton Hill, the locality from which the specimen was derived.
Alderblattina simmsi sp. nov.
Derivation of name: The species is named after geologist Michael J. Simms, who originally collected the specimen while working in the field with Edmund A. Jarzembowski in January 1984.
Diagnosis: Small forewing; 15 branches of R and 11 branches of M + CuA; strong cross-vein between R and M; two subspherical maculae (spots) in the medial area and colouration at wing tip; A1 terminates on CuP.
Emily J. Swaby, Angela L. Coe and Andrew J. Ross. 2024. A New Cockroach (Blattodea, Rhipidoblattinidae) from the Toarcian (Lower Jurassic) of Alderton Hill, Gloucestershire, UK, and the earliest likely occurrence of aposematic colouration in Cockroaches. Papers in Palaeontology. DOI: doi.org/10.1002/spp2.1598
