Austaulius haustrum: A new species of Necrotaulid Caddisfly from the Early Jurassic of Lyme Regis, England.

Caddisflies, Trichoptera, are a widespread and numerous (over 12 000 described species) group of Insects closely related to the Lepidoptera (Butterflies and Moths). Like Butterflies and Moths, Caddisflies undergo a complete metamorphosis upon reaching maturity, with a long-lived caterpillar-like larvae, and a shorter-lived flying adult stages (which typically lives one-to-two weeks). However, unlike the larvae of Butterflies and Moths, Caddisfly larvae are entirely aquatic, with only the winged adults emerging above the water surface. Most larval Caddisfly inhabit cases which they make out of silk, which some species are noted for covering with small stones, pieces of plant matter, shells or other matter they find in their environment. The larvae may be herbivorous or carnivorous, adult Caddisfly generally do not eat at all. They have a fossil record dating back to the Triassic.

The Necrotauliidae are a curious group of Caddisflies known from the Triassic and Jurassic of Europe, Asia and Australia. Their wing venetion sugests that they are members of the Trichoptera, but they have a number of un-Caddifly-like characteristics, including scales on their wings, a trait generally associated with the Lepidoptera. As such their is some dispute about the classification of this group, with some palaeoentomologists regarding them as early members of the Lepidoptera, others as a stem group from which both the Lepidoptera and the Trichoptera are descended, and while most experts do accept them to be Caddisflies, they differ in whether they are a distinct group that branched off early in the history of the Trichoptera, or a polyphyletic assemblage of early Caddisflies from which the more modern groups are descended.

In a paper published in the journal Psyche on 9 May 2018, Richard Kelly of the School of Earth Sciences at the University of Bristol, and the Department of Natural Sciences at the National Museum of Scotland, Andrew Ross, also of the Department of Natural Sciences at the National Museum of Scotland, and of the Department of Earth Sciences at the Natural History Museum, and Robert Coram, also of the School of Earth Sciences at the University of Bristol, and of British Fossils, describe a new species of Necrotaulid Caddisfly from the Early Jurassic of Lyme Regis, England, as part of a review of the Necrotaulid Caddisflies of the Triassic and Jurassic of England.

The new species is placed in the genus Austaulius, which is created by the authors of the paper to include a number of previously described species, including the Australian Prorhyacophila colliveri (now Austaulius colliveri), which as the oldest described species assigned to the new genus is taken as its type species, the name 'Austaulius' referring to this, and given the specific name haustrum, in reference to the mouthparts of the species, which form a sucking proboscis. The species is described from a single specimen collected from Monmouth Beach at Lyme Regis. This specimen has both forewings and a partial hind wing, as well as the thorax, head, some antennomeres, some leg segments, the maxillary and labial palps, and the haustellum.

Austaulius haustrum from Monmouth Beach, Lyme Regis, Dorset. Bottom left figure is the right forewing of the specimen flipped so the costal margin is on top. Scale bars are 1 mm. Kelly et al. (2018).

See also...

Follow Sciency Thoughts on Facebook.

Monmouth Beach, Lyme, closed due to danger of landslips.

Monmouth Beach lies to the west of Lyme Harbour, on the Jurassic Coast of Dorset. It is popular with tourists due to its Limestone Pavement, where abundant large Ammonites can be seen, and the ease with which detached fossils can be found on the foreshore. Like many productive fossil-producing sites it is an erosional cliff, prone to rockfalls, which periodically remove sections of the cliff exposing fresh fossils. The fossil beds around Lyme Regis are internationally famous, due to the large Marine Reptile fossils collected their by Mary Anning in the early nineteenth century, and John Fowl's novel The French Lieutenant's Woman, which was set in the area and had a palaeontologist as its male lead.

Tourists inspecting Ammonites on the Limestone Pavement at Monmouth Beach. Discovering Fossils.

This summer has seen exceptional rainfall in Dorset, which can prove hazardous at bedded limestone cliffs such as Monmouth Beach. On 23 June this year 22-year-old Charlotte Blackmam from Nottinghamshire was killed by a rockfall at nearby Burton Bradstock, which is geologically similar to the West Cliffs at Lyme. The problems occur on cliffs made up of alternate layers of limestone and mudstone. In heavy rains water washes the mudstone layers out at the cliff-face, leaving the limestone layers unsupported. Eventually insufficient mudstone remains to support the cliff surface, and the limestone layers collapse, leaving a new cliff-face in which the two layers are more-or-less flush.

The West Cliffs at Lyme Regis, showing the same bedded limestone structure as that which caused a fatal rock-fall at nearby Burton Bradstock in June 2013. Discovering Fossils.

After careful consideration of the condition of the cliffs at Monmouth Beach, which suffered two rockfalls in July and which still appear at risk of further, possibly larger, collapses, Dorset County Council and Natural England (who own the cliffs), have decided to close the beach. It is unclear how long the closure will remain in place, though it will probably last until after English schools reopen in September, when tourism at Lyme Regis drops off abruptly. If the closure lasts longer then it could cause problems for a number of English universities, which tend to run undergraduate field-trips to Lyme early in the academic year.

See also Woman killed by rockfall on Dorset Beach, Section of White Cliffs of Dover collapses into the sea,  A Pterosaur from the Jurassic of Dorset, England, A review of Jurassic Tyrannosauriods leads to the description of a new genus and The Weymouth Pliosaur.

Follow Sciency Thoughts on Facebook.