''Principiala'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

lacewing The Hemerobiiformia are a suborder of insects in the order Neuroptera that include most of the lacewings, antlions and their allies. The phylogeny of the Neuroptera was explored in 2014 using mitochondrial DNA sequences. The results indicate t ...

in the moth lacewings family

Ithonidae Ithonidae, commonly called moth lacewings and giant lacewings, is a small family (biology), family of Pterygota, winged insects of the insect order (biology), order Neuroptera. The family contains a total of ten living genera, and over a dozen e ...

. The genus is known from

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

fossils found in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

, and possibly

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

. The genus is composed of two species, the type species ''Principiala incerta'', and ''Principiala rudgwickensis''.

History and classification

''Principiala'' is known only from three fossils assigned to the two species and an additional fossil tentatively assigned to the genus. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

adult of ''P. incerta'', specimen number SMNK PAL 5352 is housed in the collections of the

State Museum of Natural History Stuttgart The State Museum of Natural History Stuttgart (), abbreviated SMNS, is one of the two state of Baden-Württemberg's natural history museums. Together with the State Museum of Natural History Karlsruhe (Staatliches Museum für Naturkunde Karls ...

, while the partial

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...

adult, specimen number SMNS 66000/255, is part of the

State Museum of Natural History Karlsruhe The State Museum of Natural History Karlsruhe (), abbreviated SMNK, is one of the two state of Baden-Württemberg's natural history museums. Together with the State Museum of Natural History Stuttgart (Staatliches Museum für Naturkunde Stuttgar ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

. The specimens are preserved as

compression fossil A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression fossils, it is very common to find plants preserved this way. The reason f ...

s in finely laminated

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

s, which were recovered from outcrops of the Nova Olinda Member of the Late Aptian

Crato Formation The Crato Formation is a geologic formation (stratigraphy), formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätten, Lagerstätte (undisturbed fossil accumulation) for palaeontology, pa ...

in Northeastern

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. ''P. rudgwickensis'' was described from a single part and counterpart holotype, "BMB 025005, -6" that is part of the

Booth Museum of Natural History Booth Museum of Natural History is a charitable trust-managed, municipally-owned museum of natural history in the city of Brighton and Hove in the South East of England. Its focus is on Victorian taxidermy, especially of British birds, as well ...

Brighton and Hove Brighton and Hove ( ) is a City status in the United Kingdom, city and unitary authority area, ceremonially in East Sussex, England. There are multiple villages alongside the seaside resorts of Brighton and Hove in the district. It is administe ...

, England. The species is older than ''P. incerta'', having been recovered from Rudgwick Brickworks which mined sediments of the

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a ...

Upper Weald Clay Formation. A single wing has been recovered from the

Yixian Formation The Yixian Formation (; formerly Romanization of Chinese, transcribed as Yihsien Formation or Yixiang Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the Barremian stage of the Early Cretaceous. I ...

in China which was noted as probably belonging to the genus by Makarkin ''et al'' in 2012. The Brazilian fossils were first studied by the paleoentomologists Vladimir N. Makarkin of the Far Eastern Branch of the Russian Academy of Sciences and Federica Menon from the

University of Manchester The University of Manchester is a public university, public research university in Manchester, England. The main campus is south of Manchester city centre, Manchester City Centre on Wilmslow Road, Oxford Road. The University of Manchester is c ...

in England. Their 2007

type description A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it differ ...

of the new genus and species was published in the journal ''

Cretaceous Research ''Cretaceous Research'' is a bimonthly peer-reviewed scientific journal published by Elsevier. The journal focuses on topics dealing with the Cretaceous period and the Cretaceous–Paleogene boundary. Abstracting and indexing The journal is abst ...

''. The genus name ''Principiala'' was coined by the researchers as a combination of "Principi", in honor of Italian entomologist Maria Principi and the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word ''ala'' meaning "wing". The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

"incerta" is derived from the Latin ''incertus'', in reference to the uncertain relationship of the genus within Ithonidae. Two years later a group of researchers led by paleoentomologist James Jepson described the second species ''P. rudgwickensis''. The team chose the species name "rudgwickensis" as a reference to the Rudgwick Brickworks where the fossil was found. Overall the vein structure of ''Principiala'' is most similar to the genus '' Allorapisma'', known from

Ypresian In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

fossils found in the northwestern United States. The wings of both genera show the apical end of the Rs vein fused to the MA vein. Both have similar positioning and shaping of the MP vein and the CuA vein running parallel to the MP vein. As such, Makarkin and Archibald suggested the two be grouped in an informal suprageneric group called the ''Principiala'' group. This group is one of three possibly monophyletic groups in Ithonidae, the others two being the ''Ithone'' group and the ''Rapisma'' group.

Description

The genus is identified by the short length of the antennae. Being approximately long, they are the shortest of the described neuropterans, with ''Rapisma'' having the shortest of the extant genera. The costal region of the fore-wing shows a regular series of cross-veins which gives the appearance of a longitudinal vein in the base area of the region. In contrast to the cross-veins of the costal area, the cross-veins in the subcostal area of the fore-wing are there are irregularly spaced and uneven. The area between the radius and median veins is notably narrow near the fore-wing base, and narrows towards the wing tip until the two veins merge. As with many Ithonidea genera, the head is pulled most of the way under the pronotal shield. ''P. incerta'' and ''P. rudgwickensis'' are distinguished by the characters of the species fore-wings, with an approximate length of for the former and only an estimated in the latter. In addition the last branch of the Rs vein in ''P. rudgwickensis'' is distinctly longer than that seen in ''P. incerta'' before the branches merge with the Median vein. ''P. rudgwickensis'' also shows a number of crossveins between the Rs branches of the Radial vein and the tip sections of the Rs branches are straight, both features absent or not preserved in ''P. incerta''.

References

{{Taxonbar, from=Q7553270 Ithonidae Early Cretaceous insects Insects of South America Early Cretaceous animals of South America Crato Formation Cretaceous insects of Europe Cretaceous insects of Asia Fossil taxa described in 2007 Fossil taxa described in 2009 Early Cretaceous arthropods of Europe Early Cretaceous arthropods of Asia Prehistoric insect genera Neuroptera genera