Agulla mineralensis is an extinct species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of snakefly

Snakefly

Snakeflies are a group of insects in the order Raphidioptera, consisting of about 210 extant species. Together with the Megaloptera they were formerly placed within the Neuroptera, but now these two are generally regarded as separate orders....

 in the raphidiid genus Agulla

Agulla (snakefly)

Agulla is a genus of modern snakeflies in the family Raphidiidae.Agulla species are predatory, both as adults and larvae. In North America occur exclusively in the Western United States, namely in the Rocky Mountains and westward, including the southwestern deserts.-Systematics:At present 31 living...

. The species is solely known from the Middle Miocene

Middle Miocene

The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene....

, late Bartovian stage

Barstovian

The Barstovian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 16,300,000 to 13,600,000 years BP, a period of . It is usually considered to overlap the Langhian and Serravallian...

, Pacific Union Site in the Stewart Valley Group, Mineral County, Nevada.

History and classification

Agulla mineralensis is known only from one fossil, the holotype

Holotype

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

, specimen number 539. The specimen is composed of a complete specimen of an isolated hind-wing

Insect wing

Insects are the only group of invertebrates known to have evolved flight. Insects possess some remarkable flight characteristics and abilities, still far superior to attempts by humans to replicate their capabilities. Even our understanding of the aerodynamics of flexible, flapping wings and how...

 which is preserved as a compression fossil

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...

 in sedimentary paper shale. The fossil was recovered from outcrops of the Stewart Valley group shales at the Pacific Union site, BLM locality #26-30-09-335, in Mineral County, Nevada

Mineral County, Nevada

Mineral County is a county located in the U.S. state of Nevada. As of the 2000 census, the population was 5,071. In 2009, it was estimated to have dropped to 4,662. Its county seat is Hawthorne.-History:...

, USA. A. mineralensis was first studied by Michael S. Engel

Michael S. Engel

Michael S. Engel is an American paleontologist and entomologist. He has undertaken field work in Central Asia, Asia Minor, and the Western Hemisphere, and published more than 300 papers in scientific journals. He was trained at the University of Kansas where in 1993 he received a B.S. in Cellular...

 of the University of Kansas

University of Kansas

The University of Kansas is a public research university and the largest university in the state of Kansas. KU campuses are located in Lawrence, Wichita, Overland Park, and Kansas City, Kansas with the main campus being located in Lawrence on Mount Oread, the highest point in Lawrence. The...

, Lawrence, Kansas

Lawrence, Kansas

Lawrence is the sixth largest city in the U.S. State of Kansas and the county seat of Douglas County. Located in northeastern Kansas, Lawrence is the anchor city of the Lawrence, Kansas, Metropolitan Statistical Area, which encompasses all of Douglas County...

, USA. His 2009 type description of the new species was published in the journal Transactions of the Kansas Academy of Science

Transactions of the Kansas Academy of Science

Transactions of the Kansas Academy of Science is a biannual peer-reviewed academic journal published by the Kansas Academy of Science. The journal covers biological and physical sciences, mathematics and computer science, history, culture, and philosophy of science, and science education....

. Engel coined the specific epithet mineralensis in honor of Mineral County

Mineral County, Nevada

Mineral County is a county located in the U.S. state of Nevada. As of the 2000 census, the population was 5,071. In 2009, it was estimated to have dropped to 4,662. Its county seat is Hawthorne.-History:...

, where the species was found. At the time of the species description, Agulla mineralensis was the only member of the order Raphidioptera to be found in Neogene

Neogene

The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...

 aged fossil deposits in North America.

Description

The lone specimen of Agulla mineralensis is approximately 10.9 millimetre (0.429133858267717 in) in length and a maximum of 3.8 millimetre (0.149606299212598 in) in width. The presence of distinct M and Cu veins in the very basal section of the wing denotes the wing is a hind-wing. The wing is apparently hyaline

Hyaline

The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...

 in coloration

Animal colouration

Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. The mechanisms for colour production in animals include pigments, chromatophores, structural coloration, and bioluminescence....

 with a slight darkening of the pterostigma

Pterostigma

The pterostigma is a cell in the outer wing of insects which is often thickened or coloured and so stands out from other cells. It is particularly noticeable in dragonflies, but present also in other insect groups, such as snakeflies, hymenopterans and megalopterans.The purpose of the pterostigma,...

 area. The subcostal space is about half the width of the preserved section of the costal space. The notably long M vein prior to separation into MP and MA veins in A. mineralensis distinguishes the species from other Tertiary raphidiids with described hind-wings. While the elongated pterostigma is similar to the extinct species Raphidia mortua and Raphidia funerata

Raphidia funerata

Raphidia funerata is an extinct species of snakefly in the Raphidiidae genus Raphidia. The name R. funerata is derived from the Latin funeratus meaning to "bury" or "intern". The species is known from a single female specimen, the holotype, deposited in the Department of Palaeontology at the...

, the M vein length and less branching of the veins near the wing tip separate them from A. mineralensis.