page_title: Nanahughmilleria
section_title: Creation of the subgenus and further discoveries
hierarchical_section_title: Nanahughmilleria / History of research / Creation of the subgenus and further discoveries
caption_attribution_description: English: Fossils of Nanahughmilleria clarkei .
context_page_description: Nanahughmilleria is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Nanahughmilleria have been discovered in deposits of Devonian and Silurian age in the United States, Norway, Russia, England and Scotland, and have been referred to several different species.
  Nanahughmilleria is classified in the family Adelophthalmidae, the only clade in the superfamily Adelophthalmoidea. This clade was characterised by their small size, their parabolic carapaces and the presence of epimera on the seventh segment, among others. Nanahughmilleria was different from its relatives by the presence of more spines in its appendages and by its genital morphology. The largest species confidently assigned to the genus was N. norvegica at 10 cm, making it a comparatively small eurypterid.
context_section_description: In 1961, Kjellesvig-Waering separated Hughmilleria into two subgenera according to the morphology of the eyes, H. (Hughmilleria) for species with large ovoid marginal eyes and H. (Nanahughmilleria) for species with small reniform intramarginal eyes. For the latter one, H. (N.) norvegica was designated as subgenotype. He assigned a total of seven species to the subgenus, of which only four (two of them tentatively) are still in Nanahughmilleria. The generic name is composed by the Latin word nana ("dwarf") and Hughmilleria.
  N. clarkei is based on a series of fossils described and assigned to Hughmilleria shawangunk by John Mason Clarke and Rudolf Ruedemann in 1912. They believed that the carapaces with intramarginal eyes were modified by the compression. While this could happen in a single specimen, it is impossible to be in so many. Kjellesvig-Waering realized this and erected the species N. clarkei in 1964, named after Clarke, who described the original Shawangunk eurypterid fauna. This small species of only 4 cm (1.6 in) had a lanceolate carapace with intramarginal eyes located anteriorly. The telson was broad and lanceolate. This species is characterized by the presence of spurs in the genal angles (a "flat" part of the carapace edge).
  It would not be until 2012 when another new species, N. notosibirica, was described by Shpinev. This species is known from two specimens, the holotype (PIN 1139/1) and paratype (PIN 1139/2). Its specific name, notosibirica, comes from the Greek word notos (southern) and Siberia, referring to the place where it was discovered. The carapace was parabolic and surrounded by a narrow marginal rim and with elongated eyes probably reniform. Only the fourth and fifth pair of prosomal appendages is known. These were of Hughmilleria-type and with rather small spines. The telson was small and wedge-shaped, known from fragmentary remains. The metasoma (the posterior "part" of the body) was notably narrower than the mesosoma (the "median part"). The total size of the species could be of 9 cm (3.5 in), being one of the largest species of Nanahughmilleria. This species differs from the others in the proportions of the body and position of the eyes.
  In addition, the species N. lanceolata is tentatively classified as part of Nanahughmilleria. This species was originally described by Salter in 1856 as another species of his new genus Himantopterus. The swimming legs of this species were long and narrow, reaching the sixth segment of the body. The telson was lanceolate and with a keel in the middle. All known specimens of N. lanceolata lacks of eyes, making it difficult to determine their phylogenetic position. However, the prosomal and genital appendages were not typical of the Adelophthalmoidea, but probably of the Eurypteroidea.
caption: Fossils of N. clarkei previously assigned to Hughmilleria shawangunk.
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