Nesiotites

Nesiotites is an extinct genus of large red-toothed shrews belonging to the tribe Nectogalini known from the latest Miocene/Early Pliocene to Holocene of the Balearic Islands of Mallorca and Menorca.

Nesiotites Temporal range: Early Pliocene–Holocene PreꞒ Ꞓ O S D C P T J K Pg N
Size comparison of the Balearic shrew Nesiotites hidalgo (top) with a water shrew (Neomys, below)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Eulipotyphla
Family:	Soricidae
Tribe:	Nectogalini
Genus:	†Nesiotites Bate, 1945
Species
†N. hidalgo Bate, 1945 (type) †N. meloussae Pons and Moyà, 1980 †N. ponsi Reumer, 1979 †N. rafelinensis? Rofes et al, 2012

Taxonomy

Nesiotites was originally described by Dorothea Bate in 1945, with the type species being Nesiotites hidalgo.^[1] Originally, two species from the islands of Corsica and Sardinia (N. corsicanus and N. similis) were included in the genus, but these are now rejected from the genus, and Nesiotites is now generally used exclusively for the Balearic species, as otherwise the genus would likely be polyphyletic.^[2]

The genus includes the chronospecies N. rafelinensis (earliest Pliocene)^[3] (the validity of this species disputed, as some authors contend that it is not morphologically distinct from N. ponsi^[4][5]) N. ponsi (Late Pliocene), N. meloussae/N. aff. ponsi (Early Pleistocene) and N. hidalgo (Middle Pleistocene-Holocene). These are largely distinguished by differences in body size and characters of the teeth.^[3][6]

Based on a mitochondrial genome from Nesiotites hidalgo, their closest living relative is the terrestrial Himalayan shrew (Soriculus), and related to other terrestrial nectogaline shrews known from Asia (Episoriculus and Chodsigoa), rather than to the nectogaline water shrews (Chimarrogale, Nectogale and Neomys). A molecular clock analysis suggests that Himalayan shrews and Balearic shrews genetically diverged approximately 6.44 million years ago. Based on morphological data, it is thought that Nesiotites is closely related and likely descended from the extinct genus Asoriculus, known from the Late Miocene-Holocene of Europe and North Africa, which now includes the Corsican and Sardinian species formerly included in Nesiotites.^[2]

Position of Nesiotites within Nectogalini based on DNA and morphological characters after Bover et al (2018):^[2]

Nectogalini	Episoriculus fumidus Chimarrogale himalayica (Himalayan water shrew) Nectogale elegans (elegant water shrew) Neomys Neomys fodiens (water shrew) †Neomys newtoni Soriculus nigrescens (Himalayan shrew) †Nesiotites hidalgo †Asoriculus gibberodon Episoriculus Episoriculus leucops Episoriculus caudatus Episoriculus macrurus Chodsigoa Chodsigoa parca Chodsigoa sodalis Chodsigoa hypsibia

Description

Members of Nesiotites exhibited a large body size compared to their likely mainland ancestor, Asoriculus gibberodon (estimated to weigh 8.85 grams (0.312 oz)), as well to most other members of Nectogalini, an example of island gigantism. The species of the genus showed an increase in body size over time, with the estimated weight of N. ponsi being 14.58 grams (0.514 oz) while the last species, N. hildalgo being estimated at 26.63–29.31 grams (0.939–1.034 oz), being exceeded in size amongst Nectogalini only by Asiatic water shrews (Chimarrogale).^[7]

Evolutionary history

Nesiotites originally colonised Mallorca during the Messinian stage of the Late Miocene, when during the Messinian salinity crisis (5.96–5.33 million years ago) the Mediterranean sea evaporated allowing animals from the Iberian Peninsula to disperse to the Balearics. Later becoming isolated on the island when the Mediterranean refilled as result of the Zanclean Flood around 5.3 million years ago, at the beginning of the Pliocene. Nesiotites later spread to Menorca during the Pliocene-Pleistocene transition, when episodes of low sea level connected the two islands.^[8][6] During most of its existence, it represented only one of three terrestrial mammal lineages native to the Balearic islands, alongside the giant dormouse Hypnomys and the dwarf goat-antelope Myotragus. The last Nesiotites chronospecies, N. hidalgo, became extinct shortly after human settlement of the Balearics, which occurred sometime prior to 2282 BC, with the youngest radiocarbon date for the species dating to approximately 3027 BC.^[9]

References

1. Bate, Dorothea M.A. (November 1944). "LXIII.— Pleistocene shrews from the larger Western Mediterranean Islands". Annals and Magazine of Natural History. 11 (83): 738–769. doi:10.1080/00222934408527471. ISSN 0374-5481.
2. Bover, Pere; Mitchell, Kieren J.; Llamas, Bastien; Rofes, Juan; Thomson, Vicki A.; Cuenca-Bescós, Gloria; Alcover, Josep A.; Cooper, Alan; Pons, Joan (August 2018). "Molecular phylogenetics supports the origin of an endemic Balearic shrew lineage (Nesiotites) coincident with the Messinian Salinity Crisis". Molecular Phylogenetics and Evolution. 125: 188–195. doi:10.1016/j.ympev.2018.03.028. PMID 29608962. S2CID 5010906.
3. Rofes, J.; Bover, P.; Cuenca-Bescós, G.; Alcover, J.A. (2012). "Nesiotites rafelinensis sp. nov., the earliest shrew (Mammalia, Soricidae) from the Balearic Islands, Spain". Palaeontologia Electronica. 15 (1): 8A. doi:10.26879/282.
4. Rofes, J; Bover, P; Cuenca-Bescós, G; Alcover, Ja (2013). "Proportions, characters and chronologies: their contribution to systematic paleontology. A rebuttal to Furió and Pons-Monjo". Palaeontologia Electronica. doi:10.26879/412. ISSN 1094-8074.
5. Furió, M; Pons-Monjo, G (2013). "The use of the species concept in paleontology. Comment on "Nesiotites rafelinensis sp. nov., the earliest shrew (Mammalia, Soricidae) from the Balearic Islands, Spain" by Rofes et al., 2012". Palaeontologia Electronica. doi:10.26879/336. ISSN 1094-8074.
6. Cardona, Josep Quintana; Agusti, Jordi (May 2019). "First evidence of faunal succession in terrestrial vertebrates of the Plio-Pleistocene of the Balearic Islands, western Mediterranean". Comptes Rendus Palevol. 18 (3): 317–324. doi:10.1016/j.crpv.2019.02.001. S2CID 150158569.
7. Moncunill-Sole, B.; Jordana, X.; Köhler, M. (2016). "How common is gigantism in insular fossil shrews? Examining the 'Island Rule' in soricids (Mammalia: Soricomorpha) from Mediterranean Islands using new body mass estimation models". Zoological Journal of the Linnean Society. 178 (1): 163–182. doi:10.1111/zoj.12399.
8. Pons-Monjo, Guillem; Moyà-Solà, Salvador; Furió, Marc (July 2012). "New data on the origin of Nesiotites (Soricidae, Mammalia) in Menorca (Balearic Islands, Spain)". Comptes Rendus Palevol. 11 (5): 393–401. doi:10.1016/j.crpv.2012.03.001.
9. Valenzuela, Alejandro; Torres-Roig, Enric; Zoboli, Daniel; Pillola, Gian Luigi; Alcover, Josep Antoni (2021-11-29). "Asynchronous ecological upheavals on the Western Mediterranean islands: New insights on the extinction of their autochthonous small mammals". The Holocene. 32 (3): 137–146. doi:10.1177/09596836211060491. ISSN 0959-6836. S2CID 244763779.