Saturday, March 4, 2023

[Arachnida • 2023] Bothriurus mistral • the Highest-dwelling Bothriurus (Scorpiones: Bothriuridae) from the western Andes

Bothriurus mistral
Ojanguren-Affilastro, Benítez, Iuri, Mattoni, Alfaro & Pizarro-Araya, 2023

We describe Bothriurus mistral n. sp. (Scorpiones, Bothriuridae) from the Chilean north-central Andes of the Coquimbo Region. This is the highest elevational discovery for Bothriurus in the western slopes of the Andes. This species was collected in the Estero Derecho Private Protected Area and Natural Sanctuary as part of the First National Biodiversity Inventory of Chile of the Integrated System for Monitoring and Evaluation of Native Forest Ecosystems (SIMEF). Bothriurus mistral n. sp. is closely related to Bothriurus coriaceus Pocock, 1893, from the lowlands of central Chile. This integrative research includes a combination of traditional morphometrics and geometric morphometric analyses to support the taxonomic delimitation of the species.

 Living specimens and type locality of Bothriurus mistral n. sp.
 (A) Living specimen (B) Living specimen under UV light.
(C) Type locality in the Estero Derecho Private Protected Area and Natural Sanctuary (Coquimbo Region, Chile). (D) Aerial view of the type locality.

 Bothriurus mistral n. sp., habitus.
(A) Male, dorsal aspect, (B) Male, ventral aspect, (C) Female, dorsal aspect, (D) Female, ventral aspect.
Scale bars: 10 mm.

Bothriurus mistral n. sp. Ojanguren-Affilastro, Mattoni, Alfaro & Pizarro-Araya

Diagnosis and comparisons: Bothriurus mistral n. sp. is most closely related to B. coriaceus, which occurs in neighboring areas but at much lower altitudes. Both species can be easily told apart by their pigment pattern and morphology. Bothriurus mistral n. sp. is more pigmented than B. coriaceus; the pigment pattern of tergites I–VI is usually restricted to the anterior third of the segment in B. coriaceus (Fig 8C), whereas in B. mistral n. sp. it occupies more than the anterior half of each segment (Fig 8D). Additionally, B. coriaceus only has a median wide stripe in the ventral surface of metasomal segments I–IV (Fig 8A), whereas B. mistral n. sp. has three ventral stripes, two VL and a VM (Fig 8B). Bothriurus coriaceus has more developed ventral carinae in metasomal segment I (Fig 6G–6J). Metasomal segment V is more elongated in B. mistral n. sp. males (Fig 6E), and its length/width ratio ranges from 1.80 to 2.01 (N = 10; mean = 1.86), whereas in B. coriaceus males (Fig 6F) it ranges from 1.61 to 1.76 (N = 10; mean = 1.67). The base of the aculeus in B. mistral n. sp. males is slightly thicker and higher than in B. coriaceus males (Fig 6B and 6D), but this character is highly variable. There are also some conspicuous differences in the hemispermatophores of both species; in B. mistral n. sp. the distal lamina is more elongated and more recurved apically than in B. coriaceus (Fig 7A and 7B), being the distal lamina proportionally shorter and wider in B. coriaceus than in B. mistral n. sp. considering the total length of the hemispermatophore. Hemispermatophore total length/distal lamina length ratio ranges from 1.88 to 1.98 (N = 5; Mean = 1.93) in B. mistral n. sp., whereas in B. coriaceus it ranges from 2.04 to 2.08 (N = 5; Mean = 2.06). Hemispermatophore total length/distal lamina width ratio ranges from 7.71 to 8.23 (N = 5; Mean = 8.03) in B. mistral n. sp., whereas in in B. coriaceus it ranges from 6.31 to 7.16 (N = 5; Mean = 6.81).

Etymology: The specific name mistral is a noun in apposition referring to Gabriela Mistral, pseudonym of the Chilean poetess Lucila María Godoy Alcayaga (1889–1957), who was born in Vicuña and raised in Monte Grande, both in the Elqui valley (Coquimbo Region), an area adjacent to the type locality of this species. For her poetry work, she was awarded the Nobel Prize in Literature in 1945 and was the first Ibero-American woman and the second Latin American person to receive the Nobel Prize. Gabriela Mistral worked as a teacher at numerous schools of the Elqui valley and became a leading thinker as to the role of public education. She was also involved in the reformation of the Mexican education system, and since the 1920s, led an itinerant life due to her work as a consul and representative for international organizations in the Americas and Europe.

Distribution: Bothriurus mistral n. sp. is only known from its type locality, the Estero Derecho Private Protected Area and Natural Sanctuary (30°23ʹ3.86ʺS, 70°24ʹ44.97ʺW, 3,034 masl), located in the Paihuano mountain range, an area with a surface of 31,680 ha, placed at high altitudes of the north central Chilean Andes (Coquimbo Region, Chile) (Fig 1).

The area where Bothriurus mistral n. sp. was collected occupies the sub-Andean floor, which is characterized by the presence of medium-height shrub vegetation and scrublands, with the dominant species Stipa chrysophylla E. Desvaux, 1854, Viviana marifolia Cavanilles, 1804, Cristaria andicola Gay, 1846, Adesmia hystrix Philippi, 1860 (Fabaceae), and Ephedra americana Humb. & Bonpl. ex Willd 1806; and the lowermost Andean floor, characterized by a low tropical-Mediterranean shrubland of Adesmia subterranea Clos, Gay, C., 1838, and Adesmia echinus C. Presl, 1791 (Fabaceae) [15, 31].

Bothriurus mistral n. sp. has been found in sympatry with Brachistosternus gayi Ojanguren-Affilastro, Pizarro-Araya & Ochoa, 2018, and with an undetermined, possibly new, species of Brachistosternus.

Andrés A. Ojanguren-Affilastro, Hugo A. Benítez, Hernán A. Iuri, Camilo I. Mattoni, Fermín M. Alfaro and Jaime Pizarro-Araya. 2023. Description of Bothriurus mistral n. sp., the Highest-dwelling Bothriurus from the western Andes (Scorpiones, Bothriuridae), using Multiple Morphometric Approaches. PLoS ONE. 18(2): e0281336. DOI: 10.1371/journal.pone.0281336