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| Brachistosternus pehuenche Ojanguren-Affilastro, Alfaro, Iuri, Camousseigt-Montolivo & Pizarro-Araya, 2025 . |
Abstract
Brachistosternus pehuenche sp. nov. (Scorpiones, Bothriuridae) is described from the Mauline Andean forests of the northern Chilean Patagonia, located within the upper basin of the Maule Valley. Its unique geography and the discovery of this partial isolation, as a result of the surrounding higher altitudes, support the role of this valley as a biodiversity hotspot, fostering a variety of endemic epigean arthropods. The discovery of this third endemic scorpion species highlights the area’s ecological uniqueness. The species is most similar to Brachistosternus negrei, a species found in the southern Chilean forests, but distinct morphological traits, such as pigmentation patterns and metasomal structures, clearly separate the two. This study underscores the ecological value of the Maule Valley, which, despite its high endemism, remains unprotected and is subject to significant anthropogenic pressures, including agriculture, hydropower projects, and international transit routes. The need for conservation initiatives in this region is critical to preserve its exceptional biodiversity. This work not only adds to the taxonomy of Brachistosternus but also raises fundamental questions about the processes driving endemism in the Andes and the broader implications for the conservation of montane ecosystems.
Key Words: Area of endemism, Bothriuridae, Chile, Mauline woods, new species, Scorpiones
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| Brachistosternus pehuenche sp. nov., habitus. A. Male, dorsal aspect; B. Male, ventral aspect; C. Female, dorsal aspect; D. Female, ventral aspect. Scale bar: 1 cm. |
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Brachistosternus pehuenche sp. nov. (Scorpiones; Bothriuridae). A. Preying on an adult of Athlia rustica (Coleoptera: Scarabaeidae); B. Climbing on branches of Lobelia sp. (Campanulaceae) in a hunting position for flying insects; C. Male, living specimen. |
Brachistosternus pehuenche sp. nov.
Diagnosis: Brachistosternus pehuenche sp. nov. is most similar to B. negrei, which is the only Brachistosternus species occurring in nearby areas of the south-central Chilean woods. Both species can be easily distinguished by several morphological characters. Brachistosternus pehuenche, on one hand, has tergites that bear two lateral spots, with pigment occupying most of the posterior lateral margins and leaving a median unpigmented stripe (Figs 4A, C, 5A); B. negrei, on the other hand, has five spots on each segment, one antero-median, two lateral, and two postero-submedian, in some cases connected by faint reticulate pigment (Fig. 5E). The metasomal segments I–IV of B. pehuenche bear two VL narrow stripes and a VM wide stripe (the VM stripe can be very faint or absent in segments I–III) (Fig. 5B), whereas in B. negrei there are two VL stripes and two VSM stripes (VSM stripes can be faint or absent in segments I–III) (Fig. 5F). The paired dorsal glands of metasomal segment V of males, or Androvestigia, are medium-sized in B. pehuenche, occupying from a third to almost the entire posterior half of the segment (Fig. 5C), whereas in B. negrei these glands are small, occupying between 10 to 25 percent of the dorsal surface of the segment (Fig. 5G). Metasomal segment V is more granular ventrally in B. pehuenche than in B. negrei, with some granules even forming a slight ventro-median carinae in the former (Fig. 5D), whereas in B. negrei there is no VM carina at all, and ventral granules are more sparse and smaller (Fig. 5H).
Etymology: The specific epithet “pehuenche” is a noun in apposition referring to the Pehuenche International Pass between Argentina and Chile, in the northern Patagonia, where this and other endemic scorpion species have been collected. Pehuenche is also the name of the indigenous people of this area, belonging to the Mapuche cultural group.
Andrés A. Ojanguren-Affilastro, Fermín M. Alfaro, Hernán A. Iuri, Bernardino Camousseigt-Montolivo and Jaime Pizarro-Araya. 2025. Description of Brachistosternus pehuenche sp. nov. (Scorpiones, Bothriuridae), A New scorpion Species from the upper Maule Valley, in the southern Chilean Andes. Zoosystematics and Evolution. 101(3): 969-981. DOI: doi.org/10.3897/zse.101.146451