Hylomys parvus Robinson and Kloss, 1916

Hinckley, Arlo, Camacho-Sanchez, Miguel, Chua, Marcus A H, Ruedi, Manuel, Lunde, Darrin, Maldonado, Jesús E, Omar, Hasmahzaiti, Leonard, Jennifer A & Hawkins, Melissa T R, 2024, An integrative taxonomic revision of lesser gymnures (Eulipotyphla: Hylomys) reveals five new species and emerging patterns of local endemism in Tropical East Asia, Zoological Journal of the Linnean Society 202 (2), pp. 1-33 : 22-23

Hylomys parvus Robinson and Kloss, 1916

Hylomys parvus Robinson and Kloss, 1916: 269 . Original description.

Holotype: NHMUK 1919.11.5.12 , an adult female (skin and skull) collected by H.C. Robinson and C.B. Kloss on 9 May 1914. Head and body length 105 mm, 25 tail mm (23.8% HB), hindfoot 23.5 mm, ear length (na), weight (na). Skull measurements in the Supporting Information, Table S2.

Type locality: Korinchi Peak , 10 000 ft (= Gunung Kerinci, 3048 m), West Sumatra, Indonesia.

Paratypes (19): Original description specifies that 20 specimens were examined but does not cite these. These are the specimens we could locate from the type series: NHMUK ZD 1919.11.5.10 , RMNH23892 , ZRC4.3427 , ZRC4.3430 , ZRC4.3431 , ZRC4.3432 , ZRC4.3434 , and ZRC4.3935 .

Emended diagnosis: A small-sized Hylomys (average HB = 107 mm, GLS = 30.9 mm) characterized by thick and entirely soft fur, a very longandbicolouredblacktail(averageT = 23 mm; T / HB = 22.4%), and long ears (average E = 19 mm, E/ GLS = 56.3%), supraorbital process absent, dentition is gracile, notch between premaxilla tips is acute-angled, frontal bone and dorsal region of maxillary are smooth, occipital crest minute, P4 cingulum and parastyle absent or inconspicuous, p3 with two non-fused roots.

Comparisons: Comparisons with Sumatran H. maxi and H. vorax are detailed in these species accounts. It can be distinguished from all relatives by its smaller mandible ( LMA <22.2 mm vs. LMA> 22.4 mm), and by having two non-fused roots in p3 ( Jenkins and Robinson 2002).

Distribution, habitat, and natural history: Sumatran endemic, currently known from montane forest between 2200 and 3330 m a.s.l. on Mount Kerinci ( Ruedi et al. 1994). This species has been recorded in sympatry with H. maxi at 2225 m by Robinson and Kloss (1918). It shares habitat with Crocidura beccari , C. lepidura , C. aequicauda , Maxomys hylomyoides , Mus crociduroides, Niviventer fraternus , Rattus korinchi , and Sundasciurus altitudinis ( Robinson and Kloss 1918) . Hylomys parvus might limit the upper distribution of Crocidura lepidura according to Ruedi (1995).

Conservation: Recorded in Kerinci Seblat National Park ( KSNP). Although the habitat of H. parvus is protected, deforestation is ongoing, since KSNP has lost c. 38 000 ha of its primary forest from 2012 to 2017 ( Dwiyahreni et al. 2021). In addition, 12 current road proposals across Kerinci Seblat National Park are being evaluated by the Indonesian Government, which would contribute to extensive habitat fragmentation if approved ( Sloan et al. 2019). It is anticipated that the Trans-Sumatra Highway’s completion, if constructed according to the current plan, would also encourage increased anthropogenic pressure on the outskirts of the KSNP, potentially impacting its fragile ecosystem ( Sloan et al. 2019). This species was listed as critically endangered in 1996. However, in 2008, it was reclassified as vulnerable, a status that remains current on the IUCN Red List. This conservation status change seems unjustified since it is based on a miscitation of Ruedi et al. (1994) and overestimation of the extent of occurrence of H. parvus . The species was just recorded on Mt. Kerinci in Ruedi et al. (1994), not north and south of it, which reduces considerably its extent of occurrence. Habitat availability and quality has probably decreased from 1996 to 2023 due to climate change. Further research is needed to determine population trends of H. parvus , evaluate if its distribution spans additional mountains besides Mt. Kerinci, and whether H. maxi is outcompeting and displacing H. parvus due to climate change-driven elevational shifts ( Ruedi et al. 1994).