Hylomys dorsalis Ŋomas, 1888,

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 intbgoativb taxonomic obvision of lbssbo gvmnuobs (Eulipotvphla: Hylomys) obvbals fivb nbw spbcibs and bmboging paưbons of local bndbmism in Toopical East Asia, Zoological Journal of the Linnean Society 202 (2), pp. 1-33 : 24-26

Hylomys dorsalis Ŋomas, 1888 stat. nov.

Hylomys suillus dorsalis Thomas, 1888: 407 . Original description.

Hylomys suillus dorsalis Thomas, 1889: 229 .

Holotype: Not specified in original description. NHMUK 1895.10.4.2 , adult male (skin and damaged skull), collected by John Whitehead in February 1888 was possibly designated as a lectotype by Thomas (1889). However, its field and museum number was not provided, just the date of collection and elevation, but this seemed to be enough to identify it by NHMUK staff. We thus clarify here that NHMUK 1895.10.4.2 should be treated as the lectotype of this species . Head and body length 116 mm, 16 tail mm (13.8% HB), hindfoot 25 mm, ear length (na), weight (na). Skull measurements in the Supporting Information, Table S 2.

Type locality: ‘Mount Kina Balu, North Borneo’ (= Gunung Kinabalu , Sabah, Borneo, Malaysia; lectotype was collected at 2438 m a.s.l.).

Paratypes: Non-existent.

Emended diagnosis: A large-sized Hylomys (average HB = 135 mm, W = 61 g) characterized by a black dorsal stripe in adults, at least in the nape-shoulder area, which can sometimes be relatively inconspicuous. Dorsum and flank pelage coloration are homogenous. Adults have a ventral brown-grey coloration (at least from late April to late August). Forefoot with long nails. Hindfoot is large (average HF = 25.7 mm, HF + nail = 27.7 mm). Skull is characterized by a unique combination of long nasals (average NL = 14 mm) that generally extend to the level of the antorbital rim, broad interorbital constriction (average IOB = 9.5 mm), and long but narrow rostrum (average ROL = 17.3 mm, ROB = 5 mm). I1 has a prominent posterior cuspule. I2 is generally posterolabially oriented. P1 and P3 are generally similar in size. Vestigial cingulum and small but frequently sharp parastyle in P4.

Comparisons: Only Hylomys species present in Borneo. Distinguished from all other congeneric species by black dorsal stripe in the shoulder area in adults, and long nasals and broad interorbital constriction (Supporting Information, File S1, Fig. S12). Posterior end of nasals generally extends to the level of the antorbital rim (26/36 specimens examined), while it does not in the other Sundaic Hylomys . Forefoot nails are longer than H. maxi , H. vorax , and, generally, than H. suillus . Supraorbital processes are more developed and prominent than in H. suillus , H. vorax , and H. parvus , but less robust than in H. maxi . I1 is less procumbent than H. vorax and H. suillus . I1 posterior cuspule is more prominent than H. suillus , H. vorax , and H. parvus . Braincase height at the occipitum (9.6–10.1 mm) is greater than H. parvus (8.6 mm), H. vorax (8.9–9.5 mm), and H. suillus (8.8–9.8 mm). Skull is narrower ( ROB = 4.6–5.5 mm, M1M1 = 8.2–11.3 mm) and molars are smaller (P4M3 = 7.7–8.6 mm) than H. maxi ( ROB = 5.2–6.4 mm, M1M1 = 10.9–12.5 mm, P4M3 = 8.3–9.9 mm).

Distribution, habitat, and natural history: Bornean endemic distributed from 1280 to 3413 m a.s.l. on Mt. Kinabalu ( Lim and Heyneman 1968, Camacho-Sanchez et al. 2019) and 1510– 2620 m a.s.l. on Mt. Trus Madi (authors’ unpublished data). It has also been recorded at c. 2050 m a.s.l. on Mt. Tambuyukon ( Camacho-Sanchez et al. 2019), 1800–1950 m a.s.l. on Mt. Alab (authors’ unpublished data), c. 2100 m a.s.l. on Mt. Murud ( Wiantoro et al. 2009), at an unknown elevation on Mt. Mulu ( Cranbrook 1982), and 1000 m a.s.l. in Bario, Kelabit Highlands ( MZUM-M 891). The species has been recorded in different habitats such as grass at the edge of forest, between rocks and logs next to a stream, under roots or fallen trees in oak mossy forest, in bamboo patches, grassy banks and flowerbeds around buildings, and inside an abandoned resthouse ( Phillipps 2016, authors’ unpublished data). In Kinabalu and Crocker Range Nationals Parks and Trus Madi Forest Reserve this species shares its habitat with Crocidura baluensis / Crocidura foetida s.l., Crocidura cf. neglecta , Chimarrogale phaeura , Palawanosorex ater , Tupaia montana , Leopoldamys sabanus , Maxomys alticola , Maxomys baeodon , Maxomys ochraceiventer, Niviventer rapit , Rattus baluensis , Sundamys infraluteus , Sundasciurus everetti , and Melogale everetti ( Camacho-Sanchez et al. 2019, Hinckley et al. 2022, authors’ unpublished data).

Four specimens collected in Kinabalu had remains of caterpillars, centipedes, beetles, and earthworms in their stomachs (Lim Boo Liat and Heyneman 1968). Two specimens collected in Trus Madi contained the remains of soft-bodied insects, caterpillars, and beetle larvae ( Harrison 1954). Specimens also ate tapioca and banana bait (authors’ unpublished data). Lactating females have been recorded in late-August (N = 3) and December (N = 1) (Lim Boo Liat and Heyneman 1968, this study). A gravid female with two embryos was recorded in mid-July ( USNM 292343). In March, a mature male and female were collected in the same trap ( BOR 309 and 312). Specimens (N = 11) collected in the same transects (N = 4) in Kinabalu and Crocker Range Parks were on average 155 m from each other (range: 90–220 m). Transects had never more than one adult male but could have more than one female or juvenile, suggesting parental care and/or territory overlap until adulthood or among females. Specimens were recorded in the morning (8:15 and 10 a.m.), afternoon (caught between noon and 7 p. m.) and at dawn, and were possibly also caught at night (authors’ unpublished data). This species makes ‘a sheltered nest out of leaves under rocks or logs’ ( Phillipps 2016).

Conservation: Recorded in Kinabalu, Crocker Range, Pulong Tau, and Mulu National Parks, and in the Trusmadi Forest Reserve ( Cranbrook 1982, Wiantoro et al. 2009, this study). The known distribution of H. dorsalis is mostly within protected areas, but further research is needed to determine population trends within these areas. Likewise, the combination of habitat suitability modelling and additional field surveys in Kalimantan are essential to re-assess the conservation status of H. dorsalis . Even though this species is distributed across most of northern Borneo, it is restricted to hill and montane forests over 1000 m a.s.l., which will probably decrease in area because of climate change.