Hylomys macarong Hinckley, Lunde & Hawkins, 2024

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 : 17-20

Hylomys macarong Hinckley, Lunde & Hawkins , sp. nov.

Hylomys sp. Bannikova et al., 2014: 501. Informal name.

Hylomys suillus microtinus, Best, 2018: 328 .

Hylomys suillus ssp. 2 Zeng et al., 2022: preprint fig. 3. Informal name.

Zoobank registration: urn:lsid:zoobank.org:act: A1305A1B-AA64-479F-9D88-59EAE5CCE2F0.

Holotype: USNM 320500 , an adult male collected by Bernard R. Feinstein on 21 July 1961 . The specimen consists of a museum study skin with accompanying cranium and mandible; skin is in relatively good condition, but is partially open along the suture line, and has a twisted right forelimb with the most external phalanx missing (clipped for DNA extraction), right ankle skin is pierced by tibia or calcaneus, partially chewed ears (possibly by ants, as reported for other specimens of the type series), and broken proximal and distal sections of tail, exposing the internal wire; skull is well prepared but has damaged pterygoid processes, left zygomatic arch, dorsal side of angular process and tips of left i1 and i2; and left P1 and occipital condyle are missing (unerupted and broken, respectively). Total length 165 mm, tail 25 mm (18% HB), hindfoot 27 mm, ear length 18 mm. Skull measurements in Supporting Information, Table S2. 3D surface scans of this holotype skull are available at MorphoSource: https://doi.org/10.17602/M2/M560006 (cranium); https://doi.org/10.17602/M2/M560011 (mandible). Pictures of this holotype skin and skull are shown in Figures 7B and 8B . DNA sequences associated with this holotype have been deposited in GenBank: OR138081 and OR554435 .

Type locality: ‘ Fyan, Lam Dong, Vietnam’ (now known as Phú Sơn , Lâm Hà District, Viet Nam, 11.88º N, 108.2º E, c. 1200 m a.s.l.; source: US military intelligence).

Paratypes (2): USNM 320492 , 320495 : same as type locality ; USNM 320485 : Thac Datan La , Dalat, Lam Dong, Viet Nam, c. 1450 m a.s.l. ; USNM 320490 : 1 km E of Poste De Mdrak , Dac Lak, Viet Nam , c. 500 m a.s.l.

Representative DNA sequences: Deposited (or already available) in GenBank with the following accession numbers: KF783150, KF783151 (cytochrome b, two representatives), (mitochondrial genomes, two representatives). New sequences: OR138079-OR138081 (mitochondrial genomes, three representatives), OR554432-OR554435(GHR, four representatives). DNA sequences associated with the following voucher specimens: USNM 320485, 320490, 320495, 320500 (this study); USNM 320485, 320501 (Zeng et al. 2022); ZMMU S-190307 ( Bannikova et al. 2014).

Etymology: The specific name ‘macarong’, which means vampire in Vietnamese (Ma cà rồng), acknowledges the long fangs (first upper incisors) that characterize mature males of this species. We suggest the common names Dalat Gymnure, Chuột Voi Đà Lạt, and Gimnuro de Dalat, in English, Vietnamese and Spanish, respectively, given that this species is just currently known from the Da Lat and Dak Lak Plateaus and surrounding lowlands, in southern Viet Nam.

Diagnosis: A medium-sized Hylomys (average HB = 138.4 mm, GLS = 34.8 mm) characterized by a rusty chest coloration in males ( Fig. 7B ; possibly just present during spring/summer, since specimens collected in April and possibly winter (inferred due to long, soft, and thick pelage), lacked this coloration), bicoloured and long tail (average T = 23.2 mm, T/HB = 16.8%), light brown feet, short hindfoot (average HF = 23.5 mm, HF + nail = 25.7 mm), ears are uniformly brown-coloured and relatively long (average E = 18.1 mm, E/GLS = 52.6%). Its skull is characterized by: obtuse-angled notch between premaxilla tips; narrow rostrum (average ROB = 5.2 mm); long nasals (average NL = 13 mm; NL/GLS = 37%) that extend to the level of the antorbital rim; highly to moderately developed supraorbital processes; conspicuous and posteriorly expanded horizontal crest behind infraorbital canal; alisphenoid canal intermediate in length among other Hylomys species (average ASC = 0.5 mm); interior side of ectotympanic anterior process elongated and greatly expanded anteriorly; deep braincase at the occipitum (average BD = 9.7 mm); robust mandibular ramus (average LAP = 10.1 mm) with broad coronoid process; very long first upper incisor (average I1 = 3.3 mm), particularly in males (average I1 = 3.6 mm males, 2.9 mm females; Supporting Information, Fig. S7 ), which is slightly projected towards lingual side, so that space between incisors generally narrows towards the tip; P4 labial cingulum absent or poorly developed.

Comparisons: In summer, easily distinguished from its closest geographical and genetic relative, H. peguensis , by its rusty venter coloration (in males), which contrasts with H. peguensis ’s pale grey coloration ( Fig. 7 ). White rim in ear is absent vs. present in H. peguensis (except in Cambodian specimen). Rostrum is longer (average = 15.1 mm) and narrower (average = 5.2 mm) than H. peguensis (average = 14.6 mm, 5.5 mm). Nasals are longer (average = 13 mm) vs. shorter (average = 11.8 mm) in H. peguensis . Conspicuous and posteriorly expanded horizontal crest behind infraorbital canal vs. less prominent and expanded in H. peguensis . Alisphenoid canal shorter (average = 0.5 mm) vs. longer (average = 1 mm) in H. peguensis . Interior side of ectotympanic anterior process elongated and greatly expanded anteriorly vs. not expanded in H. peguensis . Braincase at the occipitum is deeper (9.4–10.2 mm) vs. flatter (9–9.6 mm) in H. peguensis . Mandibular ramus broader (average LAP = 10.1 mm) vs. narrower (average LAP = 9.1 mm) in H. peguensis , in fact, these species can be diagnosed through the combination of angular process length and rostral breadth (Supporting information, File S1, Fig. S8 ). Coronoid process is broader vs. narrower in H. peguensis , making the space between the distal region of coronoid and condylar processes frequently more narrow/acute in H. macarong than in H. peguensis ( Fig. 8 ). I1 sexually dimorphic and longer (males: 3.6, 2.6–4.5 mm, females: 2.9, 2.6–3.15 mm) vs. sexually monomorphic and shorter (males: 2.6, 2.1–3 mm, females: 2.6, 2.4–3.1 mm) in H. peguensis . I1 generally slightly projected towards lingual side, so that space between incisors generally narrows towards the tip vs. I1 slightly projected towards labial side, so that space between incisors does not narrow towards the tip in H. peguensis . I2 projected posterolabially vs. posteriorly in H. peguensis . P4 labial cingulum absent/poorly developed vs. generally well developed/conspicuous in H. peguensis .

It is currently thought to have a highly disjunct allopatric distribution with Malayan H. maxi , from which it can be easily distinguished based on its shorter rostrum (RL: 14.6–15.7 vs. 16.1–18.2 mm), upper toothrow (IM3SB: 16.1–17.4 vs. 17.6–19.6 mm) and molars (P4M3: 7.6–8.3 vs. 8.3–9.9 mm). Additionally, it can also be diagnosed from H. maxi due to its generally longer first incisor and through the combination of angular process length and rostral breadth (as with H. peguensis ; Supporting information, File S1, Figs S7 , S 8 ).

Distribution, habitat, and natural history: Currently known from the Langbian/Da Lat and Dak Lak Plateaus and surrounding lowlands, in southern Viet Nam. Collected at c. 50–80 m a.s.l. in semi-deciduous dipterocarp forest with extremely dense understory with shrubs, saplings, and lianas; at a site at 1700 m a.s.l. containing both pine savanna (dominated by Pinus kesiya ) with a dense grass cover and a tract of primary evergreen hill forest ( Adler et al. 2001); and at a Dalat pine forest at c. 1520 m a.s.l. (USNM 269789; J.F. Rock). Specimens were collected under log in grass (N = 6), grass (N = 5), grass area in wood edge (N = 5), under log (N = 1), under broadleaf herbaceous shrub near wet spot (N = 1), and at base of Pandanus in moist area (N = 1). Not recorded in bamboo patches or inside fagaceous forest, as with some sympatric rats, squirrels, and treeshrews (Feinstein’s field notes, USNM Mammal Division archives). Shares its habitat with Crocidura spp. , Suncus murinus , Tupaia belangeri , Bandicota savilei , Berylmys berdmorei , Berylmys mackenziei , Chiromyscus langbianis , Leopoldamys milleti , Maxomys moi , Maxomys surifer , Mus carolii , Mus pahari, Niviventer mekongis , Rattus andamanensis, Rattus argentiventer , Rattus rattus, Vandeleuria oleracea , Dremomys rufigenis s.l., and Menetes berdmorei (Feinstein’s field notes, USNM Mammal Division archives; USNM collection; Adler et al. 2001).

A juvenile female and adult male were collected in the same trap during two consecutive days, perhaps suggesting parental care and/or male territory overlap with offspring at least until adulthood.Two juvenile female specimens were also collected 3 m away from each other during two consecutive days. Mature males have a reddish ventral coloration in July, which subadults and females lack, suggesting it might represent a sexual character. This coloration might last until late September, since one specimen (USNM 320485) was moulting it but still had enlarged testes (13 × 6 mm; using H. peguensis specimens as a reference), perhaps suggesting end of breeding season. One female with six mammae was recorded by mid-December (USNM 320490), and juveniles have been recorded from mid-September to mid-October. Specimens were collected with snap traps baited with banana and manioc.

Conservation: Recorded in Bu Gia Map and Cat Tien National Parks ( Bannikova et al. 2014) and in proximity to Kalon Song Mao and Hon Ba Nature Reserves (Supporting information, Table S1 ). Viet Nam now has the second-highest rate of deforestation in primary forests ( Poyarkov et al. 2023). Co-distributed species with a potential similar extent of occurrence than that currently known for H. macarong , such as Pygathrix nigripes (Milne-Edwards 1871) , Trachypithecus margarita (Elliot 1909) , Nomascus gabriellae (Thomas 1909) , and Murina harpioloides (Kruskop and Eger 2008) , are listed as endangered or critically endangered (IUCN Red List of Threatened Species 2023). Further research is needed to assess its tolerance to habitat degradation, and to evaluate whether this species is present in other potentially suitable protected areas, such as Ea So, Krong Trai, Nam Nung, and Nam Kar Nature Reserves, and Lo Go Xa Mat and Ta Dung National Parks, in Viet Nam, and Lumphat, Phnum Prech, and Phnom Namlear Wildlife Sanctuaries in Cambodia.

Comments: Specimens from Kon Tum province, Central Highlands region of Viet Nam (MNHN1929320–5) have not been sequenced but were clustered in the morphospace of H. peguensis and were thus assigned to H. peguensis in univariate descriptive statistics and bivariate plots.

Figures

Figure 7. Dorsal and ventral views of the skins of (A) Hylomys peguensis (USNM583813, neotype), and (B) Hylomys macarong(USNM 320500, holotype). Photo credits:Katie Sayers.

Figure 8. Skulls of (A) Hylomys peguensis (USNM583813, neotype) and (B) Hylomys macarong (USNM 320500, holotype).All images are at the same scale.Photo credits: Katie Sayers.