First records of Mops johorensis (Dobson, 1873), Northern Free-tailed Bat (Chiroptera, Molossidae), from Borneo, with new information on their genetics and echolocation calls

the journal of biodiversity data NOTES ON GEOGRAPHIC DISTRIBUTION 1047 Academic editor: Héctor Ramírez-Chaves Received: 14 May 2025 Accepted: 12 September 2025 Published: 29 October 2025 Copyright © The authors. This is an open-access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0) Abstract. This study presents the first confirmed records of Mops johorensis (Dobson, 1873) (Chiroptera, Molossidae) from Borneo. Specimens were recorded at three sites: Sabah (Sungai Kangkawat, 50 m a.s.l) and Sarawak (Lubok Antu, 30 m a.s.l and Mount Penrissen, 1200 m a.s.l). Echolocation analysis revealed site-based variation in call frequencies. Morphological comparisons showed subtle differences between Bornean and Peninsular populations. Genetic analysis using the mitochondrial COI gene showed minimal divergence between Bornean and Peninsular individuals. Spatial modelling identified hotspots for Molossidae in northern Sabah and central Sarawak, with habitat suitability strongly influenced by bat and cave density, climate, and land use. Key words. Canopy, diversity, forest species, new record, Sarawak, Sabah Khan FAA, Morni MA, William-Dee J, Kumaran JV, Jinggong ER, Rajasegaran P, Rosli QS, Mazlan N, Azman WNW, Reli SN, Daud US, Amat A, Bansa LA, Mahyudin A, Hasan NH, Senawi J, Azhar I (2025) First records of Mops johorensis (Dobson, 1873), Northern Free-tailed Bat (Chiroptera, Molossidae), from Borneo, with new information on their genetics and echolocation calls. Check List 21 (5): 1047–1058. https:// doi.org/10.15560/21.5.1047 INTRODUCTION The family Molossidae, commonly known as free-tailed bats, exhibits a broad distribution in both the Old and New Worlds, comprising 134 recognised species (Simmons and Cirranello 2025). These bats possess elongated, narrow wings that facilitate rapid and agile flight, along with a unique free tail that extends beyond the uropatagium (Payne et al. 1985; Francis 2008; Phillipps and Phillipps 2016). In Southeast Asia, 15 species of Molossidae in seven genera have been documented, with four species, namely Mops johorensis (Dobson, 1873), M. mops (de Blainville, 1840), M. plicatus (Buchannan, 1800), and Cheiromeles torquatus Horsfield, 1824 reported from Malaysia (Payne et al. 1985; Kingston et al. 2006; Francis 2008; Lim et al. 2017; Phillipps and Phillipps 2016). Previously, the known distribution of M. johorensis was limited to Peninsular Malaysia (Pulai, Johor; Krau Wildlife Reserve, Pahang; Mount Jerai, Kedah; Belukar Bukit, Terengganu) and Sumatra, Indonesia (Wilson and Reeder 2005; Kingston et al. 2006; Jayaraj et al. 2013; Roslan et al. 2016). This species was previously assigned to the genus Chaerephon Dobson, 1874 and was revised to Mops in 2024 (Mammal Diversity Database 2024). It is categorized as Vulnerable by the IUCN Red List 2025 due to its restricted range and likely small population size (Senawi et al. 2020). The species prefers high-canopy foraging (Kingston et al. 2006; Francis 2008), which complicates capture efforts. Most studies have focused on forest habitats, with sampling techniques leaning towards understory bats. Since this species prefers open spaces, it has been rarely recorded, and there is not much known about its ecology, echolocation, and genetics in Malaysia. 21 (5) · https://doi.org/10.15560/21.5.1047 21 (5): 1047–1058 First records of Mops johorensis (Dobson, 1873), Northern Free-tailed Bat (Chiroptera, Molossidae), from Borneo, with new information on their genetics and echolocation calls Faisal Ali Anwarali Khan1, Muhd Amsyari Morni1,2, Julius William-Dee1, Jayaraj Vijaya Kumaran3, Emy Ritta Jinggong1, Praveena Rajasegaran1,4, Qhairil Shyamri Rosli1, Norfarhana Mazlan1, Wan Nursyafinaz Wan Azman1, Siti Nurbaidzuri Reli1, Ummu Safiyyah Daud5, Amirrah Amat5, Lawrence Alan Bansa5, Azniza Mahyudin5, Noor Haliza Hasan5, Juliana Senawi6, Isham Azhar7 1 Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia 2 Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia 3 Faculty of Earth Science, Universiti Malaysia Kelantan Kampus Jeli, Locked Bag 100, 17600 Jeli, Kelantan, Malaysia 4 Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, Kuala Lumpur50603,Malaysia 5 Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia 6 Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 UKM Bangi, Selangor, Malaysia. 7 Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America Corresponding authors: Faisal Ali Anwarali Khan ([email protected]), Muhd Amsyari Morni (mmam[email protected]) Check List 21 (5) · https://doi.org/10.15560/21.5.1047 Khan et al. · First record of Mops johorensis in Borneo 1048 This research provides the initial verified records of M. johorensis in Borneo, thereby expanding its known distribution to Sabah and Sarawak. This report presents new distribution records, along with detailed ecological, genetic, and morphological data, addressing the significant knowledge gaps regarding this elusive species. Specifically, this report:(1) confirms the presence of M. johorensis in Borneo through genetic and morphological data, (2) describes its echolocation call structure and compares it with its sister species in Borneo, M. mops for which call data are available, (3) details its morphological characteristics including external and skull measurements, (4) maps the potential habitat suitability of Malaysian Molossidae across Borneo using a weighted overlay analysis of key ecological and spatial variables. STUDY AREA Field surveys were conducted at three locations in Borneo:Sungai Kangkawat Research Station, Imbak Canyon Conservation Area, Sabah (117.0596°E, 005.0748°N, 50 m a.s.l), Lubok Antu, Sarawak (111.817°E, 001.2894°N, 30 m a.s.l)andMount Penrissen, Sarawak (110.2167°E, 001.1167°N, 1200 m a.s.l)(Figure 1). These sites encompassmixed dipterocarp forest with highland and lowland areas. METHODS Bats were captured usinghigh mist nets (~10 m above ground), deployed from1800 hours to 2200 hours for five sampling nights. Captured individuals were identified, sexed, and measured in the field before release.External measurementsrecorded includedforearm length (FA), ear length (E), tibia length (TB), hind foot length (HF), tail-vent length (TV), and body weight (Wt). The craniodental measurements includecondyle-canine length (CCL), interorbital constriction (IOC), zygomatic width (ZW), width of braincase (WOB), mastoid width (MW) width from left upper canine to right upper canine (WUC1), width from left upper last molar to right upper last molar (WUM³), length from upper canine to upper last molar (CM³), mandible (MDB) and lower canine to lower last molar length (CM3) (Yoshiyuki and Lim 2005; Velazco and Petterson 2014; Morni et al. 2016). A few individuals of the target species were taken as voucher specimens for reference of the new records and deposited in the UNIMAS Zoological Museum (MZU). Echolocation calls were recorded using a Pettersson M500-384 USB Ultrasound Microphone (Pettersson Elektronik AB, Sweden). Bats were recorded in two conditions to analyze call variation: first in a room, flying less than 5 m above the ground, and second in open space, more than 10 m above the ground after release. Recording calls in both settings is important, as M. johorensis is a frequency-modulating bat that modifies its call structure according to the surrounding environment. The structure of each recorded call was analyzed using Kaleidoscope Call Viewer v. 4.5.5 (Wildlife Acoustic Incorporated, USA). All sonograms were generated using software’s standard default FFT size and overlap settings. For each call pulse, the following parameters were measured: Fstart refers to the initial frequency of the selected pulse (kHz); Fend denotes the terminal frequency of the selected pulse (kHz); Fpeak indicates the frequency at which maximum energy occurs (kHz); PD represents the duration of the pulse (ms); and PI is the interval between the start of one pulse and the start of the subsequent pulse (ms) (Kingston et al. 2003; Douangboubpha et al. 2014; Morni et al. 2016; Yoh et al. 2022). The calls were analysed in comparison to those of M. mops, a closely related species which call data are available in our lab. Tissue samples (muscle and liver) were preserved inabsolute ethanolfor genetic analysis. DNA was Figure 1. Previously known (black dot) and new localities of Mops johorensis in Malaysia; new records are from Mount Penrissen and Lubok Antu, Sarawak and Sungai Kangkawat, Sabah (black star). Inset map: position of Malaysia in South-east Asia. Check List 21 (5) · https://doi.org/10.15560/21.5.1047 Khan et al. · First record of Mops johorensis in Borneo 1049 extracted using aDNeasy Blood & Tissue Kit (Qiagen, Germany)following manufacturer protocols. A602-bp fragment of the cytochrome oxidase subunit I (COI) gene regionwas amplified using VR1 (5′-AGACTTCTGGGTGGCCAAAGAATCA-3′) and VF1 (5′-TTCTCAACCAACCACAAAGACATTGG-3) primers with the following PCR parameters: initial denaturation (94 °C for 3 min), denaturation (94 °C for 1 min), annealing (50 °C for 1 min), extension (72°C for 2 min), final extension (72°C for 5 min), and soaking (4°C). The PCR products were visualised, and successful products were outsourced to a private company for Sanger sequencing. In addition, a sequence ofM. johorensisfrom Mount Jerai, kindly shared by Isham Azhar, was included in the analysis. Three additional sequences of Tadarida latouchei (Thomas, 1920), T. teniotis (Rafinesque, 1814) and Otomops wroughtoni Thomas, 1913 from GenBank were included to provide better resolution of Molossidae in Southeast Asia. No other molosid bat sequences from this region are currently available. Phylogenetic analyses were conducted inMEGA11 (Tamura et al. 2021)using the maximum-likelihood (ML) method. The best-fit nucleotide substitution model was determined in MEGA11 using the “Find Best DNA/Protein Models (ML)” function, which identified the Tamura Nei + Gamma distributed with Invariant Sites (TN93+G+I) as the most suitable model (Akaike Information Criterion (AIC): 5868.861). ML analyses were performed with 1000 bootstrap replications to assess node support. Pairwise genetic distances were calculated in MEGA11 using the Kimura 2-parameter (K2P) model. Analyses were based on the same 602-bp COI alignment used for the ML tree without any missing data. Due to the paucity of occurrence records for M. johorensis, species-level distribution mapping was not feasible. To avoid misinterpretation, the data were pooled at the family level, which allow for more comprehensive and ecologically meaningful analyses. A total of 36 occurrence recordsfor these species were compiled from this study and UNIMAS Zoological Museum collections (Table 1). To analyse the distribution of molossid bats and assess their habitat suitability in Borneo, a weighted overlay analysis was conducted using ArcGIS Pro (ESRI 2024). Five environmental parameters were included: bat density, cave density, annual precipitation, annual mean temperature, and land use data (Table 2). Kernel Density Analysis was employed to visualize bat activity based on spatial point data, with bat density represented by a red gradient on the map. Cave density was derived from locations of known karst and cave sites published in google maps. Annual precipitation and annual mean temperature data were obtained from the WorldClim v. 2.1 database (~1 km² resolution) (Fick and Hijmans 2017). Land-use data were sourced from the European Space Agency, Land Cover CCI dataset. Each factor was assigned a weight based on its ecological significance in determining suitable habitats for Molossidae. The model categorized habitat suitability into five classes, ranging from very low to very high. Although the number of sampling sites is limited, the development of this model is important to provide insights into spatial and habitat suitability of this family, especially for generating information in areas with limited data and identifying areas with similar ecosystem that may be suitable for these species. RESULTS Chiroptera, Molossidae Mops johorensis (Dobson, 1873) Figures 2, 3 New records. BORNEO — Sabah • Tongod, Imbak Canyon, Sungai Kangkawat; 117.0596°E, 005.0748°N; 50 m alt.; 10.VIII.2018; F.A.A. Khan leg.; disturbed lowland forest, canopy-level mist-netting; 1 ♀, ICCA18-048 — Sarawak • Sri Aman, Lubok Antu; 111.817°E, 001.2894°N; 30 m alt.; 12.IX.2011; I. Azhar leg.; 1♀, MZU/M/4629 • Padawan, Mount Penrissen; 110.2167°E, 001.1167°N; 1200 m alt.; 9.XII.2015; I. Azhar leg.; montane forest, canopy-level mist-netting; 1♂, BH15-078. Identification. All three individuals have similar phenotype, as described by Francis (2008). They possess dark-brown upperparts and paler underparts. The upper lip is wrinkled. A “pocket” is present between the ears, formed by a flap of skin which is raised at the middle and extends backwards. Inside this pocket, long tuft hairs were detected. A high wing aspect ratio was observed, as these individuals have a long, narrow wing with pointed wingtips similar what has been reported by Norberg and Rayner (1987). The upper premolars have a small anterior one. The sagittal and lambdoid crests are not that obvious, whereas the anterior palatal crest is well developed. The skull characteristics of observed specimens match with those provided by Freeman (1981) and Francis (2008). Echolocation. The echolocation recordings revealed frequency differences between Sabah and Sarawak individuals. TheSarawak individualexhibited ahigher Fpeak (36.1–37.3 kHz), while theSabah individualhad abroader Fpeak range (23.3–35.1 kHz). The echolocation calls ofM. johorensiswere also compared toM. mops, which producedlower Fpeak at 22.6–23.9 kHz (Figure 3, Table 3). Check List 21 (5) · https://doi.org/10.15560/21.5.1047 Khan et al. · First record of Mops johorensis in Borneo 1050 Morphology. External and craniodental measurements of the Bornean M. johorensis specimens exhibited differ from previously recorded individuals from Peninsular Malaysia. The forearm length ranged from 48 to 50 mm, which is slightly longer than the mean value of 45.36 mm reported in earlier study (Roslan et al. 2016) (Table 4). Skull measurements showed variation in specific traits, with some measurements, such as mandibular breadth (MDB) indicating larger dimensions, while others suggested differences in shape and proportion rather than an overall increase in size (Table 5). The Bornean specimens also displayed a relatively broader mandible (MDB) with a comparable length of the lower dentary, suggesting variation in mandibular robustness rather than a uniform enlargement in size. Given the small sample sizes, these observations should be interpreted with caution. Additional specimens are required to determine whether the observed Table 2. Layers and variables used in suitability analysis, with details on resolution, category, year, and source. Layer Parameter Resolution Category/unit Year Source/Citation Environmental layer Land use ~300 m Land cover classes 2020 European Space Agency, Land Cover CCI dataset Bioclimatic variable Annual mean temperature ~1 km2°C 1970–2000 WorldClim v2.1 (Fick and Hijmans 2017) Bioclimatic variable Annual mean precipitation ~1 km2mm/year 1970–2000 WorldClim v2.1 (Fick and Hijmans 2017) Spatial data Bat-density map N/A Kernel density (records) Various This study + UNIMAS Zoological Museum collections Spatial data Cave-density map N/A Kernel density (sites) Various 12 caves identified through Google Map Table 1. Occurrence records of Malaysian molossid species used for species distribution modelling. Species Collection ID Locality Latitude Longitude Mops johorensis ICCA18031 Malaysia:Sabah, Sungai Kangkawat 005.050 117.116 BH15078 Malaysia: Sarawak, Lubok Antu 01.289 111.817 BH15079 Malaysia: Sarawak, Mount Penrissen 01.117 110.217 Mops plicatus MNP046 Malaysia: Sarawak, Mulu NP 04.092 114.896 MNP069 Malaysia: Sarawak, Mulu NP 04.092 114.896 MNP077 Malaysia: Sarawak, Mulu NP 04.092 114.896 MNP051 Malaysia: Sarawak, Mulu NP 04.092 114.896 MNP987 Malaysia: Sarawak, Mulu NP 04.092 114.896 MNP066 Malaysia: Sarawak, Mulu NP 04.092 114.896 MNP047 Malaysia: Sarawak, Mulu NP 04.092 114.896 MZU/M/256 Malaysia: Sabah, Gomantong Cave 05.530 118.075 MZU/M/257 Malaysia: Sabah, Gomantong Cave 05.530 118.075 MZU/M/258 Malaysia: Sabah, Gomantong Cave 05.530 118.075 MZU/M/259 Malaysia: Sabah, Gomantong Cave 05.530 118.075 MZU/M/302 Malaysia: Sabah, Gomantong Cave 05.530 118.075 MZU/M/266 Malaysia: Sabah, Gomantong Cave 05.530 118.075 MZU/M/303 Malaysia: Sabah, Gomantong Cave 05.530 118.075 MZU/M/544 Malaysia: Sabah, Kunak 04.683 118.250 MZU/M/545 Malaysia: Sabah, Kunak 04.683 118.250 MZU/M/546 Malaysia: Sabah, Kunak 04.683 118.250 MZU/M/547 Malaysia: Sabah, Kunak 04.683 118.250 MZU/M/548 Malaysia: Sabah, Kunak 04.683 118.250 MZU/M/549 Malaysia: Sarawak, Kuching 01.557 110.344 Mops mops KNP110923 Malaysia: Sarawak, Kubah NP 01.596 110.181 BA1246 Malaysia: Sarawak, Batang Ai NP 01.289 111.817 NNP14555 Malaysia: Sarawak, Niah NP 03.797 113.788 MZU/M/611 Malaysia: Sarawak, Bakun NP 02.762 114.055 Cheiromeles torquatus MZU/M/765 Malaysia: Sabah, Pulau Banggi 07.129 117.075 MZU/M/833 Malaysia: Sabah, Tabin WR 05.267 118.650 MZU/M/459 Malaysia: Sabah, Tenom 05.121 115.942 MNP24556 Malaysia: Sarawak, Mulu NP 04.092 114.896 MZU/M/1123 Malaysia: Sarawak, Miri 04.415 114.009 MZU/M/1432 Malaysia: Sarawak, Kapit 01.517 112.167 MZU/M/1175 Malaysia: Sarawak, Batang Ai 01.289 111.817 * BA = Batang Ai, BH = Borneo Highland, ICCA = Imbak Canyon Conservation Center, MNP = Mulu National Park, MZU/M = UNIMAS Zoological Museum/Mammal. Check List 21 (5) · https://doi.org/10.15560/21.5.1047 Khan et al. · First record of Mops johorensis in Borneo 1051 differences represent true population-level variation, individual morphological variability, or potential inconsistencies in measurement approaches between studies. Genetics. The study generated22 new COI sequences, including four sequences ofM. johorensis, four sequences ofM. mops, 11 sequences ofM. plicatus, and three sequences ofC. torquatus(Table 6). The analysis of theCOI gene (602 bp)revealed minimal genetic distance between Bornean and Peninsular Malaysian populations of M. johorensis, with onlyone transition mutation at position 504 (K2P: 0.2%). The ML tree strongly supported the monophyly of M. johorensis (bootstrap 100%), with its closest relative beingM. plicatus(K2P distance: 9%; bootstrap 86%), andM. mops forming amore distant clade (K2P: 12.8%; bootstrap 81%) (Figure 4, Table 7). The study also generated thefirst COI sequences forC. torquatus, contributing new genetic data for Southeast Asian molossid bats. Figure 2. Latero-ventral view of Mops johorensis, from Sungai Kangkawat, Imbak Canyon Conservation Area, Sabah (specimen ICCA18031). Figure 3. Sonogram on the structure of echolocation calls of Mops johorensis and M. mops. For each pair of the species calls, first call’s structure, (A–C) indicate high-frequency calls recorded in the open space at an altitude >10 m; second calls structure, (B–D) indicate low frequency calls recorded in a room <5m from ground. Check List 21 (5) · https://doi.org/10.15560/21.5.1047 Khan et al. · First record of Mops johorensis in Borneo 1052 Table 3. Call parameters of Mops johorensis. Parameters: Fstart = start frequency (kHz), Fend = end frequency (kHz); Fpeak = peak frequency (kHz), PD = pulse duration (ms), PI = pulse interval (ms). Species Recording conditions Call pulses Fstart (kHz) Fend (kHz) Fpeak (kHz) PD (ms) PI (ms) M. johorensis (n = 1) Sarawak i: High calls 7 43.9±4.9 39.0–48.8 30.6±3.0 27.6–33.6 36.8±0.6 36.2–37.3 6.3±1.4 4.9–7.8 104.3±20.2 84.1–124.4 ii: Low calls at ≤5 m from ground 7 35.4±4.5 30.9–39.9 13.7 25.1±0.7 24.4–25.8 4.3±0.3 4.0–4.6 80.0±8.5 71.5–88.5 M. johorensis (n = 1) Sabah i: High calls 5 54.8 ± 13.4 34.2 – 67.8 30.4 ± 6.4 20.1 – 36.7 25.9 ± 5.1 23.3 – 35.1 8.8 ± 5.7 4.5 – 18.2 120. 1 ± 46.6 77.9 – 180.4 ii: Low calls at ≤5 m from ground 5 26.8 ± 4.3 25.3 – 31.6 22.9 ± 2.3 20.4 – 24.9 28.5 ± 5.6 25 – 34.9 3.6 ± 1.2 2.5 – 4.9 124.6 ± 45.5 79.9 – 170.9 M. mops (n = 1) Sarawak i: High calls 12 37.4±2.3 35.1–39.8 16.9±1.3 15.7–18.2 23.3±0.6 22.6–23.9 11.8±1.9 9.9–13.7 275.6±26.6 249.0–302.2 ii: Low calls at ≤ 5m from ground 8 23.4 7.3±1.4 5.9–8.7 19.3±0.1 19.1–19.4 2.1±0.5 1.6–2.6 84.6±8.6 76.1–93.2 Table 4. External measurements (mm) and weight (g) for three specimens of Mops johorensis from Sungai Kangkawat, Imbak Canyon Conservation Area, Sabah, together with measurements of specimens from Francis (2008) and Roslan et al. (2016). Character This study (n = 3) Roslan et al. 2016 (n = 1) Francis 2008 (n = not specified) Forearm (FA) 48.83 ± 1.045 (48–50) 45.36 44–49 Head and body (HB) 72.58 ± 3.43 (70.15–75) 64.35 NA Tail to ventral (TV) 43.9 ± 1.91 (41.7–45) 34.02 36–43 Hind foot (HF) 10.93 ± 2.10 (8.8–11) 10.51 NA Tibia (TB) 19.87 ± 0.82 (19–20.63) 16.65 NA Ear length (E) 21.02 ± 3.57 (18.08–25) 11.36 NA Weight (g) 21.33 ± 1.53 (20–23) 20.6 15–25 Spatial analysis and habitat modelling. The density map of Molossidae in Borneo reveals distinct spatial patterns in hotspot distribution, influenced by variations in annual mean temperature. The highest density hotspots, ranging from 142 to 160, are concentrated in northern Sabah and central-northern Sarawak. Smaller, scattered hotspots are observed along the southern and western coastal areas. The background grayscale gradient illustrates annual mean temperatures, with lighter shades representing warmer regions and darker shades indicating cooler areas (Figure 5). Molossidae density was assigned the highest weight (30%) due to its indication of favorable environmental conditions and available roosting sites. Regions with very high suitability (red areas on the map) coincide with high bat density clusters, predominantly in central and northern Sabah and northern Sarawak (Figure 6). Cave density, weighted at 25%, also plays a crucial role, as many molossid species rely on caves for roosting and reproduction. High-suitability zones are observed around known limestone karst regions. Annual precipitation (20%) and annual mean temperature (20%) capture climatic influences on habitat viability, with high precipitation supporting lush vegetation and insect abundance, while warm temperatures optimize bat metabolic processes and activity. Land use, assigned a lower weight (5%), remains an important factor, with natural forests and protected areas showing higher suitability, while agricultural and urban areas exhibit lower suitability. DISCUSSION Range expansion and new records. Mops johorensis was previously considered confined to Peninsular Malaysia and Sumatra, with limited records from these areas (Wilson and Reeder 2005; Kingston et al. 2006; Jayaraj et al. 2013; Roslan et al. 2016; Lim et al. 2017). The identification of this species in Borneo, specifically Check List 21 (5) · https://doi.org/10.15560/21.5.1047 Khan et al. · First record of Mops johorensis in Borneo 1053 Figure 4. Maximum-likelihood (ML) tree of molossid bats in Southeast Asia. The phylogeny was generated with 1000 bootstrap replicates. Phylogenetic analysis was conducted in MEGA11. Sample locality information is provided after the GenBank accession number (BO = Malaysian Borneo; PM = Peninsular Malaysia; Malaysia = only country level information available). Full locality details are presented in Table 6. Table 5. Craniodental measurements (mm) for three specimens of Mops johorensis from Sungai Kangkawat, Imbak Canyon Conservation Area, Sabah, together with measurements of specimens from Jayaraj et al. (2013). Character This study (n = 3) Jayaraj et al. 2013 (n = 1) Condylo-canine length (CCL) 18.21 ± 0.34 (18–18.61) 17.66 Interorbital constriction (IOC) 4.92 ± 0.06 (4.88–4.99) 4.60 Zygomatic width (ZW) 12.13 ± 0.14 (12.04–12.29) 12.05 Width of braincase (WOB) 9.90 ± 0.042 (9.61–10.07) 9.74 Mastoid width (MW) 11.02 ± 0.12 (10.9– 11.15) 11.00 Width from left upper canine to right upper canine (WUC1) 4.48 ± 0.05 (4.44–4.54) 4.24 Width from left upper last molar to right upper last molar (WUM3) 8.45 ± 0.12 (8.35–8.59) 8.94 Length from upper canine to upper last molar (CM3) 7.2 ± 0.16 (7.02–7.32) 7.05 Mandible (MDB) 13.96 ± 0.18 (13.2–13.57) 12.57 Length from lower canine to lower last molar (CM3) 7.86 ± 0.21 (7.69–8.10) 7.52 Check List 21 (5) · https://doi.org/10.15560/21.5.1047 Khan et al. · First record of Mops johorensis in Borneo 1054 at Sungai Kangkawat, Imbak Canyon in Sabah, and Lubok Antu and Mount Penrissen in Sarawak, has substantially broadened its reported range. This indicates that M. johorensis may possess a broader distribution than previously recorded, yet it has gone undetected due to its elusive characteristics and tendency for high-altitude foraging (Kingston et al. 2003). Despite this range expansion, the species continues to be rarely observed. Table 6. New cytochrome oxidase I sequences of Molossids from Batang Ai, Imbak Canyon, Mount Jerai, Mount Penrissen and Mulu NP generated from this study Species Locality GenBank accession number Mops johorensis (n = 4) Malaysian Borneo: Sarawak, Mount Penrissen PV211244 Malaysian Borneo: Sarawak, Mount Penrissen PV211247 Malaysian Borneo: Sabah, Imbak Canyon PV211250 Peninsular Malaysia: Kedah, Mount Jerai PV211252 Mops mops (n = 4) Malaysian Borneo: Sarawak, Mount Penrissen PV211245 Malaysian Borneo: Sarawak, Mount Penrissen PV211246 Malaysian Borneo: Sarawak, Mount Penrissen PV211248 Malaysian Borneo: Sarawak, Batang Ai NP PV211257 Mops plicatus (n = 11) Malaysian Borneo: Sarawak, Mulu NP PV211253 Malaysian Borneo: Sarawak, Mulu NP PV211254 Malaysian Borneo: Sarawak, Mulu NP PV211255 Malaysian Borneo: Sarawak, Mulu NP PV211256 Malaysian Borneo: Sarawak, Mulu NP PV211258 Malaysia PV211259 Malaysia PV211261 Malaysia PV211262 Malaysia PV211263 Malaysia PV211264 Malaysia PV211265 Cheiromeles torquatus (n = 3) Malaysian Borneo: Sabah, Imbak Canyon PV211249 Malaysian Borneo: Sabah, Imbak Canyon PV211251 Malaysian Borneo: Sabah, Imbak Canyon PV211260 Figure 5. Density map of Molossidae in Borneo Check List 21 (5) · https://doi.org/10.15560/21.5.1047 Khan et al. · First record of Mops johorensis in Borneo 1055 During several nights of sampling, only a single individual of M. johorensis was captured at Sungai Kangkawat (from 83 bats), while one individual was recorded at Mount Penrissen (from 48 bats). This low capture rate is consistent with previous findings from Belukar Bukit, Terengganu, where the species was similarly observed in very low numbers (Roslan et al. 2016). One of the key contributing factors is likely its preference for foraging in high-canopy or open-space environments, making traditional ground-level mist-netting largely ineffective for its detection (Holbech 2020). Unlike earlier studies, this survey employed stratified mist-netting techniques that included canopy-level nets set at approximately 10–15 m above the ground, in addition to ground-level nets. These highnet placements, implemented using high poles across canopy gaps, enabled access to vertical foraging strata often missed by conventional methods. This approach likely contributed to the successful capture of M. johorensis and aligns with previous ecological characterizations of open-space aerial foragers, which are typically underrepresented in ground-based surveys (Lacki et al. 2007; Furey et al. 2009). While passive acoustic monitoring has the potential to enhance detection of such elusive species, its effectiveness is currently limited by the lack of a comprehensive and validated echolocation call library for M. johorensis. As such, targeted stratified mist-netting remains a vital method for detecting and studying rare, canopy-foraging bat species. Ecological flexibility. These new records expand the known distribution of the species beyond Peninsular Malaysia and Sumatra. Notably, our observations also extend the known ecological range of M. johorensis, which had previously only been reported from lowland evergreen forests (50–117 m a.s.l) (Wilson and Reeder 2005; Kingston et al. 2006; Jayaraj et al. 2013; Roslan et al. 2016). In contrast, we recorded individuals from a montane site at approximately 1200 m a.s.l. (Mount Penrissen) and from a disturbed forest area (Sungai Kangkawat), highlighting the species’ broader habitat tolerance than previously understood. Echolocation. Mops johorensis exhibits alternating call frequencies, a characteristic commonly associated with open-space aerial foragers (Jung et al. 2007; Ellerbrok et al. 2023). The Sarawak individual demonstrated high Fpeak (36.17–37.33 kHz), whereas the Sabah individual displayed a wider Fpeak range (23.3–35.1 kHz). Although these could reflect habitat structure and foraging behaviour (e.g. Falcão et al. 2021; Gilmour et al. Table 7. Pairwise distance test of Malaysian molossids (Kimura 2-parameter model). [1] [2] [3] [1] Mops johorensis (n = 4) [2] Mops plicatus (n = 11) 9.0 [3] Mops mops (n = 4) 12.8 11.2 [4] Cheiromeles torquatus (n = 3) 20.8 20.5 21.6 Figure 6. Suitability analysis model of Malaysian molossids.