Eptesicus pachyomus ( Tomes, 1857 )

Saikia, Uttam, Chakravarty, Rohit, Csorba, Gabor, Laskar, Mostaque Ahmed & Ruedi, Manuel, 2025, Taxonomic reassessment of bats from the Western Himalayas, India and description of a new species of the Myotis frater complex (Mammalia, Chiroptera, Vespertilionidae), Zootaxa 5644 (1), pp. 1-78 : 26-29

12. Eptesicus pachyomus ( Tomes, 1857)

(Oriental Serotine)

New material: 1 F, 01.06.2017, Salogra, Solan District , Himachal Pradesh, V /M/ERS/420 and 1 F , 01.06.2017, Salogra, Solan district , Himachal Pradesh, released; 1 F , 09.04.2018; 1 M 19.04.2019 & 1 M 05.05.2021, Mandal, Chamoli district , Uttarakhand, released .

Morphological description of specimen: Our specimens measured 50.6–51.2 mm in forearm length. The pelage on the dorsal side was light brown with a golden tinge and beige in the ventral side; individual hairs were darker on the roots. The muzzle and lower lips were flesh coloured and sparsely haired. The ears were broadly conical with a roundish tip and six distinct ridges on the inner sides. The tragus was short (7.1–7.2 mm) and blunt, slightly curved inward ( Fig. 11B ). The wing and interfemoral membrane were dark brown and without hairs. The thumb had a delicate curved claw.

The cranium was robust with greatest length in our Himachal specimen at 20.27 mm. The rostrum was broad (rostral width 7.5 mm), zygomatic arches were widely flared far exceeding the mastoid breadth. The sagittal crest was low, visible only from the parietal region and continued up to lambda. Palate was long and broad; its exterior margin lied at the level of posterior end of canine and the posterior margin spread well behind the 3 rd molar. The coronoid process of mandible was high and sharply descended to the condyle ( Fig. 12 ). The dentition was robust, upper toothrow measured 7.36 mm. The first upper incisor was large with a visible secondary cusp, the second one was very small. There was a diastema between the second incisor and the canine. The canine was well developed and exceeds the length of first premolar.

DNA: We obtained COI and CYTB sequences of a specimen from Solan in Himachal Pradesh (M 2207/ V / M/ERS/420), which proved to be nearly identical (<0.7% divergence) to homologous sequences from a specimen housed at the Field Museum ( FMNH 140422) and captured in the Karakar Pass, Pakistan ( GB OP157125 and OP137071 , respectively). Other Asian lineages in the serotinus group assigned by Juste et al. (2013) to Ep. pachyomus , including those sampled in Laos ( GB HM540269 , EU786850 ), China ( GB EU786841 ) or South Korea ( GB HQ580342 ) and curiously one specimen from Uttarakhand ( GB MN339179 ), formed a distinct clade of closely related lineages (i.e. within 2% sequence diveregence). This geographically widespread clade was, however, clearly distant genetically from the Himachal Pradesh and the Pakistani samples by 11–17% sequence divergence ( Tables S2 and S 3). These two latter samples were collected and sequenced independently for two mitochondrial markers, and both concur in being very divergent from any other known Asian lineages of Eptesicus . Other large species of Eptesicus , including Ep. serotinus turcomanus were also all distinct. Hence, this stricking molecular divergence is certainly not due to a potential laboratory artifact (see e.g., Sangster & Luksenburg 2020) but needs further scrutiny to be properly interpreted in terms of taxonomy.

Locality records and ecological notes: Uttarakhand: Mandal village (1630 m) in Chamoli district ; Himachal Pradesh: Salogra (1440 m) in Solan district (Present study) .

Two females of this species were caught in mist nets set around an artificial pond at Salogra at an elevation of 1440 m asl during early June. The collection locality is a small hamlet with agriculture fields and Pinus roxburghii trees. There is a cave nearby which holds populations of Rh. sinicus , Rh. lepidus and My. longipes although no Eptesicus was located there. It was a hot summer evening and a number of individuals of apparently the same species were seen drinking water from the pond. Both caught animals were lactating females which suggest the presence of a maternity colony nearby. In Uttarakhand, specimens were also caught in mist nets set over small streams in Mandal village in April and early May. In Afghanistan, this bat was reported from elevation between 570–830 m and was known to roost in ruins and other synanthropic places ( Benda & Gaisler 2015).

Taxonomic note: The largest of all Eptesicus species in the Indian subcontinent, Ep. pachyomus was traditionally considered to be distributed in the Indian Himalaya from Jammu and Kashmir to northeastern India (as “ Ep. serotinus ” in Bates & Harrison 1997). Based on analyses of morphology and both mitochondrial and nuclear DNA data, Juste et al. (2013) limited the distribution of Ep. serotinus to Europe and Central Asia whereas the Oriental representatives of the serotinus group were assigned to Ep. pachyomus , although they lacked any Indian or Himalayan samples in their molecular dataset. This new taxonomy was also supported by extensive morphological comparisons by Benda & Gaisler (2015) who included the Afghani taxon pashtonus as a synonym of Ep. pachyomus . According to Khandal et al. (2022), no precise locality was associated to the type of pachyomus described by Tomes (1857) from India and type locality might be somewhere in the Himalayas rather than the arid plains of Rajasthan. The cranial measurements of our Himachal Pradesh specimen appear among the smaller values reported by Benda & Gaisler (2015) for a series of specimens from Iran, Pakistan and Kashmir, but otherwise correspond morphologically to this taxon, including specimens from Afghanistan (op. cit.). Samples from further east and assigned to various other subspecies (i.e., andersoni, pallens or horikawai) are all larger bats. It is therefore puzzling to find a unique and basal mitochondrial lineage from Himachal Pradesh and northern Pakistan (genetically identical for both CYTB and COI genes) ( Figs 4 and 6). This lineage was very divergent from all other Oriental samples, including from one released individual from Uttarakhand (Chakravarty et al. 2022). As no nuclear marker were tested from the Himachal Pradesh or Pakistani samples, it is unclear whether this divergent mitochondrial lineage represents an introgressed variant inherited from an unsampled species, as has been shown in some Eurasian Eptesicus (Juste et. al. 2013, Artyushin et al. 2009), or whether Ep. pachyomus represents a complex of several taxa in the Himalayas.

Figures

FIGURE 4: Neighbor-joining tree reconstruction of examined vespertilionids, miniopterids and molossids COI sequences and based on the K2P matrix in Table S2. Branches are proportional to the number of mutational steps. Sequence names are composed of the first two letters of the genus, followed by the species name, the GenBank number (or field number for newly sequenced samples), and the region of origin. Samples from India are highlighted in bold face.

FIGURE 11. Portraits of some bat species recorded from the Western Himalayas during the present study.A) Ba. darjelingensis (released animal), B) Ep. pachyomus (ZSI–NERC V/M/ERS/420), C) Hy. affinis (ZSI–NERC V/M/ERS/638), D) Hy. savii (ZSI–NERC V/M/ERS/633), E) Mu. cf. aurata (released animal), F) Mu. cyclotis (ZSI–NERC V/M/ERS/425), G) Mu. huttonii (ZSI–NERC V/M/ERS/424), H) Mu. huttonii (released animal from Ansuya, Uttarakhand).

FIGURE 12. Dorsal, ventral, and lateral view of cranium and lateral and ventral view of mandible of Ep. pachyomus from Himachal Pradesh (ZSI–NERC V/M/ERS/420).