Eudiscoderma thongareeae Soisook et al., sp. nov.
Creators: name: Soisook, Pipat
name: Prajakjitr, Amron
name: Karapan, Sunate
name: Francis, Charles M.
name: Bates, Paul J. J.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Chiroptera
Megadermatidae
Eudiscoderma
Eudiscoderma thongareeae

description: Eudiscoderma thongareeae sp. nov.
Thongaree’s disc-nosed bat
Figures 1–11; Tables 1–2
Holotype. PSUZC-MM. 2014.157 (formerly BL130), adult male, body in ethanol, skull and baculum extracted, collected by A. Prajakjitr and Siriporn Thongaree on 11 April 2001.
Type locality. Sirindhorn Waterfall, Bala Forest, Halabala WS, Wang District, Narathiwat Province, S. Thailand, 5°48'08" N, 101°49'37"E, 135 masl.
Paratypes. PSUZC-MM. 2014.158 (formerly BL189), field number AP060517 -08, adult female, body in alcohol, skull extracted, Halabala Wildlife Research Station, Bala Forest, WS, Wang District, Narathiwat Province, S. Thailand, 5°48'01" N, 101°49'55"E, 140 masl, collected by A. Prajakjitr on 17 May 2006; PSUZC-MM.2014.164, field number SK141007.1, post lactating female, dry skin, skull extracted, Halabala Wildlife Research Station, Bala Forest, WS, Wang District, Narathiwat Province, S. Thailand, 5°48'04" N, 101°49'56"E, 150 masl, collected by S. Karapan and Phuchita Kong on 7 October 2014.
Measurements of the holotype (mm). FA: 66.41, E: 36.05, Tragus: 16.33, HB: 77.41, TIB: 35.46, HF: 18.12, 3MET: 49.44, 4MET: 53.45, 5MET: 58.27, 3D1P: 24.72, 3D2P: 42.56, GTL: 29.35, SL: 28.36, CCL: 26.22, ZB: 17.96, BB: 12.03, MW: 12.93, BCH: 11.98, PC: 4.01, RW: 8.24, C–M3: 10.96, C1–C1: 6.81, M3–M3: 9.45, C–M3: 12.37, M: 20.48, BL: 2.1.
Etymology. The species thongareeae is named in honour of Ms Siriporn Thongaree, the former head of Halabala Wildlife Research Station, who dedicated her life to researching the diversity and ecology of wildlife in the southernmost part of Thailand and to promoting its conservation. The proposed English name is “Thongaree’s disc-nosed bat”.
Diagnosis. Discriminating characters are as in the generic diagnosis but with the following additional features. This is a large megadermatid with a FA of 64.36–66.51 mm. The skull is large with a GTL of 29.22–29.44 mm and CCL of 26.01–26.22 mm (Table 2).
Description. (characters additional to those included in the diagnoses). Based on two females, the body mass is 30.0 and 36.2 g. The ears are very large (Table 2); they join over the forehead at about 30% of the height of the inner margins; these margins are covered with short orange-brown hairs on both the dorsal and ventral sides (Fig. 1 b). The tragus is bifurcate; the posterior process, with a length of 16.33-19.42 mm, is blade-shaped, and with a pointed tip; it is about half the height of the ear. The anterior process of the tragus is much shorter. The dorsal pelage is mid-brown basally and dark brown on the hair tips. The ventral pelage is paler, with whitish brown bases and greyish brown tips. Each wing is broad; the second phalanx of the third digit (3D2P; 41.75–42.56 mm) is distinctly longer than the first (3D1P; 23.52–24.74 mm). The ears, wing and tail membranes are dark brown (Fig. 1 a).
The skull is large (Table 2), with a robust rostrum. The sagittal crest extends almost horizontally from the anterior part of the interorbital region to the condyle (Fig. 6 b). The prenasal notch is relatively broad and rounded posteriorly (Fig. 5 b) and extends to the level of the first upper molar (M1). The posterior margin of the bony palate is adjacent to the midpoint of the third upper molar (M 3). Each zygoma is thick and without a dorsal process (Fig. 6 b).
The maxillary toothrow (C– M 3) is slightly convergent anteriorly. The upper premolar (P 4) is about two-thirds the crown area of the first upper molar (M 1) (Fig. 4 a). The first (M 1) and second (M 2) upper molars are almost square. The heels of P 4, M 1 and M 2 are characteristically rounded, well developed but not elongated (Fig. 4 a). The mesostyle of M 2 is situated medially, and in consequence, the labial margin of the tooth is broadly V-shaped. M 1 is about two-thirds the crown area of M 2; the third molar (M 3) is small and without a metastyle (Fig. 5 b).
In the lower dentition, the first (I2) and second (I3) incisors are tricuspidate and overlapping. The lower canine (C1) is robust and has a well defined cingulum but is without cingular cusps; it is about twice the height of the first (P 2) and second (P 4) lower premolars; it also exceeds both P 2 and P 4 in crown area (Fig. 4 b). The second lower molar (M 2) is the largest of the lower cheekteeth; in both the first and second molars (M 1 and M 2) the cristid obliqua is shortened in comparison to the protocristid and metacristid, in consequence the size of the talonid is reduced; in the third molar (M 3), the cristid obliqua is noticeably elongated. In all three lower molars, the protoconid exceeds the hypoconid in height when viewed laterally.
Echolocation. Eudiscoderma thongareeae emits multi-harmonic, low intensity Frequency modulated (FM) signals (Fig. 10). Up to six strong harmonics were observed, with a very low frequency first harmonic. The start frequency (sf) of the sixth (top) harmonic and the terminal frequency (tf) of the first (bottom) harmonic are 107.6–129.6 kHz (mean± SD: 113.9±7.9 kHz) and 11.2–14.0 kHz (mean± SD: 12.7±1.0 kHz), respectively. The maximum energy is usually found in the third harmonic with a peak frequency (fmaxe) of 53.1–55.1 kHz (mean± SD: 54.0±0.6 kHz) (Fig. 10 b, c). The call duration (d) and inter-pulse interval (ipi) are 1.8–2.6 ms (mean± SD: 2.1±0.2 ms) and 22.9–91.0 ms (mean± SD: 55.8±23.5 ms), respectively.
Genetics. DNA barcoding based on the mitochondrial gene COI clearly support genetic divergence between E. thongareeae and the sympatric M. spasma and M. lyra (Fig. 11) with a genetic distance of about 20.9% and 19.8%, respectively. It differs from C. cor by 23.7%. Although comparative genetic data for M. gigas and L. frons are not available for comparison in this study, morphological differences between them and E. thongareeae, as described above, are compelling.
The phylogenetic tree lacks strong bootstrap support for the higher level nodes, due to the high divergences within COI and its consequent limited resolution. Nevertheless, this suggests that not only is M. lyra highly divergent from M. spasma (>21% genetic distance), but it is not a sister species to M. spasma. It should therefore likely be considered in its own genus, Lyroderma (see discussion, below).
Distribution. Currently, Eudiscoderma thongareeae is only known from a small area of Bala Forest in the southernmost rainforest complex of peninsular Thailand (Fig. 2).
Ecological and conservation notes. Very little is known about the ecology of E. thongareeae. It was observed roosting in a hollow tree in dense evergreen rainforest near a stream (A. Prajakjitr, pers. comm.). The male specimen (holotype) was seen hunting a large beetle (order Coleoptera) nearby, before being caught in the middle of a mist net (about 2 m above the ground) set along a forest trail. Beetle remains were also found under the treeroost, suggesting that this species feeds on large coleopterans (A. Prajakjitr, unpublished data). Unfortunately, this roost was subsequently destroyed when strong winds severely damaged the tree. A female specimen (PSUZC-MM.2014.158) was caught on a rainy night with a hand net, while the bat was hanging in a building of the HBWRS, taking shelter from the weather. A recently collected female (PSUZC-MM.2014.164) was caught in a mist net (about 3 m above the ground), which was set in an open space in front of a building and close to the forest edge.
This species appears to be very rare. Despite extensive bat surveys in southern peninsular Thailand over the last 15 years, it is still only known from three specimens, all of which were collected from a small area of Bala Forest. This low capture rate is similar to the case of two other rare, recently discovered, bat species in the Bala Forest, Murina balaensis (Soisook et al. 2013) and Kerivoula krauensis (Douangboubpha et al. 2014). Much less research has been undertaken on the Malaysian side of the border, so it is possible that it also occurs there, but the rapid loss of lowland rainforest in peninsular Thailand and Malaysia suggests that it is very likely at risk and should be considered as a top priority for conservation.
Comparisons. Eudiscoderma thongareeae shares with the African Cardioderma cor the characters of a deep rostral depression and an enlarged coronoid process in each half mandible. In the dentition, like C. cor, the upper and lower canines are without discrete anterolingual cingular cusps; the small upper premolar (P2) is absent and the mesostyle of the first upper molar (M1) is situated labially and not reduced. Externally there are similarities in the morphology of the noseleaf. However, as can be seen from Tables 1 and 2, there are also many differences including the larger size of E. thongareeae; marked differences in the shape of the baculum (Fig. 9) and differences in the structure of the blood vessels in the interfemoral membrane. In the skull, there are differences in the shape, noticeably the absence in C. cor of an abrupt, step-like discontinuity between the rostrum and the anterior braincase (Fig. 6) and the absence in E. thongareeae of well developed preorbital and postorbital processes and an associated supraorbital flange (Fig. 8). There are also differences in the teeth. For instance, the upper and lower canines of C. cor are much less robust; the preparacrista is shortened and the postmetacrista elongated in the first upper molar (M1) of C. cor but about equal in E. thongareeae (Fig. 7); and the first lower premolar (P2) is enlarged in E. thongareeae but is relatively small in C. cor.
Eudiscoderma has some similarities with the other African taxon of megadermatid, Lavia frons. Of the three subspecies recognised for Lavia frons, two subspecies, affinis Andersen & Wroughton, 1907 and rex Miller, 1905, are described on the basis of size differences but they are considered poorly defined by Happold (2013). In both E. thongareeae and L. frons, the principal veins from the hind feet merge in the interfemoral membrane prior to entering the body (although in contrast to E. thongareeae, there does not appear to be a well defined blood vessel in L. frons running down the centre line of the membrane). The baculum shows some similarity in form, although that of E. thongareeae has a relatively longer and more robust shaft and shorter prongs (Fig. 9). The upper cheek teeth also show a similarity in structure, noticeably in the development of the mesostyles in M 1 and M 2 and in the relative sizes of the preparacrista and postmetacrista (Fig. 7). The small upper premolar (P 2) is absent in both taxa. However, there are also many significant differences. For instance, the noseleaf of L. frons is large, broad and with convex-sides and a truncated top; it has a longitudinal ridge which broadens at the base and is distinctively yellow in colouration (see Monadjem et al. 2010, figure 139; Happold 2013, figure 76). The pelage colour is also distinctly different, with that of L. frons characteristically tinged with yellow. In the skull, the rostrum of L. frons has only a shallow and narrow rostral depression but has well developed preorbital and postorbital processes and an expanded supraorbital flange (Fig. 8) and the coronoid process of each half mandible is not enlarged (Fig. 6); the upper and lower canines (C1 and C1) are less robust in L. frons and have anterolingual cingular cusps.
Eudiscoderma shares with the Australian Macroderma gigas the absence of the small upper premolar (P2), although this tooth is present in fossil species referred to Macroderma by Hand (1985). However, in most other dental features there are noticeable differences, including the structure of the upper and lower canines, premolars and molars (Table 1). In the skull, there are differences in the shape of the rostrum, braincase and coronoid process of each half mandible. Externally, there are differences in the shape of the noseleaf, the posterior leaf of which is elongate in M. gigas. In size, M. gigas greatly exceeds E. thongareeae (Table 2). In bacular morphology, M. gigas differs markedly, possessing a structure that comprises two separate bones, each shaped like a ‘bill-hook’ and with a saddle-like expanded base (Fig. 9 a).
Eudiscoderma differs from Megaderma lyra in all the characters listed in Table 1, noticeably including its baculum, which in M. lyra comprises two separate, short, thin bones (based on two specimens from Thailand and Vietnam respectively) (Fig. 9 c). Based on available descriptions, E. thongareeae also differs from all subspecies and synonyms of M. lyra (mapped in Fig. 2). Two of these, namely caurina Andersen & Wroughton, 1907 and sinensis Andersen & Wroughton, 1907, differ from the nominate form only in minor size differences. On the basis of figures included in the type descriptions and comments of Andersen and Wroughton (1907), the forms spectrum (Wagner, 1844) and schistacea (Hodgson, 1847) appear to be synonymous with typical lyra. The holotype of carnatica (Elliot, 1839) from western India was described as having only three teeth behind the canine in the upper toothrow. However Elliot (1839) himself referred the specimen to ‘ M. lyra?’ and its status remains unclear.
Eudiscoderma occurs sympatrically with the smaller M. spasma (Fig. 2). There are differences between the two taxa in external, bacular, cranial and dental characters (Table 1). Namely in the dentition, E. thongareeae has only one upper premolar (P4) since the minute, intruded premolar (P2) found in M. spasma is absent. Unlike M. spasma, the upper canine (C1) of Eudiscoderma is noticeably robust, especially in crown area; it is without an anterolingual cingular cusp and has a much larger posterior accessory cusp, which unlike that of M. spasma is not well-separated from the main cusp. In the upper molars, the structure shows some similarity between the two taxa, although in M. spasma, the postmetacrista in M1 is more elongated in comparison to the preparacrista than in Eudiscoderma (Fig. 7). The anterior braincase of E. thongareeae is more elevated than that of M. spasma and in consequence the profile of the upper braincase is almost straight whereas it is angular in M. spasma (Fig. 6). The rostrum of M. spasma is also less robust and without a deep rostral depression; however, the lack of development of preorbital and postorbital processes is comparable between the two taxa. Externally, size apart (Table 2), the morphology of the noseleaf (Fig. 1 b, d) is similar, although the posterior leaf of M. spasma is sometimes more angular than the rounded E. thongareeae. The vein pattern in the interfemoral membrane differs between the two taxa (Table 1). The bacula are of a similar general form but the relative proportions of shaft to prongs differ, with that of E. thongareeae having a more robust and longer shaft and shorter prongs (Fig. 9).
Megaderma spasma has 16 synonyms, all of which were variously accepted as valid subspecies by Simmons (2005). Geographically, they extend from the type locality of the nominate form in the Moluccas, Indonesia to those of horsfieldii Blyth, 1863 and ceylonense Andersen, 1918 described from western India and Sri Lanka respectively (Fig. 2). Of the synonyms which are most adjacent to the type locality of E. thongareeae, the forms abditum Chasen, 1940 and medium Andersen, 1918 from peninsular Malaysia and Singapore respectively, differ only in minor size differences from typical spasma. Of the Indonesian forms, siumatis Lyon, 1916, lasiae Lyon, 1916, and niasense Lyon, 1916 are island races, located off the west coast of Sumatra, that exhibit some small variations in external, cranial and dental dimensions. In Java, the form trifolium Geoffroy St. Hilaire, 1810 is considered to represent typical M. spasma on the basis of descriptions included in Andersen and Wroughton (1907). Specimens referred to the taxon pangandarana Sody, 1936 average slightly larger than typical trifolium. The taxon carimatae Miller, 1906 from Karimata Island, west of Borneo is a typical spasma but with slightly larger ears. The taxon natunae Andersen & Wroughton, 1907 was described on the basis of one specimen collected from Bungaran Island, off the north-west coast of Borneo. It is very large. However, the cranial and dental morphology clearly shows that it belongs to spasma; this agrees with the previous findings of Tate (1941). On mainland Borneo, the form kinabalu Chasen, 1940 differs only from typical spasma in minor size differences; and the form celebensis Shamel, 1940 from Sulawesi was described on minor differences in size and colour. According to Andersen and Wroughton (1907), specimens referable to the taxon philippinensis Waterhouse, 1843 from the Philippines are ‘in every respect indistinguishable from Celebes individuals.’ On mainland Southeast Asia, minus Andersen, 1918 from Cambodia, as the name suggests, is small. In Myanmar, the taxon majus Andersen, 1918, despite its larger size is clearly referable to spasma on the basis of its cranial and dental morphology; it was considered indistinguishable from the Indian taxon horsfieldii Blyth, 1863 by Sinha (1977). The Sri Lankan ceylonense Andersen, 1918 is a small race of spasma.
In terms of echolocation, the call characters of E. thongareeae are generally similar to those of the sympatric M. spasma and M. lyra, which is also known to occur in peninsular Thailand. The call records of individuals of M. lyra (n=2) and M. spasma from Thailand (n=1) and India (n=1) also have multi-harmonic FM signals with four to six strong harmonics (PS unpublished data). However, the fmaxe of the third harmonic of both species is slightly higher than in E. thongareeae. In M. lyra, the maximum energy sometimes lies in either the second harmonic, with a fmaxe of 41.4–49.9 kHz (mean±SD: 44.1±2.3 kHz) or third harmonic with an fmaxe of 58.3–68.5 kHz (mean±SD: 64.2±3.2 kHz). In M. spasma, the maximum energy is usually found in the third harmonic, with an fmaxe of 56.5–65.9 kHz (mean±SD: 59.8±3.9 kHz).
In the Australian M. gigas, Nelson (1989) summarised the call characters of this species as having a low intensity and frequency of the first harmonic with an fmax of about 20 kHz. The maximum energy is in the second and third harmonic with an fmaxe during the prey catching flight of about 60 kHz. The African species, Cardioderma cor, uses low intensity broadband and short duration FM sweeps with an fmaxe of 56.7±11 kHz (Taylor et al., 2005). For Lavia frons, detailed data are not available, although it is known to use low intensity broadband FM signals (Happold, 2013).
description: Published as part of Soisook, Pipat, Prajakjitr, Amron, Karapan, Sunate, Francis, Charles M. & Bates, Paul J. J., 2015, A new genus and species of false vampire (Chiroptera: Megadermatidae) from peninsular Thailand, pp. 528-550 in Zootaxa 3931 (4) on pages 532-546, DOI: 10.11646/zootaxa.3931.4.4, http://zenodo.org/record/238887