Pseudoromicia mbamminkom, Grunwald & Demos & Nguéagni & Tchamba & Monadjem & Webala & Peterhans & Patterson & Ruedas, 2023

Grunwald, Amanda L., Demos, Terrence C., Nguéagni, Yvette, Tchamba, Martin N., Monadjem, Ara, Webala, Paul W., Peterhans, Julian C. Kerbis, Patterson, Bruce D. & Ruedas, Luis A., 2023, A review of bats of the genus Pseudoromicia (Chiroptera: Vespertilionidae) with the description of a new species, Systematics and Biodiversity 21 (1), pp. 1-18 : 7-15

Pseudoromicia mbamminkom sp. nov. Mbam Minkom Serotine

Figs 7–13 , Table 4

Holotype. FMNH 240714 , adult female, not pregnant or lactating. Body preserved in ethanol, with skull extracted and cleaned. Specimen collected by ALG, YN, and LAR, on 14 August 2019; field catalogue number ALG 23.

Type locality. Cameroon: Centre Region, Lekie Department; NW slope of Mount Mbam Minkom , 3 ° 58.156'N, 11 ° 22.840'E (datum: WGS84), 785 m, near the village of Nkolakie (also spelled Nkolakie); the locality is illustrated as Camp 2 in Fig. 1 . The specimen was collected in secondary forest, using a mist net set across the Bitemgu River.

Etymology. Anoun in apposition, named for the type locality, the most prominent summit in its namesake Mbam Minkom Massif, an isolated gneiss inselberg formation emerging from the surrounding lowland forest matrix.

Distribution. Based on a single record at an elevation of 785 m on Mount Mbam Minkom in the Centre Region of Cameroon ( Fig. 1 ).

Diagnosis. Pseudoromicia mbamminkom is a large-sized member of the genus Pseudoromicia ( Table 1 , Figs. 3 , 4, 6). Adark brown muzzle and wings distinguish it from the white-winged members of the genus ( P. isabella , P. rendalli , P. nyanza , and P. tenuipinnis ). It is similar in size and appearance to its putative sister species P. kityoi ; however, cranially, P. mbamminkom and P. kityoi differ in the lateral view: the dorsal aspect of the rostrum is angled continuously from the braincase in P. mbamminkom while being markedly depressed in P. kityoi ( Fig. 7 ). The rostral facies of the palatal emargination, or notch, is rounded and scallop-shaped in P. mbamminkom , but narrower and U-shaped in P. kityoi . The occipital condyles are more ventrally pronounced in P. mbamminkom and the inion is unobtrusively rounded in contrast with the markedly prominent inion in P. kityoi . The caudal midline projection of the palatine bone is lacking in P. mbamminkom but present in the holotype of P. kityoi ; however, this may be an intraspecifically variable character in other taxa and should be evaluated further with additional specimens. Dentally, the cingulum surrounding the lingual aspect of I1 is continuous in P. mbamminkom , and broad in proportion to width of the incisor ( Figs. 8 and 9). The cingulum is narrower and discontinuous between the lingual and labial aspects in P. kityoi . The hypocone basin in PM2 is reduced in P. mbamminkom with respect to P. kityoi . Lower m1 and m2 in P. kityoi have a broadly extended posterior lingual shelf not present in P. mbamminkom . Although overlapping in individual cranial variables with other members of Pseudoromicia ( Table 1 ), it can be distinguished more easily by means of the PCA of cranial dimensions ( Figs. 3 and 4), in particular along PC2, which loads most heavily on breadth of postorbital constriction and braincase, as well as mastoid breadth. Indeed, P. mbamminkom has the narrowest interorbital region of known Pseudoromicia species. In addition, P. mbamminkom is distinguished genetically from other members of Pseudoromicia by a number of mitochondrial Cytb substitutions ( Table 3 ).

Description

The only known specimen of Pseudoromicia mbamminkom is a large-sized pipistrelle-like bat (external and craniodental measurements listed in Table 1 ; wing measurements in Table 4 ). The dorsal pelage is reddish-brown (Sepia; Color 219 of Smithe, 1974) with uniformly coloured hairs ~ 5.0 mm in length ( Fig. 10 ). The ventral pelage is bicoloured and slightly shorter (~ 4.0 mm) than the dorsal pelage. Individual ventral hairs are reddish-brown (Sepia; Smithe, 1974) at the base with tips of drab grey (Drab-grey; Colour 119 D of Smithe, 1974) eventually fading into uniformly coloured drab-grey nearing the uropatagium ( Fig. 11 ). The wing and tail membranes are dark brown, as are the muzzle and ears. Ear length is typical for Pseudoromicia : 12 mm (vs. 12.2 ± 1.11, 9–14 mm across other species in the genus) and rounded. The tragus is broad (2.9 mm), blunt, and 7.0 mm in length, with a curved outer margin typical of the genus ( Monadjem et al., 2013; Monadjem, Richards, et al., 2021 [as Neoromicia ]; Fig. 12 ). The plagiopatagium attaches at the metatarsals, and a keeled calcar is present ( Fig. 13 ). In lateral profile, the cranium is relatively flat ( Fig. 7 ), and the rostrum angled continuously from the braincase. Sagittal and lambdoidal crests are absent. Pseudoromicia mbamminkom has a dental formula typical of the genus, I 2/3, C 1/1, P 1/2, M 3/3 - 32. I 1 is unicuspid and I 2 slightly less than half the length of I 1. P 1 is absent; the single upper premolar present in the toothrow is homologous with P 2.

Biology

Because Pseudoromicia mbamminkom is known only from a single specimen, almost nothing can be said about the biology of the species. There is weak support suggesting P. mbamminkom as sister to P. kityoi . Like this new species, P. kityoi is only known from a single locality in the Mabira Forest Reserve in the Central Region of Uganda (0 ° 26.706 ' N, 32 ° 53.3256 ' E; ~ 1120 m asl) where two specimens were collected. The holotype of P. mbamminkom was not in an obviously reproductive status at the time of collection. No information other than that presented above is available on the biology of P. mbamminkom .

Discussion

Biogeography

The type locality for P. mbamminkom ( Fig. 14 ) is approximately equidistant between Mabira Forest Reserve in Uganda (0 ° 26.706 ' N, 32 ° 53.3256 ' E), type locality of P. kityoi ; ~ 2426 km), and Mt. Nimba (07 ° 29 ' N, 08 ° 35 ' W), on the Liberia–Guinea–Sierra Leone border; type locality of P. roseveari ~ 2257 km). Notwithstanding the lack of resolution in our molecular analyses, these data, albeit based on a single mitochondrial locus, suggest P. kityoi as sister to P. mbamminkom , but also places it definitively in a clade with P. roseveari and P. kityoi . This association suggests that the three species may be relicts of a single widespread species that originated in West Africa (“white-winged” group) then spread east across the tropical moist broadleaf forest reaching into East Africa, and now are restricted to a few upland rainforest patches in West Africa ( P. roseveari ), in outliers of the Cameroon Volcanic Line region ( P. mbamminkom ), and the Lake Victoria area ( P. kitoyi ). The smaller, white-winged species are hypothesized to be ancestral based on our molecular results, and the larger, dark-winged taxa dispersed to East Africa then back to West Africa (e.g., P. mbamminkom , P. roseveari ). This also illustrates the potential biogeographic importance in this group of species of the Dahomey gap, the zone of aridity in Togo, Benin, and neighbouring states, between the Volta and Weme Rivers, that breaks up the rainforest into Upper and Lower Guinea Rainforests.

The Dahomey Gap has long been acknowledged as a significant biogeographic barrier (e.g., Booth, 1954, 1958; Grubb, 1978; Moreau, 1969). The genetic distances between each of these three species ( Table 3 ; 5.2% to P. kityoi and 5.1% to P. roseveari ; 5.1% between P. kityoi and P. roseveari ), based on their magnitude, are more supportive of the hypothesis of Robbins (1978), who proposed a biogeographic barrier role for the Volta and Niger Rivers, rather than the arid vegetation belt as the primary vicariant mechanism ( Booth, 1958). The presence of the arid belt is hypothesized to be relatively recent (9 ¯ 4.5 KYA; Demenou et al., 2018). However, successive cycles of xeric and mesic climates leading to deforestation and reforestation ( Carcasson, 1964; Demenou et al., 2016, 2018; Livingstone, 1975; Lonnberg, 1929; Moreau, 1952, 1963, 1966; Rowan et al., 2016) indicate that the arid corridor also may have played a vicariant role during glacial cycles. Notwithstanding, the presence of the Dahomey Gap, and the Volta, Weme, and Niger Rivers, all would reinforce the distinction between the faunas of Central and West African mountains, leaving what Grubb (1978: 159) called a “remarkable affinity between East African and Cameroon highland fauna”.

In recent years, a large number of African bat species either have been described or documented without being formally described (e.g., 12 undescribed species of Rhinolophus , including sympatric morphologically cryptic species: Demos et al., 2019; 11 undescribed clades of Miniopterus: Demos et al., 2020 ). This suggests that the Afrotropical bat fauna, although characterized as depauperate relative to other tropical regions, likely has been under-studied and under-sampled ( Herkt et al., 2016; Tanshi et al., 2022a), particularly in morphologically conservative groups such as vespertilionid bats. This work supports the aforementioned studies in proposing that there is higher bat species richness in Africa than has been intimated in taxonomic compendia and emphasizes the need for additional taxonomic sampling and comprehensive phylogenetic studies. This phenomenon is further exemplified when considering recent systematic work focused on African pipistrelle-like bats, which has revealed high levels of cryptic diversity in the group ( Hutterer et al., 2019; Monadjem, Demos, et al., 2021). The tropical African bat fauna currently is considered to contain fewer species than that of tropical regions of South America or Southeast Asia ( Tanshi et al., 2022b). However, the accelerating rate of bat species discovery in Africa led Patterson et al. (2021) to suggest that, far from the 224 species known to Happold and Happold (2013; Van Cakenberghe and Seamark, 2021, list 344 extant species), the actual number of bats on the African continent “will eventually exceed 400 species of bats”.

Conservation

Conservation of Mbam Minkom’ s forests is vital to the preservation of biodiversity in Cameroon as well as to the economic and ecological stability of neighbouring communities. The MbamMinkom Massif (MMM), covering ~ 4500 ha, is bisected by several springs, streams, and river gorges, all taking their rise from the mountain, thereby making it a major water catchment for the surrounding area and beyond. It not only provides clean water, but also is a major source of livelihood for at least 10 adjacent fringing villages. MMM is a region of exceptional ecological and economic importance, yet the fauna remains poorly studied. Because of human–- wildlife conflicts, subsistence hunting, and over-harvesting resulting in habitat loss, large mammals are extremely rare. However, the remaining forest fragments still harbour charismatic flagship species of global conservation concern, such as one of the few remaining populations of Grey-necked Rockfowl ( Picathartes oreas; Passeriformes : Picathartidae ) and Giant Ground Pangolin (Smutsia gigantea; Pholidota : Manidae ). Notwithstanding its enormous natural value, the MMM ecosystem is one of the most endangered in Cameroon because of the lack of legal conservation frameworks and exposure to increasing human pressure from the nearby (8 km) capital city, Yaounde ( Simo et al., 2009). Based on the very limited information available to us on P. mbamminkom , the new species should be considered by IUCN as Data Deficient. Notwithstanding, the extent of occurrence may be less than 100 km 2, based on the extent of forest and upland habitat constituting the MMM. In addition, at present, the species is known to exist only at a singular location; thus, there is an urgent need to determine whether this apparent geographic restriction and uncommonness is real or artefactual. The area, extent, and/or quality of habitat was observed to be declining. As a result of our assessment of conditions on the ground, P. mbamminkom may be facing a higher risk of extinction in the wild than its IUCN designation of DD would suggest. Certain taxa that were either unassessed by the IUCN, or Data Deficient, were found recently to be considerably more likely to be threatened than assessed species ( Caetano et al., 2022). Similarly, over half of all DD species sampled – including over 60% of mammals – have been predicted to be threatened by extinction ( Borgelt et al., 2022). The rapidly shrinking forest habitat of the Mbam Minkom Massif likely is cause for concern with respect to the conservation status of all the flora and fauna of the region: at least one other mammal species – Leimacomys buettneri , the Togo mouse, ( Rodentia : Muridae ) – representing a monotypic subfamily (Leimacomyinae) and known by two specimens from a single locality in Togo, has been hypothesized to be extinct in similar habitat under similar conditions of habitat degradation ( Amori et al., 2016), and has not been rediscovered despite at least two expeditions dedicated to searching for it.

The recent systematic evaluations of vespertilionids, and in particular pipistrelle-like vespers, have resulted in the illumination of vast amounts of previously unresolved taxonomic diversity. We hope that our description of an additional member of Pseudoromicia will encourage further efforts to more closely examine currently existing specimens and continue surveying under-sampled regions in Africa to assess species boundaries, and to resolve the taxonomy of other cryptic lineages in vespertilionids. These efforts are essential to the conservation of bat diversity in Cameroon in particular, as well as Africa as a whole.

Figures

Figure 1. Land cover map showing collecting camps and villages surrounding the Mbam Minkom Massif, Lekie Department, Centre Province, Cameroon. Coordinates (Datum: WGS84) of each collecting camps are as follows, Camp 1: 3ǫ57.4810 N, 11ǫ22.9990 E, 1074 m; Camp 2: 3ǫ58.1560 N, 11ǫ22.8400E, 785 m; Camp 3: 3ǫ55.0060 N, 11ǫ22.4000 E, 884 m; Camp 4: 3ǫ55.0720 N, 11ǫ22.6390 E, 829 m. Inset (upper): location of Mbam Minkom Massif within Cameroon’s Centre Region; Inset (lower): location of Cameroon within Africa. Map created using ArcGIS software by Esri (2020) including datasets from: USGS, land use/land cover data from ESA’s Sentinel-2 produced by Esri, Microsoft, and Impact Observatory (2021); village location from Awa et al. (2009).

Figure 7. Dorsal, ventral, and lateral view of the skull of the holotype of Pseudoromica kityoi (right) and the holotype of Pseudoromicia mbamminkom sp. nov. (left).

Figure 8. Scanning electron micrograph (composite) of the upper (left) and lower (right) dentition of Pseudoromicia mbamminkom sp. nov. (not to scale). Length of upper toothrow: 4.75 mm; length of lower toothrow: 5.68 mm.

Figure 9. Comparison of the upper and lower dentition of Pseudoromicia mbamminkom sp. nov. (holotype, FMNH 240714) to its hypothesized sister species, P. kityoi (paratype, FMNH 223211); A: upper dentition of P. mbamminkom sp. nov., B: upper dentition of P. kityoi, C: lower dentition of P. mbamminkom sp. nov., and D: lower dentition of P. kityoi. Scale bar ¼ 1 mm.

Figure 10. Dorsal view of the body of the holotype of Pseudoromicia mbamminkom sp.nov. The frosted look is an effect of the lighting: the coloration is homogeneous.

Figure 11. Ventral view of the body of the holotype of Pseudoromicia mbamminkom sp. nov.

Figure 12. Pinna and tragus of the holotype of Pseudoromicia mbamminkom sp. nov.

Figure 13. Holotype of Pseudoromicia mbamminkom sp. nov.: detail of the uropatagium with keeled calcar and plagiopatagium attached at the metatarsals.

Figure 14. Map of the type localities of Pseudoromicia species. Species marked with an asterisk ($) are part of the white-winged group. Map created using ArcGIS software by Esri (2020); basemap created by subsetting ESRI’s RESOLVE Ecoregions dataset (2017) containing 846 terrestrial ecoregions grouped into 14 biomes.

Figures 3 and 4. (3 [top]) Graphical results of the Principal Components Analysis based on log10–transformed variables, computed from the correlation matrix, for all specimens examined with all the mensural characters available (66 of 77 specimens with all the following characters: GLS, CIL, MPW, POB, BB, MTRL, C–C, M3–M3, DENL, and MAND) (3). Only the first two Principal Components are significant: PC1 accounts for 72.45% of the variation; PC2, 11.04%. (4 [bottom]) Graphical results of the Principal Components Analysis based on log10–transformed variables, computed from the correlation matrix, for specimens examined for which taxonomic identity had been established previously using sequence data (Monadjem et al. 2021a, b; this work) with all the mensural characters available (23 of 26 specimens with the following: GLS, CIL, MPW, POB, BB, MTRL, C–C, M3–M3, DENL, and MAND). Only the first three Principal Components are deemed significant; PC1 accounts for 73.79% of the variation; PC2, 12.16%; PC3, 4.60%.