Hylomyscus mpungamachagorum, Kerbis Peterhans & Hutterer & Doty & Malekani & Moyer & Krásová & Bryja & Banasiak & Demos, 2020
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publication ID |
https://doi.org/10.20363/BZB-2020.69.1.055 |
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publication LSID |
lsid:zoobank.org:pub:1FD4D09C-D160-4159-A50D-20B6FBC7D9E9 |
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persistent identifier |
https://treatment.plazi.org/id/C54F87EA-FFAA-FFCE-6316-FBC2FE38FA51 |
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treatment provided by |
Felipe |
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scientific name |
Hylomyscus mpungamachagorum |
| status |
sp. nov. |
Hylomyscus mpungamachagorum sp. nov. Demos, Hutterer & Kerbis Peterhans
urn:lsid:zoobank.org:act:2831AD81-B8BF-41FC-82D3-35F2069C016A
Holotype. Field Museum of Natural History , Division of Mammals, FMNH 177889 About FMNH (field number WT Stanley 5988), collected by WT Stanley, 25 Aug 2003 (originally listed as Hylomyscus sp. ). The specimen, consisting of a study skin and skull with postcranial skeleton, is an adult scrotal male (testes 13 × 8 mm) with worn first upper mo- lar (stage IV of Verheyen & Bracke 1966). The basisphenoid-occipital suture is fused. External measurements were made in the field: TL 244, HB 99, TV 147 , HF 20, EL 19, Wt 20.5. The holotype was collected in a standard snap trap (Museum Special).
Type locality. Tanzania, Kigoma Region, Kigoma District, Mahale Mountains, Mahale National Park 2100 m, 0.5 km NW Nkungwe Hill summit (29.77895° E, 6.10433° S) GoogleMaps .
Paratypes (n = 11). Tanzania, Mahale National Park , Mahale Mountains, Mahale National Park 2100 m, 0.5 km NW Nkungwe Hill summit (29.77895° E, 6.10433° S) GoogleMaps 178011, 177888, 177890–177892, 177911; Kabezi Riv- er, 1180 m, 193233 (29.8317° E, 6.1131° S) GoogleMaps ; Mahale National Park , Mfitwa Mt, 2440 m, 193234, 193218 (29.7939° E, 6.1317° S) GoogleMaps ; Mahale National Park , 0.5 km S of Pasagulu Hill, 1420 m (29.75353° E, 6.06618° S) GoogleMaps , 177886, 177887.
Diagnosis. A member of the H. anselli group with a short rostrum (nasals are 34.5% of ONL, Table 4), posterior palatal foramen located posteriorly (at the first lamina of M 2, Figs 8c View Fig , 12c View Fig ), and maxillo-palatal suture located posteriorly – either between second and third lamina of M 1 or at level of third lamina of M 1 ( Figs 8c View Fig , 12c View Fig ). Zygomatic plate slightly sinuous in lateral view. Sub-squamosal fenestra moderate (ca. 25–30% of postglenoid foramen; i.e., Carleton & Stanley 2005: fig. 6; Fig. 12e View Fig ). Incisive foramina penetrate the alveoli of the upper tooth row ( Figs 8c View Fig , 12c View Fig ). Frontoparietal suture shallowly U-shaped.
Comparisons. A mid-sized member of the Hylomyscus anselli group with an upper molar crown length ca. 3.8 mm, needing comparison only with H. kerbispeterhansi and H. arcimontensis . It is unique among these three in the location of its posterior palatal foramina, located at the beginning of the second molar ( Figs 8c View Fig , 12c View Fig ); in H. kerbispeterhansi it is located at the third lamina of the M 1, while in H. arcimontensis it is located between M 1 and M 2. The morphometrics of H. mpungamachagorum align closely with H. arcimontensis ; indeed, it falls completely within its morphometric space ( Figs 1–2 View Fig View Fig ). Compared to H. kerbispeterhansi , the skull is smaller (CI 23.3 vs 24.7, Table 4) and with shorter nasals (LN 8.7 vs 9.45) and diastema (LD 6.95 vs. 7.82) ( Table 4).
Description. Size medium (mean HB = 98, CLM 3.74– 3.85, mean mass = 22 g). Mean tail length 41% longer than HB. Tail unicolor with ca. 15 annulations per cm. Belly hairs 6 mm, basal 3 mm slate grey, distal 3 mm light brown. Dorsal hairs 10 mm, basal 8 mm slate grey, apical 2 mm light brown. Dorsum of head same color as back. Upper lip with white hairs, dark grey roots. Vibrissae long, black, up to 35 mm in length. Pes dirty white in appearance due to white hairs overlaying darker skin. Manus white. Ears black, hairs inconspicuous. The hind foot possesses the standard murine complement of 6 pads (see Ibe et al. 2014: fig. 2 II for reference); there is a single accessory pad on each of the 1 st and 4 th interdigital pads; the first is large and well-integrated into the 1 st inter-digital pad, while the 4 th is smaller and distinct from the 4 th interdigital pad ( Fig. 9b View Fig ). There are seven fleshy palatal ridges: two are continuous and pre-dental, one is discontinuous and pre-dental, and the last four are discontinuous and inter-dental (as in Fig. 13 View Fig ).
Skull medium (mean ONL= 25.25 mm, mean CLM = 3.8 mm). Rostrum moderate (nasals 34.5% GLS). Upper incisors orthodont but slightly opisthodont in younger individuals. Incisive foramina just reach the M 1 alveoli. T3 on M 2 is tiny but distinct as in the other species described here. Braincase elongated. Hamular process of the squamosal long and thin, allowing for a moderate subsquamosal fenestra (ca. 25% of postglenoid foramen). Maxillo-palatal suture either falling between 2 nd and 3 rd lamina of M1 or at 3 rd lamina of the M1. Post palatal foramina small, lying level with 1 st lamina of M 2. Zygomatic plate narrow (mean = 2.3 mm) and slightly sinuous. Mesopterygoid fossa rounded at rostral end.
In comparison with other members of the H. anselli group, the following characters are relevant: 1) mammary formula 2+4, 2) upper incisors orthodont but younger individuals (wear stage III and IV, i.e., FMNH 177890– 1778892, 193218) slightly opisthodont, 3) T3 on M 1 is large, the anterior chevron more or less equal in size to T1 and T1 not as deflected far posteriorly as in H. stanleyi ( Fig. 7d View Fig ), 4) T9 on M 1 is distinct ( Fig. 7d View Fig ), 5) interorbital constriction has a weak shelf, 6) rostral length (LN/ ONL) is moderate at 34.5%, 7) incisive foramen meets the beginning of the M 1 alveoli (in the four younger individuals the incisive foramina penetrate the upper tooth row crowns), 8) the hamular strap is long and thin and the subsquamosal foramen is well developed but proportionately smaller than in the new Congolese species ( H. pygmaeus , H. thornesmithae ) described above ( Figs 12e View Fig ).
Unlike other species described herein, several skulls of this taxon show anomalous patterns of the palate including extra post palatal foramen (FMNH 177887, 177888, 193218) and interrupted incisive foramina ( FMNH 177886 About FMNH , 177887 About FMNH ) . One specimen ( FMNH 193234 About FMNH ) also displays a white tail tip.
Distribution. Known only from Mahale National Park, 1180–2440 m, western Tanzania.
Reproduction. Of the specimens collected, there were 7 males and 5 females. The reproductive condition of 4 females was inspected: females collected on Aug 25 & 28, 2005 had no embryos ( FMNH 177888 About FMNH , 177890 About FMNH ) but the former was lactating. Two others were in the early stages of pregnancy: FMNH 178011 About FMNH , collected on 25 Aug., 2003 ( CR = 5 mm) and FMNH 193233 About FMNH , collect- ed 9 Nov., 2005 ( CR = 7 mm) .
Habitat. The Mahale Peninsula is predominately covered with Brachystegia (Miombo) woodland, but higher elevations on the Mahale Ridge are covered in montane grasslands and forest ( Itani 1990). Forest is also found on the western and southwestern slopes from the ridge at 2400 m down to lowland forests at 780 m on the shore of Lake Tanganyika. The montane forest vegetation is an outlier of the Albertine Rift forests. Over 1,170 plant species, of which 39 are Albertine Rift endemics, have been recorded at Mahale ( Nishida & Uehara 1981; Nishida 1990; Plumptre et al. 2007).
One specimen was collected in riverine forest along the Kabezi River. This river and other smaller tributaries flowing down the Mahale and Kabezi ridges are lined with riverine forest surrounded by tall Miombo woodland with stands of solid-stemmed bamboo, Oxytenanthera abyssinica . Higher up on the Mahale Ridge, the Miombo gives way to tall montane grassland dominated by Hyparrhenia spp. , Themeda triandra , and Festuca sp. , with scattered Protea gauguedi , Erythrina abyssinica , Cussonia arborea and isolated Parinari curatellifolia . The riverine forest canopy reaches 30 m in places and is dominated by Newtonia buchannanii , Parinari excelsa , Bridelia micrantha , and Spathodea campanulata , with occasional Tabernaemontana stapfiana, Ficus sur, Ficus thonningii, Zanha golungensis, Prunus africana , and Myrianthus holstii . The understory is dominated by woody shrubs and Aframomum alboviolaceum ( Plumptre et al. 2003; Moyer 2006).
Two specimens originated in the Mfitwa Forest, on the SE side of the Mfitwa Peak (6°7’54” S, 29°47’38” S, 2440 m) which is surrounded by extensive areas of species-rich montane grasslands. The dominant species included Festuca sp. , Themeda triandra , and Hyparrhenia rufa . Mature parts of Mfitwa forest in sheltered val- leys reach a canopy height of 30 m. Dominate species include: Polyscias fulva , Parinari curatellifolia , Agaurista salicifolia, Croton megalobostrys, Croton sylvaticus , Bersama abyssinica , Trichilia emetica, Ficus thonningii, Myrianthus arboreaus , Maesa lanceolata , and Syzygium caminnii . The diverse forest understory is dominated by Olyra latifolia, Dracaena laxissima, Mondia whitei , Renealmia engleri, Psychotria sp., dense stands of bracken fern, Pteridium aquilinum , in light gaps and at the forest edge. Large areas of the forest are covered in nearly impenetrable monodominant stands of montane bamboo, Oldeania alpina , with very few other species penetrating this heavily shaded zone. Occasionally a forest tree emerges through the canopy in such stands; these areas are likely to be secondary, and at least some of them were under cultivation in the past ( Itani 1990).
Etymology. The species is named for Noah E. Mpunga and Sophy J. Machaga, who run the Southern Highlands Conservation Program for the Wildlife Conservation Society. These leading conservationists have dedicated the last 20 years to helping describe, advocate for, and protect some of Tanzania’s most threatened and iconic species. We recommend “Mahale wood mouse” as an English common name.
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Museo Nacional de Costa Rica |
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