Apomys (Megapomys) veluzi, Heaney & Balete & Duya & Duya & Kyriazis & Rickart & Steppan & Rowsey, 2025

Heaney, Lawrence R., Balete, Danilo S., Duya, Mariano Roy M., Duya, Melizar V., Kyriazis, Christopher C., Rickart, Eric A., Steppan, Scott J. & Rowsey, Dakota M., 2025, Three new species of Philippine forest mice (Apomys, Muridae, Mammalia), members of a clade endemic to Mindoro Island, Zootaxa 5647 (1), pp. 1-26 : 18-19

Apomys (Megapomys) veluzi new species lsid:zoobank.org:act: 4C772962-EDB9-48E6-A6BD-F74D9024C968

Figures 2B , 4 , and 5B; Tables 1 and 4

Holotype. Originally cataloged as FMNH 222928 ; to be transferred to PNM where it has been assigned catalog number PNM 9665 .Adult male captured on 7 February 2014, field number D. S. Balete 10262. Fresh tissue removed from thigh and placed in 95% ethanol. The rest of the specimen was preserved in formalin, then transferred to 75% ethanol; skull ( Fig. 5B ) removed and cleaned using dermestid beetles and a weak ammonia solution. All parts in good condition.

Type Locality. Philippines: Mindoro Island : Occidental Mindoro Province: Abra de Ilog Municipality: 0.65 km N, 2.1 km E Mt. Abra de Ilog peak, elevation 710 m; 13.40867 o N, 120.61901 o E ( Fig. 1 ) .

Measurements. Tables 1 and 4.

Specimens examined (n = 25). Abra de Ilog Municipality: 0.65 km N, 2.1 km E Mt. Abra de Ilog peak, elevation 710 m ( FMNH 222928–222936 ); 0.15 km N, 2.0 km E Mt . Abra de Ilog peak, elevation 850 m (222937–222946); 0.95 km N, 1.9 km E Mt. Abra de Ilog peak, elevation 1140 m (222947–222950); 1.55 km N, 2.15 km E Mt. Abra de Ilog peak, elevation 1325 m ( FMNH 222951 , 222952 ) .

Etymology. We take great pleasure in naming this species in honor of Maria Josefa “Sweepea” Veluz (1968– 2022), mammalogist at the National Museum of Natural History of the Philippines, in recognition of her life-time of contributions to field and museum studies and to public appreciation and enjoyment of the remarkable mammal fauna of the Philippines through development of exhibits at the National Museum.

Diagnosis and Description. A member of the genus Apomys , with diagnostic features as listed above. A small mouse (HB x̄ = 129.1 mm, BOL x̄ = 31.79 mm). Fur is soft, with dorsal color a rich brown with ochraceous highlights extending to top of head that darkens slightly but noticeably along the midline and between the eye and area supporting vibrissae, and paler orange-brown cheeks, producing a dark partial mask ( Fig. 2B ). Scattered dark guard hairs barely projecting above fur in lateral view; underfur slate gray. Vibrissae up to 55 mm long. Small area of pale sandy-orange hair behind ear, slightly longer than surrounding fur. Dorsal pelage becoming slightly paler laterally before an abrupt transition to ventral pelage that is pale cream in color, with a notable ochraceous wash at the tips, paler posteriorly over abdomen than over rib cage, with gray underfur. Fur below the jaw is nearly white. Ears long and conspicuous, LE/HB x̄ = 0.16 ( Table 1); skin on ears medium brown, paler toward base and at rim of ears, with microscopic hairs on both surfaces. Tail dorso-ventrally bicolored, medium brown dorsally, white ventrally (when clean); no specimens have a white tip on the tail. Tail is bare, relatively long (TV/HB x̄ = 1.19; Table 1), with no hairs readily visible except for having short, inconspicuous hairs toward tip. Forefeet with pale cream fur dorsally that extends from lower forearm to base of digits; ventral side is unpigmented. Hind feet similarly furred and colored, relatively long and narrow (HF/HB x̄ = 0.28). Claws on fore and hind feet curved, moderate in length.

The skull of A. veluzi shares the diagnostic features of the genus Apomys as listed above, but is one of the smaller species of the subgenus Megapomys (BOL x̄ = 31.79 mm), with unusually short incisive foramena, relatively low braincase height, and proportionately narrow zygomatic plate ( Table 4).

Comparisons. For comparison with A. gracilirostris , see above. Apomys veluzi differs externally from A. crinitus sp. nov. in that the latter is slightly smaller overall ( Tables 1 and 4); has dorsal fur that is slightly paler and brighter overall, with brighter orange highlights; both have a partial mask of dark hairs on the top and sides of head ( Figs. 2B and 2C ), but that of A. veluzi is more conspicuous. A. crinitus sp. nov. has conspicuous tufts of hair behind the ears, longer than nearby dorsal fur, pale cream in color; skin of ears pale brown, rather than medium brown on A. veluzi ; ventral fur also cream-colored but paler, with a less apparent ochraceous wash, becoming nearly white on throat and under rostrum. Mystacial vibrissae of A. veluzi up to 55 mm, those of A. crinitus sp. nov. up to 50 mm. The tail of Apomys veluzi is slightly darker dorsally, with similar length; slightly longer in absolute length of head and body, hind foot, and ear, but similar in relative length of tail, hind foot, and ear ( Table 1).

Compared to the skull of A.veluzi ( Fig. 5B ), that of A.crinitus sp. nov. ( Fig.6A ) is smaller in most measurements ( Table 4), but with zygomatic breadth, rostral depth, rostral length, and orbito-temporal length equal or slightly greater, and with incisive foramen usually longer, zygomatic plate broader and braincase height greater ( Table 4).

Relative to Apomys veluzi , A. minor sp. nov. is smaller (HB x̄ = 129 mm vs. 122 mm, TV x̄ = 151 mm vs. 140 mm, HF x̄ = 36.6 vs. 34.5 mm; BOL x̄ = 31.8 mm vs. 30.8 mm; Tables 1 and 4); has dorsal fur that is darker brown and less ochraceous; hair behind the ears that is the same length and color as nearby dorsal fur (tuft absent); fur on the top of the head that is the same color as over the torso, without a darkened “mask;” ventral pelage that is pale brown with distinct ochraceous wash, but often with a white blaze over the lower abdomen that is variable in length and width; tail dark brown dorsally, hairs barely visible, ventrally ranging from medium brown to white, proportionately longer in A. veluzi (TL/HB x̄ = 1.19 vs. 1.15; Table 1)

Skull of A. minor sp. nov. differs from A. veluzi in being smaller in most measurements, but with mastoid breadth, rostral depth, orbitotemporal length, upper molar toothrow length, palatal breadth, braincase height, and zygomatic plate nearly equal or slightly greater, and length of incisive foramen notably greater.

Distribution. Currently known only from Mt. Abra de Ilog, from 710 m to 1325 m (survey area 2 in Fig. 1 ). Our survey of the mammals of Mt. Calavite, a nearby peak at the northwestern tip of Mindoro (survey area 1), failed to produce specimens of this species or other Megapomys .

Ecology. We captured 29 A. veluzi along our transect of Mt. Abra de Ilog, which reaches a maximum of 1421 m. All individuals were captured at night on the ground in traps baited with either live earthworms or thin slices of coconut fried and coated with peanut butter. Numbers per 100 trap-nights at our four sampling areas were 0.92 (9 at 710 m), 1.32 (11 at 850 m), 0.75 (6 at 1140 m), and 0.34 (3 at 1325 m). This was the most numerous species captured along our transect, with Apomys microdon and Anonymomys mindorensis as the next most common native species; Crocidura grayi , Apomys musculus , Chrotomys mindorensis , Rattus everetti gala , and Rattus mindorensis were also present along the transect, as were the exotic pest rats Rattus exulans and R. tanezumi . At 710 m and 850 m, we trapped A. veluzi in a narrow strip of disturbed lowland forest along the steep slopes next to the Pambuhan River, framed by extensive anthropogenic grassland on the upper slopes. The tallest trees were ca. 25 to 40 m, with Ficus , Shorea , Terminalia , and Mangifera among the most common. Leaf litter and humus were scarce. At 1140 and 1325 m, we trapped this species in transitional lowland-montane forest with trees reaching 15-30 m in height; Ficus and Shorea were present, but Elaeocarpus , Lithocarpus , and Syzygium were more common. Leaf litter and humus were each usually 1–3 cm thick at 1140 m, and 3–6 cm at 1325 m. Understory and ground-cover plants were abundant at all sampling areas.

Female A. veluzi have two pairs of inguinal mammae. Eight individuals weighing 25–58 g were noted in the field as having small, inconspicuous mammae; one of these weighing 54 g had no uterine scars or embryos. Four females weighing 57–66 g had larger, lightly pigmented mammae. Six males weighing from 57 g to 65 g had scrotal testes measuring 6 x 4 to 7 x 5 mm. Those of males weighing 54 g and 52 g had testes 7 x 4 and 5 x 4 mm, respectively, and two that weighed 51 g had abdominal testes of 4 x 3 mm.

Figures

FIGURE 1. A, Map of Mindoro Island showing topographic features and the locations of areas intensively surveyed by the authors. 1 = Mt. Calavite; 2 = Mt.Abra de Ilog; 3 = Mt. Halcon; 4 = Mt. Tallulah; 5 = Mt. Mangibok; 6 = Mt.Wood; 7 = Barangay Morente; 8 = Mt. Masulong; 9 = Sta. Teresa Hill and Mt.Alibug; 10 = Ilin Island. Apomys gracilirostris were captured in area 3; A. veluzi sp. nov. in area 2; A. crinitus sp. nov. in areas 4 and 5; and A. minor sp. nov. in areas 6 and 9. Members of the subgenus Megapomys were not detected in areas 1, 7, 8, and 10. B, Elevational ranges of the four species of Megapomys on Mindoro based on specimens reported here. For each species, black circles indicate elevations at which the given species was documented; open circles are elevations along the same transects where the relevant species was not documented; short horizontal lines indicate the maximum elevation along the given transect. For A. gracilirostris, open triangles indicate elevations at which Ruedas (1995) reported that species. Dark vertical lines connect localities along a single transect where the given species was documented.

FIGURE 2. Drawings of four species of Apomys (Megapomys) from Mindoro. A = A. gracilirostris (from study area 3 in Fig. 1), B = A. veluzi sp. nov. (from study area 2 in Fig. 1), C = A. crinitus sp. nov. (from study areas 4 and 5 in Fig. 1), D = A. minor sp. nov. (from study areas 6 and 9 in Fig. 1).

FIGURE 4. Results of principal components analysis of 18 craniodental measurements (Table 3) of 19 adult Apomys (Megapomys) from Mindoro. Loadings and eigenvalues are shown in Table 5.

FIGURE 5. Photographs of the skulls of A Apomys gracilirostris (FMNH 222320) and B Apomys veluzi sp. nov. (holotype, FMNH 222928).

FIGURE 6. Photographs of the skulls of A Apomys crinitus sp. nov. (holotype, FMNH 222954) and B Apomys minor sp. nov. (holotype, FMNH 228798).