Crocidura musseri Ruedi, 1995

Esselstyn, Jacob A., Achmadi, Anang S., Handika, Heru, Swanson, Mark T., Giarla, Thomas C. & Rowe, Kevin C., 2021, Fourteen New, Endemic Species Of Shrew (Genus Crocidura) From Sulawesi Reveal A Spectacular Island Radiation, Bulletin of the American Museum of Natural History 2021 (454), pp. 1-109 : 76-78

Crocidura musseri Ruedi, 1995

Crocidura musseri Ruedi, 1995: 254 . Original description.

HOLOTYPE: MZB 16791 (= IZEA 4397 ), an adult female caught 18 August 1991. Measurements from the holotype are TC (head-andbody length): 66 mm × Q (tail length): 57 mm × PP (hind-foot length): 13.5 mm = Pds (weight): 6.5 g. TYPE LOCALITY: Mt. Rorekatimbo, Central Sulawesi, at 1° 16’ S, 120° 15’ E, 2230 m elevation.

GEOGRAPHIC DISTRIBUTION: Apparently restricted to high elevation areas (> 1800 m) in the northern portions of the west-central area of endemism east of the Palu-Koro Fault in Central Sulawesi Province ( figs. 13 , 39 ; table 3 ). Ruedi (1995) reported specimens of this species from only the type locality on Mt. Rorekatimbo. We collected specimens that match Ruedi’s description and are mitochondrially identical (based on cytochrome b sequences from Ruedi et al., 1998) from the same mountain, at three nearby sites (1.3093° S, 120.3092 °E, 2020 m; 1.2926° S, 120.3064° E, 2180 m; 1.2884° S, 120.3104° E, 2250 m). Musser collected additional specimens from 1800–2300 m elevation on the neighboring Mt. Nokilalaki (ca. 15 km W of Mt. Rorekatimbo).

EMENDED DIAGNOSIS: A medium-sized shrew ( tables 2 , 14 ) with a thick, dark brown pelage that is only slightly paler on the venter. Foot, ear, tail, and rhinarium color closely match the pelage. Tail

length is shorter than head-and-body length. The tail has inconspicuous applied hairs that are visible with the naked eye only on the distal third of tail length and sparse bristle hairs spread from the tail base to at least its midpoint ( fig. 36A ). The braincase is notably inflated, with great width, giving an overall wedge-shaped appearance when viewed from the dorsal aspect ( fig. 37A ). The squamosal-parietal suture is often open, leaving a tear-drop-shaped opening anteriorly, directly below the anterior opening of the sinus canal (sensu McDowell, 1958).

COMPARISONS: Crocidura musseri is smaller than members of the Elongata Subgroup and all Rhoditis Group members except C. pallida . It is larger than all members of the Small-Bodied Group. Within the Ordinary Group, C. musseri is smaller than C. nigripes , slightly larger than the sympatric C. normalis , and comparable to C. ordinaria and C. solita . Relative to head-and-body length, C. musseri has a shorter tail than all members of the Long-Tailed and Rhoditis groups, C. nigripes , and the sympatric C. solita . The pelage of C. musseri is thicker than that of any other shrew species we recognize from Sulawesi, except C. caudicrassa . Overall, the color of C. musseri is substantially darker than specimens from the Long-Tailed and Rhoditis groups, C. lea , and C. mediocris . Within the Ordinary Group, C. musseri is slightly darker than C. solita and C. normalis . Relative to skull length, skull width at both the braincase and interorbital region is greater than most other spe- cies, including all members of the Ordinary Group ( figs. 10 , 37 ). The unusual width of the skull ( table 14 ) gives C. musseri a more wedge-shaped appearance than any other species when viewed from the dorsal aspect ( fig. 37A ). Crocidura nigripes has a more angular braincase, a more robust dentition, and a much narrower relative interorbital region (IOW/CIL). Relative rostral length (RL/CIL) in C. musseri is less than in C. nigripes , but greater than in C. normalis ( fig. 10 ). Crocidura musseri is distinguished from all sympatric shrews by a combination of its short tail length, thick and dark pelage, and wide, wedge-shaped skull with small teeth ( figs. 9 , 36 , 40 ).

COMMENTS: Our description of Crocidura musseri is based primarily on the series of specimens we collected in 2011 very near the type locality. This series matches the holotype (MZB 16791) and the description of Ruedi (1995). Cytochrome b sequences from our series are identical to one from a paratype (IZEA 4403; Ruedi et al., 1998). None of our phylogenetic analyses supported a close relationship of C. musseri to any other species. Our mitogenome result placed C. musseri as sister to all other members of Sulawesi’s endemic radiation with some support ( fig. 5 ), while our UCE species tree placed it as sister to C. microelongata and C. pallida , but without statistical support ( fig. 7 ).

SPECIMENS EXAMINED: Mt. Nokilalaki ( AMNH 223495 , 225516 , 225517 , 225521 , 225525–225527 , 225530 , 225531 ), Mt. Rorekatimbo ( FMNH 213249–213251 , 213253–213256 , 213258–213269 , 213442 , 213443 ; MZB 16791 ).

Figures

FIG. 13. Elevational records of all species of Crocidura known from Sulawesi. Each point represents a specimen. For specimens associated with a minimum and maximum elevation, we used the center of the given elevational range. Sample sizes are given above the x-axis. Species are grouped according to the species groups used in the text (Thick = Thick-Tailed Group).

FIG. 39. Map of Sulawesi showing localities sampled for shrews. Colored areas enclose localities with known records of members of the Ordinary Group. To maintain clarity of presentation, the widespread Crocidura nigripes is not included.

FIG. 36. Images showing the ventral surface of the right hind foot and dorsal surface of the tail base (approximately 1 cm from rump) and tail tip from two darkly pigmented members of the Ordinary Group: A, Crocidura musseri, FMNH 213267; and B, C. nigripes, LSUMZ 37018. Scale bars apply to all images in panel A and to foot (upper) and tail (lower) in panel B.

FIG. 37. Images showing dorsal, ventral, and lateral views of the skull and lateral and occlusal views of the dentary of two darkly pigmented members of the Ordinary Group: A, Crocidura musseri, FMNH 213255; and B, C. nigripes, FMNH 210611.

FIG. 10. Box plots of relative skull measures showing braincase breadth (BB), interorbital width (IOW), and rostral length (RL) divided by condyloincisive length (CIL) and BB divided by IOW for all species of Sulawesi shrew. Plots show the median, 1st and 3rd quartiles, the maximum value within 1.5 × interquartile range (distance between 1st and 3rd quartiles; IQR), the minimum value within 1.5 × IQR, and outliers (black circles). Sample sizes are shown along the x-axis. Species are ordered according to the species groups used in the text (Thick = Thick-Tailed Group).

FIG. 9. Box plots showing variation in external measurements from all species of Sulawesi shrew. Plots show the median, 1st and 3rd quartiles, the maximum value within 1.5 × interquartile range (distance between 1st and 3rd quartiles; IQR), the minimum value within 1.5 × IQR, and outliers (black circles). Sample sizes are shown along the x-axis. Species are grouped according to the species groups used in the text (Thick = Thick- Tailed Group). All measurements in mm. HBL = head-and-body length.

FIG. 40. Images showing the ventral surface of the hind foot and dorsal surfaces of the tail base (approximately 1 cm from rump) and tail tip from three members of the Ordinary Group: A, Crocidura normalis, FMNH 213174 (left hind foot); B, C. ordinaria, FMNH 218726 (right hind foot); and C, C. solita, FMNH 213015 (left hind foot). Upper scale bar for foot, lower bar corresponds to both tail images.

FIG. 5. Maximum likelihood estimate of the mitochondrial gene tree derived from an analysis of 14,007 characters (representing protein-coding and rRNA genes) from 83 samples. Bootstrap support values <95 are shown at nodes. Tips are labeled with the species, locality, and voucher number.

FIG. 7. Estimated species tree from analysis of 3940 ultraconserved element loci in ASTRAL. Samples from Sulawesi are labeled with the species name, locality, and catalog number. Asterisks indicate type specimens from Miller and Hollister (1921). Local posterior probabilities <0.95 are shown. Tip branch lengths are arbitrary.

Tables

TABLE 14 Descriptive Statisticsa for Craniodental Measurements (mm) for Species of the Ordinary Group of Sulawesi Crocidura

	C. musseri	C. nigripes	C. normalis	C. ordinaria	C. solita
Condyloincisive length	20.13 ± 0.446 (19.17–20.78) 17	22.47 ± 0.733 (20.91–24.32) 80	18.73 ± 0.276 (18.29–19.66) 27	20.38 ± 0.491 (19.47–21.59) 15	20.13 ± 0.584 (19.25–21.55) 43
Braincase breadth	9.74 ± 0.233 (9.42–10.26) 18	9.94 ± 0.315 (9.32–10.78) 77	8.61 ± 0.168 (8.45–9.06) 27	9.79 ± 0.178 (9.48–10.06) 15	9.51 ± 0.263 (8.8–10.12) 43
Interorbital width	4.91 ± 0.164 (4.61–5.2) 18	4.71 ± 0.196 (4.3–5.08) 85	4.3 ± 0.114 (4.11–4.58) 28	4.86 ± 0.137 (4.65–5.12) 16	4.68 ± 0.167 (4.36–5.06) 43
Rostral length	8.16 ± 0.205 (7.76–8.39) 17	9.31 ± 0.337 (8.45–10.09) 86	7.36 ± 0.163 (7.09–7.75) 28	8.25 ± 0.285 (7.77–8.95) 16	8.15 ± 0.363 (7.2–9.17) 43
Postpalatal width	3.84 ± 0.12 (3.59–4.03) 18	4.02 ± 0.156 (3.7–4.38) 85	3.34 ± 0.106 (3.15–3.68) 28	3.96 ± 0.18 (3.7–4.36) 16	3.88 ± 0.147 (3.57–4.22) 43
Rostral width	2.65 ± 0.147 (2.46–3.03) 17	3.02 ± 0.17 (2.62–3.58) 86	2.47 ± 0.172 (2.08–2.71) 28	2.96 ± 0.139 (2.73–3.18) 16	2.73 ± 0.198 (2.31–3.2) 43
Postpalatal length	8.89 ± 0.222 (8.4–9.23) 18	9.79 ± 0.366 (8.9–10.54) 80	8.41 ± 0.231 (8.08–9.03) 27	9.1 ± 0.297 (8.7–9.87) 15	8.89 ± 0.304 (8.41–9.51) 44
Condyle to gle- noid fossa	7.93 ± 0.186 (7.52–8.24) 18	8.37 ± 0.281 (7.78–8.9) 80	7.72 ± 0.134 (7.47–8.01) 27	8.09 ± 0.194 (7.77–8.43) 15	7.93 ± 0.224 (7.35–8.49) 43
Upper toothrow length	8.84 ± 0.229 (8.35–9.19) 17	10.2 ± 0.359 (9.24–11.02) 86	8.07 ± 0.211 (7.69–8.7) 28	9.04 ± 0.254 (8.63–9.68) 16	8.91 ± 0.327 (8.07–9.89) 43
P4 to M3 length	5.08 ± 0.182 (4.7–5.34) 18	5.82 ± 0.238 (5.17–6.24) 86	4.49 ± 0.163 (4.23–5.02) 28	5.24 ± 0.167 (4.99–5.62) 16	5.11 ± 0.195 (4.72–5.67) 43
M2 to M2 labial width	5.86 ± 0.238 (5.44–6.16) 17	6.84 ± 0.253 (6.37–7.52) 86	5.12 ± 0.152 (4.85–5.63) 28	6.08 ± 0.286 (5.69–6.77) 16	5.9 ± 0.217 (5.53–6.61) 43
Palatal width	2.52 ± 0.085 (2.36–2.64) 18	2.74 ± 0.134 (2.45–3.19) 85	2.25 ± 0.096 (2.01–2.43) 28	2.49 ± 0.118 (2.31–2.8) 16	2.46 ± 0.105 (2.24–2.71) 43

a The sample mean ± one standard deviation, the observed range in parentheses, and the sample size.