Crocidura mediocris, Esselstyn & Achmadi & Handika & Swanson & Giarla & Rowe, 2021

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 : 63-66

Crocidura mediocris , new species

LSID: urn:lsid:zoobank.org:act:1587FDA2-B27F-47C4-95DF-E44A1081CCA4

HOLOTYPE: MZB 43007 (= FMNH 210603 ), an adult female collected by J.A. Esselstyn on 22 October 2010. The specimen consists of a dried skin, cleaned skull and skeleton, and tissue samples. External measurements from the holotype are: 102 mm × 41 mm × 11 mm × 7 mm = 3.7 g. The voucher specimen and a tissue sample will be permanently curated at MZB, with an additional tissue sample retained by FMNH.

TYPE LOCALITY: Indonesia, Sulawesi Selatan, Luwu Utara, Sukamaju, Mt. Balease ; 2.50002° S, 120.48726° E, 862 m elevation.

ETYMOLOGY: Mediocris is Latin for “average,” applied in recognition that this is a species of shrew with no striking phenotypic traits worthy of hanging a descriptive name on.

GEOGRAPHIC DISTRIBUTION: This species is found across the southern and western portions of the west-central area of endemism (Mts. Torompupu and Balease, Central Sulawesi Province; Salu Tiwo, West Sulawesi Province; and Mt. Latimojong, South Sulawesi Province) and in the south-east area of endemism (Mt. Mekongga, Southeast Sulawesi Province; fig. 25 ). We found this species from approximately 200 to 1900 m elevation ( fig. 13 ). Although the species was present at Salu Tiwo (ca. 200 m), we did not find it at higher elevations on Mt. Gandang Dewata ( table 3 ).

DIAGNOSIS: Crocidura mediocris is another small shrew ( tables 2 , 8 ), with a delicate build and dark gray to medium brown pelage that is only slightly paler on the venter. The tail is shorter than head-and-body length and moderately dorsoventrally bicolored. The feet are somewhat paler than the pelage, more so around the digits ( fig. 29B ). The pelage covers the body completely, but individual hairs are short (2–3 mm at middorsum). Mystacial vibrissae are short relative to body size, and unpigmented along most of their length. The tail is covered in moderately dense bristles along the proximal two-thirds of its length and a relatively high density of short, dark, applied hairs along its entire length ( fig. 29B ). The dorsal surfaces of the digits and, in some specimens, the feet are light brown. The plantar and palmar surfaces are generally dark, but the ventral sides of the digits are white ( fig. 29B ). As is typical, more pigment is present on the posterior and lateral portions of the palmar and plantar surfaces. The skull is small and delicate, with a relatively robust dentition ( fig. 31B ). The braincase is somewhat narrow and the interobital region is narrow relative to skull length ( fig. 10 ). The maxillary process is modest and the maxillary bridge is narrow ( fig. 31B ). The lambdoidal ridge is prominent for such a small species.

COMPARISONS: Crocidura mediocris is one of the smallest species on Sulawesi, easily distinguished on body size alone from all species outside the Small-Bodied Group ( fig. 10 ). Crocidura normalis is the smallest member of the Ordinary Group and may be closely related to C. mediocris and C. parva , also of the Small-Bodied Group ( figs. 5 , 7 ). Compared to C. normalis , C. mediocris is smaller, paler colored, and has a shorter tail ( fig. 10 ; table 2 ). Among the Small-Bodied species, C. mediocris has the shortest average head-and-body length. Its tail is also short, and relative tail length is comparable to C. baletei , greater than in C. levicula , C. tenebrosa , and C. parva , and only slightly less than in C. lea ( fig. 9 ). In color, the feet of C. mediocris are darker than those of C. lea . Aside from the relative tail-length differences, C. mediocris is similar to C. levicula in overall proportions but differs in having a longer and slightly narrower skull ( table 8 ), paler pelage and feet, more rounded hypothenar on the hind foot ( fig. 29 ), and on average, fewer tail bristles. Crocidura mediocris is also paler than both C. tenebrosa ( fig. 27C ) and C. parva ( fig. 29C ). In cranial proportions, C. mediocris has a greater average condyloincisive length than C. levicula and C. parva , but is comparable in this regard to C. lea , C. baletei , and C. tenebrosa ( table 8 ). The length of the rostrum, relative to skull length (RL/CIL), is greater on average than in C. lea , C. levicula , and C. parva ( fig. 10 ). The relative breadth of the braincase (BB/ CIL) is greater than in C. lea and slightly more than in C. parva , but less than in the other Small- Bodied species. In morphometric space, a bivariate plot of condyloincisive length versus braincase breadth shows that C. mediocris occupies a widthto-length ratio between the narrow C. lea and C. parva and the wide C. levicula , C. baletei , and C. tenebrosa ( fig. 26A ). A PCA of cranial dimensions shows that specimens of C. mediocris occupy moderately distinct morphometric space, overlapping primarily with individuals of C. lea and C. parva ( fig. 26A ).

COMMENTS: Crocidura mediocris is closely related to C. parva . See the C. parva account for a discussion of phylogenetic relationships between these two phenotypically similar species. For coalescent species delimitation results, see the C. normalis (Ordinary Group) and C. parva accounts below.

SPECIMENS EXAMINED: Mt. Balease ( FMNH 210563–210575 , 210602 , 210604–210606 ; MZB 43007 ), Mt. Gandang Dewata ( FMNH 218617 , 218619 , 218620 , 218622–218638 , 218640– 218642 , 218644–218649 ), Mt. Latimojong ( MVZ 237574 ) , Mt. Mekongga ( MWFB 8092 , 8104 , 8121 , 8131–8136 , 8140–8142 , 8144 , 8145 , 8148 , 8149 , 8152 , 8153 , 13508 , 13510 , 13513 , 13514 ), Salu Tiwo ( FMNH 218614–218616 , 218618 , 218621 , 218639 , 218643 , 218650 , 218651 ), Mt. Torompupu ( LSUMZ 39452–39457 , 39555 ; MVZ 238109–238114 ; NMV C40246 , C40251 , C40253 , C40274 , C40278 , Z62199 ).

Figures

FIG. 25. Map of Sulawesi showing localities sampled for shrews. Colored areas enclose localities with known records of members of the Small-Bodied Group of Sulawesi Crocidura.

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. 29. Images showing the ventral surface of the left hind foot and dorsal surfaces of the tail base (approximately 1 cm from rump) and tail tip from the three members of the Small-Bodied Group that are not from the northern peninsula: A, Crocidura levicula, FMNH 213271; B, C. mediocris, FMNH 210566; and C, C. parva, MVZ 237583. Where two scale bars are present within a panel, the upper applies to the foot and the lower to the tail.

FIG. 31. Images showing dorsal, ventral, and lateral views of the skull and lateral and occlusal views of the dentary of the three members of the Small- Bodied Group that are not from the northern peninsula: A, Crocidura levicula, FMNH 213362; B, C. mediocris, FMNH 210603; and C, C. parva, MVZ 237577.

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. 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.

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. 27. 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 the three members of the Small-Bodied Group that are from the northern peninsula: A, Crocidura baletei, LSUMZ 36959 (right hind foot); B, C. lea, LSUMZ 38254 (left hind foot); and C, C. tenebrosa, LSUMZ 39268 (right hind foot). Scale bars represent 5 mm. Within each panel, the upper bar applies to the foot and the lower bar corresponds to both tail images.

FIG. 26. Bivariate plots showing A, variation in the condyloincisive length and braincase breadth and B, the first two axes from a principal components analysis of 12 cranial measurements among all members of the Small-Bodied Group. Loadings and variance explained are given in table 9.