Three small species of shrews (Soricidae) from the Salonga National Park, Democratic Republic of the Congo, representing two new taxa and a new record

3.1 Crocidura salonga Hutterer, sp. nov.

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Holotype: ZFMK 2023.0469, specimen preserved in 60 % ethanol, skull extracted, sex unknown; field number BINCO_DRC_22_0705a, collected by Merlijn Jocque on 12 December 2022 (Figure 3A–C).

Figure 3:

Dorsal, ventral, and lateral views of the skull of (A, B, C) the holotype of C. salonga sp. nov. (ZFMK 2023.0469).

Type locality: Democratic Republic of Congo, Salonga NP, lowland camp, 01°39′57.5″S, 20°31′58.1″E, 371 m.

Etymology: Named for the Salonga NP. The name is taken as a noun in apposition.

Diagnosis: A small, long-tailed species of Crocidura; tail 151 % of head and body length, no long hairs are present over its entire length. Skull small, slender, with a high-domed braincase. CIL 18.63 mm, UTR 8.07 mm.

Description: Small shrew with a long tail free of longer bristles over its entire length (Figure 2). Hindfeet short. Body hairs short (3 mm) at dorsum and 2 mm at ventrum. Colour of hairs at both dorsum and ventrum dark brown. Fore-, hindfeet, and tail covered with very short, light brown hairs. Ears large, almost naked. Skull slender, short for the dolichura group, interorbital region long (16.25 % of CIL), lateral margins of interorbital region almost parallel (Figure 3), front part of skull long and slender (41.25 % of CIL), braincase round (42.5 % of CIL) in dorsal view and slightly domed in lateral view. Front part of upper incisor long, tip in one line with tip of first unicuspid and tip of fourth premolar.

Measurements of the holotype: HB 55 mm, T 83 mm (TB 0 %), HF 12 mm, E 8 mm. CIL 18.63 mm, PL 8.0 mm, GW 8.12 mm, BW 5.43 mm, IO 3.83 mm, PGL 6.03 mm, UTR 8.07 mm, LTR 7.49 mm, COR 4.38 mm.

Comparative measurements: Crocidura dolichura Peters, 1876 (UA 1846; Kikwit, southern DRC): HB 61 mm, T 65 mm (TB 0 %), HF 13.6 mm, E 10 mm. CIL 19.84 mm, PL 8.14 mm, GW 8.50 mm, BW 6.15 mm, IO 4.36 mm, PGL 6.25 mm, UTR 8.70 mm, LTR 8.05 mm, COR 4.53 mm. The holotype of C. dolichura (ZMB 5037; Turni et al. 2007) was figured by Brosset et al. (1965). Crocidura polia Hollister, 1916 (holotype AMNH 48566; Hollister 1916): HB 58 mm, T 72 mm (a few scattered longer bristle-hairs on basal third of tail; white tail brush), HF 13 mm, E 9 mm. CIL 18.2 mm, GW 8.2 mm, BW 5.2 mm, IO 3.8 mm, UTR 7.8 mm, LTR 7.3 mm. Crocidura crenata Brosset et al. 1965 (holotype MNHN-ZM-MO-1981-1989; paratype MNHN-ZM-MO-1981-485; Brosset et al. 1965): HB 71 mm, T 85 mm, HF 17 mm. CIL 19 mm, GW 7.7 mm, BW 5.1 mm, IO 4.0 mm, UTR 8.8 mm, LTR 8.0 mm.

Discussion: The new species resembles C. dolichura (Brosset et al. 1965; Burgin 2018; Peters 1876; Ray and Hutterer 2013; Turni et al. 2007), C. polia (Hollister 1916; Hutterer 2013), and C. crenata (Brosset et al. 1965; Hutterer and Schlitter 1996). However, its external and cranial measurements are different. The tails of C. dolichura and C. polia are shorter (72–75 mm). C. crenata has hindfoot lengths between 15 and 17 mm, and C. dolichura and C. polia between 12 and 13 mm. C. dolichura and C. crenata have long tails without any longer bristles, but C. polia has longer hairs at the basal part and a white brush at its terminal end of the tail. The skull of C. dolichura is longer (CIL 19.84 mm from Kikiwit, southern DRC), and has a larger upper (8.70 mm) and lower (8.05 mm) toothrow. See also Brosset et al. (1965; figs 2, 4, 6, 8) for the holotype of C. dolichura. The skull of C. polia is even smaller (CIL 18.2 mm, GW 8.2 mm); the skull of C. crenata is larger (CIL 19.0 mm, UTR 8.8 mm, LTR 8.0 mm) and has a very narrow and delicate dentition (Brosset et al. 1965).

C. dolichura and C. polia occur north of the Congo River (Burgin 2018), and C. crenata west (Brosset et al. 1965; Lunde 2007), north (Gryseels et al. 2020) and east of the Congo Basin (Van de Perre et al. 2019). It is probable that the new species occurs only in the inner Congo Basin, although a single specimen collected in the Misotshi-Kabogo highlands, eastern DRC, reported as C. dolichura (Kerbis Peterhans et al. 2013), had similar small skull dimensions.

Long-tailed species of Crocidura were usually caught in Africa in very low numbers, for example C. dolichura (one specimen; Peters 1876), C. polia (one; Hollister 1916), C. crenata (two; Brosset et al. 1965). These species may be generally rare or possibly live in habitats difficult to access (partly arboreal?) with the traps used. Our case of C. salonga sp. nov. is therefore no exception from the rule.

3.2 Crocidura binco Hutterer, sp. nov.

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Holotype: ZFMK 2023.0470 (BINCO_DRC_22_0705b), specimen preserved in 60 % ethanol, skull extracted, sex unknown; collected by Merlijn Jocque on 12–13 December 2022 (Figure 4A–C).

Figure 4:

Dorsal, ventral, and lateral views of the skull of (A, B, C) the holotype of C. binco sp. nov. (ZFMK 2023.0470).

Paratypes: ZFMK 2023.0471 – 2023.0475 (BINCO_DRC_22_0705e, 0689b, 0689c, 0743a, 0743b), BE_RMCA_Vert.2024.004.M.0004-5 (DRC_22_0629a, 0629b), Salonga NP, lowland camp, 371 m (01°39′57.5″S, 20°31′58.1″E), coll. Merlijn Jocque, 12–13 December 2022. BE_RMCA_Vert.2024.004.M.0004-8 (BINCO_DRC_22_0828, 0884a, 0884b); Salonga NP, highland camp, 505 m (02°17′15.6″S, 21°01′18.8″E), collected by M. Jocque, 3–6 December 2022.

Type locality: Democratic Republic of Congo, Salonga NP, lowland camp, 01°39′57.5″S, 20°31′58.1″E, 371 m.

Etymology: The species is named for the Biodiversity Inventory for Conservation (BINCO) which organized the work in the Salonga NP. The new name is a noun in apposition.

Diagnosis: Smaller Crocidura species with a middle-sized, partly bristled tail, short hindfeet, and a small skull (Figure 4).

Description: Small shrew (HB 57–62 mm) with a middle-sized tail (37–56 mm), with longer bristles over 15.8 % of its length (Figure 2). Hindfeet short (11–12.5 mm). Body hairs short (3 mm) at dorsum and ventrum. Colour of hairs at both dorsum and ventrum very dark brown. Fore-, hindfeet, tail and ears of almost the same dark colour. Ears large (7–10 mm) and dark. Skull small (CIL 18.52–19.8 mm) with a short snout (41.8 % of CIL), a short, strongly divergent interorbital region (13.9 % of CIL), and a large braincase (44.3 % of CIL, dorsal view), which is slightly domed in lateral view.

Measurements of type series: HB 59.1 mm; 57–62 mm; n = 11, T 51.5 mm; 37–56 mm; n = 11 (TB 15.8 %; 10.8–20.4 %; n = 11), HF 11.9 mm; 11–12.5 mm; n = 11, E 8 mm; 7–10 mm; n = 11. CIL 19.22 mm; 18.52–19.8 mm; n = 7, PL 7.97 mm; 7.38–8.33 mm; n = 8, GW 8.39 mm; 8.21–8.66 mm; n = 7, BW 6.01 mm; 5.67–6.27 mm; n = 8, IO 4.1 mm; 3.75–4.32 mm; n = 8, PGL 6.0; 5.52–6.39 mm; n = 7, UTR 8.35 mm; 8.1–9.04 mm; n = 8, LTR 7.72 mm; 7.22–8.09 mm; n = 8, COR 4.59 mm; 4.45–4.76 mm; n = 8.

Comparative measurements: Crocidura hildegardeae Thomas, 1904 (ZFMK 1968_503–504, 1968_506–508, Kivu, eastern DRC; SMNS 13420, 13422–13424, 13428–13430, Lwiro, eastern DRC; ZFMK 2003_821–823, Epulu, R-F. Okapis, DRC; UA 171, 1396, 1780, 2535, Kikwit, southern DRC): HB 66.7 mm; 54–80 mm; n = 16, T 50.1 mm; 34–77.8 mm; n = 16 (TB 56.6 %; 40–77.8 %; n = 14), HF 13 mm; 10.3–14 mm; n = 16, E 8.1 mm; 7–9.5 mm; n = 16. CIL 19.43 mm; 18.07–20.27 mm; n = 12, PL 7.98 mm; 7.23–8.31 mm; n = 16, GW 8.9 mm; 8.18–9.72 mm; n = 15, BW 6.32 mm; 5.55–7.24 mm; n = 16, IO 4.34 mm; 3.72–4.7 mm; n = 15, PGL 6.24 mm; 5.35–6.97 mm; n = 15, UTR 8.39 mm; 7.93–9.05 mm; n = 16, LTR 7.72 mm; 7.25–8.49 mm; n = 16, COR 4.64 mm; 4.10–5.32 mm; n = 16.

Comments: The species resembles C. hildegardeae but differs externally by a low pilosity of the tail of 15.8 % against 56.6 % (40–77.8 %; n = 14) in hildegardeae, by slightly shorter hindfeet (11–12.5 against 10.3–14 mm), by a slightly shorter tail (37–56 against 40–77.8 mm) (Stanley 2013; Thomas 1904), and by a slightly shorter skull. No such shrew was known from the central Congo basin before. The C. hildegardeae group includes a number of taxa, mainly from eastern Africa, which are poorly known. C. hildegardeae is larger (specimens from eastern and southern DRC in SMNS, ZFMK, and UA), has a higher pilosity (56.6 %), longer hindfeet (10.3–14 mm), and a slightly longer skull (CIL 18.1–20.3 mm). There are seven further taxa from Uganda and Kenya (C. h. maanjae Heller, 1910, C. h. altae Heller, 1912, C. h. lutreola Heller, 1912, C. h. procera Heller, 1912, C. h. ibeana Dollman, 1915, Crocidura macowi Dollman, 1915, C. h. rubecula Dollman, 1915), which are all larger than the new species (Dollman 1915; Heller 1910, 1912; Kerbis Peterhans et al. 2013).

3.3 Crocidura lwiroensis Kerbis Peterhans et Hutterer, in Kerbis Peterhans et al. 2013

Specimens: ZFMK 2023.0476 – 2023.0478 (BINCO_DRC_22_0705c, 0705d, 0689a) (Salonga NP, lowland camp, 371 m (01°39′57.5″S, 20°31′58.1″E), collected by Merlijn Jocque, 12 December 2022. BE_RMCA_Vert.2024.004.M.0001-3 (BINCO_DRC_22_0824a, 0824b, 0853); Salonga NP, highland camp, 505 m (02°17′15.6″S, 21°01′18.8″E), collected by M. Jocque and Brogan Pett, 4–6 December 2022.

Description: This is a very small shrew with a short tail, with longer bristles over 19.2 % (11.1–25.7 %; n = 7) of its length (Figure 2). Hindfeet are very short. Body hairs short (3 mm) at dorsum and 2 mm at ventrum. Colour of hairs at both dorsum and ventrum deep dark brown. Fore-, hindfeet, tail and ears of almost the same dark colour as the body. Ears shorter and dark. Skull short and stout (Figure 5), interorbital region strongly divergent, 14.9 % of the CIL; front part 40.5 %, braincase in dorsal view 44.6 % of CIL.

Figure 5:

Dorsal, ventral, and lateral views of the skull of (A, B, C) C. lwiroensis (ZFMK 2023.0476).

Measurements (holotype FMNH 195181 in parentheses): HB 52.3 mm; 43–56 mm; n = 6 (65 mm), T 38.8 mm; 31–45 mm; n = 6 (45 mm), TP 19 %; 11.1–25.7 %; n = 6 (20 %), HF 10.1 mm; 9.5–11 mm; n = 6 (10.2 mm), E 5.7 mm; 5–7 mm; n = 6 (8 mm). CIL 17.98 mm; 17.43–18.29 mm; n = 4 (18.26 mm), PL 7.36 mm; 7.02–7.7 mm; n = 6, GW 8.03 mm; 7.72–8.24 mm; n = 4 (8.42 mm), BW 5.55 mm; 5.28–5.95 mm; n = 6 (6.04 mm), IO 3.65 mm; 3.28–4.16 mm; n = 6 (3.92 mm), PGL 5.77 mm; 5.53–6.2 mm; n = 5 (6.09 mm), UTR 7.92 mm; 7.58–8.13 mm; n = 6 (7.91 mm), LTR 7.26 mm; 6.90–7.59 mm; n = 6 (7.31 mm), COR 4.11 mm; 3.86–4.36 mm; n = 6 (4.32 mm).

Comments: C. lwiroensis has a slightly higher tail pilosity (19.2 %) than C. binco sp. nov. (15.8 %), but much lower than in C. hildegardeae (56.6 %). The skull is shorter than in the other two co-existing species and has an almost straight dorsal profile (Figure 5). These are the first specimens collected after the description of the species, based on a single specimen from a montane locality (1,280 m asl) near Lake Tanganyika (Kerbis Peterhans et al. 2013). External and cranial measurements of the holotype from SE Congo and the new specimens from the Salonga NP agree rather well, and there is little doubt that they represent the same taxon. The new records extend the altitudinal range of the species from 371 to 1,280 m asl.