taxonID	type	description	language	source
11517770FFED141BFF715AC6FBAAAF23.taxon	materials_examined	Type material studied. The holotype (NHMUK ZD 1920.7.26.28; Figs 5 – 10) is an adult male collected at 6000 feet (1830 m) on Gunung Manusela, Seram Island, South Maluku (Fig. 1). The label indicates “ trapped in heavy jungle. ” Collected by the Pratt brothers in January 1920 and described by Oldfield Thomas in the same year (Thomas, 1920). Two other specimens were collected by the Pratt brothers at the same altitude (NHMUK ZD 1920.7.26.29 and NHMUK ZD 1920.7.26.30). All of these specimens are held by the Natural History Museum, London (NHMUK). Referred specimens. Another adult male was trapped in 1987 by a Western Australian Museum field crew headed by D. J. Kitchener (WAM M 33490; Helgen, 2003).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFED141BFF715AC6FBAAAF23.taxon	discussion	Taxonomic history. Thomas (1920) originally described R. ceramicus as a species of Stenomys based on his concept of the genus at that time, although he noted that the new species only superficially resembled Stenomys from New Guinea (“ this species … is really very different ”) based on features of the auditory bullae and palate. In the past, small mountain rats from New Guinea were most commonly placed in this genus (type species Stenomys verecundus), which is currently synonymized with Rattus. Thomas (1922) later established a monotypic genus, Nesoromys, for ceramicus, an arrangement maintained by Aplin et al. (2003) and Musser & Carleton (2005), but not supported by our results (although there is a broader potential need to redefine the generic name of Rattus from the Australo-Papuan region, the Maluku Islands, and also the Rattus xanthurus species group from Sulawesi; see ‘ Discussion’ below). On the basis of our molecular results and our morphological comparisons, we definitively place the species here within a monophyletic radiation of Australo-Papuan and Moluccan Rattus (see Discussion) and recover it as the sister species of Rattus feliceus, another Seramese endemic (Fig. 2).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFED141BFF715AC6FBAAAF23.taxon	distribution	Distribution. Rattus ceramicus has only been recorded from Gunung Manusela, but may also occur in other higher elevation areas on Seram. Its recorded altitude range is 1500 – 1830 m (Helgen, 2003).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFED141BFF715AC6FBAAAF23.taxon	diagnosis	Emended diagnosis. Rattus ceramicus is a small rat with soft and dull rufous fur covering both the upper and lower parts of the head and body (Fig. 5). This species is characterized by the following features: (1) a dark brown monochromatic tail almost equal to the length of the head and body (TL / HB = 104 – 107 %; Table 2); (2) long hind feet relative to the length of the head and body; (3) weak interorbital and postorbital ridges and only weakly developed temporal ridges (Fig. 6); (4) the bony palate protruding well beyond the upper molar 3 to form an extensive bony shelf, which is the most distinctive feature of this Rattus species (Fig. 7); (5) a narrow zygomatic plate and shallow zygomatic notch (Fig. 8); (6) a long and narrow rostrum; (7) viewed laterally, the dorsal outline of the skull forms a convex arc between the nasal tips and the occipital bone; (8) the zygomatic arch is broadly widened parallel to the upper dentary; (9) in ventral view, the squamosal root of the zygomatic arch is anterior to the level of the tympanic bulla; (10) in ventral view, the maxillary root of the zygomatic arch is placed at the level of the first upper molar (M 1); (11) the posterior margins of the very short incisive foramina terminate well anterior to M 1; (12) the condyloid process of the dentary is elongated, upwardly directed and curved; (13) the angular process does not project beyond the posterior part of the condyloid process and is not well developed; (14) the incisors are opisthodont with a narrow tip blade that is smaller than its longest basal width (an abnormal notch is present on the upper incisor in the specimen vouchered as WAM M 33490); (15) a posterior cingulum is present on M 1 but is weakly developed (Fig. 9); (16) cusp t 3 is present on M 2 but absent on the third molar; (17) t 1 bis is present on the first maxillary molar; (18) cusp t 1 of M 1 is either at the same level as or slightly posterior to cusp t 3, cusps t 1 + t 2 + t 3 form a U-shaped lamina; (19) anterolabial and posterolabial cusplets are present on lower molar 1 (m 1; Fig. 10); (20) an anterolabial cuspid and posterolabial cusplet are present on m 2 of the holotype, but a comparable cusplet is not visible on the other NHMUK and WAM specimens; (21) m 3 has an anterolabial cuspid but lacks a posterolabial cusplet.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFED141BFF715AC6FBAAAF23.taxon	biology_ecology	Ecology. Nothing is known about the ecology of this species except that it was collected in primary montane forest at 6000 ft (about 1830 m). It co-occurs with species of Melomys (Melomys aerosus, Melomys fraterculus, Melomys fulgens, and Melomys paveli) as well as Rattus feliceus and the two introduced species of Rattus found in Seram mountains — R. nitidus and R. exulans (Helgen, 2003). Judging by its relatively short tail and elongated hind feet, R. ceramicus is probably terrestrial in lifestyle.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFED141BFE865A3DFE2EAB36.taxon	type_taxon	Type species Mus decumanus Pallas, 1779 = Rattus norvegicus (Berkenhout, 1769)	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFEC1404FEB25F2FFAC8A9FC.taxon	materials_examined	Type material studied. The type specimen (NHMUK ZD 1920.7.26.7) is an adult female collected at 6000 feet (1830 m) on Gunung Manusela, Seram Island, South Maluku (Figs 5 – 10). This specimen was caught by the Pratt brothers in February 1920 and described by Oldfield Thomas in the same year (Thomas, 1920). Four other specimens were collected by the Pratt brothers between 1200 m and 1830 m (NHMUK ZD 1920.7.26.4 – 6 and NHMUK ZD 1920.7.26.8). The zoological expedition to Seram that produced the original specimens was undertaken by three of the four sons of the Victorian naturalist A. E. Pratt from late 1919 to early 1920. Oldfield Thomas (1920) remembered Felix Pratt, for whom he named “ this fine species. ” The label states that it was collected “ in heavy jungle in precipitous limestone country. ” All of these specimens are held by the Natural History Museum, London (NHMUK). Referred specimens. Three adult females and one subadult male were captured by an Australian Museum field team in 1993 between 300 and 400 m (Flannery, 1995; Helgen, 2003). An additional specimen from Gunung Manusela was collected more recently by Museum Zoologicum Bogoriense ornithologists (MZB 22684).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFEC1404FEB25F2FFAC8A9FC.taxon	distribution	Distribution. Rattus feliceus is found from lowland to highland contexts (0 – 2000 m) at several localities on Seram, and may be widespread on the island.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFEC1404FEB25F2FFAC8A9FC.taxon	diagnosis	Emended diagnosis. Rattus feliceus is a large-bodied rat with spiny, reddish-brown fur over the upperparts and softer white fur covering the belly; the dorsal fur contrasts sharply with the white ventral fur (Fig. 5). The mammae formula (given in pairs plus total number) is: 1 pectoral, 1 post-axillary, 0 abdominal and 2 inguinal (1 + 1 + 0 + 2 = 8). This Rattus species is characterized by the following features: (1) a single-coloured pale brown tail shorter than the head-body length (TL / HB = 68 – 91 %; see also Table 2 and Fig. 5), (2) slender and elongated hind feet, but of medium length compared to the head-body length, (3) a moderately long and broad rostrum, (4) prominent temporal, interorbital and post-orbital ridges (Fig. 6), (5) the palatal bridge protruding well beyond M 3 to form a moderately large bony shelf (Fig. 7), (6) a wide and deep zygomatic notch and a wide zygomatic plate, (7) viewed laterally, the upper edge of the skull is almost flat between the nasals and the occiput, (8) the eustachian tube is shorter and narrower than in R. ceramicus, (9) the angular process of the dentary is broad, (10) the large incisors are opisthodont, (11) the incisor blade is broad, with a size equal to or greater than its longest basal width, (12) the posterior cingulum forms a small bulge on M 1 (Fig. 9), (13) cusp t 3 is present on both M 2 and M 3, (14) t 1 bis is absent on M 1, (15) cusp t 1 on M 1 is posterior to cusps t 2 and t 3 and forms a pinched lingual bulge on the M 1 lamina, (16) cusp t 8 on M 1 and M 2 is well developed compared to other cusps, (17) there is no anterolabial cusp on m 1 (Fig. 10), (18) the posterolabial cusplet is always present on m 1, (19) anterolabial cuspid and posterolabial cusplet are present on m 2, (20) the presence of posterolabial cusplet is variable on m 3 (present in two specimens). Comparisons between Rattus ceramicus and Rattus feliceus: Despite a relatively small molecular divergence (4 % Cytb nucleotide divergence) between R. ceramicus and R. feliceus (Fig. 2), these two taxa are strikingly different in their external and cranial morphology. At the same time, they share features that clearly distinguish them together from other Moluccan Rattus (Figs 2, 5 – 10). The very distinct external appearance of these two species of Seram rats masks their close relationship. Rattus feliceus is a large-bodied rat with a clearly defined dorsal and ventral coat, and is at least twice the mass of the small, dark, single-coloured R. ceramicus (Figs 3 and 5; Table 2). In terms of coat texture, R. feliceus has a harsh and very spiny coat compared to the soft, short coat of R. ceramicus. Tail proportions are also different, as R. feliceus has a low TL / HB ratio (68 – 91 %) compared to the almost equal TL / HB ratio of R. ceramicus. Regarding the skull (Figs 6 – 8), the interorbital, postorbital and temporal ridges are well developed in R. feliceus compared to R. ceramicus. The dorsal contour of the skull in lateral view is almost flat from the nasals to the highest point of the skull (occiput) in R. feliceus, whereas it is slightly convex in R. ceramicus. The rostrum of R. ceramicus is thinner and longer relative to the size of the skull than the bulky rostrum of R. feliceus. The zygomatic plate and arch are narrower and more slender in R. ceramicus than in R. feliceus. In R. ceramicus, the maxillary root of the zygomatic plate is at the level of the first upper molar; this, together with the slender rostrum, is in many ways reminiscent of the structure found in some shrew rats, such as Archboldomys (Musser, 1982; Balete et al., 2012), or to a lesser extent Melasmothrix naso and Tateomys macrocercus (Musser, 1982). Most of the maxillary root in R. feliceus is located anterior to the first upper molar. The jugular process is also proportionally longer in R. feliceus. The posterior palatal foramina reach the middle of M 3 in R. feliceus but extend posteriorly to M 3 in R. ceramicus. The incisive foramina of R. ceramicus are short and do not reach M 1, compared to the long and wide incisive foramina of R. feliceus, in which the posterior margins of the incisive foramina reach the anterior edge of M 1. The palatal bridge extends well beyond M 3 in R. ceramicus compared to R. feliceus; although other species have a long palatal bridge, that of R. ceramicus is relatively longer and extends further posteriorly than in most members of the Rattus Division. The tympanic bullae of R. ceramicus are slightly more distended than those of R. feliceus relative to the length of the skull. The zygomatic notch is closer to the zygomatic plate in R. feliceus than in R. ceramicus. The incisors are opisthodont and the enamel is orange, but the incisor blades of R. ceramicus are narrower than those of R. feliceus. On M 1 the cusp t 1 bis is present in R. ceramicus and absent in R. feliceus (Fig. 9). Cusp t 3, present on M 3 of R. feliceus, is absent on M 3 in R. ceramicus. Cusp t 1 on M 1 differs in its position in relation to t 2 and t 3; the latter two cusps are more anterior to t 1 in R. feliceus compared to R. ceramicus. The cusps on the upper molars are more divided in R. feliceus compared to R. ceramicus, giving a more chevronate structure, and each upper molar appears more elongate. The shape of the lower molars (Fig. 10) is similar in both taxa, with some differences in the cusplets – the anterolabial cusplet of m 1 is absent in R. feliceus and present in R. ceramicus, and the posterior cingulum of m 1 and m 2 is proportionally smaller in R. feliceus than in R. ceramicus. Ecology. Little is known about the ecology of Rattus feliceus, except that the few existing specimens were collected in forest ranging from coastal forest at sea level to primary montane moss forest up to 1830 m. This species co-occurs with species of Melomys (M. aerosus, M. fraterculus, M. fulgens, and M. paveli) as well as R. ceramicus and at least two introduced species of Rattus, R. exulans and R. nitidus (Helgen, 2003). Rattus feliceus is probably terrestrial in lifestyle (Flannery, 1995), especially judging by its short tail and long hind feet relative to head and body length (Table 2).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF21407FC4A5B14FE37AB10.taxon	materials_examined	Type material studied. The holotype, an adult female, was collected by J. J. Menden between September and October 1938 on the plains of Taliabu Island (MZB 4087), probably at sea level. The tag indicates the following location: Soela Islands (Sula Archipelago), Taliaboe (Taliabu Island), “ plains ”. Sody (1941) did not comment on his choice of “ elaphinus ” (“ deer-like ”) as the species name, but presumably applied it to describe the fulvous dorsal pelage colour exhibited by this species. Referred specimens. At least 33 specimens of this species were collected by Menden from Taliabu Island. Tim Flannery subsequently collected four specimens on Mangole Island but did not find the species on nearby Sanana Island (Flannery, 1995).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF21407FC4A5B14FE37AB10.taxon	diagnosis	Diagnosis. Rattus elaphinus is a medium-sized rat with a soft coat that is buffy grey on the underparts and reddish brown on the upper parts (Fig. 11). This species is characterized by the following features: (1) a monochromatic dark brown tail subequal to the head-body length (TL / HB = 93 – 102 %; Table 2); (2) hind feet of medium length in relation to the head-body length; (3) interorbital and postorbital ridges well developed, as well as the temporal ridges (Fig. 6); (4) the zygomatic plate is broad, the rostrum is moderately long and wide and appears chunky; (5) the palatal bridge projects beyond M 3 as a moderately extended bony shelf (Fig. 7); (6) viewed laterally, the skull is almost flat (slightly convex) between the nasal tip and the occiput (Fig. 8); (7) the posterior palatal foramina are located between M 2 and M 3 or at the anterior level of M 3; (8) the eustachian tube is short; (9) the post-glenoid cavity is not fused with the middle lacrimal foramen in most specimens; (10) the posterior margins of the wide and long incisive foramina reach M 1; (11) the incisor enamel is orange and the upper incisors are either opisthodont or orthodont relative to the rostrum; (12) the incisor blade is wide and equal to or greater than its longest basal width; (13) the posterior cingulum is either absent on M 1 or rarely forms a slight bulge; (14) cusp t 3 is reduced or absent on M 2 but absent on M 3 in all specimens observed; (15) t 1 bis is absent on M 1; (16) cusp t 1 of M 1 is well separated from cusps t 2 and t 3; (17) the anterocentral cusplet is absent on m 1 (Fig. 9); (18) anterolabial and posterolabial cusplets are present on m 1 in most specimens (Fig. 10), apart from one individual (MZB 4078) which lacks an anterolabial cusplet; (19) anterolabial cuspid and posterolabial cusplet are present on m 2; (20) m 3 has an anterolabial cuspid which may disappear with wear in older specimens; (21) the formula for the mammae is 1 pectoral + 1 post-axillary + 0 abdominal + 2 inguinal mammae (1 + 1 + 0 + 2 = 8).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF21407FC4A5B14FE37AB10.taxon	discussion	Comment. No molecular data are yet available for this species. Rattus elaphinus is morphologically very close to the R. leucopus group (an Australo-Papuan lineage; Musser & Carleton, 2005) and in some ways to R. hoffmanni (Musser & Holden, 1991) and is the only Moluccan Rattus to be included in a previous morphological systematic revision of Rattus, by Musser & Holden (1991), which focused on the systematics of R hoffmanni. As R. hoffmanni is closely related to R. argentiventer (Rowe et al., 2019) as well as to other Asian Rattus species belonging to the R. rattus and R. norvegicus clades, R. elaphinus may also be closely related to this clade. Sody’s (1941) description of the species is amplified by a detailed description and comparison with R. hoffmanni by Musser & Holden (1991: 386 – 388).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF21407FC4A5B14FE37AB10.taxon	biology_ecology	Ecology. Little is known about the ecology of R. elaphinus. All individuals have been caught near sea level (Flannery, 1995). This species is probably terrestrial in lifestyle, judging from the relative lengths of the tail and hind feet. The Taliabu species R. taliabuensis sp. nov. and R. feileri sp. nov. co-occur with R. elaphinus.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF11400FEB45AAEFBE1AB63.taxon	description	urn: lsid: zoobank. org: act: BEB 15 FE 6 - 3 CA 4 - 439 E- 9688 - BE 8 A 07 C 59 E 75 Figs 6 e, 7 e, 8 e, 9 e, 10 e, 11 a, d, 12 b, 13 g, 14 g, 18 a	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF11400FEB45AAEFBE1AB63.taxon	materials_examined	Holotype. The holotype (in Staatliche Naturhistorische Sammlungen Dresden, Museum für Tierkunde, SNSD 11429) is a young adult (scrotal) male collected by J. J. Menden on 30 September 1938 (original number 68) on “ Insel Taliaboe Molukken ” (Taliabu Island, Maluku). Method of collection and exact locality are not known. The skin is very well preserved. The skull is intact except for the zygomatic arches which are detached from their squamosal roots. Known only from the holotype. Type locality. Taliabu Island (Fig. 1), Maluku, Indonesia.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF11400FEB45AAEFBE1AB63.taxon	etymology	Etymology. We name this species in honour of German zoologist Alfred Feiler, who worked at the Staatlichees Naturhistorische Sammlunggen in Dresden until his retirement. Feiler kindly arranged the loan of Taliabu Island specimens to G. G. Musser, assisted K. M. Helgen on several visits to the museum in Dresden, and helped with our research in many other ways. We commemorate his significant contributions to knowledge of the mammal fauna of the Indo-Pacific region, and to Wallacea and Maluku in particular.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF11400FEB45AAEFBE1AB63.taxon	distribution	Distribution. Known only from the type locality, Taliabu Island (Fig. 1), Maluku, Indonesia.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF11400FEB45AAEFBE1AB63.taxon	diagnosis	Diagnosis. Rattus feileri is of medium size, with a spiny coat overall, which is reddish grey on the upperparts and pale ochraceous, buff or whitish on the undersides, with a rusty wash on parts of the chin, forelegs and chest (Fig. 11). The tail is long in relation to the length of the head and body (TL / HB = 134 %; Table 2), with a terminal tuft or “ pencil ” (Fig. 12). This species is also characterized by the following features: (1) a dark brown tail much longer than the length of the head and body; (2) moderately long and wide hind feet relative to the length of the head and body (Table 2); (3) upper incisors orthodont, with orange enamel faces; (4) wide incisor blade, width at tips greater than longest basal width (Fig. 7); (5) short and wide rostrum with shallow zygomatic notch (Fig. 6); (6) viewed laterally, the top of the skull is convex between the nasal tips and the occiput (Fig. 8); (7) posterior palatal foramina level with the posterior portion of M 2; (8) posterior margin of palatal bridge does not extend beyond the posterior margins of M 3, which is unusual in the species of Rattus examined here; (9) wide and moderately long eustachian tube; (10) the post-glenoid vacuity is not fused with the middle lacrimal foramen; (11) the incisive foramina are long and narrow with their posterior margins aligned with the anterior surface of M 1; (12) M 2 is bulky and slightly wider than M 1 and M 3 (Fig. 9); (13) posterocone is absent on M 1; (14) cusp t 3 is present on M 2 and M 3, and is wider on M 3; (15) t 1 bis is absent on M 1; (16) cusp t 1 on M 1 is slightly posterior to cusps t 2 and t 3 and forms a well separated cusp; (17) anterolabial and anterolingual cuspids as well as an anterocentral cusplet are present and fused to form the anteroconid on m 1, likely due to dental wear (Fig. 10); (18) an anterolabial cuspid and posterolabial cusplet are present on m 2; (19) m 3 shows a ridge-like anterolabial cuspid but lacks the posterolabial cusplet. The mammae formula is unknown, the only available specimen being male.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF11400FEB45AAEFBE1AB63.taxon	description	Description and comparison with Taliabu Rattus and R. morotaiensis, R. halmaheraensis and R. obiensis. Rattus feileri is of medium body size with a distinctive long tufted tail (Table 2 and Figs 11 – 12) and moderately long hind feet, and is similar in proportions to Rattus halmaheraensis sp. nov. and Rattus obiensis sp. nov. Apart from its superficial resemblance to these two species in external proportions, Rattus feileri has no morphological counterpart elsewhere and cannot be confused with any known species of Indo-Pacific Rattus. Its unusually long tail has a rare feature found only in this Rattus lineage and to a lesser extent in the Rattus morotaiensis group: a rufous, tufted tail (Fig. 12). Other murine species, such as Chiropodomys karlkoopmani, have similarly developed tufted tails (Musser, 1979), but a pencil tail has never been reported in any other Rattus species. Rattus feileri is also characterized by distinctive brown, square or hexagonal tail scales. For most of its length, the tail is covered with fine reddish-brown hairs the length of a single scale; near the tip, the hairs are less abundant but longer, forming a tuft that extends 10 mm beyond the tip of the tail. There are approximately 9 – 11 scale rows per centimetre measured near the base of the tail, each scale bearing 3 hairs. The dorsal coat bears a mixture of (1) spines with white bases and rufous or dark rufous tips, (2) soft guard hairs, (3) charcoal grey undercoat that is almost woolly, and (4) long and stiff guard hairs that are dense with white or buff bases and rufous tips (Fig. 11). The dorsal fur is generally spiny and greyish-reddish chestnut with a few ivory thin spines. The spines of R. feileri are shorter than the stiff guard hairs which are thin and tubular, shorter on the shoulders (1.0 – 1.7 mm) and longer on the rump (3.0 – 3.5 mm). The rump hairs are longer than other areas of the dorsal coat such as the head and shoulders. Like R. taliabuensis and some spiny rats (e. g., Halmaheramys), R. feileri has longer guard hairs and longer spines on the rump. The guard hairs and spines do not completely cover the undercoat, giving a layered appearance. There appears to be a lateral line separating the dorsal and ventral coats. The ventral coat is softer and less dense than the dorsal coat and is predominantly buff or pale ochre with thinner spines and a greyish white woolly undercoat, except on the chin, throat and chest. Here the coat darkens to a chestnut colour, probably the result of staining. Some of the ventral spines have brown tips and are more sparsely distributed from the pectoral region caudad to the pelvic region. Compared to the Rattus morotaiensis group, R. feileri has a less spiny coat, a more rufous dorsal coat and a denser undercoat. The skin of the forelegs is brownish dorsally and ventrally, covered with tiny pale hexagonal scales. The fur on the forefeet is greyish-white with buff or rusty patches. Coloration of the dorsal and ventral sides of the foreleg are well defined. Considering the forefoot, the first digit is reduced, leaving only a small first interdigital pad projecting medially. The other four digits are long and appear to be of equal length. All four have digital pads and the scales on the digits are annular. The forefeet have three almost equal interdigital palmar pads and two large thenar and hypothenar pads, similar to the R. morotaiensis group. The fingers are elongated compared to R. taliabuensis, with large terminal digital pads and long curved claws with silvery hairs on their anterior edges. The claws also bear some silvery hairs that are nearly as long as the claw lengths. On the hindfeet the first digit is reduced and appears approximately half the length of the other four, which are subequal in length. All the digits have digital pads, and as on the hands the scales on the digits are annular. The first and fourth interdigital pads are larger than the second and third, the metatarsal pads are elongated. The head is characterized by moderately long bicoloured ears clothed with creamy or brownish fur near the notch (11 mm) and dark brown fur at the apex (4 mm). A distinctive trait that aids in identification of R. feileri is the presence of dark eye-rings encircled by dark brown hairs that are well demarcated from the paler facial fur. The mystacial whiskers are long (55 – 70 mm maximum length) and rufousbrown throughout their length or tipped in silver. The three superciliary and genal whiskers are also moderately long and caudal to the eyes. There is a tuft of blond ulnar carpal vibrissae above each wrist. The coat colour and skull proportions of R. feileri appear similar to the R. morotaiensis group, but the skull bears several discrete features not present in other Moluccan rats. Dorsally, the rostrum is short and broad compared to R. morotaiensis and R. halmaheraensis sp. nov. (Fig. 6 and Fig. 18). The rostrum appears to be enlarged posteriorly with a proportionally wider nasal area. The zygomatic plate does not extend significantly anteriorly as in the R. morotaiensis group. The postorbital region is only slightly ridged, similar to R. halmaheraensis sp. nov. Another clear distinction from the R. morotaiensis group is a zygomatic arch that does not curve as strongly posteriorly as in R. elaphinus. Compared to R. elaphinus, the rostrum of R. feileri is very short and the braincase is wider. In lateral view, the braincase of R. feileri is curved, with the height of the braincase dropping significantly from the top of the parietal bones to the tip of the nasal bones. The zygomatic plate of the holotype does not extend significantly anteriorly, and the squamosal root of the zygomatic arch inserts high above the auditory bulla. The zygomatic arch does not extend ventrally and does not reach the upper molar row in lateral view. The tympanic bulla is not inflated. The skull of R. feileri appears more bulky in ventral view than the skull in species of the R. morotaiensis group (Fig. 7, Fig. 18). In ventral view, the incisor blades are wide compared to their basal length, as in R. elaphinus and R. taliabuensis (Fig. 7). The incisive foramina are long and extend towards M 1. One of the most distinctive features distinguishing R. feileri from the R. morotaiensis group is the wide and bulky upper molars (M 2 is wide compared to M 1 and M 3) and a palatal bridge that does not extend beyond M 3. The molars are generally much wider and more massive than those of the R. morotaiensis group. The tympanic bullae are also proportionally larger in R. feileri than in R. morotaiensis species. The jaw of R. feileri is similar to that of the R. morotaiensis group, with a narrow incisor alveolus and a short angular process that does not extend beyond the articular process. The jaw of R. feileri is more gracile compared to larger rats such as R. taliabuensis and R. feliceus.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF11400FEB45AAEFBE1AB63.taxon	discussion	As discussed above, the dentition of R. feileri is easily distinguished from all Taliabu Rattus and species within the R. morotaiensis group by its wider and more robust molars. The teeth of the R. xanthurus species group from Sulawesi are very similar in shape to R. feileri and are also wide and robust (Figs 13 – 14); however, cusp t 3 on the M 1 of R. xanthurus group species is larger and has a well-defined boundary in the first lamina as compared to all Moluccan Rattus (Fig. 13). In R. feileri, M 2 is wider than M 1 and M 3 and square in shape (Fig. 9), and both M 2 and M 3 have a cusp t 3 on the holotype. Cusp t 3 on the third upper molar is well developed and wider than on M 2, a feature also found in the R. xanthurus species group. On M 1, the first lamina has a well-separated cusp t 1 posterior to cusps t 2 and t 3 and the posterocone is absent. The lower molars of R. feileri are also relatively wide (Fig. 10) and likewise bear resemblance to species in the R. xanthurus species group. Anterolabial and anterolingual cuspids, as well as an anterocentral cusplet, are present and are fused together to form the anteroconid on m 1, likely due to dental wear. An anterolabial cuspid and posterolabial cusplet are present on m 1 and m 2; m 3 has only a ridge-like anterolabial cusplet.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF11400FEB45AAEFBE1AB63.taxon	biology_ecology	Ecology. Little is known about the ecology of this species. Judging from its morphological features it is probably arboreal or at least scansorial. The presence of a long, tufted tail and a short, chunky rostrum are usually associated with arboreal habits in murines. Given ongoing habitat disturbance on Taliabu due to logging, agriculture, and forest fires (Rheindt, 2010), this species may be threatened or even possibly extinct, though much more survey work is required to more fully understand the extant mammal fauna of Taliabu. Rattus feileri probably co-occurs with Rattus taliabuensis and Rattus elaphinus.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF6140CFC4D5A54FD9BA9F3.taxon	description	urn: lsid: zoobank. org: act: 05 A 95 DE 3 - 1 F 93 - 4 C 3 C-A 581 - 81 AB 5 C 971 FA 1 Figs 6 d, 7 d, 8 d, 9 d, 10 d, 11 c, f	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF6140CFC4D5A54FD9BA9F3.taxon	materials_examined	Holotype: The holotype is an adult (scrotal) male collected by the commercial collector J. J. Menden on 27 September 1938 on “ Insel Taliaboe Molukken ” (Taliabu Island, Maluku) and labelled SNSD 119968 (in Staatliche Naturhistorische Sammlungen Dresden, Museum für Tierkunde). Method of collection and exact locality are not known. The skin is in good condition, with the tail slightly split across its length due to skin preparation. The skull is intact apart from a broken basioccipital and tympanic bulla. The holotype is the only known specimen. Type locality. Sula Islands, Taliabu Island. The label indicates a 300 m altitude for the type locality.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF6140CFC4D5A54FD9BA9F3.taxon	etymology	Etymology. Rattus taliabuensis is named after its geographical provenance, from Taliabu in the Sula Archipelago, Maluku, off eastern Sulawesi.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF6140CFC4D5A54FD9BA9F3.taxon	distribution	Distribution. Known only from the type locality, Taliabu (Fig. 1), Maluku, Indonesia.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF6140CFC4D5A54FD9BA9F3.taxon	diagnosis	Diagnosis. Rattus taliabuensis is a large-bodied rat with a spiny coat that is dark reddish-brown on the upperparts (brown with reddish-brown guard hairs on the back) and lighter reddish-brown on the underparts (Fig. 11). This rat has a short tail compared to its head and body length (TL / HB = 70 %; see also Table 2), with large tail scales. This species is distinguished from all other species of Rattus by the following set of characters: (1) a dark tail, shorter than its head-body length (Table 2); (2) short hind feet relative to head-body size; (3) the incisor enamel is orange and the upper incisors are opisthodont in conformation; (4) the incisor blade is moderately narrow and its size is less than or equal to its longest basal width; (5) the zygomatic plate is wide and the rostrum is long and narrow; (6) laterally, the skull is almost flat between the nasal tips and the occiput; (7) the posterior palatine foramina are at the level of the anterior part of M 3; (8) the palatal bridge extends beyond M 3 to form a broad bony shelf, as in most of the other Rattus species considered here; (9) the eustachian tube is large (long and wide, Fig. 7); (10) the post-glenoid cavity is not fused with the middle lacerate foramen; (11) the posterior margins of the long and wide incisive foramina reach the levels of the first upper molars; (12) the posterior cingulum is absent on M 1 and M 2 (Fig. 9); (13) cusp t 3 is present on M 2 but not on M 3; (14) t 1 bis is absent on M 1; (15) cusp t 1 of the first upper molar is at the same level as cusps t 2 and t 3; (16) there is no anterocentral cusplet on m 1 (Fig. 10); (17) anterolabial and posterolabial cusplets are present m 1; (18) anterolabial cuspid and posterolabial cusplet are present on m 2; (19) only an antero-labial cusplet is present on m 3. The mammae formula is unknown, the only known specimen being an adult male.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF6140CFC4D5A54FD9BA9F3.taxon	description	Description and comparison with Rattus feliceus and Rattus elaphinus: Rattus taliabuensis is a large, dark rufous rat with a short tail measuring 70 % of the length of the head and body (Table 2 and Fig. 11). The fur covering the upper parts is rufous, with longer guard hairs on the rump. The coat is very spiny, with some long spiny guard hairs prominent on the rump (20 – 30 mm) and shorter ones on the head, neck, and shoulders (6 – 20 mm). There are long reddish guard hairs with dark tips, which are more sparsely distributed in the antero-dorsal region. The front of the body is paler and more rufous than the back, which is darker. The belly is lighter with a few medium sized, hard spines that vary from cream rufous, orange rufous to dark rufous. There is a darker area at the base of the scrotum and between the shoulders. Despite some similar external proportions between R. feliceus and R. taliabuensis, their colour pattern is very different, with R. feliceus having both a distinctive white belly and a darker colouration on the upperparts. The overall orange-red belly colouration of R. taliabuensis is quite distinct from all Maluku rats. Like several other species of Indo-Pacific Rattus, R. taliabuensis is covered with very spiny hairs, although the spines are not as thick as those of R. feliceus and R. morotaiensis. These spines have a thin base and are white in colour with dark brown or orange tips. The guard hairs between these spines have a grey base with an orange or dark brown tip. Similar to the morphology of Halmaheramys bokimekot and H. wallacei (Fabre et al., 2018: 192, fig. 2 C), this species has some long guard hairs that extend onto the rump fur. In terms of external proportions, R. taliabuensis is characterized by a shorter tail (70 % of head body length) and a shorter hind foot length than any other Moluccan species (Table 2 and Fig. 11). Its short tail is very characteristic due to the presence of large squarish scales (6 – 7 scale rows per centimetre measured near the base of the tail), all of which contain very short hairs half the length of a tail scale. These square-shaped tail scales are very rare in murids from the region and are only found in Halmaheramys bokimekot and H. wallacei, albeit with spiny hairs instead. The forefeet of R. taliabuensis exhibit the normal Rattus morphology, with three interdigital pads and thenar and hypothenar pads. The morphology of the forefeet is also distinctive with two large thenar and hypothenar pads and a central interdigital pad larger than both lateral and medial pads. The dorsal part of the hand is almost bare, with very small scales covered with tiny rufous hairs. The toes are strong and short, with short and narrow claws. The claws on the forefeet are small and almost devoid of fine hair. The chunky, short toes on the forefeet contrast with the thinner and longer toes of R. elaphinus from Taliabu. The hind feet of R. taliabuensis are broad with a moderately long thenar pad and a small hypothenar pad. The pale dorsal part of the hind foot contrasts well with its darker ventral side. There are more silvery hairs covering the dorsal part of the hind feet, as well as a small tuft of silvery hairs on the edge of the claws. This rat has very long reddish mystacial vibrissae (50 – 75 mm) extending beyond the posterior part of the ears. A few superciliary (30 – 45 mm) and 1 – 2 genal (25 – 30 mm) whiskers are also present, and these are moderately long compared to the mystacial whiskers. The small ears are dark brown and covered with tiny silvery hairs. Dorsally, the skull of R. taliabuensis is longer than that of R. elaphinus, with a proportionally longer rostrum (Fig. 6). The postorbital ridge is well developed. However, compared to R. elaphinus and R. feliceus, the postorbital ridge is reduced from the middle of the parietal. The zygomatic notch is similar to R. feliceus and reduced compared to R. elaphinus. On the lateral side, the zygomatic plate is broad, with a zygomatic arch that hangs well above the level of the molar row, as in other Taliabu and Moluccan Rattus. The top of the skull is flat as in R. feliceus and R. elaphinus. As in R. feliceus, the tympanic bulla of R. taliabuensis is not swollen (Fig. 8), and the middle lacerate foramen is well separated from the front of the tympanic bulla and connected to the post-glenoid foramen. The incisive foramen is shorter in R. taliabuensis than in R. feliceus. The palate of R. taliabuensis does not extend as far back from M 3 as in R. feliceus. The 2 most distinctive features of R. taliabuensis compared to R. feliceus and R. elaphinus are its wide and long eustachian tube and its reduced auditory bullae. The upper incisors are orange and opisthodont as in R. feliceus. The mandible of R. taliabuensis is also very similar to that of R. feliceus. Its angular process is broad and stocky, with a large anterior deep masseter ridge. The coronoid is broad and poorly developed (possibly broken due to poor cleaning), but otherwise similar to R. feliceus.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF6140CFC4D5A54FD9BA9F3.taxon	discussion	The molars of R. taliabuensis are narrower than those of R. feileri. Compared to R. elaphinus, they are slightly larger and morphologically similar (Fig. 7). There is a clear difference between the upper molars of R. taliabuensis and R. elaphinus. In fact, cusps t 1 and t 4 are less separated from their corresponding cusps t 2 + t 3 and t 5 + t 6, respectively (Fig. 9). These cusps t 1 and t 4 appear to be very small and well separated from their lamina in R. elaphinus, reminiscent of the molar morphology of R. hoffmanni (Musser & Holden, 1991), which is not the case in R. taliabuensis. Regarding the lower molars (Fig. 10), the morphology of R. taliabuensis includes a classical shape with a wide lamina, both anterolabial and posterolabial cusps are present and large on m 1 and m 2. In R. elaphinus they are present but smaller in proportion. The anterolabial cusplet of m 3 is wider than in all observed specimens of R. elaphinus. If the global morphology of the skull shape of R. taliabuensis is close to that of R. feliceus, the shape of their teeth is also similar (see Figs 9 – 10), with the anterolabial cusplet being significantly larger in R. taliabuensis.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFF6140CFC4D5A54FD9BA9F3.taxon	biology_ecology	Ecology. Little is known about the ecology of Rattus taliabuensis. Morphological features suggest that it is probably terrestrial in lifestyle. In rats, a short tail, large body size and broad feet are usually associated with terrestrial habits. Given ongoing habitat disturbance on Taliabu due to logging, agriculture, and forest fires (Rheindt, 2010), this species may be threatened or even possibly extinct, though much more survey work is required to more fully understand the extant mammal fauna of Taliabu. It probably co-occurs with Rattus feileri and Rattus elaphinus.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA140CFE915B6CFA74AA0E.taxon	materials_examined	Type material studied. The holotype (USNM 277312) is an adult male collected on Morotai (= Morty) Island on 25 October 1944 by J. F. Cassel and R. M. Roecker and described by Kellogg (1945). Six other specimens were also collected from the same locality (USNM 277309 – 277311; 277313 – 277315). Type locality. The type locality is Morotai Island, North Maluku, Indonesia. Referred specimens. One specimen was collected in 1991 by Indonesian mammalogist Boeadi (AM M. 26618) on Morotai Island. We also examined modern (AM M. 7083 – 7086) and subfossil specimens of Rattus morotaiensis discussed by Aplin et al. (2023).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA140CFE915B6CFA74AA0E.taxon	distribution	Distribution. Rattus morotaiensis is thus far known only on Morotai Island. All specimens have so far been collected at low elevations.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA140CFE915B6CFA74AA0E.taxon	diagnosis	Emended diagnosis. Rattus morotaiensis is a medium to large rat with a spiny coat that is dark reddish brown (Table 2 and Fig. 15). This species of Rattus is characterized by the following features: (1) a dark brown tail longer than its head and body length (TL / HB = 109 – 126 %, Fig. 3), sparsely haired and slightly tufted at the tip; (2) long hind feet relative to head and body length for this presumably scansorial or arboreal rat species (Table 2); (3) the postorbital ridge is well developed and marked, and the temporal ridge is well developed (Fig. 6); (4) the palatal bridge moderately extended behind M 3 (Fig. 7); (5) the zygomatic notch is moderately wide and the rostrum is short and narrow; (6) laterally, the skull is almost flat between the nasal and occipital (or slightly curved between the interparietal and frontal; Fig. 8); (7) in lateral view the zygomatic arch well upon the level of the upper molar row; (8) in ventral view, the zygomatic root of the zygomatic arch does not reach or just overlaps the level of M 1; (9) posteriorly, the incisive foramina are short and just reach or do not reach the front of M 1; (10) the usual mammae formula is 1 pectoral + 1 post-axillary + 0 abdominal + 3 inguinal (1 + 1 + 0 + 3 = 10), but one specimen has eight mammae (one of the paratypes from Morotai lacks a pair of pectorals, but see description in Kellogg, 1945); (11) the angular process does not extend behind the posterior part of the condylar process and is not very developed; (12) the incisor blade is narrow and its size is less than its longest basal width; (13) the posterocone is present on M 1 (Figs 9 and 13); (14) cusp t 3 is present on M 2 and usually on M 3; (15) cusp t 1 of M 1 is located just behind the level of cusps t 2 and t 3; (16) there are large and prominent peg-like anterolabial and anterolingual cuspids on m 1 (Figs 10 and 14); (17) anterolabial and anterolingual cuspids on m 1 are of almost equal size; (18) anterolabial and posterolabial cusplets are present on m 1 in most specimens, the anterolabial cusplet always being smaller than the anterolabial cuspid on m 1; (19) a wide cingular margin is present on m 2; (20) an anterolabial cuspid is always present on m 2 and m 3; (21) a posterolabial cusplet is always present on m 2 and absent on m 3; (22) strongly crenulated enamel is present on all molars.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA140CFE915B6CFA74AA0E.taxon	discussion	A detailed description of Rattus morotaiensis was also provided by Kellogg (1945), and a detailed comparison between R. morotaiensis and the two Rattus species from Halmahera and Obi can be found in the descriptions below.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA1409FC255BA3FAF6AB70.taxon	description	urn: lsid: zoobank. org: act: 89 C 27 A 8 B-B 0 CA- 4 CD 7 - 92 AF- 84 EDA 15944 EA Figs 6 g, 7 g, 8 g, 9 g, 10 g, 12 a, 13 a – c, 14 a – c, 15 b, e, 16 a, b, 19	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA1409FC255BA3FAF6AB70.taxon	materials_examined	Holotype. The holotype (in the Australian Museum, Sydney, AM M. 23652) is a young adult male collected on the island of Halmahera on 1 May 1991 by Tim Flannery near Goal, Sahu Timur, West Halmahera Regency (North Maluku Province, Indonesia). The skin, skull, and jaws are intact and in good condition. Paratypes. Three specimens from Halmahera collected in 1991 by an Australian Museum field crew headed by T. Flannery (AM M. 26614, female, body in fluid; AM M. 26615, male, skin, and skull; AM M. 26965, female, skin, and skull). Type locality. The type locality, in the northwest of the island of Halmahera Island (North Maluku Province, Indonesia), close to Goal locality (1.2115 ° N 127.56007 ° E). This trapping site was situated along the edge of primary forest.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA1409FC255BA3FAF6AB70.taxon	discussion	Referred specimens. Specimens previously attributed to Rattus morotaiensis from the island of Bacan (Flannery, 1995) are here referred to R. halmaheraensis, including AM M. 23653 (male, skin and skull), AM M. 23720 (female, body in fluid with skull extracted), AM M. 26616 (male, body in fluid), AM M. 26617 (female, body in fluid), and AM M. 27011 (male, skin and skull). A previously overlooked specimen in the Australian Museum, from Ternate (AM M. 23655, female, skin and skull, from Ayr Tege Tege, Ternate, collected 2 January 1991 by T. Flannery), is also referred to R. halmaheraensis. A team from MZB recently collected a large series of R. halmaheraensis on Halmahera (Fig. 1 and Appendix 1). Six specimens from the island of Moti (MZB 33573 – 7) are more tentatively referred here to R. sp. cf. halmaheraensis but may represent an additional undescribed species (see phylogenetic results, Table 1 and Fig. 2).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA1409FC255BA3FAF6AB70.taxon	etymology	Etymology. We name this species after the island of Halmahera, where the type locality is situated.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA1409FC255BA3FAF6AB70.taxon	distribution	Distribution. Rattus halmaheraensis is widespread on Halmahera (Fig. 1), occurring at altitudes from sea level to 1000 m. Populations morphologically similar to R. halmaheraensis have been documented from the adjacent islands of Bacan and Ternate, and are tentatively referred to here as R. halmaheraensis, but these have not yet been included in our molecular comparisons. Another allied population on Moti is known from a few specimens that are genetically (Fig. 2) and morphologically distinct from Halmaheran samples of R. halmaheraensis, indicating the need for further taxonomic study (Anang Achmadi, personal communication).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA1409FC255BA3FAF6AB70.taxon	diagnosis	Diagnosis. Rattus halmaheraensis is medium-sized rat, smaller than R. morotaiensis, with a spiny coat that is dark reddish-brown (Fig. 15). This species is characterized by: (1) a dark brown tail longer than head and body length (TL / HB = 110 – 136 %; Table 2), sparsely haired and slightly tufted at the tip (Fig. 12); (2) a distinctive spiny coat speckled with large flat spiny guard hairs; (3) a long hind foot relative to the length of the head and body; (4) the bony palate extends a moderate distance behind M 3 to form a narrow shelf; (5) the postorbital and temporal ridges are moderately developed; (6) the rostrum is narrow and its ventral side is characterized by a depression of the premaxillary bone, visible in both ventral and lateral views; (7) the zygomatic plate is moderately wide; (8) in lateral profile, the skull is arched between the nasal and occipital; (9) in ventral view, the squamosal root of the zygomatic arch is positioned at the level of the tympanic bulla; (10) in ventral view, the maxillary root of the zygomatic arch is positioned anterior to, or at, the first upper molar; (11) the incisive foramina are long and reach the anterior edge of M 1 (Fig. 7); (12) the mammae formula is 1 pectoral + 1 post-axillary + 0 abdominal + 3 inguinal (1 + 1 + 0 + 3 = 10); (13) the angular process does not extend beyond the posterior part of the articular condyle; (14) the incisor blade is very narrow, less than or equal to its longest basal width; (15) the posterior cingulum is weakly developed or absent on M 1 (Figs 9 and 13); (16) cusp t 3 is usually present on the second upper molar (in 85 % of available specimens); (17) cusp t 1 of M 1 is located just behind the level of cusps t 2 and t 3 and is well separated from the lamina in young specimens; (18) there are large peg-like anterolabial and anterolingual cuspids, subequal in size, on m 1 (Fig. 10); (19) anterolabial and posterolabial cusplets are always present on m 1; (20) the anterolabial cusplet on m 1 is as large as the anterolabial cuspid and often accompanied by a second, tiny cusplet (alc 2, Fig. 14 b); (21) a posterolingual cusplet is present in several specimens (pli, Fig. 14 a); (22) anterolabial cuspid and posterolabial cusplets are always present on m 2 and m 3 (23) the posterolabial cusplets on m 3 produce a distinct labial notch (Fig. 14 a – c, white arrows); (24) a wide cingular margin is present on m 2; (25) crenulated enamel is present on all molars. Our molecular phylogenetic results, as well as those published by Thomson et al. (2018), indicate that this species is related to R. morotaiensis and R. obiensis sp. nov., but is well differentiated genetically as well as morphologically.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA1409FC255BA3FAF6AB70.taxon	description	Description. Rattus halmaheraensis is medium-sized, with spiny fur, dorsally grizzled olive-brown mottled with reddish patches, and a long tail, 110 – 136 % of head and body length (Table 2 and Fig. 15). It is smaller in body and cranial size than R. morotaiensis. Body mass can reach approximately 250 grams. On the dorsum, the wide (0.02 mm) and long spines (10 to 16 mm long, compared to more than 20 mm long on the rump in R. morotaiensis) are pale ivory or olivegrey from base to tip, and dark brown or blackish for the distal third. There are long, soft guard hairs between these spines, which are usually bicoloured, grey proximally and reddish distally. These guard hairs are usually only slightly longer than the spines, but some can reach as long as 40 mm on the rump of the animal. The spines are channelled and convex on the underside, forming a pointed and inverted groove. The dorsum of juveniles may be slightly spiny, but they usually have a softer coat with some thin inflated spines, and the youngest individuals (e. g., MZB 33551) have moulting grey hairs. Adults and juveniles usually have a whitish belly, throat, and undersides of the legs and chin, often with some orange or rust colouring on the throat. White spines and guard hairs are usually shorter on the belly and on the undersides of the legs. Juvenile coats are usually softer with thinner white hairs, but always whitish on the belly and hind legs. The colour of the upperparts varies in the large series of specimens from Halmahera at the MZB, with young animals being darker, and older animals being paler and also having a broad brownish tinge on the throat. Mystacial, superciliary and submental, genal and interramal vibrissae adorn the head. Most of the mystacial vibrissae are dark brown or blackish with an unpigmented distal end that varies in length. The ears are of medium size (9 – 11 % of the head body length) with a dark brown or brownish tip and a buff or pale grey base. From the base to the tip, a few very short and thin buffy or silvery hairs cover the outer ear. The dorsal surfaces of the front and hind feet, including the proximal part of the digits, are covered with very short buff or brown hairs. The distal ends of the digits on the front and hind feet are covered with short silvery hairs. The nails are cream-coloured, each covered with silvery hairs that are more abundant on the hind feet. The palmar and plantar surfaces are pinkish or whitish-brown, unpigmented and hairless. The manus has two large and prominent metacarpal pads and three smaller interdigital pads. Both the interdigital and metacarpal pads are connected. Digital pads are also well developed on the digits of the fore and hind feet. On the hind feet, four interdigital pads are moderately developed. The two central interdigital pads are in close contact and both are connected to large lateral interdigital pads. The hypothenar is broad, as is the thenar. The thenar pads are long and have a broad comma shape with a distal wider base. Ulnar vibrissae are visible, mostly unpigmented but somewhat darker in three specimens. The tail is dark brown, with large square tail scales, with 8 – 9 scales per centimetre (juvenile tails have 9 – 11 scales per centimetre), and three hairs per scale, each slightly longer than a scale. A small tuft of dark hairs is present at the tip of the tail, but this is not as strongly developed as in R. feileri (Fig. 12). Females usually have 10 functional teats with 1 pectoral, 1 post-axillary and 3 inguinal pairs. The skull of R. halmaheraensis is smaller than in R. morotaiensis (Figs 6 – 8). It has a short and narrow rostrum with a weakly developed lacrimal groove. The frontal and postorbital ridges are present in adults but not in juveniles (Fig. 16 and Fig. 19); these ridges are less pronounced overall, and less developed in immature specimens, than in R. morotaiensis (Figs 6, 18, 19). In lateral profile the top of the skull curves from nasal to occipital, a distinctive feature compared to R. morotaiensis. In R. halmaheraensis the braincase is smaller with a more rounded shape and an antero-posteriorly reduced interparietal bone than in R. morotaiensis. A distinctive feature of R. halmaheraensis is its very narrow rostrum, with a diagnostic premaxillary constriction, most visible from the ventral side (Fig. 7). In ventral view, the incisive foramina of R. halmaheraensis are longer than in R. morotaiensis, slightly overlapping the anterior surface of the first upper molars (Fig. 7). The palatal bridge in R. halmaheraensis does not extend as far behind the third molars as in R. morotaiensis. In R. halmaheraensis, the maxillary root of the zygomatic arch reaches the first upper molar, and the squamosal root of the zygomatic arch reaches the level of the tympanic bulla. The upper incisors of R. halmaheraensis are more gracile and less opisthodont than in R. morotaiensis.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFA1409FC255BA3FAF6AB70.taxon	discussion	The dentition of R. halmaheraensis is very distinctive. The upper and lower molar rows are proportionally smaller relative to the skull size compared to R. morotaiensis (Figs 7, 13 – 14). The strongly crenulated enamel, molar cusp patterns, and shape of the laminae are similar in size to R. morotaiensis, though the antero-posterior decrease from M 1 to M 3 is more pronounced in R. halmaheraensis (Figs 13 – 14). Cusp t 3 is usually present on M 2 (85 % of specimens) and M 3 (75 % of specimens). The most distinctive upper molar features of R. halmaheraensis are (1) a smaller cusp t 1 on M 1, placed more ventrolaterally to the t 2 + t 3 lamina compared to R. morotaiensis, and (2) cusps t 2 and t 3 of M 1, which are fused into a distinctive, straight lamina compared to the more tuberculate lamina of R. morotaiensis (Fig. 13). The anterolabial cuspid and posterolabial cusplet are always present on m 1 and m 2 and also on m 3. Unlike R. morotaiensis, this posterolabial cusplet forms a distinct notch on the hypoconid of m 3 (Fig. 14; white arrows). The most distinctive feature of the m 1 of R. halmaheraensis is an anterolabial cusplet which is as large as the anterolabial cuspid and often followed by a second tiny cusplet (alc 2, Fig. 14 b). An unusual posterolingual cusplet is also present in several specimens (pli, Fig. 14 a). All specimens show strongly crenulated enamel ridging, which is unique to R. halmaheraensis and R. morotaiensis within Rattus.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFF1435FC585A8BFE74AD24.taxon	description	urn: lsid: zoobank. org: act: A 93 D 2 EEF-EC 57 - 4161 - A 9 F 2 - 6 E 992 F 6 B 069 B Figs 6 h, 7 h, 8 h, 9 h, 10 h, 13 d, e, 14 d, e, 15 c, f, 16 c, 20	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFF1435FC585A8BFE74AD24.taxon	materials_examined	Holotype. The holotype (in the Museum Zoologicum Bogoriense, Cibinong MZB 38231) is a juvenile female (Fig. 20) (study skin, cleaned skull, postcranial skeleton, and tissue sample in ethanol) collected by P. - H. Fabre on 27 November 2013 with a live rat-trap baited with coconut and peanut butter. The dentition is fully erupted, the sutures on the skull are not fully closed, and the woolly coat is in immature pelage. Paratype. A paratype (MZB 38232) was also collected by P. - H. Fabre on 28 November 2013. It is a juvenile female (study skin, cleaned skull, postcranial skeleton, and tissue sample in ethanol). Type locality. The type locality, in the southwest of the island of Obi (North Maluku Province, Indonesia), is on Gunung Sere above the villages of Tapaya and Wayaloar. The holotype was collected along a ridge at 970 m asl, near a campsite at 1.624 ° S 127.709 ° E, 870 m asl. The trapping site sits in disturbed secondary forest that was logged less than 20 – 25 years ago, as explained by the local community (Pak Sabar, personal communication).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFF1435FC585A8BFE74AD24.taxon	etymology	Etymology. This species is named after the island of Obi, where the type locality is situated.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFF1435FC585A8BFE74AD24.taxon	distribution	Distribution. Rattus obiensis is endemic to Obi Island, Maluku, Indonesia and has only been recorded at the type locality. The species may be more abundant at higher altitudes, as we did not catch it during 8 nights with 200 rat traps at a lower altitude camp (40 – 70 m) in the northern part of Obi Island; it was also not encountered by Tim Flannery during mammal surveys at low elevations in Obi and Bisa in January 1990 (Flannery, 1995).	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFF1435FC585A8BFE74AD24.taxon	diagnosis	Diagnosis. As we only have two immature specimens, we focus our diagnosis on a selected set of external and cranio-mandibular characters stable across both adults and juveniles of Rattus. These consist especially of occlusal features of the molars. The molars of our specimens are fully erupted and very distinctive compared to other Moluccan Rattus. Even though we only have immature specimens, it is clear that, when grown, this new species would be a smaller animal than R. morotaiensis and R. halmaheraensis, the other members of the Rattus morotaiensis group. Rattus obiensis is a small rat with broad spiny hairs, characterized by the following features: (1) a long dark tail, which is longer than the head and body length (TL / HB = 128 – 130 %; see also Table 2; Fig. 15 and Fig. 20); (2) long hind feet in proportion to the head and body length; (3) the palatal bridge extends slightly beyond M 3 (Fig. 16); (4) a broad zygomatic arch that curves posteriorly outwards (Fig. 4); (5) the zygomatic plate is reduced and the rostrum is short and narrow; (6) in ventral view the squamosal root of the zygomatic arch does not overlap the level of the tympanic bulla; (7) in ventral view the zygomatic root of the zygomatic arch slightly overlaps at the level of the first upper molar; (8) the eustachian tube is slightly developed; (9) the short incisive foramina reach the first upper molar posteriorly; (10) the upper incisors are orthodont in configuration, with orange enamel faces, and have a distinct notch; (11) the incisor blade is narrow, less than or equal to its longest basal width; (12) a well developed posterior cingulum is present on M 1 (Fig. 13); (13) cusp t 3 is present on M 2 (and variably present on M 3); (14) on M 1, cusps t 1 and t 4 are situated well posterior to the first (cusps t 2 and t 3) and second laminae (cusps t 5 and t 6), respectively; (15) large, peg-shaped anterolabial and anterolingual cuspids, subequal in size, are present on m 1 (Fig. 14); (16) a poorly developed anterolabial cusplet is present on m 1; (17) an anterolabial cuspid is present on m 2 and m 3; (18) posterolabial cusplets are present on all lower molars; (19) the posterolabial cusplet on m 3 is distinct and produces a labial notch (Fig. 14 d – e; white arrows); (20) the posterior cingulum is present and well developed on m 1 and m 2; (21) crenulated enamel is present but relatively poorly developed. The mammae formula is as yet unknown. Our morphological results indicate that this species is closely related to R. morotaiensis and especially R. halmaheraensis but is well differentiated genetically.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFF1435FC585A8BFE74AD24.taxon	description	Description and comparison with immature Rattus halmaheraensis. Within the genus Rattus, R. obiensis is a distinctive lineage in its molecular phylogenetic divergence (Table 1 and Fig. 2), as well as in terms of body proportions and cranio-mandibular and dental characters. We captured two immature animals during our fieldwork on Obi Island but were unable to obtain any adults. Given the difficulty of accessing these islands and the significant human activity, we describe this new species here on the basis of these two specimens. Among semi-arboreal Rattus species, R. obiensis has the longest tail, which is 128 – 130 % of head-body length (Table 2). The tail is covered with short squarish scales that are much smaller than those found on R. halmaheraensis of similar age. Because they are immature, the fur of these specimens is greyish with a woolly undercoat, but is beginning to show some adult features, including flat spiny hairs and some longer brownish guard hairs. On the dorsum the hairs are soft, buff and grey. The guard hairs are bicoloured, with bases that are whitish grey and tips that are golden brown, buff, or greyish brown as in R. halmaheraensis of the same age. Some of the guard hairs are thickened and ivory coloured. The dorsal fur is darkest, becoming paler along the mid-line of the body, where the dorsum meets the venter, and here the guard hairs are whitish brown or yellowish brown. The cheeks are greyish. The belly is whitish grey, and one of the two specimens has a white pectoral patch. On the mid-belly, yellowish or golden brown hairs mix with the grey hairs. The undersides of the legs are whitish grey. Compared to immature specimens of R. halmaheraensis, R. obiensis is much smaller, has a paler coat, and has a longer tail with more hairs at the tip (though not so developed as the pencillate tail tip of R. feileri; Fig. 12). In addition, its coat is woollier, and its belly is covered with grey fur, a characteristic not observed even in very young individuals of R. halmaheraensis. Young R. halmaheraensis usually have less woolly and darker dorsal fur, with a paler white belly. The skull of R. obiensis has a short and narrow rostrum with a narrow lacrimal region (Fig. 16). Rattus obiensis has a similar dorsal cranial shape in lateral view compared to R. halmaheraensis but is significantly smaller in size compared to juveniles or subadults of that species. Compared to R. halmaheraensis juveniles, it has a proportionally larger braincase, a narrower orbit, and a narrower interparietal region that is closely attached to the margin of the nuchal crest. The upper incisors are orthodont and both upper incisors have a prominent notch, seen in both specimens. The upper incisors are very narrow compared to R. halmaheraensis of similar age. In lateral view, the zygomatic arch sits at the level of the upper molar row and its squamosal root lies well in front of the post-glenoid process. The incisive foramina are proportionally larger than in immature specimens of R. halmaheraensis. The upper molars are proportionally smaller than in R. halmaheraensis. The tympanic bullae and braincase are proportionally similar to those of R. halmaheraensis, but R. obiensis has a distinctly larger and longer eustachian tube. The mandible of R. obiensis is wider and higher, with a narrower but longer angular process than in R. halmaheraensis of similar age.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
11517770FFFF1435FC585A8BFE74AD24.taxon	discussion	The upper molars are very small in R. obiensis and have a distinctive laminar pattern compared to all other Moluccan and Indo-Pacific Rattus (Figs 13 – 14). The laminae on the upper molars are oblique, with cusp t 1 situated well behind cusps t 2 + t 3 on the first lamina, and cusp t 4 situated well behind cusps t 5 + t 6 on the second lamina. Thus, the third, posterior lamina (cusps t 8 and t 9) appears anteriorly surrounded by the second lamina (cusps t 4, t 5 and t 6). A similar pattern is observed on M 2. This configuration is distinctive compared to all Maluku, Sulawesi, and Australo-Papuan Rattus (Musser & Holden, 1991; Taylor & Horner, 1973; Taylor et al., 1982). Compared to juveniles of R. halmaheraensis, R. obiensis has narrower laminae. In contrast to the condition in R. morotaiensis and R. halmaheraensis, R. obiensis has less developed enamel crenulation, similar to the extent of crenulation in some other Rattus species (e. g., R. leucopus). On M 1, the posterior cingulum is well developed, and cusps t 8 and t 9 are proportionally reduced, compared to R. halmaheraensis. Cusp t 3 is present on M 2 in both specimens, but variable on M 3 in the two available specimens (Fig. 13 d – e). The lower molars are very small, with a cusp pattern very similar to R. halmaheraensis in several key aspects. First, m 1 has large peg-like anterolabial and posterolabial cuspids. Second, m 2 has an anterolabial cuspid and posterolabial cusplets. Third, m 3 has a well differentiated posterolabial cusplet, a diagnostic feature of both R. obiensis and R. halmaheraensis compared to R. morotaiensis and other Rattus from the region. Anterolabial cuspids on m 3, present in R. morotaiensis but only in a minority of specimens of R. halmaheraensis, are present in both specimens of R. obiensis.	en	Fabre, Pierre-Henri, Miguez, Roberto Portela, Holden, Mary Ellen, Fitriana, Yuli S., Semiadi, Gono, Musser, Guy G., Helgen, Kristofer M. (2023): Review of Moluccan Rattus (Rodentia: Muridae) with Description of Four New Species. Records of the Australian Museum 75 (5): 673-718, DOI: 10.3853/j.2201-4349.75.2023.1783
