Euryoryzomys cerqueirai Percequillo & Weksler, 2023

Percequillo, Alexandre Reis & Weksler, Marcelo, 2023, Systematics of the genus Euryoryzomys Weksler et al., 2006 (Rodentia: Cricetidae): integrative analysis reveals a new species from north-eastern Brazil, Zoological Journal of the Linnean Society 199 (3), pp. 594-632 : 607-615

Euryoryzomys cerqueirai Percequillo & Weksler , sp. nov.

Oryzomys lamia : Dobbin et al. 1969: 749. Guimarães (1972) 116; part.

Oryzomys sp. :: 117.

Oryzomys sp. : Paiva 1973: 446. Paiva 1974: 197.

Oryzomys lamico : Santana et al. 1991: 417 incorrect spelling. Oryzomys sp. n.: Silva et al. 2000: 220.

Zoobank registration: This nomenclatural act is registered in ZooBank: urn:lsid:zoobank.org:act:BD0F9811-F36A-44BA-AB0B-C418457507A3

Type locality: Brazil, Ceará State, Municipality of Pacoti, Serra de Baturité , Sítio Friburgo , Grota do Bananal , c. 1.5 km from ranch’s headquarters; geographic coordinates 4°14ʹ19ʹʹS, 38°54ʹ00ʹʹW .

Holotype: MZUSP 36044 , an adult male specimen collected by Alexandre Reis Percequillo and Maria José de Jesus Silva (original field MTR130) on 10 October 1998. The holotype consists of skull and skin, with dried phallus ( Figs 9–11 ). Bone marrow cells suspension in Carnoy’s fixative (methanol: acetic acid) and a liver tissue sample preserved in ethanol are housed at Coleção de Tecidos de Répteis e Anfíbios do Departamento de Zoologia (MTR), Instituto de Biociências da Universidade de São Paulo, under the original field number MTR130. Cytochrome b DNA data were deposited in GenBank (accession number ON815481 ).

Paratypes: Brazil, Ceará State, Municipality of Pacoti, Serra de Baturité, área do IBAMA: MZUSP 36040 (MRT015) and 36041 (MRT027); Municipality of Pacoti, Serra de Baturité , Sítio Friburgo : MZUSP 36042 (MRT046) and 36043 (MRT048); Municipality of Pacoti, Pacoti , Mata da Sede do Museu de História Natural do Ceará Prof. Dias da Rocha : MHNCE 236 (ACA58), 241 (ACA72), 248 (ACA114), 251 (ACA117), 257 (ACA123). Municipality of Guaramiranga, Serra de Baturité , Sítio Sinimbú : MN 91065 (CRB3661), 91066 (CRB3687), 91067 (CRB3688), and 91068 (CRB3689); all specimens preserved as skin, skull, and tissue; MZUSP specimens also have body in fluid and bone marrow cells suspension, while MN specimens also have complete skeletons.

Etymology: This species is named in honour of Dr. Rui Cerqueira ( Fig. 12 ), Full Professor at the Universidade Federal do Rio de Janeiro, to celebrate his friendship, his long and productive career as a professor, scientist, and mentor, and his remarkable role on the development of Brazilian Mammalogy, being the first president of the Sociedade Brasileira de Mastozoologia (SBMz; Brazilian Mammalogy Society) and honorary member of the American Society of Mammalogists.

Geographic distribution: Euryoryzomys cerqueirai is known from 19 localities in the Brejos de altitude of north-eastern Brazil ( Figs 1 , 13 ). In the state of Ceará, the species was collected in the municipalities of São Benedito , Guaraciaba do Norte , Ibiapina , Guaramiranga , and Pacoti ; the first three sampling sites are located at the Ibiapaba Plateau , a mountain range with a northsouth orientation on the western portion of the state of Ceará near the limits with Piauí state, that is nearly perpendicular to the Brazilian northern coast, and reaches approximately 900 m a.s.l. The last two collecting municipalities are from Serra de Baturité , another mountain range with the same orientation of Serra da Ibiapaba , but on the central portion of Ceará. One record is tentatively assigned to Paraíba, corresponding to the specimen from Mata do Pau Ferro , Municipality of Areia (see above). This collecting locality is also located in a mountain range, although lower (about 600 m in elevation), parallel to the Brazilian north-eastern coast.

Diagnosis: Euryoryzomys cerqueirai can be differentiated from the rest of the species of the genus by the combination of the following characters: overall dorsal pelage ochraceous-yellow to ochraceous-tawny, thinly and intensely grizzled with brown; dorsum with diffuse and wide darker stripe, with flanks gradually turning into ochraceous-orange with final ochraceous-buff lateral line; long tail, distinctively bicoloured; ungual tusss dense and long, surpassing the length of claws; skull with supraorbital margins weakly divergent posteriorly and with small and delicate dorsolateral crest; jugal present; incisive foramina long with convex lateral margins; anterior portion of alisphenoid concave, not projected anteriorly; posterolateral palatal pits small and multiple, recessed or not in shallow palatine depressions; mastoid with small fenestra; M2 with parafosseưe, or with parafosseưe and mesofosseưe; M2 with distinct anterolabial cingulum; diploid number of 76 chromosomes and fundamental number of 86.

Morphological description: Head and body length range: 105 mm to 152 mm (126.5 ± 10.4; N = 21); tail length: 130 mm to 170 mm (150.2 ± 11.6; N = 20); hindfoot length: 29 mm to 35 mm (31.2 ± 1.95; N = 21); ear length: 22 mm to 27 mm (23.9 ± 1.36; N = 21); body mass: 42 g to 100 g (62.1 ± 13.11; N = 20).

Dorsal pelage ( Fig. 9 ) is long, dense, and lax, with homogeneous structure. Wool hairs, or villiforms, very thin and short, weakly wavy, ranging from 10 mm to 11 mm; basal portion of wool hairs greyish, and distal portion, approximately 2 mm in length, with three bands, basal brown, subterminal buffy yellowish, and terminal dark-brown coloured. Cover hairs, or setiforms, longer and thicker than wool hairs, ranging from 12 mm to 14 mm; basal two-thirds greyish and distal third, nearly 5 mm in length, with different paưerns: on dorsal region, hairs with three bands, basal brown, subterminal ochraceous-yellow (buckthorn brown in Ridgway 1912) or ochraceous-orange, and terminal dark-brown coloured, and hairs with one dark brown terminal band; on lateral region, hairs with one terminal light ochraceous-yellow or ochraceous-orange band, and hairs with a basal brown band and a distal whitish-yellow band. Aristiforms, or guard hairs, very long and wide, ranging from 16 mm to 17 mm in length; in the dorsal region, the basal half of aristiforms is greyish while the distal half is dark brown, with golden or whitish apex; in the flanks, aristiforms are less frequent than in dorsal region, with basal half greyish and distal half with two bands, the proximal light brown, and the terminal yellowish white. Overall dorsal body colour ochraceous-yellow to ochraceous-tawny, thinly and intensely grizzled with brown, and with diffuse and wide darker stripe on the dorsal region, more clearly delimited in Ibiapaba Range specimens; flanks more intense ochraceous-yellow to ochraceous orange, weakly grizzled with light brown, gradually turning into ochraceous buff lateral line; dorsal and lateral pelage clearly distinct from ventral pelage. Ventral pelage soss, dense, and short. In the venter, villiforms are short, ranging from 4 mm to 5 mm in length, while setiforms are long, ranging from 6 mm to 8 mm, and aristiforms are less frequent, with 9 mm to 10 mm in length. Villiform, setiform, and aristiform hairs with basal portion (2 mm to 3 mm) greyish and distal portion white (depigmented), except on gular and inguinal regions, with hairs almost entirely white. Ventral body colour greyish-white, with predominantly white areas on gular and inguinal regions; mental and genital regions white, with entirely white hairs. Head pelage shorter than dorsal (villiforms— 7 mm; setiforms— 9 mm; aristiforms— 10 mm), with few aristiform hairs; dorsal head colour greyish-brown, weakly grizzled with light yellow; mystacial region ochraceous-yellow or whitish. Young individuals with coarser and shorter pelage and with darker dorsal colour, greyish brown, weakly grizzled with ochraceous or yellow; ventral pelage predominantly greyish. Pinnae covered both internally and externally with short hairs; internally, hairs with basal brown band and golden-yellow terminal band; externally, hairs almost entirely dark brown, with golden tip. Tail longer than head and body length in adult specimens (HBL: 123.3 ± 8.6, N = 15; TL: 145.8 ± 9.3, N = 14; t = 6.749; d.f. = 27; P <0.0001). Tail scales small, barely visible to the naked eye; scales with three hairs, the central one longer than the lateral ones, with length equivalent to two and a half rows of scales, but tail apparently naked to bare eye; distal portion of tail with longer hairs, with length equivalent to three rows of scales; tail bicoloured dorsoventrally, with brown dorsal scales and hairs, and unpigmented (white) ventral scales and hairs through almost the entire length of tail, except for the apical portion, where some hairs exhibit a brown basal segment and unpigmented (white) apical segment. Manus and pes with dorsal surface covered by short white hairs; digits with hairs longer than dorsal surface; ungual tusss very long and dense, exceeding the length of claws. Ventral surface of manus and pes predominantly smooth, with squamae between interdigital pads; manus with three interdigital pads and two palmar, thenar and hypothenar, fleshy; pes with four interdigital pads and two plantar pads, thenar and hypothenar, large and fleshy; entire ventral surface flesh buffy to light brown. Mystacial vibrissae are long, but do not surpass ears when laid back; vibrissae brown, with golden apex.

Skull small and delicate for the genus ( Figs 10 , 11 ), with total length ranging from 30.73 mm to 35.88 mm (NOL: 33.31 ± 1.32; N = 22). Rostrum long and narrow, ranging from 4.92 mm to 5.87 mm (BR: 5.53 ± 0.22; N = 21); nasolacrimal foramina not inflated, with narrow and slit-like opening; rostral fossa shallow, without any depression on premaxilla and maxilla; zygomatic notch narrow and medium-deep. Interorbital region narrow anteriorly, slightly divergent posteriorly; supraorbital margins with small and delicate dorso-lateral bead, that extends posteriorly on the dorso-lateral margin of braincase, forming a squared to slightly beaded temporal ridge; temporal ridge extending to lambdoidal crest; lambdoidal crest sharp, but not very developed; nuchal crest weakly developed; braincase elongated.

Gnathic process small, barely surpassing the anterior surface of upper incisors; zygomatic plate (in lateral view) low and narrow, ranging from 3.31 mm to 4.45 mm (LPZ: 3.89 ± 0.28 mm, N = 22), with anterior margin slightly concave and free dorsal margin moderately long and rounded. Zygomatic arches are narrow and delicate, diverging posteriorly; arches wider posteriorly, near the squamosal root; jugal present, small in some individuals. Anterior margin and lateral surface of alisphenoid concave, without an anteriorly projected lamina; sphenofrontal foramen opening on the external surface of alisphenoid, on the suture with the orbitosphenoid; alisphenoid strut usually absent, but present unilaterally in a few individuals (N = 3). Stapedial foramen, squamosal–alisphenoid groove, and sphenofrontal foramen are present, configuring the carotid circulatory pattern 1 ( Voss 1988). Postorbital crest absent. Tegmen tympani small and laminar, sometimes absent; posterior suspensory process of squamosal absent; tegmen not reaching or overlapping the squamosal, configuring a postglenoid foramen moderate to large; postglenoid foramen separated from the small and narrow subesquamosal fenestra by a narrow and long hamular process of squamosal. Ectotympanic stapedial process usually very short, not reaching the alisphenoid; dorso-stapedial process absent. Auditory bulla with large external auditory meatus; mastoid oval, with rounded surface; mastoid fenestra usually present.

Incisive foramina moderately long, ranging from 4.87 mm to 6.35 mm (LIF: 5.51 ± 0.42 mm; N = 22), and narrow, ranging from 1.98 mm to 2.34 mm (BIF: 2.14 ± 0.10 mm; N = 22), not reaching plane of M1 alveoli; incisive foramina larger medially and with lateral margins convex (lenticular shape), with posterior margins distant from alveolus of upper molar series. Bony palate long and wide, not excavated; posterolateral palatal pits small and multiple, recessed or not in shallow palatine depressions; palatal excrescences absent; mesopterygoid fossa not penetrating between molar series; anterior margin of fossa rounded to slightly squared; fossa with the same width as lateral parapterygoid plates; roof of mesopterygoid fossa totally ossified or perforated by two very small and narrow sphenopalatine vacuities, situated around the presphenoid–basisphenoid suture. Parapterygoid plate shallow, not excavated; plate separated from the palate by the posterolateral palatal pits; plate perforated by several nutritive foramina. Transverse channel small. Posterior opening of alisphenoid channel large, with a well-delimited posterior groove; channel confluent with medium lacerate foramen in some specimens. Medium lacerate foramina wide. Auditory bulla small, not globose or inflate; Eustachian tube short and narrow; carotid canal small, variably bordered by the ectotympanic and basioccipital or only by the ectotympanic.

Mandible shallow ( Fig. 11 ), with coronoid process weakly falciform, nearly triangular, lower than the condyloid process; superior and inferior notches slightly concave and shallow; angular process rounded, aligned with the condyloid process. Capsular process of lower incisor well developed, positioned between coronoid and condyloid processes; in a few specimens, the capsular process positioned immediately posterior to coronoid process. Upper and lower masseteric crests weakly developed, never forming a unique anterior crest.

Upper incisors narrow, opisthodont; anterior enamel band orange. Upper molar series parallel, with moderate length ranging from 4.46 mm to 5.07 mm (LM: 4.8 ± 0.16 mm, N = 21) and small width ranging from 1.41 mm to 1.59 mm (BM1: 1.5 ± 0.05 mm, N = 22). Molar toothrows ( Fig. 11 ) parallel; labial and lingual flexi of upper molars shallowly penetrating at molar midline; labial and lingual main cusps arranged in opposite pairs, low crowned. First upper molar (M1) with undivided anterocone; anteroloph developed and fused with anterostyle on labial cingulum, separated from anterocone by persistent anteroflexus; protostyle absent; paracone connected by enamel bridge to protocone posteromedially (median mure), and also connected (in some specimens) to protocone by an enamel bridge medial to paraflexus, configuring (with moderate tooth wear) two enamel islands, the mesofosseưe and the parafosseưe; mesoloph well developed, long, connected to distinct mesostyle on labial margin of molar; second upper molar (M2) with small anterolabial cingulum; paracone connected by enamel bridge to protocone posteromedially (median mure), and also connected (in most specimens) to protocone by a enamel bridge medial to paraflexus, configuring (with moderate tooth wear) two enamel islands, the mesofosseưe and the parafosseưe (in some specimens, a second enamel bridge connects the paracone and protocone medially to paraflexus, configuring a third enamel island); mesoloph well developed, long, connected to distinct mesostyle on labial margin of molar; third upper molar (M3) with mesoloph, posteroloph, and hypoflexus barely discernible; paracone and protocone distinguishable on molar surface, hypocone reduced and metacone greatly reduced and completely fused with posteroloph. First lower molar (m1) not divided by anteromedian flexid; second lower molar (m2) has distinct ectostylid or even a narrow and delicate ectolophid; lower third molar (m3) greatly reduced. First upper molar with three main roots, anterior and posterior labial and lingual, and an accessory rootlet, between the two labials and beneath the paracone; second and third upper molars with three main roots; lower molars with two roots, at anterior and posterior positions.

Tuberculum of first rib articulates with transverse processes of seventh cervical and first thoracic vertebrae; second thoracic vertebra with differentially elongated neural spine; thoracicolumbar vertebrae 19, the 17th with moderately developed anapophyses; sacrals 4; caudals 32–34, with complete hemal arches in the first four; ribs 12; entepicondylar foramen of humerus absent; supratrochlear foramen of humerus present.

Phallus with urethral ventral papilla developed, compressed dorso-ventrally. Bony baculum with basal portion wide, spatulate, concave medially and compressed dorso-ventrally, gradually tapering distally; cartilaginous distal baculum tridigitate; all digits with cylindrical transversal section; central digit longer than lateral ones ( Fig. 14 ).

1.350

1.275

1.200

1.125

1.050

0.975

0.900

0.825

E. legatus E. russatus E. macconnelli E. nitidus E. lamia Euryoryzomys sp. E . emmonsae

Karyotype: The diploid number of E. cerqueirai is 2 n = 76, and the FN = 86, as reported in specimens from Pacoti ( Silva et al. 2000; see also: Moreira et al. 2020) in Serra de Baturité.

Natural history: Euryoryzomys cerqueirai dwells in the humid evergreen or semi-deciduous forests ( Hueck 1972) found in the upper portions of the mountains of Serra de Ibiapaba, Serra do Baturité in Ceará, and possibly in Areia in Paraíba. These montane humid forests, restricted to upper portions of mountains and serras from north-eastern Brazil, are locally known as Brejos de altitude ( Fig. 13 ) and are very distinct from the drier deciduous forest that covers the lower lowlands and the lower slopes of these ranges; orographic rain and mist are responsible for the establishment of these humid enclaves amidst the predominantly drier surroundings, occupied by typical Caatinga landscapes ( Ab’Sáber 2003).

Euryoryzomys cerqueirai is sympatric with Cerradomys langguthi , but these species are rarely syntopic; the former is predominantly associated with forested habitats, while the laưer is more frequently found in drier transitional forests, secondary forests and grassy habitats in the Serra da Ibiapaba [according to the files of Serviço Nacional de Peste, SNP (National Plague Office), available at the archives of Museu Nacional, Rio de Janeiro; Oliveira and Franco 2005]. While sorting specimens from the extensive series of Oryzomyini species of the Serviço Nacional de Peste from north-eastern Brazil, mostly from localities of typical drier Caatinga habitats from the states of Alagoas, Pernambuco, and Ceará, we were unable to find any specimen of E. cerqueirai apart from those collected in the forested habitats in São Benedito, Guaraciaba do Norte and Ibiapina; by contrast, specimens of C. langguthi were fairly abundant in most localities. The same paưern was observed on the SUCAM series from transitional areas between coastal Atlantic Forest, Brejos de altitude and Caatinga in the states of Paraíba and Pernambuco obtained during the 1980s and 1990s, housed at the Universidade Federal da Paraíba.

Specimens from Pacoti, Serra de Baturité, were captured in Brejos de altitude, in forested habitats from 700 m to 1050 m of elevation, in areas with dense leafliưer and lianas, and also in areas with native forest mixed with coffee and banana plantations; in contrast to Serra da Ibiapaba, we captured C. langguthi (six specimens) along the same traplines. In this area, we also sampled Marmosa murina (21 specimens), Marmosa (Micoureus) sp. (six specimens), Monodelphis americana (11 specimens), Monodelphis domestica (one individual), Necromys lasiurus (five specimens), Oligoryzomys sp. (seven specimens), and Rhipidomys baturitensis (two specimens). Similarly, in Guaramiranga, also in Serra de Baturité, E. cerqueirai was trapped in forested habitats above 800 m of elevation, in the same traplines as C. langguthi (two specimens), Necromys lasiurus (two specimens), Thrichomys laurentius (two specimens), Oecomys catherinae (two specimens), Marmosa murina (one specimen), and Holochilus sp. (one specimen).

Guimarães (1972) studied the ectoparasites of several species of sigmodontine rodents collected in north-eastern Brazil by the Serviço Nacional de Peste (SNP), amongst them Oryzomys sp. , that we believe represents the new species described here. The specimens were collected in São Benedito e Guaraciaba do Norte, in Ceará, and host three or four flea species: Craneopsylla minerva minerva , Polygenis bohlsi jordani , Polygenis tripopsis , and, possibly, females of Polygenis roberti . The author was not completely certain about the identity of this last form because the females of the three species of genus Polygenis ( P. roberti , P. beebei , and P. tripopsis ) are nearly indistinguishable ( Guimarães 1972: 107). These species of fleas are not exclusive to a certain host species, being shared with other rodent species, including Cerradomys langguthi . This species hosts a much greater diversity of fleas, probably related to its much wider geographic

distribution throughout north-eastern Brazil and also to the substantially larger series of this species available for study ( Guimarães 1972).

Conservation status: This species, as far as we known, inhabits three relatively small forest remnants in Brejos de altitude within the Caatinga Biome. These mountainous areas are moderately threatened by human activities, such as agriculture and urban expansion, but are not adequate for extensive farming. Instead, they are used for shaded coffee and banana plantations, which are grown amidst the forest; in addition, as these mountains areas are weưer and colder, they have an important touristic appeal, being considered as an oasis within the Caatinga and locally called the ‘Ceará’s Switzerland’ (at least, in Serra de Baturité). Thus, the environment is apparently not under serious threat, which is positive for the conservation of this species.

During the survey conducted in Pacoti in 1998, five specimens of E. cerqueirai were collected among 64 specimens of small nonvolant mammals (7.8%), a relatively low abundance when compared to Marmosa murina , the most abundant species, with 21 specimens (32.8%) and Monodelphis americana , with 11 individuals (17.2%); the most abundant rodent was Oligoryzomys sp. , with 11%, and the least was Rhipidomys baturitensis , with 3.1%. During the survey in Guaramiranga in 2015, eight specimens of E. cerqueirai were collected. The species is not uncommon in this sampling site, which together with the fact that the environment is not being severely affected, suggests that the species might not be threatened, but no data are available for population viability or demographic fluctuations, and no recent data are available from Serra de Ibiapaba. We propose that the species be categorized as data deficient until further information is acquired and before a proper evaluation by IUCN criteria.

Remarks: Dobbin et al. (1969) employed the name Oryzomys lamia (currently Euryoryzomys lamia ) to a rodent that was the host species of fleas from São Benedito, in the Ibiapaba Plateau, Ceará, obtained by the Serviço Nacional de Peste (SNP). Unfortunately, Dobbin et al. (1969) did not provide voucher numbers, but SNP specimens housed in the MN mammal collection ( Oliveira and Franco 2005) that were originally identified as Oryzomys lamia in their specimen labels are, in fact, E. cerqueirai . Other examined ‘ex- Oryzomys’ ( Weksler et al. 2006) specimens from São Benedito and Guaraciaba do Norte municipalities in the Ibiapaba Plateau pertained to Cerradomys langguthi (see also: Percequillo et al. 2008) and Oecomys catherinae (see also: Saldanha and Rossi 2021). Material identified as Oryzomys sp. by Guimarães (1972) and Paiva (1973, 1974) and Oryzomys lamico [sic] by Santana et al. (1991) also lack voucher numbers, but we believe they are similarly derived from the same SNP sample.

Specimens examined: BÞSIL: CEARÁ: Guaraciaba do Norte: Sítio Rua Nova: M, MN 42508, skin and skull; F, MN 37048, skin and skull. Sítio São José: M, MN 42930, skin and skull; F, MN 37050 42507 44834 44835, skin and skull. Sítio Tomé: M, MN 37051 37053, skin and skull. Sítio Guarrancho: F, MN 37047, skin and skull. Sítio Cacimba do Meio: M, MN 42509, skin and skull; F, MN 37052, skin and skull. Sítio Benedito: M, MN 42933, skin and skull. Sítio São Tomé: M, MN 42931 42932, skin and skull. Sítio Convento: F, MN 44836, skin and skull. Ibiapina: Sítio Colorelo: F, MN 44837, skin and skull. São Benedito: Sítio Pimenteira: M, MN 37049 44840, skin and skull. Sítio Cabeceira: F, MN 37044, skin and skull. Sítio Queimadas dos Martins: M, MN 37046 44839, skin and skull. Sítio Carangueijo do Pereira: M, MN 37045, skin and skull; F, MN 44842 44843, skin and skull. Sítio Barra: M, MN 42934, skin and skull; F, MN 44842, skin and skull. Pacoti: Serra de Baturité, área do IBAMA: M, MZUSP 36040–1; Serra de Baturité, Sítio Friburgo: M, MZUSP 36042–4, skin, skull, tissue, body in fluid, karyotype; Pacoti, Mata da Sede do Museu de História Natural do Ceará Prof. Dias da Rocha: F: MHNCE 248, skin and skull; M: MHNCE 236 251, skin and skull; I: MHNCE 241 257, skin and skull. Guaramiranga: Sítio Sinimbú: F: MN 91066, CRB 3700, skin, skull, skeleton, and tissue; M: MN 91065, 91067–8, CRB 3663 3686 3698, skin, skull, skeleton, and tissue. PAÞÍBA: Areia: Mata do Pau Ferro, 6 km Areia: M: UFPB 2064.

Figures

Figure 1. Map of collecting localities of geographic samples of seven species of genus Euryoryzomys, based on the gazeưeer provided in Appendix I.

Figure 9. Dorsal and ventral views of the skins of two male specimens of Euryoryzomys sp. nov. from Serra de Baturité, Ceará, Brazil.From less to right, MZUSP 36044 (MRT 130); and MZUSP 36042 (MRT 46); external measurements are, respectively, HBL: 136 mm, TL: 167 mm; and HBL:136 mm, TL: 159 mm.

Figure 10. Comparative plate of Euryoryzomys skulls, showing the variation of three selected qualitative traits, the presence of jugal (lateral view; A-E), depth of the zygomatic notch (dorsal view; F-H), and the shape of incisive foramina (ventral view; I-L). (A) E. russatus, MN81475; (B) Euryoryzomys sp. nov. CRB3688; (C) E. lamia, MN67090; (D) E.lamia, CRB1024; (E) Euryoryzomys sp. nov.MN37046. (F) E. russatus, MN81475; (G) E. lamia, MN67090; (H) Euryoryzomys sp. nov., MN37046. (I) Euryoryzomys sp. nov., CRB3688; (J) E.lamia, MN67090; (K) E. russatus, MN81475; (L) E. macconnelli, MN56817.

Figure 11. Dorsal, ventral and lateral views of the skull of specimen MZUSP 36044, male, the holotype of the new species of Euryoryzomys cerqueirai sp. nov., from Serra de Baturité, Ceará, Brazil.TOL = 35.11 mm.

Figure 12. Prof.Dr.Rui Cerqueira at the VII Congresso Brasileiro de Mastozoologia, in Gramado, Rio Grande do Sul, Brazil, in 2014; in this congress, Rui received an award by the Sociedade Brasileira de Mastozoologia (SBMz) in recognition for his contribution to mammalogy; note that he is wearing the medal awarded to him by the American Society of Mammalogists in 2012 as honorary member. Photo by Ana Lazar.

Figure 13. Known collection localities of Euryoryzomys cerqueirai sp. nov, from Ceará and Paraíba. Green areas represent the Brejos de altitude, mountain forested areas within the Caatinga (in light ocher): A. Serra de Ibiapaba; B: Serra de Baturité; C. Brejo de Areia.Ceará:1. Sitio Corolero, Ibiapina; 2. São Benedito; 3. Guaraciaba do Norte; 4. Área do Ibama, Pacoti; 5. Sítio Friburgo, grota do Bananal, Pacoti; 6. Sítio Friburgo, grota do cafezal, Pacoti; 7. Sítio Friburgo, Sede do sítio, Pacoti; 8. Sede do Museu de História Natural do Ceará Prof. Dias da Rocha, Pacoti. 9. Sítio Sinimbu, Guaramiranga; Paraíba: 10. Areia.See Appendix I for detailed information on the collection localities.

Figure 14. Ventral (less) and lateral (right) view of the phallus of Euryoryzomys cerqueirai sp. nov., MN42930, from Ibiapaba, Ceará, Brazil.