The natural history of small mammals from Ais n Region, southern Chile

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1 Revista Chilea de Historia Natural 67: , 1994 The atural history of small mammals from Ais Regio, souther Chile La historia atural de los pequefios mamfferos de Ia Regio de Aise, sur de Chile OUGLAS A. KELT epartmet of Biology Uiversity of New Mexico Albuquerque, NM 87131, U.S.A. ABSTRACT Terrestrial small mammals from a trasitio betwee Valdivia temperate raiforest ad Patagoia steppe were collected over a two ad a half year period. Here I summarize some recet research o fourtee species from this regio, ad provide iformatio o field idetificatio, atural history, populatio structure, ad reproductio i these species. Key words: Sigmodotiae, Ecology, Patagoia, Valdivia raiforest RESUMEN Pequefios mamiferos terrestres de ua zoa de trasicio etre el bosque humedo templado de Valdivia y Ia estepa Patagoica fuero recolectados por u perfodo de dos a os y medio. Preseto u resume de los datos recietes de catorce especies de esta regio, e iformacio sobre idetificacio e el campo, historia atural, estructura de la poblacio, y reproduccio e estas especies. Palabras claves: Sigmodotiae, Ecologia, Patagoia, Bosque de lluvia Valdiviaa INTROUCTION The atural history of the Chilea mammal faua is amog the better kow i South America, largely due to the pioeerig efforts of Osgood (1943) ad subsequet work by Ma (1978). Noetheless, util recetly some areas of this coutry have remaied difficult to access, ad the fauas correspodigly poorly kow. Perhaps the fial uexplored regio of Chile is the souther extet of the Valdivia temperate raiforests ad the Fuegia forests, which lie south of these, ad the portios of Patagoia steppe which eter Chile alog the border with Argetia. Souther Chile ad adjacet parts of Argetia have recetly experieced much research (e.g. Meserve et al. 1982, 1988, 1991a, 1991b, Patterso et al. 1989, 1990, Pearso & Pearso 1982, Kelt 1989, ms, Johso et al. 1990, Kelt et al. ms, I press), ad our kowledge of these areas is improvig. The preset report is a iformal summary of the atural history ad ecology of the terrestrial small mammal faua of Chile's XI Regio. This report is based primarily o research coducted betwee 1985 ad 1987, although relevat literature is icorporated where ecessary. It is hoped that this will promote a appreciatio of the faua of this iterestig regio which curretly is edagered by rapid huma ecroachmet. Chile's XI Regio The XI regio of Chile lies betwee roughly 44o ad 49o. The Ades declie i stature towards the south, ad i this area the average pass elevatio is ca m. Because this regio lies withi the zoe of the souther tradewids, wids are predomiatly from the west, depositig heavy precipitatio o the wester flaks of the Ades, ad producig a raishadow effect to the east. Precipitatio declies from about 2500 mm atpto. Ais to roughly 240 em at Chile Chico, a east-west distace (Recibido el 7 de diciembre de 1993; aceptado el 13 de abril de 1994)

2 184 KELT of roughly 100 km. A marked vegetatio gradiet parallels the climatic tred, with Valdi vi a temperate raiforest o the wester slopes beig replaced eastward by deciduous forests domiated by souther beeches (Nothofagus spp.), park-like woods, matorrales, ad fially the steppe ad buch-grass that is characteristic of Patagoia. Because the two biotic regios here - V aldi vi a forests ad Patagoia steppehave had largely separate histories (e.g. Miiller 1973, Heusser 1990, Villagra 1990), their fauas differ substatially. A total of 16 ative species of rodet (Muridae, Sigmodotiae) plus two itroduced rodets (Muridae, Muriae) from the Old World (house mouse, Norway rat) may be foud here. Of these, oly two could be cosidered truly cosmopolita across both regios (Osgood 1943, Kelt 1989, ms). The remaiig species are foud i either Valdivia (four species) or Patagoia (eight species) habitat, or they straddle the trasitio zoe (two species). It is otable that edemism of the Valdivia mammal fau rivals that of New Zealad (Patterso 1992), log cosidered oe of the great areas of edemism. Not all species foud i this regio are cosidered i this report. The viscacia (Lagidium viscacia) ad souther cavy (Microcavia australis) occur i isolated localities, ad five bat species (Myotis chiloesis, Histiotis motaus, H. macrotus, Lasiurus borealis, ad L. ciereus) may occur here (Osgood 1943, Pearso & Pearso 1989, Redford & Eiseberg 1992). My research here did ot iclude these species however, ad little data are available o their habits or life history. Fially, the itroduced murids Mus musculus ad Rattus orvegicus occur i tows ad some other huma dwelligs. These two species are oly rarely ecoutered away from huma habitatio, however, so they are dealt with oly briefly (Table 2). Commo ames are preseted i Eglish ad Spaish, ad are take, with some mior modificatio, from Tamayo et al. (1987). Field efforts totalled almost 10,000 trapights (see Kelt (ms) for details of trappig methods), ad yielded 2,151 specimes, which have bee shared betwee the Field Museum of Natural History (Chicago, ILL) ad the Museo Nacioal de Historia Natural (Satiago, Chile). Most measuremets reported i the text ad tables (Fig. 1) are stadard ad may be readily measured. Tooth wear was measured followig Pearso (1975, 1983). Metric calipers are eeded for certai craial features, whereas a metric rule is required for exteral measuremets. The species treated here possess four teeth o either side of the upper ad lower jaw. These are a aterior icisor, which possesses a logitudial groove o its aterior face i some species, ad three molar teeth. Biogeography ad commuity structure The trasitio from the Valdivia temperate raiforest to Patagoia steppe is oe of the world's great biotic trasitios (Quitailla 1983, Veble & Lorez 1988). The marked gradiet i precipitatio was metioed above, ad this is paralleled by chages i mea temperatures as well as i both the flora ad faua. All species of small terrestrial mammal here display very heterogeous distributios across the trasitio, ad there is almost complete faual turover across a regio of about 100 km (Kelt 1989, ms). Iterestigly, however, commuities appear to retai a certai structure regardless of the locatio across this trasitio (Kelt ms). Site specific parameters such as umber of species preset, total biomass, species diversity, ad trophic structure remai remarkably cosistet across this trasitio, eve i the face of almost complete faual turover. The mammal species i this regio geerally correspod to a Patagoia faua or to a Valdivia faua (Osgood 1943, Kelt ms), but they respod idepedetly to local habitat characteristics, rather tha as two distict fauas (Kelt ms); this is also the case i may other regios (Brow ad Kurzius 1987, Morto et al. I press). Competitio has bee implicated as a profoud structurig force here (Kelt et al. ms), ad may explai why the umber of

3 SMALL MAMMALS FROM AlSEN REGION, SOUTHERN CHILE 185 IW BB ZB Fig. 1: iagram of a stadard rodet skull, showig the measuremets used i the text. Abbreviatios are: 1, orbital extesio of the lacrimal boe; 2, icisive forame; BB, breadth across the braicase; CL, legth of the coryoid process; L, legth of the maxillary diastema; F, frotal boe; GL, greatest legth of skull; OB, iterorbital breadth; IOH, iterorbital height; IW, width of the icisors; M, maxilla; MP, depth of the madible; MS, legth of the madibular diastema; ML, legth of the madible; MT, legth of the madibular toothrow; Mf, meso-pterygoid fossa; MXT, legth of maxillary 'toothrow; N, asal boe; NL, legth of the asal boes; P, parietal boe; Pf, parapterygoid fossae; Pm, premaxilla; PL, legth of palate; pp, post-palatal pits; Pt, pterygoid boes; RB, breadth across the rostrum; S, squamosal boe; ZB, breadth across the zygomatic arches. iagrama del c eo tfpico de u roedor, mostrado las medidas utilizadas e el texto. Las abreviaturas so: I, extesio orbital del hueso lagrimal; 2, forame icisivo; BB, acho de Ia caja ceflica; CL, largo del proceso corooideo; L, logitud del diastema maxilar; F, hueso frotal; GL, logitud m xima del craeo; OB, acho iterorbital; IOH, altura iterorbital; IW, acho de los icisivos; M, maxila; MP, profudidad de Ia madfbula; MOS, logitud del diastema madibular; ML, logitud de Ia madfbula; MT, logitud de Ia lfea detal madibular; Mf, fosa meso- pterigoidea; MXT, logitud de Ia lfea detal maxilar; N, hueso asal; NL, logitud del hueso asal; P, hueso parietal; Pf, fosas parapterigoideas; Pm, premaxilar; PL, logitud del paladar; pp, agujeros posteriores al paladar; Pt, huesos pterigoideos; RB, amplitud a lo largo del hocico; S, hue escamoso; ZB, acho del arco zigomatico.

4 186 KELT TABLE Exteral, craial, ad madibular measuremets for the species cosidered i this report. Acroyms are as follows (see Fig. 1 for may of these measuremets): ABLO = Abrothrix logipilis, AKOL = Akodo olivaceus, AKXA = Akodo xathorhius, AUMI = Auliscomys micropus, CHMA = Chelemys macroyx, ELMO = Eligmodotia morgai, EUCH = Eueomys chichilloides, GEV A= Geoxus valdiviaus, IRTA = lreomys tarsalis, MUO =Mus domesticus, OLLO = Oligoryzomys logicaudatus, PHXA = Phyllotis xathopygus, REPH = Reithrodo physodes. CHARACTER SPECIES ABLO AKOL AKXA AUMI CHMA ELMO EUCH Total legth N II (head+ body+ tail) Mea Std ev Tail legth N Mea Std ev Hid foot legth N Mea Std ev Ear legth N Mea Std ev Weight (gms) N Mea Std ev Greatest legth N of skull Mea Std ev Legth of asal N boe Mea Std ev Legth of the N maxillary diastema Mea Std ev Legth of the N maxillary tooth row Mea Std ev Legth of palate N Mea Std ev Breadth across N rostrum Mea Std ev Breadth across the N braicase Mea I Std ev Breadth across the N zygomatic arches Mea Std ev Width of the N II icisors (measured Mea at the alveolus) Std ev Iter-orbital N breadth Mea Std ev Iter-orbital N height Mea Std ev Legth of the N madibular diastema Mea Std ev Legth of the N II madibular toothrow Mea Std ev Greatest legth of N II the madible Mea Std ev Madibular depth N II Mea Std ev Legth of the N coryoid process Mea Std ev

5 SMALL MAMMALS FROM A SEN REGION, SOUTHERN CHILE 187 Medidas exterals, craiales, y madibulares de las especies estudiadas. Acroimos so los siguietes (vez Fig. para muchas de estas medidas): ABLO = Abrothrix logipilis, AKOL = Akodo olivaceus, AKXA = Akodo xathorhius, AUMI = Auliscomys micropus, CHMA = Chelemys macroyx, ELMO= Eligmodotia morga!, EUCH = Eueomys chichilloides, GEV A= Geoxus valdiviaus, IRT A = lreomys tarsal is, MUO = Mus domesticus, OLLO = Oligoryzomys logicaudatus, PHXA = Phyllotis xathopygus, REPH = Reithrodo physodes. CHARACTER SPECIES GEVA IRTA MUO OLLO P XA REPH Total legth N (head + body + tail) Mea Std ev Tail legth N Mea Std ev Hid foot legth N Mea Std dev Ear legth N Mea Std ev Weight (grams) N 19 II Mea Std ev Greatest legth N of skull Mea Std ev Legth of asal N boe Mea Std ev Legth of the N maxillary diastema Mea Std ev Legth of the N maxillary tooth row Mea Std ev Legth of palate N Mea Std ev Breadth across N rostrum Mea Std ev Breadth across the N 18 II braicase Mea Std ev Breadth across the N zygomatic arches Mea Std ev Width of the N icisors (measured Mea at the alveolus) Std ev Iterorbital N breadth Mea Std ev Iterorbital N height Mea Std ev Legth of the N madibular diastema Mea Std ev Legth of the N madibular toothrow Mea Std ev Greatest legth of N the madible Mea Std ev Madibular depth N Mea Std ev Legth of the N cory process Mea 1.15 I. II Std ev

6 188 KELT A brothrix logipilis Sprig (N = 57 /55) Fall (N = 95/88) partially reflect source-sik relatioships (Pulliam 1988, mass effect of Shmida ad Wilso 1985), i which trasitio habitats are uable to sustai reproductively idepedet populatios but are maitaied by costat immigratio from source areas (forest or pampa). This is ot etirely correct however, because most species which exted ito the trasitio are ideed reproducig withi the trasitio (upublished data). Whether forests are advacig or retreatig here has bee a poit of debate (e.g. Kaleta 1941, Auer 1958, 1966, Veble & Lorez 1988, Veble & Markgraf 1988), but recet evidece supports the former (Veble & Lorez 1988, Veble & Markgraf 1988). If this is correct, the we may expect the forest mammal species to follow, although such «movemets» occur over time scales which may appear imperceptible to us. Males Females Fig. 2: Sprig ad fall populatio structure of Abrothrix logipilis, by sex. Tooth wear idices are preseted such that larger values reflect older idividuals. Bars represet the proportio of the populatio of a give sex at a certai seaso which fell ito that category. Estictura poblacioal de Abrothrix /ogipilis e a prima vera y otoiio por sexo. Idices de desgaste de dietes so presetados, de maera que los valores mayores refleja idividuos de mayor edad. Las barras represeta a proporci6 de a poblaci6 de u sexo dado a lo largo de las estacioes de muestreo. species at a site is less tha expected at radom (Kelt 1989, Kelt et al. ms). The umber of species withi the raiforeststeppe trasitio clearly icreases, however (Pearso & Pearso 1982, Kelt ms), as a result of forest ad pampa species «spillig» over ito trasitioal habitats. This may SPECIES ACCOUNTS Abrothrix logipilis (Waterhouse, 1837) (Log-haired field mouse, Laucha de pelo largo) Geeral descriptio. Abrothrix logipilis is a medium-sized mouse (25-50 g), with a tail roughly 75% of the head plus body legth (Table 1 ). It is geerally a dark grayish-brow with a reddish to rufousbrow dorsum. The vetrum is paler, occasioally approachig creamy white. The ears are moderate i legth, ad ofte support a umber of reddish chiggers. Two subspecies occur i the XI Regio. The forest subspecies (A. l. apta) is darker ad heavier. Akodo logipilis suffusa occurs alog the easter frige of the Cordillera ad ito the pampa, ad is distiguished from apta by greater cotrast betwee grayish sides ad both the reddish-brow dorsum ad creamy veter, by lighter

7 SMALL MAMMALS FROM A SEN REGION, SOUTHERN CHILE 189 TABLE2 Qualitative characters useful i idetifyig species covered i this report. Caracteres cualitativos utiles e Ia idetificaci6 de las especies cubridas por este reporte.... Native species Abrothrix loqipilis post to y at < Akodo olivaceus Akodo xathorhius Auliscomvs micropus Chelemys y post to at. Smm to M 1 sl sl sl at = or sl post macroyx Eligmodotia sl sl. post to sl at or div morgai y y or post. to sl post < or sl div div Eueomys chichilloides y y post to P 1 lg << sl div sl Geoxus valdiviaus at or to p 1 y post y Ireomys tarsalis y post to sl Oliqoryzomys loqicaudatus y sl (or sl) post y < Phyllotis xathopyqus y post y < y Reithrodo physodes y st post lg << st div sl y (liear, 4) or sl < or sl < < y < < < < < < << < < < Itroduced species Mus domesticus (cheekteeth of these have 3 logitudial sl post rows of crows) < sl div << Rattus orwegicus sl post > y < NOTE: sl = slightly; div = diverget; post posterior, at aterior; st strogly.

8 190 KELT A brothrix logipilis Testes scrotal Testes abdomial Nulliparous o Parous Pregat Lactatig Fig. 3: Reproductive status for male (top) ad female (bottom) specimes of Abrothrix logipilis preseted as a fuctio of their relative age (tooth wear). Sample sizes are give as males/females. Estado reproductivo por macho (arriba) y hembra (abajo) e Abrothrix logipilis presetada como fuci6 de su edad relati.va (desgaste de dietes). Tamaiio de muestra dado como machos/hembras. colored feet, ad the more oticeably bicolored tail, with a sharper cotrast betwee the dorsum ad vetrum. The craia of Abrothix are 24 to 30 mm i legth, ad the cheekteeth are uspecialized ad small (toothrow < 5 mm). The iterorbital ad frotal regios are slightly iflated ad rouded (Table 2), ad the dorsal profile of the skull is flat, frequetly with slightly uptured asals. The zygomatic plate is arrow ad the icisive foramiae exted posteriorly to roughly [] the aterior ed of the molar toothrow. The icisors are arrow ad ugrooved, ad the maxillary toothrows ru parallel to each other. Abrothrix logipilis is larger tha the two Akodo i this regio (util recetly these were regarded as cogeers), ad the frotal ad iterorbital regios are more otably flared tha i the two Akodo. The palate termiates aterior to the posterior ed of ad the mesopterygoid ad parapterygoid fossae are of roughly equal width (Table 2). The toothrows ad diastema are slightly larger tha i Akodo olivaceus or Akodo xathorhius (Table 1 ), although this is difficult to distiguish i subadult or youg aimals. Populatio structure & reproductio. Age structure remais relatively costat over the year i this species, although populatios become somewhat more pyramidal (skewed towards youger idividuals) i the fall (Fig. 2). Abrothrix logipilis breeds i sprig, although some idividuals are active i summer (Fig. 3). Males with desceded testes have bee collected i November ( = 31 ), ecember ( = 15), ad March ( = 7); males with abdomial testes were collected i all moths of study. I November ad ecember oly the yougest males have abdomial testes; by April, all males are oreproductive (Fig. 3 top). Nulliparous females were collected i all moths of study. Parous females were also captured i all moths of study, but over half of these (13 of 23) were i the sprig moths, with the remaider i late summer ad early fall. By November, most females are reproductively active, ad i ecember they are pregat or lactatig. I late sprig all females (save oe specime) were either ulliparous juveiles, or lactatig (Fig. 3 bottom). Pregat females were collected i November ( = 12), ecember ( = 9), ad February ( = 6), ad post-partum females were ecoutered i all moths of study.

9 SMALL MAMMALS FROM A SEN REGION, SOUTHERN CHILE 191 Similar species. Chelemys ad Geoxus have shorter tails. smaller Akodo olivaceus ears ad eyes. ad loger claws. (N = 30/21) Akodo xathorhius is buffy or mfescet i color. is smaller i all measuremets. ad has msty or ochraceous fur o the feet, at the base of the tail. ad about the ares. Abrothrix logipilis is most readily cofused with A. olivaceus brachiotis. ad youg idividuals especially may be difficult to distiguish. Both A. olivaceus ad A. xathorhius have shorter ears ad hidfeet, ad are short-souted akodos. with shorter measuremets for most logitudial craial Fall (N = 96/64) measuremets (Table 2). Phallic morphology is distictive; Abrothrix logipilis has a extremely elogated phallus with a log (>50% of the shaft legth) vetral cleft. ad with a liear, vetrally curved, baculum lackig the distal portios etirely (Spotoro 1992). I both Akodo species preset i the XI Regio, the distal portio of the baculum exhibits lateral spurs ad the glas lacks the vetral cleft of logipilis. Auliscomys is larger tha A. logipilis ad has a loger tail ad larger ears, ad broader, yellow Fig. 4: Sprig ad fall populatio structure of icisors. Akodo olivaceus, by sex. Tooth wear idices ad Additioal refereces. See Pearso histogram bars are as i Fig. 3. ( 1983, 1992), Meserve et a. ( 1988, 1991 a, 199lb), Patterso et a. (1989, 1990), Kelt de dietesy, del his ograma como Fig_ 2, (ms), Kelt et al. (I press, ms). For Habitat. This species is abudat i de- relatioships of this geus ad species, see se forests above ca. 180 m elevatio Reig (1987), Gallardo et at. (1988), (Meserve et al. 1991a), but occurs a o i Spotoro et a. (1990), ad Smith & Patto most other habitats i the XI Regio (Kelt 1989, ms). It occurs occasioally i tussock grass ad very rocky areas, although here it is ucommo. Habits. Pricipally octural, the diet of this species is icompletely kow here. I orther Chile, A. logipilis is strogly isectivorous (Meserve 1981 ). I souther Chile it is strogly fugivorous (Meserve et al. 1988), but east of the Ades here it eats fugi, seeds, ad ivertebrates (Pearso 1983). (I press). Akodo olivaceus (Waterhouse, 1837) (Olivaceous field mouse, Laucba olivacea) Geeral descriptio. This is a mid-sized Akodo (20-30 g) with a tail slightly shorter (80%) tha the bead plus body legth (Table 1 ). The ears are short but cospicuous, the feet of moderate legth, ad the rostmm short. It is a rich dark brow color above ad geerally olive-grayish below. Two

10 192 KELT Akodo olivaceus Testes scrotal! o Testes abdomial Fig. 5: Reproductive status for male (top) ad female (bottom) specimes of Akodo olivaceus, preseted as a fuctio of their relative age (tooth wear). Sample sizes are give as males/females. Estado reproductivo por macho (arriba) y hembra (abajo) e Akodo olivaceus, presetado como fuci6 de su edad relativa (desgaste de dietes). Tamaiio de muestra dado como machos/hembras. subspecies occur i the XI Regio. Akodo olivaceus brachiotis is foud i forested ad may matorral areas ad has a olivebrow veter. Akodo olivaceus beatus occurs i the trasitio areas betwee forest ad pampa ad has a much lighter vetral surface ad occurs further to the east. See the accout of A. logipilis for geeral craial characters to idetify this geus. Akodo olivaceus is smaller tha A. logipilis, ad teds to be larger tha A. xathorhius (Tables 1,2). The skull of this species is very difficult to distiguish from that of xathorhius (Table 1). Pearso (1992 [i litt.]), workig ca. 500 km orth of here, foud the premaxilla-frotal legth i olivaceus to be > 16 mm, ad the maxillary toothrow > 3.4 mm, with the product of both more tha 55. I cotrast, the premaxfrotallegth i xathorhius there was < 17 mm, the toothrow < 3.5 mm, ad the product of the two is less tha 55. Populatio structure & reproductio. Populatio structure clearly reflects summer recruitmet to the autum populatio (Fig. 4). These mice reproduce from early sprig through summer (Fig. 5). Males with desceded testes have bee collected i November ( = 31), ecember ( = 1), ad March ( = 46). By April all males had abdomial testes (Fig. 5 top). Parous females have bee collected i November ( = 8) ad March ( = 8), pregat females i November ( = 4), March ( = 12), ad April ( = 1), ad post-parous females i November ( = 2), March ( = 8), ad April ( = 1). Eve youg females may become pregat (see two idividuals i November, Fig. 5 bottom). Habitat. I souther Chile ad Argetia, this species is primarily a forest dweller, but it may be foud i most habitats withi its rage, icludig meadows, matorral, woods, ad thick grassy areas (Kelt et al. I press, Pearso 1983). Habits. Primarily octural, but ofte diural as well. This species geerally requires cosiderable vegetative cover (Meserve 1981, Patterso et al. 1990), ad is strogly omivorous throughout its rage (Meserve 1981, Pearso 1983, Meserve et al. 1988). Similar species. Abrothrix logipilis is larger ad geerally darker i color, with a reddish dorsum ad lighter veter tha olivaceus. It also has a thicker, coarser tail ad is a log-souted species (Glaz 1984 ). Its ears are stouter ad ofte support

11 SMALL MAMMALS FROM A SEN REGION, SOUTHERN CHILE Akodo xathorhius Sprig (N = 45/21) Fall (N = overlap. See Geeral Characters for suggestios o distiguishig craia of these species. Youg Auliscomys may be distiguished from A. olivaceus by the presece of juveile pelage, a much stouter skull with broad, yellow icisors, ad a greater tedecy for the tail ski to slip off if the aimal is grabbed by the tail. Additioal refereces. See Pearso (1983), Mur a et al. (1987), Gozales et al. (1988), Meserve et al. (1988, 1991a, 1991b), Patterso et al. (1989, 1990), Kelt (ms), Kelt et al. (I press, ms). See Gallardo et al. ( 1988), Spotoro et al. ( 1990), ad Smith & Patto (I press) for relatioships of A. olivaceus. Akodo xathorhius (Waterhouse, 1837) (Yell ow-osed field mouse, Laucha de ariz amarilla) Geeral descriptio. Akodo xathorhius is a small Akodo 1 40 (15-20 g) with a tail ca. 65% of Males Females head plus body legth (Table 1). The pelage is grayish rufescet i j col or, with huffier, paler Fig. 6: Sprig ad fall populatio structure of Akodo xathorhius, by sex. Tooth wear idices. ad histogram bars are as i Fig. 3. Estructura poblacioal de Akodo xathorhius, por sexo. Idices de desgaste de dietes y, barras del histograma como e Fig. 2. umerous red chiggers. The craium is loger ad slimmer tha olivaceus. See the accout for A. logipilis for commets o phallic morphology. Akodo xathorhius is geerally allopatric to olivaceus (see the accout for xathorhius), although they rarely co-occur (Kelt 1989, ms); habitat is therefore ofte a useful key distiguishig these species. Akodo xathorhius is smaller ad huffier tha olivaceus, ad has yellow-orage hairs aroud the ose, the top of the feet, ad the base of the tail. Craial morphology of these differ oly statistically - idividuals frequetly uderparts. The fur about the ose, the top of the feet, ad the base of the tail is ochraceus or rusty-orage. This is the typical Akodo of Patagoia. The tail is mostly rufescet with a dorsal dark stripe which ofte termiates i a black tip. See the accout for A. olivaceus for suggestios o idetificatio of craia of this species. Populatio structure & reproductio. Fall recruitmet skews populatio structure towards youg idividuals. By sprig, age distributios are more eve, although early sprig recruitmet is evidet (Fig. 6). This species breeds primarily i sprig, but limited activity cotiues through fall (Fig. 7). Males with desceded testes have bee collected i November ( = 6) ad ecember ( = 28), ad a very few i March ( = 1) ad April ( = 3). By March, most males are sexually iactive (Fig. 7

12 194 KELT Akodo xathorhius Testes scrotal 8 o Testes abdomial Nulliparous o Parous Pregat Lactatig Fig. 7: Reproductive status for male (top) ad female (bottom) specimes of Akodo xathorhius, preseted as a fuctio of their relative age (tooth wear). Sample sizes are give as males/females. Estado reproductivo por macho (arriba) y hembra (abajo) e Akodo xathorhius, presetado como fuci6 de su edad relativa (desgaste de dietes). Tamafio de muestra dado como machos/hembras. top). Nulliparous females have bee foud i all moths of study, parous females i November ( = 2) ad ecember ( = 5) (plus oe each i March ad April), ad 12 pregat females were collected i November ( = 5) ad ecember ( = 7). Postpartum females were collected i November ( = 1), ecember ( = 3), ad i March ( = 3) ad April ( = 1 0). I November ad ecember most females are reproductively active; by March ad April the majority are 0 0 reproductively iactive, although pregat ad lactatig idividuals are foud ito early April (late Fall; Fig. 7 bottom). Habitat. This is oe of the most characteristic species of Patagoia, where it is foud i matorral ad buchgrass habitats. Whether competitive iteractios or other factors maitai this ad A. olivaceus geerally allopatric deserves further study (Kelt et al. ms). Habits. Pricipally octural, this species is omivorous, although o detailed dietary aalysis has bee coducted. Similar species. Akodo xathorhius is cofused oly with A. olivaceus, with which it is geerally allopatric; some authors cosider these species to be syoyms (Yafiez et al. 1979). Cofusio betwee the two may arise i ecotoal habitats where they may overlap (Kelt ms). Exterally these species may best be distiguished by size, color, ad 0 relative tail legth (Table 2). Craial characters differ oly statistically, ad there is much overlap; Akodo xathorhius is geerally smaller i most characters. See the accout for A. olivaceus for suggestios o craial idetificatio of this species. Collectios made alog a trasect from Coyhaique to the border east of Coyhaique Alto idicate cosiderable exteral variatio i the short-souted Akodo, ad they have bee collected sytopically ear Coyhaique Alto. Morphological itergradatio i characters suggests that hybridizatio may occur here, although geetic studies are eeded to test this cojecture. Additioal refereces. See Marcoi & Kravetz (1991), Kelt (ms), Kelt et al. (ms). For relatioships of this species see Gallardo et al. ( 1988), Afpelbaum & Reig ( 1989), Spotoro et al. (1990), Spotoro (1992).

13 SMALL MAMMALS FROM A SEN PROVINCE, SOUTHERN CHILE 195 lies parallel with the posterior ed of the palate. The mesopterygoid Aulscomys micropus fossa is arrower tha the parapterygoid fossae, ad the M 3 is Sprig (N = 34/28) smaller tha M 2 The posterior ed of the palate lies parallel to that of the toothrow, ad the posterior ed of the icisive forame is just posterior to the aterior ed of the toothrow (parallel with the middle of P 1 ; Table 2). Populatio structure & reproductio. Early Sprig recruitmet strogly skews the age structure to Q) very youg aimals, whereas by Fall these aimals mature, yieldig a Q) Fall (N = 63/56) relatively eve structured populatio with a few older idividuals (Fig. 8). This species breeds i sprig; limited activity cotiues ito early Fall (Fig. 9). Twety oe of 25 males with desceded testes were captured i November ad ecember. 0.6 I Sprig oly the yougest aimals are ot reproductively active; Males Females most were females pregat or parous. By mid-february ad March, few aimals remai reproductively active, ad i April most females are either ulliparous or are lactatig. Nie of 13 parous females, ad 14 of 18 pregat females, were j captured i November ad ecem- Fig. 8: Sprig ad fall populatio structure of ber, while all post-partum females Auliscomys micropus, by sex. Tooth wear idices ( = 13) were collected i April. ad histogram bars are as i Fig. 3. Habitat. This species prefers meadowy Estructura poblacioal de Auliscomys micropus, por sexo. h 1 h d 1 ldices de desgaste de dietes y, barras del histograma como areas Wlt US grasses a e Fig. 2. although they may also occur i ope- Auliscomys micropus (Waterhouse, 1837) (Austral greater mouse, Pericote austral) Geeral characters. This is a large ad readily idetified rodet, with mediumlegth ears, large eyes, ad a tail about 75% head plus body legth (Table 1). The pelage is thick ad soft, ad a chocolate brow or brow mixed with ochre overall with the vetrum oly slightly lighter tha the dorsum. The upper icisors are broad ad yellow, ofte with wavy or otched tips. There is a liear series of four tiy foramiae alog the posterior palate. M 3 caopied or secod growth forests of coigue (Nothofagus dombeyi) or fi.irre (N. atarctica). Habits. Maily octural, but may exhibit cosiderable diural activities at times. This species is highly herbivorous, but eats seeds, fruits, flowers, ad fugi as well (Pearso 1983, Meserve et al. 1988). Similar species. Youg Auliscomys may be cofused with A. olivaceus, but are distiguished o the basis of relative tail legth, icisor width, ad geeral craial robustess ad molar structure. This species is darker tha ay other phy lloties i souther Chile.

14 196 KELT o Auliscomys micropus o o Testes scrotal o Testes abdomial o Nulliparous o Parous Pregat Lactatig Fig. 9: Reproductive status for male (top) ad female (bottom) specimes of Auliscomys micropus, preseted as a fuctio of their relative age (tooth wear). Sample sizes are give as males/females. Estado reproductive por macho (arriba) y hembra (abajo) e Auliscomys micropus, presetado como fuci6 de su edad relativa (desgaste de dietes). Tamafio de muestra dado como machoslhembras. Additioal refereces. See Pearso (1983), Meserve et al. (1988, 1991a, 1991b), Patterso et al. (1989, 1990), Kelt (ms), Kelt et al. (I press, ms). Chelemys macroyx (Thomas, 1894) (Moutai mole-rat, Rata topo cordilleraa) Geeral descriptio. This is a robust species (60-65 g); the ears ad tail are relatively short (Table 1), the ails o the 1:. forefeet log, ad the ski is loose, adaptig Chelemys well to a semifossorial existece. The fur is short but thick, ad a dark olive brow dorsally, fadig to a huffy brow o the sides ad light huffy brow or early white veter. The M 3 lies posterior to or equal with the posterior ed of the palate, ad the ic s ve foramia termiates slightly posterior to the aterior ed of P 1 Cheekteeth coverge posteriorly, but ot strogly. The mesopterygoid ad parapterygoid fossae are roughly of equally width. The M 3 is smaller tha M 2 There are o post-palatal pits (Table 2). Populatio structure & reproductio. Limited data suggests that sprig recruits do ot veture out of their burrows util late sprig, yieldig a seemigly adult-skewed populatio. By Fall, these youg idividuals are more active ad domiate the trappable populatio (Fig. 10). Males become reproductively active by November, ad a few are active util late February ad early March (Fig. 11 top). Most females become parous by November; may are pregat or lactatig by this time (Fig. 11 bottom; see Pearso 1983). I February some females are pregat or parous, but by March ad early April most are ulliparous. Pregat females were collected i November ( = 6) ad March ( = 1 ), ad post-partum females were caught i November ( = 4) ad ecember ( = 4). Habitat. I the XI Regio Chelemys is foud i areas of lush grasses ad loose soils, ofte with a scattered caopy of lega (Nothofagus pumilio) or irre (N. atarctica). It may also be foud i dryer Valdivia forest ad rarely i matorral habitat. Habits. This aimal is primarily subterraea, although it may make occasioal forays o the surface. Noctural ad diural, its diet is icompletely kow. Eats various plat parts as well as fugi ad ivertebrates (Pearso 1983).

15 SMALL MAMMALS FROM AlSEN REGION, SOUTHERN CHILE Chelemys macroyx Sprig (N = 19/18) coloratio, loger ad wider icisors, ad geeral craial robustess. Additioal refereces. Pearso (1983, 1984), Kelt (ms), Kelt et al. (ms. Cteomys coyhaiquesis (Kelt & Gallardo, 1994) (Tuco-tuco de Coyhaique) Males Fall (N = 10/9) Females Fig. I 0: Sprig ad fall populatio structure of Chelemys macroyx, by sex. Tooth wear idices ad histogram bars are as i Fig. 3. Estructura poblacioal de Chelemys macroyx, por sexo. Idices de desgaste de dietes y, barras del histograma como e Fig. 2. Similar species. Geoxus is smaller ad more delicate. Youg Chelemys ca be distiguished from Geoxus by the juveile pelage ad more robust skull, ad the broader icisors. Auliscomys occurs sytopically with Chelemys but has loger, fier fur, shorter claws, loger ears, larger eyes, ad a loger tail. Youg of this species are occasioally cofused with youg of Abrothrix logipilis. Chelemys may be distiguished from A. logipilis by the shorter tail, the log claws o the forefeet, the more uiform pelage Geeral descriptio. This is a relatively small species of Cteomys. Coloratio is typical of may tucotucos, with log dusky-brow fur over the body ad a dark mid-dorsal streak. The ears ad tail are very short, the eyes reduced, ad the ails log. The icisors are large, procumbet, broad, ad yellow, ad the molar teeth are uiquely L- shaped. The skull is broad ad very robust, ad ot readily cofused with ay other species of the regio. Populatio structure & reproductio. These aimals breed i early sprig. Two males with desceded testes, ad two pregat females, were collected i November. Nulliparous females were collected i November, ecember, March, ad April, ad three parous _j females were collected i November. Habitat. To date this species is kow oly ear Coyhaique Alto ad Chile Chico, i dry, loose soiled habitat with tussock grass ad matorral (Kelt & Gallardo 1994). Habits. This species is wholly subterraea ad active both diurally ad octurally. Its diet has ot bee studied i detail, but is primarily vegetatio. Similar spe ies. Cteomys are distiguished from all other rodets here o the basis of size ad robustess, ad their wholly subterraea habit. Additioally, the large procumbet icisors ad L-shaped molar teeth are distictive. Cteomys magellaicus osgoodi is larger tha coyhaiquesis, may occur i the XI Regio, but is edagered i Chile (Glade 1988) ad likely extict i this regio.

16 198 KELT Chelemys macroyx o Testes.scrotal o Testes abdomial Nulliparous o Parous Pregat Lactatig are pure white to the roots of the hairs, ad the vetrum is covered with pure white hairs which have gray roots. The soles of the hidfeet are at least partly furred. The mesopterygoid fossa is arrower tha the parapterygoid fossa, ad the M 3 is smaller tha The aterior ed of M 1 bears a otch, there are post-palatal pits, ad the palate termiates posterior to the too throw. The posterior ed of the icisive forame is equal to or slightly posterior to P 1 (Table 2). Populatio structure & reproductio. ata o populatio structure are limited (Fig. 12). The yougest aimals captured were evidetly subadults based o tooth wear (Fig. 13). The breedig seaso appears prologed i this species (Fig. 13). Males with desceded testes (Fig. 13 top) were captured i ecember ( == 2) ad i April ( == 4). parous female was caught i March, ad oe pregat female i ecember (Fig. 13 bottom). Three post-partum females were captured i ecember ad April. Habitat. Eligmodotia may be foud i tussock grass habitat, ad less frequetly i ope shrublad with buchgrasses. Fig. 11: Reproductive status for male (top) ad female (bottom) specimes of Chelemys macroyx preseted as a fuctio of their relative age (tooth wear). Sample sizes are give as males/females. Estado reproductivo por macho (arriba) y hembra (abajo) e Chelemys macroyx, presetado como fuci6 de su edad relativa (desgaste de dietes). Tamaiio de muestra dado como machos/hembras. Additioal refereces. See Kelt & Gallardo (1994 ). Eligmodotia morgai (Alle, 1901) (Patagoia silky-footed mouse, Ratita patagoica de piel sedosa) Geeral descriptio. Eligmodotiais a small mouse with a tail equal to or slightly shorter tha the head-body legth (Table 1). It has light colored, silky fur; the chi ad throat Habits. This mouse is octural ad eats seeds ad isects. Similar species. Phyllotis is larger ad heavier, ad has larger ears ad aked soles. Akodo xathorhius has a shorter, less haired tail, ad has otable rufescet or orage coloratio (see accout of that species). Additioal refereces. See Pearso et al. (1987), Kelt (ms), Kelt et al. (ms). For recet taxoomic status, see Ortells et al. (1989) ad Kelt et al. (1991). Eueomys chichilloides (Waterhouse, 1839) (Chichilloid silky mouse, Rat sedosa chichilloide) Geeral descriptio. Eueomys chichilloides is a large bodied phyllotie (55 g)

17 SMALL MAMMALS FROM A SEN REGION, SOUTHERN CHILE 199 The lacrimal boes exted over the Eligmodotia morgai Sprig (N = 3/2) aterior portio of the orbit (Table 2). Reproductio. Eueomys were collected oly i ecember. Two males had desceded testes. Oe female was ulliparous, whereas three females were pregat. 1.0 Habitat. Barre, rocky, ofte widswept slopes. This species is ecoutered at seemigly bleak sites with little vegetatio. Habits. Eueomys chichilloides here is strictly octural, ad eats seeds ad isects. Similar species. Eueomys is most readily cofused with Reithrodo, both of whom have grooved icisors. Fall (N = 26/15) These may readily be distiguished by the followig characteristics. Reithrodo has loger hidfeet (32 Males Females mm vs 26 mm), with reduced 1st ad 5th toes ad furry soles, ad a loger tail (80-85 mm vs mm). The palate of Reithrodo exteds posterior to the molar toothrow, whereas i Eueomys it termiates roughly parallel or slightly posterior to M 3 Additioally, the pterygoid boes diverge strogly from parallel i Reithrodo, but less strogly i Eueomys. The suture betwee the frotal ad parietal boes is differet i these two taxa; i Reithrodo the Fig. 12: Sprig ad fall populatio structure of Eligmodotia morgai by sex. Tooth wear idices ad histogram bars are as i Fig. 3. suture rus perpedicular to the medial suture, whereas i Eueomys the frotal-parietal suture rus latera-posterior Estructura poblacioal de Eligmodotia morgai, por sexo. from the medial suture. Fially, Idices de desgaste de dietes y, barras del histograma como Reithrodo is geerally allotopic to e Fig. 2. Eueomys, occurrig i moist seeps ad areas with abudat short grasses. lreomys has grooved icisors, but these are thier tha i Eueomys. Additioally it has a much loger tail, shorter feet, ad the molars are distictively prismatic ad with a large head, short ears ad tail, ad relatively short feet. The tail is roughly half the legth of the head plus body (Table 1). Its fur is soft ad richly colored tawy ad ochraceous huffy with black lies. The soles of the hidfeet are aked. The upper icisors bear lateral grooves. The skull is robust, ad possesses a distictive postpalatal depressio i the mesopterygoid fossa. The ostrils i this species (as i Reithrodo) are otably flared laterally. The root ofl 1 forms a substatial projectio alog the lateral surface of the madible. deeply dissected. Other large-bodied rodets i this regio lack grooved icisors ad are darker i color. Additioal refereces. See Pearso (1987), Pearso & Christie (1991), Kelt (ms), ad Kelt et al. (ms). For recet taxoomic status, see Reise & Gallardo (1990).

18 200 KELT ad varies from ciamo brow to early black i color. Geoxus valdiviaus bicolor occurs east of Eligmodotia morgai the forests, ad is lighter i color, geerally with a olive-gray to grayish-white veter. The skull is Testes scrotal o Testes abdomial sleder ad delicate, the rostrum log, ad the molars small. The maxillae are iflated ad there is a.. short shelf behid M 2 The aterior ed of the mesopterygoid fossa is U-shaped ad lies posterior to the molar too throw. The premaxillary exteds to or slightly aterior of the asals. There is a large forame i the parapterygoid fossa. The last upper molar is much smaller tha the secod. The mesopterygoid ad Nulliparous o Parous parapterygoid fossae have roughly Pregat Lactatig the same diameter. There are o post-palatal pits. The posterior ed.. of the palate lies roughly equal to the posterior ed of M ad the icisive foramia termiates aterior to the aterior ed of the toothrow (Table 2). Reproductio. Specimes have bee collected i the XI Regio oly i March ad November. Males with desceded testes have bee captured i both moths. A sigle parous female was captured i j March, ad ulliparous females Fig. 13: Reproductive status for male (top) ad female have bee captured i March ad (bottom) specimes of Eligmodotia morgai, November. preseted as a fuctio of their relative age (tooth Habitat. The omial subspecies is a wear). Sample sizes are give as males/females. forest dweller, although it occassioally Estado reproductivo por macho (arriba) y hembra (abajo) e spills out ito woods habitat or lush Eligmodotia morgai, presetado como fuci6 de su edad relativa (desgaste de dietes). Tamaiio de muestra dado meadows borderig forests. Geoxus como machos/hembras. valdiviaus bicolor occurs further east, where it is ucommo ad has bee captured Geoxus valdiviaus (Philippi, 1858) i thick matorral ear Coyhaique Alto. (Valdivia mole-mouse, Rat topo Habits. Geoxus valdiviaus valdiviaus valdiviao) is primarily octural, ad eats small ivertebrates, vegetatio, ad fugi (Pearso 1983, Meserve eta!. 1988). It is partly subterraea, but ofte is foud i dese litter or herbaceous vegetatio, or i Geeral descriptio. Geoxus is a small mouse (25 g, 100 mm head plus body legth; Table 1). The eyes ad ears are very small ad the claws o the forefeet are log. The pelage is short ad thick. Two subspecies occur i the XI Regio. I the forest subspecies (G. v. valdiviaus) the dorsal ad vetral pelage is ot strogly cotrasted, ruways alogside logs. Very little is kow about the habits of G. v. bicolor. Similar species. Akodo all have loger tails, shorter claws, ad larger eyes ad ears, eve whe youg. Chelemys is larger

19 SMALL MAMMALS FROM A SEN REGION, SOUTHERN CHILE 201 Oligoryzomys logicaudatus Ireomys tarsalis (Philippi, 1900) (Chilea arboreal-rat, Rata arb6rea) Males Sprig (N = 4/3) Fall (N = 52/48) Fig. 14: Sprig ad fall populatio structure of Oligoryzomys logicaudatus, by sex. Tooth wear idices ad histogram bars are as i Fig. 3. Estructura poblacioal de 0/igoryzomys logicaudatus, por sexo. Idices de desgaste de dietes y, barras del histograma como e Fig. 2. Females ad more robust. Geoxus may be distiguished from youg Chelemys by the adult pelage ad less robust body. Additioally, the.detitio of Chelemys is much more robust, with the molar teeth of eve youg idividuals larger tha i adult Geoxus. Additioal refereces. See Pearso (1983, 1984), Meserve et al. (1988, 1991a, 1991b), Patterso et al. (1989, 1990), Kelt (ms), ad Kelt et al. (I press, ms). Geeral descriptio. Ireomys tarsalis is readily recogized as a large mouse with a tail much loger (about tha the head plus body (Table 1). The eyes are very large ad the pelage is thick ad soft. The dorsum is grayish ciamo rufous, ad the vetrum is huffy ciamo with plumbeous uder color. The molar teeth are distictive, beig deeply dissected ad prismatic, with deep reetrat agles opposite each other (ot alterate) ad perpedicular to the toothrow, ad early meetig. The asals exted beyod the premaxillary boes by ca mm. I mature specimes there is ofte a marked ridge o the lateral side of the madible, delieatig the masseteric fossa. The mesopterygoid ad parapterygoid fossae are equal i diameter. There is geerally a sigle post-palatal pit. The icisive foramia termiates posterior to the aterior ed of the molar tooth row, ad the posterior ed of the palate lies eve with the posterior ed of the toothrow (Table 2). Reproductio. I have captured this species i the XI Regio oly i March. Two males had scrotal testes, two females were ulliparous, ad a third female had six embryos. Habitat. This is strictly a forest species, ad may be largely arboreal. They are frequetly captured i traps placed alog logs or at the bases of trees, or i subterraea cavers formed by superficial roots ad boulders covered with liches ad mosses.. Habits. Noctural, this species climbs very readily. It is herbaceous, eatig large amouts of vegetatio, seeds, ad fruits (Pearso 1983, Meserve et al. 1988). Similar species. Oligoryzomys logicaudatus lacks grooves o the icisors ad is geerally smaller ad thier tha Ireomys, ad it is more readily agitated. Phyllotis occurs i dryer, o-forested habitats, ad lacks grooves o the icisors.

20 202 KELT Oligoryzomys logicaudatus Testes scrotal o Testes abdomial o Nulliparous Pregat Lactatig Fig. 15: Reproductive status for male (top) ad female (bottom) specimes of Oligoryzomys logicaudatus, preseted as a fuctio of their relative age (tooth wear). Sample sizes are give as males/females. Estado reproductivo por macho (arriba) y hembra (abajo) e Oligoryzomys logicaudatus, presetado como fuci6 de su edad relativa (desgaste de dietes). Tamafio de muestra dado como machos/hembras. Its head-body legth is greater tha lreomys, it is heavier, has loger ears ad a shorter tail. Additioal refereces. See Pearso (1983), Meserve et al. (1988, 1991a, 199lb), Patterso et al. (1989, 1990), Kelt (1993, ms), ad Kelt et al. (I press, ms). Oligoryzomys logicaudatus (Beett, 1832) (Log-tailed rice rat, Rat de los espios) Geeral characters. This is a small mouse with log hidfeet ad a early hairless tail much loger tha the body ( 130 percet of head plus body; Table 1). The pelage is short ad dark buff. A oticeable character is the ervous excitability of this species; it is readily agitated whe hadled, ad geerally appears tese or high-strug. The skull is rouded ad bears a large, rouded ifraorbital caal ad a large post-palatal caal. The mesopterygoid fossa is arrower tha the parapterygoid fossae, ad M 3 is smaller tha M 2 Post-palatal pits are preset, the palate termiates posterior to the too throw, ad the icisive forame termiates posterior to the toothrow (Table 2). Populatio structure & reproductio. Limited data here suggests that witer survival is low (Fig. 14). Fall populatios are large, with few very youg or very old idividuals. By sprig, populatios appear much reduced. This ability for populatios to icrease rapidly uder favorable evirometal coditios has bee demostrated i populatios i Valdivia forests (Murua et al. 1986). This species breeds from early sprig through late summer (Fig. 15). Most idividuals captured i sprig were sexually active. Sevetee of 25 males captured i March had desceded testes, ad 20 of 25 females were pregat. Post-partum females were captured i November, March ad April. As late as March, most idividuals were active. I April, however, the majority of idividuals were sexually iactive. Habitat. Oligoryzomys is foud i ay habitat with available water earby. Populatios are eruptive, ad respod rapidly to local food availability; coversely, they may be very rare locally whe coditios are poor.

21 SMALL MAMMALS FROM A SEN REGION, SOUTHERN CHILE Phyllotis xathopygus Sprig (N = 6/6) etal. (1988, 1991a, 1991b), Patterso et al. (1989, Kelt (ms), ad Kelt et al. (I press, ms). See Carleto & Musser (1989) ad Gallardo ad Palma ( 1990) for relatioships with other oryzomyie rodets. Q) Phyllotis xathopygus (Waterhouse, 1837) (Austral leaf-eared mouse, Lauch6 orejudo austral) 0.2 Geeral characters. The leaf-eared mouse is a large phyllotie, with Q) _ Fall (N = 84/97) large ears ad a well-haired tail equal 1.6 to its head-body legth (Table 1). It 1.4 is a dark buff color mixed with brow, ad the vetrum is heavily washed with ochraceous buff. The 1.0 mesopterygoid fossa is arrower tha the parapterygoid fossae. M 3 is 0.8 smaller tha The palate termiates 0.6 posterior to the aterior ed of the tooth row, ad the posterior ed 0.4 of the icisive forame lies posterior to the aterior ed of the 0.2 toothrow (Table 2). _ Populatio structure & repro- Males Females ductio. ata o sprig populatio structure are limited, but appears adult domiated (Fig. 16). By Fig. 16: Sprig ad fall populatio structure of Phyllotis xathopygus, by sex. Tooth wear idices ad histogram bars are as i Fig. 3. Estructura poblacioal de Phyllotis xathopygus, por sexo. Idices de desgaste de dietes y, barras del histograma como e Fig. 2. Habits. This species is octural ad graivorous, although it also eats berries. fruits, ad some isects (Meserve 1981, Pearso 1983, Meserve et al. 1988). Similar species. Ireomys is geerally much larger tha 0/igoryzomys, ad is readily distiguished by the grooved icisors, deeply dissected molar teeth, the larger ears ad eyes, ad the thicker tail. Phyllotis has much larger ears ad is a much heavier aimal with a shorter tail. Additioal refereces. See Pearso (1983), Mu1a et al. (1986, 1987), Meserve March, most captures are of youg, sexually iactive idividuals. These are sprig breeders (Fig. 17). Five of seve males with desceded testes were captured i November ( = 3) ad ecember ( = 2). By February ad March most males are sexually iactive (Fig. 17 top). Six parous females were collected i November ( = 2), February ( = 1), ad March ( = 3), ad te pregat females were captured i November ( = 2), ecember ( = 6), ad February ( = 2). Post-partum females were collected i November ad February ( = 1 each moth), March ( = 7), ad April ( = 8). By March ad April, most females are youg ad ulliparous, ad the larger idividuals are lactatig (Fig. 17 bottom). Habitat. Phyllotis occurs i rocky slopes ad cliffs i drier areas.

22 204 KELT 1.4 Phyllotis xathopygus Testes scrotal o Testes abdomial Eligmodotia is smaller ad has a relatively loger tail. Additioal refereces. See Kelt (ms), Kelt et al. (ms). For recet taxoomy, see Walker et al. (1984 ). Reithrodo physodes (Olfers, 1818) (Rabbit rat, Rata coejo) Geeral characters. This mouse has the geeral appearace of a small rabbit. It is a large rodet (65 g) B with a short tail (65% of head plus body legth) ad medium-legth, rouded ears (Table 1). The vetrum is strogly washed with 1.4 ochraceous hairs with gray roots. Nulliparous The hidfeet are very log, with o Parous Pregat reduced first ad fifth digits, ad Lactatig well furred soles. The fur is silky ad loose. The upper icisors are grooved. There is a otable aterior projectio from the pre-orbital portio of the zygomatic plate, formig a large, oval ifraorbital caal. The styloid process bears a thi projectio lateral to the occipital codyles. The mesopterygoid fossa is arrower tha i Eueomys, ad the parapterygoid fossae bear a large aterior depressio. The pos- ' j terior ed of the palate bears a Fig. 17: Reproductive status for male (top) ad female (bottom) specimes of Phyllotis xathopygus, preseted as a fuctio of their relative age (tooth wear). Sample sizes are give as males/females. Estado reproductivo por macho (arriba) y hembra (abajo) e Phyllotis xathopygus, presetado como fuci6 de su edad relativa (desgaste de dietes). Tamaiio de muestra dado como machos/hembras. Habits. This species is octural. Its diet has ot bee quatified, but they are largely herbivorous, also eatig seeds ad isects. Similar species. Reithrodo, Eueomys, ad lreomys all have grooved upper icisors; the former two species have short tails, while lreomys has a much loger tail tha Phyllotis. Auliscomys has a relatively loger tail (75% head plus body legth) ad uiform chocolate brow coloratio. depressio ad several tiy foramiae. The reetrat agles i the maxillary cheekteeth ru posteriorly, while those o the madibular cheekteeth are ateriorly directed. The icisive foramia is log (to the middle of P 1 ). Lateral to the icisive foramiae the maxillary ad premaxillary boes are ridge-shaped. There is a large fossa (> 2 mm diameter) i the frotal boes of the optic wall. The lacrimal boes are large, extedig ito the atero-dorsal portio of the orbit (Table 2). Populatio structure & reproductio. ata are limited for this species, but suggest recruitmet through sprig ad summer (Fig. 18). Witer survivors domiate the sprig age structure; these mature by fall, yieldig a more eve age distributio, ad producig youg which will overwiter. These mice breed i sprig (Fig. 19). Ma-

23 SMALL MAMMALS FROM AlSEN REGION, SOUTHERN CHILE 205 Reithrodo physodes Sprig (N 9/12) Reithrodo physodes Testes scrotal o Testes abdomial! Fall (N o Nulliparousl o Parous Pregat Lactatig Males Females Fig. 18: ad fall populatio structure of Reithrodo physodes, by sex. Tooth wear idices ad histogram bars are as i Fig. 3. Estructura poblacioal de Reithrodo, por sexo. Idices de desgaste de dietes y, barras del histograma como e Fig. 2. les i ecember had desceded testes. Two parous females were collected i November ad ecember, ad six pregat females were collected November ( = 3), ecember ( = 2), ad March ( = 1). A sigle post-partum female was captured i April. Habitat. Reithrodo lives i subterraea burrows, geerally where sufficiet moisture provides a cotiuous carpet of grasses. They may occur i matorrales if grasses are earby. Habits. These octural herbivores eat maily grass, ad may cosume their body weight i grass i a sigle ight (Pearso 1988). species. Reithrodo has very log hidfeet ad is uique here i havig Fig. 19: Reproductive status for male (top) ad female (bottom) specimes of Reithrodo physodes, preseted as a fuctio of their relative age (tooth wear). Sample sizes are give as males/females. Estado reproductive por macho (arriba) y hembra (abajo) e Reithrodo physodes, presetado como fuci6 de su edad relativa (desgaste de dietes). Tamaiio de muestra dado como machos/hembras. reduced first ad fifth digits o the hidfeet. Additioally, Eueomys has a shorter tail,smaller ears, ad shorter hidfeet. Ireomys is foud oly i forested areas, ad has much loger tail. All other large rodets here lack grooved icisors. Phyllotis has larger ears ad a loger tail. Auliscomys is dark i color ad has broader, yellow icisors. Chelemys has a shorter tail ad shorter ears, ad log claws. Additioal refereces. See Pearso (1988), Kelt (ms), Kelt et al. (ms).

24 206 KELT ACKNOWLEGMENTS This research was partially supported by the Orgaizatio of America States ad was carried out durig the research phase of the author's Master's research. Facilities i Chile were kidly provided by the Istituto Profesioal de Osoro (Osoro, Chile), ad by the Corporaci6 Nacioal Forestal i Coyhaique. Sr. Hugo Toledo Neira, Guardaparque at Parque Nacioal Coyhaique, ad his family, deserve special ackowledgemet for makig my visits to this regio thoroughly ejoyable. My uderstadig of «Castellao» ad of Chile beefitted by the tireless patiece of Sr. Ricardo Martiez ad Sr. Jua Pablo Yutrofc. r. Oliver Pearso helped me to see rodet habitat i what was the a foreig world, ad provided useful commets o this mauscript. My field work ad this mauscript also beefitted greatly from the series of keys that r. Pearso has prepared to the species occurrig i a earby regio of Argetia (e.g. Pearso 1992 [i litt.]). LITERATURE CITE APPELBAUM LI & OA REIG (1989) Allozyme geetic distaces ad evolutioary relatioships i species of akodotie rodets (Cricetidae: Sigmodotiae). Biological Joural of the Liea Society 38: BROWN JH & M KURZIUS (1987) Compositio of desert rodet fauas: combiatios of coexistig species. Aales Zoologici Feici 24: CARLETON M, & GG MUSSER (1989) Systematic studies of oryzomyie rodets (Muridae, Sigmodotiae): A syopsis of Microryzomys. Bulleti of the America Museum of Natural History 191:1-83. GALLARO MH, G AGUILAR & 0 GOICHOECHEA (1988) Sistematics of sympatric cricetid Akodo (Abrothrix) rodets ad their taxoomic implicatios. Medio Ambiete 9: GALLARO MH & E PALMA (1990) Systematics of Oryzomys logicaudatus (Rodetia: Muridae) i Chile. Joural of Mammalogy 71: GALLARO MH & B PATTERSON (1985) Chromosomal differeces betwee two omial subspecies of Oryzomys logicaudatus Beet. Mammalia Chromosomes Newsletter 25: GLAE AA, ed (1988) Red list of Chilea terrestrial vertebrates. Chilea Forest Service (CONAF). Satiago, Chile. GLANZ WE (1984) Ecological relatioships of two species of Akodo i cetral Chile. Joural of Mammalogy 65: GONZALES LA, R MURUA, P MESERVE, & YC JOFRE (1988) Cosecuecias demograficas de Ia maipulaci6 experimetal e Ia composici6 de edades de Akodo olivaceus (Rodetia, Cricetidae). Boletf de Ia Sociedad de Biologfa de Cocepci6, Chile 59: HEUSSER CJ (1990) Late-glacial ad Holocee vegetatio ad climate of subatarctic South America. Review of Palaeobotay ad Palyology 65:9-15. JOHNSON WE, WL FRANKLIN & JA IRIARTE (1990) The mammalia faua of the orther Chilea Patagoia: a biogeographical dilemma. Mammalia 54: KELT A ( 1989) Biogeography ad assemblage structure of small mammals across a trasitio zoe i souther Chile. Upubl. MS thesis, Norther Illiois Uiversity, ekalb, IL. KELT A (1993) Ireomys tarsalis. Mammalia Species 447:1-3. KELT A (ms) Ecology of small mammals across a strog evirometal gradiet i souther South America. Submitted to Joural of Mammalogy. KELT A & MH GALLARO (1994) A ew species of tuco-tuco, geus Cteomys (Rodetia: Cteomyidae) from Patagoia Chile. Joural of Mammalogy 75: KELT A & R MARTINEZ (1989) Notes o the distributio ad ecology of two marsupials edemic to the Valdivia forests of souther South America. Joural of Mammalogy 70: KELT A, PL MESERVE & BK LANG (I press). Quatitative habitat associatios of small mammals i a temperate raiforest i souther Chile: empirical patters ad the importace of ecological scale. Joural of Mammalogy. KELT A, RE PALMA, MH GALLARO & JA COOK (1991 ). Chromosomal multiformity i Eligmodotia (Muridae, Sigmodotiae), ad verificatio of the status of E. morgai. Zeitschrift fiir Siiugetierkude 56: KELT A, ML TAPER & PL MESERVE (ms) Assessig the impact of competitio o the assembly of commuities. Submitted to Ecology. MANN GF (1978) Los pequei'ios mamfferos de Chile: marsupiales, quir6pteros, edetados y roedores. Gayaa (Cocepci6, Chile) 40: MARCONI PN & FO KRAVETZ ( 1991) Akodo xathorhius moultig i a thermally stressed eviromet (Rodetia, Criceticae). Mammalia 55: MESERVE PL, R MURUA. ON LOPETEGUI & JR RAU ( 1982) Observatios o the small mammal faua of a primary temperate rai forest i souther Chile. Joural of Mammalogy 63: MESERVE PL, A KELT & R MARTINEZ (199la) Geographical ecology of small mammals i cotietal Chile Chico, South America. Joural of Biogeography 18: MESERVE PL, BK LANG, R MURUA, A MUNOZ & LA GONZALEZ ( 1991 ). Characteristics of a terrestrial small mammal assemblage i a temperate raiforest i Chile. Revista Chilea de Historia Natura164: MESERVE PL, B PATTERSON & BK LANG (1988) Trophic relatioships of small mammals i a Chilea temperate raiforest. Joural of Mammalogy 69:

25 SMALL MAMMALS FROM AISEN REGION, SOUTHERN CHILE 207 MORTON SR, JH BROWN, A KELT & JRW REI (I press) Comparisos of commuity structure amog small mammals of North America ad Australia deserts. Australia Joural of Zoology. MURUA R, LA GONZALES & PL MESERVE (1986) Populatio ecology of Oryzomys logicaudatus philippii (Rodetia: Cricetidae) i souther Chile. Joural of Aimal Ecology 55: MURUA R, PL MESERVE, LA GONZALES & C JOFRE (1987) The small mammal commuity of a Chilea temperate rai forest: lack of evidece of competitio betwee domiat species. Joural of Mammalogy 68: MLLER P (1973) The dispersal cetres of terrestrial vertebrates i the Neotropical realm. A study i the evolutio of the Neotropical biota ad its ative ladscapes. W. Juk B. V., The Hague. OR TELLS MO, OA REIG, RL W AINBERG, GE HURTA- O E CATALFO & TML GENTILE E FRONZA.( 1989) Cytogeetics ad karyosystematics of phyllotie rodets (Cricetidae: Sigmodotiae). II. Chromosome multiformity ad autosomal polymorphism i Eligmodotia. 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SMITH MF & JL PATTON (I press) iversificatio of South America murid rodets: evidece from mitochodrial NA sequece data for the Akodotie tribe. Biological Joural of the Liaea Society. SPOTORNO AE, CA ZULETA & A CORTES (1990) Evolutioary systematics ad heterochroy i Abrothrix species (Rodetia, Cricetidae). Evoluci6 Biol6gica 4: SPOTORNO AE ( 1992) Parallel evolutio ad otogey of simple peis amog New World cricetid rodets. Joural of Mammalogy 73: TAMAYO M, H NUNEZ & J YANEZ ( 1987) Lista sistematica actualizada de los mamfferos vivietes e Chile y sus ombres comues. Noticierio Mesual, Museo Nacioal de Historia Natural 312:1-13. VEBLEN TT & C LORENZ (1988) Recet vegetatio chages alog the forest/steppe ecotoe of orther Patagoia. Aals of the Associatio of America Geographers 78:93-11 t. VEBLEN TT & V MARKGRAF (1988) Steppe expasio i Patagoia? 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