2 
series employed by Frost et al. (1991: 3-15) and added to the 
character matrix shown in Frost et al. (1991: appendix 2) see Table 
2. Branch and bound analyses were performed using Paup 4.0ba 
(Swofford, 1999) set at maximum parsimony, with a maximum trees 
setting of 1000 and all characters treated as unordered and of equal 
weight. Bootstrap analyses (Felsenstein, 1985) were made to pro- 
vide an assessments of confidence limits of nodes, with 1000 
replicates of 100 random addition sequence replicates. Bremer 
support indices were calculated by increasing the upper bound of the 
shortest tree by one step, repeating the branch and bound analysis 
and producing a strict consensus tree; the process was repeated, 
progressively increasing the length of the suboptimal cladograms by 
a single step until all clades of interest no longer occurred on the 
consensus tree; the level at which each node collapsed was recorded 
(Kitching et al., 1998). Both accelerated (ACCTRAN) and delayed 
(DELTRAN) optimizations were used to map character evolution. 
The trees obtained were compared with those in Frost et al. (1991) 
and the results of the analysis are given below. 
RESULTS 
Hylomys megalotis, sp. nov. 
HOLOTYPE. BMNH 1999.44 (field number 5/99) male, body in 
alcohol, skull extracted. Collected 15 January 1999 by M. F. 
Robinson. 
TYPE LOCALITY. Environs of Ban Muang and Ban Doy, c 18 km 
North of Thakhek, Thakhek district, Khammouan Limestone National 
Biodiversity Conservation Area, Khammouan Province, Lao Peoples 
Democratic Republic, 17°33'15"N 104°49'30"E. Habitat: steep slopes 
around the base of massive limestone karst, covered in rock and large 
boulders, with an underlying soil base and heavily degraded mixed 
deciduous forest, scrub and bamboo. Low lying areas away from the 
karst had been cleared for cultivation of paddy rice. 
PARATYPES. BMNH 1999.45 (field number 14/99) collected 16 
January 1999; 1999.46 (field number 15/99) and 1999.48 (field 
number 17/99) collected 17 January 99, females, bodies in alcohol, 
skulls extracted; 1999.47 (field number 16/99) collected 17 January 
1999, male, skin and internal organs in alcohol, skull and skeleton. 
All specimens were collected by M.F. Robinson from the same 
locality as the holotype. 
DIAGNOSIS 
Ears large, rhinarium elongated; first and fifth digits of forefeet long, 
claws long, cheiridia large and rounded; cheiridia on hindfeet large, 
soles naked; pre-anal gland with single opening. Skull with posterior 
region of nasals extending to level of antorbital rim; maxilla and 
parietal widely separated by frontal in supraorbital region; long 
grooves for palatine artery present in palate; anterior palatine fo- 
ramina anterior to maxillary palatine suture; antorbital fossa shallow; 
nasolabialis fossa shallow; posteroventral maxillary process of 
zygoma distinct; antero-ventral process of alisphenoid present. Den- 
tition robust. Third upper premolar (P3) large with well developed 
lingual cusp and three roots. Neural spine of axis low. 
DESCRIPTION 
Medium sized Hylomys with a long tail, approximately 75% of head 
and body length. Pelage grey, long, soft and very fine, lacking 
flattened spinous hairs; individual hairs grey for most of their length, 
then buff with buff or black tips. Dorsal region of rhinarium narrow, 
elongate posteriorly; ears prominent, very large, rounded. First and 
P.D. JENKINS AND M.F. ROBINSON 
fifth digits of forefeet lengthened, claws long and moderately stout; 
sole and tarsal region of hindfeet naked, cheiridia large. Pre-anal 
gland with single opening immediately posterior to cloaca. Two 
pairs of inguinal mammae present. 
Skull elongate, moderately slender and somewhat flattened in 
appearance (see Figs. 1—2); dorsal profile more or less straight, 
showing a gradual increase in height from anterior of rostrum to 
braincase. Rostrum long, slender and moderately shallow, nasals 
long extending posteriorly to, or slightly beyond, level of antorbital 
rim; posterodorsal region of premaxilla widely separated from 
anterodorsal region of frontal by maxilla; interorbital region moder- 
ately narrow; supraorbital processes of frontals scarcely evident; 
frontals anteriorly depressed in midline; supraorbital region of 
frontals broad, so that the maxillaries are widely separated from the 
parietals; parietals extend anteriorly in supraorbital and orbital 
region but do not form an anterior process; supraorbital foramen 
present in dorso-orbital region of frontals; orbital region of maxilla 
broad, forming major portion of the anterior region of the orbit; 
orbital region of frontal constricted anteriorly by maxilla, posteriorly 
by parietal; orbitosphenoid anteroposteriorly expanded, optic 
foramen posteromedially positioned, anterodorsal to, and moder- 
ately well separated from, the suboptical foramen and from the 
ethmoid foramen (see Fig. 3); crest present leading from anterior 
alisphenoid diagonally across orbitosphenoid, partially obscuring 
optic, suboptic and sphenorbital foramina in lateral view; alisphe- 
noid dorsoventrally compressed, fusiform anteroventral process of 
alisphenoid present, well marked alisphenoid canal present; brain- 
case low and scarcely domed, lambdoid crest moderately 
well-developed laterally, low medially; mastoid large, slightly in- 
flated; paraoccipital process small; infraorbital foramen dorsal to 
P4; antorbital or prelacrimal flange present only as a low ridge; 
shallow antorbital fossa on anterior surface of zygoma; nasolabialis 
fossa shallow; maxillary component of zygoma narrow with long, 
slender posteroventral process ventral to well marked long jugal, 
slender anterodorsal process of squamosal portion of zygoma over- 
lying jugal; palate with paired maxillary foramina level with P2 and 
anterior of P3, small paired anterior palatal foramina, lying anterior 
to the suture between maxilla and palatine; palatal spine absent; 
basioccipital narrow with ridge in midline, tympanic wing of basioc- 
cipital slightly inflated. Mandible with deep, moderately broad 
coronoid process; mental foramen below p3. 
Dental formula: 3/3 1/1 4/4 3/3 = 22. Dentition robust (see Figs. 1— 
2). First upper incisor robust, distostyle present; I2 and [3 
sub-triangular, anteroflexed, distostyle present, 13 approximately 
half size of 12; C with anterior basal cusp and distostyle and two 
roots; Pl and P2 subequal in height, P2 longer than P1, both with 
anterior basal cusp and distostyle, P1 with two fused roots, P2 with 
two roots; P3 large, subequal in height to C, lingual cusp (protocone 
according to Gould, 1995) well developed, three roots present; P4, 
M1 and M2 quadrate in shape, parastyle well developed, meta- 
conule present on M1 and M2; M3 subtriangular in shape, with well 
developed parastyle and hypocone and metacone distinct in unworn 
dentition. First lower incisor larger than i2, both semi-procumbent, 
i2 larger than 13, which is anteroflexed with hypoconulid present; c 
anteroflexed, greater in height than i3 and p1; p1 and p2 subequal in 
height and both with a single root; p3 larger with two roots; p4 with 
well developed paraconid and talonid; m1—m3 with well developed 
paraconids, m3 less than half size of m1. 
ETYMOLOGY 
The name of the new species is derived from the Greek p¢éyac 
(megas), large; ®t6c (otos), ear; the ears are large in comparison 
with those of other species of Hylomys. 
