Lasionycteris noctivagans

Abstract

CONTEXT AND CONTENT.Contex t noted in generic summary ab ove.No subs pec ies are recognized .DIAGNOSIS.Th e color is the most distingui shing external feature of Lasionyeteris noetivagans.Indi vidual hairs are dark brown to bla ck , with silvery-white tip s imp arting a fros ted or silvery appe arance.Th e interfem oral membran e is furred above on th e basal half.Thi s species is distinc tive and is not likely to be confuse d with others (Fig. 1).GENERAL CHARACTERS.Extern al charac teristics of a dult L .noctiuagans in clude bl a ck wings, ea rs and in te rfe moral membrane.Ear s are short, rounded , and nak ed , with a broa d , blunt tragus.Th e white -tippe d dorsal hair s ar e more conspicuous in young than in adults (Merriam, 1884;Miller , 1897 Miller , , 1907;; Naso n, 1948).Old er adults may lack th e white-tipped hair s (Se ton, 1907) or may app ear yellowish (Barbour and Davis, 1969).Measurem ent s of adults (in mm) are : total length, 92 to 115; length of tail , 35 to 45; length of tragu s, 5 to 9 (Jackso n, 1961; P ear son, 1962).Adult mas s ranges from 8.1 to 11 g; femal es hav e mor e subc utaneous fat than mal es in winter (Layne, 1958).Selected cranial mea surem ents ar e given in Grinnell (1918), Miller (1897), and Williams and Findley (1979).Th e skull is flatten ed with a broad rostrum.Th e depth of the braincase, including th e auditory bullae, is ab out three-fourths the ma stoid br eadth.Th e int er orbital region is wide and f1 att ish .Th e upper surface of the rostrum ha s a distinct conc avity on eac h side betw een th e lachrymal region and th e nar es.Oth er fea tures of th e skull ar e esse ntially as in M yotis exce pt for a genera l tend en cy toward br oadening and flattening.Th e dental formula is i 2/2, c 1/1, pm 2/3, m 3/3, total 36.Illu str ati ons of the skull and dentition are given in Grinnell (1918) and Miller ( 1897), including a ph otograph of th e s kull.Ph otographs of L. noctivagans ar e shown in Barbour and Davis (1969) and Se alander (1979).Th e s kull is illustrated in Fig. 2. FOSSIL RECORD.Fossils of Lasionycteris are known from th e early Blan can at the Beck Ranch localit y in T exas (Dalquest.1978) and the late Pl eist ocene sites of Littl e Box Eld er Cave and Bell Ca ve of Wyomin g (Ande rso n, 1968; Kurt en and And er son, 1980).