Studies on the Two New Zealand Bats
III. Hair Structure of New Zealand Bats
III. Hair Structure of New Zealand Bats
Hair structure of Chalinolobus tuberculatus (Forster) is distinct from that of C. gouldii Gray; in some respects it agrees with the generalized vespertilionid structure but differs in the lack of separate overhair and underhair. In Mystacina tuberculata Gray, both hair types are present; overall structure is clearly different from that of the Molossidae but corresponds closely to that of the Noctilionidae and Nycteridae.
The present paper describes the hair structure of the two New Zealand bats Chalinolobus tuberculatus (Forster), F. Vespertilionidae, and Mystacina tuberculata Gray, F. Mystacinidae, and examines the affinities of these species in the light of this. Hairs from the mid-dorsal region at scapula level were examined and sketched using a camera lucida. The terminology of Benedict (1957) is followed.
Chalinolobus tuberculatus (Forster) (Fig. A.)
In C. tuberculatus there is no differentiation of hair as overhair and underhair. The long, fine filaments are of fairly uniform diameter and lack a medulla. Filament length is from 4 to 7 mm with the maximum diameter, 15μ, occurring both above and below the midpoint (diameter 12μ). Distal scales are about 15μ in diameter and the hair ends as an acute projection formed from two or three incompletely developed scales.
Melanin is concentrated in the proximal half of the filament; the maximum density occurring about a third of the distance along the hair. Within each scale the melanin is arranged dis.tally except in the distal portion of the hair where the few granules are scattered irregularly. Scale arrangement is annular. Scale form in the proximal half of the hair is medium, divergent or divaricate, equal or unequal hastate coronal but distally it becomes short, slightly divergent, equal hastate coronal. The terminal scales are slightly longer than those preceding them.
The hair structure of C. tuberculatus agrees in some respects, such as the hastate coronal scale form, with the generalized vespertilionid structure described by Benedict (1957) but it differs in the lack of distinct overhair and underhair. Benedict described C. gouldii as being the only bat in which the hair scales show entire margins in the proximal third and denticulate margins thereafter. In this respect and in the coarser nature of the filaments C. gouldii is strikingly different from C. tuberculatus. In the lack of differentiation of overhair and underhair and in the arrangement of the melanin within the filament the two species agree. The two species of the African Glauconycteris described by Benedict are clearly separated from Chalinolobus in details of hair structure. In both G. humeralis and G. varigata papilio overhair and underhair are present and the melanin is dispersed generally, not in bands proximally as in Chalinolobus. The scale form of the underhair is short, appressed, hastate coronal except in the distal third of the filament of G. varigata papilio where it becomes lobate.
The two trends away from the typical vespertilionid scale form which occur in these closely related genera are represented more completely in other genera. Thus Scotophilus has lobate coronal scales and like Glauconycteris has both overhair . and underhair and Mimetellus has dentate coronal scales and corresponds with Chalinolobus in the absence of distinct hair types.
Mystacina tuberculata Gray (Figs. B, C.)
Overhair and underhair are represented in the fur of Mystacina. The coarse dark overhairs are scattered amongst the close layer of short and wavy underhairs. They are long and straight and of irregular diameter, having a long, club-like thickening in their distal two-thirds and one or two shorter thickened portions near the base. No medulla occurs in either hair type.
Filament length of overhairs is 7-8 mm. Maximum diameter of the distal club is 30μ, that of the shorter proximal swellings 27μ. Terminal scales have a diameter of 6μ, the base of 11μ and the constrictions between the swellings 13.5μ. The tip is bluntly rounded. Melanin granules are scattered in irregular longitudinal bands through the length of the filament with the greatest concentration about midway along the distal club. This club has a narrow outer zone free of granules. Scale arrangement is annular. Scale length varies considerably along the filament from 7.5μ at the base to 17.5μ in the proximal swellings and thereafter decreases to about 6μ, toward the tip. Scale form is appressed to divergent, entire to repand coronal at the base and at the constrictions between the swellings, but is appressed, entire to repand coronal in the swellings and terminally.
In all the overhairs examined a long distal club-like portion was present, but some variation in the presence or absence and in the number of proximal swellings occurred. Usually one or two of these latter were present. In some individuals a number of the overhairs possessed a swollen bulb-like portion at some interval along the length of the distal club.
Filament length of underhairs is fairly uniform, about 6 mm. Diameter is greatest, about 12μ, at the middle. The filament tapers proximally to a diameter of about 7μ and distally to about 5μ. The tip of the hair is oblique. Melanin granules are scattered in irregular longitudinal bands through the length of the hair with the greatest concentration present at the middle of the filament. Scale arrangement is annular. Scale form is long (about 18μ), divergent, entire (oblique or rounded) coronal for the greatest part of the filament but becomes shorter (about 7μ), appressed distally.
The peculiar nature of the fur of Mystacina has caused comment by several previous authors. Gray (in Dieffenbach, 1843a) and Tomes (1857) describe the close body hairs and Tomes compares the "grizzly shiny appearance" of the fur with that of some Soricidae. Dobson (1878) indicates the appressed nature of the shaft of "each of the long hairs" and states that the quality of the fur is alone characteristic of the species.
My findings differ from the description given by Benedict (1957) in that I have distinguished distinct overhair and under-hair. Benedict's description appears to apply only to the overhairs yet these are scattered. The scale form in this work is described as entire to repand coronal in contrast to Benedict's "very uniform coronal".
Fig. A---Chalinolobus tuberculatus (Forster). Fig. B---Mystacina tuberculata Gray, underhair. Fig. C---M. tuberculata, overhair.
The origin of the arrow indicates the section of hair which has been magnified. For each figure the smaller upper scale is that of the complete hair, the lower scale is that of the individual enlarged lengths.